jcooper97TL

Hi Again,

Does anyone know what actuallay causes the secondary throttle butterflies to open in the 2.5TL intake plenum? I know it happens at 4900 RPM, but I was wondering if there would be any benifit to having them open sooner or at my control.

Go90go

No benefit at all, and it's a 3 stage intake plenum system. Stage 1 is from idle to 3299 RPM, 3300 RPM to 3899 is stage 2, the from 3900 RPM til the engine blows is stage 3, haha. The baffles are vacuum operated and it's been dyno-proven that if you open it up completely from idle, you lose a little power, and if you open it the beginning of stage 2, the power curve shifts slightly (you bog a bit at 3300 RPM up) but you have the same peak power. I tried it a long time ago and it hurt performance for me right after I started the car.

~Cheers~

01tl4tl

I dont have a gen 1- so - is there really a carb with secondaries- like a 4barrel Edelbrock or Holly 650 type? or fuel injected?

The gen 2 has Vtec mode that starts at 4700 rpm- activated by increase in engine oil pressure- it causes the valve timing and lift duration to change, and other stuff I dont know how- but it makes the car go faster.

Go90go

^ VTEC, like you said, uses oil pressure to push a third lobe up out of the camshaft. We don't have anything like that. Our manifold has sections and they are opened up by vacuum to create the effect of longer or shorter runners.

~Cheers~

P.S. Also, removing the system all together and removing the little walls inside the manifold causes turbulence and we lose power. Air resonance and the way each cylinder is supplied was the reason.

P.P.S. Oh, and our TCS system makes it look like we have two inline throttle bodies, but we obviously don't.