Today I went out and did a few runs logging some data so I can get timing dialed in before I hit the dyno in a couple weeks. What I noticed is that I was pulling up to 2" Hg vacuum at 5600-6000 rpm. My setup conisists of XE224/230 110 lsa, LE ported heads, FIPK and stock 48mm TB. Apparently 48mm tb flows enough air to support 450rwhp and Im definitely not making that kind of power but looking at the data I have to ask myself if a larger TB is needed. What do you guys think? Below is my log. WOT run is right at the end.

http://www-personal.ksu.edu/~bperkins/wot.uni

.uni file doesnt seem to be working right... try this .zip file with .csv and .uni

http://www-personal.ksu.edu/~bperkins/wot.zip

 

I'd say quite possibly you do. Throw a 52mm on there and run it again.

I've got a Holley 52mm for sale if you're interested.

 

My car did the same thing (just a little more vacume). I had the intake ported and changed the TB to a AS&M 58 MM, problem solved.

 

2" Hg is a restriction. Work on eliminating restriction to 1" Hg or less.

-Mindgame

 

Saved the zip file and tried to open it, but it just kept flashing the pop-up that asks if you really want to open the file.

I checked one of my data logs... at 7,114rpm in 1st gear (52mph) the MAP was down 3.8kPa (1.12"Hg) from the barometric reading. 381 ci, WS6 style Ram Air intake box with K&N, no MAF, smooth connector, 58mm Holley. At 6,783rpm in 2nd gear is was only down 1.8kPa (0.54"Hg), but at that speed (83mph), there should be some small pressure gain from the air intake.

 

Thats odd. I tested the link and it works fine for me. Not a whole lot to see anyway... just some numbers to justify what I was saying. Do you guys think this is TB related? I may do a run later today bypassing the FIPK so maybe that will help out. Arent we talking at least 15 rwhp gain if I can keep it under 1" Hg?

 

I checked some of my logs before my 58mm throttle body, when It was stock
My KPA was over 5 down from the outside air....Dont have the calculation chart, But its near 1.5", This was pretty consistent with 1st and second gear near 6000 RPM's.
Now, wiht my 58mm throttle body, I will see within .5 KPA in 1st and 2nd gear, and sometime positive vacum during the higher gears, This is with an LS1 lid setup on an LT1 that has a Fast toys ram air setup.

This is a stock bottom end car with an LE2 heads and cam, stock intake.

Looking at vacum, would be the way to tell if it does need to upgrade the Throttle Body,m as far as 15 RWHP, You would have to be down on the KPA from the map reading quite a bit to see loss that much HP.I cant look at the logs files right now, So I would need to get back to ya on that one.

Hope this helps some

Joseph