Supercharger And Reground Cams, Good Idea?

[Paul_13 212 1 Cars]

Just a quick question:

 

Engine concerned is a XU10J4RS engine, with a Rotrex high boost supercharger. Going to have 2046cc using wossner 87mm pistons. Standard crank.

 

Now is it a good idea to throw petert regrinds into the equation? If so stage 1 or 2? Engine will be on aftermarket management.

 

Any concern I have is the cams having too much lift and the gases blowing back into the inlet, or straight through the exhaust valves on overlap.

 

Thoughts please

[kyepan 291]

I read that forced indyction camsgaft is a bit different.when turbo charging.. I know thats not what is being done here. Check out maximum boost.com. Its got an article on vauxhal c20let tuning

[rallysteve 22]

I think an inlet cam with more duration is advantageous to forced induction engines

[Batfink 201]

turbos need lower duration cams I believe, but superchargers work with a broader range of cams.

[Paul_13 212 1 Cars]

Thanks for the input

[Tom Fenton 1,526]

With a twin cam engine you are laughing as it is easy to widen the LCA which will reduce overlap.

[Paul_13 212 1 Cars]

Ok, good news

 

(LCA= Lobe centreline angle?)

 

I should get a project thread started for this thing

[Paul_13 212 1 Cars]

Some mixed opinions on the GTI6 forum about this... Surely some bigger duration cams would help!

 

Boils down to money and the mappers patience really

Edited May 10, 2012 by Paul_13

[Tom Fenton 1,526]

If money is no object then go for some different cams. BUT a couple of psi more boost is very cheap to achieve and will probably net a similar gain to £400 worth of cams?

[Paul_13 212 1 Cars]

I do see your point, I will have a chat with him and see what he wants to do.

 

Or he may pop on here and say hello!

[allanallen 528 2 Cars]

I was under the impression that supercharged engines responded well to n/a cams, wether that's just for positive displacement chargers rather than centrifugal ones I'm unsure.

I always find theres alot of good info on this sort of thing on the yank Honda forums. They're 'similar' 16 valve engines and there's ALOT of supercharged ones in the states.

 

reading the thread on the 6 forum reminds me of a few years back when folk on here were adamant boosted 16valvers were pointless and recommended you to stay 8 valve

Edited May 10, 2012 by allanallen

[clen666 2]

 

I asked Petert about camshaft choice for an s/c engine a while ago, he basically said the standard ones are ideal, just adjust them to reduce overlap

Edited May 10, 2012 by clen666

[petert 554]

You can certainly change the cams on a boosted engine. It's all a matter of where you want the power range and how small the originals are. Whilst it is easy to give it a few more psi, there's obviously a limit to that before you need to consider head efficiency and cam timing.

 

I'd either go Stage I inlet/Standard exhaust or Stage I on both. The overlap period is easily controlled with the standard verniers. Just set the exhaust to 0.020" lift @ TDC to begin with, maybe even advancing to 0.010" or 0.000" max.

Edited May 11, 2012 by petert

[clen666 2]

So do you think there is much to be gained by going from standard to stage 1s?

[petert 554]

Definitely!

[clen666 2]

Interesting...!