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Pentstar web site?

2759 Views 24 Replies 7 Participants Last post by  AdventurerSport
So I was looking for some engine info the other day and ran across this Pentstar discussion forum on line. Its not a big site or anything but seems friendly enough. Anyway I invited a guy who was responding to some propane posts I put in to visit us here. Be surprised if he isnt here under a different name because he apparently has a 76 powerwagon short box 4x4. But heres the thing. He says he has a stroked 383 (431 cid) that is getting 18 to 22 mpg. Thats with 3:55 gears, 10.5 compression on low octane pump gas, carter 2v carb, 906 ported milled heads, forged flat tops, doesnt rev over 5000, and full time 4x4 tcase. Now thats something. Cant see it myself, between detonation on 10.5 compression, or 18 to 22 mpg. But I'm no expert. Anybody think this is doable?
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And what do you think of 10.5 compression on cheap pump gas and getting that mileage? It might be possible to run 10.5 on lowest octane pump gas if you are spinning off the compression with the cam, but my understanding of that combination is a high reving engine producing max torque and hp at 6000 or better, low power in the lower ranges because of the cam. Somebody please correct me if I'm wrong.
We need more info on this. You wrote on the other site that you are dyno proven at 358 HP and 656 torque. Need some details cause I would love those numbers. Also how are you running that high 10.5 compression on 87 octane pump gas?
I looked into (briefly) the chamber / piston coatings but didn't really run across anything very realistic. Not sure in a chamber how the coatings would do anything but keep the heat in anyway. I'm not calling anybody a liar by the way. I just want to know if this sort of power etc is really doable. Hey, your not JS on the other site are you?
This isnt anything but an attempt at getting some details. You said its not a ross kit so what pistons are you running. A 440 crank in the 383 block interests me. What rods and what bore is the block. The pistons are flattops with very little milling of the heads so they gotta be pretty much zero decked, right? 906's with nice sized valves are nice heads. 383 stroked is a nice engine. Its just some specifics that would be nice. What rpm did you get 358 hp and and what rpm did you get 656 torque on the dyno. How old was the rebuild when you put it on the dyno. What hints and suggestions can you give us. Thats all I can think of. Thanks.
I'm trying to learn as much as possible before my rebuild. The mileage is good. Not impossible to get on a full time dodge truck, but pretty engine / gear dependant. But the compression number on 87 pump gas is real tpough for me to accept. Also how do you get 10.5 compression on flattops with open chamber 906's with very little milling? Flat tops would be out of the block would'nt they? Which I guess is ok if you can keep the rings low enough. I dont know, and its this sort of thing that I would like to know. Also 656 lbs torque at 2000 rpm or less with a 500 cfm 2 barrel carb doesnt make sense to what I know about how this sort of power is obtained. Now I'm not calling anybody a liar. I dont know enough to do that, and I dont like that anyway, but this aint making sense to me. Somebody who knows how this can be done please let me know. And what pistons are those? Its a b block with a 440 crank and 440 rods, right?
And I am building a 383 but with the forged B crank, mostly because I though the numbers were good enough but if I can the kinda results your getting maybe I should give it a new direction.
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