SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: beerjet on March 25, 2008, 04:18:28 PM
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For a 468 BBC. Nothing amazing . Nosty motor so it'll probably run 5k - 55k . I kind of already have an idea of what I want . Lookin for some insight since it's always good to get some outside opinions . Thinkin rectangle , iron , definatly not more than 315cc .
-beerjet-
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Keep it an Oval, these bad boy jets need the torque..... my $0.02
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I did several similar "searches" Omar. Dart has a real good rect port, 305cc I think, comes very highly recomended, Canton/Cantfield something like that makes a 310cc rect port that also was very highly recomended. You're right, definately not more than 315 cc which rules Merlins OUT. Racingjunk has the Darts on there quite often. The Darts are iron and the other are aluminum. I was told iron for your river boat and aluminum for your race boat.
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Race gas is the only thing I'm feeding it sooooo. I was lookin at the dart Iron Eagles mainly for the price . If I was a baller , I'd be all over the Dart pro 1's or AFR's . There is also the Brodix ovals which look tasty but a little pricier . The Brodix pieces are well worth it though .
-beerjet-
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I forgot all about the AFR's. A lot of Chevy "in the know" guys like the AFR's. I don't know anything about Brodix other than no one recomended them to me when I was looking.
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You must choose a cylinder head before you purchase a piston. All of the above mentioned heads have different valve angles and require different pistons. Are you building a compression motor??
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You must choose a cylinder head before you purchase a piston. All of the above mentioned heads have different valve angles and require different pistons. Are you building a compression motor??
nothing wrong with this, but i went opposite i did my botum end so i can "narrow" down my cylinder head choices...when it comes to chebby motors the possibilities are endless really
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...when it comes to chebby motors the possibilities are endless really
In a jet boat, if you run a cylinder head with too much air flow you'll have to cam it and up the compression in order to actually make it an advantage to have that much flow instead of a disadvantage. A lot of those big number flowing heads are designed with 500+ cubic inches in mind. Then you have to match your pump to your engine, talking about changing to minumum C or D impellors with inducer's pre-loading those pumps.
Or you can get a good flowing but not oversized runner head(s), match your cam and compression to the heads, and get more power in a lower more useable range for a jet drive. I think that's what Beerjet is looking to do if he's looking for cylinder heads with a max flow of 315. IMO
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Rod your not picking up what im laying down are you
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Rod your not picking up what im laying down are you
:banghead: It's not sounding like it. :banghead:
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I know where there are some bare Dart Pro 1's for $1099 Brand New. There is nothing wrong with going rectangle on a jet boat. Keep in mind as soon as you plane you are at 3K +++. Jets love fuel and live above 3500 all day. Now if jets need torque, torque, torque, then why do tunnel rams work so well?? Arent tunnel rams a top end puller?? Rectangle will give you the velocity you want and you will have a ton more choices in cylinder heads. My setup is a rectangle tunnel ram matched to a oval port head. Eventually I am changing to a better performance head but Dale at Hondo said it works really well.
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A 315cc runner is a rectangle port runner.
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lemme start in dummy terms...because someone started talking about pistons and all that technical stuff i think we have gotten off topic...if omar is looking at doing pretty much everything i think he needs to start from the bottum and work his way up...like i said in the aftermarket especially with chevy you can pretty much find anything you want...no one said he needs to go with a top cylinder head like a big chief or some shit...i think he needs to start with the bottum...if he is using this rotating assembly that was included start with that...is it a flat top...is it a dish...or what not...and figure out your cam then top with all the goodies like the head that is most likely to work with that and your cam...cams im dumb there, but have an idea...i think honestly that if you use some common sence and the knowledge of some of the few on here...you can do a really nice BBC setup that will last forever...and make the power you are looking at...in all reality it sounds like omar already knows what he wants...and i see no problem with his decision
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Call Jim Brock after 10 minutes of talking to him on the phone you will realize just how little you know about boats and you will hang up and kinda sit there with ur mouth open wondering why 90% of what you were told or want to buy is wrong from everyone else around. Jims knowledge FLOORED me.
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Call Jim Brock after 10 minutes of talking to him on the phone you will realize just how little you know about boats and you will hang up and kinda sit there with ur mouth open wondering why 90% of what you were told or want to buy is wrong from everyone else around. Jims knowledge FLOORED me.
hehehe, i love talking with jim :banghead:
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Blue is you Tunnel ram matched to oval port welded in or has it been epoxied in or have the heads been ported from large oval size to rectangle have done this to several heads the set i have done know is closed chamber 101cc small plug # 3964290. Intake could be full size the witness line in picture is full size of rect port. the head has a 2.300 int in now i will custom build a 2.275 valve for it. may run these heads at river in June on fltb . these head
pull hard in jet from 2800 to 6000 with 2.250 valve. not to big not to small
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more pictures
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Elwood, what's with the Dye and the lines drawn to the valve seats?
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To set seat depth gauge on each side of pilot
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picture not where there was
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Very interesting set up, haven't seen it measure that way before