Estimated power projection?

[2mad]

he's only got 9.0:1's aswell !

[Poker Face]

I'm going for Wössner pistons on my engine rebuild, they are available in 86, 86.25, 86.5 and 87 comp ratio 8:1 and are around 500 quid not sure if that is inclusive of vat but I think so.

I'm sure Bob listed some 8:1 comp pistons on one of the threads started by Sheppy prior to him starting his build.

[drchandra9]

hmmm. it seems a lot of people are using 8.0-8.5:1 on their builds. have i made a grievous error buying 9.0:1's? is anyone running the same c/r as I'll have? all advice is welcome guys! thanks!

[MR2 Rich]

When I was researching CP Pistons I read (probably on here/link from here) that the CP's are 8.5.

I will try find the thread, I'm sure it was a compression ratio thread with loads of pages, sound familiar to anyone?

[MR2 Rich]

Here's the thread;

http://www.imoc.co.uk/forums/viewtopic. ... sion+ratio

[drchandra9]

yeah i read that thread too. it says with a 1mm gasket the c/r will be 9.0:1. for cp's. i didn't want to mention using a thicker head gasket because of what this thread said!!

[MR2 Rich]

yeah i read that thread too. it says with a 1mm gasket the c/r will be 9.0:1. for cp's. i didn't want to mention using a thicker head gasket because of what this thread said!!

The way I read it, CP measure the compression ration with a 1mm head gasket (giving a ratio of 9.0) but the standard Rev3 head gasket is 1.4mm giving a compression ratio of 8.5?

[drchandra9]

aaah i see! i thought (stupidly) the standard hg was 1 mm!! so i guess i need to get a 1.4 mm hg.makes a bit more sense now. thanks buddy. now to source that gasket........tcb methinks!

[MR2 Rich]

I got all my Toyota parts for my engine from TCB, good prices and great service.

[drchandra9]

yeah I've used him over the years! top bloke!

[bobhatton]

I'm going for Wössner pistons on my engine rebuild, they are available in 86, 86.25, 86.5 and 87 comp ratio 8:1 and are around 500 quid not sure if that is inclusive of vat but I think so.

I'm sure Bob listed some 8:1 comp pistons on one of the threads started by Sheppy prior to him starting his build.

Yes, we can get the 8.0:1 wossner pistons if you want some. We try and not bore the block, just hone it check the clearance and away you go

[bobhatton]

aaah i see! i thought (stupidly) the standard hg was 1 mm!! so i guess i need to get a 1.4 mm hg.makes a bit more sense now. thanks buddy. now to source that gasket........tcb methinks!

The important part of the build is the piston to head clearance. That needs to be 1mm, any bigger and the engine will be prone to detonation.
By increasing the compression ratio you will have to run less boost or back the timing off, both of them will drop the power of the engine.
I would go for the 8.0:1 pistons, we have proven that is the right way to go on a number of builds.
With a rev3 ecu you can get around 325 hp with a ct20b turbo

[drchandra9]

thanks for that bob. only thing is my pistons arrived today!! while your here, am i doing the right thing sticking to a standard rev3 hg?

[MR2 Rich]

thanks for that bob. only thing is my pistons arrived today!! while your here, am i doing the right thing sticking to a standard rev3 hg?

The standard Toyota Rev3 head gaskets are very good, it will be fine. The Rev1 and 2 are poor compared to the metal Rev3's.

[drchandra9]

thanks buddy! that's put my mind to rest! it's my first forged build so im a little apprehensive.

[Poker Face]

Couldn't you just return the Pistons and get some Wössner ones?

I suppose if your halfway through the build you want to crack on, I am guessing you already have the head stripped down.

Anyway whatever you decide/ do good luck with the build.

[bobhatton]

thanks for that bob. only thing is my pistons arrived today!! while your here, am i doing the right thing sticking to a standard rev3 hg?

The rev 3 gasket works great, but you must get the piston to head clearance right, 1mm no bigger.

[drchandra9]

thanks for that bob! if this is the most important consideration then i will take care to get it spot on. im quite happy to turn the boost down as my ct20b is quite old and i don't want to push it until I've found the right turbo.