And what else did you change to get the rest of the horsepower responsible for that increase in trap speed?

Let's say you've got a 3,000 lb. car with a manual transmission (~15% drivetrain losses). With a trap speed of 102 mph, that's equivalent to about 255 horsepower at the flywheel. Sound familiar? To increase trap speed to 107-108 mph, though, you'd need 294-302 horsepower at the flywheel, or another 39-47 horsepower. In other words, you couldn't pick up 5-6 mph in trap speed on even a stock FD just by "ramming" air into the air box.

Let's take the same car and calculate the horsepower required for a 117 mph trap speed. Oddly enough, it works out to just about 325 at the rear wheels, or ~384 at the flywheel, which corresponds very closely to the dyno results and trap speed of my friend's R2. What would it take to increase trap speed by 5-6 mph? 435-445 horsepower at the flywheel. Once again, you're not going to manage that with just a "ram air" intake.

 

these aren't the greatest scans. but i found it interesting.

http://www.geocities.com/s0ulrane/pics/rx7scan3.jpg
http://www.geocities.com/s0ulrane/pics/rx7scan4.jpg

 

Both links bring up a "page not available" error at GeoCities.

 

sorry about that. this should work now.

http://www.geocities.com/s0ulrane/page.html

 

TURBO INLET PRESSURE EFFECT

increasing inlet pressure, for a fixed boost, will reduce the pressure ratio, make the turbo work less at lower rpm with less pumping losses, reduce manifold temps, and reduce exh dilution of the intake charge.

this is not a big effect.

this link is to an excel spreddsheet that i've checked and corrected. this shows the effect of pressure drop in the intake on the charge temp and the mass flow rate. it does not account for slight changes in the compressor efficiency. it does not consider exhaust effects.

just vary the the intake pressure drop in the far right rpm column, and see effects on intake temp and the TMf, or theoretical mass flow. drop of zero means atmospheric, and -.5 means a ram effect pressure of .5 psi 'boost' at the turbo inlet.

fyi, in the prior posted motorcycle link, 30 mbar is .44 psi.

http://johnbaas.dyndns.org/audi/VE.xls

 

Jim,

I didn't make any changes when I did the tests. I dont have my data with me at the moment but the first comparisions were with stock air box, highflow cat, catback, power FC, small SMIC only. First runs were done with stock air box with K & N filter. The next set of runs were identical with a ram air going into the bottom of that box. The gain was 3-4 MPH on the trap consistent.

The 2nd set of tests over the next few months were done with an rx-7 fasion air box and midpipe, everything else the same as above. The initial test over the first month or so had no ram air. My trap actually dropped over what my trap was with the highflow cat and ram air in the stock air box.

The next set of tests were done with the same setup but a ram air into the bottom of the rx7fasion cold air box, this was done over a month or 2. The result was 4-5 MPH average over the same setup without the ram air.

 

But that is not a true ram-air system, only a "cold air" intake. In order for ram-air to work on carburetors, you need to pressurize the float bowl, and IIRC, NASCAR rules prohibit any modifications in that area. Plus, due to the constant drafting that occurs in stock car racing, any type of ram-air pressurization would be upset by the turbulence and cause a loss of power.

Which is why I mentioned the "wacky duct protruding out into the airflow". I guess "wacky" may be a rather harsh adjective (seeing as how F1 cars use a vertical intake positioned above the driver's cockpit), but I was envisioning the same sort of duct protruding out of an FD hood. Yes, you can get high pressure zones anywhere you want, but in order to realize the maximum benefits of ram-air, you need a clean, uninterrupted flow of air (and at least some intake/airbox design) to prevent a lot of the niggling problems that occur from using airflow to pressurize the intake area. And...

Which is why I mentioned positioning the intake duct on the front of the car, because you have a clean, uninterrupted flow of air at fairly high pressure due to the frontal area of the car. It's the easiest spot to source high pressure air without going through all sorts of fabrication to build what would probably turn out to be somewhat of a wart on the FD's clean body lines.

 

In other words, track and weather conditions certainly varied and there was no data collected about engine coolant or oil temperature during runs, so there was no baseline and basically it's all worthless data.

Facts are facts... you can't pick up 5-6 mph (or even 3-4) in trap speed in back to back testing with only the addition of a hose to the air box from the front of the car.

 

I thinks ZB's tests are very helpfull. It shows that bringing additional air into the airbox increases your trap time in the 1/4 mile. An obvious HP gain. How much, I cannot say.

The RX7 Fashion airbox is less restritive than stock. This test proves that the engine can and will accept more air than the aftermarket box will allow, without additional pressure feeding the box.

ZB's test cannot not be discounted as irrelevant.

 

I REALLY hope we don't get another WWIII goin between Zerobanger & Jimlab lol

 

Thanks for the support, JimLab just likes to argue.

 

I think adam's last line "cannot not be" was a mistake. I think he was supporting you.

Unfortunately, without evidence of apples to apples tests, your claimed results will be subject to criticism and/or doubt.

 

I meant to quote jim lab, oops.

 

Like I said, I took averages over many months of testing. You can relate it to what ever you want but when I have the ram air I consistently had the higher trap speed than when I didn't. Your opinion is just an opinion. My tests were done well and any reasonable person would understand it.

 

That was a typo. The extra "not" shouldn't be there.

I meant that the tests are valid.

 

The stock box inlet elbo is very restrictive. I measured about 1.2 psi of vacuum at 6K+ in the box on a stock FD, with no filter in place. This may have been the biggest factor in your stock box testing.

 

Any intelligent person would understand that the difference in track conditions, temperature, humidity, tire condition, the heat of your engine, or the amount of gas in your tank could skew the results... I guess you're not one of them.

Your "tests" mean jack ****. Go back to posting in the lounge.

 

any thread that you are involved in is the lounge. My tests are valid, Im certain of it.

 

Another autospeed article on where to mount your intake.
http://www.autospeed.com/cms/A_1023/article.html

Unfortunately, this one requires a subscription.

 

1.2 psi of vacuum? Vacuum is measured in inches of mercury (in. Hg).

I'm still waiting for someone to mount a boost sensor on their bumper or hood and show me they can achieve 1 psi to add on to the 10 psi their turbos are producing...

 

A valid back-to-back test starts by establishing a baseline, making a change, then equalizing engine temperature to the baseline, and then making a comparison run on the same day under identical conditions, or as identical as possible.

What part of your "tests" do you believe resembles what I've just described? That you went to the same track?

 

Statical data is more accurate when a large sample is taken. If ZB was trying to prove his point with only a few samples, you would be correct in questioning him. However, he has a large number of tests which strongly support his conclusion.

 

If Jim Lab is so damn sure of himself he can hand pick someone in northern cali to meet me at the track. I will take 2 towels and stuff the hoses under my car for 2 runs and remove them for the other two.

I will run my water injection so heatsoak will not be an issue.

im very confident of my findings. Put up or shut up Jimlab.

 

If his data were collected in controlled conditions, it would support his conclusion. Since it was taken with no baseline, no way of determining if additional weight from fuel or or track conditions affected the outcome, it's useless.

 

I always run my car with only a gallon or 2 in the tank. I weight it at the track most of the time. There was no extra weight.