Throttle bodies slimming the shaft

[justinbaker]

I remember doing this to an old twin carb midget after reading David Vizards A series book. It seemed to make a difference on that engine. It would be interesting to see this done on the speed six throttle bodies, and the results displayed on Austec's Dyno.


I have just sketched up on Inventor the image below, a throttle shaft that I removed one side of, and thinned the other, with a countersunk the throttle plate.
There would be more air entering the engine at full throttle as there isn't so much shaft in the way.

Those screws would need 'loctite' as they would make a big mess if they were swallowed.

[pic]http://www.racecarlivery.co.uk/throttle.jpg[/pic]

[chevtrev]

I'm no expert,but you could also knife edge the intake side of the butterfly.
Better still port the throttle body within a thou of its life and make a new butterfly.


edited cos I did'nt read/look at Justins post properly..

>> Edited by chevtrev on Tuesday 20th September 10:58

[GreenV8S]

For an engine like that, I would have thought that slide throttles would be worth having.

[cerber450]

I've already done this to mine but I have no idea if its done any good yet or not! As weve not tuned her up yet.

[trackcar]

I have results from this on ajp8 .. after doing the induction we were chasing the last 3hp to get 400hp at nobles, I did the throttle spindles, and smoothed all the inlets down to the back of the inlet valve. gained the 3hp so worth the effort for us but you'd not want to repeat it for a customer unless they absolutely insisted! If you have time on your hands though every little helps

This is on a ajp8 though, a sp6 runs larger butterflies i think so the gains would be minimal to zero i would imagine.