View single post by Judson Manning
 Posted: 03-31-2006 02:29 pm
PM Quote Reply Full Topic
Judson Manning



Joined: 03-14-2005
Location: Atlanta, Georgia USA
Posts: 406
Status: 
Offline
 I can't say I'd suggest doing all that work and going the TBI route, but to each his own.

Unlike 2V american iron, 4V engines (including the dozen or so 9XXs I've built) routinely run +10:1 c/r on pump gas with no problem.  Later 912SE engines have Nikasil coated aluminum liners and came stock w/ 10.9:1 c/r. 

However, as you've pointed out:  "Can the (907) block take it?"

In stock form, the short answer is no.  Reliability beyond 160hp will eventually be a problem, but there are ways to improve the 907's bottom end.

Our crank is bigger than most V8s, but take a look at the difference between the much wider and beefier 910 bottom end vs. the 907 (exactly why it's difficult to shoe-horn one into a JH!):

http://jhppg.com/gallery/album08/P1010012

To beef-up the 907 bottom end is pretty simple: 

1.  Add dowels to keep the main bearing panel from shifting under load (the 910 uses a total of 3, the Esprit Dry-Sump Turbo used a total of 10).

2.  Cross-drill the crank.

3.  Line-bore the main saddles to use the larger OD 180^ bearings from the Chrysler 318.