multiple throttlebodies design

[KAM]

Hi guys

Currently I have a set of throttlebodies on my car but I have been offered a set of touring car roller barrel throttlebodies and was wondering the advantages and disadvantages to both systems. Now I havent been impressed with my current setup as I think the inlet manifold is far from an ideal design so am looking at what I can do to get the best out my car.

As far as I know (which isnt much) the butterflies on standard type throttlebodies are easier to balance but can restrict the airflow at full throttle. As my car is for circuit racing is the small advantage in power worth the trouble of making a custom inlet manifold and more difficulty in setting up?

What are the merrits and downsides to each throttlebody design?

Kev

[Notso Swift]

A correctly sized butterfly TB will have very little difference in maximum flow, way less than 1% in power. Now that is important in professional motorsports, but is it for you?
Building a proper manifold, however, may have significantly more benefit than just the Roller TB's by themselves. Better air path, that sort of thing, you could pick up torque throughout the range, far more important than 1 bhp at max revs.
Is it a twin roller type, if so there are basically no downsides. If it is a single, then a little less part throttle control, but again we are talking minuscule amounts

[EfiOz]

Roller barrel throttle bodies have all been plagued with very poor part throttle performance, even the twin rollers ones. The barrels cause very turbulent flow and are non linear in thier throttle progression.

A properly sized butterfly type is still the way to go.

[Notso Swift]

I don't 100% agree when it comes to twin, but I do 100% agree when it comes to singles!

[Chucky]

We had a set here that we were tasked with a view to trying to make work on a V8 application. The flow bench revealed some nasty flow issues.

[Notso Swift]

At (in the most extreme example) 1% throttle opening the air basically needs to do 2 90 degree bends just to make it into the motor with a single barrel design. It is not until 80 degrees that the RB catches the conventional butterfly type for flow (based on the same bore of 45mm) I have seen some actual data on this somewhere, maybe Vizard? Peak flow was only 2-3 cfm more at 10"

However, with a twin it is straight through, so it becomes a case of control and not opening it up to quickly.

[bdwoody]

just wondering if slide throttles are better or worse than the above?

[KAM]

to my knowledge slide throttles are the same but with a different name???
I guess with a touring car they are pretty much driven flat out and the racing is close enough that 1% at full tilt down the straights is worth any problematic issues.