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Hello,

I am in the process of building a LS7 Engine for a Street Car and just want to set up the block for Supercharging possibly later on down the road.

I have the LS7 Engine, Factory Steel Crank and Titanium Rods from an engine with 11,000 miles on it. I am just wondering what aftermarket piston to go with. Who on here has experience with these?

I have heard Mahle, Wiseco, Diamond, CP, J&E, Katech, etc are all top brands, my engine builder would like for me to use Diamond or CP, I just want to hear some feedback from those who have used them.

I am concerned about weight and would like to know which piston weighs close to the Factory LS7 Piston Weight or lighter...from my experience the factory piston weighs around 482 grams.

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Katech_Zach

All of our LS7 pistons are lighter than stock - in the low 400g range (most about 420g). Our LS7 piston was durability tested for 422 hours of wide open throttle.

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Jason - Your Stuff is always top notch!!! Do you have any 20% off specials comming up ????? How about a buy 2 sets and get a discount?

Katech_Zach

Thanks. Sorry, no sales coming up. Quantity discounts start at 5.

J HEBERT

The LS7 uses a bastard-length rod, so many companies will not have an "off the shelf" piston and will require several weeks to machine them. I am sure Jason has a couple as pencil-holders on his desk and they most likely have them ready to go

Katech_Zach

LOL. How did you know!? It actually makes a great business card holder but close enough.

BgBoost1

Mahle, Diamond and CP has them in stock and can ship tomorrow. J&E and Wiesco quoted me 3 weeks, so I am sure it will be more like 4.

J Hebert - You have some experience with aftermarket pistons, which ones have worked the best for you in the past? Do you have any experience with the Katech Pistons?

fperra

I just had custom Arias pistons built for my engine. For an extra $250 they will expidite your order and get the pistons to you in about 2 weeks. Whatever you do, don't buy off the shelf pistons until your builder hones and measures the bores. I bought Weisco off the shelf pistons and had to send them back because they had too much clearance.

WeaponsGradeTorque

They may be lighter, but do they combust as cool as the cast pistons?

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fperra - thanks for the tip! You might happen to know the Rods and Crank going into this engine Thanks again for the GREAT SHIPPING!! I did not think to consider Arias.....

I don't think we are planning on Boring the cylinders just a simple hone to get them in 100% perfect shape, the block looks great now, I just want it to be 100% for my customer!

It seems that Diamond, CP, Katech, etc all sell sets some at 4.127 and 4.130 for the honed cylinders. That is what I am looking for!!! You are correct Wiesco only stocks 4.125 stock bore. My engine builder is telling me that he wants to hone the cylinders to fit the pistons once he has them!

Katech_Zach

If you order 4.130" pistons that is fine. If you order 4.125" pistons and it needs any more than a touch hone you will not be able to run the 4.125" pistons and you will need to order 4.130" pistons anyways.

J HEBERT

I run the diamonds in my current motor, but as Jason stated, if the block is used u would want .005 oversize and hone to spec. This is the only way to insure minimal leak-down and good piston fit. (unless u want it to sound like a diesel)

Mahle also makes a damn good piston, I have them as factory units in a few supercharged and 1 turbo application and they run at well over 100hp/cyl. at 8600rpm for 10-15mins WOT at a time. Hundreds of hours if that tells u anything.

Halltech

Katech is the only way to go, in my opinion. These are their 12:1 CR 2618 T6 slugs for our E85 motor:

yanniz

CP with no doubt

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Mahle - I have ran those before with great success but on a ford supercharged 331 engine. Having a 4.130 on the shelf 460 grams and at less than $600 for a set with rings and pins.......that sounds quite tempting....I might have to go that route!

Yanniz - I have 2 pm's telling me to go with CP...why have I never heard of them?

Halltech - I saw the posts on that engine....killer set up!!! Have you ran the engine yet in a car, and is this your first set of Katech Pistons? Did you run them on your C5 Turbo set up?

BTW...does anyone know who makes the stock LS7 Piston.

Thanks everyone for the feedback!!! I appreciate the opinions!

FNQWK

im going with diamond forged nitrous pistons(#11580) in my rebuild.
stock crank/stock rods
ls7 forged flat top w/-2cc valve reliefs,4.125" bore/4.000"stroke/
6.077"rods/1.170"comp height/.927x2.500 wrist pins

Katech_Zach

Mahle

DSteck

The only pistons I have experience with are CP from my days in a Subaru shop. I never saw a piston break... but I saw plenty of other engine components break. The worst thing I ever saw was a ringland bend, but the cylinder still held compression... although, the rod bearings were pounded out of all four rods. The guy I worked for has built probably close to 1000 engines using CP pistons, and I can't say I've ever heard of a single one having a piston failure, and many of these are doing over 100hp per cylinder.

When I finally get the courage to pull my motor out myself, I'll be using CP pistons (but I can get them for cheap).

You know Katech pistons have tons of research and backing, and the Mahle and Diamond pistons have proven to work well also. Any of those would work great.

J HEBERT

Of the manufacturers mentioned, the bigger concern will be the fit and actual alloy used. The thermal-expansion rates differ and there are 2 alloys u can choose. This is where compromise starts. Decide now on how much boost and overall usage of the car. Get w/ your builder, make a plan and make sure the machinist is not high when he preps the block (double-check his work, just 'cause u paid him don't mean it's right!)

IPS Motorsports

We typically use diamond pistons in stock size bore applications (NA, Boost, N2O ect), good products for a good price, with a good turn around time. We typically also use 4.130 on sizing for the similar mentioned reasons.

Ceteris Parabis (all else the same) Katech's recently released pistons seem to be the most specifically engineered for the LS7 currently, and for the premium paid, you are recieving a quality product, with a strong r&d foundation. I would honestly lean heavily towards this product now with the data I have seen.

Brandon