SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: crussell85 on February 02, 2014, 10:09:27 AM
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So I'm set on building a 383 for my 2001 Glastron GX205 this winter/spring. This is what I'm thinking.
Scat rotating assembly 3.75" stroke, 5.7 rods, 18cc kb d shaped pistons.
GM Iron 062 Iron Vortec Heads, may step up to the GMPP Small Port Bowtie Vortecs (not sure yet)
Crane Cam 2032 2032 Hydraulic Roller Camshaft for Chevrolet 1987-1992 V-8, 305-350
Possible Crane Cam HR-284-2S-12 IG Hydraulic Roller Camshaft for Chevrolet 1987-1999 V-8, 305-350
GMPP Vortec TBI Intake Manifold
Was originally thinking the second cam but would like to be able to run this on a GM tbi system and not sure how the efi will like the second cam.
I will be running thru hull exhaust as I 99% of the time boat on the Grand Traverse Bay, traverse city, MI so there shouldn't be an issue with noise complaints. May eventually install a captains call system depending on how loud it actually is.
Outdrive is a Volvo Penta SX 1.5:1 ratio.
I'm not really putting a budget on this build but it has to be realistic (you know what i mean)
Just looking for opinions or suggestions on my parts list.
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I'm building a similar setup for my 76 swb chevy.
010 4 bolt block
400 crank turned, drilled and knife edged
6 inch I beam rods
Kb flat top pistons forgot what the cc of the valve reliefs should be around 11:1 with 65cc heads
vortec 062 heads off a circle track crate engine
RHS 23 degree ez efi/carb single plane intake
Undecided cam and carb
One thing to look out for with the vortec heads (atleast the 062) I'm not sure how the bow ties come but the RG clearance on the stock head allows for only around .460" of valve lift before the valve retainer will hit the top of the valve guides. Alexsparts.com makes a spring and retainer kit that allows for .550" lift without having to have the heads machined and have the guides cut down and the seats cut for bigger springs for 100 bucks. Also FYI stock size sbc valve springs will not fit vortec heads without the seats being opened up. Check out alexsparts.com for his line of vortec head stuff. He's got everything you'd need even the valve spring seat and guide boss cutting tool if you wanted to DIY.
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Oh and the vortecs respond better to a split duration cam. The exhaust needs to open up more and stay open longer to
Move more air being that's the weakest point on the vortecs. Just my 2 cents from what research I've done
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From a horsepower standpoint, my vote for the Bowtie heads with the larger Crane Cam HR-284-2S-12 IG cam. I like your cam choices, either should work well in your application. Both are ground on a 112-degree lobe centerline and looks like they are ground advanced 5 degrees to a 107-degree intake lobe centerline. Either should work well with TBI and have a smooth idle.
If you are expecting more operation in the lower RPM range, my vote for the smaller Crane 2032 Cam. Match the build to your intended use. How often will you be running at WOT or racing? If you are mostly wakeboarding or cruising, you will like the smaller Crane 2032 cam better.
With your pistons at zero deck, your combination will have around 9.6:1 max compression ratio. I would recommend tightening up your quench by zero-decking your block to maximize your compression and resistance to detonation. You should be able to easily run pump gas. You might even get away with running the cheap stuff.
I would expect 400 to 430 HP in the low 5000 RPM range with > 450lb/ft torque around the mid 3000 RPM range, on pump gas.
Cheers,
Joe
P.S. Sorry, I am not qualified to comment on your outdrive or how it will work with this engine.
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I don't plan on racing the boat. Maybe a few times a month it might get some good wot runs but not all day long until the gas is gone. I would love to be able to pull two tubes with two people each in them. If the boat gets to fifty five sixty I'll be good with that. Max speed majority of the time will be around forty.
Yes I plan on zero decking the block to hold a .041 quench distance. Aiming for around 9.5:1 compression. A point or two over will be fine. My boats always drink premium grade fuel.
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That's a lot of can for a 383.....
Potentially if you go that route I would recommend playing with the rocker ratios on the exhaust. There are much better can grind choices out there. The GM Performance Parts "Hot Cam" is among one of them.
Your best bang for the Buck would be to keep an eye out for a DuoProp lower.
Sounds like a sweet project.
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