how about someone running a dyno sim for a 393 for me. i just discovered how easy and inexpensive it is to build a 393. my windsor needs some more low end for my truck, so that is the plan. here is the proposed combo.
393cid,
8.5- 9.0-1 compression,
performer intake,
thermoquad carb/ 850 cfm wide open, about 300cfm on cruise,
hei distributor,
long tube headers, and a 2.5 to 3 inch dual exhaust.
cam choice of 3 comp grinds:
1- 268h dur.at .05 218, .456lift, sep 110
2- x4250H dur.05 206in, 214ex, .448 in, .483ex, sep 111
3- x4254H dur.05 210in, 218ex, .477in, 493ex, sep 111
the heads are reconditioned from aerohead
1.94 in, 1.6ex, 69cc chambers, 3 angle valve job, otherwise stock.
I know my heads are limiting, but i dont want to twist this motor very hard, 5000 rpm max, i just want great low end torque. i generally shift this thing around 3500 rpm, and it cruises in town at 1200, and on the road at 2000. these heads are a great value from a bigtime mopar head company that has started to branch out. hopefully i will make up for flow with velocity.
i am also consdiering an e85 build, the only thing i would really see changing is the compression, which i would bump to around 12-1 give or take a 1/2 point.
if you have a better cam recommendation i am open, but i am partial to comp and crower. thank you. Dan
PS how is that for number 1500?
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I ´d go with a comp cam extreme energy, and a higher cr.... 9.5
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Your probably going to wind up slightly higher CR than you think if you use flat top 302 pistons. I think everything else sound pretty good, excepting those heads. If you haven't opened up the exhaust ports, and are going to run those big valves, you're kinda going the wrong direction. You would be better off to open the ports and run stock valves which would give you better velocity air flow, which would help on low end. With big valves and small ports, you pump a lot of air into a restricted area and it takes a while for that air to get moving, so not good for low end. (Am I thiking right about that?) I think so. Anyway, I'd defenitely open up the exhaust ports. I'd go with the middle cam with your intake. I'd say carb is at least 100 cfm too large.
Um i'd say in order to take full advantage of the cubes, step up to an RPM intake and a slightly larger cam, something in the .500-.520 range. Those mid-upper 400's u listed are a little small as far as i'm concerned. And the carb is also too big. Even with efficient heads, a 750 is more than enough. I'd think you could get by with a 650 but to be safe I'd go with a 750. Speed Pro H273CP pistons would put you around 10:1 or so which would benefit you quite a bit to make up for the restrictive heads but definitely open up the exhaust ports and get rid of the thermactor valve. I haven't got the desktop dyno sim but my guess with the combo i suggested should be around 350-375 hp if all done correctly... Just my $.02
I agree with everything Wreckit87 said except for the cam. I would go for a longer duration cam, to allow time for the air to get through the restrictive ports, and to keep from having to get larger springs. You should probably still change springs, but a 2.18/2.24 @ .050 w/ .475 or so lift will allow you to get by with the cheap comp springs. Again, I may be thinking about this backwards, I have a tendency to think dyslesic at times, so if anyone disagrees, let me know, as you probably know more than me anyway. That's my .02, worth about .01.
Agreed, I suppose .475 would do the trick with the restrictive heads, but I've just found that higher lift and shorter duration seems to work out better for me... I had a 268 Lunati cam with 522/538 lift on stock springs and turned nearly 6500, and had excellent off idle power. I also have a 300* with .540 lift custom cam research grind that was an extreme pooch with a heavy car and factory convertor. In a heavy truck like this, I'd think he would wanna stay with a small duration unless he wants to go crazy on the stall and reduce the streetability. But i could be wrong too i guess i don't know a lot about the heavy trucks but i built a 351 for my buddy with that used that 268 Lunati, it dyno'd 360 hp and over 400 ft/lbs and will bust 35's loose with 4.10 gearing and a stock stall in a C6... IDK
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desktop dyno guys???? 393 combo
Uncle Ted
