 7R cases ?, what's so special? |
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| DougC |
 Jan 13 2005, 09:45 AM
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#1
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Senior Member  Group: Members Posts: 949 Joined: 6-July 04 From: Dallas, TX Member No.: 2,307  |
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 |
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| brant |
Jan 13 2005, 09:49 AM
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#2
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914 Wizard Group: Members Posts: 11,641 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains 
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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.
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| lapuwali |
Jan 13 2005, 10:05 AM
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#3
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Not another one! Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743  |
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.
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| xitspd |
Jan 13 2005, 10:49 AM
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#4
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Technology and Tradition 3.6 and 914-6 Group: Members Posts: 1,305 Joined: 17-November 04 From: Foothills of Mt. San Jacinto, CA Member No.: 3,136 |
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.
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| michel richard |
Jan 13 2005, 11:06 AM
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#5
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Senior Member Group: Members Posts: 1,291 Joined: 22-July 03 From: Longueuil, Québec Member No.: 936 |
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) |
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| michel richard |
Jan 13 2005, 11:08 AM
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#6
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Senior Member Group: Members Posts: 1,291 Joined: 22-July 03 From: Longueuil, Québec Member No.: 936 |
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 |
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| sixnotfour |
Jan 13 2005, 11:14 AM
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#7
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914 Wizard Group: Members Posts: 10,437 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains
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(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif)
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. (IMG:http://www.914world.com/bbs2/html/emoticons/burnout.gif) |
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| Root_Werks |
Jan 13 2005, 11:25 AM
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#8
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Village Idiot Group: Members Posts: 8,338 Joined: 25-May 04 From: About 5NM from Canada Member No.: 2,105 Region Association: Pacific Northwest
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Jeff, is my 2.2 a 3R case then? Like I care, just curious. (IMG:http://www.914world.com/bbs2/html/emoticons/idea.gif) I spin mine 7500rpm stock no matter what case it has. Doesn't do much up there, but sure sounds cool. (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif) |
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| sixnotfour |
Jan 13 2005, 11:36 AM
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#9
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914 Wizard Group: Members Posts: 10,437 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains
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Dan,
It will eventually crack by the # 1 main Bearing at that speed, Or by your personal six history it will spin a bearing. (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif) Not worry Dan I got more.... 4-5R close to 7R (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) |
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| Root_Werks |
Jan 13 2005, 11:40 AM
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#10
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Village Idiot Group: Members Posts: 8,338 Joined: 25-May 04 From: About 5NM from Canada Member No.: 2,105 Region Association: Pacific Northwest
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(IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif) Oh yeah, isn't there still one of my "destructions" sitting somewhere around your shop? (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif) |
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| lapuwali |
Jan 13 2005, 12:23 PM
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#11
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Not another one! Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743 |
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.
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