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I have a stock bore 400 SBC that I would like to put in my jetboat with Dominator pump with "B" impellor. I would like a recipe for 500 HP. These are the parts I have for it already.
I managed to obtain some 400 pistons that take a 5.7 rod. They are 12.5:1 forged TRW's. New in the box. The 5.7 rods are PINK rods from a 350 SBC Targetmaster 4 bolt main. I'm a little concerned if the crank will hold up. I'm also concerned that the only good heads I have for it are Camel Hump heads with really small chambers....like 58 cc's last I checked. They have 2.02 intake 1.80 exhaust. I would like to run the VORTEC heads because they flow so good, but if the camel humps will do the job, I would rather use those. I'm just worried about that high compression. Oh yeah, the heads are already set up with the big springs and studs and have already been machined ready for use. Again, compression is scaring me. I would like a combo that can run on 93 octane with a booster if needed. I would also like to use the parts available if possible. Obviously cam choice is what I need.......do I build this thing for torque or horsepower? Any advice would be greatly appreciated.
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Head casting numbers, or, better, flow bench numbers from the actual heads?
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Geeezas , Will a 12.5:1 slug clear a 58cc chamber ? :idea:
This combo is for a 383 so you should see slightly more with 400ci.
Heads ~ AFR195cc (260cfm)
Cam ~ Comp mec. roller XR274. 236/242 @ 0.050.D 0.564/0.570 Lift. 110*lobe on 1.6 roller rockers.
Edelbrock Victor Jr. intake and a 750 DP Holley.
Makes about 515hp@6,000 510lb-ft @ 4,400.
Good Luck
T.
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12.5 with those heads? Do you know what springs are in those heads? Cheap Thrills, are those cam specs with the 1.5 rockers or the 1.6? Sounds like a healthy combo ;)
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12.5 with those heads? Do you know what springs are in those heads? Cheap Thrills, are those cam specs with the 1.5 rockers or the 1.6? Sounds like a healthy combo ;)
Yeah those 12.5:1 slugs in 58cc chambers just doesn't seem like a good idea to me either. :D
The Rockers are 1.6 in that combo.
T.
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I mean are the cam lift specs figured with 1.6? The larger rocker will add some lift...
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Sorry for the delay in getting more info about the parts I presently have. I was concerned about using those big pop-ups in such a small chamber:eek: !! Anyways, my weekend from work is about to start so I'll go in the shop and get the numbers off the heads. I'm thinking really about getting rid of those pistons and get some cheaper hyperteutectic (spelling:idea: ) pistons. The boat will probably never see nitrous. I would like this boat to be fast but not at the expense of blowers, nitrous or turbos. A tunnel ram just to give it a cool factor is what I'll probably do later on. I'll give up some more info on what I have tomm. Thanks guys for your input so far.:D
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I mean are the cam lift specs figured with 1.6? The larger rocker will add some lift...
Cam Specs were with Factory 1.5 rockers.
Took me a while to dig that up sorry for the delay.
T.
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The camel hums are usually the 461 or 462 heads, the only difference is that the 461 heads do NOT have the accessory holes. These heads can flow as good or better than some Vortec heads with a little work. If that's what I got, that's what I would run.
MAKE SURE YOU DRILL STEAM HOLES IN THE HEADS TO MATCH 400 GASKET.
I personally would just use a flat top piston with the 400 on 58cc heads. Better squish, predictable combustion and timing. And you would still be up there in compression ratio.
This part may start an argument: I would run water/alky injection to cool the intake and control detonation. You will be able to run 92 octane with quite a bit of timing on the flat tops. You can use a nitrous plate to spray the water/alky mix. (windshield washer fluid for cold weather works like a charm).
Aquamist makes a good kit.
OR- build it as a 377 and keep the big dome pistons. Your compression would come down slightly but your RPM range would go up. Remember, it's the low-mid RPMs under heavy load that breeds detonation. A 377 with a dual tunnel with a couple of 500's will scream with lots of cam and 1.6 rockers.
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I would stay away from Hyperutetic pistons in a marine application. For the price of a set of Speedpro/TRW forged flattops it's cheap insurance. Go with a forged flattop piston and a set of aluminum heads so you can safely run on 93. There's no sense running an iron head with high compression in the marine enviroment. AFR, Dart, Brodix all make nice aluminum 195-215cc heads that would suit you application. I prefer AFR and run their 190cc's on my 355. I would at least want a 195cc or better yet the AFR 210cc head on a 406ci. I really like the Crane 230/238 .528/.5?? 112LSA hyd roller for 383 and 406ci SBC's. Comp also has a nice 230/236 112LSA hyd roller. How high do you plan on spinning the engine? I don't see a Vic Jr being needed if you don't spin above 6000 rpms. The RPM Air Gap is stronger in the low and midrange and holds it's own over the Vic Jr until around 6K. A Jet needs torque bottom line. A Holley 750 or 800DP will work nicely.
If you don't want to pop the coin for aluiminum heads and plan to use the stockers definately pop for some new flat top pistons. The 58cc and 12.5-1 domes will not work. Getting 500hp from a 400ci is pretty easy but will ultimately come down to how well the heads flow. The better the heads flow the easier it will be to reach your goal.
Are you planning on using the stock 400 crank?
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I'm with Ryan pretty much.
Since 500hp from a 400 is relatively easy with today's induction/cam packages people like think since it's easy that it must not be much power and therefore don't thing about the shortblock. Good machine work and a forged rotating assembly should be used, especially since this is in a boat.
400cid or more loves airflow. 200-215cc heads (AFR, Brodix Track 1 and etc.)
Good news you can make this power with 10:1 compression and 92-93 octane with no octane booster.
500hp is not cheap but it is not killer $$ either - do not skimp.
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Ditto on the Hyper's. They're durable, but brittle, and don't take much in the way of detonation. The stock 400 crank should be fine with some decent prep, and good machine work on the block. Like CFM said, 500hp these days isn't radical, but will require some attention to detail, and a certain amount of investment to make sure you don't end up with a pile of scrap after a few hours. The other thing to keep in mind is where you want the 500 hp. It's all together different to build a 500hp circle track engine than a reliable marine engine with the power in a usable rpm range. Do your homework and get the right parts combination the first time and not have to spend wasted time and $$ re-doing things a second time around.
Edited to add: The steam holes in the heads talked about above are a must with the 400 block.
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Sorry it took me so long to get back with you guys, been busy getting a free 454 BBC out of an 86 motorhome, don't remember the brand. It was sitting for 15 years, but the motor does turn over. Previous owner put 100 k miles on it and parked it, got sick and left it his backyard. He passed on and relatives wanted it gone. This thing was trashed from mold and soft wood.:eek: It is a total scrap project. It was alot of work but a free 454 is hard to pass up.:D Plus a good chunk of change from scrap metal. So now it looks like that 400 can sit on the engine stand for something else. I starting to look at what I might need for the BBC. My boat presently has the 350 chevy so I know the BBC will bolt in its place but will I need a different PTO adapter ? I know what will hurt in cost is the OT Rewarder headers. I'll definately run the correct cam and intake. Any other major parts as far as coupling it to the pump I might need? :idea:
