Yet Another T Question

DavidPorter · 02-10-2003, 08:04 AM

Since the T cylinders are iron, can they be bored? If so, is it economic to buy just oversized pistons, if available? I have a 2.4 and wouldn't mind a bump in compression at the same time.

Thanks.

Wayne 962 · Wayne 962's Garage

Yes, they can be bored out. However, you need to make sure that you run the right pistons in there. Nikasil and Alusil won't work well, as they have different thermal expansion properties...

-Wayne

DavidPorter · 02-10-2003, 12:39 PM

Hey, aren't those cylinder materials, not piston materials? Or are there special pistons for the alloy cylinders that I shouldn't use with the T cylinders?

Any vendor ideas? I know the JE pistons are upwards of $1,000, which is getting pretty close to the price of a complete 2.7 P&C set.

rvanderpyl · rvanderpyl's Garage

You would be fine with JE Pistons. You can also install 2.2 pistons and gain more compression which will provide more of a power increase than the little displacement increase you would get with the .01 bore increase you can do.

The Alusil cylinders use a special iron coated piston to prevent wear at break-in.

I believe that the early motors had forged pistons in the S series and cast in the other models.

Wayne 962 · Wayne 962's Garage

There are many misconceptions with respect to Nikasil and Alusil - all of these are explained in detail in my new book. I'll cover them briefly here:

- Nikasil cylinders, coating is slight magnetic
- Nikasil cylinders can be reliably honed and reringed
- Alusil cylinders cannot be reliably reringed and/or honed. It's been done before, but many times they will fail.
- Alusil was meant as a one-time-use product
- Nikasil - hard cylinder, soft piston
- Alusil - Soft cylinder, hard piston
- You CANNOT mix and match Nikasil and Alusil components, because of the above two properties (soft/hard).

Hope this helps,

Wayne

tryan · 11:53 AM

throw them some viagra. they'll all be hard!

cast pistons and cast jugs on 72 and 73 t's only?

DavidPorter · 02-13-2003, 07:28 AM

I think I'm going with 85mm JE 9.5:1 pistons. EBS supplies the pistons and will do the 1mm overbore on an exchange basis. E cams and Webers.

tryan · 02-13-2003, 01:47 PM

sounds like a good plan! there is an old thread on the 2.4 t build but it's a favorite on the other computer. i'll re post later. has the mfi been gutted? i think some people are runnning e injection pumps on t stacks without problems?

DavidPorter · 02-13-2003, 02:39 PM

I have two engines, the original complete MFI engine with 125K, at least two burned valves, lots of oil leaks, and an injection pump that needs work, and a '73.5 long block. The plan is to use the later engine, which is supposed to have around 80K, with carbs and better cams.

I haven't been able to determine whether the T and E intakes/throttle bodies are the same. The port sizes are the same, so it would be logical I suppose. For now I'm going to put the MFI engine in the corner.

tryan · 02-13-2003, 03:02 PM

hope nobody took offence to the viagra thing. i get spamed with so many emails on it that i would need to put my desk in the next room

an aol thing.

i had trouble trying to figure the stacks out, i believe there are three sizes accourding to the eurometrics price sheet. there are some threads on earlys that discuss it also

here is the link to the other build the 2.4 t thread. it's interesting.

clean and fill the mfi pump for storage

jim72911t · 02-17-2003, 07:43 PM

Hi David,

I am the one who posted the original thread that Tryan referred to. Sounds like you are at about the same point in your rebuild as I am.

I'm torn between using the 85mm JE pistons or trying to find a good used set of 2.2E or S P&C's.
I had a line on a set of 2.2T P&C's but have been told that there would not be adequate valve clearance with E cams, which I'd like to go with. I also ruled out a 2.7 conversion due to my 3R case.

Like you, I'm intersted in a modest performance boost without going overboard in the $ department. I'll try using my stock MFI but don't anticipate good results, especially if I go the JE route. If I have too many tuning problems, I'll probably go with Webers until I can get the MFI properly rebuilt and calibrated.

I'd be interested in comparing notes with you sometime on your progress. I'm at the point where it's time to write some big checks, but don't want to do so until I'm absolutely sure I'm going in the right direction.

Jim
'72 911T

jim@paulcomp.com