intakes
 

for a stroked bbc with iron heads roller cam i have a dart intake single plane but it seems a dual plane would be better what kind of experince do you guys have on the dyno with these 2 styles of intakes never will see over 6000 rpm please help trying to get the most out of my setup

The HP500's use a Dart single plane and that is what I am using.

I use edelbrock torker 2 single planes mostly due to deck clearance. Works fine over 2000 rpm.

intake
 

what heads are you runing.and what kinda flow# on the heads .does the intake flow more cfm then the heads. darts are one of the best intakes out of the box

i have stock rect port iron heads dont have any flow numbers but was thinking of putting larger vavles in should i or shouldnt i thanks bo

intakes
 

if you are building motors i would chang to aftermarket heads flow is power

cant afford heads thats why i was wondering if the larger vavles would help

The Dart is the best out of the box manifold for the price out there right now. I'd keep it.

If you ever do any other upgrades, like heads, etc. later you're already set with your intake.

DAVE

Intakes
 

If you will never see 6,000, a good dual plane intake will improve low end a lot and improve most numbers up to 5,000-5,500.
Bigger valves here will not help much. Good pocket port will show more gain. Also, notch the block-it really does work!!
If you will send me your cam specs, I will try to be more specific on what I think you should do.:D

hey blown 1500 rember when i told you about my cam you were right i called comp cams today they said they would take care of it under warranty preety cool they also said when using an after market fuel pump to use a bronzed tip push rod again just like you said my cam specs are intake .591 exh .601 dur a .50
intake 222 exhaust 230 at 112 lobe sep hope you can help bo
also the block is bore notched

Hello carreraboat! I see that you are relatively new. Do you have a 30' Carrera with twin engines? I knew of a few guys who have owned 30' Carrera's on Lake Michigan. I have riden on them several times. There are a very HEAVY boat, they sure ride extremely well in the rough! I even remember a guy who had a 24' Carrera that was very fast and nice.

As far as intakes go, I would also choose a dual plane intake. A good Edlebrock Performer intake or what they call an "Air Gap" dual plane intake would work very well. Dual plane intakes give you much better usable mid range torque and still gives you enough to kick it up to about 5000-5500rpm as blown1500 has said. Adding larger valves would give you about another 10-15hp. Are your heads bowl/pocket ported? Bore notching the cylinder block bores would add about 30hp as well but must be done properly and carefully. You could add the larger valves if you have the heads off the engine already, but I wouldn't go to the trouble and expense of removing the heads just to install larger valves unless you plan on doing a bowl/pocket port and a good valve job.

Bowl/pocket port $175-225
3-angle valve job $120-140
install larger intake valves/seats (stainless one piece) roughly $350 per engine
aluminum dual plane intake manifolds $195 each or so

Here's one thing you could try without much expense: Buy an aluminum dual plane intake manifold. On a decent day run your boat with what you already have (Dart intake) then on the same day if you can, install the new dual plane intake on your engine and give it a go. The dual plane intakes are cheap enough to do a test like this and then sell it if you don't need it. You may not get what you paid for it but at least you will KNOW what works best for the weight and application of your boat.

blown1500 can help you out if you need help. Best wishes :)

Your cam is not too far off, especially with the head work and intake swap. You could go up a little and still have a good idle and bottom end power. I'd probably try the Crane 139741 hydraulic roller. It has never let me down! You will loose on the bottom end, but you will pick up a lot at 5,000+. You must choose where you need the power the most. If you cruise at 2,500-3,200 a lot, you may want to keep what you have for a cam-just do the heads and intake. For more specific help, call me at 704-574-4020. That is a cell and I have it most of the time.

sorry guys i really apperciate your responce i have been following these boards for about three years everytime they change i have to re register i am a carrera dealer here in new mexico i am a 1 man operation . i really appreciate all your info you guys have tried just about every combo out there i guess i try and learn from other peoples mistakes . my boat is a 24' with a light lay up i have a shorty drive we boat on lakes hardley ever see big water . try to go to havasu as much as possiable . hey kaama what do you and blown 1500 do for a living my main gig besides the boat thing is i am a tool dealer for matco. i really appreciate the info any other things i should try i look foward to your input
bo

Who---ME?
 

I'm just an exterminator turned offshore boat freak. I kill bugs for a living, but I grew up around boats on Lake Michigan since I was a kid.

And well, blown1500 is the real Offshore Hi-Performance Engine Builder Guru Extrordinare with an engineering degree. It's what he does for a living and when it comes to marine performance grade engines, (as Foghorn Leghorn would put it) I have quickly learned-----I say I have quickly learned that boy-----I say that boy will talk circles 'round you, me and about 1000 other people on this board even with his tongue blowed owff and half his mouth taped shut son! :D

carreraboat,
if you take an open plenum, dual, and a tunnel ram in a side by side comparison with only the intakes being changed on a motor on a dyno, at 3500 rpm's, the torque will be with in 5ft. lbs of each other. at 4500 rpm's you will have 10 ft lbs. more torque with the open plenum than the dual and 15 ftlbs more torque with the tunnel ram than the dual plane. at 5500 rpm's the single plane will make 15 ft lbs more torque than the dual and the tunnel ram will make over 20 ft.lbs. more torque than the dual plane.
keep in mind that low rpm use such as docking will be better with a dual plane due to a higher vacuum signal to the carb. if your not having a problem now than that doesn't matter. single planes intakes are also more sensitive to carb CFM size changes.
if you want 30 more hp per engine, knock off the casting ledges, machining seams,and casting seams below the valve seats with a die grinder, smooth out and widen the short side radius and clean up the bowls. that is the main area of flow restriction in the heads. all it will cost you is some sanding rolls. you don't need to pay a pro to do it. it's very easy. it is the best bang for your buck. i wouldn't waste money on bigger valves. if the chamber walls aren't relieved to accomodate the flow increase of bigger valves, they can actually cause a flow restriction from what you have now. if docking isn't a problem i'd stick with the dart manifold as well.
these are real world #'s and aren't guesses by the way.
good luck ;)

Exterminator ehh kaama? Does that make you a PCO? I find that interesting because of what I do... make products for the pest control industry. It's not just a job, its an adventure!! We even have a huge cock roach colony. Exciting don't you think?

BT :cool:

that get's the RAG'S :D :D :D

thanks excal i think i will do just that !i really appreciate all of your guys advise
bo

excaleagle42,

Hmmm... not sure I totally agree with that although if that is what you have seen on a dyno I guess I can't argue with your experience.

Not trying to spilt hairs here, but here's what I have experienced a year or so ago just for a gentleman's argument sake:

A friend of mine "DanB" has a 509" naturally aspirated engine that he used a Crane 236*/244* on 112* lobes, 9.0 comp ratio, Holley 950cfm carb, with non ported Merlin cast iron 308cc heads and on Tyler Crocket's dyno it made 563hp @5500 and 620 foot pounds of torque @3400rpm while using an Edlebrock "Air-Gap" dual plane intake manifold.

My 540" naturally aspirated engines use the basically the same cams Crower 236*/244* on 114* lobes, 9.2 comp ratio, Holley 830cfm carbs, Dart pocket/bowl ported Pro-1 aluminum 310cc heads on Tom Earhart's dyno made 630hp @5400rpm and made 625 foot pounds of torque at 4500rpm while using a Dart single plane intake manifold. Torque was 583 foot pounds @3500rpm.

Again this is a 509 vs a 540! That's 37 ft.lbs. difference over the 540 of and at more of a usable cruising rpm range.

thanks i really appreciate your input gotta decide what to do gotta get the most out of of single motor package

Kaama,
i think we we are comparing apples to oranges. your motor and DanB's are really different. if you take the same motor with everything being the same including the lift/ duration and only changing the LSA of the cam, the engine breathing, idle, and power range will be different. plus your talking about, crank stroke, rod ratios, different piston pin heights, pistons, head gaskets, heads, ported and unported, runner volume, chamber volume, quench area, valve sizes, heads, intake manifolds, compression and carbs. then the variables that you didn't mention were valve lift, lifter type (bleed rates?), air cleaner, and the size and length primary and runner of the exhaust used on the dyno. they weren't even the same dyno.
years ago, a dual plane was much better for low end and a single plane was much better for top end. modern intake designs have bridged the gap slightly with better flowing high rpm dual planes and single planes with better low torque. if you get a chance to change intakes alone on a motor on a dyno, you may be surprised at 3500 rpm's. my own feeling is a dual plane with a notched divider is the best of both worlds for almost any marine engine for pleasure use.
:)

Excal, does the stock mercruiser alum dual plane intake fit your description of a notched divider intake? If not, what is that?

BT :cool:

BT,
the notched divider starts life as regular old dual plane intake but it's modified with a die grinder to notch out the divider under the carb a little. notching the divider helps the higher RPM breathing for more HP and won't hurt the very low end torque as much as an open plenum would.:crazy:

excaleagle, Sure, all parts make a contribution to the power of an engine and I think most will agree that the heads and cam of an engine pretty much determine the major power source of an engine. The cam comparisons are practically identical---mine were Ultradyne Cams which even have more aggresive ramp speeds, my heads even flow better than his. The comparison of our engine components are pretty close and yet his engine wasn't built up as much as mine and he STILL beat me in the mid range torque curve area! The point I am trying to make is, a 540 should probably make more torque over a 509 around 3500rpm---right? I mean, lets face it; with NEAR COMPARABLE PARTS a 540 should beat a 509 down low.---and I am sure I would have if I was using a dual plane intake! I thought it was pretty much common knowlege that bigger cubed engines make more power down low, and with my 540 vs his 509 I should have had the advantage over him with bigger cubes and better flowing heads---but I didn't! I really believe it is because of his dual plane intake vs my Dart single plane. On the dyno, both engines used tubular dyno headers. Do you not think my 540 should have had MORE torque at 3500rpm than his 509? But instead it's just the opposite---not even close! BUT, if I had a dual plane intake on my 540 vs the Dart single plane, I am quite sure I would have at least turned that 37ft pound figure around to my advantage at 3500rpm or there about.

With all components remaining the same, let's say (for arguement) my 540 and his 509 make the same amount of torque at 3500rpm. And if I removed the Dart single plane intake from my 540 and swapped it with a dual plane intake you don't think I would see much more than 5ftlbs of torque difference @3500rpm? Well, I guess I am truely getting older and getting BEHIND the times or something. Perhaps the dyno comparison with my 540 vs his 509 isn't a fair one. I don't have a dyno, but boy I would sincerely like to see a back to back comparison on a dyno with an intake manifold swap from a single to a dual plane!

My boat is a 32'A/T with the 540's in it. Because my HP to weight ratio, I can get away with a single plane because torque isn't quite as crittical for me. I guess I was just really impressed with his 620ftlbs figure @3400rpm vs my 625ftlbs @4500rpm. And I know there are a lot of other variables that you have mentioned, but SOMETHING in his 509 was making a lot more torque than my 540, but perhaps you are correct. :)

Excal, that divider notching sounds good. I haven't installed my intakes yet and am looking for jobs this weekend. My intakes are stock alum dual planes off 502s. Can you describe how to make this change? I'm getting good on the die grinder as I just finished up the bore notching last weekend. :)

BT :cool:

BT,
just grind out one inch down along the entire divider that separates the odd bank of cylinders to the even bank.

.

Thanks excal, sounds simple enough. I'll give it a try. :)

BT :cool:

bt, sounds like you're begining to like anything with the word "notch" or "notched" in it. ;) :) :D

he can add another NOTCH to his belt.

Yes, notching is good. I believe I am running out of things to notch though. :) Really I am turning into a die grinder junky. Ain't much you can't do with one of those little buggers.

BT :cool: