Throttle bodies

[rev-erend]

Can anyone tell me what happens to the vacuum pipe to the brake servo if you use throttle bodies on an RV8 ?

[trackcar]

You can just run the servo pipe in to one throtle body if you want, the non-return valve in the servo holds a reserve of vacuum so you don't need a constant suck to make it work. On our 8 throttle body base we've made small drillings to link up all the inlets which makes it work better but you don't have to do this is you don't want to.

[rev-erend]

Jules - does it matter that it now contains much more air / fuel than the relatively sheltered position within the regular plenum.

[trackcar]

i wouldnt think that matters , theyre designed to feed into plenums which have are fuel rich when the engine isnt running and they have to cope with backfires into the plenum so i think servos/pipes are pretty hardy as std.

[rev-erend]

OK - Thanks

[rev-erend]

trackcar said:

You can just run the servo pipe in to one throtle body if you want, the non-return valve in the servo holds a reserve of vacuum so you don't need a constant suck to make it work. On our 8 throttle body base we've made small drillings to link up all the inlets which makes it work better but you don't have to do this is you don't want to.

Jules - when you say "our 8 throttle body base"

can't see one on your website.

[trackcar]

it's not finished yet

[v8 racing]

joolz is spot on saying just run it of one cylinder, but depending on if you are running a silly cam this can cause a big problem, i ended up using a vacum pump from a peugeot 205 diesel for my my vacum on t/bodies, very small and easy to mount

[That Daddy]

Never had any problems with vacuum hose running off one cylinder(big servo)and that was a small(in comparison)1720cc Ford Xflow on sidedraught webers with a very spiky long duration cam fitted never exhausted the servo under road use anyway,good luck.

Edited by That Daddy on Thursday 5th June 21:37

[trackcar]

The only time ive had probs is when the one way valve in the servo leaks and you lose your reserve vacuum overnight. As Rob says you can sometimes run into problems with lairy cams and no idle vacuum so with a small valve leak you have to be careful on that first application of the brakes. using a diesel exhauster is a neat touch

[rev-erend]

Rob - so what doe sthis vacuum pump do on the pug.

Are they standalong and electric.. cheap ?

[That Daddy]

Look up Peugeot/Citroen vacuum pump there is one currently on Fleabay at the mo,its the belt driven variety you want(Sorry if i have butted in Rob);)

[tempus]

Why complicate things?just use a small reservoir in line with your single throttle body,inline injection filter works fine.Tempus

[shpub]

John Eales supplies his throttle body setup with the all the TBs linked to form a common vacuum and this connects to what ever is needed:

i.e. MAP sensor, fuel regulator, servo, boost pressure guage.

Had no problems with it at all even when it was NA with a hairy cam.

Most diesels have vacuum pumps of some kind. Some are actually built into the alternator so there is not a separate pulley.

[rev-erend]

Steve

Out of interest - what was the bhp and torque figures for you 5.2 before you went supercharged ?