Contour Enthusiasts Group Archives Forums Modifications Duratec Performance 70 MM Throttle body.

I know why he used it...

Because it acts like intercooler pipe size does. A larger diameter "throttle body in this instance" would decrease the amount of boost generated (or PSI drop) and also increase the boost lag.

This is another example of when larger isn't always better.

Also this only applies to forced induction engines. A N/A engine pulls air in and then a larger opening would allow for more air flow. Velocity & pressure drop are not a factor.

Actually, boost is only a measure of back pressure. If you open the intake and lose 1# of boost, are you getting any less air in? No, you are getting more air in, just less back pressure.

Please don't correlate more boost = more HP. More boost does = more backpressure.

Regards,

ding ding ding

The best example in recent memory of this is when we did a headswap on a Vortech'ed 4.6 2V Mustang a few months back. The car was running ~9lbs with stock 97 heads, and after the swap to ported 99 heads it dropped to ~7lbs, due to the significantly better flow of the heads. Naturally, HP went up even with a reported loss of boost.

Mmars, I am sorry to be rude, but I KNOW you're wrong.
Yu are tryng to tell me that Mustang owners need to modify their throttle cables when going from a 65mm TB to a 70mm TB?. I don't think so (I know so!) as that mod is supposed to be a plug in plug out. I think I smell BS! :rolleyes:
And if you don't believe me, read this: http://www.corral.net/tech/powerplant/sohctb.htm
Trust me if you CLOCK the throttle shaft and cam through 180° (for fitment to a Contour), I assure you NO MOD TO THE THROTTLE CABLE IS REQUIRED, as the throttle cam will be in the EXACT SAME POSITION AS THE CONTOUR REQUIRES. I've done it.
I think you don't realise what "clocking" means. I am not talking about flipping the TB upside down to hae the throttle cam facing the firewall, but rotating the shaft to flip the throttle cam upside down.
Like I said before to someone else. READ MY INSTRUCTIONS FOR FITTING A 65mm TB CAREFULLY , LOOK AT THE PICS and you will see that the Contour throttle cable can be used "as is".

Lol - ease off Aussie and MMars, I'll try that this weekend with my 70.

So Aussie - you did say pedal throw is not any shorter with your 65?

Thanks,
Dan

With the bracket on the throttle cam adjusted so that it makes the dead stop (@ 90°) on the intake manifold. You lose maybe 1" off the floor off total pedal throw.

Thanks Aussie, that sounds better than what I have now, which is that the throw is less than half what it should be. Actually had me contemplating fitting a motorcycle grip.

dan

Mmars, I am sorry to be rude, but I KNOW you're wrong.
Yu are tryng to tell me that Mustang owners need to modify their throttle cables when going from a 65mm TB to a 70mm TB?. I don't think so (I know so!) as that mod is supposed to be a plug in plug out. I think I smell BS! :rolleyes:
And if you don't believe me, read this: http://www.corral.net/tech/powerplant/sohctb.htm
Trust me if you CLOCK the throttle shaft and cam through 180° (for fitment to a Contour), I assure you NO MOD TO THE THROTTLE CABLE IS REQUIRED, as the throttle cam will be in the EXACT SAME POSITION AS THE CONTOUR REQUIRES. I've done it.
I think you don't realise what "clocking" means. I am not talking about flipping the TB upside down to hae the throttle cam facing the firewall, but rotating the shaft to flip the throttle cam upside down.
Like I said before to someone else. READ MY INSTRUCTIONS FOR FITTING A 65mm TB CAREFULLY , LOOK AT THE PICS and you will see that the Contour throttle cable can be used "as is".[/QB][/QUOTE]


Ooooohh....I see what you mean now. I didn't realize that you turned the cam upsidedown.

Thanks for being rude.

--Matt

A turbo's CFM rate is directly related to it's psi level. (boost) (Why turbos are rated like: TD-05H-20G ~ 650CFM@15psi)
Thereby when lowering the boost achieved the turbo's CFM rate drops as well.
I never made mention of horsepower anywhere.

However. If you'd like to...

Set engine makes 300HP at 6psi.
Same said engine will make more horsepower at a higher boost level.

Now a different engine at 4psi might make 400HP. But that's not the same engine (or one with different heads)

more boost = greater cfm capability = greater power achievable