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914World.com _ 914World Garage _ 7R cases ?

Posted by: DougC Jan 13 2005, 09:45 AM

I think it's probably that they were made from magnesium but is there any other advantages and would that even be an advantage on a street car? Also, are they more prone to leak..seems like I read that somewhere?

Doug C

Posted by: brant Jan 13 2005, 09:49 AM

They had more reinforcment ribs than the earlier mag cases. (5r/3r) so are the strongest case to build a medium sized race motor from.

Posted by: lapuwali Jan 13 2005, 10:05 AM

The 7R was what they made the 2.7s from, and the very last 2.4s were also made from them. A 2.4 made with a 7R case will, as stated, be much stronger because of the extra ribbing, without being anywhere near as heavy as the later aluminum cases (Turbo and SC). Magnesium is fairly weak, and the early mag cases will flex under the load a built engine can introduce, which can lead to bearing failure, or a broken crank. Pretty much all of the mag cases will leak some.

Posted by: xitspd Jan 13 2005, 10:49 AM

The 7R is the only mag case that I would consider building a high performance motor with. I had a very hot 2.2 engine built from a 2.0 early aluminum case. No leaks with 906 cams.

Posted by: michel richard Jan 13 2005, 11:06 AM

This being said, my own personnal opinion is that you can still build a very exciting engine with some of the earlier cases. Sure a 7R is the best, but if your're building a 2.4 or less, a 7R that fits will be hard to find, and an earlier case will work. If you want to rev to 9 grand have a super high compression ratio etc . . . you may be better off building an engine with what you have now.

Michel Richard
914 2.2 E MFi

(Built on a 5R)

Posted by: michel richard Jan 13 2005, 11:08 AM

Sorry,

Meant to write:

If you want to rev to 9 grand have a super high compression ratio etc . . . find a 7R. Otherwise, you may be better off building an engine with what you have now

Cheers

Posted by: sixnotfour Jan 13 2005, 11:14 AM

IPB Image
A 2.7 7R case is going to need 500.00 of machine work to make so it wont leak and the studs will stay in and the main line is staight.
2.0 alum. case 850.00 May need layshaft ugraded. also oil squiters, bore cylinder holes 2.7 bigger.

2.7 7R 200.00 machine work 500.00
The Mag cases are good if you make sure every part is flat, so it wont leak,Proper sealant important too. already has squirters,
comes in either bore.Has mech inj. pump mount.
IPB Image

Posted by: Root_Werks Jan 13 2005, 11:25 AM

QUOTE (sixnotfour @ Jan 13 2005, 09:14 AM)
IPB Image
A 2.7 7R case is going to need 500.00 of machine work to make so it wont leak and the studs will stay in and the main line is staight.
2.0 alum. case 850.00 May need layshaft ugraded. also oil squiters, bore cylinder holes 2.7 bigger.

2.7 7R 200.00 machine work 500.00
The Mag cases are good if you make sure every part is flat, so it wont leak,Proper sealant important too. already has squirters,
comes in either bore.Has mech inj. pump mount.
IPB Image

Jeff, is my 2.2 a 3R case then? Like I care, just curious. I spin mine 7500rpm stock no matter what case it has. Doesn't do much up there, but sure sounds cool.

Posted by: sixnotfour Jan 13 2005, 11:36 AM

Dan,
It will eventually crack by the # 1 main Bearing at that speed,
Or by your personal six history it will spin a bearing. IPB Image
Not worry Dan I got more.... 4-5R close to 7R

Posted by: Root_Werks Jan 13 2005, 11:40 AM

QUOTE (sixnotfour @ Jan 13 2005, 09:36 AM)
Or by your personal six history it will spin a bearing. IPB Image
Not worry Dan I got more.... 4-5R close to 7R

Oh yeah, isn't there still one of my "destructions" sitting somewhere around your shop?

Posted by: lapuwali Jan 13 2005, 12:23 PM

You can tell which case you have by looking at the casting number, which is under the oil return tubes. The last two digits are the important ones.