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-   -   3.5 Yes or No? (http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/396174-3-5-yes-no.html)

Richard Buckner 03-02-2008 09:19 PM

3.5 Yes or No?
 
I am on the verge of rebuilding my 1980 3.3 turbo. I have a set of 3.5 Mahle cylinders that are brand new. I am going with an EFI system on the engine. Here is the question. Do I go with the 3.5 cylinders? I have heard quite a few arguments against this modification, mainly boring the spigots and potential cylinder sealing problems. I do not plan on running more than 1.0 bar with a 8.1 compression ratio. So what do you think?
Thank you.

A.Wayne 03-02-2008 09:25 PM

You already have the P&C so your concern is to use or not to use. I'm not a fan of the 3.5 conversion on a 3.3 , better to go 3.4 ........Is your 3.5 from andial ?

AngM018 03-02-2008 09:39 PM

I have heard rumors of slip fit 3.5's. Can't remember who was making them though. Doing a search may bring back some results.

I personally stuck with the 3.4 upgrade. I didn't like the idea of machining the case, and once its done, there is no going back. If it was good enough for the yellowbird it is good enough for me...

935TURBO 03-02-2008 11:16 PM

Hi Richard, that's the upgrade I started....and yes, first of all, you must consider that the engine case will have to be machined carefully....as you can see here....
http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/325613-new-member-presentation-2.html

I got MAHLE 3.5/7.5/1 and 962 twin plugs heads....

930gt-40r 03-03-2008 08:48 AM

Is there a possibility of getting the spigots machined for O-rings like the 993GT2 utilizes? I would think that this would be optimal.

fredmeister 03-03-2008 01:38 PM

Is there anything wrong with machining 1mm off the outer diameter of the 3.5 barrels so that you don't need to machine the case?
It should not weaken the barrels anymore than the 3.4 since it is only 0.5mm on the radius or wall thickness....at least it seems negligible.
Just a thought.

935TURBO 03-03-2008 02:30 PM

Quote:

Originally Posted by fredmeister (Post 3805749)
Is there anything wrong with machining 1mm off the outer diameter of the 3.5 barrels so that you don't need to machine the case?
It should not weaken the barrels anymore than the 3.4 since it is only 0.5mm on the radius or wall thickness....at least it seems negligible.
Just a thought.


Don't know if it's a better solution....?......


http://img181.imageshack.us/img181/6...520135mfp7.jpg

http://img404.imageshack.us/img404/6...520127mus7.jpg

http://img181.imageshack.us/img181/3...110012mvi2.jpg

Richard Buckner 03-03-2008 05:39 PM

Quote:

Originally Posted by A.Wayne (Post 3804413)
You already have the P&C so your concern is to use or not to use. I'm not a fan of the 3.5 conversion on a 3.3 , better to go 3.4 ........Is your 3.5 from andial ?

Wayne,
At this point I only have the cylinders. I am going to have a set of pistons made. I purchased the cylinders and they came with 11.5 to 1 Cosworth pistons. I got a great deal so the pistons are extras. I do agree with you on the 3.4 prefrence. I just hate to spend the extra money on 3.4's when I already have the 100mm.

A.Wayne 03-03-2008 06:34 PM

If you are going to have pistons made , then i would go back to cosworth for a lower comp version.

les_garten 03-03-2008 07:11 PM

Quote:

Originally Posted by Richard Buckner (Post 3806262)
Wayne,
At this point I only have the cylinders. I am going to have a set of pistons made. I purchased the cylinders and they came with 11.5 to 1 Cosworth pistons. I got a great deal so the pistons are extras. I do agree with you on the 3.4 prefrence. I just hate to spend the extra money on 3.4's when I already have the 100mm.

How about selling the cylinders?

Les

Richard Buckner 03-04-2008 06:33 PM

Quote:

Originally Posted by A.Wayne (Post 3806400)
If you are going to have pistons made , then i would go back to cosworth for a lower comp version.

Why Cosworth and not JE?

Richard Buckner 03-04-2008 06:35 PM

Are you interseted in the cylinders?


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