Race Engine Forum UK

When having throttle plate just at the head entry (lets say 1 inch away) is it better to have it positioned vertically instead of horizontally?

As the throttle will cut the flow in upped and lower part if horizontally, where if positioned vertically it cuts flow on left and right part, just like the valves are positioned. So at WOT this is a good thing, but at part throttle it's not so good as one part will get more air than the other. Or maybe the turbulence created will have good effects?

What's Your oppinion?

thank you

Ziga

That is a very interesting question and I do not know the answer!

GC

I have seen th golf 3 Kit car homologation papers and there are such throttles. I do not know if it gave any additional power but seems to be working good.

A friend had a 155 SuperTouting (D1) a while back, the butterflies were vertical. Never seen it on any other engine but I'm sure there was a reason for it, maybe because the setup proved superior during testing or maybe because the linkage didn't fit, I have no idea.
Injectors were positioned on the upside of the butterflies.

Well yes, I think that the main reason for fitting them like this is the ease of controlling them, and when positioned far up the runner they do not cause such restriction as I have described. However this situation changes when throttles are positioned close to the head entry, or better yet, close to where each valve path seperates.

Anyone else has any inputs?

thank you

Ziga