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STV_Keith

MAD EFI intake

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Kieth,

Saw your post on S&F and tried to answer the question with a question. Sorry. The BMEC stuff is how engineers measure an engines volumetric efficiency. The GP bike figure and like a 1000 hp F1 three litre is over 180psi. (thats the measurement they specify and I'm not totally up to speed on that) The closer to 200 the more perfect. Our pitiful 2.5s barely break 100, 120ish in mod form.

On to the SVS and Taylor front. I ran lots of side by side experiments with the SVS last summer. On a full mod motor and a 280 with 260 electronics. I've run boats with SVS's in the past and honestly was not that impressed. My testing this year was with the PCU in tandem with the SVS. On the mod engine the difference between the air horn and the SVS was, well, shocking. Tons of punch in places I never knew I had it. About the same top rpm, but I was turning over 10000 in the first place. Interestingly, when I first put it on it sucked. The fuel curve was for the air horn and to tell the truth it really ran bad. Then I tweeked the PCU after watching all my exhaust temp spikes and god did it go then. That is maybe why so many people have not had overwelming results. The fuel curve is totally different. To run the SVS on a Merc box is handicapping the SVS.

On the 280 the difference was noticeable but much more subtle. Kind of like adding 10psi of compression.

I know Wayne Taylor very well, have for years. Everything I've ever gotten from Wayne over the years, works. But sometimes too well! What I mean is sometimes I have to take a step back and think through what I've done carefully. His stuff is usually radical enough to upset my delicate balance. The difference is that noticeable. I am working with his intake on a project motor as we speak. The injector placement in front of the reeds is very favorable. The Merc motor doesn't fire it's injectors sequentially. By putting them before the reeds the motor will only take fuel when it needs it, not when it squirts. The result is crispness. Mercury didn't think this one thru all the way. Tony Brucato and I have had conversations on the subject and he is working on a spacer to hold the injectors between the slide (SVS) and the reeds. Wayne's intake is in it's second generation now and the quality is much better. He doesn't have to hand grind it so much. Obtaining this crispness is why you would want a very "correct" fuel curve.

I feel both products do work as they are intended but here is my word of caution. Both guys have there own ECU avalible. Don't sell the thing short and not go with the electronics. Merc ecu's are like a pong game compared to the new systems from Tony and Wayne. ( a pong game has an 8k memory, the merc ecu has less!)

Move up to the "play station 2" and then the result will be felt in your seat. Also I think they work better on the mod engines than stock 260's lets say, that stands to reason as the ported drag engine "needs" the extra flow.

Tom Johnson machines a reed plate/spacer for me that works real good on waking up a mild motor with the merc electronics. Worth about 100-200rpm with some noticeable acceleration difference. It is not like the "redirecting" work that some guys do to this assembly. It is simple and works, less than $400. I use this for guys that don't have the "bread" to do the SVS/Mad efi thing the right way.

I hope I don't bore you guys with this stuff. I write because in the early days I bought lots of stuff and some things worked some didn't. If I knew then what I know now I'd be much richer! Hope to spare somebody from going down the wrong road. The above products are both great things, but some tuning is required! cool.gif

Randy

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Bore us??? I am amazed and grateful that you take the time to share your vast knowledge and experience with us. I have been wondering te same thing, and I appreciate the detalied answer.

fish

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I agree this is NOT boring its GREAT INFO..

THANKS RP biggrin.gif

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Kieth,

I hope I don't bore you guys with this stuff. I write because in the early days I bought lots of stuff and some things worked some didn't. If I knew then what I know now I'd be much richer! Hope to spare somebody from going down the wrong road. The above products are both great things, but some tuning is required! cool.gif

Randy

Randy, thanks for your time to write that post. Perhaps we should take this to e-mail, but this is exactly what I am looking for. I'd think the others here might like to read it too, so that's your call.

I am looking for exactly what you said - someone else that has done it so I don't make the same (or worse) mistakes on my own road. That said, I've got a 2.5/260 full JSRE lake motor (not drag). Horn motor with his plastic reeds, angle cut reed plate, 1" spacer, dry stacked, etc. Also running the PCU.

I need more though, and have looked at both the MAD and the SVS, and really, can't determine which is better from a picture. smile.gif Looking for any light you might be able to shed on the subject relative to my motor.

On the VE thing, that wasn't even about this same project. I was just looking for a number for a stock 2.5/260 that I could give to a guy asking about the Merc's efficiency in comparison to a 4-stroke car motor.

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Kieth,

Since it looks like you have a motor that is similar to what we call a 1/2 port, would you see anything from the intakes? I think, and this is my honest opinion, if you really turn up the motor (9000ish and higher) you would see a "feel-able" difference. If you run it 8000ish or lower the difference would be hard to "feel" with out some serious seat/same-set-up time. I would suspect that if you hit the magic prop by chance the difference would be more than the intakes would give you....but with the best prop the intakes get better. Can you see where I'm going with this? If I had the hard numbers on your present set up I could be more accurate. RPM, MPH, set back, gearcase, stuff like that. The closer you are to maxed out (from what I think is possible with your equipment) the less we could expect from the change of intake. Some may ask why this is. Because I have found that on occation if you add a part like the intake, it makes the motor run in a different state of tune and enhances the boats performance to a greater than normal extent. Example: lets say the motor was a little fat. The box setting, or in this case the PCU, was a little conservative. Add the SVS or Taylor intake and the motor "cleans" up because your setting is closer with those parts. Magic increase in speed better than expected. The result was better because the set up wasn't optimised first. This is the most common thing I see happen, or if the PCU was great for the air horn and marginal for the SVS.....you can see where this goes.

I am not trying to talk you out of anything, just remember the more stuff you put on the harder to total sum is to optimize. Anyone who tells you different is making their residence on fantasy island. Opps, there went Tatoo running by blink.gif . I would love it if my advice helped you as it does nothing for my reputation to tell you BS. Let me know your present performance numbers and I'll give you some "real world" goals you could obtain.

Randy

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Again, thanks for the time to write your replies.

First off, the motor is soft. I've got one hole (#3) at 110#, while the rest are 126-134. Now, I am at 2100' here at the house, so that affects the numbers a bit, but #3 is definitely a problem. When it comes back from getting its new cover, the motor is coming apart and we're gonna diagnose and fix that problem. My guess is an out-of-round cylinder.

I've got the PCU pretty well tuned with the laptop as well. All the pots are at "0" except for the accel pump stuff. I'm not 100% happy with that off the bottom, but everything else is sweet. It typically runs 1100-1150 at cruise, and a little fatter (~1100) at WOT. The limiter is set at 9k, to keep the rings alive as long as possible but still have a screamer.

Because I'm going to limit the motor to 9k, perhaps the intake isn't the way to go. Once the motor goes back together this time, I will be taking it to Eric Simon's dyno to see where it's at, so I'll have more data.

Best to date performance is 105mph at ~8300rpm w/Mazco RE3-27. Have also run my "clopper" - ET looking chopper to 8900 for 99.x MPH. All on GPS. With my 28 Merc hump-back cleaver, it ran 100 at ~8100, 2-up, but only 99 with my RE3-29 Mazco at 7600 1-up again.

105 is the best this boat has ever done, between me and the previous owner. From what I read though, a stock 260 should run 112-115 on an STV, so I don't know WTF is up. Motor is on 6" setback, 1/2" above the pad. Ran slower with the same motor at 1/2" up on the transom, by a decent margin (10mph).

Since you call this a 1/2 port, what else might you suggest (since it's coming apart anyway) to enhance the 5500-9000 rpm range? That's typically where it is at WOT. I was already planning to have Dale Hill lighten the pistons under the dome in addition to what Jay did.

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Keith,

Just a couple of things for us to dwell on. The speeds you are obtaining seem low to me considering your boat, motor, state of tune etc. Even the altitude shouldn't be that much of a factor. I set the 141 deal at 1600ft so we are almost the same. Talked to B-Rad today and he mentioned that you've have a run of powerheads with low compression on some cylinders. This puzzles me. If the cylinder was far enough out of round to give it that much leak, you would think it would have siezed by now. Out of round holes don't dissipate heat for s*&t. What rings are you using and were they new? What piston style? I found that the PCU set a 1200 degrees for a peak temp really wakes it up, but with the weak hole I'd refrain from trying that just yet. All in all, the power loss at rpms above 6000 with the weak lung is probably less than 10hp. So, the question is, where is the missing 10mph? I say this because you have all the ingredients for a 115mph Pro Comp. I've got several guys running that fast around here. The fact that it runs better with the 27 Mazco than the 29 Mazco is interesting. I've never had that happen in 15 years of running RE 3's. There is something in that 27 and your boat likes it. Usually a 27 on your combo runs short of the 29 by 4-5mph. I'd almost say before doing anything we should run a totally different prop and see if the boat responds. I could send you one that I know will turn a certain result, then if it doesn't we look at the next thing.

Is the missing MPH just a couple turns on the PCU to get the exhaust temp up? Maybe, but I don't think its worth 10mph. Just a side note, I never had much luck taking weight out of the dome area. We do some in the skirt, but the only failures I've had were with thin domes. This includes taking material out near the back side of the ring area. When you turn up the wick, (you are running pretty safe exhaust temp now) the dome collapses. The way we have the skirt lightened, I never failed one of those yet. This is just an observation not gospel. Some guys have had good luck with the dome thing. Back to the boat....

If your cylinder is way out of round then that is a sure indication that the temps you've been running are way safe. After the repair and break-in you could go pretty far to 1200/1225 range. I run 1250 all the time but call me daring.. Race gas helps when getting closer to the edge. Honestly, because the hidden speed is still hidding, I would suggest we find it before changing intake styles. Then a true gain can be had from those parts. As far as mod-ing the motor futher, I'd probably refrain from that too. EVERTHING is in order to get the speed the way you have it... just need to figure the puzzle out.

If this boat was here and we had soft water, The first thing I'd do is try a prop that I know works to a certain degree. ( the mule props as we call them ) This eliminates that question...hence why I offered a prop to run. Then investigate the bottom of the boat. I'd like to know if you have a little dip or hook in the outside trailing edge of the sponson. It won't be big (1/16-1/8") but it can have a good or bad effect depending on where it is. We haven't talked about gearcases. What are you running? As you can see this is a process of elimination. But how would you feel if you could run 115 at will? I think it's there already we just need to figure out why it's not cooperating.

Let me know what you think..

Randy

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My goal with the boat is to top 120. If it will do that, 115 should be achieveable at any time with a prop to get there.

I have had a run with powerheads. When I bought the boat, it had a stock 2.4BP EFI on it. Ran a best of 97mph with the 29 RE3 at 7100rpm. Always seemed to hit a limit there. Tried a diff. ECU (A13) with no limiter and no change. Later that day, it took out #2. Upon removal, someone had rigged the boat with 1/4 ID fuel line, but because it was the marine grade, it had a large OD and I never thought to check it. Ran great to 7,100 or so, but that was it.

Tore it apart, (had 2 wiseco pistons in it, one was .015" over, the other was stock bore), had Ruck fix that hole and 3 others (one sleeve had dropped, another was one that the top had been machined off the bore, and one was the .015" over so Ruck fixed it all). He did the exhaust chest, I swapped to big rods, all ART pistons, he did some work on the rod slots, transfer ports, light flywheel, etc. Put it back together and it ran the same - 97mph. Compression was always down (110-115# across the board). We cut the heads 2x trying to get it to come up. Never did. 2 sets of rings, didn't help. Eventually sold it, buying a 2.5/260 with #4 burned.

The 2.5 is a 95 EFI motor. Had JSRE fix the hole, plus all the other work. The compression has been down on this one too. He's cut the heads once, from 33 to 31cc, and It's still at the 126-134 on all but the weak one. That one is 110#. It did come up from 100 to 110 when we put the tighter heads on, but it's still low to the rest. I've re-ringed that cylinder with another new set of rings once since the motor went together as well, no change. I'm running the Merc ti-rings, they were new when it went together originally. OEM, no aftermarket.

The motor seems to pull pretty well, but with the compression down, I'm sure it will pull harder when it's right. It will spin up to 8900, which is where I back out (limiter is set at 9000).

Regarding the prop, the 29 ran the best with the 2.4. It seems like the 2.4 just ran out of RPM, so the bigger the prop, the faster it would run. It pulled everything to 7100 or so. Of course, all I've had is the 29, a 24 chopper and a few loaner 26 ET's, etc. The 2.5 will turn my 24 ET look-alike to 8900, turned a 14 3/4 x 26 ET to 8800, turns the 27 RE3 to 8400, turned a 28 Merc 4-blade cleaver to 8300 and turns the 29 to 7800 or so. Kinda feels like if you can get it past the 7600-7800rpm range, it just keeps pulling. If you don't get there, it won't pull the prop. I haven't tried anything bigger than the 29.

I'm running pump 91 in the boat and want to keep it safe. Jay told me to keep it below 1200, and that's what I've been doing. I suppose it could lean it out a little on top, but not sure how much that would really do, but eat up my safety margin. At this point, the motor is coming apart and I'll mic the bores and pistons. I hope I find something, because beyond that, I'm out of ideas. Assuming I do find something, it will be fixed and go back together with what I have (the MAD stuff would be down the road a bit, not now). My plan is to break it in for a bit, then take it to Simon Motorsports to have it dynoed.

For the boat, I bought it from AnthonySS on the S&F board, and others as well as here. This is his old boat. I was told the bottom was blueprinted early on. It is a heavy boat though, and that may have some to do with it too. I tend to run with a lot of weight in the boat. Do you think that could be 10mph worth? I'd say I carry probably 150#+ of stuff besides fuel and my body (boat bag with towles, spare plugs, prop hardware, first aid kit, fire extinguisher, paddle, gaff, 4 small bouys, throwable, laptop (for the PCU), 2-3 jackets, at least 1 spare prop - usually 2). I have thought about stripping it down to nothing and making a pass, but I haven't done it.

The gearcase is a stock, unmodified sportmaster w/1.87's.

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I would say try removing all the extra weight and see what happens. It's a FREE test to do. If you can weight everything you take out... might surprise you. One day I put my boat bag on the bathroom scale and came up with 40lbs.

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Keith,

Removing the weight and trying it is a good option. But even if the stuff was 300lbs I don't think we'll get the 10mph. Unless it was mostly in the front. Your discription gives some info that may be the culprit. The compression numbers in relation to the cc of your heads doesn't compute. On almost any stockish 2.5 the compression should be about 125-130 with 36.5cc heads. With 33cc heads it should be 140+ and with 31s it would be 150psi or so. This could be one of two things. Are you using the 1mm head gasket? It should have the .040" gasket and not the .052" one. Unless the block was decked and then we should check the squish clearance to get it close to .040". Or does this motor have exceptionally high exhaust ports? If you take a caliper from the deck to the very top edge of the port is it shorter than 1.495". This is the piston-side edge of the port, don't hook the caliper in the port. A number like 1.520" is more likely but the shorter spec is a "high" race port height. If my hunch is true, this would explain why it likes the 27 over the 29. Also would explain the compression numbers and why the motor "seems" rpm dependent. If this motor has real high porting, don't fret, we just have to go about this differently. It would explain all the senario's that you have been going through and their results. Pull a head and check this measurement. You can call me as you are doing this because thiere are a few other things to look at if the port is high. 320-267-0440 anytime. I telling you all this based on all you posts so far and the decriptions. We're getting closer to the answer. And it can't hurt to check, at least then we know.

Randy

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The gasket is the stock one listed for my motor, 27-814658 1. Not sure which thickness it is honestly. The exhaust ports are stock height for sure. We didn't touch them, and the motor was virgin when I bought it. Never been apart.

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I think I'm gonna have to tow back to Minnesota for a GPI setup.....you sold me. Ran my newly acquired RR to 113 w/2up and not set up properly. My initial goal was to see 120 but with this rig/engine. With your mods I think 125-130 is possible.

How much coin would I be looking at? Thanks.

Keith, I have SVS/PCU on my 280/260 electronics and its got a ton of snot in it.

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Thanks Dreamer. I tell ya, my next move if this motor doesn't come around this next time, is to put a powerhead on it that is KNOWN to have the balls. Then, that will tell me if it's the setup/boat or the motor.

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Keith,

We still need to dial caliper the port height and the gasket thickness. It is assumed to be right but I've been down that one before. Something is up with the compression readings and the head cc your running. Pull a head and check, won't take long and then we know. Sometimes the sleeves (the nicasil plated aluminum ones in your motor) move around a bit. This is why I want you to check it from the deck height. I've seen them move .100". Now that will mess with any motor's performance. Hate to make you do it but we really have to know for sure. No assuming they are correct.

Randy

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Randy, it's coming apart next weekend or the following week anyway, and I will measure the bores/pistons and the port heights and gasket so we know everything.

Thanks for the pointers too...I really appreciate it.

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I just added an SVS on my boat this past summer and noticed the seat of the pants difference in the acceleration and even with a heavier passenger on how easy it would still pull. I have not ran it on a clock or GPS yet but the motor reacts completely different on how it pulls into the upper rpm. I know kevin kraft just bolted one on and dropped 4 tenths off his 1/4 mile time and didn't even tune for it yet. To me that is a big difference maker. Just my 2 cents?

John

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Keith,

Are you using the 1mm head gasket? It should have the .040" gasket and not the .052" one. Unless the block was decked and then we should check the squish clearance to get it close to .040".

Randy

Hello Randy. Pulled the motor apart last night and will be measuring the pistons and holes today. I measured the thickness of the rings on the head gaskets - .044". Does that sound right?

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So we measured all the pistons and all the bores today. The pistons have little deviation as measured in 2 directions (largest deviation on any piston was .0038", most were less than .0005"). The bores were quite round as well, 3 were within .0001", one was .0004", one at .0006" and one at .0015".

Oddly enough, #2 had the largest deviation in the bore, the most out of round piston, yet it's one of the higher compression cylinders. The most square piston and cylinder (#3), has the lowest comression.

I can only guess that either that cylinder has a rod issue (short) or a stroke issue on the crank at this point.

I'm really getting fed up with this motor stuff...can't seem to build one that runs 100%.

unsure.gif

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