Another Successful Pelican Engine Build - My 3.0 Liter MFI Project

[Jeff Higgins]

Well, it's finally done. After a year of gathering parts, researching, decision making, and finally building, my very first 911 motor is up and running. Here it is, on the stand and ready to install in my '72 T:



Here is the rest of the car, now sporting a 3.0 liter, MFI inducted motor:





This project stands as testimony to the completeness and accuracy of Wayne's engine rebuilding book, and Pelican's engine rebuilding "super kits". I relied heavily upon both to finish this project, and found it both straightforward and enjoyable. If any of you out there are even considering this, I would highly encourage you to pursue it. If you can turn a wrench, you can build a 911 motor with Wayne's book and parts from Pelican. I did.

Anyway, my project is just a bit out of the ordinary. It's a street going 3.0 liter, not some full race RSR motor or anything. My goals were to both build a motor with a significant increase in displacement over my 2.4, and to retain MFI for induction. I also wanted an aluminum case, and readily available (cheap) parts. A 3.0 liter SC motor was the obvious place to start.

An '83 SC core motor was obtained from my friend Alex (RussianBlue here on Pelican), along with a rag tag assortment of MFI parts. With all of the rebuild parts (bearings, gaskets, sealants, etc.) arriving from Pelican, I was off and running.

The bottom end is stock save for a set of JE 9.5:1 pistons. All of the necessary machine work was handled by Monte Jarvies at Redmond European; crank polishing, rod sizing, balancing, etc.

Heads were modified by drilling the MFI injector ports in the SC heads, using a little jig Monte had made for the purpose. The intake ports were opened up to 38mm. This was done to provide a 1mm "reversion ledge" between the intake ports and the 36mm "S" throttle bodies I was going to use. Exhaust ports were left stock.

Cams are a custom grind from John Dougherty. He calls them his "GT2-102" grind, which is his GT2 grind with the lobe centers narrowed to 102 degrees (from 113). They provide .485"/.470" lift and 254/238 degrees duration @ 1mm lift. These are a very high lift, short duration grind. My goal was to provide enough lift to allow the 3.0 liter to breathe, and a shorter duration that would keep the power band below 7,000 rpm.

continued...

[Jeff Higgins]

I think I succeeded. The following dyno chart was taken from a session last Wednesday. I'm pretty pleased with the broad, flat torque curve and the way the horsepower comes on. It is not "peaky" in the least, making for a very fun, drivable car. Big thanks to John ("camgrinder" here on Pelican) for going that extra mile for me, listening to my goofy ideas, and coming up with a great cam to fit my needs.



Of particular note is the A/F ratios as shown in the lower graph. This is accomplished with an "015", or '72 911 "T" pump, with the "T" space cam still in place. Some of you have been following, and helping out with, my adventures in MFI tuning on this thread:

MFI Pump - Open Heart Surgery

Suffice to say, it does appear possible to adapt these pumps to oddball combinations like this. Thanks to everyone who had input there, and guided me along on this adventure. Figuring out the inner workings of the pump was at least as satisfying as building the motor itself. I feel like we really accomplished something useful there, with everyone adding their piece to the puzzle.

Anyway, there are a few others who I would like to thank for their help on this. Chris Nielsen for providing a lot of the little widgets needed for MFI, John Walker for providing even more such odds and ends and, even more importantly, rebuilding my crapped out 915 on a moment's notice, my sons Chris and Alex for countless hours in the garage with me, Scooter and Drago for stopping by to help when they could, Henry Schmidt for letting me bend his ear on MFI pumps and for providing a sweet custom cam drive seal, and some others I'm just sure I'm forgetting right now. I couldn't have done it without all of you guys.

[eapcpa]

HI Jeff,

Nice job, nice car.

[snbush67]

Looks great Jeff, so you are getting about 13.5 at 6500 rpm? Is that a bit lean? I thought that stoic was about 14.7, I don't know I was just wondering. Fun looking ride.

[SCrescue]

Very nice Jeff....now enjoy it!

snbush67,
14.7 is considered the standard for volumetric efficiency, neither lean nor rich. Jeff's engine appears to have been tuned to the rich side for more power.

Mike...

[Randy W]

Congrats Jeff!

There are benefits to being a stubborn engineer after all.

[Shearer9]

Well done that man. I am envious in the extreme