Webber 750 engine

WHY

Gold Member
Mark

I think your radiator concept is spot on, maybe even a "slight" scoop under the radiator , but using the shroud (tunnel) on the top feeding back to the "draft" of the prop will be excellent , this will create a real "pressure differential " and prevent any possibility or "air daming" on the front.

Tony
 
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brlcla

Newbie
Tony,

You may not be able to tell it from the picture but my boat is 7' wide. The Generac I have on the boat now is bore .80 over.... it is actually a little over 1000cc not the stock 992cc and also has a 42mm Mikuni carb not the stock. The picture shows my old 2 blade 67" prop that I swung about 4800RPM on 2:1... I now have a 3 blade I swing at 4000 on 2:1.... you have torque roll issues with any airboat just part of the experience, so yea I am aware of it but not too worried like you think I need to be.

The Walbro may not be programmable not sure... I do not have anything in my posession yet as I am still shopping around... The Weber is a good candidate for the price.... considering I can get one for near the same price as an overhauled A/C motor, but with the Weber I gain all the reliability that comes with today's high performance auto engines (EFI, EI, TC, etc.).

I would have an auto engine airboat but I wanted to keep my boat small and also wanted to try out the VTwins to personally experience what they can do. The Weber also does not weight much more then the VTwin I have... I will have to carry slightly more fuel plus have the weight of the radiator, etc. But the more than double HP rating will make up for that.

Also what I have in mind for a radiator is actually a radiator and oil cooler combined:
 

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WHY

Gold Member
Hi Michael

Sorry, I missed that the Generac had a re-drive, so the torque roll will not be so radically different. That's one sweet radiator, custom??

Tony
 

brlcla

Newbie
Sorry.... Didn't post the radiator link... Probably is custom built from Ram Engines... It is designed for Subaru A/C Conversions... Only weights 6lbs

$600 - from http://www.ramengines.com/id16.html

It is at the bottom of the page located in the far right column of pictures.
 
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WHY

Gold Member
HI Jeff

Yeah , I noticed that price when I looked it up , thats deffinately a "heavy breather" for price, but the site sure has a lot of good Suby stuff and good looking quality.

Think there may be some custom shops on radiators that will beat that price, been looking at some oil coolers for the gear box if I decide that I want to try cooling the oil in the gear box. Found some "power steering " coolers that look like they would just be perfect, one was 4 inch by 4 inch and the other 4 inch by 6 inch from "Baker specialty" in Calif. Both around $30.

Tony
 

Friendly

Platinum Member
Jeff, I think you are right, the pictures are a little miss leading the way they are posted, but the 59.95 is for the water pump above the Radiator. I did not see how they were selling that radiator for 60. but I found a source for the Rabbit radiators for 48 dollars. I ordered one because they were so cheap I could not pass it up.

With the manual that I download (thanks again for the Link Michael) I have studied the wiring and have finally got the ECU powered up, the start relay working, the EFI relay working, the Ignition relay working and lots of wires to figure out.

Tony if I By pass the three Chassis Connectors and wire directly to the ECU, I can at least reduce the length of the wires. I will still be trying to remove more of the wires but as of tonight my Weber runs.

I started it momentarily to verify I had the wiring correct. I have it sitting on a harbor freight rolling table if you know how flimsy that is. Also its 36 degrees F. here and no heat in the shop, but the more I thought about the diagrams the more I thought I knew how to get the relays to power up.

No radiator, no oil cooler, no fuel or fuel tank, no intercooler, no throttle, no exhaust, no video camera, but I had my Cell phone!!

notice the engine is not even bolted down and it does not jump.

YouTube - Weber Starts.wmv
 

WHY

Gold Member
Hey Mark

:whoo: :whoo: :whoo: WAY TO GO !!!!

Real encouraging to see that the engine does not jump a lot .

Tony
 

Friendly

Platinum Member
Yes ,
tonights low will be 29F. But I am a happy camper right now. Maybe I can get a test stand finished by Friday.
 

Friendly

Platinum Member
Good job
your on your why now.
Thanks Brent,
I feel like the Weber Team is on the way. I was not even going to mess the my Engine until after Feb. and then Tony got me fired up again. Finally, we have a source for the manual. If you have not downloaded one. Get it. It is the best 5 dollars you can spend on the Weber project. You just can't seem to get a dealer to sell you one.
The mellow rumble of the 4 stoke and that turbine wheel coasting to a stop was might nice. I did not get to post the 30 seconds or so that it ran, because I had to put the phone down to make sure it did not try to jump off the table and it was pumping oil on the floor. I could not believe how smooth it was just sitting there on nothing but the front support and the oil pan. Wow. If I can get a stand built this week, I will try to mount a prop to it to see if it will run with the prop. As cold as it is here right not, it wont need much of an oil cooler and radiator. I also have to build a small switch with two resistors to get past the ECU throttle safety switch or it will not let the engine rev up like it should.
 

brlcla

Newbie
Mark,

Where abouts you located? I am from LA too.... nvm read you profile... you are about an hour or so drive from me... I am in Lake Charles... and yes it was a cold night and a cold day at work today...

Mark are you a mechanic or just experimenting? I will need to find a good mechanic to work on the motor when I am done... I can do some but not the best to break into the inside of these motors. I have not spoken to any local Polaris guys yet but I do not expect them to offer any help if I run into issues. and from what I read the Polaris dealers in TX have dealt with the old weber that was in the 2004 msx waverunners and they dont care to even service those anymore.
 
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Friendly

Platinum Member
Hi Michael,
I worked as a small engine tech, for Sears for years and a local small engine shop. My father was a Mech and had his own Garage. He was a transmission specialist, but worked on most anything that would put beans on the table. He did not like engine work and I did most of his engine rebuilding. So I know my way around motors a little. As Birdy is a simple cow grower, I am a simple mech. I would have loved to have been a mechanical engineer, but I do not have the mind for math that it takes. As a profession, I am a parole officer with about 5 more years to retire. That is why I am so attracted to Gyros. They are mechanical marvels to me. I wish I lived next door to CB or UDI or Doug , Al Hammer and many of the other gifted people on this forum. I would be building gyros year round.
Yes we live about 90 miles apart. I am south of Alexandria, in Woodworth, the speed trap municipality. I visit Lake Charles and fly with John Churchman who lives there. He flys a 503 Dominator and has been a big support to me with Gyros.
 

Friendly

Platinum Member
Mark,

Where abouts you located? I am from LA too.... nvm read you profile... you are about an hour or so drive from me... I am in Lake Charles... and yes it was a cold night and a cold day at work today...

Mark are you a mechanic or just experimenting? I will need to find a good mechanic to work on the motor when I am done... I can do some but not the best to break into the inside of these motors. I have not spoken to any local Polaris guys yet but I do not expect them to offer any help if I run into issues. and from what I read the Polaris dealers in TX have dealt with the old weber that was in the 2004 msx waverunners and they don't care to even service those anymore.
Most Polaris dealers will not do much to the inside of a Polaris Engine. The block is Niki-sealed (spelling??) and boring the cylinders removed the lining. This can be done by special shops, but I don't know if you will be able to buy the pistons. I think a new long box with new parts from weber will be about 2700 dollars. I have talked with several Weber mechanics across the USA and the only engines that seem to have any internal problems are the jet ski engines. It seems attributed to the enclosed environment and the variety of attitudes the engine finds itself in while operating in water sports. These engines are running about 3 qts of oil. Since weight is not as critical with your application and there is plenty of structure to attach to, I would recommend that you run a separate oil cooler or one like you posted that will allow you to carry an additional qrt of oil in the cooler and place the cooler approximately mid level on the engine. The weber has two oil pumps.

The main pump receives the oil by gravity feed from the reservoir and pumps through the filter,crank, rods, cams, then turbo if equipped. and drains into the sump, (oil pan). The sump pump, pumps oil out of the engine into the cooler and back into the reservoir. The reservoir also has a vapor trap to remove the vapor and return solids (liquid oil)back into the reservoir. If you do not go with a Polaris oil tank, make sure you get something that has that feature.
I said all of that to say that if the oil cooler is located in a position where the sump pump (low pressure) does not have to labor to get the oil back to the reservoir it has a better chance of surviving in extreme applications. I also think radiators cool better close to the center of the prop where the air is pull off the radiator. I have no evidence to support that opinion.
That and 50cents will get you a cup of coffee
 

brlcla

Newbie
Mark...

I know the oiling circuit... remember I have the manual like you do.... but I knew it before I had the manual also.

And actually the higher amount of airflow is located at the tip of a propeller which is where you will get most of the cooling which is why if you see an airboat, the oil cooler and radiator are located more towards the tip of the blade. Basically the light air in front of the prop anywhere fairly adequate for cooling

I am debating on the mounting locations of the raidator, oil cooler, and intercooler. Thinking of mounting the oil cooler up high and let the sump pump push up to it and have gravity feed back down to the resevoir.... I will be using the stock Weber resevoir not the Polaris style.

If I get the combined oil cooler radiator it will need to be mounted below the engine but only 2-3ft below so the sump pump would have to push through the cooler then back uphill... I of course dont have the motor of the specs on the pump to know if pressure drop and head would be an issue mounting it like this... the resvoir would be mounted on the cage right next to the engine.... my understanding is the the oil to the main pump needs to be gravity fed.

The water cooling circuit will have the bypass side capped and I will only flow through the thermostat circuit as I will not need the bypass circuit to cool anything and I should have a large enough radiator to cool the entire flow through a single circuit.

I too have read the watercraft version being the worst. Who have you discussed this engine with as I am looking for resources also... I have spoke both with Chad @ Wasteland Performance (not the best as far as being vocal) and with Martin Filfe @ Percision Sports who has been very helpful and is a true Weber dealer who sells parts and brand new engines.
 

WHY

Gold Member
Hi Michael

Do you intend to run the Weber "stock" or try to hop it up. The reason I ask is a lot of mechanics will give you info and help if you are running a engine stock and within it's design parameters, but not many will go out on a limb if they feel you are going to try and hop it up, or maybe put it in a unusual position (like vertical in one case I know) or nitro it for dragging. Most of the experienced mechanics know the engine (even know about the bad production run of the ski engines ) and really like the engine.

I only know of one company that works with hopped up engines and they race them in jet skis, but they won't give you the time of day if they know it might fly. But since you are using in a boat that would be a different situation. They hop the hell out of them but if they get only one race and win ------no problem .

Tony
 

Friendly

Platinum Member
Higher Airflow does not necessarily mean more cooling. If it did Nascar would remove the front air dam from the vehicles but theres no point in getting into that. I know what I have found to be true with my radiator on the KB4. I am probably running one of the smallest radiator on a gyro and it has been tested in our good old hot humid climate in over 100 degree temps. I know other people with name brand gyros that have had difficulty with temps with the same engine and radiator at the tips. But Iam happy so, I am not tell you to do different. The mechanics I have talked to asked not to be mentioned as they don't work outside of their dealerships. It keeps their employer happy.
 
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WHY

Gold Member
Hey Mark

Was just looking over some of the older post and run accross your post # 382 back in Jul , it was 98 then. It just isn't fair.

Tony
 
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