The only draw back is $2500 minimum in costs for twin plugs. The advantage? You gain 10 hp. in both the 9.8 or the 10.3 version. Maybe a bit more on the 10.3 say 10/15 hp and durability of course with our pump gas.

The issue for me, while I am putting mine back together, is the cost verses performance gain.

The Max Moritz pistons were designed specifically for single plugs and an improvement in combustion chamber and burn front for CIS and Motronic. That improvement alone is a fairly big deal in my book. I suspect most haven't realized that part of the improvement.

So on the same line of thinking of defogging the myth or mis-information( :D ), one could trade 5 hp for reliability in a 9.8CR twin plug SS3.2 -vs- a 10.3CR SS3.2, agree?

I thought a dual plug Electromotive setup could be had for much less than 2500 bones...or were you thinking the dual set up with distributors?

I like this thread :D

Just to further clarify, the picture Wayne posted is my piston, from the other thread. It is 98mm, 22mm wrist pin, 37.3CC dome volume, 10.x:1 RSR piston to make a short stroke 3.2 from a 78-83 911SC engine. The label on the box is in German, but I can probably take a picture if anyone is interested.

From memory, the 964 based twin plug conversion cost me ~$1500 ± $100. Certainly under $2000.

Tom

As always my current quotes on getting anything done locally (in Oregon and Washington) are a good deal more than what some others seem to get by on ;)

$2000 for electromotive twin plug installed (1500 in parts) and $500 for the machine work. 964 TP from Weiner and RSR TP from Andial were a good deal more.

My take is published compression figures from Mahle are not always as high as stated. I would check compression on the rebuild and decide what best suits your setup and pocket book.

When it comes to a rebuild any number of things can be done. Money no object, it would be easy to say yes to everything. The decision is yours as a smart consumer on what should actually be done on your project.

In my case I suspect I will stick to Max Moritz's original engineering for the CIS and do a 9.8:1, single plug. Depending of course where my actual compression comes in at on my case, P&Cs.

This is one of my Mahle, 98mm, 9.8:1 Max Moritz pistons (these are for a 74.4 crank and 23mm wrist pins) with ceramic coating on top and moly dry film lub on the skirts.

http://www.standingwave.org/albums/p.../ahl.sized.jpg

Could anyone tell me if the following options are realistic for a healthy 3.0?

98 MM pistons and cylinders with 9.8:1 cost $3700 and increase HP by 25 - 30.

95 MM JE pistons (using stock cylinders) with 9.5:1 cost $1000 and increase HP by 15 - 20.

What is the maximum street c.r. with 94 octane and single plug?

What is the maximum street c.r. with 91 octane and single plug?

I think you should expect the low side of your numbers 25 or less @ 12% on your 98s and less @ 10 HP increase on the 9.5s depending on your current compression ratio. If you are already at 9.8:1 you won't get anything and might loose some. At 8.5 you'll get the 10hp. increase. 9.8/10.3 for 94 octane and 9.5/9.8 or a bit less for 92 octane.

Remember that either higher octane or twin plugs are the ways to keep your engine in one piece.

rdane, is "your" Mahle list available online? I couldn't find any information (specs & model number) for old Mahle P's & C's online.

Thanks

Greg, I am not sure, but some of it is/was on the Andial web site.

Noahs' car seems to have been unique. He was running a lighter crank than a normal 3.0 but I also suspect his dyno numbers were more than a bit optimistic.

My understanding is Noah's car was totaled, so we won't be able to make any further comparisons. May be Noah can add more to that comment.

I have the dyno numbers from over a dozen 3.0s now with different mods including 9.8 compression and have yet to see any that have bested my late 3.0 with 183 at the rear wheels by more than a couple of HP. Nothing even close to a 20 HP jump. Half of them have been on the same dyno and same day. The stock 3.2s weren't running 200+ at the wheels BTW but where also well under 200.

I had duplicated Noah's engine with SSIs, 20/21 cams and a sport muffler on my '79. I didn't have a Carrera crank or the higher compression. Neither of those mods or a combination of the above would typically give you another 20hp at the wheels.

The majority of SCs of any year run between 165 and 175 rwhp with SSIs or an early exhaust. Anything over 175 rwhp is exceptional.

Noah was quoting 204 at the rear wheels, which is a big jump. 1. (one full point) in compression seems to add 10 hp instead of 10% to a 3.0 is the general consensus from the engine builders I have talked to.

My car ended up with 215 at the crank, Noah's was a claimed 240 at the crank.

Funny part is on the track and on the street my car was indeed a bit more than a stock SC but not that much more. And my car is 2300# with a short gear box! No way it was 20% better than a stock SC which is typically 200hp at the crank.

Re: Quick FAQ 3.0/3.2 upgrades to 3.2/3.4
 

OK, so could I fit turbo P&C's to a 3.0SC and essentially get a turbo long block? I realize the cams and heads are different but it's a thought. I had considered just installing custom low compression JE pistons but just checked my engine and found it has Alusil cylinders. At this point it seems my best bet would just to buy a 3.0 or 3.3 long block but they're not often available so I'm checking options.

Noah's car bit the dust, but the engine survived. He has the Euro injection on it, so he's starting from about 200 HP (I believe) in stock form.

-Wayne

Where are you guys getting Twin Plug electromotive set ups ~$2000?

The HPX systems run around $1500 for the ignition system...

-Wayne

Dear all,

I am a newbie to this site and need some advice. I have a 1988 3.2 Carrera (Euro specs) and have just upgraded the engine with Ruf 3.4 pistons/cylinders and camshafts and performance chip. Unfortunately, Ruf had sent me a chip with 24 pins whilst my ECU takes a 28 pin chip. I am currently sorting out the problem with Ruf but this is unlikely to be resolved any time soon as Ruf does not, apparently, have any mapped 28 pin chips for the 3.4 configutation. In the meantime, my car is just about ready for collection. I need some advice on the following :-

1. Inspite of upgrades, is it safe to run the engine in using the original stock chip ?

2. How do I run the engine in ? What need I observe in terms of speed or revs..etc and more specifically, what should I NOT do during the running-in period ?

3. Any other advice during the running-in period, eg for how long, oil change…etc

4. Any good ideas on how to resolve this 24 pin/28 pin chip problem ?

Thanks for any advice.

Wayne, ok, just ignition, I thought they were talking engine management as well.

Winky, I would NOT run the engine with the stock chip. The timing may be retarded some on the RUF chip to avoid detonation if the pistons are of a higher compression ratio. You may want to reach out to Steve Wong who is a custom chip programmer. He may be able to match the programming of the 24-pin chip and program a 28-pin chip for you.

As for run in, I will defer to other experts here on the board, namely Wayne, but I would suggest keeping revs below 4500-5k for the first 500 miles and if your cruise works, DON'T use it, you don't want to maintain constant revs for any lengthy period of time. As for oil change, I would check with Wayne's book, but I believe it was a quick one using dino oil almost immediately after turning her over and running it up to operating temp, to get the metal shavings out. Then I would use a good grade dino oil for the first 1500 miles to allow the motor to break in, followed by a switch to synthetic.

Just some thoughts, but Wayne is the expert here.

Roamer,

Thanks for advice. I am ahead of you there - have been in correpondence with Steve Wong already.

Just thought I would add that my 30 to a 3.4 is up and running with a single plug...more info coming soon after I get the break in done and some dyno time.

Ok,

Now I'm thoroughly confused!! I'll be increasing my displacement from CIS 3.0 to Weber 40 carbed 3.2... Steve at Rennsport has 95mm nik pistons/cylinders at 3.2 for this setup running at 9.5:1... Was I mistaken? Or are things different when running carbs? Would the stroke issue be the same?