High Compression Pistons

[Fernandez]

At the end of the sumer the engine is getting modified including some forged internals.

Just wondering what peoples opinions, tech knowledge, benefits and pitt falls there would be with upping the compression ratio to 12.8:1 or even pushing it up to 13.3:1


Clicky 12.8:1

Clicky 13.3:1

 

[fmp]

what else is going with the forged engine? Throttle bodies and cams?

 

[Foxspeed]

think you need to decide what else your doing...

cams and the lift of them will have a baring on the pistons and clearance requirements!

but its normally the "more squeeze the bigger the bang" :wiz:

 

[Fernandez]

Definately going cams but not cat cam or Shrick, got something else lined up there. As for intake I've got a V6 setup waiting to go on but have been chatting to a few people about developing something along the lines of the JMS system but using the bottom half of the std inlet for ease.

My reasons for going forged is that not only would the engine be stronger and happier to rev higher, I would like to run a good shot of nos plus I would like the option of going charged at a later date. I fully understand that to run any kind of boost I need low compression pistons but if I'm having the engine rebuilt I may as well chuck the in the forged rods at the first instance.

I have toyed with the meg engine swap but its just not the way I want to go.

Just wondered what the deal was with a higher compression. What gains could I see and with that and cams would the ecu handle it.

 

[sideways danny]

The trouble is, the originals are pretty high to start with, so you'll notice less difference than an older engine you bump up by a bigger margin

For a road car, any more than 12:1 is going to cause issues, and all you'll be doing with more compression is reducing the available ignition advance and creating more heat.

I'm standing firm on the fact that the F4R in all it's guises likes induction length. I'm still working on the up and over ITB setup as it's the best way to give real gains and not just peak bhp right at the top of the revs (short runners lose bhp and torque through the majority of the revs)

 

[Foxspeed]

Definately going cams but not cat cam or Shrick, got something else lined up there. As for intake I've got a V6 setup waiting to go on but have been chatting to a few people about developing something along the lines of the JMS system but using the bottom half of the std inlet for ease.

My reasons for going forged is that not only would the engine be stronger and happier to rev higher, I would like to run a good shot of nos plus I would like the option of going charged at a later date. I fully understand that to run any kind of boost I need low compression pistons but if I'm having the engine rebuilt I may as well chuck the in the forged rods at the first instance.

I have toyed with the meg engine swap but its just not the way I want to go.

Just wondered what the deal was with a higher compression. What gains could I see and with that and cams would the ecu handle it.

well if your not going daft and want a margin of safety wouldnt go higher than the 12.8

but like most engines its what your after peak power or gains throughout the range and a bit less peak...

for me i would want like a ctr k series an extra 1000rpm say to 8300rpm but without that engines "lack" of low end torque as you still want a driveable road engine but when the need arrises the ability to zip round the rev counter

 

[Fernandez]

It needs to be drivable as you say Si. I'm happy to stick with the standard compression but saw those pistons and wondered what the score was.

Danny: Very interesting what you say about the runner length. The AT Power kit for the f4r does look too short to tbh.

My initial brief was to cam, forge and play with the induction set-up then take it from there with forced induction. Think I will stick with that.

 

[Foxspeed]

It needs to be drivable as you say Si. I'm happy to stick with the standard compression but saw those pistons and wondered what the score was.

Danny: Very interesting what you say about the runner length. The AT Power kit for the f4r does look too short to tbh.

My initial brief was to cam, forge and play with the induction set-up then take it from there with forced induction. Think I will stick with that.

standard psitons will be cast so you still need to change them for relaibility...

i would have a word with rs tuning to see what they can squeeze out of the standard ecu with regards to knock limits and ignition advance etc modern engines arent like old distrbutor systems were you could run a "safe" ignition advance :coffee:

 

[Fernandez]

Would def go forged pistons.

Need to make a few calls and explore the options.

Cheers for the input guys, food for thought..

 

[A2ON]

Meg 250 , Cooler and Map FTW.

 

[Fernandez]

Meg 250 , Cooler and Map FTW.

Dont like em mate, drove one at Silverstone and it wasnt for me, cracking car just not what I want.

I think Supercharged is the way forward for me.

 

[Richy200]

Super charger FTW!!!

I don't like the look of the Megane so a high power clio would be nice.

Although id give everything for an R26.R lol.

 

[Fernandez]

Super charger FTW!!!

I don't like the look of the Megane so a high power clio would be nice.

Although id give everything for an R26.R lol.

You were so close to one too

Has to be high power Clio, even of its just to wipe the smile off some faces.. Lol

 

[Richy200]

Yes! RS focus owners!! Lol.

although its fun making st owners sweat a bit as a clio sticks with them haha.

yeah it'll happen one day! Lol or a 135i haha.

 

[Fernandez]

BMW and Audi owners too..

I reckon a forged supercharged lump with a shot of Nos should shut up a few Scooby and Evo owners, that would do it for me.

 

[Richy200]

260bhp like Mikeys would do it for me!!

 

[Fernandez]

260bhp like Mikeys would do it for me!!

I know what your saying, he's taking me out on track at FCS so can't wait for that. It is, the way forward.

 

[fmp]

k-tec seem to have been getting good result's from thier S/C kit. Should be an off the shelf kit too.

I unfortunately am getting used to the 265bhp mine produces... must resist more power!!

 

[sideways danny]

Danny: Very interesting what you say about the runner length. The AT Power kit for the f4r does look too short to tbh.

so far too short it's almost funny. We did all the length trials with jenvey throttles at Omex and length is necessary.

 

[GrumpyTwig]

so far too short it's almost funny. We did all the length trials with jenvey throttles at Omex and length is necessary.

Ever fitted any up and overs to a 197? I saw an old thread on cliosport with some that had been fitted, it'd be interesting to see some results tbh on an RR.

Random question but any idea if theres room for upping displacement? I know a certain 197 that ended up closer to a 2.1 litre but is there much benefit?