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4K views 33 replies 10 participants last post by  DEL51 
#1 ·
4.625 X 4.375 pump gas. May do AFR377 or CFE. 6000RPM. Trying to get 2.35 valve in this thing.
What cast TR is out there? Or just get single 4bbl. Have the Snippers/II/Jr been dialed in yet? Maybe 780-810HP
and all the TQ for the most amount of time. 25 Daytona cruiser
 
#3 ·
The customer may want to run a TR. Just because. How was your TQ range. I normally pull down to 2700 to get a clean pull by 3000rpm on a 540. Were your engines at 600ft/lbs by 29-3000? I have yet to build a NA engine over 555 and all with AFR or Canfeild/ Vic Jr and 850 carb. These were maxed out and pulling vac.(1.5") at 5700 redline @ 730hp. Just need some thoughts and hopfully some dyno charts of 580-605 inchers on pump. Thanks for your response.
 
#5 ·
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?
 
#10 ·
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!
 
#11 · (Edited)
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.
 
#13 ·
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!
 

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#14 ·
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.
 
#16 ·
GN, 600ft/lbs rolls a 25 daytona over pretty good. It happens often, that you have to move the throttle to WOT momentarilly to
get the boat up on top of the water, from a stop. And usually right back to part throttle. A combo of prop C/L /prop pitch/ and loaded weight are huge factors on this boat. This is usually happening at 25-3500rpm (going to WOT for a second or two) when your propped for 105-115 MPH. A softer torque number down low helps the drive survive. This is just a combo I have been wanting to try to get the drive repair intervals down and keep the power up in 800 range. Steel, I do understand HP in airflow terms. Wanted to avoid using more expensive (rpm) parts. Cam timing can help the part throttle cylinder fill issues, while sacraficing some top end. I guess it is like a Top Cam
Iron Chef kind of thing. If your presented these parts what type of weird cam can you come up with to impress the customer.
Once this customer gets his feet wet, Im sure we may go blower. Keep the carbs from the TR and the 377s. If this was going to be his last engine in this boat I would go for the 355s. I definitly dont have all the answers for this motta, but Im glad we are talking about other things besides the intake. Nice charts Steel. Sleeper weres your charts!
 
#17 · (Edited)
I totally understand. If I was disagreeing I would tell you the ignore the port size. But the importance of WOT torq @ 3000 to me seems a non issue compared to throttle response and drivability at part throttle 3000.

Making a big deal about 750 lbs of torq @ 3000 WOT and tossing a 5500 stall converter at it seems like nonsense. How do you ever make 750 lbs of torq with the setup. You can produce the same effect that the dyno did. You'll blow thru 3000 at the hit. Like a typical performance jet. You hit the throttle, and what it makes at 3000 is pretty useless.

Maybe a 25 Daytona with a out drive is mcuh different. But it seems hard to believe you can stay anywhere near 3000 for very long with the throttle pegged.
Just seems to me, the aspects of the engine at PART THROTTLE and 3000 are way more important, than WOT at 3000. And I can't see how you maintain decent velocity thru a port that large at part throttle.

Look at the 750 HP LSX in the other thread. Gaurantee the ports are anywhere nea 377. And the heads are no where maxed out.
Its not a engine size issue. Its a air requirement per HP, regardless of the RPM it occures or the engine size to develop it. Large slow engine, or small high revving engine. The air requirement isn't alot different. No 700 hp 454 needs a 377 head. I just don't understand why a 700 HP 600 incher does.



 
#18 ·
Well I can tell you with 600" and 355's from a 3000 RPM cruise when you go WOT it goes to 6000 in about one second and 6500 comes a couple of seconds after that. No throttle response issues I can see. Maybe the port is "lazy" at the 3000 RPM cruise and the two 1050's aren't in their there element, but when the hammer falls it doesn't matter because the big motor eats it up! Also a good tuner can do wonders with dockside manners. If the lazy port at 3000 is bothersome kick you cruise RPM up to 4000 and enjoy! I think the 377's are more than you need for 800 HP out of a 632, but they will allow room to grow if the owner either wants to add a blower or build a higher RPM NA mill in the future.
 
#19 ·
GN, I was sayin 600LBS at 3000. And the prop will bite that low and will take WOT. Is this what you are talking about in your last thread? Or did I miss something? Sometimes at Westech, Steve will perform some low rpm pulls, step pulls, set and wack it pulls. I have gathered alot of data on this particular boat line. Ive done my best with a wet peice of paper and a pencil (pens dont work) and fed Steve the basic gauge readings from on water testing. It beats the dyno up but it helps develope new combos. Just trying something new. I would like to see more posts and hopefully dyno results from REDROCKET. Seems he has built some bigger inch NA stuff than I have.
 
#20 ·
Wette Vette, I agree with what you said about the bigger mottas eatin it up. A little lazy is hard to feel in these types of boats.
They are lazy. You just feed 1 more click of throttle. A 540 with 700lbs and 730hp in a Daytona is awsome. To be honest, I would be willing to sacrafice a little bottom end for that sweet mid-top end pull. In this boat the cubes will make up for it. I understand this mill is going to be a comprimise. Just looking toward the future.
 
#22 ·
Wrap your head around this. A stock 25 Daytona with a 24'' prop and 425hp will need to go WOT for 7-10 seconds to even get on plane. And top speed at 65. Now prop it for 115mph. The Mag HO will sit almost still at 1400rpm WOT till something breaks. You need 600ftlbs, right now, to get the boat to roll over with a 32" prop. Once its up your good, and can pull WAY back on the throttle and maintain a happy50mph with 30% throttle. Next step is 40% and 70mph. Dont cruise well 50-70mph. Your gettin pretty deep into the throttle 40-50% and the thing is perched for serious accel.
 
#23 ·
I'm not saying you don't need 600lbs to plane the beast. I'm saying I'd have to see you pin the throttle and have it hold anything near 3000 for any amount of time. IF it was me, I would port the thing for the HP/RPM goal, not the CID. The CID is a static measurement. The CID/RPM is the air requirement. A 600 incher at idle doesn't need a TR and twin Doms. A one barrel solex off a VW will do the job just fine.
The max torque of that engine is not dictating a 377 head regardless of where the max torque occures. The RPM and CID make the requirement. You can make the max torque that engine will make, with its 6000 rpm goal, with a much smaller head. What the engines requirements are at max torque are considerably less than when its at less 6000, and the head is too big for that.
WettVette turns his 600 incher 7000 and has a set of 355s. How can a 588 at 6000 require more? Just curious.



 
#25 ·
Fod for thought and a reasonable comparison:
TN Youngblood's 540 makes an honest 850hp at the crank, observed, on a 100* day with 90% humidity. That corrects to an easy 900hp, 63-6400rpm. Now granted, it has a lot more cam than you can run, but the point is, it did it with little 316cc heads. Less cam will require more airflow for equal VE, but those heads were ported purely on a velocity profile basis, given the bore/stroke/and desired peak power rpm. Airflow (cfm) was never a consideration until after the velocity profile was established. That's all I look at when chosing a head for an application. Also, boost doesn't necessarily mean bigger heads. The constant I use for the port profile only changes by 2% with every bar of boost.
 
#29 ·
This is getting a little off track. I guess its not much more money to go 605in and 6500rpm with raised HP expectations. But I do like the feedback from all. Steel, I would suggest starting a new thread about growing the port 2%per bar. It seems it would make boost pretty quick with that kind of restriction, but not move alot of air. Something myself and others might like to hear your views on. Maybe some NA dynamic air speed theories, piston postion Vs. air speed/cam event. Big port/smaller port Vs. cam event for max cylinder fill with a head that is too big. Maybe Straub could chime in about a crutch type cam.
 
#34 ·
Steelcomp,Your inputs regarding port volume, valve size, rpm,etc are great! This winter we should start a thread regarding the basic designs,port volume, valve size, etc. Something that will give the average gearhead something to gauge their current setup. I am speaking of generalities and not direct head comparisons.I know I would benefit from this. Thanks,DEL51.
 
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