Well then I think you may have worded your first post in a way that had us all worried. What type of sleeves is he using, I am assuming dry? And have you looked for an undamaged block and compared prices to boring and sleeving?

 

Im gona have to talk to me dad... What we were going to do is look at the pistons and see if we should reuse them. If they are in bad condiction we were going to get JE's. After reading all this so far I guess we should go over sized so a 2.7 (100.5). I will talk it over with my dad and see wht he has to say.

-Ian

 

100.5 mm won't get you far. That's first oversize.
bngt

 

TurboX,

Just be sure to get some kind of warranty on the motor -- 1 yr, 12k, etc. The stock 944 turbo bore is 100 mm. When the cylinders are scored, the official cure it to bore it to 100.5 and use over-sized pistons. There is a special boring machine to do these motors, which many machine shops don't have. It is not uncommon or illogical for a machine shop to suggest moving to sleeves and JE pistons if the bores are scored. It is difficult and expensive to find the correct size piston (100.5) for a re-bored stock block. Because 100.5 pistons are hard to find (and/or because some machine shops are are not equipped to work on Alusil blocks), machine shops will suggest sleeves. The sleeves cost more than boring, but the cost is offset with cheap easy-to-get JE pistons. Once you decide to sleeve it, however, there is almost no incremental costs to move to 104mm pistons, which gives you a bit more displacement (2.7 liters vs. 2.5). If you'd rather stay with stock bores at 100.5, there are now a few non-Porsche piston options out there. John at Vitesse hooked me up with a supplier now selling pistons for the Alusil bores, and Mahle USA now has some options. I can supply contact info if helpful.

 

Those two sentences may well be mutually exclusive... While it's possible this is what your mechanic is telling you, it's not entirely clear here... So... Just so YOU know, the fact that the block is alusil has nothing to do with how much you can bore... beyond the structural properties (wall thickness) of the block design itself.

In otherwords, alusil isn't a coating that one can "drill" past. It's a homogenous alloy. It's the paste/hone finishing of the freshly exposed surface that leaves the silicon "proud" and provides a hard finish... no matter how thin or thick it's been "sliced"...

 

I was mistaken, (dar) my father has been doing all the talking to the mechnic and he maid it confusing to me. He called the mechanic today and talked to him some more. Sleeves are only a couple hundered $ not 900. He has sleeved 944 and 951 motors before so he obviously has some idea of what he is doing. Why would i spend the money on a new crank i am trying to save money. We are trying to get this motor running not trying to turn it into a race motor. If we stay at 100 we can use the stock pistons so we do not have to spend the money on new OEM pistons or get JE pistons.

If we did go with over sized pistons (104) we would have to get the 3.0 crank to get the 2.7 liter. The pistons take almost a month to be maid plus they have to find/make the rings which take a while to do.

Sleeving the motor to stock size will be a little bit more exspencive than honing it out but we will save all the money from not having to buy new pistons and in the 2.7 liter case a new crank.

-Ian

 

There is no need to use a 3 liter crank to get to 2.7 liters. You just need 104 sleeves and pistons. JE can source the pistons and rings quickly, as can Weisco and a host of others. In the event your stock pistons are worn beyond limits, the bigger motor would add nothing to the cost of your rebuild.

 

JE takes about 3-5 weeks to make the pistons. IF the pistons are worn beyond limits then it is a high probablity we will get over sized pistons.

 

Or bore and sleeve to 106 mm, pistons will be in stock on the shelf.

4" big block stuff

 

haha cool.. thats another option but i mean we have to see how the pistons are first... if they are alright well... back in the motor they go

-Ian

also if i wanted to make my car into a race car i would add some flame vinyl around the wheels, put a 4 and a half inch tip on it and put a spoiler on the rear...JEEZ

 

It's just that more displacement is such a lure for so many of us, it is painful to think of you foregoing the extra cc's to save $600 or so (since it normally costs many thousands to get done). But, I understand the need to contain costs. Things can get out of hand fast otherwise... Either way, I hope your motor works out and you are back on the road soon!

 

Turbo X,

Be careful here. I do not think you can run the stock Pistons with a Ductile Iron sleeve. If the Piston Bores are scored, then you have 2 choices if you want to use the same block. Sleeve or oversize the stock Bore. You have to be careful if you choose to repair the stock bore. Often you have to go more that 1st over to clean up the bores. BTW, if the machine shop does sleeve work, they will have vertical boring bars and honing equipment. Its the special pads and paste they may not have for the vertical honing machine, normally a CK10 or later machine. If they don't expect them to refuse or charge you for these parts. Sleeving and the cost of the sleeves will cost you at least $ 1000.00 if done properly. You need to use flanged sleeves only. By the time you bore the block, fit the sleeves, bore the sleeves and hone them to size, deck the block surface, and pay for the sleeves, youv'e spent $ 1000.00 or more. I would look for another block first. Even a 944NA block will work. You will just have to drill for the Turbo Oil feed. You will save lots of dollars this way. Sleeving to stock bore sizes should be done only if no donor blocks are available. Sleeving to an oversize bore makes more sense, but will cost. Look around for a donor block first. Email me and I will give you some suggestions as to where to buy one and what to look for.

 

Turbo X, Listen to M42Racer he presented very valid points.. The least expensive, safest and most proven approach is to find a used block. Very few machinists had good luck sleeving the 951. Sleeving is not difficult however few simple and important steps must be taken to make sure it will live..

If you decide to sleeve the block, go to a 104mm or 106mm, when used with the stock 2.5l crank you get 2.7l or 2.8l. The extra displacement is free HP/TQ..
If you are concerned about the availability of the pistons, I have a set of each. My projects are few months away, if you are in a hurry you can have them.
Take a step back, rethink/research all of your options then proceed. Do not rush an engine rebuild, do it correctly the first time as it always takes longer and costs more the second round.

edit: If you go to 104 or 106mm bore size, you will have to use a MLS gasket (the only available option for such bores for 2.5L block). If your cyl. head is O-ringed, then you have a problem as MLS should not be used with O-ring..

 

See, we are trying to keep this project to a budget minimum. sleeveing the motor in this case is cheap than buying a used block. Its only a couple hundered $ compaired to the price of a new block. He knows what he is doing, this shop is not your every day honda tune up shop. He does nothing but build race motors and not very often does he do just "fix up " jobs like this one. He has many brand new machines (boreing) that he showed us when we went there. I am pretty sure he knows what he is doing and sleeveing should not be a problem.

As for going over sized again, im only 16 and not looking to turn this into a real track car besides PCA DE days. Once again if our stock pistons are damaged then over sizing will become a very likly option but we would rather save the money with staying with the stock pistons.

Sleeving won't be the Safest method but it is the cheepest and im not afraid of our mechnic messing up. As to finding a new block, our mechnic has had our motor for over a month now and i BELIVE he has already put the new bearings and what not in it.

Also we are putting in a thin wall sleeve if thats any different from another type of sleeve.

 

"Sleeving won't be the Safest method but it is the cheepest and im not afraid of our mechnic messing up. As to finding a new block, our mechnic has had our motor for over a month now and i BELIVE he has already put the new bearings and what not in it. "

Boy, if this statement doesn't tell a story.

Either you are not explaining what you are doing fully, or you are real big trouble. Your mechanic fitted new bearings before he realized you needed block repair. If the repair of the block will cost only a couple of hundred dollars, he is either giving you way way below cost work, or he has no idea what he is about to do. This work along with the Liners is well over $ 1000.00. closer to $ 2000.00. I hope for your sake, you are misinformed and do not know the whole story. A good used block is somewhere around $ 500- 800.00 probably.

Just thinking about it, removing the Headstuds will cost you $ 200.00.