Dyno Results (above)

[Bort62]

More food for thought....

A.)I am extremely iterested in the 35 hp delta in performance between ported and manifold vacuum. There are two reason this makes no sense to me, and I'm not sure what that means.

1.) Ported and Manifold vacuum should be equal at WOT.
2.) Vacuum advance should be inactive at WOT because there shouldn't be any measureable vacuum.

In either (both) case, their should be no measureable difference in ignition advance between the two and as such no measureable performance difference either, providing this was the only variable. Can anyone think of a reason for this ?

When we ran ported vac, the motor stumbled and mis-fired thru the entire RPM range. I have no idea why this happened, just that it did. I wish we would have had the time to dig into it and find out what was going on, but it was early in the day and we had countless dyno runs ahead of us. Our goals were to test carbs, not figure out why the ported vac was so screwed up. In retrospect, I wish we would have tried ported on the 480cfm 4V. Would it have acted in the same manor, or disapeared? And would it have made any difference in the numbers?

C.) I find the discontinuity @ approaching peak HP interesting. Did whoever was driving the car do something odd like jump in and out of the throttle near peak HP?

I went over all the runs tonight and found something interesting. In the runs using the 200cfm-1V, the 200cfm-2V, the Holley 500-2V, and the 240/287-2V with larger jets, the dip and spike were still there, just not nearly as evident. They became more severe as power went up and as the AFR's leaned out? This is also why we tossed out the best run, thinking the peak numbers may have been in error. However, if they were not, then we were clearly over 250hp at the flywheel.

D.) Stock motor w/ Stock Autolite (I am assuming this is a Pony rebuild?) made max power @ 5650 RPM?

Two mis-typo's here. This was the new 1100 annular dicharge carb (200cfm), not a stock carb (185cfm). Also the peak was at 4650, not 5650. Sorry about that.

All this gets me pretty excited and makes me wonder what my 250ci with the fully ported head, 292 cam, and EFI will do??? Hopefully I can start putting it all together after we get back from Carlisle. The short block and head are done, I just need to install the cam, put it all together, and drop it in.

Thanks for the reply, Mike. I figured the 1bbl rpm was probably a typo, but didn't want to assume.

I think we are all pretty excited to see what a more "wild" motor will do. Mraley's combo certainly qualifies as streetable and the yet power output is pretty amazing ( ~1.25 Hp per inch is WAY good, equivilent of 320 RWHP out of a 302 ). His exact combo would make one hell of a crate motor (I'm sure you are already thinking this).

Crap, I wrote a lot more but accidentally just hit undo. Point is it sounds like we have the same questions in a lot of ways but none of them really have anything to do with the fact that the peak power made (and the corresponding torque curve) is impressive. They may have some minor issues with their dyno causing the stuff at the top - but I don't think it in any way invalidates the peak #'s as the appear to be along the line that would be drawn between the preceeding and following points.

Ported causing it to run like crap throughout the RPM range is way weird, I'll agree. I'm a proponent of manifold vacuum but I still can't find a way to justify that in my mind. Sounds like the gain in power is less from switching it to manifold vacuum than it is from just getting it OFF that particular ported source, which makes a whole lot more sense as Vac advance should be 0 @ WOT anyway.

 

[69Falcon]

His exact combo would make one hell of a crate motor

Ian, I couldn't agree more with you on this one. Mike, this hp and torque curve from this build is almost exactly what I was asking for when you ran a poll about crate motors a while back.

 

[shmoozo]

... All this gets me pretty excited and makes me wonder what my 250ci with the fully ported head, 292 cam, and EFI will do??? Hopefully I can start putting it all together after we get back from Carlisle. The short block and head are done, I just need to install the cam, put it all together, and drop it in.

Based on the astonishing results seen from Mraley's relatively "mild" build on a 200, that 250 ought to be quite a monster.

With that much cam I'm guessing it'll have some lope in its idle and a torque curve that comes on stronger as RPMs rise. Fine tuning the injection and ignition will take some time, I'm sure, but if you can get it properly optimized I have a feeling it'll make more than a few jaws drop.