Drag race engine to Road course engine

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Druck1
Posts: 23
Joined: Thu Jan 01, 2015 5:04 pm

Drag race engine to Road course engine

Post by Druck1 »

A while back I bought “ pig in a poke” engine. I was really looking for the Scat 3 piece case. What I have is full on drag engine. Professionally built but never run. Dry sump 3 pcs case, 94x88, Scat flanged crank, 5.7” I beam rods, 33mm ht pistons, Total Seal rings, CI barrels. .060 deck. Cam is Crower 61007 with 1.1 rockers. Heads are 44/38 valves with very stiff double springs and little tiny chambers. I think these heads would require lots of work for my application.
I want to repurpose the engine to go into a Porsche 912, mostly for DE track use.
My plan is to source a set of twin plug Revmaster heads, (I like the throttle response and mid-range torque of twin plug) lighten up the springs as I don’t need to rev past 6800 rpm and set the CR at 10.5 or maybe 11:1. CB Performance dry sump oil pump, front oil cooler. Weber IDF44’s. Willing to trade reduced ultimate performance for hopefully some durability.
Good plan? If the Crower cam works I don’t need to do complete tear down.
Ian Godfrey
Posts: 214
Joined: Thu May 27, 2010 2:52 am

Re: Drag race engine to Road course engine

Post by Ian Godfrey »

That's not really the right cam for track use, too much duration for the revs you'd like to run at, it's an 8,000rpm drag cam! Split the case, put the right cam in, and I think you will be much happier.
Are your rockers really 1.1? that would be really weird with this cam and the valve size/springs.
I'd choose the heads, then buy a cam and rockers to match the kind of head flow you achieve. Look for lots of power under the curve not peak power.
i think the revmaster heads come with 40mm inlets.... so with a good port and chamber job and no more than a Web 86B with 1.4 rockers with the big cc's it should be a blast. I have this cam in a 2387 and it has a broad power band that tops out at about 7,000. I run it with 9.8:1.
I think you will need the clearanced version of this cam because of the 88 crank. Also if your case doesn't have a drop cam you may need the cam ground on a smaller lobe circle (which Web can do for you)
good luck and keep us posted
Druck1
Posts: 23
Joined: Thu Jan 01, 2015 5:04 pm

Re: Drag race engine to Road course engine

Post by Druck1 »

I appreciate the input.
I have switched to Mofoco 050 heads. Roy has been helpful, and they are good heads with options and features needed.
This seems to be a really well built drag engine. I am sure it’s a drop cam. Nothing on Crower cam card indicates reduced base circle. The card does say 1.1 rockers
Will look into the Web 86b
Ian Godfrey
Posts: 214
Joined: Thu May 27, 2010 2:52 am

Re: Drag race engine to Road course engine

Post by Ian Godfrey »

Those heads would be a good fit for your engine and intended purpose, great cooling and a fairly conservative design, and that's good about the dropped cam. Yes, for some reason the crower specs always refer to 1.1 rockers, but to make that cam work properly you need a lot more lift. With a bit of luck you may have some ratio rockers on your engine.
Anyway, if you look at the 86B with say 1.4 rockers, consider CB 650 valve springs as they are much easier to set up with a decent distance to coil bind (long life) than most other dual springs. They are also VW outer diameter.
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