can you tell the compression ratio by filling up the bore through the spark plug hole when the engine is at tdc ?

 

i know this sounds stupid,but i had my pistons machined,lower compression and valve cutouts,and i can't remember what it was,think it was 7.5.1.
The plan was to have it live mapped by the chap who had all the engine parts machined for me,as he speced my engine for about 380-400 bhp,but i now want an msd chip.They said was going to run light blues on t34.48

 

what engine are you talking about? YB?

if so; what is the bore measurement

 

yep,its a yb,1st oversize

 

who machined your pistons ?

 

 

dont think we have many light blues files for off the shelf application, i would go 55s, as for CR, if its unknown ideaaly live map it.

 

I,m not sure who machined them,i just gave a box of bits to the chaps,and had it all back done.

 

 

I'm certain it was 7.5.1,i might give them a ring,hopefully they won't get the arse.
What sort of power would an msd chip be.

 

on a t34 48, flat out 360-370

 

and the rest james, we have done plenty on the dyno above that

im sure you guys can get a bit more

 

not off the shelf, we never over quote figures, if they make more so be it

i pushed my .48 very very hard, and saw around 380bhp/420lb/ft, they just run out of puff too early for much more than that

 

does lowering the compression make a difference on the power output from standard,i was told it would stop detonation

 

ok fair enough, a recent engine of ours did 380 something cant remember exactly on an off shelf chip so thought you were being a bit conservative there mate better than being over though

 

going back to msd,does it make a difference to the programming if it were 7.5.1 or standard 8.1

 

we could easily do your turbocharger chioce on std comp

 

yep, the pistons in your pic are certainly not std CR

 

exactly mate, i love the .48, ace road spec mine used to get a bit hot at 36psi though

 

The problem is,where i want to take it to be live mapped,they do it on the road,when its dry they are to busy,they quoted me 380bhp,but if msd can match that with a next day delivery and a set of siemens,then its got to be msd !

 

i bet they didnt last long lol

this is what i want im my saff first, makes such a nice road engine !

 

did 75k miles on one turbo belive it or not! never gave any trouble!

apart from killing 3 gearboxes in a year

 

lucky with that one ! some last a couple of months

yours was 4x4 was it ?

 

who were you going to take it too; quite a few capable people round kent way

 

yeah, i had to get a bara box on it

 

If you ask MSD to do a chip for a 7.5:1 engine and you get a couple of cracks of det then use the octane switch to take a couple degrees of ignition out. You arent going to be that far off the mark with your c/r are you. Not like its going to be 8:1 and you are thinking its 7:5.1.

 

yep,never thought of that,how much difference does it make having the valve cutouts on cr,assuming all other aspects are the same

 

iirc valve cut outs make 0.2 difference

 

mine have the valve cutouts done,and the dishes are very slightly bigger,compared to my old pistons,but only slightly bigger

 

the grove did all the running round,great blokes,just mega busy

 

phoned up today,def 7.5.1.
what sort of power should i expect t34.38 ?

 

A realistic 360 - 370 bhp i reckon.

 

that would do for me, in a 750kg car

 

 

I would say that is plenty yes mate