Best intake manifold?

[Rob H@RCH Engineering]

The bigger TB would give much better response also... but yes the stock item will flow well enough for alot of power...

But Burny is after alot of power... so.. lol

In what way do you mean it will give better response? How are you measureing the response because by response it can mean a lot of things, but from what your saying it sounds like race tech may have measured this. Hence me wondering how it's been measured. Which I'm sure you'll agree, is a valid questions to your statement

[Socks]

In what way do you mean it will give better response? How are you measureing the response because by response it can mean a lot of things, but from what your saying it sounds like race tech may have measured this. Hence me wondering how it's been measured. Which I'm sure you'll agree, is a valid questions to your statement

BIgger butterfly would surely allow more air in as it opens up as you put your foot down!? Providing the engine can make use of it!

I recall putting bigger tb's on fiestas back in the day. Big Improovement.

Ino thats NA tuning rather then Boosted... But Still!

[rorenapier]

Bigger the area to fill (bigger butterfly) the slower the air speed gets.

[StuDoc 72]

BIgger butterfly would surely allow more air in as it opens up as you put your foot down!? Providing the engine can make use of it!

I recall putting bigger tb's on fiestas back in the day. Big Improovement.

Ino thats NA tuning rather then Boosted... But Still!

He is right though you stick a focus throttle body on a fiesta it made a big improvement on those. Dont know if the same applies to boosted tho.

[morgey]

The main increase in air speed would be from the intake runners, my 4age with stock 45mm itbs had an 80mm hole on the intake plenum standard.

The bigger the tb the easier it is to fill the plenum chamber meaning less vaccum therefor easier for it to rev up i.e more power but prob less torque.

This is however just my thinking not proof in any way ;)

[rorenapier]

Im not saying there is not a power gain, im saying the air speed will be slowed down..

Quick scenrio

blow through your lips if you were whistling, and have your hand 6" away

then try it with your mouth open and see the diffirence.

Simple stuff this.

Regardless of N/A vs F/I, same principle applies.

If adding a bigger throttle body was as easy, everybody would be running 100mm plus would they not ;) Ever thought why they dont...

[Ricky@Race-Tech]

The main increase in air speed would be from the intake runners, my 4age with stock 45mm itbs had an 80mm hole on the intake plenum standard.

The bigger the tb the easier it is to fill the plenum chamber meaning less vaccum therefor easier for it to rev up i.e more power but prob less torque.

No it wont.

The air speed needs to be kept up not slowed down. ;)

Just have a little think about it.

But aftermarket manifolds are only really needed when the stock item become restrivctive, which is out of most peoples reach power wise.

Very true, smaller throttle body, higher back pressure less efficiency highe gas speed. Gas speed at the throttle body has no advantages.

Big TB don't give response in general....on the contrast, it makes it more on-off state, as with small increases in the plate angle the opening is becoming bigger.

Unless you run a proper managment, big changes in TB size are not good for drivability.

Again correct, a bigger throttle body gives the appearance of better throttle response when infact it is just flowing more air at lower throttle positions.

In what way do you mean it will give better response? How are you measureing the response because by response it can mean a lot of things, but from what your saying it sounds like race tech may have measured this. Hence me wondering how it's been measured. Which I'm sure you'll agree, is a valid questions to your statement

Very hard to measure, transient responce should infact be worse due to the larger plenum volume. However it is virtually none exsistent, ours takes 0.02 seconds longer than stock to fill at approx 3000rpm's. Compare this to the average boost pipe which is 0.1 seconds.

The main increase in air speed would be from the intake runners, my 4age with stock 45mm itbs had an 80mm hole on the intake plenum standard.

The bigger the tb the easier it is to fill the plenum chamber meaning less vaccum therefor easier for it to rev up i.e more power but prob less torque.

This is however just my thinking not proof in any way ;)

This is however just my thinking not proof in any way ;)

Pretty much correct, your always making a compromise to some extent. We offer completely custom intakes, but most are made for the over 300hp mark which is where your going to get the gains anyway. There shouldn't be any loss of spool time, and on a td04 setup or bigger you should gain spool to top end. You will lose torque off boost and at very low RPM's.

[Ricky@Race-Tech]

Im not saying there is not a power gain, im saying the air speed will be slowed down..

Quick scenrio

blow through your lips if you were whistling, and have your hand 6" away

then try it with your mouth open and see the diffirence.

Simple stuff this.

Regardless of N/A vs F/I, same principle applies.

If adding a bigger throttle body was as easy, everybody would be running 100mm plus would they not ;) Ever thought why they dont...

Indeed, the only reason is for control. A 100mm throttle body would give 100% power at 20% throttle on a stock starlet.

Something else to notice doing that experiment, notice the temperature change of the air also.

[H_D]

if your lookin to run 400bhp+ then go for a bigger inlet manifold and TB if not then there is nothing wrong with the stock one its more than capable!

[AdamB]

Theres only 2 people on the powerboard that would gain an advantage of running a larger inlet and throttle body. Spuddy and Alan, and even then I'm sure Alan is running a stock intake manifold at 440bhp!