4g32 pistons

[krohny]

i just pulled the head off my engine, found 35S / 0.50 on the pistons..
can anyone give me any info on these pistons?

[davetrees]

Given that (according to the Saturn workshop manual) :
- 4G33 pistons have "33" on top,
- 4G32 have "32", and
- 4G32 GS motor have "32S" (with less dish than stock 4G32, for increased compression) ...

.... I would be guessing they are 4G35 GS pistons, 0.50mm oversize

Seeing the motor came out of an ex rally car, there's a good chance it has been bored out .... The 4G35 (1686cc) was the stock motor in the GTO , so it sounds like you have a "1700" on your hands

What's the stroke ? You may even find it's been taken out to 1770, which wasn't uncommon for rally Lancers back in the day ! (and is about as far as you can take a 4G32 block, as I understand it)

[krohny]

the stroke on the 4g35 is the same as the 32, standard bore is 79 vs. the 32 which is 76.9?
but that info is just from a quick internet search..

right.. so i should use those pistons i guess.. ha ha

[krohny]

the stroke on the 4g35 is the same as the 32, standard bore is 79 vs. the 32 which is 76.9?
but that info is just from a quick internet search..

right.. so i should use those pistons i guess.. ha ha
will i have any overheating problems..?

[davetrees]

why would you expect to have overheating problems ??

[krohny]

i have heard if you bore to much they get overheating problems..
the water jackets get too thin or something?

[davetrees]

It was a OK running motor before with those pistons, wasn't it ? As long as the water jacket hasn't been breached there shouldn't be a problem.

It's either that or ditch the block ... you obviously can't put stock pistons back into it !

You should measure the actual stroke while you have it apart .... just because the 4G32 & 4G35 have same stroke ex factory, doesn't mean yours hasn't been changed (ie. different crank put in it). You will need the bore x stroke to get it logbooked anyway (unless it has one already .... what capacity does it say ?).

Looks like we won't be running in the same capacity class once you get it going

[tandanus]

IIRC the 1300 Saturn (short stroke ) had a nitrided crank and that would make it a decent swap for a large bore/short stroke revver
T.

[krohny]

the stroke is 86mm, i think the bore is 79.5..
so the crank is the stock size.. what is the CC limit to stay in your class? (dave)

[davetrees]

Depends upon the event .... but usually 1600cc is one of the class limits HRA events don't use capacity classes.

For a beginner, what class you are in shouldn't be a consideration ... just get it out there in the forest !!

[krohny]

not worried, just wondering.. will be good to race with people i know, and who helped me build the car

[Rally_2.6LC]

Krohny, I was looking at doing all these u beaut mods to my car, suspension, gearbos, brakes and engine. Looking at the extremes of what a motor can do and finding all this power by using different pistons, offset crank to get longer stroke, massive modifications to heads via porting and light weight rockers etc.......but i have recently had an ephiney.
Im only new to the world of rallying and cant drive that well, so there is no point building an awesome motor with high compression, quadthrottle bodies, motec computer, stronger gearbox, upgraded vented slotted rotors and brembo calipers.
Save your money now and just learn how to drive, better to have a slow car doing this as well.

I also recently aquired a 2.2L sigma motor (bored and stroked, its now an almost 'square' motor) and I was going to go 2.2L turbo for a GA project I have. I scraped that idea. I found there is no point engineering something for what it wasnt designed for, so im going high comp 2.2L with twin webers (as it was originally designed) and going to use this in my GC and put an evo motor in my GA.

In a nut shell, dont spend heaps of money building a car, buy one someone else has worked out and researched as its heaps cheaper. Or drive with what you have. Put good brake pads on it and a reliable motor for people starting out. If that motor was build before and still ran well....use it as it was



Cheers Matt

ps not having a stab at you, just giving you my realisation of the world of rallying

[tre04z]

I was told by a motor reconditioner that the 4g32 is the only block that can be taken out 60thou which in real speak is 1.5mm i think. Before you get any thin water jacket walls or any other silly stuff like that. My block has been taken out 40thou which is 1.0mm making it a 1797cc, this coupled with a mild cam grind and twin 40mm webers makes a punchy little thing, but still controlable in most conditions.

Did i mention i love the rain. so much fun with minimal tyre wear.

[krohny]

My 4g32 is bored out 2.6mm already
Bore is 90.5pm

[Mr Aerospace]

Thanks for the tip Matt, but the engine Krohny is talking about (which was inherited from an old rally car we purchased together) is actually a 4G32 bored out to be a 4G35, and I can promise you we had no idea that this had been done.
Unfortunately, when it came to starting the engine again, it ate a few piston rings so we had to pull it apart, and that's when we found out what was going on. (plus the info provided here helped us find suitable rings for it)

For the most part, we were just incredibly lucky when we purchased what looked to be a clapped out old rally car (intending to use its new roll cage only). We had no intention of making an overly powerful engine, but in the end it just turned out that we already had one, so we are trying to do it some justice.
For those who are interested...here's a very small list of what we found:

C2 Cylinder Head
No. 5 Camshaft
4G35 Pistons (79mm +0.5mm oversize)
Baffled Sump (homemade)
Lightened Flywheel
Larger Clutch
Larger Starter Motor
Larger Alternator (with larger pulley to reduce power losses)
Clutch Fan (also larger pulley)
Electronic Dizzy
Twin Mikuni 44PHH sidedraft carbies (thanks davetrees)
Mitsuba Electronic Fuel Pump, etc.

[davetrees]

I've been offered a set of good condition s/hand 80mm forged pistons for a 4G32. Worth about $1200 new apparently .... you could probably get them for $500 ONO.

If anyone is seriously interested, PM me & I can put them in touch with the seller - no tyre kickers please !

(Don't ask me for any details on them, I know nothing about them other than that they were offerred to me).