Ajax

The answer to omicron's question is simple. The answer is "it depends."

Omicron

HUH?

Bob, I'm talking two identical RX-8s here. One guy buys a Greddy Turbo, the other a Pettit/Hymee/AxialFlow supercharger. All the gearing in the cars is identical because they were the same basic car prior to the installation of the kits. Even the drivers are clones.

Now, same question. Why is this so hard?

Richard Paul

iTrader: (5)

Right Ctupton, Lets for this study say we took the axial flow compressor off of a 747. Would that flow enough for a drag racer? Trouble is its efficency area is probably over 200 PSI With some ungodly 10's of thousands of CFM may be 100's I have never asked. If your really interested ask Turbine_pwr. He has the numbers in his head.

So what would happen if you ducted that air into your top fuel engine? Well if it couldn't take the air the pressure would have to rise until it did or until the compessor went into surge. Bet on the latter. So we go out and find aa small enough compressor that will flow only the amount of air that the engine cann eat at the pressure the C/section wants to give it. Plus or minus a small amount.

So what if we found a small compressor say off a buisness jet. First it would have to much pressure so we need a smaller engine to put it into. An engine that would need that pressure to ingest that mass. When we did find the combination we could beat the dragsters with about 120 cu inches. Of very stong engine.

zoom44

whats it mean when i actually understand what richard just said?^^

Ajax

I would say assume that the vehicle with the greatest area under the power curve would win. I can pretty much guarantee that that is NOT the pettit car.

rotarygod

Omicron, the answer to your question as closely as I can get it would be "it depends". If we had 2 RX-8's that weighed the exact same, were geared the exact same, had the exact same driver abilities, and the exact same powerband right up to the last horsepower, neither would be faster anywhere. However we all know that different compressors/blowers have different powerbands. I'm not even going to talk about boost pressure in psi. That is completely irrelevant. What matters most is how much power is being produced. The setup that will be fastest (this again is dependent on the scenario) is the one that makes the most power over the powerband operating area. If you have a turbo that makes the most average power within this area over any supercharger, it will be fastest. If you have a supercharger that makes the ost average power in this area over the turbo, it will be the fastest. No one here can say for sure that system "a" will be faster than system "b" just by purely looking at the spec sheet. We won't know until someone tries it. Since the Pettit supercharger is a different sized unit from Hymee's and their units are a different design altogether from Richard's, how can we directly compare them to anything else having this as our only available information? We can't. How can we compare the Greddy turbo to another turbo if we've never seen the other one on a car? We can't. Nobody here has yet seen the numbers or the powerband that 3 out of 4 of these systems will produce. There is not enough information available at this time to give you the answer that you seek. All any of us can do is to just speculate and that doesn't necessarily mean we'll be right or wrong.

Ajax

But! But! BUT!! "It depends" is such a good answer! :b

Richard Paul

iTrader: (5)

Paul, this question has no answer unless you can provide the excact power curve and gearing for both set ups. But the hint may lay in the fact that there have been very few turbo drag cars. That run with winning streaks against supers in the same class.

They were absolutly hell to drive in F1 during the turbo era. We can't assume that the Rx8 driver is in that terratory. On road courses the driver has the option of changing the ratios to suit the corner. But he can't always be right on because there are other cars on the track. Makes passing harder to plan.

Just a note as to how hard they tried to keep the compressor wheel spinning. When lifting on the throtle an iris on the other side of the wheel closes a like amount. If they both close when going into a corner the comp is closed off from atmospheric pressure thereby allowing it to keep it's speed up.

Richard Paul

iTrader: (5)

Zoom, (notice I didn't say 44) it must mean I' learning the right way to say the same thing I said before. Oh yes, not to worry to much longer because Terri is turning 45 on the 18th. She just reminded me last night. Now what could that mean?
To me it means she is getting to old for me. As you can tell she doesn't read the forum. :D


Edit) I just got it, the answer to my queston that is. Jewelry store, right. Naaa that's not it. Dumb answer.

rotarygod

Watch out with the "few turbo drag cars" comment. All of the forced inducted import drag cars are turbos. Of course none of those guys have ever played with any other setup so that may be the reason. The only supercharged import attempt at drag racing was with Adam Saruwatari's NSX when he first built it. He had picked up Jackson Racing as the biggest sponsor. They installed 2 Eaton roots style blowers on his 6 cylinder. They didn't stay there very long. That project was doomed from the start.

Rotoman

[QUOTE=Rotoman]Omicron , It seems knowone here here wants to answer your question honestly, for whatever reason, either they honestly don't know or don't want to tell you..

I'll tell you, I don't have any reasons not to tell you what my professional race car mechanics say.. I will try to explain it the the best way I can, from what they told me.

First everything being equal like you said, The Turbo would win
1. because the currently available SC does'nt flow enough cfm for the rpm range for the rx8 and even though the SC has more torque bottom end, when was the last time you raced someone and was shifting between 1500-4000rpm's...

2. They also told me that there is a formula to use for figuring out approx. power and times the car will turn..

3. I used to have a 99 corvette and a 69 Transam (rare) and I turned 11.20's and everything was set for shifting that car at 6300 rpm's in 1,2,3, gear and going through the traps at whatever was left usually 6400-6500rpm's..

4. So unless that SC is going to make power in the rpm range of the RX8 is not going to win in the quarter mile or street race... Sorry, unless Hymee or Richard Paul have a SC that will breath in that range , then we have Maybe a different store.. Don't shoot me I was just the messenger on this, But I do feel the same way..[/QUOTE]


You guys like to talk allot, around and around we go the answer to Omicron is still the same... The TURBO WILL WIN....

guy321

Oh boy! This should be good!

Richard Paul

iTrader: (5)

If it floats, flys, or fxxks, it's cheaper to rent it.

Rotarian_SC

Both SC should be able to breath in that range. You are probably familiar with roots style blowers, which won't. Your friends are probably using roots blowers, which are cheap but the least efficient. What if both SC are producing more hp from 5000-8000 rpms and the turbo only peaks over them at the top? It really does just depend.

bobclevenger

Well, I could have said "Weekly, Rivero, Fox, and Holding" but they didn't quite have the domination of their class the way SW&C did.
Yes, I am one OLD SOB.

bobclevenger

You still haven't said what kind of race it is.
And it's hard because that's just the way it is.
Why is it that if you take two "identical" cars and race them (as they do on History Channel's "Full Throttle") one of them runs faster? Because this isn't simple.

Richard Paul

iTrader: (5)

You, myself and Oldragger are the only one's here who know what you are talking about.

Rotoman

Forget it , I'am tired , big meeting in the morning and I need to prepare for, looks like I'am not going to get you guys to be realistic anyway... My point will be proving shortly anyway, good nite..

rotarygod

Please back that up with the exact scenario, and setup used on each car. Also please give us the empirical data you used to determine this result based on your own personal firsthand testing of each and every system in question. Let us know what type of track, how many different types of track were tested as well as any streets this was tested on. Let us know what shiftpoint was used on each car. How much horsepower was each car producing at comparable rpm's? What octane was being used? Who tuned it? What altitude were the tests performed at? How much did each car weight? Did driver "a" take a crap before the race but driver "b" didn't? I'm getting silly now!

I didn't go around and around with my answer. I said "it depends". Which part of that 2 word sentence is unclear? You can not just state with any degree of certainty that the "turbo will win". What if it is running at 1 psi where the supercharger is running a 12 psi and both flow rates are optimized for the application? Will the turbo still win? Excuses aren't results. Each kit will do what it does and that will be that. It is up to the end user to determine which will be best for him. Until all of the systems are available, no one can make any predictions. Personally I think the Greddy kit is wimpy but that's just me.

If your statement was intended as a joke then great and I apologize for being a hardass. If you are being serious, you've got a LONG way to go to prove your statement. There are too many variables. If you didn't test it, you guessed.

guy321

DIDN'T YOU READ THE POST!!?


His "professional race car mechanics " told him so.. so it MUST be true.

rotarygod

lol

At least I can work on my own car! I am my own mechanic.

Ajax

Maybe we're the realistic ones and you're the guy floating around on planet "turbo is always better".

Look buddy, it works like this:
Driver A and B are equal drivers.
Car 1 and 2 are equal cars except for the FI setups.
Car 1 uses turbo.
Car 2 uses super.
They are both tuned for optimal settings for the car.
They are also both tuned for optimal settings in their specific operating ranges.

Which car wins?

The car that has more area under the horsepower vs rpm curve (the integral of that curve from 0-top end if you will).

Which car will that be? IT DEPENDS!

You cannot say that turbo will always produce more power than a supercharger because it's just not true.

Thanks.. have a nice day.

swoope

iTrader: (5)

its a thread race, and this one just got a shot of nos.

beers

Ajax

hey fred, wanna come work on my car? LOL.

rotarygod

If you want to drive it down here for a weekend, I'll get you a lift in the shop.