Ok ,for those interested here's what Steve told me about the EM 470 motor.

As Steve had very little free time to build this motor, he had tested the Chapmans before and felt they were good enough straight out of the box ( over 750hp I guess so!).


The epoxy on the floor was to make up for a very slight mis-match to the low deck/raised port spacer. They were in fact Max Wedge ports CNC'ed into a pair of standard port (906 size) castings.

The wings I had mentioned were an optical illusion in the Mopar Muscle photograph, the ports have a near polished finished and the camera angle tricks the eye in the photo.

Steve did a lot of Tweaking on the Indy Manifold prior to the EM contest. Both of us felt that although it seems 'big', a 285cc intake port and a max wedge (1.3" x 2.6") cross section really wasn't big enough to kill the low-end torque of a 12+:1 470 inch mopar. That's encouraging to me because the choice of intakes for the Maxie port are somewhat limited. We have seen the Indy-1 310cc runner kil torque but in reality the indy has a fair amount of 'dead area' in the floor and lacks the 3/4" raised roof and floor of the Stage VI design.

At the time (early in the Chapman development) they was trying to make the MP Alcoa foundry castings seal when extensively ported, it just didn't pan out. They are notoriously porous as we on the Moparts EM team found out first hand. They wound up scrapping a ton of R&D and early production castings as they were unsellable. The Chapman castings have a slightly revised port area and are cast at the ZEUS foundry (Note: look for the ZEUS logo cast into the rocker side of the head) and they have had none of the aluminum 'sponge' traits of the Alcoas.

Steve originally broke the motor in on a Dyno with a set of Sprint car style headers and the same motor in the same tune made 780+ hp!! The TTI's on the dyno with mufflers cost him 25HP.

Another thing that Steve thought might have helped was if he had a set of super-trick Gas ported Pistons instead of essentially "Off the Shelf" slugs. In retrospect, there might have been upwards of 25HP up for grabs and other teams were running them including (IIRC), the winning Kasse motor.

Interstingly enough, Steve built his motor with good old 400 Main caps and ARP studs, I told him I would probably be going with Steel caps on the new Bullet. He had mentioned someone was working on a Girdle that tied the mains into the pan rail. I'd thought of that before (assuming it could seal the pan and have adequate clamping force to do any good), I was even working up some sketches and preliminary drawings on AutoCad of something similar.

Like I said, we talked for a long while about a ton of stuff we were both working on and were planning for future projects. I don't remember everything, it was kind of late on the east coast.

The 517 I'm planning is going to be very close to a super-sized (~10% larger) version of Steve's EM motor.

If anyone's interested, I'm planning to send one of the heads down to Dwayne, he had mentioned wanting one to evaluate for all of us @ Moparts. Happy to oblige, it might make for some interesting Tech Archive material!