engine compression??

[iain]

looking for peoples advice, me and shaun (grey rs) took the head off my escort today as it was showing signs off the head gasket gone, when the head was off we noticed a fair bit off play in the pistons so going to pull the engine out for a rebuild

my current basic engine spec is

7:2:1 compression
6 long studs
wrc head gasket
port and polished head
bd14 inlet with standard exhaust
gt30701r turbo

was last rolling roaded at 444bhp


what compression would anyone recommend as i would like to raise it again iv done a search and alot off people seem to say to use standard mahle pistons, can i buy these someplace with cut outs already?

[Cossie col]

People say Mahles good to 550 then they tend to use CP pistons. Been told standard compression make a better drive

[Tarmac Terrorist]

Blimey compression that low. Must feel terrible of boost surely? Mines 7.54:1 and does feel weak until the turbos spooled!

[iain]

People say Mahles good to 550 then they tend to use CP pistons. Been told standard compression make a better drive

yeah thats what i thought mate,

[iain]

Blimey compression that low. Must feel terrible of boost surely? Mines 7.54:1 and does feel weak until the turbos spooled!

it wasnt that bad to be fair but its a lazy engine to rev and off boost thats why i want to change

[andyrs]

am nearly 98% sure jimbo says standard pistons with vlve cut out is good for 500? isnt gaz using mahles am hes 600?

[Gray_rs]

Blimey compression that low. Must feel terrible of boost surely? Mines 7.54:1 and does feel weak until the turbos spooled!

I don't think it was that bad,

[Tarmac Terrorist]

I didnt mean bad as such. Lazy is probably the better word, mines the same. I'd like to see what Jimbo would suggest comp wise for gt3076 with the aim of Approx 500bhp and as close to 500ft/lbs as possible, but ained for road car ie not particularly lazy of boost. He'll prob say a diff engine lol!!

[iain]

yes hoping for jimbo to comment and give me some advice lol

[SCS j1mbo]

Here I am

Anything from 7.5-8:1 cr is fine we tend to just drop slightly from standard and run a deep pocket so you can run a big pair of cams if you need to.

Tbh the difference in off boost feel from 7.5-8:1 isn't night and day, cams will make more of a difference.

If you want 500bhp just then 16/std cam would do. To push the gt3076 IMO a bigger exhaust cam is the way to go. We have seen 545 from gaz's

Iain if your going to do it and up the power then I'd have your head ported, change the inlet cam for a 16 and up the cr with standard mahles and pockets

[iain]

Here I am

Anything from 7.5-8:1 cr is fine we tend to just drop slightly from standard and run a deep pocket so you can run a big pair of cams if you need to.

Tbh the difference in off boost feel from 7.5-8:1 isn't night and day, cams will make more of a difference.

If you want 500bhp just then 16/std cam would do. To push the gt3076 IMO a bigger exhaust cam is the way to go. We have seen 545 from gaz's

Iain if your going to do it and up the power then I'd have your head ported, change the inlet cam for a 16 and up the cr with standard mahles and pockets

my head is already ported jimbo forgot to put that in lol, will i notice the differance from 7:2-1 to 8-1?? and also do you guys sell mahle pistons with the cut outs already machined in?

[Tarmac Terrorist]

Jimbo, could you see what Cams I'm running pretty please lol!!

Comp is as said above. Rest of the engine is as you built if for Ripley, just seems very lazy off boost. But that could be down to the map I guess, hence bringing it to you!!

Is between 400-500ft/lb torque a sensible figure to hope for?

[SCS j1mbo]

Iain that's good news mate and yes we could supply mahles machined ready but you would have to dummy build the engine then send them over as we can bowl the pistons to suit cr and put pockets in and top the pistons for the height all in one go.

7.2 - 8:1 you'd notice more for sure

[SCS j1mbo]

Jimbo, could you see what Cams I'm running pretty please lol!!

Comp is as said above. Rest of the engine is as you built if for Ripley, just seems very lazy off boost. But that could be down to the map I guess, hence bringing it to you!!

Is between 400-500ft/lb torque a sensible figure to hope for?

I think 450 lbft is a good target maybe a touch more

It shouldn't feel lazy off boost, I think you may be on a 16/14 as that's a common cam combo we use, we will get her sorted for you

[Tarmac Terrorist]

I think 450 lbft is a good target maybe a touch more

It shouldn't feel lazy off boost, I think you may be on a 16/14 as that's a common cam combo we use, we will get her sorted for you

Helpful chappy!! Cheers Jimbo!
Quite looking forward to seeing the workshop and meeting you guys. I'll have to ring and get it booked in once a bit more cash is sat in the bank.