26 replies to this topic

[jaydee]

You have to run premium or vpower only, and personally i wouldnt go over 10,5:1 CR, unless you want to race the car.
The problem is that you choose a 940 head instead of the 295, which has more cc in the chambers and its the perfect cylinder head for a 1100. With the head gasket you gain 3,8cc only..do you have flat top pistons? Maybe dished pistons can help, but to be honest i dont know what pistons are available for a 1098.

(well i've edited tons of typos i made lol..)

Edited by jaydee, 02 July 2009 - 10:28 AM.

[liirge]

Yer thats what i was thinking, i was hopinf 10.5 would be good, but no ive managed way over that!
It not a 1098 its a 1096, a strange size due to the overbore, i havent stroked the engine, ive just overbored it.
so 1098 pistons wont fit.
They are flat top, could i get some work done to the head to reduce the C\R to maybe 11:1.

[1293sleeper]

you can alway buy a thicker head gasket but they tend to be very expensive

[liirge]

What High Torque motor did you get Sleeper?

[jayare]

It looks like you may have missed my post earlier in the thread (you were replying at the same time) - you haven't allowed for some of the volumes - ring land volume, volume above piston at TDC and the pockets in the block. If your pistons stop 50 thou down the bores, you immediately gain an extra ~4cc. If you have ~1cc pockets, that gives an extra 5cc to the chamber, bringing the CR down to 10:1

JR

[1293sleeper]

this is the one i have on order
http://www.minispeed...c...ct&id=lms10

[liirge]

I forgot about the Pockets your Right, the Ringland ive been told is usually about 0.7cc. I dont know how far short the piston is off the top of the surface of the block. Can i only find this ut when the Engine is built up?

[liirge]

hmm starter looks tastey

[1293sleeper]

if i was you i would build the engine and see where you are when you come to start it if you need the motor then get it and if not then your all good. sounds like a it'll be a fun engine.

[1293sleeper]

yeah they do look good i wasn't to sad when i found out i had to get one

[liirge]

ha ok when i build the engine i will find out how far the piston goes up in relation to the block surface

[jayare]

I forgot about the Pockets your Right, the Ringland ive been told is usually about 0.7cc. I dont know how far short the piston is off the top of the surface of the block. Can i only find this ut when the Engine is built up?

Yup - do a 'dry' build without piston rings, etc just to see how your clearances stack up. You can sometimes find a bit of difference in the piston to block height across the four pots and by swapping which rod/piston is in each cylinder you may be able to even it out. Once you know your piston to deck height, you can get the block decked if need be to increase the CR (probably not in your case - just get the bare minimum skimmed off to make sure it's flat).

Not sure how you'd work out your pocket volume - probably using paper & some maths to work out the area of the cut-out!

JR