70mm throttle body question

[2oo3MustangGT]

so i have a completely stock engine other than a cold air intake and now a 70mm throttle body. i havn't put it on yet but i was wondering if i needed to port out the stock plenum because of the bigger TB. i doubt most people do it and if it's not necessary i won't either, but if it's not going to be any better than the stock (60 or 65?? mm) TB then i will port it to get the benefit of a bigger TB. it's a ford racing TB and it's going on the stock plenum...any suggestions?

 

[Winters98GT]

you will not gain anything with the tb alone. We did a dyno of the FRPP TB on my 1998 GT with PI heads at 264rwhp, we gained nothing, so I went back to the stock one. This was back in 2001, so the plenums were not part of the equation then.

 

[BrothersPerformance]

I wouldn't say you're not going to gain anything with the TB alone. It just won't be much, and it may not be in the RPM range where you normally drive day-to-day. You may see a gain of 4-8HP but it may be in the upper range of like 5,000RPM or higher.

I DO agree that porting the plenum isn't going to make a difference either.

You'd probably see some good change with a custom tune after the throttle body install, and that's what we'd recommend. If you have the car dyno'd after the install, be sure they test it at the higher RPMs (if you're comfortable with that).

With this model though, you'll probably get the highest HP gains with a Cold Air Intake (which you have) and working on freeing up that restricted factory exhaust flow (if you haven't started on that already). I just checked with our tech/sales guy and he agrees.

 

[2oo3MustangGT]

thanks for the help, that's kind of what i was thinking too, but always nice to hear what others have to say. i definately do want to get a dyno tune soon so maybe that'llbe the next mod investment

 

[Winters98GT]

You don't need a dyno tune. Leave the stock tune until you upgrade the heads/cams, or add gears.

 

[2oo3MustangGT]

also good to hear. i had a buddy of mine get an extra 30ish rwhp from a tune but his was supercharged. i doubt i would pick up too much hp from mine with only intake, tb, and catback exhaust it's pretty stock so it might be a waist of money.

 

[Winters98GT]

Most likely, the HP/tq increase will be from the increase in timing.