Okay, I would have posted this in the "How big is too big" thread but I thought it deserved it's own thread and I didn't want it to get lost.

I have a friend who owns a VW Scirroco. His throttle body is 60mm total diameter, but it is actually two throttle bodies in one basically. When he steps on the gas his throttle cable opens the first one to various degrees, then once the first is open the second begins opening slowly as well.

Could this concept be adapted for our applications and have any benefit?

The reason I ask is because one of the downsides of the 60mm tb seems to be very very touchy response. A progressive throttle body would resolve that, yet still have the same end diameter.

Also wouldn't the smaller size at partial throttle increase the air velocity and give you more torque?


I don't know, I have a headache and I'm having trouble working. Am I just a dumbass? Lock and delete this if I am.

You could make the 60 mm TB throttle opening more progressive with a specially shaped opening mechanism. I don't remember what its called, but its the pulley that the throttle cable hooks into. The stock one is shaped to that the effective diameter of the pulley changes as you open the throttle. So, it takes more pedal travel to open the TB the first 10% than to open the last 10%. I suppose the 60 mm TB already uses something like this. But, if you don't think it is progressive enough, then you could design some sort of more extreme opening mechanism. Thats probably easier than making a dual plate TB.

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

the concept you are taking about is used on almost every carburator. very common.. works very well.. usually it's not needed on fuel injected cars though. if you have an offset size 'barrels', the main purpose is to get extra performance, while maintaining good gas mileage while cruising. I can go more indepth into why carburators NEED the design, while fuel injected vehicles don't. but i'm not gonna type it up unless anyone is interested.

now if you did make a TB that worked like a 2-4 barrel carb (with primary and secondaries) then in the secondaries you could put an N2O nozzel in there and hook it's trigger only to the secondary barrel. this way you could tell when the N2O was gonna go, because there is more resitance from when the first barrel opens all the up, till the secondary barrel opens, traditionally anyway.

in any case. the easiest fix for the touchy gas pedal on the big bore TB's is to make an even more dramtic ramp for the cable to run on, on the TB, like Corbin was saying.

so in a sence you are talking about a cam on a compound bow, how at first it has like 75lbs then the farther you pull the easier the pull, why not use an oblong throttle cable (gear piece?) on the throttle body. instead of the round one we use..