 2 ltr from 1.7 ltr motor |
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| jb57tub |
 May 13 2019, 08:26 PM
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#1
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jb57tub  Group: Members Posts: 23 Joined: 9-January 19 From: Corpus Christi, Tx Member No.: 22,790 Region Association: Southwest Region  |
What machine work needs to be done on an early 1.7 case to convert it to a stock 2 ltr motor? thanks for any help, Jon
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| Cupomeat |
May 13 2019, 08:31 PM
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missing my NY 914 in VA Group: Members Posts: 1,336 Joined: 26-November 07 From: Oakton VA Member No.: 8,376 Region Association: MidAtlantic Region |
QUOTE(jb57tub @ May 13 2019, 10:26 PM)  What machine work needs to be done on an early 1.7 case to convert it to a stock 2 ltr motor? thanks for any help, Jon Well, I am not sure what they make any more, but they used to make slip in 96MM cyl. for a 1.7l case. The crank, and rods should need no machining as they sacrificed journal size to get the additional stroke. So, depending on what you get for Cyl, you would need to machine the case to have the cyle fit in and that is it. The heads would need machining as well, but you didn't ask about that, so I figured you have that covered! Good luck, welcome and I hope that helped. |
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| mepstein |
May 13 2019, 08:32 PM
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#3
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914-6 GT in waiting Group: Members Posts: 19,316 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region 
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None
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| porschetub |
May 13 2019, 09:55 PM
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#4
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Advanced Member Group: Members Posts: 4,706 Joined: 25-July 15 From: New Zealand Member No.: 18,995 Region Association: None |
The 2.0 914 was achieved by using the old time procedure of off-set grinding to increase stroke with a 66mm crank to 71mm,the big end journal was reduced in diameter in the process ,and then with an increase of 1mm in the bore made under 2000cc .
I understand this development was done by Porsche engineering genius Hans Mezger (RIP) which would have been a "walk in the park for him "considering the amazing race engines he designed. I honestly don't now the benefits of doing this conversion because I've never done it,some say a big bore 66mm crank motor is better as it revs easily in our (light) cars. Engine builders please chime in,rant over (IMG:style_emoticons/default/beerchug.gif) |
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| BeatNavy |
May 14 2019, 05:11 AM
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#5
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region
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QUOTE(mepstein @ May 13 2019, 10:32 PM) None (IMG:style_emoticons/default/agree.gif) Short answer is none. And 1.7 case apparently has some more desirable properties in terms of structure and durability. I just did a 2056 out of a 1.7 case. Longer answer is - it is still a good idea to get your case checked for bore alignment and ensure the registers (holes for the cylinders) match within .002" of each other. So it's still a good idea to have access to a machine shop nearby that knows these engines. |
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| 914_teener |
May 14 2019, 08:30 AM
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#6
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914 Guru Group: Members Posts: 5,205 Joined: 31-August 08 From: So. Cal Member No.: 9,489 Region Association: Southern California |
QUOTE(porschetub @ May 13 2019, 08:55 PM) The 2.0 914 was achieved by using the old time procedure of off-set grinding to increase stroke with a 66mm crank to 71mm,the big end journal was reduced in diameter in the process ,and then with an increase of 1mm in the bore made under 2000cc . I understand this development was done by Porsche engineering genius Hans Mezger (RIP) which would have been a "walk in the park for him "considering the amazing race engines he designed. I honestly don't now the benefits of doing this conversion because I've never done it,some say a big bore 66mm crank motor is better as it revs easily in our (light) cars. Engine builders please chime in,rant over (IMG:style_emoticons/default/beerchug.gif) I think the shorter stroke set up right is more fun to drive. I.ve driven both. That means a 1911. |
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| dr914@autoatlanta.com |
May 14 2019, 08:36 AM
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#7
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914 Guru Group: Members Posts: 7,898 Joined: 3-January 07 From: atlanta georgia Member No.: 7,418 Region Association: None |
seems to me I remember that there is a bit more relief in the 2.0 case where the piston skirts fit, and we had some problem years ago with the 2.0 NPR piston skirts interfering with the 1.7 case, yet the stock mahle 2.0 pistons fit the 2.0 case just fine.
Only a memory so do not quote me on this one. QUOTE(jb57tub @ May 13 2019, 07:26 PM) What machine work needs to be done on an early 1.7 case to convert it to a stock 2 ltr motor? thanks for any help, Jon |
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| Tbrown4x4 |
May 14 2019, 09:26 AM
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#8
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Senior Member Group: Members Posts: 705 Joined: 13-May 14 From: Port Orchard, WA Member No.: 17,338 Region Association: None
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I believe the thinking behind using the 1.7L case is that the 1.7 case is less stressed and therefore less likely to be damaged or need a lot of machining to be usable.
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| mepstein |
May 14 2019, 09:30 AM
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#9
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914-6 GT in waiting Group: Members Posts: 19,316 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region
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QUOTE(Tbrown4x4 @ May 14 2019, 11:26 AM) I believe the thinking behind using the 1.7L case is that the 1.7 case is less stressed and therefore less likely to be damaged or need a lot of machining to be usable. Jake Raby has also mentioned they had better metallurgy and he uses them to build his big hp engines. |
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| Mikey914 |
May 14 2019, 02:25 PM
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#10
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The rubber man Group: Members Posts: 12,678 Joined: 27-December 04 From: Hillsboro, OR Member No.: 3,348 Region Association: None
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I have a 72 1.7 that's now a 1911 and pulls just like a 2.0. It is noticeable.
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| Highland |
May 14 2019, 04:27 PM
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#11
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Senior Member Group: Members Posts: 513 Joined: 8-August 11 From: San Diego, CA Member No.: 13,418 Region Association: Southern California |
What is the 1911cc configuration often referenced on this site?
2.0 head chambers or 1.7/1.8 head chambers? Stock cam, RAT 9590, WEB cam 73? (Assuming using stock yellow injectors, D-jet) Has anyone ever built a 1.7 with relocated spark plug (to 2.0 location) or with WEB cam 73, RAT 9590 or is that displacement not large enough to gain from those improvements? |
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| BeatNavy |
May 14 2019, 04:50 PM
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#12
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region
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QUOTE(Highland @ May 14 2019, 06:27 PM) What is the 1911cc configuration often referenced on this site? 2.0 head chambers or 1.7/1.8 head chambers? Stock cam, RAT 9590, WEB cam 73? (Assuming using stock yellow injectors, D-jet) Has anyone ever built a 1.7 with relocated spark plug (to 2.0 location) or with WEB cam 73, RAT 9590 or is that displacement not large enough to gain from those improvements? Basic 1911 is 96mm P&C (slip right in, with no machining) and stock 1.7 crank (66 mm). Changes the stroke ratio so it revs up quickly. If you swap to the 2.0 crank (71 mm) you get 2056. Excellent reference: http://www.914world.com/bbs2/index.php?showtopic=141448 |
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