2V4V

Aaron,

There is no reason not to use 951 pistons that I am aware of. In fact, I know they have been used. They are a nice (factory) quality piston, properly coated to work in the alusil block.

If I were going aftermarket, I'd go Mahle - they are one of Porsche's 2 OEM suppliers and they have their custom manufacturing here in the USA.

4.5 and 4.7 (USA) are both relatively low comp motors - unless you're running running a kompressor

4.5 = 8.5:1 thru MY79
4.5 = 9.0:1 MY80-82
4.7 = 9.3:1 MY83-84

HTH,
Greg

John Struthers

Brendan, Aaron, Greg,
Brendan...I flat don't know,
but I would lean toward what HAS worked with other build-ups for spec.turbo, SC'd & nitrous huffers.
Arron , Greg, you probably know this... there is a difference between CHROME and HARD CHROME. The latter being one hard mother and has numerous industrial applications. I wonder though, how easy it would be to get a uniform (thickness) coating the length of a interior circle - bore -
or uniformly coating a piston. Believe me, if it adheres its staying. The problem here is uniformity and trying to machine to those
10-thousandths without chipping. Yeah, there are some great machine tools out there but have you ever tried to resurface/machine a galled brake rotor or flywheel? I think uniform coating and the machine work is where the problem lies with
coated pistons and bores. And, of course, by the very nature and metallurgy hard chrome becomes labor intensive to hone with heat buildup, -remember only surface cooling by cutting fluids during the process- no internal water jacket cooling. So you can easily excede engine operating temperatures and change the chrome into something with different properties due to pure and simple heat. I, also, have some questions on
where to put my faith in regard to compression values.
I have noted that Performance Automotive has Engine codes,displacement, Comp. ratios, Tran.model/type, HP, by year and model. Point of fact is that it pretty well matches up with what quotes and references I see on the boards.
That's all well and good until you or I are fixin' to invest a pile of pre- Enron crash, stock money in the powerplant of our dreams.
In particular, I have posted, in the past, a query as to what happened to the missing series number engine codes. Example what happened to the M28-01, 02 engines. The M28.04, .05, 06, 07, 08, 09, 10, 11, 12. Then the M28.14, .16, .17, and .18. The list goes on... I was curious, was Porshe similar to Ford back in the 60's. The odd stuff, you know...like a Country Squire station wagon arriving in suburbia with a strange 390CI FE block with a forged crank, 427 heads, and an interceptor intake - talk about your sleepers!!!
I loved it though I looked a little strange hangin' out at the Big Boy with the motor heads and all of those now priceless hot rods.
Anyhow....
Check this out... Yeah, Performance Automotive
and others quote -see Greg's post- compression ratios for specific year/models but while I was browsing my Owners manual fo fuses/bulbs/relays
I noticed something a little odd.
Lo and behold 1982 928, and 928S engine specs.
The 928 4.5L is listed as a M28.09/.10 motor with a 10:1 compression ratio. AND the 928 S as a 4.7L M28.11/.12 engine running 10:1.
The only difference between the engines as related to specific model appears to be one series number was for the standard shift say the M28.09 and the M28.10 for the auto. Same applies to the S model with the M28.11/12 series 4.7L.
So here is a neat twist, I found some of the 'missing' engine series numbers (yipee)in the owners manual, but, the compression ratios aren't jibing with other sources. The HP numbers are off, too.
SO... I've got a couple of points to make.
1. We, all of us, need to get into our owners manuals, get some hard data from the Zuffenhausen Kids engineering/test archives, get a base line Dyno library and compile it all into ONE UNIFORM 928 Engine BIBLE broken down by Year and Engine Series. God knows there have been and will be a bunch of 928 gatherings with and without dyno runs where we can, actually, see the hardware and gather data for the bible. If we can get off of our collective butts/fins and check out our individual sharks and their respective owners manuals ...more data.
2.Do we have accurate data in the owners manuals? If so, it shows the need for an Engine Bible, a purge/INQUSITION of the bogus data, where ever it comes from, would be in order.
If I was building a high dollar Porsche 'grunt' motor and was going to turbo/SC/ and, or, nitrous inject it I would be highly pissed when the pistons holed and the rods started sneaking out of the block.
Ideas?
Keep em' rolling.
John S. and Pattycakes

<img src="graemlins/oops.gif" border="0" alt="[oops]" />

Steve Cattaneo

Brendan,


I have not done the process of nicka/sil yet. I will have my 928 block done soon. I have been working on the heads, which will determine which pistons are used. I have spoken with different Porsche engine builders; they have done 944 engines (alusil bore) treated with nicka/sil. They haven’t done any 928’s; they say there is no demand for them.

Nicka/sil is not a new process. It was development but mahle and Porsche AG. It was used in the 1970’s in 917, 935 turbo Porsche. It is still being used today in 911, Mercedes, mercury outboard engines, snowmobiles, chainsaws, 4 and 2 stroke bikes built in Japan.

Benefits of nicka/sil:

-Less friction between cylinders and piston (more Hp)
-More durable then alusil
-You can customize your pistons for your particular application
-Forged
-Low compression, high compression
-Flattop
-Dome
-104 mm pistons

I will not use a used piston in my engine. Think about it, that piston has been hammered. It has been exposed to high temperature and pressure for over one million cycles (intake through exhaust). Have you priced out OEM pistons lately? Another alternative could be a nicka/sil-coated piston ran in an alusil bore. The skirts will not be exposed to the combustion of fuel. If Mahle developed nicka/sil I am wondering maybe their pistons are treated with nicka/sil. I am aware BMW had a nicka/sil coating problem on some of their engines. Maybe it was a bad production run of their nicka/sil treatment, since no other car manufacturer who uses this treatment has reported any problems.

My advice to you is to use whatever you or your engine builder feels more comfortable with.

<a href="http://www.rennsportsystems.com/~porsche/2f.html" target="_blank">http://www.rennsportsystems.com/~porsche/2f.html</a>

<a href="http://www.rpmsbigbore.com/repair.htm" target="_blank">http://www.rpmsbigbore.com/repair.htm</a>

<a href="http://www.hydrostream.com/wwwboard/messages/2252.html" target="_blank">http://www.hydrostream.com/wwwboard/messages/2252.html</a>

<a href="http://www.brisonaircraft.com/cylinders.htm" target="_blank">http://www.brisonaircraft.com/cylinders.htm</a>

<a href="http://www.mahleinc.com/motorsports.htm" target="_blank">http://www.mahleinc.com/motorsports.htm</a>

<a href="http://prp-inc.com/mahle.htm" target="_blank">http://prp-inc.com/mahle.htm</a>

<a href="http://www.mongoosemachine.com/cylinder-plating.htm" target="_blank">http://www.mongoosemachine.com/cylinder-plating.htm</a>

<a href="http://www.finishing.com/1600-1799/1671.html" target="_blank">http://www.finishing.com/1600-1799/1671.html</a>

<a href="http://www.fortunecity.com/silverstone/lancia/58/911/911_81.htm" target="_blank">http://www.fortunecity.com/silverstone/lancia/58/911/911_81.htm</a>

<a href="http://silverstone.fortunecity.com/ferrari/464/bmw_digest_sulfur2.htm" target="_blank">http://silverstone.fortunecity.com/ferrari/464/bmw_digest_sulfur2.htm</a>
<img src="graemlins/yltype.gif" border="0" alt="[typing]" />
Good luck
Steve C
The Great white
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/yltype.gif" border="0" alt="[typing]" />

Steve Cattaneo

John,
The M28/01 and M28/02 engines were used in 77-79 Euro, M28/02 AUTO. 4.5L 229HP 8.5:1Comp; M28/01 5speed 4.5L 229HP 8.5:1Comp;

M28/13 5speed US 1980 220HP 9.0:1Comp,
M28/14 auto US 1980 220HP 9.0:1Comp.


Steve C
The Great White


<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

John Struthers

Steve C.
The data accrues.
But, where did ya find it? For Reference ... not hammer and tong.
I figured it had to be there. In the early models.
Performance Automotive is showing a big gap from around 1980 where they jump from the .03 to the
.13. I'm guessing it has to do with Euro and S models. Do you know, if for instance, would one years Euro be an American S model a year or two later? Another reason I want the Owners Manual(OC) info. Would also like to bump torque, HP, Timing and rpm as a way of figuring out what's what.
I know some of us sent off for our OM's late in the cars life. Some might have engine, head, cam, and intake swaps. Certainly, folks have played with the exhaust, timing and fuel. What I'd like to see is a compilation of the best possible engine combo's primarily 84'and earlier models as
there was only a 2mm change in the bore dimension the stroke remaining the same giving us, roughly, 28,000 short blocks world wide, prior to any attrition. The newer models -with the 85's and early 86's being the oddballs- comparatively, have an enormous number of blocks available. Which is why someday I hope to have my 82', a late 86 1/2, and a 90GT. Keep da numbers coming.
Randy, Can I put this in the Performance section so it doesn't turn into the never ending 20 page post?
Thanks again Steve.
John S. and Pattycakes <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />

Tabor

[quote]Originally posted by gbyron:
<strong>Also, the majority of 944 turbos were of the 2v variety, so if you use them with 4v heads there will be clearance issues.</strong><hr></blockquote>

I just thought I should point out that there where zero 924/944/968 production turbo cars with 4 valves per cylinder. The only one that I know of was a factory race car called the 924 GTP (one manufactured), it was never available to the public.

Even the 968 Turbo uses a 944 Turbo 8 valve head.

Steve Cattaneo

Tabor,
On Saturday I was at Rick Deman’s shop (Deman motor sport), there was a 944 head on his workbench (Broken cam chain). That head had two cams; 16v
The owner, a 944 was sitting on the lift; I thought I saw a turbo.

Steve C
The Great White

Steve Cattaneo

John,


The 928s were not meant to be a torque monster. Its power band is from mid to high RPM range. It was engineered as a high performance super sports car. The best immediate torque improvement modification would be a set of 4.11 differential gears, HP is a $$$ game. I can get 500 HP out of a small block Chevy for $3,000 in parts. On a 928 $3,000 would BUY you pistons, rings, and an engine gasket set. The more I research my HP project, the more I’m inclined to go with turbo pistons and a super changer. <img src="graemlins/r.gif" border="0" alt="[king]" />


Steve C
The Great White
<img src="graemlins/c.gif" border="0" alt="[ouch]" />

Aaron Rouse

Anyone know of the best place to get 951 pistons new or even used?

I was told PowerHaus sold used ones for $50/each however I contacted then and they went up to I think $160/each for new ones and said a new set would be like $3600 for 8. They offer custom made Mahle pistons as well and 8 of these would be $2800. They recommend getting them ceramic coated and that runs $200 total for 8 pistons. PowerHaus claims to know of one place here stateside that can coat JE pistons with the right coating for our blocks but they said they have never used them because the heat expansion rate of the piston material would still be a issue.

A friend of mine ran 12 lbs of boost on his twin turbo 78 928 with a bone stock motor with god only knows how many miles on it. He ran 8 lbs for sometime as well before stepping up to 12 lbs. He had no timing control either, just a Haltech F3 for fuel control. The motor never blew a head gasket, the only problem he ever had was heat issues, most due to his turbo design. His example is the reason I am leaning more and more towards a stock US 4.7L with 10-12 lbs of boost from my two turbos.

John Struthers

Steve,
Agreed, but we have some fairly, quick cars off the line anyhow. A function of weight, cam, intake, balance, HP, and of all things those gear ratio's.
Youse guy's building these big air pumps will no doubt have adjustable rev limiters cause the way I see it the Tach needle is going to have whiplash. I kind of like the semi-long wind out I have right now - it's like an older GS 1100 Suzuki, everyone else bangin' gears and I'm still pulling away in second-. Ultimately, the Chev is the way to go(sorry purists) even if I had the cash to build a 6.4 in the end I would have a complete 'spare' chev. And unlimited lobuc parts.
Besides my thoughts are that there were less than 300,000 blocks of all types made for the 928 - assuming the chassis numbers/total production listed in Performance Automotion are accurate.
Figure a dozen or so are coffee tabels, and at least 1/6th of the production is likely scrapped by now. God only knows how many are parked with a missing T belt. Doesn't bode well for the Concours 70 years from now. Are you thinking SC for durability or raw HP?
Sounds good Aaron!
Later youse freakin motorheads. Keep posting -can't wait for Abby's results...
John S. and Pattycakes
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" /> <img src="graemlins/a_smil17.gif" border="0" alt="[blabla]" /> <img src="graemlins/xyxwave.gif" border="0" alt="[bigbye]" /> <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

BC

Brendan,

I have not done the process of nicka/sil yet. I will have my 928 block done soon. I have been working on the heads, which will determine which pistons are used. I have spoken with different Porsche engine builders; they have done 944 engines (alusil bore) treated with nicka/sil.

Thanks Steve, for your response.
..Could I ask which shops those are. I have acquired some research that says there may be more durability if th eengin eis NOT touched, in the bore, an dthe money is spent on the 3k mahl pistons. If that is verified, fine - but if this coating could work, I would be very interested in it. You must understand that though this process has ben use don 911s, it is relatively untested on our cars. I am not so sure our cars are THAT special, but the engine design IS different.

Nicka/sil is not a new process. It was development but mahle and Porsche AG. It was used in the 1970’s in 917, 935 turbo Porsche. It is still being used today in 911, Mercedes, mercury outboard engines, snowmobiles, chainsaws, 4 and 2 stroke bikes built in Japan.


...Didn't mervury marine Do the engine fro thr LT-5 (Zr-1) or was that Lotus? That was an AL engine...


Benefits of nicka/sil:

-Less friction between cylinders and piston (more Hp)
-More durable then alusil


..well, to say that would mean that the 928 engine, instead of being able to reach 200k without a rebuidl, would reach even MORE miles? I guess wish to say that I am VERy INTERESTED in finding out your experience as it unfolds.


Have you priced out OEM pistons lately?

..Like Aaron says - its about 3600 for a set.


If Mahle developed nicka/sil I am wondering maybe their pistons are treated with nicka/sil. I am aware BMW had a nicka/sil coating problem on some of their engines. Maybe it was a bad production run of their nicka/sil treatment,

..Sulfur, found in south-east gas tanks, was found tobe part of the problem, as I understand it. IT corroded the material. I could have also been something else.


My advice to you is to use whatever you or your engine builder feels more comfortable with.


..Well, I do hope that I find an engine builder that has an open enough mind to listen to me and accept my research....

Again, thank you for yoru time Steve, please keep us posted.

brendan

<img src="graemlins/burnout.gif" border="0" alt="[burnout]" /> <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

2V4V

Tabor,

Perhaps you missed it (if you blinked you could have) but there was a 16v 944 Turbo. It was called the 944 Turbo S. Available to the general public, and sold in the US market.

Engine numbers were: 47 J XXXXX

Greg

Carlos

Hey guys if you're interested in high tech coatings check <a href="http://www.swaintech.com." target="_blank">http://www.swaintech.com.</a> I have the impression that these guys can solve a multitude of problems all the way to ceramic brake rotor coatings.

Erik - Denmark

Hi Bredan, Larry, Dr.Bob, Jim V, Jim Nowak, Steve, Aaron, Jay, Greg, John, Tabor, Carlos
I want to add one comments to your Nicka/sil - Alu/sil discussion:
In 1998 I visited Firma Tailacker, Stuttgart for getting my block bored.
Tailacker is doing the repair of 928 blocks for Porsche, and was recommended to me of Porsche.
Here I saw an interesting thing - For the 5 liter (100 mm Ø boring) they installed an app. 2mm thick Nicka/sil lining.
They bore the block with a recess at the top - Freeze the lining and drop it into the block - Plan the top and voila you have a 928 block with Nicka/sil lining.
They told that's developed of Mahle and Porsche, but only available for 100 Ø boring.
For sure that's a good solution!
Regards from Erik in Denmark

Fastest928

I have a sleeved block from Tailacker, and it uses a 390 sleeve...it is not a nikasil sleeve. Please check again, maybe there are two options, but the factory only uses the 390 sleeves from Mahle for their rebuilds.

We have developed a coating for US style pistons and have three data points of which one has failed and two are successful.

We have one block being built using the US Chrome process...no ETA yet.

Good luck with your efforts.

Marc
DEVEK