7 replies to this topic

[Mk3vr6/24v]

Hi as the title suggests between the two is there a genuine difference? Or is it a tuning company making up lies for there bad work and engines popping lol I'm aware of the leh having under piston cooling and NO balancer shaft thing, same rods and squeez cast /semi forged pistons, I believe the water ways near top of the bore are prone to breaking cracking, open deck? Which can be wedged? Also has any one got any experience with having a block decked and a limit to it? The a28 will be a long time coming, so at the moment I have a full Z20leh hardly any pressure from a compression test from the infamous cylinder 3 some steel rods and JE pistons p/n 298736 to go in in a c20let there 8.5-1 C/r I believe the old c20let heads combustion chamber is 4cc larger (44cc) and the ecotec is 40cc so a small bump up but as I'm not going to be running massive amounts power 9.5-10/1 CR would be good, Most likely (well I'm going to budget anyway)need to have steel liners if the leh has damaged the cylinder wall, im sorry for all the questions Than you

[Nev]

Z20LET and Z20LEH block castings are the same.

 

The open deck can crack at varying BHP level, I've heard of 3, one breaking at 450 HP and one breaking at 350 HP and one at 520 HP.

 

Wedging the waterways to close the deck a bit is easy with about 1 CM depth of iron dowel. Do the cylinder re-boring after this obviously.

 

I can't remember about the cylinder head CC's (some info on me measuring them here: https://sites.google...-considerations). I have 8.3:1 SCR and it's fine for 30 PSI of boost with plenty of ignition (+22 degrees) and no knock problems. If you plan to use less boost then increase the SCR a bit.

 

Steel liners in the Z20LEx are unusual (and expensive)? Why not just buy a second hand block? I have a spare in my garage you can have, £200.

 

 

Are you planning on sticking this engine in a VX220?

 

Edited by Nev, 24 May 2017 - 08:32 AM.

[Nev]

The Z20LEH crank differs slightly to the Z20LET one, in that it does not have the drive ring gear to turn any counter rotating shafts. Other than that they are are same I think.

[Mk3vr6/24v]

Thank you for the replies and offer on the block It's going in a Zafira, (it seems more mature here for information and attitude) I already have a LET in the car and I can slowly build up the LEH depending on damage It's a choice between new over sized pistons or block lined either way I need it be be close to perfect as will be using low tension piston rings, will ask Knight engine services what they suggest as they will be doing the machining for me and not far from me, now I know what to ask Thank you I've seen a steel lined z20leh break top of bore! 500bhp but no dowels

[Nev]

My dad always used to say 0 gap rings were the way ahead, but this was probably back in the 50s to 70s on NA cars where the temps + lack of boost meant less swelling!  Many/most of the OEM rings are made by NPR these days and I would imagine they are carefully matched for good compression/wear/bedding compromise. Can I ask what's made you select low tension rings for this application please? If you are just doing it to release more power I'd be tempted to avoid them and get the extra power from more boost, otherwise you risk lots of blowby of course. I only mention it as I've had blowby problems before and it's a major headache to fix.

Edited by Nev, 01 June 2017 - 07:32 AM.

[siztenboots]

you can now buy the leh pistons and rings fitted , all pre-gapped for you.

[Mk3vr6/24v]

My dad always used to say 0 gap rings were the way ahead, but this was probably back in the 50s to 70s on NA cars where the temps + lack of boost meant less swelling!  Many/most of the OEM rings are made by NPR these days and I would imagine they are carefully matched for good compression/wear/bedding compromise. Can I ask what's made you select low tension rings for this application please? If you are just doing it to release more power I'd be tempted to avoid them and get the extra power from more boost, otherwise you risk lots of blowby of course. I only mention it as I've had blowby problems before and it's a major headache to fix.

Efficiency, I see it being easy to get 3-400 bhp, drop compression bigger turbo up the boost usual bolt ons Obviously not taking the cost in to consideration When you create a vacuum in the crank case you get better ring seal a reduction in blow by So you can use low tension rings I've used total seal rings with great results in an Honda b18 , I could stand a pound coin on the started engine and it'd stay put, yes very nicely balanced it was I'm not trying to reinvent the wheel just want some power with excellent efficiency as I'm tight lol

[Mk3vr6/24v]

you can now buy the leh pistons and rings fitted , all pre-gapped for you.

I think most standard/ over sized oem spec pistons rings are pre gapped nowadays