GT500 in the 8's

[Paul]

It may be a bit exaggerated, however, it's the same correction factor that all dyno's use to correct numbers. There is no forced induction vs. N/A correction factor, unfortunately. Again, we are more interested in the curve of the graph than final number it puts out. Compared to other twin turbos, and single turbos the area under the curve in the graph is great, and that's where the benefit of the compound boost setup comes in, hence my willingness to post a graph that's uncorrected showing 970hp, because it's not about the peaks #'s. Having said that, gains of 200+ hp from a correction factor occur with all forms of induction, forced or not.

While the area under the curve is certainly impressive, and the combination no doubt produces excellent results - the correction factor is still unreasonable IMHO. A forced induction car will not make 20% more power at sea level than at 6000 feet because the compressor will compensate (to an extent) for the loss in atmospheric pressure and air density.

That's why Supra's get a bad rep, because usually their power isn't as present under the curve as it is at the peak, so they only have a ridiculous amount of power for a short time. That's what we were trying to avoid.

I'm not a Supra fan.

Superchargers are affected just about as bad as N/A engines because their speed is limited to a certain amount by a pulley, but even still, dyno's will show 120-180 rwhp gains with the correction factor. The correction factor for this graph isn't that outlandish, especially when, in our experience, moving down to a lower, more dense air condition usually increases boost 1-3 psi, which would make up the power shown on the corrected vs. non-corrected graphs when combined with the increase in air density.

I disagree to an extent. The compressor (driven by a belt or an exhaust turbine) will be able to compress the intake charge to a certain level of restriction (boost level) and the correlation is certainly not as relevant as the fans of correction factors such as these would lead you to believe. Further, 1-3 psi in gains at sea level do not equal 200 horsepower IMHO. Why would an increase in boost of ~3-10% result in an increase in horsepower of ~20%? *edit* This seems to be especially true when evaluating this with boost pressures approaching two bar. Forgive my use of an Economics principle, but I would expect some "decreasing marginal utility" as such high boost pressures in terms of horsepower-per-psi.

It is a commonly accepted principle that atmospheric pressure is less relevant to engine performance in boosted applications than naturally aspirated. While correction factors are all well and good, readers should always take them "with a grain of salt" since often times the uninformed may take the "big number" as gospel and fail to look at the math behind the number.

Paul.

 

[Steven]

Through an auto

Interesting for all you clutch/penis compensating people.

autos for drag racing, sticks for having fun. I wouldn't trade a stick for an auto in a road course, but on the drag strip, auto>stick

 

[Hellion94]

While the area under the curve is certainly impressive, and the combination no doubt produces excellent results - the correction factor is still unreasonable IMHO. A forced induction car will not make 20% more power at sea level than at 6000 feet because the compressor will compensate (to an extent) for the loss in atmospheric pressure and air density.

The correction factor may be unreasonable, and I never said that it wasn't. However that doesn't change the fact that it is still the standard used by everyone else. Because of this, the numbers that are generated by that factor are the numbers that everyone is used to hearing, so to avoid any confusion, or having to state that a different correction factor was used everytime the number is repeated anywhere, we use the standard factor.

I'm not a Supra fan.

That's great. I never said you were. I simply used a commonly recognized example of power vs. rate of acceleration.

I disagree to an extent. The compressor (driven by a belt or an exhaust turbine) will be able to compress the intake charge to a certain level of restriction (boost level) and the correlation is certainly not as relevant as the fans of correction factors such as these would lead you to believe. Further, 1-3 psi in gains at sea level do not equal 200 horsepower IMHO. Why would an increase in boost of ~3-10% result in an increase in horsepower of ~20%? *edit* This seems to be especially true when evaluating this with boost pressures approaching two bar. Forgive my use of an Economics principle, but I would expect some "decreasing marginal utility" as such high boost pressures in terms of horsepower-per-psi.

It is a commonly accepted principle that atmospheric pressure is less relevant to engine performance in boosted applications than naturally aspirated. While correction factors are all well and good, readers should always take them "with a grain of salt" since often times the uninformed may take the "big number" as gospel and fail to look at the math behind the number.

Paul.

I stated that the combination of a denser air charge (due to the lower elevation) combined with the increase in boost is where the gains in power come from:

moving down to a lower, more dense air condition usually increases boost 1-3 psi, which would make up the power shown on the corrected vs. non-corrected graphs when combined with the increase in air density.

I didn't reply to this thread in order to get into a big pissing match with you Paul, and I'm certainly not making outrageous claims or inflating numbers. Those are the numbers that came off the dyno. Think we are the first people to ever use the SAE factor on a turbocharged car on the dyno? This is why I replied quickly with your request for non corrected numbers. I showed you what it "actually" made. Believe me when I tell you that we all fully understand the math behind the numbers here. It is, after all, what we all do for a living, and I'm telling you the same things that I would tell any customer that called the shop, or any person that I would bump into at a race or on the street.

You may disagree with it, as many others do, but until there is an agreed upon, turbocharger correction factor for altitude, we will continue to tell people the numbers that the dyno operators give us, because, well, that's all we can do. If we just stated uncorrected numbers, the issue would then be what it made corrected for altitude anyway, so why do we just quit this pointless B.S. as it's not helping either one of use, nor is it relevant to the original topic.

 

[Paul]

It was never intended to be a "pissing match" Hellion, nor do I see anywhere where I indicated it should be. I'm simply stating my opinion why the numbers appear a bit inflated since part of the discussion in this thread has been turbo 5.4 vs turbo 4.6 numbers, as it were.

Further, I don't see any "hurt" in explaining clearly why people, in general, should be somewhat skeptical of dyno numbers.

While you and many others certainly may use corrected numbers, I think it that ANY dyno numbers given in any circumstance should include BOTH the correcated and uncorrected numbers, and the correction factor being used. It think it paints a more complete picture. That is all.

I apologize if you think that this discussion is somehow non value-added "pointless B.S."

Paul.

 

[Steven]

I think the point is to be able to be on the same basis as everyone else paul. It's not so much whether it is the correct correction numbers, it is just so that hellions numbers will be comparable to any other companys that use that correction factor. As to whether they are correct or not, I honestly am not technical enough (not yet anyway) to fully understand how it works, and what is reasonable and unreasonable, but the point is, is that those numbers are on the same playing field as HP's, and any other performance company that uses said factor.

 

[Paul]

Not really. Let's say you took that exact same car, controlled ALL variables correctly, and dyno'd it at two facilities. The first facility is at sea level and the second at 6800 feet. The correction factor used at the second facility would inflate the power number generated higher than the hindrance provided by the higher altitude/lower air density.

In other words, no - they really wouldn't be the same.

 

[Hellion94]

It was never intended to be a "pissing match" Hellion, nor do I see anywhere where I indicated it should be. I'm simply stating my opinion why the numbers appear a bit inflated since part of the discussion in this thread has been turbo 5.4 vs turbo 4.6 numbers, as it were.

Further, I don't see any "hurt" in explaining clearly why people, in general, should be somewhat skeptical of dyno numbers.

While you and many others certainly may use corrected numbers, I think it that ANY dyno numbers given in any circumstance should include BOTH the correcated and uncorrected numbers, and the correction factor being used. It think it paints a more complete picture. That is all.

I apologize if you think that this discussion is somehow non value-added "pointless B.S."

Paul.

I'm sorry Paul, it's just difficult to judge emotion/inflection with text only, and I suppose I'm used to every other internet warrior who feels they need to prove everyone wrong.

I didn't feel as though the things you said were in spite, I just didn't want this to get to that point. We can argue back and forth all day about those things, and that's all I was trying to avoid. To a certain point, because of what you stated (the not to trust dyno numbers part in particular) this is somewhat pointless. All in all, there is no real way to verify that any dyno is putting off actual numbers, because it after all is simply based on a calculation, and there are many other variables that will make a difference in power numbers and performance, such as load, which can't be adjusted on a DynoJet, which is what we used. So in summation, it would all be B.S. at a certain level, just because there's no way to substantiate the numbers that a dyno displays realistically.

I meant no harm with what I said, I just didn't want this to become a thread about our dyno numbers and what not. I just came on to answer a question/correct a small bit of misinformation.

Everything's good. You know I have respect for your knowledge and opinions. :happydrunks:

 

[Paul]

C'mon Hellion - you know I don't have any e-feelings. I had them amputated at a young age.

No worries.


Oh, and that amount of power is obscene. The fastest car I've been in made 725 rwhp and trapped 141 mph. I thought it was a goddamn rocket so I'd probably soil myself in that blown-TT-cobra.

Paul.

 

[Steven]

once again proving my ignorance paul.. lol. Like I said, learning here.

 

[Hellion94]

C'mon Hellion - you know I don't have any e-feelings. I had them amputated at a young age.

No worries.


Oh, and that amount of power is obscene. The fastest car I've been in made 725 rwhp and trapped 141 mph. I thought it was a goddamn rocket so I'd probably soil myself in that blown-TT-cobra.

Paul.

Haha I know what you mean.

Funny story about dyno's and such since we are on the topic. When we completed our Twin Turbo Outlaw 10.5 car, this one:

We took it to the dyno to tune it. Well we get the base tune in it, getting it idling and starting good, and figure "Hell let's make some power." So we dial it up for 23 lbs. of boost and let it rip, and it made an astonishing 830 rwhp. Out of a twinn 88mm turbo, 440 inch windsor.

Naturally, we were like, what the hell? Everything looked good though, so we let it go and decided it was fine. We took it out testing a couple weeks later and it ran good, so we took it to the Street Car Supernationals in Las Vegas, and it ran A 7.24 @ 3100 lbs...

It was just due to the way that the dyno load operates. Turbo's thrive on load, and if a car is so powerful that it spins the roller quick enough, the load dissapears, and the turbo will stop making power. It'll still be spinning fast, but there just won't be any power there. That's why the turbo cars always feel stronger on the street than their numbers usually reflect.

It's weird stuff sometimes.

 

[Passenger]

more than 1,000 rwhp in the twin turbo/blown cobra

http://www.musclemustangfastfords.c..._compound_boost_2003_mustang_cobra/index.html

according to the article, the turbos made 27 psi and there was a total of 44 with the addition of the blower. compare that to the twenty something from the turbos on the shelby with close numbers...

i didnt know the terminator blew up, must have been after this article was printed. insane cars/numbers either way. and they did say that the 03 engine was stock

Exactly. Not real sure why Javi thinks thats bad though. :dunno: That Cobra from Hellion had massive fuel system upgrades, just like the GT500. Both completely stock internally.

5.4 vs 4.6 ? hmmm

and the 4.6 made almost the same power. :rolleyes2:

The same power with DOUBLE the pressure blowing through it. Barking about displacement vs power is a Honda thing Javi.

 

[Javi]

K :thumb:

 

[5.Woahhh]

Who cares about dyno numbers. Their just good for tuning. The time at the track is what matters.

I was at a car show and tho guys had matching GT500's putting down 700+ Or thats what their little banner said. I was talking to a guy who was racing his GT500 and he was like, "I'm not even blown and I will line my car up and race them. I don't care about the numbers."

 

[1996mustangGT]

What engine does the ford gt have in it?

same engine....

5.4 4v, supercharged

I was just up at Evo Perform...the car was sitting outside with 8.99 on the windshield I believe...lol

different block j-man.
iron for gt500
al for GT.

i love these intelligent disscussions that i hopelessly try to follow.

i know i should have paid attention in fluid mechanics :hammer:

 

[Hellion94]

Who cares about dyno numbers. Their just good for tuning. The time at the track is what matters.

I was at a car show and tho guys had matching GT500's putting down 700+ Or thats what their little banner said. I was talking to a guy who was racing his GT500 and he was like, "I'm not even blown and I will line my car up and race them. I don't care about the numbers."

GT500's come with superchargers... So how is he not "blown"?

The same power with DOUBLE the pressure blowing through it. Barking about displacement vs power is a Honda thing Javi.

While this is a valid point, it is important to remember that all boost is, is a measure of restriction. As weird as this sounds, Boost isn't what makes horsepower, it's what forcing that amount of air into and engine allows you to do that makes power, i.e. put more fuel into the engine.

Any given engine can only flow so much air, and no more - no matter what. When this point is reached, pressure begins to build up, which is boost. By adding more boost, all you do is increase the rate at which the air enters the cylinder, possibly allowing more air into the engine. However, at a certain point, it doesn't matter how hard to you push the air, only so much will go in, and boost begins to make no difference.

Case in point - With turbo's in particular, there's an efficiency range that the compressor wheel possesses. this is the point at which the wheel moves the largest amount of air at the quickest rate. Let's say that this point occurs at 22 psi of positive manifold pressure. Now, let's suppose that we get power hungry and really want to turn it up, so we crank it to 28 psi, and add fuel, and pull a degree of timing (the usual "safe" approach to an increase in boost). We run it on the dyno again, but don't really see much of a power gain. this is because we have already reached the efficiency range of that turbo, and have now surpassed it. Even if we go back in and make the tune more aggressive, we may only see a 15hp gain from 6 extra psi.

In a compound setup like ours, where the boost is very high, we run into this same issue. The engine can only move so much. That's why I stated before that the power numbers we made at 44 psi could easily be duplicated at a lower boost pressure if the tune were spot on, because that much boost simply isn't neccessary for that kind of power. Also, when looking at a compound setup, it works best to forget about the final boost numbers, and look at the individual numbers. On our car, we ran 10 psi from the supercharger, and 27 psi from the turbos. When you go back and look at the graph, the first section of the graph (before the turbos came on line) looks like it would if the car were just a 10 psi, roots blown motor - which it is. Now if you look at the second leg of the graph, it looks like a car that's running 27 psi from twin 66mm turbos - which it was. That's because the power will be dictated by which power adder is more efficient at the time. In the beginning of the pull, there's no boost from the turbos, so the supercharger is the more efficient, and the power and torque reflects that, but when the turbo's come into boost, they are the more efficient, and more powerful, and they take over.

It's a weird concept to understand, but just remember that a lot of times, boost pressure is just a number for reference, and not what's actually making the power.

EDIT: Here's some more info on what it is that I'm talking about.

http://www.theturboforums.com/projectcar/BigJay/bigjayboost.php

 

[jfor441]

Who cares about dyno numbers. Their just good for tuning. The time at the track is what matters.

I was at a car show and tho guys had matching GT500's putting down 700+ Or thats what their little banner said. I was talking to a guy who was racing his GT500 and he was like, "I'm not even blown and I will line my car up and race them. I don't care about the numbers."

GT500's come with superchargers... So how is he not "blown"?

I just read that and was about to ask the same question LOL

 

[Black97GT]

The same power with DOUBLE the pressure blowing through it. Barking about displacement vs power is a Honda thing Javi.

Wow I cant agree more with that. Some clown came on my local forum and was like "I only got respect for cars with 50hp or more per cylinder."

I lolled.

 

[5.Woahhh]

Who cares about dyno numbers. Their just good for tuning. The time at the track is what matters.

I was at a car show and tho guys had matching GT500's putting down 700+ Or thats what their little banner said. I was talking to a guy who was racing his GT500 and he was like, "I'm not even blown and I will line my car up and race them. I don't care about the numbers."

GT500's come with superchargers... So how is he not "blown"?


I ment factory wise. The other to cars had a KB and Saleen SC's. Sorry for the confusion.

 

[Hellion94]

I ment factory wise. The other to cars had a KB and Saleen SC's. Sorry for the confusion.

Ahhhh, I gotcha. :thumb:

 

[5.Woahhh]

I ment factory wise. The other to cars had a KB and Saleen SC's. Sorry for the confusion.

Ahhhh, I gotcha. :thumb:

Whats the use of all that power if your not going to use it? Just to brag?