Gretch

you mean like:

hacker-pschorr

That's it, this thread is officially OT and going down the crapper.

SteveM928

The key word there, and what was being talked about, is POWER. Seems to me that's measured on a dyno. As for peak numbers, area under the curve, etc., the dyno charts that have been posted in the past make it very clear who's making the most peak power, most bottom end power, and also has the most area under the curve. Hint: they're all the same setup. Until some new dyno charts get posted showing something different, there's not much point in speculating on it.

If we're going to go by just the posted 1/4 mile times, even though very few have been posted, the winner would be Devek's stroker motor. A while back Marc Thomas posted that he ran 11.28 @ 128mph on street tires.

Until some more cars actually get out on the drag strip, how can anyone claim superiority if there's nobody to compare to? Marc can say his car is fastest top speed wise because none of the other fuys have done that. Andy can say that his is the fastest supercharged car in the quarter mile because none of the other supercharged cars have done that that I've heard of here. The only way to make any sort of meaningful comparison is to use dyno charts, since they show power only and that's what's being discussed here, and because all of the cars being compared have done dyno runs. Seems simple enough to me.

bcdavis

There was a funny thread on another board, where a group of guys went about disproving all the stuff about big wings, motor mods, etc, as the source of good quarter mile times. Their goal was to make a 10 second car out of a stock honda civic or some such economy car. So they just kept removing weight, and removing weight, until they actually removed the roof, the hood, the doors, the trunk, and eventually ran a 10 second time, with the stock engine. It was pretty much just the floorpan and drivetrain when they were done. I can't find the link right now, but the photos were hillarious.

mspiegle

I agree. Someone should lock this thread, it isn't even about superchargers anymore.

shaaark89

andy,
i can give you some lap times if you'd like.
summit point 2 weeks ago. vir next week. totally custom setup.
vortech with 7-8 lbs boost nonintercooled (for now), 100 octane race gas, electromotive igition control.

GoRideSno

Thanks Tom,
I am sure your times are extreeeemely fast.
What I am really interested in is how fast other street 928s that aren't gutted, w/ race tires, bored and stroked, etc are. I want to hear from the guys that have just bolted a system onto a stock 928 w/ out a lot of other mods, preferably not chips exhaust etc. I have just never seen any street performance meteric stated form any of them.

SteveM928,
I guess I should be more specific and say before and after 0-60, 1/4th mi etc. The meteric or measure would be before time against after time. But I am still surprised to not have seen any times. After all Porsche puts not only HP figures but 1/4 m time and 0-60 in the owners manual.
The stroker car car time you mentioned is extremely quick. Dosen't surprise me in the least. Was it the White car? How much does the car weigh w/ driver? Mid 2klbs range seems familiar. What's funny to me is that when I posted my 1/4 times a while ago Marc was on the thread and mentioned that he went to the 1/4 track and Susan said "no more" when he smoked the clutch a few times IIRC. No mention of his exceedingly fast time. Humble guy I guess.

Andy K

BTW looks like Chris has made his decision.

shaaark89

that was a tongue in cheek response, sorry should have put some smileys there

Lagavulin

This is a rather disappointing development.

As several have already noted, SAE dyno charts are the most pure of automotive metrics available in the world; it's just the car and the dyno, no other variables involved. An SAE dyno chart from the Middle East can accurately be compared to an SAE dyno chart from the East Coast.

Since you brought it up...

With all else being equal, it is generally accepted that each 10 horsepower gain is worth 1/10th of a second in the quarter mile; and each 100 lbs lost is worth 1/10th of a second. And each 1/10th of a second can also be viewed as one car-length in the 1/4 mile.

According to same-psi dyno charts, the Whipple shows no low-end advantage over the centrifugal, and it also shows the Whipple having a 90 horsepower deficit on top.

Using your corrected 1/4 mile time, what would be your new time if you had an extra 90 ponies on top where hook-up is good? That would take you from 12.4s down to 11.5s, a HUGE difference, and 9 car-lengths at the track.

It seems strange to me that you would attempt this argument in the first place knowing what the numbers are and what they imply.

At least he made an informed decision, and I'm sure he'll be happy with his choice since you have a good kit. However, evidently he based his decision upon considerations other than horsepower.

It's all in the dyno charts to see.

Tony

Lags, i dont think Andy means to stir the pot with this AT ALL. What he says about a lack of "performance figures" is true. We have all seen dyno charts for various set ups now. Stroked, Vortech'd and Twin Screw etc. Yes, DYNO CHARTS are a bench mark for performance and there are many charts out there to view and for people to make judgement, but the other part of the equation i think is how these charts relate to performance on the "street" . ie 0-60 1/4mi 60-100 etc etc. Im sure your car absolutely hauls A$$ as does the white car, but to put it in perspective for many folks including my self, a "street"performance figure is handy. I cant link the previous post on the computer in the lounge right now but i posted somewhere how Andys car compared to a new GT3 on the drag strip after he had posted his times slips. The GT3 times were from a article in the last Excellence. It was pretty neat to see how our "old" cars rank now with a bit more ooomph behind them.

You could post a dyno chart of a GT3 and your car side by side but it wouldn't mean any thing to me performance wise.(dont take that the wrong way..dyno chart are VERY important) Yeah you make "X" power here.."Y" torque there...this much area etc etc, but having some "street numbers" to see how the power is utilized on the road is a great tool.

Good for some bragging rights as well.

GoRideSno

Lag,
Please provide the same "psi dyno charts". Also when you provide those charts make sure the cars are the same model and year have same transmission same tires and wheel size and model. Please make sure each of the cars has a no other modifications that what was necessary to install.
I think we have been through this already?

Just put your money where your mouth is and get some sort of time and post it. Arguing over the internet is a bad thing and brings us all down. Going out and geting new fast times is a good thing and brings us all up.




Andy K

SteveM928

I don't know why you're surprised. It hasn't been long ago at all since you said that you had never been to the drag strip, and had never even dynoed a car before. There aren't that many supercharged cars out there yet, and those that are haven't been around long yet. How long have there been stroker motor cars out there, and besides Marc Thomas I've never seen even one post 1/4 mile or 0-60 times. Those types of times are very rarely posted even for normally aspirated and stock displacement 928s, and there are thousands of those that have been out there for decades. The tracks aren't even open yet for the season in most of the country. I'm guessing as more and more cars get supercharged and as the racing season gets underway you'll start to see some of those times start to appear.

Yes, that time was from the white car. At the time the weight was probably closer to the mid 3Klbs range though. That was a while back, when the car was used primarily for open road racing and hadn't had the weight reduction that it's gotten since getting more involved with the track stuff. Can't say for sure if Marc had posted that here on the discussion board or not, but he did post it in several other places, including the Rennlist and PacNW mailing lists. Below is his post to the PacNW list that can be found by doing a search there:
-----------------------------
From: "Marc Thomas" <mmthomas@i...>
Date: Tue Sep 9, 2003 11:09 am
Subject: Re: Fastest Quarter Mile in a 928

11.28
128mph
street tires
456 rwhp
pump gas

one bad smelling 928 post run
lucky to drive it home.....
--------------------------------

I'm kind of surprised that you brought up the question of weight for that car in regards to the 1/4 mile time mentioned. It's exactly one reason that a 1/4 mile time is not a particularly good indicator to use for comparisons of power adding methods. The fact that so few others have done that sort of measurement makes it even less of a basis for a good comparison at this point.

Yes Lag, and make sure it's the same color and that the same radio station is playing as well.

Why do you want so many more things the same for the dyno charts, and yet not seem to have any problem with drag strip times that have an absolutely huge number of greater variables?

As long as we're on the subject of 1/4 mile times, don't put too much faith in those "corrected" drag strip times. While the correction used is better than nothing, there are an awful lot of things that it ignores. It adjusts for power differences based on altitude. You'll make more power at lower altitude, but you aren't going to necessarily have the traction to use that additional power, especially on street tires. Want good corrected 1/4 mile times? Go to the highest elevation track you can find on a cold high atmoshperic pressure day, and then "correct" that time to sea level. The times will look impressive but definitely won't tell the whole story.

John..

You guys can argue dyno pulls all you want, remember there are lots of correction factors entered into the machine. It is all crap until you put the rubber to the road with some real performence specs. The positive displacement blower is so far superior to ANY centrifugal setup out there that it is not even worth the comparison. Go ahead, ask the experts on this subject and see what you get for an answer. There is a clear reason there are no factory built cars with a centrifugal supercharger, it is simply inferior to the other forms of forced induction out there.

Let's say you come off of a corner at 3000 rpm and hit the hammer, the positive displacement is already making boost while the CS has to wait to 2/3 redline to make any significant boost. That is a fact with or without dyno numbers to back it all up. How about rolling on the throttle at highway speeds, say 3500 RPM in 5th? Again, positive displacement has the boost now, with the CS you won't even have 3 lbs at that RPM, so you have to downshift, you lose at least 1/2 a second while Andy is already gone.

The dyno comparision is not at all fair, it does not clearly identify the transient response of the vehicle on the road, nor does it load the car like the road will.

We all play the dyno game, but I (among others) are still waiting for these Super Shark performance numbers. It is cheaper than two runs on the dyno, so do us all a favor and buy the G-Tech and post some straight line numbers....as much as I hate drag racing I would be interested if the performance would be better than Andy's car. I suspect it is not and my wager is that side by side in the real world Andy's car would have the clear advantage in all around street performance.

GoRideSno

Lag,




There are no same psi dyno charts.




If there are please provide them.


Maybe they are in the same spot as the extra HP is from when you calculated John's HP on his TT car.




TIA for providing the same psi dyno charts
Andy K






I am glad to see that Marc's time is extremely fast. A time like that is a great contribution to the 928. If he posted that time slip instead of a dyno chart he would probably sell a lot more stroker motors and parts than by posting a dyno chart.

Tony

Steve! Thanks for posting the 1/4 mi numbers of the WhiteCar, i had never seen those before! Very cool and VERY FAST!

DISCLAIMER: YES, DYNO CHARTS are very important...but

I dont know about you guys, but when i browse though MotorTrend, Car and Driver..Excellence etc etc. I always take a look at the performance stats for the cars. Hp..TQ..0-60...1/4mi etc . When i do, i often find myself weighing up the "competition" out there thinking to myself, Yup, i could hang with that car ...that one..or that one. Sadly, with some of the cars out there today coming of the show room floors, our 928 is a pig! Yes i said that. Truth hurts doesnt it!

The bottom line is, Im glad we are getting more and more options availbale to change that with the work that Tim, Andy, John and Marc are doing..and others in the shadows