QUOTE(RFoulds @ Mar 19 2019, 03:16 PM)
To race in VARA D Production 2 liter class, I want to build a solid reliable motor. I am limited to the stock crank (71mm stroke), and stock piston size (94mm)
I have on hand a GA short block and a NOS set of Mahle 94mm P&C's, 8:1cr. I also have a nice pair of Italian Weber 40's. So my thought is, with the right machining and balancing, I should be able to build a solid reliable 2.0, that can produce 120hp . (wild guess)
Of course, what version of Webcam to use is still TBD, and heads.
questions I have:
am I kidding myself that the stock Mahle cylinders can handle continuous high rev's and heat?
will 44IDF carbs be significantly better than 40 or will the size of the jets matter most?
besides balancing crank, rods and flywheel, what machining should I consider? (Have not considered the heads yet.)
Okay, here are the cliff notes on my engine built by AJRS.
94/71 Bore Stroke
"Euro" pistons
Webcam 86B
"Welded" heads 38/48
Balanced rockers - polished, etc
Swivel feet
Dual spring
Wedge Crank
Lightened Flywheel
Straight Cut Cam gears
Electromotive crank fired ignition
Half shaft driven alternator
Electric downdraft fan (there are no belts on this engine)
Weber IDF 44's (still working out jetting for sea level)
I am / will fill in details as I sort the jetting and dig through the stack of receipts from it's build. I'd provide cost numbers, but it was all done 15+ years ago so they will be way low.
In my conversations with the builder and other research the common theme with the T4's is headwork is where the horsepower is. Get it to breathe and it'll reward you well.
This is / was not a cheap engine, but boy howdy it pulls like a tractor. The S and X gears make it a very close ratio box that tops out at 120 or so, but if you don't mind shifting, there's a gear for pretty much any situation. Redline is at 6k. You can wring it out more but there's not really any power above that. Being a 914 you can shift mid-turn without consequence. If you're coming from a 911 (like me) this is a massive bonus. It's a big go kart. Dive into the turns, modulate throttle until it hooks up and then mash it. Huge fun.
-C