Z32 turbo pistons in SR20DET

[timtiminy]

hey guys i was looking around and found that some FWD SR guys are putting Z32 300zx turbo pistons in there DE motors as a cheap alternative to expensive forged overbore low compression pistons. The info i have on them so far is that they are 87mm and 8.5:1 compression ratio and fit the oem rods. I have yet to hear of anyone using these in their rwd SR20DET, I may try it as i have to bore out my block and need to save money somewhere. Plus I wont be going over 350hp so I think these will be a good option. If anyone has any info on this or has done it before, please post. I am really interested in this option rather than spending $500 on forged pistons.

[GSXRJJordan]

... Plus I wont be going over 350hp so I think these will be a good option.

Earth to tim... EARTH TO TIM!

You don't need aftermarket pistons for 350hp... just a good metal head gasket, a bigger turbo, and the associated fuel mods.

BTW, stock SR pistons arent bad. I would imagine the only advantage to the VG pistons would be 1mm overbore, but I'm not all that comfortable boring the already-thin-walled SR anyhow.

[timtiminy]

only reason why i am even considering this option is because i have to overbore.... otherwise i would use oem sr pistons..

[TheWolf]

you can buy forged mahle SR pistons for $350 with rings... how much cheaper are the z32's...

[Ali 556]

Or You Can Get Some 2JZ-GTE Pistons...they Are 86mm And 86.5 And 87....If they Fit On The SR Rods ( I don't Think So)

And On Supra's They Made Up To 1017Whp On STOCK Engine Then the rod bolt's gave up....

:hs:

Ali

[trsilvias13]

isn't the stock sr20det 8.5:1 compress stock?

[GSXRJJordan]

isn't the stock sr20det 8.5:1 compress stock?

Around there, yes.... but read his earlier post:

only reason why i am even considering this option is because i have to overbore.... otherwise i would use oem sr pistons..

Interesting. So you've got scoring and must overbore? I'd say it's a decent plan... I'm guessing a set of 4 Z32 pistons is less than $100?

[timtiminy]

about that brand new... looking at getting some used ones for free though...

[fliprayzin240sx]

about that brand new... looking at getting some used ones for free though...

Why the fuck would you wanna use some used one. You already found a cheap alternate, atleast slap some new ones in there....

[timtiminy]

new ones won't be any different than used ones if there is hardly any wear on the used ones and i would put new rings on them. its not like pistons wear out or get weaker over time...

[TheWolf]

new ones won't be any different than used ones if there is hardly any wear on the used ones and i would put new rings on them. its not like pistons wear out or get weaker over time...

this is why 240's will become the new dsm...

[Def]

new ones won't be any different than used ones if there is hardly any wear on the used ones and i would put new rings on them. its not like pistons wear out or get weaker over time...

Actually they do. It's called metal fatigue, and aluminum constantly fatigues and never reaches and infinite fatigue strength like steel.

Whether it will fail as a result, I doubt it. But to save $100 and risk the PITA of replacing pistons or scrapping a block - why would you even think about tossing in used OEM pistons?

[fliprayzin240sx]

Personally, use the Z32 pistons and get better rods/bearings instead of the stockers. Im not a big fan of OEM rods...

[timtiminy]

i have heard that Sr Rods are actually a strong point to the motor... Check this out... 4G63 Turbo Rebuild with VG30DETT Pistons 87mm - Zerotohundred.com - The Automotive Lifestyle Network (http://www.zerotohundred.com/newforums/engine-and-performance/168951-4g63-turbo-rebuild-with-vg30dett-pistons-87mm.html) I guess they rebuilt a 4G63 with the VG30DETT pistons and are pushing 600hp.. oh and thats with used VG turbo pistons and stock rods.

[timtiminy]

Alright so i sourced a set of low mileage used VG30DETT pistons, Dirt cheap and in great condition. I also found a guy who has a SR torque plate that is willing to let me use it to get my block overbored the 1mm needed. Machining cost are going to be the most expensive thing but i think after everthing is said and done I will have saved hundreds of dollars from going aftermarket pistons and only have spent a little bit more than if i would've had a good block to have started out with and was just doing a OEM rebuild. So basically I will have an 1mm overbore OEM rebuild when everything is said and done.

[Teambadrun]

Just make sure the pin height , and amount of CC in the dish...

you need around -12cc of dish on a stock SR or there abouts...


VG pistons in a SR sounds good if its that cheap thou.. go for it

[timtiminy]

Its been done before i know that alot of fwd na SR guys use the na VG pistons to bump compression up. The VG turbo pistons are even more stout then the SR turbo pistons too. I will take pictures of everything as the process goes along.

[alexander500]

looking at getting some used ones for free though...

Hold it, hold it, hold it

This sounded like a good idea until it shit all over itself right here.

I genuinely hope this works out, but I can tell you from experience that it is cheaper to do it right.

[MadScientist]

HKS Driver (NOB) Nobuteru Taniguchi uses Z32 pistons in his S14 SR20.

I have been thinking of this and keeping it on the DL... This is one of those rare things you hear little about.

-Drew

[GSXRJJordan]

HKS Driver (NOB) Nobuteru Taniguchi uses Z32 pistons in his S14 SR20.

I have been thinking of this and keeping it on the DL... This is one of those rare things you hear little about.

-Drew

I didn't know that! Wow. Does that mean he's running HKS forged Z32 pistons, or OEM? Moarrr infoooooz pllzzzzzz.

[MadScientist]

He is using stock Z32 pistons... not the HKS.

He also suggest that the Z32 pistons creates a 2.1 option... if you look at the pistons (SR vs Z32) the Z has a shorter profile.

This is a Z32 Piston from Wiseco (88mm)
http://www.euroexportinc.com/images/K549M88_02.JPG

This is a SR20DET Piston from Tomei (87mm)
http://www.frsport.com/images/detailed_images/Tomei_1131870211_511997479094782b3458cc76.jpg

-Drew

[slider2828]

How does this affect tuning and the overall performance? This is interesting....

[timtiminy]

Alexander500: I dont see why its such a bad idea to reuse used pistons? plenty of rebuilds are done reusing original oem pistons. I will be using new rings. The pistons dont necessarily wear out...The only thing to worry about is metal fatigue. aluminum constantly fatigues and never reaches and infinite fatigue strength like steel.
Whether it will fail as a result, I doubt it.

[timtiminy]

MadScientist: Please tell us more about this, I am quite interested.

[s13envy]

Alexander500: I dont see why its such a bad idea to reuse used pistons? plenty of rebuilds are done reusing original oem pistons. I will be using new rings. The pistons dont necessarily wear out...The only thing to worry about is metal fatigue.

i think what everyone is getting at is why would you not replace something critical to your motor like pistons, especially when they are so cheap to replace???? to me its a no brainer whether or not to replace the pistons in this situation.

[!Zar!]

I never have heard anything about this before.

[timtiminy]

I dont see it as such a big deal as most people are making it out to be to use new pistons rather than good condition used ones. I think that if i agreed that it was such an important thing to use new ones then i would also want to get new rods, which see about the same abuse as pistons do in my mind. I have yet to get pistons so my mind isn't completely made up in whether or not i am going to get new pistons or just use used ones.

[slider2828]

I have actually heard this in other cars. Like 2zz motors used like honda pistons or something like that.... I think the esprit's mrs does that....

[timtiminy]

yeah i have heard of D series honda motors using suzuki grand vitara pistons which lower compression and are stronger, they use them when the turbo the D series motors and have been able to get like 400hp with no problems. Thats what got me looking into alternative pistons for the SR motor, especially since i have to overbore my block and didnt want to spend and arm an a leg on forged slugs since im not planning on making huge power.

[slider2828]

z32's would rock... Try it! But I would spend a little more and sleeve it though.... Just for piece of mind.

[gottdeskrieges]

Sounds good and all. But, on the 4g63 I 've seen over 600awhp on stock bottom end. I was on low 400's with my setup. Always intresting to see people doing something different and finding another alternative. Makes it easier for when you cant find something just get it from another car and work with that haha. Good Luck bro and hope everything works out for ya.

[timtiminy]

If i were going to sleeve the block i would just do an entire bulletproof build with forged rods and pistons, the objective here is to do this as cost effective as possible.

[MadScientist]

I am not the God of Z32 pistons... I have just been looking into doing this for a long time and I rarely hear any real info about it.

I will be doing this soon... The only thing I am worried about right now is selling my PE headgasket (87mm) and getting a new PE (88mm) one.

Z32 stock Pistons are 87mm... most aftermarket ones only start at 87.5mm... this is my logical choice of size anyway because finding a 89mm headgasket is just impossable... or not something I trust to use.

If your going to do piston swap on the SR20 the RNN15 GTiR pistons are great and cheep... if your planning to build it, go forged... If you planning to Bore, but keep your stock crank , go with Z32 87mm pistons.
The only real issue is finding them in sets of 4.

The local Machine shop that is highly trusted by many engine builders in this area... Said he doesn't want to sleeve the SR because its aluminum and he would have to re-align the mains... I dont think going over 1mm is going to be that bad on a stock wall, but that is my limit!

-Drew

[slider2828]

I have forged from JE and they have a 86mm bore for sr's

[timtiminy]

okay so is it recommended to go .5mm bigger on your head gasket when you overbore? Like if i did the stock Z32 pistons at 87mm should i go with a 87mm head gasket or a 87.5mm?

[MadScientist]

^^^ Correct

This is from Power Enterprise website.
How to select right size of gasket:
Standard of Gasket bore vs. piston size
Piston OD + 1.0mm to 2.0mm. The most of car manufacture design the gasket size to be 1.5mm to 2.0mm larger than the piston OD
Caution:
Do not overlap the tip of gasket and champher area
(See the picture)
http://www.powerenterpriseusa.net/products/engine/gasket/images/gasket%20bore-piston.jpg

Compression Ratio Changes by the thickness:
Example: 86mm stroke engine with 9:1 compression ratio can be reduced to 8.6:1 by adding the head gasket thickness, approx. 0.56mm.

http://www.powerenterpriseusa.net/products/engine/gasket/images/SR20det.jpg
Use 87mm Gasket for 86mm piston and 88mm for 87mm piston.

http://www.powerenterpriseusa.net/products/engine/gasket/images/SR20det-ve.jpg
Major Distributor for the 91mm gasket: MAZWORXl 407-281-1223 (Mark)

-Drew

[timtiminy]

Thanks for that info. wasnt sure about that, i figured it worked that way. Are there certain gasket manufactures that list their sized based on the cylinder bore? for instance their actual gasket diameter is 87mm but is listed as 86mm?

[MadScientist]

I prefer Power Enterprise because they are the best... look at thier site... their HG is like no other... I have a 87mm one and I ordered a rebuild kit... the stock HG is so nasty compaired to PE... I have seen Tomei/HKS/etc... they are good but... PE is god sauce... holds 1400hp and something retarded on boost presure.

MSRP is $230... call Kure.

-Drew

[s13envy]

I believe mazworx recommends Apexi HG's. Said they'd hold something like 60lbs of boost or so....Just over $200

[timtiminy]

Ive noticed some gasket manufactures make a 86mm gasket for the sr20det so thats why i was wondering if it is just listed as 86mm for the bore of the motor but the actual diameter of the gasket is 87mm. Anyhow i have heard that Power Enterprise Gaskets are one of the best and Apexi uses a similar design so they are comparable. Another gasket i am considering is cosworth. I have heard mixed reviews on cometic so not too sure about that, I have heard that if your block and head are freshly decked you wont have any problems but even though i will have a fresh surface on both the block and head i dont want to have to tear the motor apart again just to change the HG and have to spend money a second time.

[MadScientist]

OK , so I need a Torque Plate... what is the deal with finding one.

-Drew

[timtiminy]

High Performance Engine Builder Tooling and Harmonic Dampers: BHJ Products, +1 (510)797-6780 (http://www.bhjproducts.com/) <-- They sell a torque plate for the sr20

[MadScientist]

They sell for the SR20DE... its close to a S13 SR20DET but its far far away from a S14 SR20.

-Drew

[timtiminy]

I knew that the S13 SR and SER SR have the same head bolt pattern but I wasnt sure about the S14... They could possibly make you a custom one. Seems like they are capable. if not have emachineshop.com make you one.

[Hashiriya415]

I can bore and hone your block, PM me

[timtiminy]

Hashiriya415: Do you use a torque plate when you bore?

[SleeperTT]

Hey I was wandering some things... I had a built vg30dett. in my Z. well it took a dump and now I'm looking at a s13 to play with. The plan is a S15 Black top. Well I just want that cause of the 6 speed tranny but any ways. I have 6 cp pistons .002 over stock bore..out of my TT motor. I'm intrigued in this conversation cause i already have three eagle rods and the cp pistons. Are the rods the same, and the .002 over stock pistons, would that be a problem with boring the stock sr block to fit the pistons. I'm not familiar with the limits as far as bore for the SR.

[TheRealNighthog]

The problems with the VG pistons are two things. Number one, they are heavy, much heavier than the stock SR pistons by quite a bit, its obvious that these would not be well suited for high rev applications as they would put a lot of stress on the wrist pins. Secondly they use thick rings which does not help out with high RPM sealing. The pistons I am running were designed to use the thin low tension rings from the 2001-2002 Sentra SE. These are much better for high RPM sealing as I am planning to turn 9.5K with my build.

[MadScientist]

Stock v:s Stock - yes the Z32 piston is heavier.

Aftermarket - weight is not an issue. rings are better.

IMO... I wouldn't put stock pistons in anything I have went through the trouble of Boring/ Building.

SleeperTT -The pistons will work but you will neet to bore the SR... you dont need a S15 engine... buy an S14 SR20 and the S15 Tranny, Actually you have a VG tranny... get a Maxiworx kit. The Rods, I doubt will fit the crank, or have the correct length.

-Drew

[timtiminy]

IMO... I wouldn't put stock pistons in anything I have went through the trouble of Boring/ Building.

This is kind of what I am struggling with, since I am overboring I am spending quite a bit of money just on machining costs and would like to save as much money as I can, which is where the idea to use the Z32 pistons came into play. I would like to know the actual weight difference between stock SR pistons and stock VG pistons. I would imagine since the VG piston is 1mm larger in diameter even if nothing else was different it would make a small difference in weight. I would just like to know if it is of any significance. The ring sealing issue that was brought up seems like a bigger issue than the weight, but when I was reading about the SR build with VG pistons in Sportcompactcar they did not mention any adverse effects in this area.

[MadScientist]

SR20DET
Stock
Bore: 3.386, 86mm
Stroke: 3.386
Rod Length: 5.366
Head cc: 46.5
Gasket: .036
Deck: .000

ARIAS Pistons
Bore - 3.406 / 86.5mm
Comp. - 1.260
Dome - (-15)
Compression RatioComp. - 8.5
Gram - 334

VG30DETT
Stock
Bore: 3.425, 87mm
Stroke: 3.270
Rod Length: 6.071
Head cc: 49.5
Gasket: .040
Deck: .000

ARIAS Pistons
Bore - 3.445 / 87.50
Comp. - 1.255
Dome - (-6)
Compression RatioComp. - 9.1
Gram - 360

More tech info to feed on!!

-Drew

[timtiminy]

talked to a guy that did this, seems to be like he had good luck and made over 500whp

[timtiminy]

I have heard that boring without a torque plate is and isnt a good idea... im thinking it would be better with the torque plate, but i cant find anyone in socal that bores with a torque plate for the SR20, JWT used to but they no longer offer machining services, anyone know of anyone else?

[GSXRJJordan]

I have heard that boring without a torque plate is and isnt a good idea... im thinking it would be better with the torque plate, but i cant find anyone in socal that bores with a torque plate for the SR20, JWT used to but they no longer offer machining services, anyone know of anyone else?


Overall, it's probably not THAT big a deal for an SR... but obviously if you had a choice, you would go with the torque plate over nothing.

There's still a few shops that have a torque plate for the SR20 - of course, I see the threads in passing, and never bookmark shit, because I've never needed it done. The thread I'm thinking of had a link to a torque plate manufacturer, and it listed all the motors that used the same plate - there were a few that used the same plate.

I'd start with known SR20 builders, like Garagewerks in Palmdale, and then ask some of the more serious shops (Boso, SP Eng, etc) who they use, and get referrals to machine shops - eventually you'll find one that's got a torque plate for an SR!

[timtiminy]

yeah... I am just wondering the long term effects if i dont use a torque plate to bore.