The motor is being assembled as I type. I've heard figures around
360HP and 450 lb/ft.I'm thinking of using a 1" open spacer instead, and a new carb will be needed down the line anyways. Suggestions? -- Scott W. '66 Mustang HCS 289 '68 Ranchero 500 302 '69 Mustang Sportsroof 351W '97 Cougar 30th Anniv SE 4.6L ThunderSnake #57
You could easily make 450 ft/lbs, but not with those heads. They are pretty good heads for a 351. But won't flow well enough for a good
400W. IMO, the same goes for the intake. I would Edelbrock RPM heads and intake. You'll be limited to about 5,000 rpm's by air flow. But your cam will match rpm range.I built a 427W. I used Windsor Sr. heads with a stage III CNC port job. And my hydraulic roller cam is more like 290/290, .544/.544. Intake is 8 port EFI. Should make about 550hp?????? with a red line of 6,300.
If it was me I'd go with more head or less gear. Its going to make a ton of torque, but run out of breath real early. A quick computer model says 310hp @ 4500 rpm and 415ft @ 2500 rpm. A larger cam would help some, but the heads are the real killer. You may not even hit those numbers given the port volume of the heads. Going to a 800 cfm carb and a single plane intake it went to 335hp @ 4500 rpm and 420ft @ 3500 rpm. Just for grins I thru some TFS Rs on the original set up and it jumps to 355 hp @ 5000 rpm and 425 ft @
3000 rpm. With the larger carb and single plane along with the TFS-R it jumped to 405 hp @ 5000 and 445ft @ 4500 rpm.MadDAWG
"MadDAWG" wrote
Seeing as less gear will be less expensive than more head, what would you suggest? 3.25's? I have a set of 2.73's in my Ranchero but I think that woud be overkill. :)
That would be my choice. What would be ideal with that power band would be a wide ratio gear set for the tranny and 3.25 gears, but I doubt they make them for an FMX. I have a set for a C4 that gives a 2.84/1.54/1.00 ratio vs. the standard 2.40/1.46/1.00. That makes those 3.25s feel like 3.73s in first, 3.55s in second and gives the top end and cruising of 3.25s in drive. With all that low rpm torque you wouldn't have any problem with the wide gear steps.
MadDAWG
"MadDAWG" wrote
Who knows, I'm only keeping the FMX until it turns itself to shrapnel, then I'll get either a wide ratio C6 or just go for a built AOD.
But how would just the 3.25's do?
Just an FYI the AODs can be had in a wide ratio as well. :)
I would think they would be fine, but its hard for me to say what would be good by your standards. I do know that when I went from 3.27s to 3.73s in my
95gt about the only thing I noticed was more rpm at cruise. I'm sure there was a small drop in acceleration times, but it wasn't drastic change in the Levis Dynometer. Really the extra rpm and noise wasn't worth it to me, but my car is a daily driver in a big city with lots of cops. lolAlso we are basing things and a computer model which does make some assumptions in its calculations. Once you get it up and running you'll know where it runs out of breath and can base your choice from there. If you just romp around town or run 1/8 mile the 3.73s may be just fine. If you want to take day long trips or run a 1/4 mile strip then the 3.25s would probably be a better choice.
MadDAWG
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