When converting to 3.4 P&C's what are the advantages or disadvantages of the RUF short skirt pistons vs Mahle or JE (longer skirt)?

 

As I understand it, you get more piston slap with the Rufs, which is most noticeable at idle. Perhaps the Rufs would be marginally lighter, otherwise.

I have the Mahle Sports, 7.5/1, 98mm (for a 3.4 if you stay with the same stroke). They've been great.

 

D;
Do not use the short skirt! You will get accelerated piston skirt wear. I have a set sitting in a box that I replaced with JE... There is not enough support. There is a newer casting available with wider skirts.

 

Kevin where did you purchase the JE's from?

 

D;

By the way were close neighbors! I ordered them from JE. I can show you in person the wear pattern on the short skirts pistons.

 

I am very sure Ruf does a lot of R&D before putting their P&C kits on the shelf. Ruf does'nt just build quick cars but reliable cars to. I have the Ruf 3.4 7.5 compression short skirt piston/cylinder kit and have had no problems whatsoever. In short, go for it.If it's some other company, I'd be very but with Ruf, your in good hands.

 

Sameer;

What are you implying (vary)... Have you ever seen a 930 piston in your hand? Have you even seen multiple sets. The Ruf design is 15 years old and there are better Mahle pistons out there. I've had Ruf pistons, and they failed. If you keep your car long enough and drive it hard enough your skirts will wear from piston slap. Ruf does sell good products, but sometimes thing aren't good enough.
<img src="http://boards.rennlist.com/upload/RufvsJE.JPG" alt=" - " />
Here is a picture of one of my 98mm Ruf short skirt pistons with low miles. The photo doesn't do it justice but you can see the bright polishing where the slapping or rocking is occuring on the lower part of the skirt. Yes, I used the JE's instead of the new Mahle's because of the cost issue and having to spend more money to fix an the noise/slapping issue.
EDIT--This is not an endorsement of JE nor a bash on Ruf.

 

I have to agree with Kevin, when I was building my engine over the winter, I initially purchased the RUF pistons because they were about $500 less expensive. However, when looking at them, they are about 1/2 shorter and the weight difference was minimal. It was clear that they would be prone to more piston rock since the skirt is so short. I ended up purchasing a set of the Mahle pistons and am very glad I did.

BTW, Kevin, is the JE piston an 8:1 compression piston? Do you know what the net dome volume is of those pistons? When I CC'd my Mahle 7.5:1 pistons, they came out to 7.22:1 compression and had a net dome volume of 7cc.

 

Geoffrey,
I am sure Kevin will answer, but I was trolling so.....JE will make the piston any way you want it. I have all of mine made to 7:5:1. They provide you with the printed spec sheet. When I get into work I will scan it and post.

We are doing another crazy high HP motor and the owner sent in 8:5:1 3.3 pistons!!

Great stuff with no issues really. I personally have been very impressed and pleased with the cost/quality of JEs...

 

I did think for a split second to use 8.5 to 1. However, I ordered 8.0 to 1. I did cc the dome and I am a hair over 8.0.

 

Now you guys got me worried. I've spent a lot of money rebuilding my motor with the Ruf short skirts. Hope they last.

 

Sameer;
What a perfect time to build a stroker/964 3.5ltr engine. In truth, the longer you wait, the cylinders will become out of round due to the piston slap. You won't be able to do a piston upgrade due to the out of round specifications.

 

The use of short skirt Pistons where weight and friction are concerning factors, is the right decision. The proper taper in the skirt, Rod length, expansion rates, (material used) and clearances are also contributing factors.

If I may add, if noise (slap) and wear are concerns, then the use of JE Pistons is surprising, when there is Piston manufacturers with way better engineering in their Pistons. Not to sling it to JE, my personal opinion is the choice of JE is always based upon cost, not engineering. Good value for $ spent, but there are some concessions that have to be accepted.
From experience, more HP can be had by using other brands, with better dome config's, and other factors. Its a proven thing.

JE, I would consider the Walmart of Pistons.

 

To add one more factor, any shop that uses and sells JE Pistons and the like, do so because of the cost to the buyer, not because of any performance advantages. If engineering quality is what you want, then shop where engineering quality is sold.

 

m42racer;
I am going to have to call your bluff. You are going to have to back up what your saying. JE, Wiseco, Carrillo=Same company=cost saving vs no engineering? You need to look at my picture. Look at the ring configuration, Wide 1st & 2nd ring spacing with the Premier Euro-Goetz oil ring... What kind of other dome design will net more hp on a flat top turbo piston?