Low comp pistons

[SILICONEKID343HP]

If I wanted to swop for low comp pistons would the block need to be re honed or can the original rings be fitted on to the new pistons ?

http://www.v8tuner.co.uk/product.php?id=875

Edited by SILICONEKID343HP on Saturday 12th October 18:46

[carsy]

I`m assuming your thinking about FI Daz.

Assuming your rings will fit these pistons i dont see why you couldnt just swap the rings, assuming you can get them off without braking them.

Do you know what heads you have Daz, as in early or the later 4.0 / 4.6 heads. If you have the later heads, swopping to a pair of early heads would lower your cr a bit.

early heads are 36cc, late heads are 28cc.

Another alternative is to sell your engine complete and then get an ebay 4.0 or 4.6 at 9.35:1, refresh it and then blow on it.

[SILICONEKID343HP]

I have v8d stage four heads and the comp is 10.0:1

I know there is more than one way to skin a cat ,some more expensive than others .

I`m not going to take the engine to it`s limits so not sure if I have to start spending money on forged pistons etc but at the same time I don`t want it to be a bodge ,not sure if spacer gaskets are good enough .

What is the most effective way to lower compression without braking the bank and at the same time I end up with an engine which lasts .

[BuzzBillsberry]

Speak directly to Ray or Shaun at V8D to get your definitive answer. Simples

Buzz

[BuzzBillsberry]

Speak directly to Ray or Shaun at V8D to get your definitive answer. Simples

Buzz

[rigga]

Id never reuse piston rings in any engine of mine. New piston new rings.

[SILICONEKID343HP]

Do they unscrew ?

[spend]

1. You probably want different rings with different gap clearances for FI.

2. Your pistons are'nt rover ~ Rob's 'special 5.0 recipe' uses Rods with Chevy little ends IIRC so you certainnly need to get pistons from Rob, he knows the pins used and compression height hence can get same pistons with different bowl... for your 'special' requirement.

[phazed]

Neal was running compression plates with twin turbos and didn't have a problem.

[neal1980]

phazed said:

Neal was running compression plates with twin turbos and didn't have a problem.

just use arp studs and never had a problem. Engine still going strong today and owner is delighted.

I was in 2 minds to use them or not after reading some things on the net....

got mine from Ferriday engineering got the receipt somewhere if you need more info.

check there website

[mattrosersv]

Cheers Neal, still running beautifully and running it as an everyday car at the mo. Toying with chucking my 500 heads on over Christmas. Don't think I ever asked what CR you built the motor to, can you remember?

Matt

[SILICONEKID346HP]

spend said:

1. You probably want different rings with different gap clearances for FI.

2. Your pistons are'nt rover ~ Rob's 'special 5.0 recipe' uses Rods with Chevy little ends IIRC so you certainnly need to get pistons from Rob, he knows the pins used and compression height hence can get same pistons with different bowl... for your 'special' requirement.

What pistons do I have ?

[phazed]

SILICONEKID346HP said:

What pistons do I have ?

You need to ask Rob. He's the only one who knows for certain.

You could change your heads and sell yours to help fund the FI, stage 4 are about £1,800 iirc.

I'd be inclined to fit decompression plates and fun a sensible boost.

[SILICONEKID346HP]

phazed said:

You need to ask Rob. He's the only one who knows for certain.

You could change your heads and sell yours to help fund the FI, stage 4 are about £1,800 iirc.

I'd be inclined to fit decompression plates and fun a sensible boost.

I thought if I were to remove the heads ,they would be re worked rather than buying FI ones . I spoke to Peter Burgess some years back and he said the best way to lower compression is head work . He gave me some complicated explanation I did not understand .