[prxr88]

Unless you go with a custom larger diameter intake you aren't getting any more air than usual. You can get the largest TB you want but if you stick with an off the shelf intake you are getting the same volume of air. And even if you do get a custom intake and bigger TB the intake manifold can only hold so much air and the intake valves will only let so much air into the combustion chamber

a bigger intake is common sense.

if he bores the IM to 70mm with the corresponding TB it is definatly more efficient.

i wasn't argueing about the 74mm. if you were wondering

 

[Iheart7dc5]

this is really good info

Seeeee I'm not afraid to ask stupid question :bow:

 

[cencalep3]

 

[K20R-Kat]

this was much needed info for me :beerchug:

 

[Jordan Dc5]

If your trying to break records, make over 300 hp all motor upgrade your throttle body and bore the manifold accordingly. But in my opinion its not worth the 500 dollars + for maybe 5 or more hp and some torque.

 

[Ukinayo_DC5]

If your trying to break records, make over 300 hp all motor upgrade your throttle body and bore the manifold accordingly. But in my opinion its not worth the 500 dollars + for maybe 5 or more hp and some torque.

OP stated he is buying cams for his setup, whats the point buying cams if he is restricting the amount of air going to the engine on a mild NA cams setup, plus the only thing that would cost more than $200 would be an aftermarket throttle body, you can port the manifold to 70mm yourself for only 14 dollars just by buying and using sanding drum or even taking it to a local machine shop which is still cheap.

 

[xxyauxxdc5]

OP stated he is buying cams for his setup, whats the point buying cams if he is restricting the amount of air going to the engine on a mild NA cams setup, plus the only thing that would cost more than $200 would be an aftermarket throttle body, you can port the manifold to 70mm yourself for only 14 dollars just by buying and using sanding drum or even taking it to a local machine shop which is still cheap.

bump from the grave! i recently found a fully ported rbc with ported 74mm tb for 500. do u guys think its worth it? i already have a stock rbc with a 70mm opening to a skunk2 70 mm tb.

 

[alexEF]

that's a good deal for 500.

 

[tkane4389]

Spend your money on something worthwhile. If you're doing cams, pull your head and take to a machine shop. Get The head redecked, valve job and ATLEAST bowls blended and intake gasket matched and polished. That sir, is 500 well spent.

 

[xxyauxxdc5]

Decided not to buy it buy thanks for ur input

 

[EddieIt]

i have a skunk2 74mm TB. hybrid racing has a TB with a 74 inlet and a 76 outlet.
should i try boring the outlet of my 74mm to 76mm along with doing the same to my mani?

 

[EddieIt]

i have a 74mm skunk2 tb. hybrid racing sells their tb with a 74mm inlet and a 76mm outlet. should i bore out the outlet of my skunk2 tb along with the mani?

 

[Jordan Dc5]

Ask your GF if she can feel an extra 4mms of rock solid meat......once you get your answer you should relate that to the difference between a 70mm and 74mm TB.

 

[Mrjedi]

Second bump from the grave. I've currently got Injen CAI, RBC, Kpro, stage 1 cams. The driveability suffers a little under 2500 RPM even after the tune. The tuner says the air velocity was lowered by moving to a larger IM and is more pronounced by using the slightly larger cams. I'm great if I keep the RPMs above 2500 (or shift into neutral) - but here are my questions:

I'm installing a K24/K20 frank using 11.5:1 pistons. Will this increase the vacuum where a 70mm TB is now more feasible. I agree that a stock RSX engine doesn't need a bigger TB, but what about after adding a K24 bottom end? Also, is the Injen CAI big enough?

 

[fatso666]

Another bump from oblivion, the last question is interesting for me also because im building a frank also with 11.5.1 pistons too

 

[Ridgeback]

Yes buy a 70mm. Reason they can be found extremely cheap. I found a Skunk2 70mm for $60 new in box.

 

[hylander]

Would a 70mm skunk2 TB or Blox TB be beneficial with a port matched skunk2 pro series mani? Or will the stock TB work just as well? Current set up:

Injen CAI
Magnaflow Catback exhaust
Ktuner

Soon to install PLM Race Header Apr '18.