TOPIC: Spilling the beans on my supermodified 1500

OK guys here it goes,first a little background. This started out as a tongue in cheek joke over on the Merc news group. It has evolved into a real engine that is snarly. While cleaning out my garage 3 years ago I tripped over the leaf blower, while cursing, my mercaholic brain suddenly did the math for the cfm output of the blower and imagined it blowing through an inline six. The rest is history, I was hooked, the blower was shelved until I could come up with an injection system, then while browsing KIJIJI one day I came across a set of 3 throttle bodies for a Polaris snowmobile. Wrong spacing wrong length, 3 cyl instead of 6, 48MM throat.....Perfect!

More to come.

Teaser, now I am intrigued!

Bob

Ok, heres some more. Now I had an injection system capable of feeding a 3 cyl 120 hp 2 stroke with probably a little margin extra. However, the snowmobile runs tuned pipes to push that extra fuel back into the cyl. I do not have that bonus. Plus the design criteria for the injectors limit the duty cycle to 80%. Fuel pressure is regulated at 38 psi. Sooo...I have to fatten the fuel map, and I have to feed twice as many cyl. Solution so far has been to fool the Polaris EFI computer into thinking it is running twice as fast as it is. So at 2000 rpm of the merc the polaris is feeding fuel for 4000 rpm. Now each injector squirts fuel twice per revolution. I triggered the EFI computer from one of the switch boxes at TDC.
Yes, I converted the 1500 to ADI ignition as well. At the same time I changed to a 16 amp stator and a V6 flywheel with an inline 6 ring gear swapped in.

This being the case, every time one piston is at tdc the adjacent one is just ready to embark on its compression stoke and draw fuel behind it. Each pair receives a squirt at exactly BDC for the piston in question.

The snowmobile engine made 40 hp per cyl, the merc makes 25 per cyl. I have my 80% duty cycle back, I am golden unless I top out the fuel map at 12000 RPM. More on that later.

Ok, lets move away from the injection system for a moment and talk about the nuts and bolts of the 1500. The block I used was a well seasoned 1974 block that had puked number 3. The crank and pistons were available too so I was able to analyze the damage. Fresh water block from Illinois (chicago). I made a road trip to get the block, 1200 KM round trip, plus a hotel and shopping for the better half. I affectionately call the block my Chicago block. I junked the pistons and the crank that were in it and hand selected a new crank from my stash, polished the crank and inspected the surface for voids, chips, etc.
Next, from my collection of rods I picked 6 of the best, checked for true and then polished the big end and small end. Same inspection process as the crank, using a lighted 100x magnifier.
The rods were then weighed and documented on an Ohaus digital laboratory scale down to 4 decimal places in grams. The lightest rod was 299 grams and became the target for the others. The rods were then weighed end to end, compared, and determined where the weight had to come from in order for each big end to weigh the same as well as each small end and total out at 299g. Material was removed from each rod as required and the rod was stress relieved.

Pistons, I scored 6 new persan high dome pistons with rings (3). Each piston was weighed on the same scale and adjusted accordingly. Then each piston was paired with the best rod assembly based on weight. Final variation of all 6 complete assemblies was less than .1g.

The pistons were .030 over so next came boring the block. I started making a specialty boring machine for the inline. Figured it would come in handy down the road.
During this process I made friends with a local machine shop owner who was interested in what I was doing. He said " i'm not using my old milling machine (a 1960,s bridgeport mill with a j head 5" of travel) why don,t you just use that!''

I was in heaven. The quill was a little sticky on the mill head so I overhauled the head for him before I started. I also zeroed the machine, and leveled it. I wanted the bores true. I set up a heavy duty boring bar on an extension that would allow the head to travel all the way into the cyl. After a day of setting up the machine I took a thin cut off the number 3 cyl, the one that had failed. It took .005 to true the cyl. I then progressively made 6 more passes, finishing with a .001 cut to the final dimension of 2.905 inches. Repeated this process 5 times. No computer controlls, no plc, just good old fashioned machining. I had a ball.
While I had the block on the mill I took the top of the non adi block down to the size of the ADI front cover.
Ultimately I used a ball hone to polish up the machined bores and knock down the sharp bits left by any machining process. Finished honing in the reverse direction to create a plateau honed surface. Final bore gauge measurements showed the bore to be true, exactly 2.905 dia, no tapers.

OK, the intake system. Thanks to the experience of Jeff G, a seasoned inline 6 racer, I learned how to modify the reed blocks to allow more air flow. ultimately the reeds are the limiting factor on the inline 6. Following Jeffs direction I removed the centre web from the reed block and smoothed inside of the reed block to allow non turbulent flow around the core of the reed block. I blended the backside of the reed holes to direct flow out through the reed openings. Final step was lapping the block surface and installing banjo reeds. For those not familiar, the banjo reeds have a narrow neck just like a banjo neck. The stock reeds are more of a tear drop shape with a thicker mid section. The banjo reeds allow the reeds to open quicker and stay open longer. Kinda like increasing the duration on a 4 stroke cam. The reed stops on a banjo set up are smooth without the "kink" where the regular ones are bent. Open quick, stay open, slam shut, the perfect intake valve.

The throttle bodies are much larger in diameter than the carbs so the intake cover was modified to align with the throttle bodies. A 1/2 inch aluminum plate was cut to accept the throttle bodies. The carb mounting studs were removed and the holes filled and then new holes drilled and threaded to accept the larger diameter throttle body. The opening in the front case was opened further and a swirl was machined in the throat causing the fuel air mixture to spiral. All in all the plenum volume behind the butterfly s and in front of the reeds was increased approximately 30% with volume coming from both diameter and plenum length to maintain mixture speed and accelerate it as it progressed down the plenum. The injector stream is aligned with the back of the reed opening.
The objectives were simple, open wide, fill with fuel and air.
All casting lines were removed from the castings, sharp edges can cause the fuel to drop out of suspension.

Ok, back to the efi computer. It runs open loop, no o2 sensor. The fuel map is shifted based on the crankcase temperature, intake air temp, rpm, and throttle position with a standard TPS. The atmospheric pressure is also monitored to adjust for altitude etc. If the crankcase temp goes over limit the system defaults to full rich and blows fuel to cool it down. Useful for an inline. I decided to mount the crankcase temp sender right on number 3. Hmm, wonder why?? Idle circuit is offset separately under 2000 rpm controlled by a 100K pot. Think of it as a separate idle screw. This is an area that I am currently modifying, the problem comes from the fact that the merc idle is largely controlled by timing advance, before the butterfly opens. As a result rpm is increasing but the tps is not advancing. I will likely remove the gap between the advance and throttle opening. Right now the lowest idle I can achieve is 1200 rpm, goal is 500 rpm. More on that later too.
All the fuel mapping is stored on an eprom which I will be replacing with an EEprom and interface that will allow me to tweak the map on the fly and bump the map up or down for specific RPM and load. The tuning software runs on my laptop and was developed by a gentleman from Finland named Rensu, a polaris snowmobile enthusiast.

More tocome, feel free to ask "how did I" or why questions.

To quote a famous Chicago resident, "Holy Cow!" I think everybody is in shock Dave, I know my eyes are bugging and my jaw is on the floor. Awesome rendition of genius sir, please keep us posted on your progress and enlighten us on your techniques.

More to come, feel free to ask "how did I" or why questions.

Any idea/estimates on what the final HP output will be?

You lost me at leaf blower!!!! LOL

Leaf blower=Turbo charged.EFI via Polaris.Blue printed and balanced into micro grams.Ported, polished, mapped and ready for the "Need for Speed" So what hull are you planning on putting this bad ass on?

OK, now I'm drooling to know the rest! I second Mark's question, what is the final predicted HP?

Bob

Thanks Mark, I don't like to make wild predictions of horsepower, mathematically the beast should be happy running at 6200 rpm hp should be in the 175 range at the power head, 150 at the prop. Time will tell. This is a new block so I won,t do any power pulls until it is well broken in. I would like to say I have it on a really cool fibreglassic...its on my 18 foot aluminum bass boat, Lowe 180 WZ.
here is a pic looking down its thoat....say AH!

I have to resize the image, hang on.

dont want to be the wet blanket but you cant pressurize a two stroke with a turbo or a supercharger. there are no valves to stop everything blowing through the motor . someone tried it over at scream and fly (never worked ) and the work was top notch . if it was viable to do so the manufactures would have done it many years ago .

Thats OK Gil, I have no intention of supercharging, that reference was to the tongue in cheek leaf blower incident.

Sorry for the crappy pic but you get the idea.

gil_72gt-160 wrote:

dont want to be the wet blanket but you cant pressurize a two stroke with a turbo or a supercharger. there are no valves to stop everything blowing through the motor . someone tried it over at scream and fly (never worked ) and the work was top notch . if it was viable to do so the manufactures would have done it many years ago .

By the way, it can be done, anything can be done. The reason the manufactures dont do it is cost and reliability.

Daveswaves wrote:

gil_72gt-160 wrote:

dont want to be the wet blanket but you cant pressurize a two stroke with a turbo or a supercharger. there are no valves to stop everything blowing through the motor . someone tried it over at scream and fly (never worked ) and the work was top notch . if it was viable to do so the manufactures would have done it many years ago .

By the way, it can be done, anything can be done. The reason the manufactures dont do it is cost and reliability.

it cant be done , because of the port positions . the exhaust port open first expelling the spent gases then the intake opens taking the new charge while the exhaust is still open . no way to trap a pressurized charge . sorry bud ya cant do it .

turbocharging and supercharging have been and will always be a viable /reliable cost effective means to increase horsepower on four stroke gas and diesel engines , just not on two strokes because of the reasons i stated in my last post . mounting a turbo on a two stroke poses a real problem , lubrication ? that would require a totally separate lubrication system and a supercharger could be mounted but would basically just blow fuel through the engine with out increasing combustion pressure .

Lets talk about the exhaust area. The port heights on the 1500 are already optimal. You could raise them a tad but unless you are in a straight line drag race you will be sorry. The trick with the exhaust is to smooth the exit, remove casting lines, flatten the floor, aim for a D shape. There is fuel in that exhaust and if you keep it in suspension some of it will be re injected by the exhaust pulse. Yes if I could I would run stacks, but I do have to get out of the marina and through the no wake zone. Oh yeah, I also live here. LOL>

Gil you are certainly entitled to your view, it is a commonly held one until you see a 2 stroke snowmobile at the grass drags with a turbo. Slower off the line yes, winner at the end, yes. The reason is all about fluid dynamics. Remember, air is a fluid, just a compressible one. Here is a pic of a turbo merc 40 Hp as an example.

There are several turbo charged motors that have been made and shown on Scream and Fly website.

I think I have seen an old inline 6 turbocharged a long time ago.

Its very possible, but is time consuming and not easy to do. I dont even know how they do it? I just know its been done.

I need to re-read some of those old posts and see the outcome of each motor.

Conrad

Here are a few that I found quick.
Conrad

A v-6
Conrad

And one more.

I edited what I said earlier, I dont think it made sense .

I do think the exhaust has to be tuned to hold the extra intake charge in when running lot of boost.


I have no personal experience with this, just my thought after seeing others work

Conrad

And,...We're kinda drifting away from the discussion related to Dave's EFI Stack-6 project, which doesn't include a turbo or supercharger.
Dave,
In discussion with some old T2x & 1500xs boat racers it sounds like the xs can run a constant 6800 at 27 with 100LL 40:1 and the T2X can maintain a constant 76-7800 at 27 so your plan to run max RPMs of 6200 are very conservative and likely can be boosted up a bit once everything in your program is proven.
By 'constant' I'm referring to their use in Marathons, etc.
In both cases either an A25 switchbox is required or as you're doing - the unrestricted ADI.
Thom

a interesting read .

www.screamandfly.com/showthread.php?208365-Merc-Super-Charger

Thanks Thom, the rpm limit at 6200 is just a practical one for me. Mainly due to the current EFI computer, the polaris. Since I am running it at 2x speed thats 12400 rpm in the polaris box and there is a revlimit at 13000. Actually there is no fuel map beyond 13000. As you know, from past conversations, I am working with a guy in New York State who developed a modification for the polaris computer and that mod will be going into mine when its ready. Then I can re write the fuel map and extend it. Till then I am 6200 WOT.

At the moment my challenge is at the lower end, idle is too high. I am going to rework the throttle assembly and timing advance to take care of that, I have fattened up the low end with the tuning pot. I will shorten the gap between throttle open and timing all in. No link and sync on this puppy, in fact, all of the landmarks are gone. I do not even have a timing pointer installed yet although I will. I have a different digital camera, I will try and get some decent shots of the set up and post them.

Yes it is an interesting read and Go Fly has a unique product idea.
My comment is the very last post. Patents take time.

Another read on the turbo issue. boatracingfacts.com/forums/showthread.php?t=3761

6200 is not a bad place to be. Your near the peak HP range for the xs block. My xs block "feels" like its peaked right around 6000, but pulls up to 6500 well. I have run 6900 with it in some drag situations, but felt it was faster with a taller prop keeping the rpms at or under 6500.

Im running 100LL 40-1 and only 23 deg right now.
Conrad

Thanks for the input Conrad, I know what you mean about the sweet spot, my current inline settles in at 4900 on pump gas 21 deg timing with a 20P Lazer11. Im happy with the 6200 for now, its a new block with lots of mods.

What inline is running 4900? Dont lug it too much....


Thom is right that it is conservative @ 6200. When peak HP is 6000 you have a window of great HP in the 5500-6500RPM So you might be bumping on the RPM limiter quite a bit. So prop choice will be parmount.


Post some pictures when you get time. Id love to see it.

This winter I am putting together a 1400 power port block. High dome pistons, slight exhaust port work and have it ready to go head to head with my XS motor. I think I can get it to run pretty good squaring the ports out on the exhaust side.

Conrad
Conrad

milkdud wrote:

What inline is running 4900? Dont lug it too much....



Conrad
Conrad

Yeah I know and I honestly do not know why this one is happy there, it just is. I have run this one in bass tournaments for 3 years, the piston tops are like new, you can still see the casting marks on the dome looking through the plug hole. It is a mid 80,s non powerported 90 HP adi block, running high domes, with a 75 front cover and distributor ignition. I put it together 3 years ago, we live in a marina so it gets frequent use and up until last year was in the boathouse ready to go at any time. Last year I trailer-ed it, The block is pulled right now and it will be going on a stock mid and lower to push a pontoon, a respectable retirement.
I will take pics tomorrow and post them, I was busy fishing todaay

Dave wrote:

I will take pics tomorrow and post them, I was busy fishing todaay /quote]

Good for you Dave. I spent the day on the boat yesterday. Can't wait to see your pics!

Bob

A little busy, the pic that is, here you can see where the computer is tucked, the side of the throttle bodies and the air temp sender.

Here you can see the fuel pump and the fuel rail and injectors.

Here you can see the ballast resistors for the injectors, low impedance.

Wow, now that's a set up. How do you make heads or tails with all that wiring? Well guess it's easier when you do it yourself. LOL Great set up Dave!

Bob

Thanks Bob. I still have to shorten some of the harness but it does all fit under the cowl. I took the pics while setting the W
OT timing (you can see the connections for the light). I know the wiring by heart