pistons on stock ecu

aus jd 2703

New member
ok i am thinking bout running my stock ecu with some cp 9:1 forged pistons and a fmic, is this possible or will the ecu's mapping be to far out for te new compression ratio?
if it matters its an Australian delivered gt four ecu (non rc)
 

Gary ST165

New member
i think it will run OK :) >>> well put it this way... i'm running approx 9.0:1 CR on stock 185 RC pistons and RC ECU, due to fitting a 1.0mm MHG and having the cylinder head skimmed 0.08mm.

FYI, if the ecu detects knock it will revert to a safer look up table.


how long do you plan to run the stock ecu?
>>> because it will continue to bore wash
...and you will never make the most of the forged pistons...ie generate the heat required @ 350 > 400 bhp to take in to account the extra clearances for the high expansion pistons. piston slap + over fuelling will result in a very short engine lifespan.
 

vip09

New member
It will work perfectly find. I ran 9.0:1 pistons with a TD06-20G turbo on stock ecu and fuel sytem. It ran GOOD! :)
 

aus jd 2703

New member
trying to use my own threads,
has any one had good or bad luck with brands of pistons?
im looking for 20 though over 9:1cr
so my main options are:
ross
arias
CP
i hear good things bout cp but nothing about the other?
opinions please?
 

BriinumsBo

New member
anybody got old 86.5mm pistons for sale? oem or forged, doesnt matter, dont want to buy fresh as probably someone has them lying around..
 

Mafix

New member
from mr2oc.com rsrace
Ok so Ive gotten several questions and concerns about pistons and compression ratios with the 3sgte pistons on the market and I wanted to make a post to clarify everything.

CP, JE, and SRP all have 9.0:1 pistons. Its the only compression ratio they offer, and I often get customers who just prefer 8.5:1.

Arias and Ross both list a 8.5:1 piston but heres the part to pay attention to.

CP/JE/SRP all list their compression ratios assuming an aftermarket .040" (1mm) thickness headgasket.

Ross/Arias both list their compression ratios assuming a factory .056" (1.4224mm) thick headgasket.

Well, if you measure the compression ratio with the CP/JE/SRP pistons using a factory headgasket thickness like Ross/Arias do, you get an 8.5:1 piston, and likewise, if you measure the compression ratio with a Ross/Arias piston using a 1mm aftermarket headgasket thickness, you get a 9.0:1 piston.

So, all of these pistons are the same compression ratio, just listed in different ways. I got with my guy at JE and we used their high tech fancy shmancy inhouse software to get the compression ratios using different thickness headgaskets and this is what we came up with...

Here are the headgaskets we worked with that are available for the 3sgte:

TRD: 0.8mm
Cometic: 1mm
HKS: 1mm & 1.6mm
Apexi: 1.1mm & 1.5mm & 1.8mm & 2.1mm

(CP/JE/SRP/Ross/Arias Pistons)+(TRD 0.8mm Headgasket)=(9.2:1)
(CP/JE/SRP/Ross/Arias Pistons)+(Cometic/HKS 1mm Headgasket)=(9.0:1)
(CP/JE/SRP/Ross/Arias Pistons)+(Apexi 1.1mm Headgasket)=(8.8:1)
(CP/JE/SRP/Ross/Arias Pistons)+(Factory 1.4224mm or Apexi 1.5mm or HKS 1.6mm Headgasket)=(~8.5:1)
(CP/JE/SRP/Ross/Arias Pistons)+(Apexi 1.8mm Headgasket)=(8.375:1)
(CP/JE/SRP/Ross/Arias Pistons)+(Apexi 2.1mm Headgasket)=(8.1:1)


Wiseco's 9.0:1 piston however is 9.0:1 with a factory .056" (1.4224mm) headgasket, so it truely is a 9.0:1 at the same headgasket thickness where the rest of them are 8.5:1

If you want to get close to an 8.5:1 compression ratio with a Wiseco Piston you will need to use the Apexi 1.8mm Headgasket. That combo will put you right around 8.6:1 compression. or you can use the Apexi 2.1mm headgasket to get to 8.4:1 ... more clearly illustrated below:

(Wiseco Pistons)+(TRD .8mm Headgasket)=(9.4:1)
(Wiseco Pistons)+(Cometic/HKS 1mm Headgasket)=(9.2:1)
(Wiseco Pistons)+(Apexi 1.1mm Headgasket)=(9.1:1)
(Wiseco Pistons)+(Factory 1.4224mm or Apexi 1.5mm or HKS 1.6mm Headgasket)=(~9.0:1)
note: i put the "~" because all of my calculations come up saying the wiseco piston is 8.8:1 with a factory headgasket thickness, but they advertise 9.0:1 so its about 9.0:1
(Wiseco Pistons)+(Apexi 1.8mm Headgasket)=(8.6:1)
(Wiseco Pistons)+(Apexi 2.1mm Headgasket)=(8.4:1)





disclaimer: this is slightly simplified, in order for it to be exact, you would have to do this for every bore size as well and go out a couple more decimal places on the compression ratio but for the purpose us car guys are using it for, this is as accurate as we need.
__________________________________________________ _______________
Now for the sake of saving time and making things easier for you guys, I will go ahead and list the part numbers for everything ive talked about in this post.

Cometic 1mm 87mm Headgasket: C4314-040
HKS 1mm 87.5mm Headgasket: 2301-RT034
HKS 1.6mm 87.5mm Headgasket: 2301-RT035
Apexi 1.1mm 88mm Headgasket: 814-T201
Apexi 1.5mm 88mm Headgasket: 814-T202
Apexi 1.8mm 88mm Headgasket: 814-T203
Apexi 2.1mm 88mm Headgasket: 814-T204

Wiseco Pistons:
K615M86 // 3sgte // Bore: 86.00mm (Standard Bore)
K615M865 // 3sgte // Bore: 86.50mm (+.020" Overbore)
K615M87 // 3sgte // Bore: 87.00mm (+.040" Overbore)

CP Pistons:
252061 // 3SGTE // Bore: 86.50mm (.020" 0.5mm overbore)
252062 // 3SGTE // Bore: 87.00mm (.040" 1.0mm overbore)

JE Pistons:
SC7449 // 3SGTE // Bore: 86.00mm (Standard Bore)
SC7450 // 3SGTE // Bore: 86.50mm (+.020" Overbore)
SC7453 // 3SGTE // Bore: 87.00mm (+.040" Overbore)

SRP Professional Pistons:
283458 // 3SGTE // Bore: 86.00mm (Standard Bore)
282309 // 3SGTE // Bore: 86.50mm (+.020" Overbore)

Arias Pistons:
3710101 // 3SGTE // Bore: 87.00mm (+1mm [+0.040"] Overbore)

Since this isnt a "for sale" post Im not going to post any prices that would clutter this up, but if you are interested in purchasing any of these items, or just wondering how much they cost, please check out our sale post in the vendor section here: http://www.mr2oc.com/showthread.php...065#post4017065

--------------------------------------------------------------------------------
Last edited by RSRACEcom : September 29th, 2009 at 08:13.
 

BriinumsBo

New member
thanks Mafix, I owe you a pack of beer! :D this should be written in alltrac.net tuning section, as it should cross everyone`s mind who wants to swap pistons and looks over the engine section on frontpage..

p.s. the link doesnt work..
 

aus jd 2703

New member
Now I'm slightly worried about running my wiesco's lol they really are high compression. I'm aim ing for 9:1 with normal gasket thickness and a slightly decked head and block.
 

BriinumsBo

New member
does the wiseco CR make a difference? how would it impact tuning? im using sw20 metal gasket (same as cometic). i`m about to buy wisecos, but still considering..
 

gt4tified

New member
aus jd 2703":2a7h5k6e said:
trying to use my own threads,
has any one had good or bad luck with brands of pistons?
im looking for 20 though over 9:1cr
so my main options are:
ross
arias
CP
i hear good things bout cp but nothing about the other?
opinions please?

While I have heard of CP pistons going bye-bye, never heard the same yet about Ross or Arias.
 

BriinumsBo

New member
gt4tified":24chmtcm said:
While I have heard of CP pistons going bye-bye, never heard the same yet about Ross or Arias.
You shouldnt write comments like this because they make impact on decision. CP are good pistons. ALL forged pistons have failed in various engines. Not because of their construction but because something else went wrong. Bad bore finish, no honing, wrong clearances, detonation, wrong oil, no warmups, ring end-gap misalignment, etc.. all can lead to piston failure! And in many cases the owner blames the brand of pistons. Even stock cast pistons have been proven to work safely over 400whp, if the tuning is good.
My suggestion - do your research on piston extra features - weight, design, coatings applied from factory, corner rounding, friction grooves, dome squish CR, thermal expansion, etc. There are lots of features and most race teams do some extra piston finishing&coating that costs even more than the pistons. When you`ve chosen your brand, do extensive research on best clearances (manufacturer specifications may not suit all engines perfectly) and do as much as you can to install pistons perfectly.
There are pros & cons and in the end I wouldn't put forged pistons on a stock engine, but price difference made me choose forged Wisecos as Toyota cast oversize replacements cost a zillion here.. If there was no price difference, i`d choose oem cast for <300whp engine. Much tighter clearances, less oil consumption, less engine wear, no ugly piston slap, less damage when pushing cold engine.
my 2c :D
 
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