long block question

[mvand5]

does anyone know the answer for this. what is the difference between an n/a block versus turbo block and can i use a turbo block, long block, heads and all, in a n/a 944? i need a motor and found a sweet turbo long block deal and wonder if it will work ok if i dont run a turbo.

[9FF]

Pistons are different, you will have to fit your na pistons in the turbo block. The cam may also be different depending on year. There are a few other differences but they won't affect na operation.

Other minor differences might be oil level sender, AOS, flywheel/clutch/housing, coolant elbow, knock sensor. Again just swap out to na stuff from your existing na block, disregard knock & oil level (if your year doesn't have it).

[mvand5]

the turbo is a long block, just no accessories, so i can swap my stuff onto it and it will work without changing internals? minus not hooking up what i dont have?

[Pete R]

The turbo has lower compression in anticipation that boost will be added. It will probably work but you may not be happy with the results power wise

[mvand5]

well, it is an option then i just convert to a turbo and have the big stuff i need already. thanks for all the advise

[Rasta Monsta]

Be aware that 2.5 blocks come in several "tolerance groups," therefore your NA pistons might not be the correct fit for that block if you decide to go that route.

[9FF]

Be aware that 2.5 blocks come in several "tolerance groups," therefore your NA pistons might not be the correct fit for that block if you decide to go that route.

There is some overlap in the tolerance groups plus you can coat the piston skirts to bring them to spec. Plus don't forget those groups were for new engines and not engines with wear like most of ours.

[John_AZ]

Originally Posted by Rasta Monsta

Be aware that 2.5 blocks come in several "tolerance groups," therefore your NA pistons might not be the correct fit for that block if you decide to go that route.

Listen to Rasta.
(and the recent post on brakes and sway bars)

FYI and move down on the link:

944 Online Forum - The Porsche 944 Forum For The 944 Enthusiast.

John

[mvand5]

i guess i didnt specify but i meant long block, not just block. but someone mentioned compression therefore horsepower loss so maybe i keep looking. i popped a piston thru the old one so a long block or more is what i am looking at now

[Rasta Monsta]

We were thinking piston swap because a 951 motor without a turbo would be lucky to make 100 HP.

[Pete R]

The turbo's only 8 to 1 comp. I imagine depending on the year a NA would be over 9.5 to 1. I don't know how much of that was done with the head but a lot of it was probably done with the piston. But if the block is good, you could probably get a new/used set of NA pistons and have a nice motor.

[Cocacolakidd]

Doubt seriously if the block is any good when a piston goes through it -

If you have a good deal on the Turbo Long Block why not go turbo all of the way. There are allot of good used Turbo parts around now days, and being as you are in for a big job any way add all of the turbo and stuff (DME,KLR, Turbo, Exhaust, etc.)

[HondaDustR]

Originally Posted by 9FF

There is some overlap in the tolerance groups plus you can coat the piston skirts to bring them to spec. Plus don't forget those groups were for new engines and not engines with wear like most of ours.

Can't coat pistons that are a larger tolerance group than the bores. Plus, it could get ugly if "worn" bores and pistons aren't measured for taper and out of round to determine that the clearances won't get too tight on the less worn areas of the bores/pistons, esp on a higher heat application such as forced induction. The variances are small, but I would still be careful. No use seizing a motor overlooking details.