choices in Mahle hc p/c's?

[911SCfanatic]

Seems like Andial is the only place to get high compression 90mm Mahle pistons. It appears everyone else who sells them sources them from Andial. I'd like to get the Mahle 9.5: 1 p/c's, but at about $3500 it's a bit hard to swallow. Anyone else have other souces or thoughts? (I already know I can get custom JE's for much less, but was thinking of long term reliability and durability).

[Jim Richards]

Bill, I think there's a fair number of folks using JE's for engine's that they're hoping to get a lot of miles out of. Mahle's have the stronger reputation, but who knows.

[911SCfanatic]

The thing that has me hesitating with the JE's is 1) noise, 2) oil consumption, and 3) some saying that if you plan on going the track often (which I will eventually) plan on replacing the JE's now and again. The obvious question is what is "often." I'm going to be at the upper end of "acceptable" compression for single plugging, so I thought the Mahles would be the better way to go. If I was going to run 8.5:1, I would think twice about using the JE's. Don't know if my reasoning makes sense, but I guess that's what I'm inclined to think. Someone please jump in and tell me my head's up my butt, if it's warranted.

[MotoSook]

I wonder about the JE Pistons too! Is the current opinion current? That is, do the JE's really have poor performance (longevity) or are we working with old empirical data.

[jpnovak]

I too wonder. I have a set of mahle 98mm PCs that should come out to about 9.8:1. I have been tossing the idea around about ditching the pistons for some higher compression JEs to go with my twin plug setup. I too am concerned about longevity.

Maybe we should pose the question to the 911 tech board. OK, I will ask.

[Plavan]

J&E pistons are great! My dad and I run them in all of our race motors. I just sold a set out of my race motor and they were perfect. I have another 84mm set that are just as good that I am selling. My dad has been using the same 906 spec J&E's for over 3 engine rebuilds. Another serious advantage of the J&E's is that if you ever throw a rod, and a piston goes south, you can order just one piston.... Try that from Mahle or Andial, they only sell in sets.
There is nothing wrong with J&E pistons. They are top notch. You will not be disappointed.
We have never had to replace a J&E piston due to "wear". Now thrown rods if a different story.

Also noise???? where did you hear that J&E's are noisy? Oil consumption???? never heard or seen anything different.

[jpnovak]

Thanks for the input. how often does your dad rebuild? Once a season or due to other problems?

[Plavan]

Originally posted by jpnovak
Thanks for the input. how often does your dad rebuild? Once a season or due to other problems?

Hehe.... alot of factors. Usually if everything goes well you replace the bearings, etc. after 40 or so hours. He has had bad luck with motors these last few years. These failures have nothing to do with the pistons.

[Jim Richards]

It might we worthwhile to look at this JE issue from the standpoint of the person rebuilding an engine with the hope that it'll last 10 years or 100k miles.

[ChrisBennet]

Has anyone recently heard a noisy JE piston? Years ago I asked EBS about this and they said something to the effect that at one point, JE's made only racing pistons for 911's and yes they were noisy. Since then they've come out with pistons that were more suitable for street cars and the noise is a thing of the past.
-Chris

[MotoSook]

With better machining (more like better material and understanding), the piston slap that was reported should be a non-issue, correct?

[911SCfanatic]

One engine builder I talked to said the JE's are noisy and have greater oil consumption due to the larger clearances between the pistons and cylinders. AFAIK, the JE's do require larger clearances. If this is true, there will almost certainly be more noise and oil consumption. In particular, increased clearance at the skirt will result in noise under cold conditions heard as piston slap. Never heard a JE vs. a Mahle, but if there is a difference in clearance it would seem to support what some have said on the issue. A couple of engine builders I have talked to have also said that if your going to do engine rebuilds frequently, then there would be no problem using the JE's, which to me implies that if you don't rebuild frequently then you might have problems.

Jamie, thanks for asking the question in the other forum. I want to hear from 1) someone running high compression JE's for 10's of thousands of miles, 2) someone running 8.5:1 JE's for similar miles, and 3) someone running Mahles and JE's.

[911SCfanatic]

With better machining (more like better material and understanding), the piston slap that was reported should be a non-issue, correct?

What I have gathered to be one of the differences between the JE's and Mahles is the materials. Mahle uses a material that has coefficient of expansion similar to the cylinders enabling tighter tolerances. JE's material does not so closely track the cylinder's coefficient of expansion so JE compensates by machining the pistons so that they have the desired clearance under operating tempertures. This results in a piston that has larger clearances when cold, and thus, more noise and oil consumption.

[cnavarro]

Bill, you have it right on the money. The mahle cylinders are a 339-0 "high-silicon" content aluminum and the pistons themselves have a similar high silicon content, hence the like expansion rates and tighter clearances. This can be mimicked by using the 4032 high-silicon forging by JE. The big problem I see is that JEs "recommended" p/c clearances are exaggerated in most cases and can be tightened up. On the other hand, those desiring tight clearances and the 2618 high-strength forging from JE could pair them with the cylinders we manufacture (and are available from Pelican BTW), which are designed for use with this forging, since the expansion rates are very similar. For example, we can run a .0017-.0019" total p/c clearance with 98mm Nickies cylinders with the 2618 forgings from JE. When contrasted with JE's, it's a bit difference (taken from a post by Souk on the other thread about JEs):

"A 98 mm piston made of 2618 requires 0.0035-0.0045" minimum clearance, while the 4032 piston requires 0.0025-0.0035" minimum clearance."

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

[911SCfanatic]

Alright, Charles, you have me intrigued. I was headed in the direction of a 9.5:1 (or so) 90mm RS-type Mahle p/c's. What would that set-up run me getting the JE's, Nickies, ARP bolts? It seems that its more pricey than the Mahles without the long track record. What's the benefit--being able to run custom JE's in a cylinder that enables a small clearance? The heat dissipation is better with the Nickies, so can you run an even higher compression to get even greater hp? For example, could I run 10.5:1 or greater without twin plugging? What's the end benefit?

Is there longevity data on the nickies? What's the highest mileage and most severe use that they have seen?

[cnavarro]

As far as track record, I have to say that i've made about 1000 cylinders in about four years, without one single failure. A good majority of the cylinders have found their way onto type 4s, type 1s, as well as more recently Porsche 356s, 912s, and 911s. Our cylinders have been used in vintage racing, drag racing, and e/f production for years now. I've made cylinders even for vw powered aircraft. The largest volume engine builder to use my products has been Aircooled Technology.

Before we sold a single cylinder, we put a 200 HP 2.6 L type 4 through the paces with ~30,000 miles in 18 or so months. Teardowns every 10,000 miles showed that the bore remained true without any unexpected wear, high oil consumption, or loss of compression. Head sealing was noticeably improved over cast iron cylinders (all that was available for the porsche 914 at the time). Since then we have done side by side dyno comparisons of cast vs biral vs nickies and we've contracted out to get some testing done on aluminum mahle vs nickies in a 2.5 limited displacement racing application.

The secret (not really a secret) to the product I offer is to base it on a proven product, then make improvements through better processes and materials. Early on I had many cylinders analyzed to see what aluminums were used in the casting done by mahle and KS. Mahles were a 339-0. On average, the proprietary aluminum I use is a minimum of 50% stronger with twice the thermal conductivity. Add more fins and your getting even stronger and adding even more cooling.

Primary benefits would be improved cooling, longevity, and overall performance. Reduction in cylinder temperature increases intake charge density and makes more power- this we have proven on the dyno! Improved cooling comes from more fins, increased thermal conductivity, and improved fin pitch, which increases plenum pressure, making your cooling system more efficient. Our testing has found that we can reduce fan speeds or blade count and maintain proper cooling.

We've done over 13:1 without dual plugs on bores over 100mm. Pump gas, well it all depends on the static and dynamic compression, and we've been able to push 10.5-12:1 on pump with proper combustion chamber design, good quench, proper deck height, etc, and that's even with the inferior compact wedge combustion chamber.

I can't claim to have the track record of a mahle, but I have taken the time to engineer a better product where no corner is cut and what you get is the best possible product. As a side note, I use Millennium Technologies, the plater used by EBS Racing for replates, who backs their work with a lifetime warranty on our cylinders. A nice bonus I think.

Now for the painful part, price. Well, I can't compete with every Mahle product, but I do try to be fair and honest in my pricing with a flat rate, since each cylinder really does take me roughly the same amount of time, material, and labor to develop. If you're comparing my products to andials, you're probably going to be within a few hundred dollars, but you get a better cylinder, lifetime warranty on the plating, and a fully custom piston, designed to your specifications, not some 20 or 30 year old piston design. And yes, since you can use the 2618 forging with Nickies and run tight clearances, you end up with a stronger piston than the mahle.

Don't get me wrong, my cylinders aren't for everyone or needed in every application, but it's always nice to have another option for a better cylinder that although might be more expensive, delivers for every penny spent.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

[911SCfanatic]

Thanks for the response, Charles. Do you have engine building/design experience to determine appropriate cam profiles, porting, fueling, etc. to take advantage of your p/c's. For example, if I can run 10.5:1 single plug how aggressive of a cam profile can I run for a 75/25 track/street application? Should there be any tweeks in porting? How should MFI fueling and/or the distributor curve be adjusted if at all? I guess I have to know how to take advantage of the benefits.

My knowns for this rebuild are:
1) 2.4 7R case, spigots bored to 97mm
2) MFI
3) single plug

What type of engine can I make and with what range of power? Or maybe I'm looking at this from the wrong angle. Do I decide on the cam profile and porting and then just use the highest compression ratio I can use (with some safety margin) without having to twin plug? Someone set me straight here on an overall design strategy (with the above knowns).

[cnavarro]

To be 100% honest, for the 911 I have to rely somewhat on the suggestions of those enigne builds experienced with using my product as well as with vendors like EBS. Also, texts such as Wayne's 911 book and Bruce Anderson's books (i have both revisions, just for thoroughness), are great references for what was done and is proven. Shoot me an email at charles@LNengineering.com and i'll be more than happy to work with you to hammer down a good combo, regardless of whether or not you do purchase anything from me, since I enjoy doing the research and discussing builds such as yours with those resources available to me. This service and research is something I consider as standard as part of the purchase process, to make sure the customer gets the best bang for the buck and best combination possible.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

[911SCfanatic]

Honesty is something I always respect. I never expect people to have all the answers since no one ever can. Sounds like you have a great product and I'd like to talk to you more about it. I will contact you tomorrow. Thank you for your thoughts so far.