New Heads/Cam or Nitrous???

[tmoss]

with intakes the smaller cross section in the runners, TB size has more to do with throttle repsonse than anything else. the difference in flow area opened with every degree movement of the throttle blade is VERY different between a 60mm and a 80-90mm TB. It ain't rocket science. Can a TB be too small? - yes. Can one be too big? - for total flow, no, but it can also result in unacceptable part throttle response depending on the needs of the combo.

An all or nothing stance on the issue shows lack of understanding.

 

[95strokerPSU]

but it can also result in unacceptable part throttle response depending on the needs of the combo./QUOTE]


What affect do you think it will have on my combo?

 

[WhiteDevil]

I have the same heads as you and we did talk a little back and forth with PM's. Ed said that the heads were not too small but just a little smaller than he would reccomend for a stroker but it would not stop me from being in the 340rwhp range which is around what i was looking for. I havent gotten on the dyno yet but going by TwEECer data logs i have peak air flow around 5,800rpm. 75mm tbody, 75mm elbow, and i opened up my edel rpm inlet to 75mm as well.

 

[tmoss]

but it can also result in unacceptable part throttle response depending on the needs of the combo.

What affect do you think it will have on my combo?

I'll ask a couple of questions and see where you think you should be......

Your MAF is a 75mm - how much of that area is taken up by the sensor restriction?
if the area is less than 75mm of free clear & clear flow area, how is a 75mm TB gonna help?

always look at the most restrictive part in the flow path first.

throttle reponse depends on many things besides TB balde size, but the 70mm may have better off-idle driveability than a 75mm - as long as the MAF is not the biggest restriction. How are you going to drive the car? - on the street most of the time or at WOT at the track most of the time? Everything is a compromise in trying to hit middle ground.

 

[95strokerPSU]

Well I'll be going with the 90mm Lightning meter so that won't be the restriction.

The car is mostly a street driven car but by no means a daily driver.

 

[tmoss]

then the 75mm ought to work for you........now go get a good one.

 

[95strokerPSU]

Thanks again everyone. I have most of my parts ordered and I'll hopefully be sending my intake to Tom on the 18th. Here's what I got....

Walbro 255lph HP
30# FMS Flow Matched Injectors
Lightning 90mm MAF
4" Aluminum Tubing (that I'll either polish, chrome, or Jet-Hot coat)
Accufab 75mm Fox TB
3/8" Billet EGR Spacer

And I think I'll be adding a 100 shot before I have it retuned at JDs.

 

[BlackVert]

Thanks again everyone. I have most of my parts ordered and I'll hopefully be sending my intake to Tom on the 18th. Here's what I got....

Walbro 255lph HP
30# FMS Flow Matched Injectors
Lightning 90mm MAF
4" Aluminum Tubing (that I'll either polish, chrome, or Jet-Hot coat)
Accufab 75mm Fox TB
3/8" Billet EGR Spacer

And I think I'll be adding a 100 shot before I have it retuned at JDs.

man ... matched injectors are very expensive.

jet-hot is the $hit

75 mm = 7.5 cm
7.5 cm * (1 in / 2.54 cm) = 2.95 inches at the throttle body

why have a 4" pipe going to a 3" opening?

seems to me you should really be at 3" for at least a foot before the throttle body, otherwise you will have turbulence going from 4" to 3" at the tb, which is bad.

on mine, i'll be going 4" from filter to the LMAF, then step down to 3" from the LMAF to the TB.

 

[95strokerPSU]

man ... matched injectors are very expensive.

jet-hot is the $hit

on mine, i'll be going 4" from filter to the LMAF, then step down to 3" from the LMAF to the TB.

I actually got the injectors used (20 minutes of dyno time) for $200 shipped. Otherwise I would have gotten regular ones.


Maybe I'll do the same as you for the tubing, do the 4" to 3" drop down after the meter. That will actually be cheaper.