rob vanharten

So speaking of cams, what would be some suggestions to take full advantage of my new heads, comp ratio, and keeping good valve train reliability and a hydraulic is a must. I cannot remove the valve covers with the motors in the boat! And what hp gains would be seen over my current cams??

Full Force

iTrader: (5)

Flow heads, make sure you have all other info and what boat it's going in and call 6-8 cam grinders, pick the one that is most offered, that's what I did stay tuned for results lol

getrdunn

iTrader: (7)

If you go down that road Jim will lead u in the right direction. Ask him about the grinds he used in the 540sc's he did over on the east side of the state. They work well with NA builds also but I think you'll be ok with your cams considering the gains your going to have in the head flow unless your going to wanna really turn up the r's.

Btw don't let the carb thing bother you but by all means if norm is willing to come down to dyno session to help out and try a couple different carbs. It's a win win for everyone including himself. Like you said you can always strap a couple of his on down the road. This is the kind of stuff that can keep you from sleeping at night. The time when you should get some sleep but your mind goes into hyper hp drive. Lol... happens to all of us.

getrdunn

iTrader: (7)

Be careful listening to to many cam guys you'll be all messed up in the melon. You get to big you'll lose your velocity and ports will become lazy and lose efficiency. Let the heads do their work.

articfriends

iTrader: (1)

Yes, he likes to start with a holley 4150 850, he also builds dominators but swears until you break 800 hp and especially in the 600 to 750 range a dom will never beat a 4150 that flows equal air. Once you have 2 carbs that flow in 1150 cfm range, its not air flow as they flow same, its fuel atomization and flow curve of boosters etc. I would love to see his 4150 against a dom on a different dyno than at my shop as i have had people imply the testing i did was canted to favor his carb. I dont sell carbs, i actually hate them as i am a efi guy, i was just beyond impressed as to what i saw testing 4 different carbs on my motor. I always figured a custom carb done right was worth 2 or 3 hp, not any more!

articfriends

iTrader: (1)

Norm dislikes the 950hps and qf bodys that also look like the 950s, he says though they look cool with their casted body that looks hand worked, the flow sucks compared to leaving the divider wall between primarys and secondarys and working it, to effect of 20 or 30 cfm, he says the guy who designed that which i think was braswell sorta knew this but holley went with it because looks sell

getrdunn

iTrader: (7)

velocity key while maintaining good signal. Head and intake port velocity gets brought up often but carbs nowhere near as much while funnel affect works also but back to back testing challenges that theory but again each build can be different. Looking forward to the results moving forward. This kind of thread is great for everyone.

MILD THUNDER

iTrader: (3)

There is no better test, than trying things back to back on a dyno. Swapping cams, is a pain in the azz obviously, and rarely done. Swapping carbs out, no brainer. Easy as pie. But sometimes, what works on one engine combo, may not work on another. Something as simple as the camshaft events, can change the way things respond. A cam with more overlap, might respond really well with a bigger carb, than an engine with less overlap, or different timing events.

You can have an engine that shows it's using 980 CFM worth of air to make 700hp on the air turbine, and then change camshafts, and have an engine thats using 1030 cfm of air, and make 700hp, or 680hp. If the additional airflow is going out the exhaust via overlap, or exhaust timing events, or a dozen other things.

You gotta decide on the cost as well. Dominators are typically more expensive than a 4150 carb. Tim Full Forces carb, costs about 750 bucks if I recall. A custom 4150 carb, can cost twice that. When we dyno'd tim's engine , in full Marine dress, with his exhaust and accessories, a couple changes to the jets, and his air fuel ratio didn't vary from 3000 to 6000rpm by much more than about 2 tenths of a point. In the boat, if I recall, he also had a pretty linear fuel curve for cruising, and wot. For an off the shelf carb you can have at your door in two days, I'd say thats pretty dam good.

20hp gain is a nice gain for sure. Would I spend the 1600-2000 dollars for an extra 40hp (twin engine boat), myself, probably not. I am a cheap bastard, and in my boat, 40hp total, is probably worth 1, maybe 2 mph at best. I'd be more concerned about the fuel curve of the carb, and whether or not I can make changes to it. Thats why I got rid of my old 1990's holleys for the 4150 quick fuels. I like screw in air bleeds, screw in power valve restrictor jets, and so on. This way I can tune easily on the water with a wideband. Trying to fine tune a twin carb blower motor, with only main jets, can be kind of limiting.

I know that eddie young borrowed a quick fuel 1050 B2 blower carb from us. He had built a mild HP500 upgrade. Mild cam, brodix heads, dart intake, basic budget combo. It made a chit ton more power than the stock HP500 carb. Of course it took some tuning as the carb was setup for a twin carb blower application, but none the less, when all said and done, he picked up a ton. I don't remember the exact number but it was like 60HP to the better. That was an easy sell to the customer after trying that carb out on the dyno back to back with the original carb.

5050

big cube engines like a wider lobe sep. I think 114 would be better to carry torque flatter and longer without drop off and more lift where the sweet spot of flow is in heads. Torque is what pushing a prop. I'm gonna say ur set up will be close to this pic dyno sheet. Zz572/620 in my last boat. Engines wouldn't pull past 5450 in my last boat [ATTACH=CONFIG]565973[/ATTACH]

MILD THUNDER

iTrader: (3)

Icdeppl's 548ci 900hp carb'd roots engines. Twin 1050 quick fuels, out of the box idle circuitry. Engines stone cold after startup in this video. He runs no water stats, so the engines never build any heat in them. They will idle at 950 in nuetral, 700 in gear, and idle all day long without fouling a plug, or stalling while shifting around the dock with 17.75" cleaver props.. I've seen some high end big name built 900hp roots engines, that surge like a MF'er, stall out when shifting around the docks, blacken the transom after 1 day on the water.

https://www.youtube.com/watch?v=a2R0Ly41uvo