cstraub69@comcast

Don,
What is your target HP and RPM range? After that I can give some imput.

Chris

chromecat

650+
9:1 CR
5500 rpm..

Don

cstraub69@comcast

Okay,
No problem. Please e-mail me at [email protected]

Chris

blue thunder

Just remember chromecat, what ever he recommends for a carb will need to be upsized 30% Just kidding Chris. This is a great site!! I've learn a lot here.

Dave

cobra marty

Finally someone else who knows and believes in TQ! Build for TQ and the HP will follow.

blue thunder

Not to burst anyones bubble, but hp is torque. HP is torque at rpm. No difference between torque and hp other than the rpm factor. In fact at 5252rpm hp and torque are equal. Hp is measurable and real. That said, of course torque (force x radius really) is what moves boats. HP tells how fast it will go. Throttleup had a great post describing this fact early in the thread.

As far as exhaust goes chromecat, I'd select an exhuast that has a true runner length to maximize hp gains.

BT

WETTE VETTE

When I ran my 13:1 compression 496 in my Baja I started with a Nickerson stage 5 850, which flows 980 CFM. The boat ran great and I saw top end speeds of 95 to 96 MPH and great acceleration. I wanted more top speed and contacted Nickerson and he built me a stage 5 1050 that flows around 1175 CFM. I ran a dart 4150/4500 adaptor and kept the same Merlin single plane intake. The acceleration was BETTER and the top end was consistently in the 96 - 98 MPH range. The Baja is a light boat that doesn't take tons of torque to get it going. From a 3000 RPM cruise the RPM jumped instantly to 5500 and then ran up pretty quickly to the 6300 top end. On that combo the Dominator won hands down!! On a heavier boat with a hydraulic roller and less head and less max RPM the smaller carb would probably be better. My new motor is a solid roller CNC head 598 and I am starting with a Nickerson stage 5 1250 that flows close to 1500 CFM. If I need more I will go tunnel ram and 2 1050's.
Craig

blue thunder

Using wette vette's example above with the 950cfm carb he was at 108% of engine cfm. With the carb that performed better he was at 130% of the engines cfm. Not to belabor the point, but 130% is a good start point on a marine application when looking for top speed.

BT

WETTE VETTE

Keep in mind many factors are involved with cam and carb selection. Call a true custom cam grinder and see how many questions he asks. Not only does he want the obvious like boat weight, head type, etc., but he also wants to know what the boat is going to be used for primarily. If you say things like smooth idle, relibility, or any comments about needing low end power he will recommend a particular grind. If you say "race boat without the numbers", which is what I normally say he will recommend a completely different cam grind. For all around pleasure use Crane and Comp have a lot of cams to choose from. For maximum performance look to a custom ground solid roller and get a carb to match. Or go with a big blower and get big power and valve train relibility with a smooth idle!!! Did I just say that!!
Craig