81mm 906 cylinders

Henry Schmidt · Henry Schmidt's Garage

The testing begins.
We now have the first of our new 81mm 906 cylinders. They are not for sale yet but we hope to have them soon. Note the new sealing surface never offered before. It will allow you the put 2.2 heads on a 2.0 engine.

kenikh · 06-13-2006, 10:01 AM

I assume these are Nikasil vs. Chromal (due to lack of dimpling)? Since I am no expert, are the cooling fins on these the same or different from original 906 cylinders? Can you compare/contrast these vs. bored Birals?

Are these going to in the same price range as the other Nikasil kits?

Henry Schmidt · Henry Schmidt's Garage

Nikasil and the fins are an exact replica of the 906. I fact a 906 cylinder was used to make the mold.
Nikasil cylinders cool better and of a more consistent ovality than Biral.
Biral barrels are notorious for getting out of round very quickly especially during racing applications.

tadd · 06-14-2006, 12:23 PM

Are they only for use with the 2.2 heads or can the casting simply be machined for 2.0 heads? Any idea of what the offering time frame will be (months, a year)?

tadd

Henry Schmidt · Henry Schmidt's Garage

The best way to use 2.0 heads with these cylinders is to machine the heads to fit. This conversion has been done for years. 2.0 heads on 2.2 cylinders (84mm) or 2.0 heads on 2.7 mm cylinders (90mm 2.5).
After testing we're looking at 45 to 60 days.

tadd · 06-14-2006, 02:10 PM

So really the answer is no, they are not for the 2.0 heads (since it would be kind of dumb to take a hard to find set of 69S heads and cut them up to 2.2 spiggot size).

Cool product regardless. Thanks for bringing it to market. Kudos.

Got any pictures of the, I would assume, matching pistons (to use 2.2 heads)?

tadd

Henry Schmidt · Henry Schmidt's Garage

Quote:

Originally posted by tadd
So really the answer is no, they are not for the 2.0 heads (since it would be kind of dumb to take a hard to find set of 69S heads and cut them up to 2.2 spiggot size)...........
tadd

What is dumb is not availing ones self of an obvious improvement on the cylinder design.
We could have made these cylinders fit the lame 2.0 head gasket style seal of the 2.0 head but we chose not to muddle along with a bad design in favor of a far superior design.
If our goal was mediocrity we would not improve a product. We could continue on using the lamest of designs and forgo any gains in the product at all. No oil bypass mod, no case savers, no oil pump upgrades and so on.
Porsche did the same thing when they discovered that their head design on the 964 was faulty. They didn't think to save the design, they looked at the problem and designed a cure. The cure was to redesign the cylinder and cut the old head to match. One might say that early 964 heads are hard to find so why use the new cylinders? That logic deserves a swift kick in the rear. The far superior cylinder warrant machining the heads.

tadd · 06-14-2006, 03:23 PM

Ok, color me an ignorant and needing an education. Care to step up to the plate?

Not to put too fine a point on it, other than the shallower combustion chamber for improved detoniation resistance with a single plug, and the 1 mm larger valves from the narrower valve tilt what makes the 2.2 so special over the 69S heads? I do see the 2.2 advantage with a single plug and the savings in the production cost (in the 60s - no fancy distributor and double ignition componets). Parts left out don't fail or cause warrenty repairs.

I ask this as a serious question as I have had both types on my mill in the last few weeks for boring/blending of the ports as well as twin-plugging. I'm a chemist, not a porsche mechanic, but I like to play, get dirty, and learn.

From my observations of how much material was left (and where) from boring the intakes to 38mm it was quite apparent that the 2.0 heads (70T from a 914-6) have a straighter shot into the cylinder than the 2.2s. This makes sense due to the larger radius of curvature of the combustion chamber allowing for a steeper valve angle. We all know that tubes that flow material that must curve restrict flow and the larger the radius, the more restriction.

So if one can 'correct' or band aid if you prefer, for the bad flame propigation from the really high dome required by twin plugging, might not the 69S head possibly have a larger ultimate flow potential? With less curvature there would also be less fuel fallout as well.

If you have dynoed two motors that differ only in the head types and there is a significant difference... well, good science doesn't lie and that is a kick in the rear!

tadd

304065 · 06-14-2006, 05:05 PM

Henry, congratulations on your new product candidate.

What kind of testing are you putting them through?

Henry Schmidt · Henry Schmidt's Garage

Some how this discussion has become about the benefits of the 2.0 head over the 2.2 head. That was never my point although I would argue that the bigger valves and flatter valve angle would offer better flow and combustion on a flatter piston of equal compression is a substantial improvement, my point was that my cylinders seal better and cool better than the alternative cylinders.
My cylinder were designed to work well with both 2.0 and 2.2 heads. What I was saying is cut the heads to fit EVEN PRECIOUS 69 "S" HEADS.
Nikasil aluminum cylinders cool better, offer a better friction coefficient and wear better than biral , chromal or straight cast iron.
The large flat sealing surface offers a far more stable platform for high pressure sealing and with a good set of head studs (Supertec studs come to mind) far less possibility for lifting.
We run our 2.0 race engines at or near 8500 consistently and 2.0 flange and gasket system is inferior to my design.

tadd · 06-14-2006, 06:26 PM

I followed what you were saying just fine.

What I was trying to get to is that your product is unique. The other 906 clone cylinders are also aluminum/nickasil but also use the factory 2.0 sealing. So it is painfully obvious that if you do cut your hard to find S heads, then you are 'stuck'. You cannot use any other 2.0 cylinder unless you find someone to weld them up and turn them down.

Would most people cut there heads? My guess would be no, they will just switch to the 2.2 head for its 'advantages' listed previously - not to mention the cost of valves alone. I personally was going to use 2.2 heads for a 2.0 motor and was super interested in your product as you had mentioned it in other posts. Somewhere along the line I started thinking about the 2.2 'advantages' and decided to be a bit more 'vintage' and drop back to the 2.0 914-6 heads.

I assumed that it would be easy during the final finishing to have them machined to 2.0 spec so I asked.

You posted a new product, I had a few questions - so I asked. Go figure.

BTW, it was porsche's design - you just applied it to a 2.0 cylinder. Clever twist, yes. 'Yours' no.

tadd

andrew15 · 06-14-2006, 07:03 PM

Gotta hand it to you Henry -
You've brought a lot of great products to the market (cylinders, twin plug distributors, MFI stuff, head studs, and the list goes on).
The passion definately comes through and I always appreciate the knowledge you share with the board.

Tadd - I don't think Henry was taking credit for coming up with the sealing surface. He was taking credit for applying it to a combination previously unavailable.

Thanks,
Andrew M

jluetjen · jluetjen's Garage

I'm not sure that Henry is trying to take credit for anything. I think (as was mentioned earlier) that he's invested his own money to develop a product that applies later (and better) technology to an earlier product. If you chose to invest your money in the change is up to the buyer, but Henry is doing everyone a service by making the choice available.

davidppp · 06-15-2006, 10:33 AM

The flow through heads is really hard to predict IMHO.

I do not think the available data of which I am aware suggest a huge difference either way in stock form.

And anyone who has had to purchase valves for 69S heads will appreciate the eye-watering cost...

Henry, please could you enlarge on the ehad sealing you have designed?

Is it like the 3.2 engines with a shallow angle cut..3% IIRC?

I cannot see a groove for the c-seal rings...

Kind regards
David

davidppp · 06-15-2006, 10:36 AM

PS, I will volunteer to intensively test these cylinders in a very hot motor!
The batch of 69S pattern German Pistons are on order BTW..

Kind regards
David

kenikh · 06-15-2006, 10:39 AM

Batch of '69S pattern pistons on order? Who is making them, Mahle?

davidppp · 06-15-2006, 11:44 AM

Hello, Kenik.

Not Mahle...but this company is the supplier to some of the current F1 teams ...if you do not mind, I'd like to keep their name confidential for a little longer..?

When we are fully happy, and have stock, we will post full details...but I am confident these new pistons will be an improvement over any 911 piston currently available to the public..

Partnered with these new barrels, Mahle will have for the first time some serious quality competition..

Kind regards
David

Kind regards
David

kenikh · 06-15-2006, 11:48 AM

Thanks David! I have a good guess who is it, but won't say. I assume other CR options will be offered?

tadd · 06-15-2006, 11:56 AM

David:
Can you give some tidbits like weight? I will certianly be up for a set.

tadd

davidppp · 06-15-2006, 12:57 PM

Hello, Tadd.

I think you may already have had some discussion about these!

I'm again sorry to say that although weight will be lower than currently available, the precise figure must wait until after full proof..

They have some very nice pins, and rings...

Ring performance is IMHO crucial to high-rev life..

Kind regards
David