Atco Dragway 12/14/08

[TomsSVX]

Originally Posted by Phast SVX

overboost is a typical symptom of an undersized impeller... like you said keep the boost down and tune the **** out of it. again congrats

Didn't even think about that... I already knew the charge was getting too hot... Might be time for some Methanol injection pre-blower

Tom

[Tim]

I can only imagine the power you are putting down.

My friend's 400hp 6.0 liter GTO weighed in around 3800 pounds and ran a 13.33 at 106.

You must be pushing 350 hp or more

[Mike621]

Because I'm still waiting...

[SVXRide]

I'd have thought the rear tires would look "flatter" with only 20psi in them
-Bill

[TomsSVX]

Originally Posted by SVXRide

I'd have thought the rear tires would look "flatter" with only 20psi in them
-Bill

Not with those stiff sidewalls... Those tires are not exactly "drag racing" appropriate

Tom

[Mike621]

http://www.youtube.com/watch?v=wMeDMPCpoD0

Here it is.

[TomsSVX]

Originally Posted by Mike621

http://www.youtube.com/watch?v=wMeDMPCpoD0

Here it is.

nm its worky

tom

[TomsSVX]

lol@ eric...

Tom

[Mike621]

Originally Posted by TomsSVX

lol@ eric...

Tom

That was my first thought, well, right after "holy **** that was quick!"

[SVXRide]

How about that, no flames coming out of the tailpipes!

-Bill

[immortal_suby]

that ****ing rules! congratulations on getting into the 12's

[TomsSVX]

Originally Posted by immortal_suby

that ****ing rules! congratulations on getting into the 12's

Thanks but it is only by the skin of my teeth

I hope to have it consistently running 12.5-12.7 w/ a good tune on it next spring, its getting time to put it away for the winter.

Tom

[Sov13t]

Was a lot of fun to drag for the first time.

Granted my results are at best sub-par, I was happy with the improvements and lessons that I learned during the 3 runs that we had.

I kept trying to concentrate on specific aspects... like for example paying attention to how I launch... and then I would be like ... "oh... @&^!# SHIFT SHIFT SHIFT!" then another run I would try to pay attention to shifting... and so on...

Run #1
Hydra EMS, spun tires at launch for a bit...

R/T  ...   .276
60'  ...  3.077
330  ...  7.677
1/8  ... 11.522
MPH  ... 66.45
1000 ... 14.731
1/4  ... 17.362
MPH  ... 86.75

Run #2
Hydra EMS, 3000 RPM launch

R/T  ...   .177
60'  ...  2.326
330  ...  6.559
1/8  ... 10.013
MPH  ... 69.69
1000 ... 12.984
1/4  ... 15.500
MPH  ... 88.52

Run #3
Stock ECU, 3000 RPM launch

R/T  ...   .215
60'  ...  2.383
330  ...  7.028
1/8  ... 10.756
MPH  ... 65.92
1000 ... 13.924
1/4  ... 16.652
MPH  ... 83.04

Until next time
Perhaps in a totally different car?

Thanks Tom, Mike and Eric for having me over yet another time
-Sov13t.

[shotgunslade]

Congratulations, Tom.

The issue with the pressure rising at high rpms is not surprising, but it isn't that important unless your intake manifold leaks. Your Whipple is what is called a positive displacement device, in that it grabs a fixed volume of intake air and compresses it to a much smaller fixed volume. The total volume of air it moves is linear with rotational speed, no matter what the exit pressure.

This is in contrast to a centrifugal compressor, as used for turbochargers, which develop pressure and thus ability to create flow with the square of the rotational speed. However, the airflow downstream of your supercharger may become very turbulent at high rpms, creating significant pressure drop. Unless your intake manifold is leaking, that amount of air that is getting into the engine at a specific rpm is fixed, it just may take more pressure to force it through the intake pathway. The only downside of this pressure drop is that it takes more power to drive the blower.

That is why intercoolers aren't nearly so advantageous for a positive displacement device as they are for a centrifugal device, such as OT's supercharger. Because flow through a centrifugal compressor is dependent on exit pressure, cooling the air heated by compression in the supercharger will reduce the exit pressure thus increasing flow. With the Whipple, the exit pressure has no effect on flow, just on compressor drive power.

On the other hand, pressure drop on the intake side of the compressor at high rpms is very important, because air density will be reduced by inlet pressure drop. So, your fixed volume of air that the compressor is moving at any specific rpm will have less mass if there is high intake pressure drop on the intake than if there is low intake pressure drop.

So, bang for the buck with a positive displacement compressor is to reduce pressure drop on the intake side of the compressor. The pressure drop between the compressor and the cylinder will have little impact on engine power output, except tthrough the parasitic power to drive the compressor.

There will be a pop quiz. Tom has already been given a bye on the exam and has an A+ for the course. The rest of you, study up.

[sicksubie]

I cannot wait to get my car straightened out and this installed. If Tom is running 12.99 on a base tune on a stock block, what will I be at with a built motor, the bigger pulley, methanol injection, and twin intakes