DDSLT5

RED99

Well, maybe I shoudln't use the word "suck". I meant how much HP the compressor draws from the motor. Turbos don't draw any power to turn it, but they build back-pressure in the exhaust system which in turn tax's the power. If you put a 8-71 on a stock LS1 motor, the motor wouldn't have enough power to spin the blower to make any boost because the mechanical efficiency of the blower itself takes more power to spin it, than the motor puts out on its on. Put it on a 427, and you might get 5-6 pounds of boost. Put it on a 454, then you might start seeing 15+. It's almost impossible to measure how much HP it takes to spin a 8-71, but 400 HP is what you hear most people will say. That's why you won't never see a 8-71 on a small block.

So whatcha got in that boat? A close friend of mine that died from cancer a few years back had a 55 chevy that we all helped him build that had a 462 ci Blown Alky motor with a 8:71. Steel bodied car that weighed right at 2000 pounds with the big block. It was called GROUND POUNDER, and it would do just that. Sounded just like a AA/ Funny car. IT was BAD ***. Too bad he died and only got to run the car twice before getting too sick to drive it anymore.

Warp Factor

Thanks, DDSLT5

vetterdstr

I installed my first S/C F/I setup in the 99 C5 almost 3 years ago. Once I stepped on the gas pedal I was hooked!! After many re-builds on my system I am glad I stayed to this point. With so many new systems coming out today, it would be hard to choose... ECS/Andy's S/C ??? STS TT ?? Each has its place and each will do the job. You have to ask yourself what YOU want in an F/I system.

Example... the NHRA guys do not use Turbos to power those funny cars... but some Le Mans cars do.... So its up to each user to decide it 600 RWHP is better under the TT or S/C label.

ching.. ching...

VR

Warp Factor

Buddy, I'm guessin' you haven't been on for a few days. A lot's gone down. Info on the boat is back in the thread.
Seen a lot of 6-71s on small blocks, and a good number of 8/71s. No problem spinning up either one on the bench with a drill motor, unless it has "interence fit" teflon tip seals.
The major drag comes from when you use it to compress air, as with most air compressors. It's work to compress air, and power has to come from somewhere. But no problem getting 20 lbs boost on a 283 cubic inch drag motor with an 8-71.
As noted earlier in the thread, 400 horse might be an accurate figure for blown alcohol or fuel with high levels of boost. Otherwise, it's a lot less. Roots blowers will never be the kings of efficiency, but they're reliable, look cool, and they're cheap.
Thought about putting one on my C5, but it would sit really high, and I could imagine myself getting tickets for obstructed vision. Even went so far as to see if ECS had a manifold. They referred to the GMC as a "classic" or "retro" blower, or something like that.
Guess that pretty much sums up their opinion of roots styles.
I've pretty much shot my wad on that one. Go back in the thread, doesn't bear repeating.
HOWEVER, I've got an ace up my sleeve if anyone wants to go back at it.
May have had nothing to do with it, but that's one reason I don't run leaded race gas any more. Toxic as he--. Might not kill you right away. Starts out by making you really stupid. Some guys have brains to spare, but I don't have much margin.

Devil Dog

With two identical engines, runnnig the same boost pressure, a turbo will clean a blowers clock, and lay down about 100 ft.lbs. more torque.

blu00rdstr

Do you have examples, or is that just an opinion?

Jesse_Boyer

Does anyone have the "Boost Bash" article that Hotrod did a while back? They compared the three styles (centrifugal, turbo, roots) on the same motor and I believe that was the outcome. I, however, could be mistaken

I know there were two parts to the article... we need to find that in PDF

Devil Dog

Yes, in the Muscle Mustangs & Fast Fords mag article "Boost Bash" the turbo dominated all blowers (Kenne Bell,Vortech,Eaton) included in the shootout on the same engine with the same boost.

"Run at 11 psi, the turbo kit pumped out 750 hp and 679 lb-ft of torque, bettering all three of the superchargers [Vortech, Kenne Bell and Eaton]....once the tach needle swung past 3,600 rpm, it was all turbo. How does an extra 178 hp and 154 lb-ft. or torque sound? While the turbos were down by as much as 100 lb-ft at 2,500 rpm, they quickly made up for lost time by eclipsing the Eaton and producing the most impressive post-4,000 rpm power curves of the bunch." - Richard Holdener - MM&FF, December 2004

The article is located here: http://turbochargedpower.com/magazine_articles.htm



Also, I and a friend had 1994 stock 5 liter Mustang Cobras, he opted for a 8 lb Vortech kit, and I went with a Incon twin turbo kit, he ran 8 lbs. and I ran 7 lbs, I covered him by a easy 100 ft.lbs of torque, and I also made 430 rwhp to his 360.

Pakisho

Nah, he's right, for the most part. I believe it. Turbos are bad buggers. But I prefer blowers.

vrybad

All comes back to goals.
Turbos will usually make more power than blowers in most streetable applications, but I'd really rather have that low-end advantage of the blower setup.
A 100 lb-ft torque deficit is HUGE at 2500 rpm, and on the street, where most of us use our cars, who spends most of their time over 4000rpm anyway?
Don't get me wrong, I'm a former turbo guy(3000 GT VR4, 538awhp, 502awtq, 93 octane) and were it not for the additional expense and complexity of packaging, I'd be truly singing the turbo praises once again.
Back to the original question, 600 S/C or 600 turbo, I'd say it should be very close, with a slight advantage to the S/C car for most street driving situations.
I could be wrong, so we need a couple of you turbo and S/C guys to step up, with similar numbers, and take it to your local "test area" to find out.
Don't keep us waiting, now!!

2MuchRiceMakesMeSick

Well dont hold back on us. Lets hear it.

mdhmi

Low end. lol. I know you aren't talking about a MagnaCharger because those don't make 600 rwhp.

A centrifugal blower is *NOT* going to make more low end torque than a turbo setup.

Mark

Warp Factor

OK I'm going to call this "The Proof is in the Pudding" argument.

I decided to run the thread by an acquaintance who is a mechanical engineer by profession, and also happens to hold 5 East Coast Timing Association records on turbocharged bikes for the “Maxton Mile”, which is a standing start mile.

In my mind, the most impressive of those records was in the Streamlined Blown Fuel category. Why? He did it on GASOLINE (not fuel) with a NON-STREAMLINED, frequently ridden, turbo STREET BIKE!
I'm pretty sure the "blown fuel streamlined" was set on his first attempt.
He seemed to think that the notion of the turbo having little or no parasitic drag, and being run mostly by energy that would otherwise be wasted was “balderdash” (my choice of words).
Care to have your "experts" weigh in?

That said, the guy really doesn't want to get involved in this discussion. He burned himself out on the bike forums arguing things like this, and decided it was a waste of time. I think that's one reason he decided to go out and set some records instead.

Here’s the bottom line as I see it:
In order to support the notion that a turbo is largely powered by otherwise wasted heat energy, rather than compressed air provided by the engine at the cost of drag, you would need to show a temperature drop across the turbo which is:
Not caused by the inherent temperature drop due to expansion of the gasses as pressure is reduced across the turbo. In other words, a heat loss greater than if the system was run on just compressed air.
And a heat loss which is not due to heat transfer to the gas enclosure (plumbing, turbo housing, etc.)
Then we could say, "Where did that heat go? Hmmm, must have been converted to mechanical energy to run the turbocharger."
Can anyone do this?

Warp Factor

Come on, guys, it's been over three hours, and nobody's flamed me yet.

Ol' lady's having a good day, so how am I supposed to get my "conflict fix" unless someone comes on a tears me a new one?

I'm so desparate I might have to do it myself.

blu00rdstr

I'll be the devils' advocate. Air conditioners are heat pumps. They transfer heat through the pressure differential of compression and expansion.

A turbo is powered by pressure differential...is there is a pressure differential before and after a turbo. The bigger the downpipe, the less pressure there is after the turbo, the bigger the boost.

Devil Dog - Good article. I wish it has a centrifugal vs. turbo graph.

Skunkworks

Here’s my .02 – look at RWHP gain per pound of boost. Turbo can easily be in 27-33 RWHP per pound area (yes it tapers of the higher you go). Then look at superchargers 22-29 RWHP per pound.

Why the lower numbers? Numerous reasons but mostly RPM in the case of centrifugal designs. You have packaging constraints that limit wheel size and mechanical power transmission limits. So you are forced to run wheel at lower tip speeds. You could get 78+% efficiency if you can crank wheel in excess of 1400 ft/sec, hell I have seen wheels that are 85+%, but you could not build it at an affordable cost.

I have always said turbo is not free, but will admit generally more efficient unless losses are reduced on supercharger considerably.

With that said you have to look at the whole package, fitment, kit cost and installation cost, then make up your mind.

Mike

Warp Factor

Good responses, both of you guys.
I'm afraid we might be basically on the same page though.
I was really going after the guys who said things like,
"A turbo doesn't take any engine horsepower to run. It's powered by exhaust heat that would otherwise be wasted."

Good point about typical horsepower difference per pound of boost between superchargers and turbos. I'd never heard the reason for it explained that way before.
Skunkworks, care to venture a guess on how much "otherwise wasted heat energy" contributes to driving the turbo? (No, it's not a trick question, and I don't think I already have the answer, I'd really like your opinion)

It's a tough day for a conflict addict in need of a fix!

DDSLT5

I doubt anyone really feels that the power generated by the turbo is truly 'free'. This is an outdated view - most know that there is some drain with the turbo. If they don't know this, then they are quite out of touch.

#001 2001 Z06

Agreed, gentlemen.

I had significant debate a few months ago on this. I finally told a few guys, if they made anything that made truely free power to let me know and fast.