right then, it looks like ive soursed an sti v7 block

so what i need to know, is the head gasket thickness i need
im fitting a set of sti v4 heads

in with the price, the guy is putting a set of 1.0mm comatic head gaskets in with the deal

and i have a set of 1.6mm comatic head gaskets
which will be best to fit.

the engine is going in my uk classic.

 

depends on your desired upper boost level,for high boost levels you'd be better with the thicker 1.6mm HG due to it lowering the comp ratio a little, normal to mid boost go with the 1.0mm but really you need to discuss it with the guy who's building it, decide what you expect from the build and tell him to build it to suit, it, make sure he's building what you want.

 

And use a subaru specialist for your eng build. all to often on forums you read about people building engines and not to long after there having problems. Its worth the extra dollar

 

the last subaru engine, is still going strong.
even the first one i did which was over 2 years ago, is perfect
its in my car still, it was a uk engine, but i fitted sti v4 pistons.

i can build engines duck
i just need to know if a 1.0 or 1.6 will be best, for the sti v4 head and sti v7 block. due to compresion values


jgm will be mapping my car again, so the boost will/should be around 1.3bar as i fitted a 1.7 map sencer to my early classic

 

If you can build engines work out the compression ratio of the two diffrent sizes of gasket, head combination & you will have your answer.

 

^^^^oh now that was a cheap shot

 

As motors says, always best - wise! - to try to choose the thickness that will try to restore as close as possible the factory std compression ratio (with respect to the heads/pistons/rods being used). IMO.

 

i dont know, some persons.
the fact is, becouse im using sti v4 heads.there will be a differnt comprsion ratios.
compaired to the whole sti v7 set up.

tuners may/will have done this combo, so asking advice is best.
im not a specialist in this, i just know how things work.
from my first car to know, i've always done all engine work.
alot of tuners may not know the exact compresion.
but can build a cracking engine.

still, thanks for the replys guys
i'll have both 1.0 & the 1.6mm gaskets
i'll do some more reserch before i mate them

 

I have looked through a few of my last builds for head figures V3 heads 49.8cc, V5 49.5cc, UK hyd heads 49.4cc, early cloverleaf shape combustion chamber heads 46cc, the last V5 i did with V5 heads, Mahle pistons used 1.1 Cometic gaskets gave a total of 8.02:1, it makes a diffrence if valves & seats have been re cut.

I would stick with the 1.0's if it was me, as your getting it mapped i would'nt worry if the comp is slightly higher, it will help spool up & be slightly better response off boost.
I have a lot of info on 2.5's in particular late AVAC's heads & engine combo's.

 

nice one.
im looking forward to starting it.
picking the short engine up next week, then starting it.
i havn't done it this way for the power side, as the engine will be running around 340/350

its strenth really.
dont want it to just go bang.

thanks for that mate, i'll post up the out come.

 

If cash ain't no problem, have you also considered std sized 11mm uprated ARP head bolts? Around £150.

 

got them
arp studs to be exact mate.
the person im getting the block off, already had the gasket and arp studs.
the sti v4 heads i have were completly serviced.

the car should go quite well.

 

Okay okay (not 'thinking' on my part)

 

its ok mate, i said the same when i asked about them

looking forward to next week when i start rebuilding this engine.
got a set of rear 2 pots, which im doing in gold to match the brembos i have on the front

then its mapping time, jgm will do his magic on her.
got a set of 500cc blue injectors imported from japan.
may just stick to the td05 16g.

but was tempted on an 18g, and having the inlet adapted for the 90'
just need to make sure the 1.0 will be fine.
i did have compresion issue, with the uk heads mixed with sti v4 forged pistons.
so hoping this combo, will give more bottom end grunt