Forged stroker pistons - recommendations?

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Aussie Charger

Aussie Charger

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I've got a 408 stroker with "slap-happy" forged Diamond flat-top pistons. It's so bad that when I pulled the heads recently, I noticed the bores had scuff marks on them.

The engine is about eight years old, but doesn't have too many miles on it. It doesn't burn oil, and goes quite well (400+rwhp). But part of being an older engine is the fact there weren't a lot of stroker pistons to choose from when it was built back in 2006.

The Diamonds are good, strong, light pistons, but they have short skirts, a lot of clearance when cold, and a fair amount of piston rock. They were clearanced for nitrous (which is obviously part of the problem) but I've never used it and won't be.

So I'm looking to replace the Diamonds with something quieter, made of 4032 instead of 2618 material.

Specifically, I'm looking at a set of Wiseco Pro Tru pistons.

Are they any good?

My main priority is a piston with less sidewall clearance when cold, as the car is driven frequently and only raced a few times a year, so usually runs a bit cooler. I know strokers are prone to piston slap by design, but does anyone have any experience with quieter forged (4032) pistons for small-block Mopars?

Thanks.
 
Aussie Charger said:
I've got a 408 stroker with "slap-happy" forged Diamond flat-top pistons. It's so bad that when I pulled the heads recently, I noticed the bores had scuff marks on them.

The engine is about eight years old, but doesn't have too many miles on it. It doesn't burn oil, and goes quite well (400+rwhp). But part of being an older engine is the fact there weren't a lot of stroker pistons to choose from when it was built back in 2006.

The Diamonds are good, strong, light pistons, but they have short skirts, a lot of clearance when cold, and a fair amount of piston rock. They were clearanced for nitrous (which is obviously part of the problem) but I've never used it and won't be.

So I'm looking to replace the Diamonds with something quieter, made of 4032 instead of 2618 material.

Specifically, I'm looking at a set of Wiseco Pro Tru pistons.

Are they any good?

My main priority is a piston with less sidewall clearance when cold, as the car is driven frequently and only raced a few times a year, so usually runs a bit cooler. I know strokers are prone to piston slap by design, but does anyone have any experience with quieter forged (4032) pistons for small-block Mopars?

Thanks.
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I had a lot of piston slap on a second hemi I bought way back when I couldn`t afford a lot of engine changes, took them out and knurled them hard, worked like a charm, took the slap out-carried a little oil in the knurl, no problem. only gasket money spent.
 
I'm not in a position to knurl pistons myself. And if I pay someone else to do it, I might as well buy new pistons and sell my old Diamonds.

Maybe the simpler question is: if you've built a stroker, what pistons did you use, were they noisy and are you happy with them?
 
We went with forged Icon pistons for my stroker build, but only because that is what was included in the Scat kit. Wiseco makes a good piston. Back in the day, they were the go to piston for racing motorcycles.
 
BrianT said:
We went with forged Icon pistons for my stroker build, but only because that is what was included in the Scat kit. Wiseco makes a good piston. Back in the day, they were the go to piston for racing motorcycles.
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Great choice.... Sweetheart's. Mike 'em ,all I can ask....
 
My 390 has Ross pistons, 50,000 miles of WOT and they don't make noise. Sounds like yours were too loose to start with. It would have to be real bad to scuff tho. What temp thermostat do you run.
 
I was going to recommend Ross too. Almost sounds like you need to bore the next size up to get that right. Good luck.
 
I've used Ross, SRP, Diamond, and Icon. With the right bore clearance they are all quiet. They als all have short skirts to clear the crank counterweights and all over time and use will leave marks on the cylinder wall - especially the lower 3rd of the bore and on the major thrust side. That's where the skirts are during the hardest "push". I'd suggest you verify the bores are perfect (via measuring), have the block sonic tested to determine the strength of the walls, and then determine if new pistons can be used or not. That will depend on the existing bores and the recommended wal clearance of the different manufacturers. You may find there are no usable pistons for the wear without going bigger.
 
why not hypers or cast? your not racing regularly, maybe they would be a quieter option.
 
moper said:
I've used Ross, SRP, Diamond, and Icon. With the right bore clearance they are all quiet. They als all have short skirts to clear the crank counterweights and all over time and use will leave marks on the cylinder wall - especially the lower 3rd of the bore and on the major thrust side. That's where the skirts are during the hardest "push". I'd suggest you verify the bores are perfect (via measuring), have the block sonic tested to determine the strength of the walls, and then determine if new pistons can be used or not. That will depend on the existing bores and the recommended wal clearance of the different manufacturers. You may find there are no usable pistons for the wear without going bigger.
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Yes, you've described exactly what's happening.

I'm expecting to go bigger bore. As mentioned, the pistons were originally clearanced for NOS, which I decided not to use (I'm already in the 11-second bracket and want to stay there).

The engine has a 180F thermostat and does get up to operating temp on the road, but takes a while to get there and a little time to warm up. But even when it's warm, it slaps (due to the extra clearance).

I basically want a more "street-friendly" piston. As far as I know, no-one makes flat-top hypers for Mopar strokers, so 4032 forged would be the next best material as far as I'm aware.

I have an early casting 360 block, so I should be able to go 4.04 easily - possibly 4.06 or 4.07 (currently +0.030). The block will be getting sonic tested first to make sure, but I also have access to another early 360 block if mine isn't suitable.

That said, I'm inclined to go for +.040" or +.060" flat-top piston. I could go dish, but I'd lose about 1 point of compression - from 11.4 to around 10.4 - so that's not an ideal option at this stage, especially with alloy heads and a decent roller cam.

Thanks for the suggestions so far - I'm happy to hear more!
 
Personally I don't support the use of hypers on the 4" engines. The piston speeds these engines can develop at 5K are right on the hairy edge of safe for hyper materials. I'd rather not use them there. I'm not down on them - I run them a lot in other stuff but there's a reason better piston materials exist and piston speed and dealing with it is a bog one.
I've had Ross and they are not my favorite. I'd put them on par with Icon. Not "bad", good value, but not my first or second choice. I like SRP and then Diamond. Diamond is more money which is why I place them second. SRP makes a really nice quench dish that's only 17ccs. That might be a good compromise for you but they don't offer a flat top. I'd go Diamond for the flat top.
 
I have Diamonds in my stoker, but I have not experienced the issues you are having. My last motor had JE pistons, also very nice and light.
 
Well I think you were asking for opinions on Wiseco Pistons and that is what I have in my 412, they so far are working fine and I do not hear any piston slap, I bought a eagle stroker kit from Indy Cylinder Head and that is what they had in their kit for pistons, I know Indy doesn't have a good name on here, but I (luckily) didn't have any issues with them. I also have Plasma rings not sure if that makes any difference or not, but I say give them a shot!!
 
The Wisecos come with plasma rings in the kit, don't they? Do you have the Pro Tru pistons in yours or another type? Do they have the friction coating on them?

They look like they could fit the bill and seem reasonably priced - which is why I asked about them.

I won't rag on the Diamonds, as I don't believe they are at fault: one thing I did notice when I pulled the heads is that one of the pistons had clear signs of detonation, while the heads showed no signs - and neither did any of the other seven pistons. While the chambers were not all even in volume (ranging from 61-63cc), the "dodgy" piston did not have an especially small chamber. I've since CCed all the chambers myself to 64cc.

Unfortunately, I had this engine built some time ago when I'd just arrived back in Australia and had no tools and nowhere to work on an engine, so I paid someone to do it and I've come to believe he may have used a second-hand set of pistons (which is why 7 out of 8 looked almost new when I pulled the heads, but one looked fairly beat-up).

I've done a lot of work to the car and engine since, and this will be the final rebuild for the foreseeable future. Apart from the machining, I'll be doing the work myself this time and simply want to do it right.

My #1 priority is streetability: I want a car I can jump in and drive anywhere on weekdays, and pull 11s all day on weekends when I go racing. That's the reason I went with the stroker and hydraulic roller cam in the first place. I'm really hoping the guy who built the engine didn't cut any more corners, but I guess I'll find out when I pull the bottom end apart . . .

Again, I appreciate all the info you guys are sharing. There are some good Mopar resources in Australia, but obviously they are not as popular here as Chevs and Fords, and nowhere near as popular as they are in the US. Cheers.
 
I had hyper pistons once. Got 7 good ones, look like new, 3.94 bore. Now I have a sleeve and ross. My ross were custom order. Hard to get a 318 bore piston, 9.5-1, for 302 heads. Lol. Wiseco has always made great pistons.
 
I had Diamonds in my 416 and a couple of the skirts didn't look too great when they were pulled. They could have been re-used, but the bores ended up torque plate honed to 4.075 to clean them (would have been sloppy) so I had a custom set of JE's ordered with a reverse dome (not dish) to get the compression I wanted. They looked to be really nice and stout pistons and were just a touch heavier than the Diamonds I believe. I want to say they came in at 500 grams or just under. Something like that. Motor should be done in a couple weeks so I'll ask my builder how he liked the fit of the JE's.
 
"The Wisecos come with plasma rings in the kit, don't they?"

Mine did but I wasn't sure if Indy did that or they were that way from Wiseco.

"Do you have the Pro Tru pistons in yours or another type? Do they have the friction coating on them?"

Pro Tru and nope mine were not coated.
 
Yeah yeah. We all know what Aussie Chargers look like and we all want one. Rub it in why don't you? lol
 
Mahle forged pistons , 10,000 miles and still going strong . Make a bit of noise on starting , quiet as soon as it gets warm .
Where can I get an Australian Charger ! I want one !!
 
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