Thank you for this perspective. If I'm understanding you correctly, you’re saying that with heads/cam/tune less horsepower might equal or surpass the performance of a higher horse powered supercharged car? Hmmmmm I think I'm getting dizzy with all the different opinions out there. But that's what this fourm is for.

Thanks again

 

Spin, as Cell6ida already said, I appreciate your perspective on this subject. You hit the nail on the head when you said it depends on what you will use the car for. As you know, I have been trying to make the decision between H/C vs supercharger for months. This thread has been an excellent read and given me some clarity on the best choice for me.

 

Spin, since you used me as an example, there are two things I need to point out:

1- I left work one day, drove to the drag strip, and trapped 129. Full weight, crap in the car, street tires, etc. I didn't even change my tire pressures.
If you look at the very fastest heads and cam cars on this forum, the trap speeds are 130 and 131MPH for LS2, and 131 and 132MPH for LS3. The people driving those cars are arguably some of the best drag racers on this forum, they like to do it, they have been doing it for many many years, and they race a lot. And they did that on DRAG SLICKS. So, while I appreciate the flattering comparison, it is as relevant as me pointing out I've seen other supercharged cars run 13.X @ 11XMPH, and C6Z06s running 12+ second 1/4 miles. There are a LOT of factors associated with it, and comparing my handful of trips to the drag strip in my daily driver with the fastest heads and cam cars in this forum running drag slicks is not a good comparison.

2- I did blow my engine. I've been one of a few people who managed to do that to a bolt on supercharged car. I have seen at least as many heads/cam cars break because of broken timing chains, broken valve springs, bent valves, hollow stem valves that break off and fall inside the combustion chamber, bent pushrods, and all of the other 1000+ reasons why, for instance, when GM wants a more powerful engine, they either make it BIGGER (LS3, LS7) or go FI (LS9) as opposed to just slapping on a bigger cam. Before I popped my engine with 65000 miles, I had done just about every single form of drivetrain abuse to the car that one can do. I drove that car to well over 200 miles an hour, sustaining full throttle for 48 seconds, I bounced the rev limiter almost daily, I did more pulls to 180MPH than I can remember, and it never as much as threw a check engine light. I have little doubt that an agressive heads/cam setup would have suffered valvetrain failure under similar conditions for that long.

The bottom line is that nothing modded will be as reliable as a stock engine, otherwise it'd have come that way under warranty from the manufacturer; we make compromises when we change things, and my reasoning is if I'm compromising for power I want as much of it as I can... I wholeheatedly understand the guys who like to kee it N/A. It is not for me, I'd NEVER put up with a big cam, but if it makes you happy, GO FOR IT, that's all that matters in the end anyways: when you get in your car and fire it up for a drive, does it make you smile? I'm as happy with mine today (blown engine at the shop and all) as I was the first time I drove it. If you can get that by keeping it stock, or doing bolt ons, or going H/C, its all good
Either way, I just wanted to clarify those two things.

 

Nice post!

 

yes nice post Spin and Powerlabs. These guys concisely put into words what I try to express and give a mechanical reason for it at the same time.

Spin said, "off boost rpms and shift boost pressure losses". 8 words said a lot right there.

PL said, "The people driving those cars are arguably some of the best drag racers on this forum, they like to do it, they have been doing it for many many years, and they race a lot. And they did that on DRAG SLICKS. So, while I appreciate the flattering comparison, it is as relevant as me pointing out I've seen other supercharged cars run 13.X @ 11XMPH, and C6Z06s running 12+ second 1/4 miles. There are a LOT of factors associated with it, and comparing my handful of trips to the drag strip in my daily driver with the fastest heads and cam cars in this forum running drag slicks is not a good comparison." Well said too.

 

Your statement, 'does your car make YOU smile' is the bottom line.

 

 

 

I was making a HP comparison and it makes little difference since as you ALWAYS point out, your car makes more HP and TQ than even an N/A stroker at all RPM's.

Trap speed doesnt change as you change tires or gears, ET does. C6Dvl running a slipping clutch and dead BFG tires ran a 11.8 at 128 and then a 10.8 at 128 when he changed to new tires and a new clutch. If you ran slicks or any tires you would trap the same. Trap speed for anyone in the know on drag racing is a true reading of the car's average output power.

So when I say a little 6 liter such as Dennis' 2005 A4 running a 130 trap speed or a 6 liter such as Brachiole's 520rwhp LS2 running a 134 trap speed at that low power compared to your car's 590rwhp+....its still slower than the trap speeds of these N/A cars by HP. You should be at 139 like a 600rwhp stroker that runs 139 trap speeds if HP is HP. You did point out that your kit makes more HP and TQ when stroker dyno sheets were shown. The a6 in my fist post was driven by Doug with ECS' drag radials so I would think its pretty optimum. It was 660rwhp on an A6 compared to Subfloors sub 600rwhp car running 5mph faster. Apples to apples?

Again, since you ignored it, the big cam drivability BS you are saying is 100% false. The current cam only LS3 AndrewZu has trapped 130+ with just a cam and he has a full weight car. Its a 230 cam and runs like stock with zero 'big cam issues' as you say. He has no ported intake or TB and no UD pulley. Its a 1500 dollar mod plus a set of headers. This is 0-130mph in 11.2 seconds for a cam without heads. The current LS2 record cam only is also 130mph (Dennis) and the current LS2 C6 record (thats LS2) is brachiole's H/C car running 134mph at 520rwhp. Number 2 on the LS2 C6 is also a H/C LS2 also at 134mph. The two fastest LS3's are Cartek and C6Dvl (ECS) at 132. The point is HP for HP N/A is faster. Trap speeds tell the same story regardless of tire and in fact, MPH is actually HIGHER if you dont hook.

I can go on with stroker numbers (also N/A) to show that 600rwhp makes 140 trap speeds from N/A and I have never seen that from 600rwhp on an FI car.....not even a turbo car. I think for a turbo car 650rwhp was close.

I also dont hear much from the H/C crew about cracked pistons or fuel system issues. Its very rare compared to the FI section where the number one reason for a stroker is a blown motor.

Anyway, you werent singled out, I was using you as one of 8 cars in the comparison.

A tuner's position on the facts:

 

So far as I can surmise, the vulnerability of N/A HC set-ups is USUALLY with the springs, whereas with the S/C it's the pistons/bottom end.
Many thanks to Spin, PL and Max for your input. All your info leads one to an understanding of the complexity of a mod decision. Thanx for sharing.

 

So basically the MPH is lost during shift points with the manual due to pressure losses? Other than that the only logical explanation is that the N/A setup makes more average hp, with much less peak hp, over the rpm band in the midrange than an FI setup, which as we all know is typically not the case. I would expect, as stated in your post, for an auto to have minimal pressure losses between shifts. So are we saying a 500 hp N/A Auto car will have similar (2-3 mph difference) traps as a 570 whp F/I Auto Car?

 

If I am following Spin correctly, I think the answer is yes.

 

Interesting read,
F/I power does generally need more "dyno power" since what the car makes on the dyno, is not a true reflection of what it makes after the IAT's have raised going down the track. Also, most people just discuss peak numbers, but the key is look at the average HP during the RPM band in which it goes down the track. N/A cars generally have less of a peak to the graph, so the lower number people focus on from N/A, can really end up closer to the same average HP. However the driveability is like stock from F/I, and the power is so easy to raise.
N/A is just mean, like a Harley, and does not have the IAT issue's that F/I brings, but comes with the lope, and usually a loader exhaust along with a little smell to the exhaust assuming the cam is a decent size.

It's a personal preference that has no "wrongs" unless you have specific usages in mind. If you are a road racer, we would never direct you to any F/I since most of road racing is combating temps. F/I will do that more then N/A, but we do have plenty of guys out there on the road course with F/I. For the average street/strip guy, we direct them towards F/I because we have found that people almost always want more power down the line, and F/I makes that so easy.

Once you do a H/C our fully built engine, within reason, that's it. With F/I you can grow with it if you like. We have many, many customers who come in and start with a base SC kit on a bone stock car. A year or two goes by and they are back for headers, and now with the added power it's like a shiny new toy again. Then a year or two down the road we might see them back to add meth injection, and again with even more power added, now it's a shiny new toy again. I have found our customers like that they can go in increments and keep enjoying the build of the car.

As you can tell, I'm a little biased towards F/I for the street, but I do own a snotty N/A car too, they are both great, just worlds apart really. We have several bone stock-no cam swaps-unopened 100% LS2's that are making 750-800rwhp, and trapping over 140mph. The gas mileage is great, and runs like factory. That's hard to not to look at that as appealing IMHO.

Good luck with whichever direction you choose, feel free to call if you have any questions that we can help with.

 

In answering I was limited the result to what you get from a basic H/C install compared to a base S/C kit for cost comparison. A 750-800rwhp FI car is far from the 6500-7000 dollar cost and is going to incur the meth syetem, fuel system upgrades, and shortblock with at least a cam install--and forging getting you well near the 20k mark installed to do that. Yes its a path to upgrading just as a H/Cam install is part of the same upgrade path as I did on my car.

I had a small 228 cam and LS3 heads and then added your 2200 kit on top of that.

I will put the money on a small to moderate cam and trick flow heads to a base s/c kit installed so for the same 6000 to 7000 bucks the car is going to be just as fast if not faster with the H/C install first.

To those inscreasing the boost and using a restrictor plate as the ECS kit does you can come pretty close but I have yet to see a base kit on its own top the four best H/C installs for factual performance. The cams setting these 132 to 134 trap speeds are 234 cams and do not buck and surge as the base kit owners would have you believe. If there is such a kit (on its own with no meth injection and fuel system upgrade) I have asked for the time slips.

I am well aware that most base kit owners under 600rwhp think they can beat a H/C car in a roll on. Anyone in the NE wanting to try it can be arranged to try against a car that traps 132. This is not an invite for a street race but rather a closed course. Spare me the talk and send a PM if you will race. I've owned and built both and know the H/C is faster up to 600rwhp on an FI car.

I'm not bashing FI. I own it and know it can be built to far exceed H/C but it isnt happening for cost of a H/C build without a fuel system and meth injection. Just about any FI car running at 700rwhp has a cam installed too.

 

I think the two A6 cars driven by great drivers and both running the optimum tire, best exemplifies the difference and dismisses driver skill.

 

I respectfully disagree with you Spin on that. Skill sets are important. For example, Chris(aka Thesubfloor) can drive and I cannot--No amount of HP can make that up. Oh well this thread has had it for me. I learned a lot--Thanks to all of you guys!

 

Dude, Doug from ECS was driving the other A6.....He is as good as any driver. I think he is a match for Subfloor. To further illustrate how trap speed is not so ET and driver dependent, When Doug drove Ed's (C6DVL) car to a 10.8 at 128, Ed himself drove it to an 11.1 at 128. The same car with the old clutch and worn drag radials was 11.8 @ 128.

Trap speed is a measure of average power a car makes. Cars with massive peak dyno power dont translate into higher trap speeds proportional to the peak number.

As already stated by 2 tuners in this thread, FI power needs to be higher to run the same trap speed. One says its due to higher IAT's and the other lends more of this due to lost boost pressure between shifts which doesnt show on a dyno since its a single gear run-up.

In a phone call with Sam powerlabs, his own personal assessment was that the IAT rise from running full boost in 4 geats heat soaks the intercooler which doesnt show on a dyno and is responsible for lower track performance. I wish I had recorded that call because it began with, "Hey you were right about FI cars not being as fast at the track. I logged the IATs and saw it myself that 4 gears of boost heats the air."

Now if your race of choice is for two cars to line up on the hiway in 4th gear and run it up to redline, I think the 600rwhp car will win. As you add more gears to this race or do multiple races, its likely each subsequent run will be slower because the intercooler will be hotter on each run than the prior one. This is where meth injection translates into massive gains because it lowers IATs a lot. Shifts will still induce lost boost pressure for manual cars.

Another thing to look at which I did was to look at 1/8 mile performance and 60's for the BASE KIT. Far too many FI car owners dont regear because they (mistakenly) think its all wheel spin and as such their performance in the first two gears is a far cry from a geared H/C car. In JoeG's cam only geared car he logged 0-60 runs at 2.7 seconds.

But the gear thing is another thread and I'm not going there today.

I am getting hate PM's from FI owners....I am talking about a base kit install against a similar cost H/C install. I know what meth and fuel system upgrades will do for the car along with gears and a cam.....I own all those mods.

 

any videos of a 500rwhp h/c vette vs a 600rwhp sc vette?


how does a blower cam affect average power in a sc car?

im looking to build a 650rwhp vette using 8lbs and a blower cam + supporting mods, i want to know how im going to perform against z06s (including stock, bolt ons, h/c) also zr1s

 

Spin......Thank you much for your experienced input

 

Just about any cam that is less than zero degrees overlap will produce 70 more rwhp. I made 704rwhp at 11psi with a 228 cam and box stock LS3 heads that lower your compression. Another local with a cammed LS3 made 716rwhp with about the same boost. I made 471 through 4.10's on this H/C package before the supercharger.

The ECS kit allows much more power under the curve because the restrictor plate lets you have the 8psi limit over 5500rpms but gives you the bottom end HP/TQ of a kit spinning the s/c to make 12psi. This gets you 4psi at 3k and 7psi at 4k rpms but isnt dangerous up top from too high a boost.

At 650rwhp I would consider meth injection mandatory. 8psi and a cam in an lS2 will hit just about your goal with meth. it will be about 620rw without it.