Cost of lowering compression/FI cam

[Chilliman]

Further to the turbo vs SC thread there are those amongst us who would probably have to lower the CR and change cam before going FI in order to get the biggest power increase benefits (Mac?). I'm intending to get a quote from my favourite engine builder but was wondering if anyone had any ball park figures. There's obviously the cost of LC pistons, and FI suitable cam, but how big a job is this? It can obviously spiral when things are stripped down etc, like maybe new crankshaft bearings, cylinder honing, rocker gear etc etc....

Anyone got any experience of this potentially very costly exercise? Add it the cost of (for example) a SC install and you could probably buy a good fully sorted second TVR for the same money

Thoughts anyone??

[TVR Beaver]

New pistons means new rings.. means a hone of the bore to do it right.. means engine out???…..
Obviously heads off to get them in…
Taking the caps off you should replace the bearings for both rods and mains… As you say… it could start adding up very fast

[SILICONEKID343HP]

What boost is acceptable for an engine with standard pistons and a thicker head gaskets.

Maybe the boost we would be running does not need low comp forged pistons and maybe the cam like the stealth will do the job .

Don`t want to put to much pressure on the old RV8.

[Chilliman]

SILICONEKID343HP said:

What boost is acceptable for an engine with standard pistons and a thicker head gaskets.

Maybe the boost we would be running does not need low comp forged pistons and maybe the cam like the stealth will do the job .

Don`t want to put to much pressure on the old RV8.

I did some some sums on this a while back and worked out I could only use about 4-5 psi boost... based on my 10.6:1 CR. Plus the cam i'm running has a fair bit of overlap so would detract from the extra air going in.. So, 5 psi boost is roughly a third on ambient. Starting with lets say 360 bhp a third increase is say another 120bhp... less efiency losses of say 20% so maybe a gain of (roughly) 95 bhp. End result (maybe) 455 bhp... However, change of cam, going back to single TB plenum might reduce this further.... Maybe 430 bhp. So that's a 70bhp gain for crap loads of money, probably at least 8K ?? worth it? I think not My figures are probably all bks tho so don't take too much notice

Chilli

[SILICONEKID343HP]

Chilliman said:

I did some some sums on this a while back and worked out I could only use about 4-5 psi boost... based on my 10.6:1 CR. Plus the cam i'm running has a fair bit of overlap so would detract from the extra air going in.. So, 5 psi boost is roughly a third on ambient. Starting with lets say 360 bhp a third increase is say another 120bhp... less efiency losses of say 20% so maybe a gain of (roughly) 95 bhp. End result (maybe) 455 bhp... However, change of cam, going back to single TB plenum might reduce this further.... Maybe 430 bhp. So that's a 70bhp gain for crap loads of money, probably at least 8K ?? worth it? I think not My figures are probably all bks tho so don't take too much notice

Chilli

Those calculations would be completly different if you fitted the thicker gaskets .

What boost does TVR Power use on there bolt on SC upgrade to a standard factory engine

Edited by SILICONEKID343HP on Thursday 17th October 20:24

[QBee]

My engine has a CR of 10:1 and a stealth cam.
What are the cost implications and potential gains of an SC?

And the most important two questions:
1. What else will all that power break/ what will I need to upgrade?
2. Can Peter afford to change his car twice in 12 months to stay ahead of me?
3. Should I have stuck an LS in eight months ago?

[Chilliman]

QBee said:

My engine has a CR of 10:1 and a stealth cam.
What are the cost implications and potential gains of an SC?

And the most important two questions:
1. What else will all that power break/ what will I need to upgrade?
2. Can Peter afford to change his car twice in 12 months to stay ahead of me?
3. Should I have stuck an LS in eight months ago?

Love it the most important two questions....

Two kinds of people A

[QBee]

Yup, I hadn't forgotten, R

[fatboychim]

Chilliman said:

Love it the most important two questions....

Two kinds of people A

That was so subtle I hadn't noticed it even though I read the post twice!!