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Nmocean
06-29-2008, 06:13 AM
I had 454 built to the 420 specs but with large oval port heads. I built a 454 stroker to a 496 9-1 cr. balanced blueprinted, a custom grind comp cam with the 4-7 swap 551in/.557ex; I had the large oval head valves replaced with 2.25/1.88 11/32 stems ported and flowed; I am running the same ign DUI, the same intake with a 1" spacer eldelbrock rpm air-gap but now I am running a 850 sea demon and revolution exhaust no mufflers. The engine now pulls hard low and midrange, but the top end is flat I can turn about 52-5300 rpm with the same prop I had last year 24 bravo 1 labbed; I would think I would have more power on top also. In another word the boat is the same on top as last year. But now it is much, much quicker.
TIMINATOR
06-29-2008, 10:37 PM
What is the duration at .050 on the cam, and what is the old and new rpms? TIMINATOR
Nmocean
06-30-2008, 05:22 AM
.050 230in/236ex
justfloatn
06-30-2008, 01:04 PM
If you had 420HP before. I don't see anything in your build that would get you over 480HP to net a big top end gain. You may have only picked up 4 to 5 MPH. Right? The stroke will add torque to the midrange which you feel in your acceleration. But those heads are not going to get much more than 500hp. If it's top end you want I think you need a better set of heads in rectangle port and a different cam. IMO.
On a side note your motor is exactly what I want to build this winter for my boat. Good torque motor for acceleration and a 5300 to 5500 max RPM. Sounds like a fun motor in a 21' to 24' boat :D
Nmocean
06-30-2008, 02:12 PM
The boat is extremely quick compared to the way it was before. It just falls flat on top. Everything is bigger except the prop is the same I did not pick up any top end speed. It is just a ton more powerful.
justfloatn
07-01-2008, 06:06 AM
The boat is extremely quick compared to the way it was before. It just falls flat on top. Everything is bigger except the prop is the same I did not pick up any top end speed. It is just a ton more powerful.
Then use that power to turn a 26P. Problem solved:D :D :D
Nmocean
07-01-2008, 07:20 AM
My friend has a 26 bravo 1 that I am going to try that is what we are thinking I am also going to try a 25 mirage plus to see what it does. I think wiht the stroker I lowered horsepower band, which in turn would let me turn the larger prop.
Nmocean
07-03-2008, 06:07 PM
Anybody want to recommend a cam, I am already looking for heads aluminum rect ports