COLEYST200

iTrader: (3)

As some of you might no I'm planning on putting together a 500 BHP yb motor . Well iv been looking at some wossner Pistons on ebay that all ready have pockets it them and they go up in .25 sizes and have a compression of 8.1
but as iv never looked into this stuff before iv not got a clue . I will be using a twin scroll turbo when the time comes .
Have any of you got any forts on this

Jay,

iTrader: (4)

Hi Dave mine is around 8.6.1 don't get dragged into the have to be low comp to run 500bhp

Caddyshack

I understood they would be all standard comp now.

COLEYST200

iTrader: (3)

thanks mate O I'm Ian cole. Lol

DAN400

iTrader: (3)

ive heard bad reports on here from guys usings wossner pistons on a yb
apparently they are bad for piston slap, but id have thought that would be down to the block not machined correctly
I know of plenty of jap cars running wossners in drift cars etc and having no problems
I saw recently a company on facebook advertising a remake of the original mahle pistons with valve cutouts already in them ,
I have a look to see if I can find there name

DAN400

iTrader: (3)

double post

DAN400

iTrader: (3)

www.modatek.co.uk that's them there

COLEYST200

iTrader: (3)

you could be right there mate about the piston slap . But as the add says they need boring to there spec as there a tighter fit

Jay,

iTrader: (4)

Sorry Ian lol they do slap little at cold just get some mahle a put the valve cut outs in

Bart

I have a nice set of JE 8/1 standard bore size for sale if that would suit you. PM if interested.

stevieturbo

What fuel, what turbo, what ecu, what intercooler etc etc ?

Certainly no reason to go very low, but depending on the above you could go into the 9's

Mid 8's is very safe though these days for most engines around that power.

Mark Shead

Lots of diff things come in to it when judging what comp ratio you need to run for 500hp.

Mark

COLEYST200

iTrader: (3)

Well when it comes time I will be putting on a hart inlet and possibly a 100mm core intercooler as both of these I no can help Big time so any more light you could shed on this matter mark would be fantastic

Adam-M

I once read someone describe Wossners sounding like a skeleton having a wank in a biscuit tin.

nixon_2wd

Its the torque curve you should be focused on, not top end bhp. With the new turbosystems, early boost and volumetric efficiency around 4000rpm means you need to lower the compression ratio to get optimum ignition angle to avoid knock (due to the stoneage sparkplug center ignition system).

Wish we had turbulent jet ignition (TJI) for the YB

3doorcozmess

really? I see a few cars near standard comp achieving good torque and bhp.

stevieturbo

stoneage sparkplug centre ?? WTF

Pretty much every 16v head in existence has the plug in the middle, a very good place for it all things considered.

Caddyshack

Don't tell me that now, I have just jb welded up the old hole and drilled a new one at 38.3 degrees....bugger

Jay,

iTrader: (4)

Lol there is no need to go low comp there are enough cossie's using 8.5.1 and above to prove that fact

mk2cossy

iTrader: (1)

I have Wossner pistons and I get the classic cossy piston slap on cold start up for a few seconds then once warm it sounds very healthy.

3doorcozmess

my thoughts too.

good mapping and efficient cooling low com is fine.

DP motorsport escorts is 700 bhp on standard comp.

turbotrev

Didnt his engine let go though?

Cheers Paul

Caddyshack

I know Cossie Dave is on 700bhp but unsure of the comp ratio...there is a huge difference in a 500bhp engine and a 700 one...as in going from 300 to 400bhp isnt a biggy but pushing past 600 to 700 is pushing the boundaries of so many more factors, there will be far more engine faliures on a 700 engine than on a 500 one.

smiley

Hi mate my 200 block has new cosworth pocketed pistons and shot peened rods comming out as im re speccing maybe perfect will have to check size

turbotrev

Totally agree
And i dont know his comp ratio obviously

Cheers Paul

cossiedave

iTrader: (1)

Didnt really go pop just bent the crank 40tho i was on 7.8.1 comp and 700bhp on bp fuel im higher comp now on the alloy block so may even get more power who knows with a good mapper like i use any thing is possable

cossiedave

iTrader: (1)

still was nailing the shit out of it tho lol

Caddyshack

Are you sticking with standard CC on the alloy block, Dave? If so, is there a reason why you didn't go bigger capacity?

Was that a standard crank that bent? I assume the arrow is going in the new block?

Are you keeping the same head?

cossiedave

iTrader: (1)

Same head same cams 8.0.1 comp yes it was a std crank
Didnt want to go 2.2 as i cant aford all the other parts to go with it lol

Caddyshack

Fair play, if you have the rods, pistons and crank already then I can see why you would stick to standard cc.

I guess you found the limit of the standard crank then!

R4N SS

iTrader: (6)

my 200 block engine is something like 7.6 or 7.8:1 compression so will put as much boost through it to compensate

cossiedave

iTrader: (1)

Some say they have seen 800 on a std crank

ajamesc

I'm using a standard crank and hoping for 650/680 been told the limit of a standard one is 700bhp. Had to get a standard size one ready for my new engine.
Bet yours was savage with the power it had

turbotrev

What caused the crank to bend Dave?

Cheers Paul

turbotrev

What's standard comp?
8.1:1?

Cheers Paul

Jay,

iTrader: (4)

Yes 8 1 Paul

smiley

Bit worrying knowing ones bent so close to your target? Its got me thinking

stevieturbo

Depends why it bent

cossiedave

iTrader: (1)

Iv no idea why it bent just its 25 years old i guess

turbotrev

Out of interest would a lower compression engine be less strenuous on components like the crank, rods, block etc??

Cheers Paul