1966 ford 427 le mans race engine simulation dyno numbers

[vector1]

alright here are the numbers used and the power figures since there was lots of conversation on the 429/460 site. thought all of you might find this of interest, it is from eap computer simulation program of course. i'll try to make it readable.

4.24 bore x 3.78 stroke, 426.98cid

2.09" intake, 1.625 exhaust

compression 12.5 chamber volume 76.1

dual plane manifold, 1 780 cfm carb.

headers with open exhaust

solid flat camshaft intake 244 102 c/l, exhaust 244 102c/l, lash .025 both, rocker arm ratio 1.76, lobe seperation 102, gross valve lift .5 both,

primary exhaust pipe dia. 2.15", collector length 25"

pk tq 512 @ 5000, pk hp 510 @ 5500, avg tq 449, avg hp 364

10.8" idle vacuum

[patrickt]

If you do nothing but back the compression back down to the 10.25 that he said the engine has, what does that do to the numbers?

[vector1]

Originally Posted by patrickt

If you do nothing but back the compression back down to the 10.25 that he said the engine has, what does that do to the numbers?

pk tq 489 @ 5000, pk hp 486 @ 5500 avg tq 428, avg hp 346

idle vacuum 8.3"

btw, both graphs climb real good to 3000rpms then dip real bad to 3500 and start climbing again.

[patrickt]

Originally Posted by vector1

pk tq 489 @ 5000, pk hp 486 @ 5500 avg tq 428, avg hp 346

idle vacuum 8.3"

btw, both graphs climb real good to 3000rpms then dip real bad to 3500 and start climbing again.

... and if you now run some mufflers, even the more forgiving ones? But not straight zoomies, it's got to be something realistic.

[elmariachi]

Keep going and you'll be down to my idle vacuum. And don't forget the bump for the super race gas.

[patrickt]

Originally Posted by elmariachi

Keep going and you'll be down to my idle vacuum.

That's interesting. I pull over 13" at 850RPM. My cam is 245/245 @ .050.

[elmariachi]

Well I was being a bit tongue-in-cheek (which can get you hurt around here.) It was about 7" when we had it backed down to 16* initial. At 20* initial, where Don Gould wanted it, 13". I am back to 18* initial because I couldn't get what I thought was the right curve using the MSD springs at 20* and its about 10" @ 900 rpm idle. 248/248 @ .050.

[patrickt]

Originally Posted by elmariachi

Well I was being a bit tongue-in-cheek (which can get you hurt around here.) It was about 7" when we had it backed down to 16* initial. At 20* initial, where Don Gould wanted it, 13". I am back to 18* initial because I couldn't get what I thought was the right curve using the MSD springs at 20* and its about 10" @ 900 rpm idle. 248/248 @ .050.

I think your LSA is skinnier than mine, too. At 114 degrees for a LSA, my overlap is less, more vac, but it shaves off some of the overall power.

[Gunner]

Needs mufflers, air cleaner, water pump and alternator to be an apples-to-apples sim. Fan, too, for 60s tech. (When did electric fans become common?)

[elmariachi]

You:



Me:

[patrickt]

294 seems awfully short for seat-to-seat. Are you sure that number isn't at a different number, like .01 or something?

[elmariachi]

Originally Posted by patrickt

294 seems awfully short for seat-to-seat. Are you sure that number isn't at a different number, like .01 or something?

Wrong settings, fixed it.

[patrickt]

Originally Posted by elmariachi

Wrong settings, fixed it.

My overlap at .050 is only 17 degrees. It is 96 degrees at seat-to-seat.

[elmariachi]

Originally Posted by patrickt

My overlap at .050 is only 17 degrees. It is 96 degrees at seat-to-seat.

Mine at .050 is 28*.

[patrickt]

Originally Posted by elmariachi

Mine at .050 is 28*.

Yes, your four degrees, at the cam, less of lobe separation is pretty significant. The lobe durations are effectively the same, but you have a higher performance cam than mine. The next step up, back in the day, was the cam that DCDoug has (the "B" cam). As I recall, the LSA on that was 106 but still the same lift and duration that I have.

[elmariachi]

Originally Posted by patrickt

The next step up, back in the day, was the cam that DCDoug has (the "B" cam). As I recall, the LSA on that was 106.

Do you recall what the lift was on that B cam?

[patrickt]

Originally Posted by elmariachi

Do you recall what the lift was on that B cam?

Exactly the same as mine, same duration, same lift, but the LSA was moved down to 106.

[elmariachi]

I had thought about that cam, but after talking to Keith and telling him I would likely move up to aluminum heads and the 2x4 at some not-too-distant point, he suggested the 294S. It idles good, and revs and pulls like dammit.

[patrickt]

Originally Posted by elmariachi

I had thought about that cam...

Same here, but I thought the "B" would be a little more of a PITA on the street, although Doug swears he loves his. It's "8 toes out of 10" in to race mode.

EDIT - BTW, the Ford literature specs it as making its best power between 6000 and 7000 RPM.

[elmariachi]

Originally Posted by patrickt

Same here, but I thought the "B" would be a little more of a PITA on the street, although Doug swears he loves his. It's "8 toes out of 10" in to race mode.

EDIT - BTW, the Ford literature specs it as making its best power between 6000 and 7000 RPM.

I can imagine the B is a gnarly cam. I am still being gentle on my engine, I think I have only been to the 6200 rev limiter 2 or 3 times, but the power from 4500-6200 in 3rd into 4th is what David Crosby calls "celestial."