Okay then. Now I can sleep a little better at night

 

When you saw the 4032 piston that failed, what was wrong with it. Did it have cracks or melting damage?

Kurt

 

Cracks which leads me to believe its a strength issue more than tuning gone bad. I will have to search for it again on Google, but it wasn't on a LSx based engine. It was on an EVO engine.

 

guys how come it takes a 20+ -cc to have a compression lower then 9.0?a sponsor told me that with a dish piston with -9cc will give the compression in my sig with 71 cc heads

 

It depends on the displacment. The larger the displacment the larger the dish cc size to maintain the same compression. For example on a 370 shortblock a 15 cc dish with 72 cc heads will put u around 9.0:1 while it takes 20cc to do the same on a 402 shortblock.

 

370 with -14.9 pistons and 72 cc head will put you at 9.2

 

I said around 9.0 because there are other small factors such as gasket thickness and deck volume which could change the compression ratio slightly.

 

well i will be biulding a stock 346 displacement motor so it will be true wat it states in my sig with a -9cc?

 

yes, i had that combo...diamond -8.6cc pistons..72 cc heads for 8.79:1

 

Yup it will put u around that compresison.

 

awesome thanks guys

 

mahle boost pistons are what i had..never had a problem with em

 

While I concede to Kurt's eminent expertise, piston scuffing is easily controlled by proper piston-to-cylinder clearance. The down-side is a little extra noise on cold start. Coatings help! If your build is designed for maximum strength, there is no choice: Weisco or Diamond, both of which I have run boosted (25PSI), sprayed (250 shot) and N/A (10.30 @131 in the early 90's).

If you're looking for a medium performance build, Mahle makes a good alternative, though they are only advertised as a "Sportsman" piston. JE is a great BBC piston, but the rest of the blanks are machined, not cast, as a Brand F and C piston.

Diamonds are what I have found live. I've reused them in very high HP apps.

My respects to Kurt... Birdie says "HI"...

SC-

 

I'm looking to run about 15PSI on my 370 with up to a 100 shot on top of it. I got diamonds.

 

Im kind of curious as to how many of you guys drive your cars with the forged setup on the street...

How many miles you guys have accumulated on your setup??

 

Hey there, I thought I'd throw this out.... if someone wants a Wiseco in 4032...that's not a problem...just do it as a custom. NOT a big deal. The added expense is nominal especially when you consider the bore, height, and Compression ratio is exactly what YOU want. Zylan skirt coatings, heat barriers, different ring packs, and Tool Steel pins are all options.

Simply put, Wiseco prefers 2618 for our stocking parts because they don't break as easily. I think the other U.S. piston companies would agree...One post of an exploded/cracked/shrapneled (insert brand here) piston on LS1 tech means your name is dirt. 2618 lessens that possibility. If customs are done, the engine builder takes the responsibility for alloy choice.

As for 2618 pistons needing to be replaced all the time, I have yet to get a call from a LS1 customer that needed replacement pistons because they simply "wear out". They'll last longer than the bore and many people have re-used Wiseco pistons in multiple blocks. The pics I'm posting are of an ANCIENT set of our k061a3 strutted pistons from Finish Line racing school. We got them back a month ago and I got the whole set. We've updated the forging since then, but judging by the fact the inside of the forging isn't etched and the skirts aren't even diamond turned, they are from the early 90's. They've been through 5 blocks and have 130K laps on them...no exaggeration. If you figure students run 5 laps at a time on a 1/2 mile track, that's 26,000 times that someone has gotten in and out of the racecar. I don't know what that relates to in start ups, but these had 65k RACE miles on them. The school's owner COULD and WOULD have reused the pistons again, but he sent them to us as a present because he's so happy with them.

As you can see, the skirts look nice and the pin bores are beautiful. The strutted 2618 k061's are designed to be run at .0055" clearance. These skirts now measure 4.024 which means they wore .001". Our LS1 pistons at .004" with a more forgiving forging design, so they don't take the same beating at start up as the k061's do. This is not an anomaly either, Petty Driving school reports 45K miles on the sets we've done for them before they're retired.

When we offset the wristpins, the pistons are quiet. When we dial the cam and taper of the skirt in properly, the contact pattern is widened and the unit loading of the skirt is lessened and they last a long time. When we use a dedicated forging, the weight is low and more than offsets the 3% weight difference of our competitions 4032 forgings..Our 4.125 bore size BIG -32cc dish 427 piston weighs in at 430g...That's light considering the regularity of 800-1000whp engines these days that these pistons operate in. For comparison (on a 1.115 compression height piston), our standard ring lands are .260" top, .170" 2nd, and .080" third. Lands can be made thicker as customs if a different ring pack is used.

Hope this helps your decision making.

-Brian Nutter-Wiseco Piston

 

Wiseco's are what's going in my LS2-I still cannot believe this thread has been going this long trying to dsecide between a 4032 or a 2618 forging-I don't understand Mahles logic-maybe factory repalcement or equivalant is a better choice of words.

 

53,000 on my boosted 6.0 with Mahle 4032 pistons. Still leaks down perfect.

Kurt

 

Awesome responses...

I guess its just a matter or preference for which alloy..2618 just being stronger of the 2

 

2618 is much better suited to taking a beating, it is not stronger. The ring lands in a performance engine will last longer with the 4032 material in our testing. The 2618 material is our choice for high hp builds (over 1000hp we will not give you a choice). The 4032 is our choice for high durability medium hp builds as it will hold "new" power/ring seal longer. You can run a 2618 for long periods of time if power loss is ok.

Kurt