wadzii

In all my years of running dyno's/tuning cars I have NEVER had a car loose power by making the intake longer

IMHO, the stock s2000 intake manifold is so crappy that all the harmonics are basically killed off in the crappiness.

Im on vacation this week, so it will probably be monday before i get any logs posted. and when i hit the dyno next week i'll swap out all the different intakes i can find.

wadzii

I just did a quick data log since the new 4 inch intake, It made no difference in the MAP readings, I still have almost 1psi of vacuum past 8000 rpms.

Anyone have a set of cams I can borrow to test.

Dyno appt is this afternoon

Gernby

I'm not sure how 1 PSI of vacuum would convert to mBar, but it sounds like a lot. Here are 2 datalogs I did on Sunday using my PWJDM intake (Red line) and my OEM air box that I gutted and insulated. As you can see, the MAP curve is almost identical with an offset in favor of the PWJDM by only about 5 mBar on average. BTW, this is an F22C with stock internals and decent bolt-ons.

wadzii

just hit up google for the conversion...

1 pound per square inch = 68.9475729 millibars

atmospheric pressure = 1013mbar = 0 psi

I ran my log from 3000 rpm up and the line is very similar to yours

it starts at about -0.1 psi/1000mbar and declines to -0.95psi/948mbar at 9200 rpms

I cant find the logs from my stock motor but if i remember right there was only ~0.4psi of vacuum at 9200 rpms. I know it was significantly less that what i'm seeing now.

A GOOD intake setup should be close to 0 through the whole range.

Gernby

I think you are misunderstanding what the MAP is measuring, and possibly how atmospheric pressure works. Atmospheric pressure changes constantly throughout the day based on weather patterns (barometric pressure) and altitude. At my current altitude (~ 600 ft), my MAP reads at most 990 mBar with the engine turned off when barometric pressure is really high. On a typical day, it would read about 970 mBar. If I went to Colorado, I believe peak mBar would be in the 800's or less.

wadzii

I understand how it works.... I was assuming your key-on-engine-off map reading was similar to mine. Mine is usually within a few hundredths of 0psi. I think it was -0.06 this morning.

Since your key on-engine off reading is that lower then i'd say your' in a better position than I am as far as everything working together.

bottom line is that at WOT, manifold pressure should equal atmospheric pressure, the line should be flat, it should not decrease with RPMs.

Gernby

So let me get this straight. Are you sayind that the atmospheric pressure in your location at the time you did the datalog was 1013 mBar, and that your MAP was reading 1013 mBar before starting the car? If so, then I retract my post above ...

Gernby

Just saw this post...

Which throttle body are you using? I just can't see how your engine would be pulling so much more air that it would pull that much more vacuum than mine.

wadzii

pretty close.. i look at my units in psig

my intake manifold and throttle body are stock ap1 stuff.

its probably a combo of the longer rod, valve job and ap1 cams (I assume you are using ap2 cams?)

Gernby

It seems to me that your throttle body might be a bottle neck. Honda increased the diameter of the TB in '06 to be about the same size as the SOS Big Bore TB.