Centrifugal Blower vs Turbo (Twin Turbo vs Single)
 

Hey Guys

Just mapping out a build plan and had a couple questions regarding the pros and cons of a blower vs a turbo and what you would prefer. I have a c5 z06 with cam and headers and my driving would consist of mostly spirited drives with the occasional trip to the strip and a rare trip to a road course. Just curious what you think the best build plan would be and why.

Power goals are roughly 600-700 and even then im sure will be too much power for a road course but I do prefer strip more then anything and what Im aiming for above all in the build is reliability and versatility.

Transmission needs to be a 6 speed manual and my budget is roughly 15k canadian which should afford me a nice turbo or blower set up with some mild motor work and that sounds good to me. No particular goals to run a certain et at the strip or time on the course, just want a fast reliable power adder to a car that im in love with but want more out of...... and I want to be faster then my friends.

Regarding the blower, I am a big fan of the linear power and the ease of build but was most concerned about belt slipping and the cost of mods after the initial build is complete and the all around longevity of a centrifugal blower set up.

My concerns with a turbo would be to have it set up properly so the turbo is not kicking in mid turn on the road course and having something that is also applicable at the strip. I was curious as to why most guys opt for a twin turbo set up as opposed to a single turbo and what advantages and disadvantages there may be and if it is more reliable then a blower

I originally began with the idea of having a blower but Im falling more and more in love with the versatility of a turbo.

Please let me know what you prefer and maybe what you did or didnt do with your set up that you may regret

for road racing you are going to need great cooling for blowers or turbos. the turbos are nice in that you can turn the boost down as typically road racing you will already have trouble planting big hp and brakes and handling can become more important.

I don't like running a blower as you are going up and down the rpms quite a bit in road racing and it can be hard on the blower and belt. With turbos they are load dependent and running boost by speed or gear can help on a road course.

I like a bit shorter stroke on the track to allow a wider power band and not put so much side loading on the piston. The little 4.8 crank works pretty well and is strong.

Use turbos that spool well off the corners and you will make a bit more mid range torq than the blower which is rpm dependent for boost

This thread has all of the answers. Read till the end to find out which one wins at the track.

https://www.corvetteforum.com/forums...-tt-vs-sc.html

Twins can make the plumbing easier for V style engines, allow the tyrbos to be closer to the engine for less lag, and in theory having less mass will build boost faster.
Plus they are just cooler. :cool:

You dont mention power goals, or any real goals, or indeed budget, or transmission.

Clearly say 6-700hp will have different implications than 1000hp

But very loosely....sub 800hp go Centri.
700-1000 could be either depending on budget.

Over 1000 for most part turbos will make most sense.

That isnt to say turbos could not be used at the lower end ( and anywhere else )...but there are just a huge range of variables and how power is delivered is very much dependant on those as well as your right foot.

Over 1000 on a centri can of course be done and has been many times, but yes belt drives are getting pushed very hard at that point.

Power goals are roughly 600-700 and even then im sure will be too much power for a road course but I do prefer strip more then anything and what Im aiming for above all in the build is reliability and versatility.

Transmission needs to be a 6 speed manual and my budget is roughly 15k canadian which should afford me a nice turbo or blower set up with some mild motor work and that sounds good to me. No particular goals to run a certain et at the strip or time on the course, just want a fast reliable power adder to a car that im in love with but want more out of...... and I want to be faster then my friends.

I just feel with a turbo there are more options, its powered by exaust gases instead of drawing power from the motor (in my perspective safer) and its easier to make more power should I ever get the itch or get bored.

What in particular would make you want to go blower sub 800?

What size turbo would you recommend with an LS6 for all around versatility?

what made you want to go to turbos over supercharger? anything you would have changed on your set up if you could go back?

For the amount of money saved with a single over twin turbo setup, would you say its more worth it to pony up for a tt setup or would a single do just fine?

Quite simply cost...ease of access, throttle response, feel...general performance.

TT kits will cost a lot more, but yes you could use a pair of very small turbos aimed at that power level which should also give very good response down low.


But all TT kits will be far far more expensive than a blower kit and for that level....is the extra cost really justified ?
Obviously that depends on your budget.

Although one easy benefit of turbos....is you will have far easier access to a wide range of boost and hence power/torque levels at the flick of a switch on a boost controller which might be of benefit for varying courses or weather.

But there are probably more proven blower kits out there, than turbo kits although I think turbo kit options have become slightly better in recent years
Most are twins, dont think I've seen too many single kits ?

The only single kit that I know of if the Hinson and that kit is so far from being a complete "kit" that I can't recommend it to anyone who can't do their own fabrication.

I generally prefer turbos in most applications, having had both supercharged and turbo vehicles of different types.
I got the long deal on an STS twin rearmount system w upgraded BW turbos.
TBH, for my purposes I would have stayed with the smaller ones. Im at 534hp 10# and a dead stock engine/ mild tune, so not using the potential [yet]
I do like the fact the turbos are out of the engine compartment, which would be an advantage on road racing. The kits came with various brands and sizes originaly.Smaller ones may be better for a road course as well.
The plumbing is pretty complex, though. Installation a bear. Lag is worse.
I have a few frends runing LS singles in the 76mm range that seem to work well
If you have fabrication skills and time, you can build your own setup. If you have money? I would have gone TTix if I could afford it.
For cost and ease of installation though, its hard to beat the blowers

A rear mount turbo setup would most definitely be the last option.....Even a 454 n/a might get you close to your goals before I'd choose rear mounts.

I do not see how any custom made turbo kit will be as cheap as a simple tried and tested bolt on blower kit.
It just aint happening unless you were doing all the fab work yourself.

And for the reasons others have mentioned, a single is probably going to be the hardest of all options for zero benefit.

Names that get mentioned for TT kits, and I believe there are a few threads are UPP and Huron Speed, not sure if TTix is still about ?

A quick google... and in no particular order.

https://uppturbo.com/parts/turbo-kit/

https://huronspeed.com/product/huron...fer-deposit-2/

Canadian ?

https://canadiancorvetteforums.com/t...urbo-kit.7130/

Huron Speed in the link above has been doing a lot of turbo kits for a variety of LS platforms recently with all good reviews, that would be something to look into and they seem to be very well priced.


As for performance, lag, whatever.....twins vs singles. Sized appropriately for the application there would be very little difference.. But when there are almost no single kits available and there are twin kits available.....it sort of makes that decision easy.

My mechanic did recommend a rear mount set up and it seems like that would take care of part of the heat issue under the hood, but you all would know better. How is the lag in the single compared to twins and is it bearable to you? Are your friends single set ups still half decent at the road course or is it just more roll racing and digs? How much did your friends save by going single instead of twins?

Thanks a lot for the info and answering the question of single vs twin and If boost lag is an issue. When I priced out a blower and install last fall it was roughly 12-15 Canadian. 6k us plus shipping and then taxes and conversion take a big toll on pricing for us Canadians and still need labour on the install plus tune. It most often times works out to double the price. I just figured if I’m in for 12k why not spend 15k to have more options for tuning and drivability. Not too knowledgeable about what needs to be done for a turbo kit so the quote from my mechanic sounded decent to me in comparison.

I’ve never heard of phobia innovations, I’m from toronto Ontario so theyre roughly a 22-25 hour drive for me

Really appreciate the insight, I’ll check upp out

I would say there would be less work fitting a blower kit than there would a twin turbo kit if labour is expensive.

But each does have their pros and cons.

The base Huron kit is well priced and maybe you could source turbos locally in Canada to help reduce costs ? or maybe it'd make no difference overall.

Would it be anymore cost effective to drive to a shop in the US if there were any semi-local, have it fitted then drive home again ? Make a holiday/vacation of it.

Yea I don’t doubt that at all that labour is a bitch, my mechanic is a good friend that does strictly custom turbo kits at his shop and he said he was willing to help me out and give me his pricing on everything so it will be close to a blower pricing.

When I was still thinking blower I was going to drive to Ecs (8 hour drive) which would have saved me a bit of money on shipping and taxes (1500-2000) but even then still would cost me over 10k Canadian when said and done.

Would definitely not be opposed to a road trip at all. So if any accredited shops have a sale or promotion I’d be very interested.

Took a while to read but was very informative and pretty entertaining hahaha. I like a lot of what you said about a turbo set up, anything you would change if you could go back and do it again?

Also did you ever race that guy? Lol

Looking at their website etc ( well FB ) Huron Speed are in Port Huron MI.....that's pretty close to Toronto ?

https://www.facebook.com/HuronSpeed

Not sure whether they do installs there, but they're bound to have someone local who can given they've developed quite a few turbo kits for LS equipped cars.

Yea they're right at the border too, maybe a 3 hour drive from my place so no need to pay for shipping, if only there was a way to get around customs. Whats the approx install time of a tt setup, could it be done in a weekend?

If you drive away...and drive home....what changed ?

And with a TT setup it certainly wont make any louder noises.

You'd need to speak to the seller/supplier about install/tune times etc but I'm sure if it was all pre-arranged it could be done in a few days no problem.

Yea I had that in mind but was concerned about risking it and getting stopped there. Thanks for all the info

I'm sure the concerns are genuine....but would they really go so far as to check the car is exactly the same spec as it was driven on the outbound journey ?

I'd say good luck would be on your side for that, although of course yes it would carry some risks.
But an option nonetheless.

Just dont do anything silly like have invoices sitting on display in the window lol

OMG​​​​OMG LOL WTF. That thread!

I came for the knowledge... I stayed for the drama.

If money does not matter, as in, you could drop $40K today on a motor and not care at all, then do a turbo set up.

If money does matter and you are certain that you won't ever want more than 1000 at the wheels, do a YSi Vortech kit and be done with it.

I've done turbos, centrifugal superchargers, and nitrous (currently have a nitrous car) and I can guarantee that no matter which way you go, all of it is a lot of fun.

Yea im sure id be able to get away with it, just seemed like a decent sized gamble. Ideally Id like to get it done in town but if it makes more sense to head south then ill be doing that for sure.

hahaha yea. At one point I wasnt sure if I was going to see a race or a fight posted. some good info though!

My budget is roughly 15-20k to have a stress free reliable build at low boost. Why would you suggest a ysi for anything under 40k? From what ive read it seems like a couple guys have some reliable turbo builds at low boost for around that cost and they have the option to turn it up and program different tunes for different driving styles instead of having to puley up or down.

I personally would prefer a turbo (just my uneducated preference) and money isnt the biggest issue but i dont want to get caught in a trap of pouring money into a car that is consistently down. I guess my question is can I make a reliable single turbo set up that has minimal boost lag and is safe for under 15k?

I'd go huron turbo and never look back. sure the blowers will make all the jam you need but they load the crank, are harder to do fancy stuff like boost by speed, and the turbo you can get more mid range torq and it's MUCH easier on the motor

sheesh, bring me 15k and I'll slap a little iron block in that bad little b

lets talk some realistic numbers

iron block forged short block 3500
huron twin turbo (on sale) 6000
injectors 127 fic 800
pumps walbro 450 intank, bosch external 1200 for pumps and lines fittings ec

heads (I use cheap 6 bolt cathedral port castings)

600 for the pair

get some truck iconel exh valves, turn down some ls9 intakes (200 for valves, price of a good valve job)

ls6 intake
direct port meth (pumb each intake with a spider direct port to get good fuel distribution)

now you've burned through most of the 15k, but you have something that will go for MANY miles and give you tons of flexibility

if you can afford it, go with E85 from the start and step up the pumps and injectors to 160 and the injectors get cheaper still

I don't disagree that the blower will make the same jam, but after lots of miles on turbo builds I'm happer with them and you don't have to refill the bottle or have quite as strong a bottom end to live with the hp

here is my current "low buck" build

stock 4.8, bored .020 over, wiseco turbo pistons, stronger pins
gen 4 rods with upgraded bolts
stock crank

with the short stroke the stock crank gets stronger and the little thumper can pull up a bit higher to stay in the sweet spot of the turbos longer

I'm a bit limited on turbo size with the ttix kit, but with the huron you can go much bigger on turbos and push over 1500

what you are going to do for a drivetrain then becomes the problem so then your 15k is again out the window.

to do this with a blower the ysi kit is a bit cheaper, but you should get the good stuff on the drive system and I think the 6k is about a wash now that more affordable kits are out there.

Are those "consistently down" cars you're thinking of down due to issues with the power adders, or down due to issues with the power? I mean, the pistons / rods / crank / clutch / trans / diff / axles / etc probably don't care too much about whether they're downstream with a turbocharger or a supercharger, they just blow up when whatever it is finds their limits. $15k for power adders seems like more than enough to find a few of the weakest links in that chain. :)

Thanks for the breakdown, thats the exact kind of post I was looking for. Ive seen a couple posts on here about turbo 5.3s in a c5 and some of them have run into issues with running too much power in the car and others being quite reliable.

How much did the main ingredients cost on your "low buck" build? Im sure youre constantly doing small little additions but for something that is 700ish and reliable with tunes for the track or street driving, how much would that run me?

In most cases its due to running too much power. I was just essentially looking for "the sweet spot" of making a nice amount of power without replacing too many parts. From what Ive read, a turbo on low boost (12-15lbs) with a good setup and meth should be more then reliable for everyday driving and the occasional trip to the track. Do you have any info that says differently? I would prefer to be almost all in for that 15k and have addressed any issues that would effect longevity or reliabliity.

you can get 4.8/5.3 engines for cheap. I drove to NC and picked up an alum 5.3 gen 4 motor for 400 it has the 799 heads which are nice

I use wiseco pistons which are about 700 for the set

balance, hone, short block assembled was 2k counting pistons

on one iron block motor I got an even better deal. bought 1 wiseco, rehoned, fresh rings bearings 1250

there are deals out there with forged pistons these engines will take 800 at the tire whithout much drama on e85

I run about 18.5 psi to make 800 at the tire

I'm not disagreeing - I just got a Corvette a few weeks ago, and I've basically got the same questions you do.

It would be interesting to know at what power level (torque, really) the stock trans, diff, torque tube, and axles become problematic. It seems pretty straightforward to find the cost for making X horsepower, but I'm not at all clear on the cost of drivetrain upgrades to handle X.

What upgrades does the drivetrain need to stay reliable at that point?

Transmission? Torque tube? Driveshaft? Diff? Axles? CV joints? Anything else?

Because turbo build budgets can get waaaay out of hand quickly. You were half way through and then decide you want to change this or add that, or do this differently, or fab that this other way, or something didn't quite go as planned.......and before you know it, you're balls deep but not finished and over budget.

You don't have to spend $40k on a turbo build, but it's an automatic green light for a super nice turbo set up if you couldn't care less about dropping $40K on a build. Make sense?

On the other hand, a low hp (600'ish at the wheels) YSi build is fairly straight forward and can materialize in a 3 day weekend because it's close to being a "buy it and bolt it on" scenario.

1) Order a YSi kit and bolt it on
2) Swap out your fuel pump for a Walbro 450
3) Swap injectors to Bosch 127lb'ers
4) Fill you tank with E85
5) Flatbed your car to your tuner
YOU'RE DONE. GO HAVE FUN.

I would expect the Huron TT kit to be a weekend job too for a competent person ?

But a full package of fuel system mods will require more time...as will any supporting mods like clutch etc.

But it's hard to go wrong with a YSi both at lower power levels and high, it is a great head unit that will cover a lot of options

Couldn't agree more! I know stock clutch is typically rated at around 600 before issues start coming and the rear end may be a little less if you beat on it but I have read of a lot of guys running blowers with around 600 whp and stock clutch and rear end for a while.

With reliability and longevity being my main concerns on this build, Im very curious of what should go along with a 700whp turbo car in terms of what you just mentioned so I can spend as little time on the side of the road as possible

I definitely agree with what your saying and thats why I wanted to ask these questions before hand. That being said, Im having a professional that has been strictly makes custom turbo kits for over 5 years do this for me and I would think that there shouldnt be too many mistakes or mind changes during his process.

Another issue with getting a YSI is the conversion rates I mentioned above for bringing it to Canada. After taxes and customs I typically end up paying 1.5-2 times more then what the kit actually costs so making a custom turbo kit and only buying some parts may end up being the same price being that most of the cost would be for labour.

How much would that YSI set up you mentioned cost after install and also would I need to do any necessary clutch/transmission/rear end/etc. upgrades after that install?

Doesnt matter where the power upgrades come from....if the power is there then it can place stock drivetrain components at risk.

A healthy helping of common sense when it comes to how hard you can push it and keep it together.

When I built my previous Z06, I started with the drivetrain mods - DTE trans brace, upgraded stub axles, etc.

My biggest concern was the structural stability of the trans/diff connection, which has posed a breakage problem for many people if the car is driven hard. I figured I'd strengthen that area first.

My stock clutch gave up during a 4th gear pull on the highway, power just pushed thru it, still drivable but I knew it would not hold the power any longer.

I had about $16K in mods in my 2002 Z06 with a twin turbo kit, the drivetrain mods mentioned above, an RPS triple carbon clutch and full 3" exhaust, and I did all the work myself.
It adds up quick.

Yea I definitely agree with that. In order to run ~700whp, which components, in your experience, would without question need to be replaced?

Just curious how much boost you were running to make that power and also what are your driving habits? do you tend to have a heavy foot and beat on it or are you more about preservation?

Only asking because I'm confused now....why is the Huron kit even a consideration if you have a good friend who has done custom turbo kits for the last five years?

The YSi kit from A&A is about $6,700 with the 6 rib belt set up. http://65.110.95.157/shop/product/c5-supercharger/
No idea on install cost as that is at the discretion of your mechanic/installer.

Again, after realizing you know someone (who I believe you referred to elsewhere in the thread as a good friend) who does custom turbo kits, why is anything else even a consideration?

My philosophy on drivetrain durability improvements on a daily driver is to NOT do any. Only upgrade the clutch since a stock clutch just wont hold. I buy diffs, trannys, torque tubes, and engine parts as I come across them cheap, rebuild some stuff if it's cost effective, and keep them in the garage. Parts brake, I swap them out. Since I do literally everything myself other than machine work and tire mounting, it is much less expensive to simply swap broken parts.

Okay, but which of those parts are likely to fail in the OP's scenario? 600-700whp, some drag racing.

The OP has a budget and is trying to plan ahead. (And I'm wondering the same thing, for the same reasons.)

I was running about 10 psi or so.
I pounded on that car all the time, 50-140 runs were the norm.
I also drove it like a reasonable human being but I had no qualms about flatfooting the gas pedal on a regular basis.

This still isn't making sense to me. Why would you have to ship a kit to a guy that buildscustom turbo kits? You have to make the distinction for us....does this guy "install turbo kits", as in, obtains a pre built kit like the Huron and simply installs it? Or does he legitimately "build custom turbo kits", as in, he is an experienced welder and fabricator, has all raw materials and tools on site at his facility, you tell him what turbo(s), waste gate(s), blow off valve(s), and intercooler(s) you want, you two discuss the location and orientation of said parts, and he then mocks up and custom builds all exhaust and intake plumbing with corresponding flanges and mounts for all parts you have specified?

I promise I'm not trying to be difficult. I'm seriously just trying to understand what this guy actually does to help determine the best/least expensive route for you.

Unfortunately, breaking $hit is part of going fast. There's no way around it. If this car is intended as a fun, good weather driver with some occasional road course/drag strip shenanigans, leave everything stock and swap parts as they break. If you want a legit drag strip beast that occasionally sees the street, put a powerglide and a solid 9" rear end in that thing.

Perfect. It sounds like you have the opportunity to witness parts of the C6 build as it happens. Ask if you can come along for a ride in the car when finished. If it's everything you imagined and more, let this guy build you a turbo kit.

No problem. Good luck with your build. :cheers:

The last option I'd recommend would be a rear mount kit.

Because it is by far the least efficient

Turbos need heat in the turbine, they like exhaust gas velocity. Both of these things mean the closer they are to the exhaust valves the better.

In theory, the more volume there is between the heads exhaust values and the turbine, the more time it will take to pressurize that volume, and thus the slower your boost response will be. Ditto for volume between the compressor outlet and the intake valves. You'll also lose some heat (which also leads to less pressure).

In practice, I have no idea how pronounced the effect is. It would be interesting to see data logs showing the elapsed time between stomping on the gas pedal and getting Xpsi, from two cars with the same turbos, one rear mounted and one front mounted. But I'm not holding my breath for that data...

Since we're talking about custom kits, here's something I saw posted to Facebook a while back... I'm amazed it all fits. Looks great though, and it seems like just about the smallest possible intake and exhaust volumes.

Wouldnt that be a total fucking nightmare to work on, change plugs etc !!

The APS/Huron low mount twins have a lot going for them.

Or just opt for the supercharger.

Dont add complication or inefficiency where it doesnt need to be there

Yea i was definitely expecting some boost lag with a rear mount set up. Though I have also read that putting the turbo under the hood causes a significant amount of heat under there that some of the plastic components dont like. Ive also read in a couple posts that there is actually minimal lag if you set it up properly but that could be subjective. If you could build a custom system, how would you set it up?

I agree withs stevie turbo, Its good to know it all fits but that looks like an absolute bitch to work on. Another aspect I enjoy of a rearmount is the ability to appear mostly stock. What set up would you opt to go with if you had a choice?

As already said and I'm not advocating it because I've anything to do with them etc....I just like the look of it.

But the Huron TT kit looks an ideal budget setup ( or a Vortech etc )

My own car is an LS swap vehicle, for the first 10 years or so I ran it with a YSi and it was superb. But temperamental with belt issues from time to time, noise and the desire for more power pushed me to swap to twin turbos. That said being largely DIY the belt issues were sort of my own and a lack of experience. I did get it nailed very well at the end but I'd already decided to switch to turbos anyway. Although if there had been a drop in unit that replaced the YSi but was larger, I would have opted for that. But there wasnt.

Both have pros and cons, in many respects the Vortech was a bit more exciting, but ultimately my turbo build has been more reliable and much quieter. Not that it gets driven daily anyway for that to be a huge concern. But I just like things to be more subtle.

After seeing what AGP offered for the Gen5 Camaros with a low mount twin ( and I guess a little the original Vette APS kit which Huron have followed ), I decided to build similar for myself using factory cast truck manifolds as a base.
No matter where you mount there are pros/cons too...but for me the only real negative is mine are very low and I have limited space for filters..but I do have filters there.
The Huron kit would not suffer this though, nor does the AGP for the Gen5, at least not as bad as mine
Whilst it is no longer available, here is the APS kit they still list on their site with some good photos to give you an idea of how it is installed.

http://www.airpowersystems.com/corvette/c5.htm

But up top things look relatively standard, spark plug access is as easy as an OEM vehicle would be, the turbos really arent visible at all, downpipe from the turbo is almost a straight shot rearwards and in all...it just worked out great for me.

Spool from mine certainly isnt instant or anywhere near it, but as I opted for slightly larger units with a potential 1500hp or so headline...I never expected it to be.

Of course you will always see people claim instant spool, spool like a light switch etc etc....and every time I call bullshit on that. IMO no turbo setup will ever feel like a blower, even a centri which although you may not see gauge pressure at lower revs, they are still moving a lot of air to assist power vs n/a, and I've run mine back to back without the blower to know this.
All those who claim instant spool..I always ask to show a datalog with throttle/rpm/map to prove this "instant"...and none have ever produced the data.

It isnt to say spool cannot be very fast...but that isnt instant as it would be with a blower. And the silent rush of torque from turbos will always be fun and addictive.

So both are excellent options. But a rear mount ? It is just at the bottom of all "wish" lists, other than perhaps cost and partial ease of install, or if there are some sort of legal requirements where you cannot tamper with existing emissions equipment up front.

For lots of TT info, check out the Gen5 and most commonly AGP kits. Lots of users there. Even with fairly small turbos guys there are easily making in the 4 figure range.

http://www.camaro5.com/forums/forumdisplay.php?f=74

http://www.camaro5.com/forums/showthread.php?t=208952

But turbos can give you much more flexibility with power and power delivery because it's easy to play with boost control whether by rpm, speed, gear, whatever. ( with a suitable controller of course )
Not so easy to achieve with a blower.

So I'd probably opt for the twin kit, a pair of decent brand name small turbos, a pair of BW S200's or something like that. Whilst Chinese turbos are cheap and popular these days....when a proper turbo is only a little more I just cant see the sense in skimping on such an important piece of the puzzle. Even more so if it's a fun daily driver.

Or the blower. It is a tough choice between them really. Some might like the audible noise of the blower, some might prefer the silence of the turbos. But both will be awesome.

As others have said whilst a single may be possible....there do not seem to be any kits offered like that, so that must give a clue that they are more difficult to achieve so probably best not to go down that route.

Thanks for clarifying that for me, i assumed it was subjective in their cases.

Everything you say about your car being reliable and looking stock is very appealing to me.

Thanks for all the info, really appreciate it.

Rear mount is the most expensive to do right, but it is in some ways, the best option for limited space vehicles. Turbo tech has come a Looooong way such that the right turbo and large engine combination negates some 'lag'. Ex, There are 2k whp vettes on this forum using twin rear mount, oil-less cartridges (no oil feed / drain lines) and approx 427cid of displacement. If you only wanted say 800 this would dramatically lower the rotating weight of such a cartridge and it would not 'lag' as much.

The approach is elegance, fabrication, time consuming artwork with a full shop + tig welder. Which is another 'best to have'- when the fab work is worth more than the car, or on level with, in essence, it becomes the car.

When power due to boost gets up beyond a certain point (say 23psi), the term "lag" becomes obscured as the engine's own cam/head/intake moves the powerband up past 5k region anyways which is where you were "lagging" in the past with more-stockish engines. So it is normal to see 23+psi of boost after 5k+ once the engine's own combination and overlap profile etc.. is 'coming in'. I wouldn't size a turbo so large that it delays boost to 5k on a stock-ish engine, that is simply a mismatching in progress. run matchbot on borg warner site to determine turbo size. Normally placement near the engine is desirable in turbo applications, at least this is the first thing most will say or think. However, in high power applications the exhaust gas temperature immediately leaving the engine is too high for turbine entry, "The turbine housing, based purely on the specification, should not see more than 1382° F. " -Borg Warner, so some distance may be desirable, depending how the EGT is controlled in the application or how reliable it is intended to be. Longer distance, high sustained speed, higher EGT situations would benefit from more rearward turbine placement where EGT is still very high but not too high as near the engine.

The degree of onset, slowing rate of change of torque to the tire is an advantage when tire is limited, so called "boost ramp in rate" is a key in traction with poor grip, something a supercharger might struggle with, where the larger breathing turbines may excel naturally with. Being able to dial in and customize a boost rate of change is one of the main benefits/reasons to use turbocharging in racing.

Any unlimited class application in racing where any delay due to "lag" needed to be fixed, it could be done using nitrous. There is far more to gain by keeping the large high flow turbine and spraying a small progressive shot to get it going.

Finally, if you did size the turbine for a street engine (3000-6000rpm powerband) you would also bring the converter down (2800~) the cam down (~228* @ 0.050) And use an appropriate intake/head with small enough ports to have high velocity in the mid-range to maintain proper throttle response, with small enough throttle body to have good resolution of airflow at low positions, etc... As these will play a large role in part throttle transitions just like they did without the turbo, to help the vehicle feel snappy and responsive. As always there are a bunch of little tricks that will help depending on the goal of the vehicle.

edit: was just reading around and saw a random rear mount
https://www.corvetteforum.com/forums...post1595978876

With v-band clamps on the downpipes (one near the turbo, one down by the frame rails) you could get them out of the way and it might not be so bad to work on. Maybe. I think you'd want a very ventilated hood though, and the clutch reservoir looks like it's in a good spot to get cooked.

I'm leaning toward A&A's Ti blower with an 8-rib & secondary drive, probably way overbuilt but I like the idea of overbuilding the install to minimize surprises later on. And since I'm coming from a turbo Subaru, I'm leaning toward a supercharger just to see if the grass is really greener on that side of the fence.

Also, compression in the 8.5 or 9.0:1 range, and straight pump gas (no water/meth injection). Less power, but fewer things to go wrong. Corvette folks seem to like water/meth a lot, and it's not unusual in the Subaru world, but I figure that if a Subaru EJ can make near 400whp without it, then a Chevy LS with more than twice the displacement should have no trouble at all making less than twice the power (700ish would be great).

This is all pipe-dream stuff for now though. I just splurged on cooling, handling, tires, and brakes, and I don't plan to buy anything else for the car for another year. I'm sure it will be plenty of fun this summer. Plus I want to learn more about what's going to break with more power, so I can upgrade that stuff first.


Edited to add: Rear-mount might look stock, but it won't sound remotely stock because they don't leave much room for mufflers. :)

For the LS, it would be rare to ever need anything lower than 9.0:1, unless you wanted to run a decent amount of boost on say straight 91.

IMO 9.0:1 dead is a good all round figure with plenty of margin for a pump fuel build.
Many will say higher, and for E85 etc it seems you can go very high.

But for say 93 it's a good number and you'd easily be able to run 20+psi with that, or more with meth too

And anyone who says a rear mount is the most expensive or best...please just completely ignore them.

In my swap I used V-bands and removed spot welds from core support to make the front end come off with just 4 stainless bolts. So the engine doesn't need to come way off the ground, and I can push the car into it by myself, and it is fast.

Thing I learned about V-bands is if you plan to rip the engine out in a couple years real quick, a 1-day engine swap, you need to be maintaining, oiling, use anti-seize, and protecting those v-bands from corrosion over that time. Keep checking them and oiling them every couple months. And do not overtighten them, it does not take much. I actually think mine are loose enough to leak when the engine is cold, and as it warms up they stop leaking. I let an exhaust shop weld just 1 v-band clamp on the rear when I was letting them add the tail end of the system, and they had never seen a v-band before. By the time I remembered to tell the guy "By the way, don't overtighten it" I had run backoutside to tell him and he had already bolted it in. I was like "nevermind" when I found out he already put it on, and wondered how bad it was. Well let me tell you the next time I tried to take it off, I beat it, I used a long prybar, I really beat the E@()*#@ out of that clamp, and it would not come off. I've had to take the exhaust off twice now for transmission removal in the last 3 months and had to just remove the entire section instead of the two separate pieces because of me not reminding somebody not to overtighten it.

Thanks for all the advice. Due to my power goal and my typical habits with the car, I was planning to go with a smaller turbo to get a quicker spool and worst comes to worst I can swap the head unit. I had always assumed that a good tune can fix most things and there will always be an example of it but at the end of the day there are things that are just done easier and more commonly. In your experience, what would be the best turbo set up for a c5 corvette?

Although I wouldnt mind a small shot of nitrous, Im aiming for reliability on a somewhat decent budget so Im trying to keep mostly stock internals for as long as possible however I wouldnt rule it out for the track once ive gotten all the bugs worked out.

Vented hood and meth were definitely up there on my list of essentials. In the same mentality as you, Ive always just preferred meth in a boosted set up just for precaution and safety. Ive been in a couple blown vettes and my daily is a turbo car, Ill admit that I have always wanted a turbo vette so Im biased, but I just prefer a turbo car more as long as its setup properly.

I just did my introductory splurge last summer, was definitely fun and reliable and the car can really take an absolute beating. At the end of the day, it wasnt nearly enough for me so its time to really get into it.

I understand a blower could be cheaper way to the power but Im looking forward to the versatility of a turbo set up with a street tune and a kill tune for the track

Yea the more research I do the more it looks like it that will not be the route I go.

Stevie,

I had the C6 APS kit on my previous C5 Z06 and it really did spool that freakin' quick.
My car made 500 lbs torque at the tires by 3500 rpm or so, which is, to my knowledge, unheard of for a stock-engined bolt-on centrifugal setup.

I'll have to dig up the dyno sheet to see where the torque came on compared to stock.

Obviously a built engine with larger turbos would spool slower but a properly set up kit can be extremely responsive.

My experience of going from the stock turbo in my Subaru (full boost at something like 2500 RPM) to a bigger one (full boost at about 4000 RPM) led me to think that the evils of lag are greatly over-rated. With my current setup, the car is almost naturally aspirated when cruising at 2000-2500 RPM but all it take is a downshift to get into the happy range. Low power at cruise speed isn't really lag, it's just being in the wrong gear. :) If I'm driving for fun I just don't let the RPM drop below 4000, and when the RPM is above that full-boost threshold, the lag is pretty much imperceptible. It might not build boost as fast as I can stomp the pedal to the floor, but it's close.

That's with a 52 lb/min turbo on a 2.5L engine making about 375whp. So I assume that the same turbos on a 5.7L engine would be good for about 750whp with a lower boost threshold. And with newer turbos (GTX 3071 rather than my Subaru's GT 3076) the boost threshold might come close to 3000 RPM.

Just thinking out loud.... :)

People can mean different things by spool, boost threshold, lag...whatever.

As said....a log showing the time from when you go WOT ( at any rpm ) until it achieves desired boost is what I would refer to as spool.

Boost threshold would be more the rpm where desired boost is achieved which is a little different and very much load dependant.

Mine too can generate good boost at say 3500rpm in 4th or 5th gear if I go WOT...but both scenarios are fairly abnormal scenarios for every day driving, or indeed hard driving. But if I went WOT at say 3500rpm, mine would be lazy in terms of spool and probably would be a few seconds but it will achieve desired boost much faster in 5th with good load on the engine, than it would in say 1st gear with little load. But it'd already be accelerating hard in 1st anyway so it isnt a big deal.

If I went WOT at 3000rpm.....most definitely by time it was at 3500rpm, I'd have good boost available. But with larger turbos they just wouldnt be working that well in that area, and undoubtedly your APS kit would feel far far more lively as you note with far more torque even if our boost numbers might be the same and yours would be the much faster car in that area. Hence turbos need selected for the power/torque range you want, rpm range, driving style, power goals etc.

90% of the time I rarely go over 2000rpm, and could easily and briskly drive thousands of miles like that even despite mine being relatively slow spooling.

Clearly over 4-5000rpm is where it can all come very much alive, boost response, transients etc all improve greatly.

So again...spool instant ? like a light switch ? etc ? Maybe 0.2s...0.3..0.4 ? Instant to me literally means that. 0s.

Show a datalog of going WOT at whatever rpm until it achieves desired boost target. Whether from 2000....3000...4000rpm, etc
I've no doubt yours is very fast even at far lower rpm's than mine would ever generate boost...but instant etc ? No. Even the best OEM small turbo cars are not instant...but they can be bloody good and very fast.
A small turbo setup should still be able to manage 700 or so but make good boost from around 2000rpm or a little more. Something like that would feel superb for every day use and some racing as it'd be a torque monster to move you along effortlessly and for the likes of this thread, would be a good target to aim for.


But a blower car.....truly does feel instant just like a very responsive n/a build...except better.
Pretty much why I say the Vortech on mine felt more exciting, alive...as no matter where in the rpm it always had instant get up and go. Which is just different to any turbo setup. I wont say better or worse, just different because both are excellent

I recently did a Subaru here, with the latest turbo from Lateral Performance. Just a simple drop in replacement so easy install. Obviously had full supporting mods, engine was rebuilt anyway, forged rods/pistons, uprated valvesprings but still stock heads/cams, good quality FMIC, full fuel system etc etc.

Now I've done a load of these over the years with various engines, turbos, etc and as you say quite often a lot just dont perform until around 4000rpm or sometimes even later. But it's not a big deal really.

This car, just a regular 07 2.5 STI single AVCS was easily making 1.6bar boost by 3200rpm ! and although we don't do dyno's here, this car is easily making in excess of 500hp.
But the wide spread of power/torque because of that fast spool....it's just bloody superb everywhere ( but still not instant lol )
Yes I've done others that are faster with a lot more power etc but as an all rounder for a daily driver this was just bloody great.


But that's also why I'd say do not skimp on the turbos, especially with some chinese shite. They are such an important part of the build that a good quality item can make a huge difference always buy a reputable and proven brand name, and the best model your budget will permit within that.

One of the main reasons I love a turbo. The car will drive like almost stock when youre not in it and make long 4 hour road trips bearable

Budget controls "best setup". The more limited budget, the more you start having to make your own parts, you need a welder, fab shop, etc and the cost will have this sort of parabolic effect where it costs even more as you try to do more things yourself the right way with expensive tools and equipment factored in. Imagine having to buy a whole machine shop just to tool 1 engine over for 1 car, that would be far more expensive than buying a bunch of built engines done somewhere else. But then the where else becomes a variable all of it's own with it's own probability statistics for success that are now out of your control. So budget in this perspective reflects build control: How much control do I want or need to have over each aspect.

I will skip to the good stuff. Lets say you need 100% control, but also combined with low budget. It means you cannot buy your own machine shop to turn out an engine, and having 100% control means you cannot buy a built engine either. That limits us instantly to SBE variety so we start from there: find the best stock engine for the build that meets the budget. If engine budget is $500 you go for the 5.3L truck engine. If you have more you try to get an aluminum variety. Most stock engines stop between 800-1000rwhp so I wouldn't be thinkin about much more than 700 to the tires in a daily driver with some kind of budget SBE setup. Once you figure that part out the rest is easy: pick a cover that flows ~80lb/min and put a mild cam (228* @ .050 with less than .600 lift) and off you go with whatever you create, wherever you decide to put it.

"Lag" gets a lot of bad rap that we need to put into perspective. Most setups feature 'oversized' turbos because they are racing the vehicle in question. If you flow to around half of the compressor map, you are sitting right near the center island (a little to the right is...) Use a 'matchbot' to see where the engine combo lands, for example here is my 5.3 with the turbo I picked:
http://www.turbos.borgwarner.com/go/05M2G7

If I was racing the car this turbo would be terrible because it flows right out of the center island and off the map to the right almost immediately once it gets some boost in it. However, this is how the OEM typically size a turbo: peak torque of the engine is near the center island and the compressor runs right of it as it nears redline, falling off the map to the right. This is what happens when we size the turbo "just large enough to make the total desired power: 80lb/min giving us ~800 horsepower". Why the OEM does this is for a couple simple reasons: the first being that now the turbo's wheels weight is minimal and it will spool as fast as possible. The second is now the turbo will be most efficient during engine peak torque, adding to the 'surge' of torque midrange (often turbos are added to 4-cylinder and 6-cylinder engines which spend more time there in daily driver applications) and ensuring an efficient compressor when compression pressure is highest (peak torque region). There may be other reasons but we can take those that we already have and go to the bank: if you want the vehicle to drive like that, with powerful mid-range, fast as possible spooling, almost like an N/A engine quality, you would size the turbo the same way.

Lets look at racing again to tie this up. In racing the engine will not spend any time in mid-range. Even spooling up we would use nitrous and so forth to get it going and a large racing converter to blow through the mid-range and get to the peak power. So we size the turbo for that: we make sure it runs into it's center island during peak power, instead of peak torque like we wanted above for the street car. This way the compressor is most efficient during peak power region. It has "too much to give" more than we want. If you wanted 1000 to the tire in a racing setup you would buy a 1400-1600hp turbo and not use the right most portion of the map, this is how you would set the matchbot to choose a turbo.

1000-whp target and less => Go with supercharger POS or Centri
1000+whp and more => Go with Turbochargers

If your personality is thirsty for more power and participating in drag racing with targets in mind that require more HP and power every time to compete,,, definitely the turbo is your love.
I don't have experience with turbos yet but I was very happy with Centri's reliability (except F2 was aggressive) in past years making from 700 to 1100whp ( & now moved to Twins turbos seeking 1800+hp, build in progress)

It’s a 2 year old thread...