Sorry, it's the red item in the pic.

 

That's a Petersen fuel pressure regulator with a boost pressure reference fitting so fuel pressure will rise and fall with boost pressure. The regulator is adjustable for anywhere from 0-15 psi fuel pressure when not under boost but with Hobbs switch activated with a jumper wire or screwdriver and a fully charged 12V battery. Typical setting is 10-12 psi fuel pressure. You should have a 0-30 psi fuel pressure gauge mounted in the hose feeding the carbs so you can see fuel pressure at all times. If the system is setup like most, the Hobbs switch will activate the electric fuel pump at around 2 psi boost. Up till then, the engine runs off the stock pulse style pumps.

I invented the world's first VMax4 turbo sled in 1991. 200 hp at 7 psi boost on pump 93 ethanol fuel. 217 at 9 psi boost.
Had it dyno tested by Dyno Tech in Batavia NY.
It's mentioned in the Dyno Tech newsletter back then.:bc2:

 

Interesting you mentioned the turbo V-Max 4.
The fastest I have ever gone on a sled thru radar, was on one of those sleds owned by a guy from Alexandria Bay in New York . I went past the gun @ 134.5 miles per hour way back in 1992, and then a friend of mine who was a bit lighter went thru @ 134.9.
Amazing those speeds could be reached way back then.
Out of curiosity, do you re-phase the crank on that sled you put the turbo on ?

 

Interesting you mentioned the turbo V-Max 4.
The fastest I have ever gone on a sled thru radar, was on one of those sleds owned by a guy from Alexandria Bay in New York . I went past the gun @ 134.5 miles per hour way back in 1992, and then a friend of mine who was a bit lighter went thru @ 134.9.
Amazing those speeds could be reached way back then.
Out of curiosity, do you re-phase the crank on that sled you put the turbo on ?

This sled was just given to me, so I am still finding out all what has been done to. I did pull the plugs and the firing order is not what was original from the manufacturer. The crank appears to have been spun 180 on this sled. I have heard both ways even installing a turbo. Patroticinnovations , I'm sure can answer this way better then me.

The VMax 4 800 turbo sled used a too small Aerocharger series 53 143/300 turbo. It was the largest Aerocharger available at that time. Maximum hp available was around 210 hp. I used a earlier larger turbo model 60, 199/250 on most of my VMax 4 turbo builds. And on all my Polaris 750/800 Storm and T-Cat 900 turbo builds. Capable of around 250 hp+. Much faster due to less backpressure. Later, a model 66 Aerocharger became available. Capable of around 350 hp on a T-Cat, 325 on a Skidoo or Storm/XCR 800.

Some guys did indeed rephase the cranks to 180 deg firing rather than the stock 90 deg. This was to eliminate the harmonics that could occur at around 9K rpm. I never did that because I always kept rpm at around a max of 8500 or less. 180 deg firing caused it to be much harder to pull over like a very large twin. Not nearly as smooth running either.

That broken hose at the fuel block would cause zero fuel pressure. It must be repaired.

The fuel block is where the stock fuel pumps normally feed into the carbs. But, when the electric fuel pump is activated at 2 psi boost pressure, the higher resultant fuel pressure (10-12 psi + 2psi boost) enters the fuel block and stops the fuel coming from the stock fuel pumps and is the sole source of fuel from that point on.

I did not develop that electric fuel system myself. It was originally developed by the lake racers (Kip Campbell and others) at Forest Lake, MN on 650 and 500 Polaris speed run racers. Up til then, I used a system of two Mercury Marine pulse pumps developed by Middlesex Performance in Massachussets. This system worked fine on a 150 hp Polaris, but wasn't workable at higher boost than 9 psi on a 650 or on the larger triples and 4 cylinder VMax 4s.:bc2:

 

Patioticinnovations

reason I was trying to find out, see pics. I pulled the turbo off to clean everything and noticed this line was cut. This is looking down between the airbox's. The line runs over to the electric fuel pu

[/ATTACH]mp.

 

frozenstiff

This sled was just given to me, so I am still finding out all what has been done to. I did pull the plugs and the firing order is not what was original from the manufacturer. The crank appears to have been spun 180 on this sled. I have heard both ways even installing a turbo. Patroticinnovations , I'm sure can answer this way better then me.

 

Great stuff. Thanks for all the info.

 

This is my first time with Turbos. The fuel line that is cut coming from the fuel block, wouldn't this be spraying fuel everywhere when it was idling? I don't see anything leaking at idle. I feel this could be part of my original post on when trying to give throttle it would just shut off. Would I be correct at thinking this way? I will replace this fuel line of course, just trying to wrap my head around everything and have it work properly when finished.

 

Patioticinnovations

is it possible to remove the exhaust pipe after the turbo and make a set of stingers to replace the silencer and pipe, using two 3/4" pipes 6 " or 8" in length?

 

That fuel block is after the stock pulse pumps. So,
yes, you should have seen zero fuel pressure. Huge fuel leaks because fuel wouldn't be going to carbs, rather it would be pumped right out of those broken hoses. Apparently you were operating on what little fuel remained in float bowls.

That sled uses two stock fuel pumps and two pickup hoses from tank.

The turbo setup connected those two pumps and the electric pump to only one of the pickup hoses. The other pickup became the return hose from the bypass regulator used with the electric pump. That regulator is a Bosch unit that returns anything over 40 psi fuel pressure back to the tank and sends the rest to the red domed regulator for delivery to carbs.

Because of how this is plumbed, you can have leakage of fuel backwards through the stock pulse pumps if the pump check valves fail to hold. This can cause internal recirculation of fuel and ultimately reduced flow capacity.

There are numerous little subtleties like this that you must understand when troubleshooting this setup.

 

That's what I didn't understand. There was no fuel leaking or running out anywhere when I started it, it just wouldn't take throttle. After thinking about this could a low charged or bad battery stopped this from happening. I mean not activating the electric fuel pump?

 

Nope. Stock pumps would be what was used until boost reached 2 psi. Does this sled happen to have a primer installed? If so, it could feed fuel briefly enough to get it running, but not fill the fuel bowls.

 

Nope, no primer. what do you think? I will be pulling the airboxes anyway for cleaning and at that time rebuild fuel pumps and clean the pickup tube screen as well. I am going to replace all fuel lines and vacuum lines as well.

 

Phil, I just wanted to Thank You for replying to topics like this. It is good for the history of the sport.
You are also beyond correct the Turbo gets small. One of my Thundercats came from Forest Lake before I moved nearby. The original owner of it also had a Turbo VMAX4, it was always fast for 800 feet with a greedy tuneup, then costed thru the beams as it 1000' in the times before they had it more figured out.
The Thundercat was the slower of the Two but Never Went Down. The Forest Lake area is stil a hotbed of Snowmobile Performance. It would be nice to see some of these older Performance Builds on the Ice Again. Machines like this should be remembered fondly and kept running strong. It's fun to see.

For Everyone Reading and Learning, but maybe not posting to say it THANKS!

 

You're more than welcome Joe. These older performance sleds were a blast. The sound of a unmuffled V-Max 4 turbo sled is spine tingling. Sounds like a V-12 Lambo.

Vintage sleds are becoming very popular these days.:bc:

 

First of all, I would like to Thank You PatrionicInnovations very much for taking time to help me sort this sled out. You have gone above and beyond with your knowledge and experience and I appreciate tremendously. Just like paying it forward. Is there anywhere that you know of that would have rebuild kits for the Taiyogiken fuel pumps? Yamaha Parts Warehouse has the fuel pumps but no rebuilds and they want 93.00 for each. I've searched around and couldn't find anything. There is a lot of sleds out there that use this pump, don't understand why no rebuild kits.

 

Nope. Those pumps also had the OEM oil injection system connected to them. This helped to lube the carb slides but was criticized because it took too long before the richer oil supply at WOT reached the crankcase. Most turbo kit installers plugged them at the pumps with rubber caps and clamps and routed the oil injection hoses directly into the exit mouth area of each carb. Bender sold a conversion kit.

In your case, I'd use one or two of the typical Mikuni pumps along with the oil injection kit. You won't need a lot of pressure or volume because the electric fuel pump will do all the work under boost.

You need to be aware that this turbo is a very fragile item and uses ball bearings wick fed with special synthetic oil from a internal reservoir. The variable vanes inside the exhaust housing make it unnecessary to have a normal wastegate. They act as the wastegate and have a much quicker boost spoolup time because they are adjustable to optimize this characteristic.

One more thing. Many of those Aerocharger turbos are internally damaged from piston or other debris going through them at sometime or another. To inspect the turbo for exhaust vane or turbine wheel damage, you must loosen the band clamp completely in order to get a screwdriver under the center vane pack assembly and pry it up out of the exhaust housing. DO NOT pry upward on the upper aluminum compressor housing. This will dislodge the tiny spring loaded ball bearings. First mark precisely where all three pieces are aligned. (Compressor housing, Vane pack, turbine housing).

If you see anything bent or broken, you are in for a $750+ repair bill from Aerocharger/Hyperturbo.
There used to be a guy named Turbo Doc in Utah who repaired them.

 

When looking to find rebuild kits I stumbled on some info regarding the pumps. They mention there is an auto shutoff valve inside them. Could this be happening in this case to me not seeing any fuel coming out of that broken line at the fuel block?

 

Yes, they do have a shutoff. Vacuum operated when you crank the engine. Supposed to eliminate the need for a manual shutoff. Doubt that this is the reason if engine is running unless the vacuum isn't getting to the pump. You may find that the previous owner has installed a manual shutoff or some other check valves somewhere. The engine can't normally run very long, or even start, if fuel isn't being pumped from somewhere.

 

The old muscle sleds are cool. A turbo just makes them that much cooler! I was just a little felluh but I seem to recall a turbo vmax coming to the radar runs in Medway hosted by the East Branch Sno Rovers. I want to say it was Trask performance from waterville/Winslow Maine, but I could be wrong. No matter who owned it, I remember it running mid 130s in 1000'.

 

Here is my lake racer 92 turbo VMax 4 before the throttles stuck wideopen and I destroyed it by hitting my neighbor's garage. That turbo is the much more powerful 199/250 unit. Broke six ribs and ended up in the hospital for 3 days.

 

My 94 750 turboed and 95 800 non turbo Vmax4s.

The 94 had a handtooled leather seat.

The 95 has since been turboed.

 

Very nice sleds. Here is on of mine back in the day late 70's early 80's. 650 hirth arctic cat, 340 txl indy,also had 440 Thunder jet and a '79 Tx 440 for grass and snow drags.

 

I checked through the fuel system. Found no shutoff or check valves. Attached hand drawing on what I have and found. Borken line coming from tank then tees to the electric fuel pump assembly, the same line continues and feeds one pump which feeds fuel block. coming from the electric pump line going to fuel block is broke as well. The other line coming out of the tank feeds the other pump which feeds the fuel block. Both vacuum lines from both pumps are connected to the crankcase. The only way to maybe get fuel in this state is from the one pump where the line is not broken. My thoughts, how about yours?

 

You seem to be missing the return hose from the Bosch regulator/bypass back to the tank via the second stock fuel tank pickup hose. I believe that both stock pumps, and the electric pump, are connected to the single pickup hose.

Also, if the hose at the 4 hose distribution block is broken, none of the pumps can push fuel to the carbs. And there would be a massive fuel leak.

 

sorry didn't send first time.

 

new drawing attached. Missed the bypass, sorry. There is no return line going back to the tank. both pickup tubes, one supplying elec fuel pump, bypass, and vacuum fuel pump. The other pickup line runs directly to the second fuel pump.

 

Where should the return to the tank come from?

 

Should both vacuum fuel pumps and the electric pump be tied into one pick up line coming from the tank, then the second pick up line from the tank go to the bypass line?

 

Yes. Your red line in the sketch is wrong.

You could also run a separate bypass line back to the top of the tank and leave the current setup as is.

 

Patrionic,
Does this look correct to you? The only thing I can find for the bypass, that will go back to the tank when I replace with new lines.