HKS or ND pistons

[sypher]

hey guys can u tell me your thoughts on what r the best pistons, i need an oversized set and found the N D ones but don't know if HKS do +1mm. Can u tell me what u guys r using and what u recomend... thanks

 

[ashills]

im using hks 1mm oversize very good pistons with a coating or treatment on teh crown
quite as a mouse seem perfect if u want to save loads of money get a set of cp or ross from the states very good quality and half teh price

 

[sypher]

thanks for trhe reply i will keep the forum updated with me progress and pics of my buggy if i figure it out coz i've never used a turbo at crail let alone a AWD thanks again

 

[Anonymous]

ND uses the

JE pistons as I had them put in my old car (britts has her now)

I think they are standard size as did not have to have the block re bored.

JE seem to be very good pistons as like HKS.

is there any issues with over size as do you lose some of the integral strength of the block?? I guess if you use the liners with the HKS ones them you have a very nice set up!!

 

[Anonymous]

Norris uses JE Pistons forged +1mm o/s, they are from America, and have a good rep

 

[J-GTi-R]

They are JE pistons, but built to ND's spec. They're pretty low compression though, great if you want to run 1.7 bar etc., but not ideal if you're not running mega boost.

 

[Sirnixalot]

the lower the compression the more boost you can run without having to worry about detonation....you dont have to be as specific with the tuning either.

But ho the hell would want 7.8:1 CR?? Pointless if you ask me. I challenge you guys to think outside the box and RAISE the compression ratio.

Standard is 8.3:1. Get a set of 8.5:1 pistons and a Tomei 1mm head gasket which will raise it another 0.2 points. Or at least get the 8.5:1 pistons and 1.2mm or 1.5mm headgasket.

Personally i will be going for 9.0:1 and with the 1.2mm headgasket it will be 9.1:1 CR (From my measurments and Tomei's the stock head gasket is 1.4mm) A 1.2mm head gasket will raise the CR by 0.1 points.

 

[j10gtr]

But ho the hell would want 7.8:1 CR?? Pointless if you ask me. I challenge you guys to think outside the box and RAISE the compression ratio.

Been there my compression ratio is either 8.5:1 or 8.6:1 and the car drives much better off boost and seems to generate boost much better than the equivelant cars i have been in with the JE pistons @ 7.8:1.

Thanks
Paul

 

[J-GTi-R]

Ok, I was trying to be diplomatic, but what the hell... :roll:

The compression is way too low for my tastes, I agree with Nikko and think a high compression engine (relatively speaking) with low boost (again relatively speaking), good cams and a properly matched turbo will give a muche better and more drivable result.

 

[purplemonster]

i must add my 2p worth here

ask one thing how much CR dose a wrc car run .and guess what its bloody high ,higher then u think ,but limited to 300bhp and 400lb?


now i rather 400lb torque than a high bhp figure and lower torque?

next questions where can i get 1mm over size pistons at a good price ,with out paying stupid UK tuner prices

thanks

 

[Sirnixalot]

Food for thought

The new WRX STi runs a 10:1 CR with 16psi.

THe thing with high compression and boost is tuning. 9.0:1 is a good compromise. Not to mention my turbo will spool 300-500rpm quicker than an 8.3:1 CR motor 8)

Quicker spool, better fuel economy and more torque......or slower spool, horrible fuel economy and less torque. For both setups you have to get the ECU setup. You will be able to run 12psi max on the Optimax with the 9.0:1. Anything past that needs water/methanol injection or race fuel. That is conservative but i dont want anyone to say "well he said i could run 1.6bar on 98Ron and ill be safe". You may be able to get 1bar on the 98ron but your tuner must be good and it may be close to a lean condition.

9.0:1CR pistons tuned to a 12:1 A/F ratio and you are good to go

 

[purplemonster]

anybody know the web address for JE?

im looking for pistons at the moment for my rebuild

ROB

 

[sypher]

sirnix' can u tell me and well who ever reads this how to calculate C/R and or what variables you have thought of eg; the above gaskets pistons and tdc compression bath

 

[Sirnixalot]

i dont know the combustion chamber CC off hand but when im not so sore from the gym i can lay the cylinder head flat an measure.

if you search for compression ratio calculator on google you get a bunch of sites with them.

 

[Anonymous]

So what CR are ND's JE pistons? Do they use the same ones for all their conversions?

Are you taking head gasket thickness taken into account?

 

[Sirnixalot]

ND's pistons (with the standard 1.4mm head gasket) have a CR of 7.8:1.

They dont list pistons in any of their upgrades (that i can see anyway). I bet they might offer a 2mm head gasket on the higher bhp ones along with the super low CR pistons.

 

[sypher]

thanks