bouncedcheque

I've reviewed many threads re: 383 stroker. Can you build one out of a 350 mag that will get you 425 to 450 hp? If so, what is the key? (besides a alot of $$$). Thanks in advance for any info.

mikev

yep just bore it 300 over and put in a sbc 400 crank you can get the kits from summit racing or jegs.

Gary Anderson

Yep, kits are available for 383s. Now a reliable 450hp out of one is a different question. And what drive is it hooked up to. Alphas are generally not reccomended for that hp.

traviss

I am running a 383 for the 2nd season, rebuilding for more hp for the spring This summers motor was a new 350 block with a .030" overbore ( cause i couldn't find good parts for standard bore blocks). I run a 3.75" forged 4130 eagle crank, two years of hard running and not a scratch on the crank, 6.00" rods with JE pistons( 10.9:1 on 110 octane). I also used all crane roller valvetrain and AFR heads, edelbrock victor jr and 750 holley, Was a very nice motor. This winter it will get a clean up bore, same parts just new pistons. cam and valvetrain. This summers motor was just around 500-510hp. Spun it at 5500 rpm all summer. In the spring I am looking for it to make in the ballpark of 570 hp and to spin it around 6000 rpm. This boat is 18.5 ft and about 3000lbs, with a alpha drive, I drive it hard and the alpha has never let me down, have not broke it yet. ( knock on wood)


Travis

220BR

Traviss, you're my hero! Has the Alphas ever been rebuilt (IOW, did you use tighter preload, etc...)?

What kind of outdrive oil?

Outdrive Shower? Thru hull exhaust, I assume?

Why did you choose 6" rods?

traviss

Never rebuilt the alpha. I only put new seals in it usaully ever winter, everything looks great everytime I take it apart. I don't worry about much unless I see alot of metal on the gearcase oil drain, haven't seen much of anything coming out. I use a Sirmek summit drive shower, with 11 water ports, i drilled them out alittle bigger to flow a little more water. For gear lube I use the standard merc high performance lube, changed about every month.

For exhaust I have thru hull. EMI thunder exhaust with stainless risers..

I was buying new rods anyways, so there were few minor advantages of the 6" rod. If a 5.7" rod is used there is a little more angle which puts more stress on the cylinder wall. I thought I was buying new ones so might as well be 6"s. I have been using them 2 yrs now and no problems, eagle forged H -beam 3D rods with ARP cap screws. Upgrading the cap screws this time around. They do clear a normal camshaft, so no need to use a "small base circle" cam with these rods.

I used a new Gm block this time and it was a nice piece. I bought the chevy "383" block which is already clearanced for the rods ect, I still had to grind a litte more out. It was $840 if i remember right. If you can use the 1988 and up year blocks, they are machined for roller cam already, and the GM roller lifter setup is nice, I have used there lifter kit with these motors and have never had a problem, they sell the kit for $180, 16 roller lifters, 8 guidplates and a guidplate retainer. You can get away with using the GM single roller timing set, it fits the block nicely I used in the first motor, if you want to use the double roller timing set, right behind the cam sprocket needs to clearanced, I took a carbide grider and made clearance to run the double roller..


i think maybe wette vette might chime in, his dad runs a 355 chevy with over 500 hp.

Travis

220BR

Thanks for the info on the Alpha. I'm in the same boat (hah): 383+Alpha, but I still have thru-prop exhaust.

I understand about 5.7" putting more stress on block wall/skirt, but the corollary to that should be that the 5.7" has more leverage (mechanical advantage) at peak cylinder pressure than the 6." Isn't that right?

Anyway, I had been told that 6" were better for high rpm and 5.7 better for torque, so I went with 5.7 (Scat rods and crank) and forged TRW pistons. I'm presently under-cammed and poor-headed, so I only have about 360 hp at 5200

I'm hoping for a new cam for Christmas.

Bouncedcheque: others here know more than I, but the key is the head/ cam combo, with an exhaust to match. I would *think* something like 72cc Iron Eagles with a Comp XR 282HR (maybe even the XM 276HR) would put you there. I'm assuming your Mag already has rollers.

bouncedcheque

Thanks. I was hoping you guys would jump back in with an update on your motors. I have a brand new Bravo One drive, so should be O.K. there. The limiting factor will probably be the need to run on 87 octane, as that's all that's available to me on my lake. Those are some awesome numbers Travis; How fast is the "flying coffin" going?

bouncedcheque

Also, I currently have the mpi set-up and am wondering if larger fuel injectors would also be required.

220BR

Again, others here know more and have more experience than me, but I faced the same type of situation. My design parameters were: iron heads, quench between 0.040 and 0.045 (supplied mostly by head gasket); dynamic CR 8.2 or less.

Mine came out at quench=0.044 (.039 + .005); SCR=9.8
DCR=8.36. The DCR will drop to 8.17 with the new cam. I've had no problems with 87 octane.