Thread:

Cast T/R

With that many inches your HP should be a walk in the park. You could use an Ede. Victor ram but I think it would need some porting, even at that rpm. More plenum volume for sure.
X2 on the Edelbrock for single four. I think I'd go with the Vic R 4500, again, because fo the rpm. The new(er) Weiand TeamG is a really decent intake as well.
Is this a tall deck?

Is it me or does 377cc sound awfully big for a 800HP?

Originally Posted by gn7

is it me or does 377cc sound awfully big for a 800hp?

x 2!

Originally Posted by gn7

Is it me or does 377cc sound awfully big for a 800HP?

Especially if he's looking for power @ 2700 rpm

Originally Posted by gn7

Is it me or does 377cc sound awfully big for a 800HP?

I totally agree. The 377 has a 2.300 valve and is a big, high velocity, super good mid-lift flow head made for BIG engines with limited lift rules or big marine engines. The 357 would be a much better head IMO. Heck, even the 335cnc would work just fine.

Originally Posted by MACHINEHEAD1

Yes 10.2 deck. If it makes more than 800 Im ok with that. The head selection was based more on the lower lift flow numbers. A well designed head like these will still fill a 580 incher down low. Testing has showed that even the bigger AFRs dont hurt even 502s. A
335 AFR Vs a 305 AFR on a 502 (250ish SR) showed minimum TQ loss down low (3500) Like 10-15 lbs if memery serves, many years ago.
Anyway, Ebrock with porting and plenum spacer. The heads will have a little room to grow cubes in the future. Im a fan of running the smallest head I can get away with, but in this case would like to go as big as I can without making it soggy. Its 580+inches for shits sake!

I can see a 335 on a 502. But no matter how I look at it, I see a 800 HP goal. Thats 800 hp worth of air. Now you can do that with 355 inches at 9000, or with 632 at 5500. makes very little difference. Not to many 9500 rpm 355 cid nascar engines using 377 heads.
I understand the low/midlift idea. And if its cammed correctly I guess it can and does work. I was just curious. Seen bigger engines make more power with far less head. I have never taken this approach, I know others have. the beauty of a boat is, it never asks you to tow a trailer up a long steep grade, or cruise at some rediculously low rpm, shallow throttle angle, while dealing with the drag of 75 mph on the freeway.

Originally Posted by MACHINEHEAD1

Yes 10.2 deck. If it makes more than 800 Im ok with that. The head selection was based more on the lower lift flow numbers. A well designed head like these will still fill a 580 incher down low. Testing has showed that even the bigger AFRs dont hurt even 502s. A
335 AFR Vs a 305 AFR on a 502 (250ish SR) showed minimum TQ loss down low (3500) Like 10-15 lbs if memery serves, many years ago.
Anyway, Ebrock with porting and plenum spacer. The heads will have a little room to grow cubes in the future. Im a fan of running the smallest head I can get away with, but in this case would like to go as big as I can without making it soggy. Its 580+inches for shits sake!

It's 580" turning 5500-6000rpm max.
It doesn't matter how many cubic inches it is, it matters how much air it's moving.
Your 588 at 6000rpm with a 240* cam only needs about 380cfm @ 100% VE. Look where that is on the flow chart for the 377's. That's at about .500" lift. Can you guess what then port velocity will be at .500" lift? Not much. That's at 6000rpm! You can go 230* and the airflow demand goes up a little but the head is still going to be a dog. The only way to change that is to make the cross section smaller or raise the rpm. The 335's flow 385 at .600" and have plenty of low lift flow.
Cammed correctly, I GUATRANTEE you the power under the curve is going to be much higher for the smaller heads. ALL AFR heads focus on low lift numbers, so you can't go wrong there.
Here's a quick comparison "guessing" the port cross sections, we'll use 3.4 sq in for the 335cnc, and we'll use 3.8 sq. in. for the 377cnc. They're probably pretty close. Based on advertised flow numbers, here's a velocity comparison between the two from .200 to .700 lift

335 / 377 (FPS)

.2 115.7 / 111.1
.3 169.4 / 164.2
.4 214.6 / 207.2
.5 248.5 / 241.3
.6 271.7 / 262.1
.7 285.2 / 269.7

Throat velocity

335; 2.300 @ 90%= 3.27sq. in. @ 385cfm = 282 fps.
377; 2.300 @ 92%= 3.43sq. in. @ 385cfm = 269 fps.

Ideal min. area for 588 @ 6000rpm = 2.87 sq in. @ 385 cfm = 321fps.

Bottom line is, there's really no reason to put 377cc heads on this engine. Even the 335's provide more than enough air in all aspects. Both heads at their respective lifts have more curtain area than the min. throat area. The numbers are all just for comparison but they do show the trends.

Originally Posted by WETTE VETTE

Since you are running a 25' Daytona I'm guessing its a Bravo style drive. If that is the case your true operating range will likely be 3000 RPM and up. Even if it made huge torque at lower RPM's you couldn't really use it because the drive will be the limiting factor. That being said the 377's would be OK, but I must agree the 335's or 355's would be better. I run a 600" TR motor in my WPM cat and it pulls to near 7000 RPM with a ported Dart TR with 1050's and massaged Dart 355 CNC heads. Power and response is very crisp from a 3000 RPM cruise and up which is where most of these type of boats really need it. If 800 is truely what you are looking for I'd stick with a single carb and keep it under the hatch. However I do like the look of a TR under the hatch!

I am always a little confused by the thought of huge torque in a performance boat. specially one that isn't considerably under powered. When I think of huge torque numbers, I automatically think WOT. How else do you make huge torque numbers. Part throttle, 3000 rpm and 750lbs torque? I don't think so! So, ifn the numbers are genereated at WOT, how liong does any well powered boat remain at 3000, or 4000?
So back to the ports. At 3000 or 3500 PART THROTTLE CRUISE, the port is a loser. Restricted air flow due to restricted throttle setting, plus the low RPM= lazy ass port. I would be more inclined, but not by much, if the OP said the throttle would never be partially opened and always ran flat out, max RPM.
WOT torque @ low rpm has always been a mystery to me in a boat. I have a difficult time visualizing 3000rpm and wot. EVER.

I agree with the single dominator approach if the power is in the 800 range @ 6000. The TR will only help to make the 377 port that more sluggish at part thottle.