BBC 555 dart vs rpm intake
 

Ok I can imagine this will go both ways with dart single plane probably being the ticket by most however thought I'd post this. These are 555 builds aiming for 700 hp. Heads will dart 310's opened up to 320 plus int runners and will flow to their full capacity being ported by jim valako. So let's say they will flow close to afr 325 cnc heads. (I already have heads). I'm running darts on my 496's however felt confident I could have went daul plane and been fine. New 555 builds will be propped for 5,700-5,800. Same as my 496's.

Interestingly enough I called afr and talked to a long time customer service rep and he suggested their 325's which I figured as much however he really pushed the rpm air gap for these builds. I would imagine due to the rpm these builds will run at. I see there are a lot of single plane darts out there on smaller cubic inch engines that don't necessarily belong in my opinion.

I guess what I'm wondering is if anyone is running dual plane air gap intakes on 540-565 cubic inch builds. Personally I had planned to use the the dart single planes with these builds matched to the ported dart heads however after I talked with the afr rep I second questioned myself. Cams are solid roller 647/637-244-248 on 111. Carbs will probably flow an honest 1,000 cfm. (Pro systems). Will try 1:8 rockers on the intakes while on dyno to compare pulls. I just may do a quick intake swap on the dyno also unless I get talked out of it.

Boat is a 32 and weighs around 6,700 pds.

Most my boating is cruising at 2,900 or wfo however I do like hard acceleration when pinned at 2,900. Would be interesting to see torque curve results on both to be honest.

Put it this way, it has been proved ob 400hp and change mild 454's the Victor JR makes more power from planing to WOT, and it does so with way better fuel distribution cylinder to cylinder. Most recent was by member Apollard with great testing techniques, WB02's, and data loggers. His RPM manifold distribution was so bad, he doubted the WB02's and replaced them.

Cubic inches changes things is a hurry. Mild / to healthy 350-383 small blocks with I/O's like the RPM better.

Edelbrock SV-565

That's interesting.

Single plane enough said. I'm pulling my remaining dual plane this year. I have ran 1 dual and 1 single for years. They were always in sync RPM wise and throttle position wise. I thought there was no difference. I then tuned the engines last year and the single plane pulls a couple hundred RPM's more at the same positions and at full throttle. I will admit I was wrong.

What kind of ninja tuning did you do? That's awesome you did side by side no BS comparison.... I knew if I asked Jim he'd say your definitely gonna make more power with single plane. Works out well for me cause I have a number of darts anyway. i was shocked when calling afr direct what they recommended. Not even sure what possessed me to do so but did.

Try both and find out exactly what the difference is. You can never have too much info. Someone must have one you can borrow. I believe afr recommend a dual plane to me as well. I think it's the old generalization that at "lower" rpm single planes aren't as good. I'll bet any sales guy would say you'd be better off with a dual plane at 5700rpm. Most of the engine builders would likely disagree with that however. I went with a single plane on mine, but always wondered what the difference would have been.

Tony MAMO, if still at AFR would have fallen over if he heard other reps say this.

Listen, I'm all about theories and thinking about things too, but there are some tried and true's and this is one of these. But heh, you can't force someone to listen.

Your right. Besides its always fun to try different combos etc. I've been doing that most my life. Some went south some went extremely well. I'm fortunate where I am able to dyno as I do most the work myself and not bothered and typically given more than enough time to do what I need or want to do. It never fails though I always learn something and that's the key and what makes us who we are. If it wasn't for already having the dart 310's already dressed I was going to try the afr 300 cnc oval port on these builds. Losing some hp up top without a doubt but fun and different builds.

The thing is that as far as most run of the mill salesmen are concerned the tried and true is that single planes don't work below 6k. They are almost guaranteed to recommend a dual plane for any engine once you tell them 5700- 5800 max. To them the experimental theory is that you would consider running a single plane below 6k. I'd like to see an actual comparison.

Ya the call was a spur of the moment thing but like I said even after questioning the rep about 3 times I just let it go and thanked him for his time. Rookie made a pretty good point and experiment with literally running each under the hatch with little to no difference until he did some engine upgrades etc with the single plane clearly making more power.

This kind of throws away engine building 101 in my opinion yet proven to work. Still interesting with Rookies test. Difficult to not take advantage of actual knowledge and outcome. Single plane it is. SB had interesting points about the rpm that I was not aware of.

While on the subject anyone run or have any input on Darts dual plane? Pricey unit.... They do look well designed though,

quoting myself from another forum years back:

So I now know I'm going with single plane. Continplating the Edelbrock sv-565. Any others with experience with them on a 555? Super victor? Victor Jr.? Profiler Sniper? Dart? Merlin x? What ever intake I end up with will end up at valakos to mate up and flow with heads.

4500 flange to fit 1050 Dom

Just put a tunnel ram with 2x4's and be done with it.

That's Exactly why I have 4 Holley 700's on the shelf just in case. Was my original plan.... Thought I'd keep it simple so ended up getting another 1050 to match other. Build one of each? Dyno both.

Maybe just look for a couple AMC Pacer engines and be done with it.

Too small for a big BBC. About right size for small block. Yes, I know. 2 carbs on a tunnel ram.

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Going in this

FWIW.

Sometimes, when you have a 570 inch big block, with ported heads, and goodies, the 30 year old "smaller is better" train of thought, goes right out the window. What applied to 454 build ups many years ago, doesn't necessarily apply to a modern day big CI engine. Back when guys thought slapping on a 1050 dominator and single plane, on a 8:1 truck engine was a good idea, and quickly learned that it wasn't. But, a hot 565ci in an offshore boat, would have no business with a dual plane intake, in my opinion.

here's a 572ci engine, making 800hp at 6,000rpm, and 750+ ft lbs of torque at 4500rpm. You can see what choking the engine with a 850 carb and fairly restrictive GM intake did, compared to a Profiler Sniper jr and dominator. Talking 50+hp gain from intake and carb at peak, and still killed it in torque at the lower end. Going smaller doesn't always mean more torque. Would the 850 carb combo be more crisp in a street car cruising around town with a tight converter , probably.

Thus my airflow info on post #13 above. Sheds a lot of info + mental images in a millisecond when looked at it this way.

While generalizing, David Vizard pretty much says a big block

500-525HP max torque build, a dual plane with divider cut down is the choice.

525-600hp, he calls it a gray zone. He says either will work.

600hp+, single plane .

We just dyno'd a 588 with an old set of dart 355 heads edelbrock tunnel ram 2 1050's and a cam better suited for a blower and it made over 900@ 6300 840 ft. Lb's torque. From 6300 rpm to 6700 rpm motor only lost 5hp. Tunnel ram is definately the way to go but it gets expensive. If you plan on a single plane intake the best one available is the Sv-565. Sniper would would be a close 2nd...

If you dont mind me askin, what were the cam specs roughly? Ive got a buddy thinking about going tunnel ram on some 572s

I'll get them for you tomorrow. The were around 250-260@ .050 .680" lift 114 lsa. We had another cam and intake / carb to try on the dyno bud the carbs were so bad on the tunnel ram we spent the whole day getting the carbs right.

nasty

Cool, thanks !

Wette Vette's 598 with Dart Tunnel Ram and 2 x 1050's ran on pump gas and went 126 mph in a single engine cat.

Good find. Was that an article from magazine or website? I'd like to read up a bit more on it. While surfing and researching the subject from different forums etc I do hear a lot of positive feedback on the sniper jr. I've continplated the tunnel ram with dual carbs and have numerous sizes to try but have to be honest I'd rather stick with the single plane. Would it really be worth the extra perhaps 18 plus hp at the given rpm I will be tuning for?

Tks for your post.

Dart Tunnel Ram on a big cid marine I/O motor turning somewhere from 6000-6500 will make you schit yourself. Will gain from typ vic r / victor 454-r from say 4k and up.

Just like regular intakes, a single plane is not like another single plane and a tunnel ram is not like another tunnel ram.

Richie Zul used to use them alot.

Ya I've talked to valako about some here a while back. He of course has tunnel and no doubt makes more power. Ideally I'd like to be propped for 5,600-5,800. So with that said I would like peak hp within somewhere in btwn. No more or no less.

So with that said what would you expect the difference in power to be? If I was gonna be spinning 6,500 plus I'd without a doubt go tunnel. But let's look at where I'm gonna spin the props at. With a ported and matched single plane vs ported and matched tunnel both with right carb set up. How much power diff at 5,700? 18-25 hp Maybe. Torque curve? Gotta call valako tomorrow and get his input also.

Its not uncommon for a tunnel ram to make more low end as well as more peak power.

Anyone happen to know if Bob is correct with these specs. I've heard this cam works well in bigger cubic inch NA engines also. I always thought the 850 sci was the same cam as the 1075 sci. Any insight on this?According to bobs comment at the bottom threw me off a little.

I just tx valako to see what he thought regarding tunnel with my opened up 310's. They typically end up 320 plus. Ya the tunnel ram definitely gets a little pricey especially with two but so does alcohol.

This was not a cam from Bob. The motor started out as a blower motor. Intercooled 10:71 made 1050hp removed the blower and dished Pistons added tunnel ram. Re-used carbs cam everything. Had custom Pistons made to match the weight of the old Pistons. Did not re-balance. The motor had maybe 75 hours on it and to tell you how old it was the Dart Block number was in the 200's. Motor made about 125 hp less without the blower...
Tunnel Rams work much better than a single plane they will always make more Torque if they are tuned properly they will make more horsepower. To properly tune a tunnel ram you really need to run a bunch of cams through the motor. You can run all the computer programs in the world but when it comes down to properly tunning it you have to spend some money and run more than one cam through it.

1075
 

Meant to attach this earlier.

I have no doubt they make great power. I've seen it first hand also. I realized the cam u used wasn't one of bobs rather curious if the above post is correct for 850-1075 cam?

Valako got back with me on his build and its 785hp@6,000

I've noticed you have made this statement, a few times in this thread/build discussion.

When you say "opened up", that doesn't really mean anything to anyone for the most part. Adding "volume" to an intake runner, doesn't mean its going to flow more air. I can go in there and grind out 20cc worth of material, and ruin the airflow.

The measured CC of an intake port, really doesn't tell you squat. It doesn't say anything about the airspeed, air flow, RPM band, or anything concrete. Things that matter, are the shape of the port, the throat diameter to valve relationship, pushrod pinch, short side, long side, CSA, and so on.

You can have a 300CC port, that has much worse airspeed/velocity, than a 340cc port. You can have a 340cc port, that flows less air, than a 300cc port. Generally speaking, you want the smallest port, that isn't giving up anything in flow to a larger port. I see so many guys building their combos around intake runner "volume", rather than focusing on what the port is , or isn't doing.

Smaller ports are typically favored in marine engines, because most marine engines, are not using high lift camshafts. Lets say for example, you had a 320cc head to start with, and a 630 lift camshaft. IF you were to maximize this head, you might focus on the valve seat job, throat area, etc, to improve low lift airflow. Generally, these mods, don't add much if any "volume" to the port. Now, lets say, you decided to up the cam, to something with .750 lift. That stock 320 head, might hit a wall airflow wise. Maybe the port stalls out around .650 lift. Now, you have to go in , and modify the port. Possibly working on the short side radius, port entry, and so on. Now, the port grows to maybe a 340cc. You're target wasn't 340cc, but it ended up there, in order to achieve the airflow gains. However, doing those mods, with a .630 lift cam, might not gain you a single hp, because you simply aren't lifting the valve that far to take advantage of it.

Where modern heads are good, is in that, they now have smaller ports, that can actually flow very well at higher lifts, than stuff we had decades ago. A stock GM iron rectangle port head, had 325cc worth of volume, but didn't flow squat in stock form. A modern 270 oval port aftermarket head, will not only move more air thru the port, it moves it faster. Thats the benefit.

The Dart 310 Pro 1 is a good casting. In the right hands, it can flow very well. I know valako can make that head flow and make some really good power for what it is.

Where it gets even more interesting with port sizing is with a rectangle port head. Air does not flow through the corners of the rectangle. So what does that mean? Simple port size really means nothing unless you are "class" racing. And then there are ways to cheat around the rules. Example: mill the chit out of the intake flange on the head. This shrinks the volume of the intake port and allows you to go in and shape the port differently.

Since this is an intake thread I'll throw this out ther because some people tend to look past the obvious. The intake is an extension of the port in the head. If you have a head that has a port that is to large for the motor (and I don't mean cc wise) there is a way to get the air speed back up in the intake track it's simple. You use a smaller intake (the "old school" ones). The same theory works if you have a cylinder head that is to small for the motor you can use a larger intake to help fill the cylinder. For the OP's motor seeing as he has a 565 cu in. Motor and a "small head" I would use a larger intake like sv565 or better yet the new Edelbrock tunnel ram. The new one has a much larger opening on the intake runner than the old one...

Love rules racing ! Well, not all of them. LOL.

Plenum volume and runner csa and runner length of an intake manifold can make or break power on an engine quickly.

I think it's easier to 'over intake manifold' an engine than 'over head' it.

But, the more cubes you have, it can be difficult to get 'too big' on either.

I only mentioned finished runner size for those who may be curious. I wandered off a little from my original post. And yes I do understand flow and velocity. Been at it a while and worked along side valako and flowed many heads including some of my own. Thanks to my thread my builds have now slightly changed. Tks black baja for putting my original plan back in motion.

i hear what your saying yet not completely onboard with big or small heads when you take runner size out of the picture.