Engine larger Throttle Body needed??

[skiwesser11]

View: https://youtu.be/0bSKy7mEsAI


‘Engine’ maybe wrong prefix but,...

Anyone watch this guy?
Pretty interesting stuff most of the time... in this video he makes the statement that the modified engine making 406 (crank)HP was being restricted by its 70mm throttle body.....I've been told/and thought I’d found through research that my FMS 65mm TB was probably best for an engine with my displacement etc.... but the engine is basically the same as video so.. does an engine with: 80mm pro m MAF, RPM 2 intake, AFR 165’s (w/58cc combustion chambers) long tube headers, H pipe no cats, 3 chamber FMaster’s with tailpipes.... I hate to spend the $ on an accufab 75mm TB and loose any throttle response and not gain any noticeable (even if only on paper) I got lots of cosmetic & suspension $’s that needs to be invested in her along with a stronger manual transmission/gear set when said $’s are available...
Thanks for any input guys!

 

[General karthief]

Don't stress over what he said about the bigger tb. The gains would be minimal and mostly in the upper rpms. For a 'streetcar' it's not worth the money.
this is, of course, my opinion, I seen many dyno runs comparing different combinations and it boils down to planning. How the car is used is the starting point.

 

[skiwesser11]

I’m pretty sure I’ve seen comparison tests that prove what you’re saying.. obviously why I’ve left it and not thought about anymore... thanks!

 

[2000xp8]

Let's not forget that an rpmII only has a 70mm opening.
I'd just leave it.
In street cars it's no longer a game of a couple horsepower like it was 25 years ago.
When everyone was low mid 12's? Sure a few extra helped, but now people are taking Shelby's, zl1's, hellcats to 700rwhp with SC pulley's and tune's and running 9 second timeslips.
Not sure 5rwhp is going to help anything other than making you feel a little bit better about not leaving any power on the table.

 

[96pushrod]

Let's not forget that an rpmII only has a 70mm opening.
I'd just leave it.
In street cars it's no longer a game of a couple horsepower like it was 25 years ago.
When everyone was low mid 12's? Sure a few extra helped, but now people are taking Shelby's, zl1's, hellcats to 700rwhp with SC pulley's and tune's and running 9 second timeslips.
Not sure 5rwhp is going to help anything other than making you feel a little bit better about not leaving any power on the table.

Important to remember that. If you’ve got a bigger inlet on your intake, by all means run a bigger throttle body. You can only move as much air as you’re smallest opening, of which you have both which are the same size.

 

[skiwesser11]

Let's not forget that an rpmII only has a 70mm opening.
I'd just leave it.
In street cars it's no longer a game of a couple horsepower like it was 25 years ago.
When everyone was low mid 12's? Sure a few extra helped, but now people are taking Shelby's, zl1's, hellcats to 700rwhp with SC pulley's and tune's and running 9 second timeslips.
Not sure 5rwhp is going to help anything other than making you feel a little bit better about not leaving any power on the table.

Agreed, he was talking like it was really holding it back with a 70mm@ 406hp... I’m currently using a FMS 65mm throttle body and dyno tuned to 341 after being heat soaked for 45 minutes between idling and 4 pulls between 1st & last...1st being a 336hp base run, the AL9 was doing ok!
Anyway I figured if it cooled down some it’d have made 350ish which should be just over 400 through a 5 speed drivetrain.. but again? I think I agree with what you’re saying... I want boost but with current cam was advised by Flowtech to not give it more than 10# so... that just won’t satisfy lol... so boost is for the next engine I suppose

thanks again guys!!

 

[skiwesser11]

Important to remember that. If you’ve got a bigger inlet on your intake, by all means run a bigger throttle body. You can only move as much air as you’re smallest opening, of which you have both which are the same size.

this is what made me begin to wonder, but like General said, I’ve seen several comparisons that show nearly no to slim gains above 65mm on the same general power level...Accufab is about all I’d consider and they’re not cheap... too much for only 15 or less crank HP IMO. And there’s velocity to consider too I suppose as I’ve seen a giant TB (90mm) loose a good bit of power on a mild engine in some test(s)

 

[JD1964]

A 65mm TB has at least 660cfm capability. That can take a 306 beyond 7000 rpm no problem. Is your engine gonna see 7000rpm? I doubt it. 65mm is plenty.