383 stroker - components and hp
 

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.

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

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.

I am running a 383 for the 2nd season, rebuilding for more hp for the spring :D 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) :D


Travis

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?

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

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.

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?

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

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.

Thanks 220. Santa doesn't bring cams to our house, just fur coats.

Hint...Put your own cam of your choice in the sleeve of the coat:eek: :D :D

Also Guys...two friends of mine both run 406 and 408 sbc's. One guy started with a 350 mag , did the 325 crate engine thing(wasn't satisfied). worked that over to 383 and Vortec heads (wasn't satisfied) , and finally went to a 408( kinda satisfied:crazy: ). At this point his boat has about reached its limit for power and speed , anything more could be suicide.

Summit and Jegs offer the stroker kit, check with a good machine shop as well when they do your block about if they can get the kits as well.

i run a 350 @ ~ 410 crank hp through an alpha SS at 5500 rpm... not a hiccup for the first season on the drive but this is in a light hull also (16 donzi classic).

i do a few performance engines on the side during the winter months for summer play money and i've often looked at the cost and benefits of a 383 vs say a 434. the 383 can be assembled economically or it can be put together with a big price tag. this all boils down to the hp, torque, rpm and intended use of the motor. if i was gonna spend the money to put together a sbc that i wanted to make BIG torque and HP numbers and be able to run at high rpms continuously (say 5500 and up) and have it last i'd spend the money and look at a 434. You can find complete rotating assemblies, short block kits and longblock kits at various locations for reasonable costs. you can achieve 525/525 out of a 434 running her under 6K on 92 octane and keep it pretty mild (only a SLIGHT lope)...

check out www.shafiroff.com

this in no way is meant to detract from the abilities of a 383! i love them too but figured i'd toss a twist in for good measure :)

I am also a FIRM believer in Pro-Action cylinder heads... both for the performance they offer and the pricetag. i also prefer the roller camshaft route :)

6" rods will be better for both worlds provided you are aware of the price for the pistons & rods. However no matter the quality of the piston using a 6" rod you have to go the extra mile to insure that you have a detonation proof engine. The problem is on the small Chevy w/ 6" rods is that the piston rings are set so much higher on the piston that there is not enough meat on the piston between the rings. I have seen many strokers die this way. Now Travis has some hi dollar equipment in his horse that will allow him to maintain 6000 and even 6500 RPMs for quite a few seasons. If you go out and buy the basic Jegs stroker kit then you will actually be limited to the RPMs you can turn (wouldn't go over 5000 sustained)

Another problem is when you go with a stroker you have to be careful about the clearance between the rod bolts and the cam lobe. A big cam will get you some interference problems. This is especially problematic when the block has been align bored (let's face it sometimes it is necessary) It may require special rod bolts and or a dremel tool.

Roby

Currently running 335's putting out about 425 HP...........Tore then down at 400 hours looked great.

These engines spin 6000 rpm's all day long, and have .600 solid rollers in them.

Take your time, use pretty good parts, double check everything & you'll be fine at the HP you want.

I'm sure of you used premium parts, you could get to 500 HP on pump gas, but you'd need good heads, an intake & cam.

Just my opinion.