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!

Thanks for the info.

I always liked the basic Stage VI design, but the MP finishing wasn't satisfactory. Now Chapman has gotten a great set of castings to port and put things competitive. I just hope the final machined and fitted cost is not prohibitive.

Now we just need a mega block in low deck size for these heads.

Yeah, Greg...very similar. That looks thinner than what I have envisioned, what I have in mind would solidly fill the gaps between the caps and the Girdle, most likely with either tailor made steel or aluminum caps along with additional threaded holes to tie it all together. The main cap studs would wind up being way too long IMO to be effective to tie both together. You need another set of bolts to tie the girdle into the Caps.

I like that design although i would notch it out in the back to allow for main seal reatainer removal without having to autopsy the bottom end.

Jim, yeah, the only thing that sucks about the Chapmans is the price, I got them at a bit of a break compared to retail but they're still pretty expensive.

It's interesting, when I spoke to Steve I mentioned that they flow very close at all points to what the CNC ported Yates NASCAR Head flow -and that's not too shabby at all!

http://gearsandrears.com/girdle.html

there's the web site for those girdles...I have one..it's going in a 499...the object of the stud girdle is to absorb and transmit the harmonics to the block...it should prevent cap walk...I E-mailed Chapman awhile ago about the pricing..I think it was 1500 or 1600 per head...I thought that was way high until I added up what was in mine....I could have had those and been miles ahead of what I'm doing.....lesson learned...

Woodie, Thanks for the link, Spreading harmonic loads and frequencies are one of the main functions of a Girdle, providing a means of 'cross-bracing' the caps by supplementing thier alignment by using block strength is another benefit.

The girdle steel looks much thicker in the link pictures than it did in Greg's shot, that clears that up a lot. Thanks

you are most welcome....they are a sturdy piece...comes with all the hardware..if you call them..tell them Jeff from Justice with the Duster sent you...he'll add more to the bill......

Has anyone seem Dan Dvoraks 4 bolt main coversion?Says its good to 1500hp.

Gonzo440 web page

you are welcome....soon I will be sending you the mega block