I may have asked this before...

[ChilliWhizz]

But my memory really is crap...

Serious question for the turbo boys, what cam are you using? I'm thinking if you've gone for a straight bolt on you're probably running your original cam... Or if you did a rebuild you may have taken advice from those who know and put in a cam that optimises all that boost..

I have been given to understand that big overlap cams (like what I've got) aren't ideal for running boost, coz you lose a percentage of the extra air being forced in whilst the exhaust valves are still open when the pistons have started heaving there way back up the cylinders..

Anyhoo, without going too technical, what are you running and has anyone been recommended an ideal or optimum cam for forced induction applications?

Thanks in advance,

Chilli

[Pupp]

Why do you think there would be more losses with a turbo than NA for any given cam (clue, think how the compressor is driven)?

[cinquecento]

I was using a v8D stealth in the NA days and changed to a MC1 for FI. Very happy with both choices.

[Pupp]

TURBO he said

[sapper]

I'm still on the original cam, I looked around at the time of getting the turbo done but didn't fine any one (cam) that offered any gains that would make a huge difference once the turbo was fitted , I left well alone.

[ChilliWhizz]

Pupp said:

Why do you think there would be more losses with a turbo than NA for any given cam (clue, think how the compressor is driven)?

It was explained to me some time ago, but here's something I've randomly pulled off the net that also explains it (a bit).. It was also explained to me (up to a point) by the bloke that built my engine

....Turbo's produce much higher exhaust pressure than intake. During overlap, exhaust reverts into the intake port. The alleged problem is that exhaust dilutes the intake charge, but I could argue this either way. Testing has revealed that adding overlap to turbo cams increases power, but the testing stopped at about 5 deg. I've venture to say that up to 10 deg of overlap should help power, maybe much more.....

So, slightly conflicting views, kind of suggests that overlap with a supercharger might not be best but same rules don't apply with a turbo because of higher manifold pressures...

So, might get away with just a new set of LC forged pistons

[Pupp]

I don't think there's many road going RV8s with more overlap than I'm currently running, and it's not an issue with the turbo. And don't forget dynamic CR will be lessened over notional static proportional to the overlap; so low comp pistons are not an absolute necessity either.

Really depends where you want the power to come in and how but, in general, whatever characteristics your given cam displays, a properly sized turbo will just accentuate.

[ChilliWhizz]

Pupp said:

And don't forget dynamic CR will be lessened over notional static proportional to the overlap; so low comp pistons are not an absolute necessity either.

I need more info Pupp... Could this just be a case of bolt on a turbo, do a re-map, fit knock sensor then slowly wind up boost and see how we get on?

Could it really be that simple?

Anyway, here's a small celebration just in case...

[phazed]

Do you really want a turbo or just the tee shirt

You have a great car way faster then most, (not mine of course ) just walk away..............................

All that time at sea, drop PH and pick up the top shelf mags

[ChilliWhizz]

phazed said:

Do you really want a turbo or just the tee shirt

You have a great car way faster then most, (not mine of course ) just walk away..............................

All that time at sea, drop PH and pick up the top shelf mags

Sorry Dad, it was the wine talking... won't happen again...

[N7GTX]

Camshaft E0158 was fitted by Powers on my little 4.0 installation.

http://www.powersperformance.co.uk/store/slug/4-lt...

[SILICONEKID345HP]

Can`t you just drop the pistons out for low compression ones ? I`m still not understanding how balancing works .

[Alexdaredevils]

ChilliWhizz said:

Pupp said:

And don't forget dynamic CR will be lessened over notional static proportional to the overlap; so low comp pistons are not an absolute necessity either.

I need more info Pupp... Could this just be a case of bolt on a turbo, do a re-map, fit knock sensor then slowly wind up boost and see how we get on?

Could it really be that simple?

Anyway, here's a small celebration just in case...

Pretty much mate.

My LS is massively cammed 10:1 and twin turbo and i'm not worried at all