Carbed 2 stroke turbo guy's !!!

[Quadzillaracer]

Well I'm sorry for throwing my .02 in there Gus, don't want to get in a pissing match, seems there is enough of that on the sled forums these days. Just a different way to skin a cat that's different than your way and has worked flawless and has real results to prove it. I'll just respectively bow out of your thread now. Thanks.

 

[DWHalverson]

We have used the Hobbs switch and prefer NOT to use them. What we found was the switch delivered the fuel fast and at a higher pressure and rate than what was needed for the boost as it came up. It never caused any problems and has been used for many years. We just prefer not to use them. When designing the XP turbo kit I wanted less parts to fail and eliminated the Hobbs switch and relay. The fuel delivery with only an electric pump seems to be more linear in it's delivery of fuel. As the boost comes up, the fuel pressure comes up with it. Instead of just WHAM!! 15 pounds of fuel and the boost is coming up. The switch and relay can fail and I didn't like that so now we just run the electric fuel pump with no stock mechanical pulse pump. It starts first pull most times and the fuel pressure is always at where we set the idle pressure.

Dave Halverson
R&D Custom Turbo Werx

 

[gus bohne]

Well I'm sorry for throwing my .02 in there Gus, don't want to get in a pissing match, seems there is enough of that on the sled forums these days. Just a different way to skin a cat that's different than your way and has worked flawless and has real results to prove it. I'll just respectively bow out of your thread now. Thanks.

thank you for stepping out ,, what you and yours are using has been done and was used for the RXL in 1990 .
It worked OK for on off trail use but at best it was OK..for ease of use I installed n20 fogger nozzles as the power jet orrafice. it allowed easy curve adjustments but always was a rich gugrgle when riding in the low boost / transition zone due to fuel pump on /off fluctuations.

There really is a neater simpler way to have volume on demand..
Nice to see someone else has gotten the v max up over 148 mph @ 1000 feet.
we went that speed in 1995 with our own 750 using an old 325 vane aero.
they are heavy but easy to make power with...


Gus

 

[Fack]

There have been several setups that run a hobbs switch and relay to turn the pump on and off with boost. I have ridden a couple sleds with this very setup and they seemed to work well. The problems are as previously stated. The higher fuel pressure that comes with running this type of system causes a higher potential for flame outs and bogging when going in and out of boost. It also gets worse as you go through the bumps and jumps. The biggest problem I have seen is the relay failing and not turning on the pump when boost pressure comes on. In a matter of seconds the motor and turbo were wiped out. Expensive fix for a cheap relay. There are several who claim they've never had a problem in X amount of sleds, but it just doesn't seem worth it, especially when the other alternatives work so well. I'm glad to see that the subject was brought up. Understanding the different methods gives people more insight on the inner workings of these carbed turbos.

-Fack

 

[DWHalverson]

Been hiding out again? Glad to hear you chime in. My explanation was rough and I felt what I was trying to say, was said better by yourself and others.

Dave

There have been several setups that run a hobbs switch and relay to turn the pump on and off with boost. I have ridden a couple sleds with this very setup and they seemed to work well. The problems are as previously stated. The higher fuel pressure that comes with running this type of system causes a higher potential for flame outs and bogging when going in and out of boost. It also gets worse as you go through the bumps and jumps. The biggest problem I have seen is the relay failing and not turning on the pump when boost pressure comes on. In a matter of seconds the motor and turbo were wiped out. Expensive fix for a cheap relay. There are several who claim they've never had a problem in X amount of sleds, but it just doesn't seem worth it, especially when the other alternatives work so well. I'm glad to see that the subject was brought up. Understanding the different methods gives people more insight on the inner workings of these carbed turbos.

-Fack

 

[oldschool]

Dynamically Venting the sides to a pitot is JUST one way to do it..

In the case of the oem flatslide like yours you could go that route or a bov from powderlites,, very nice unit.
The only issue with a BOV is venting it away from clutchs and soforthe.

bowls will always be vented to airbox for a static signal.

oil pressure for a ball unit will be very very low, Twister has a nice small unit .
Shane uses the oem injector pump to supply oil on his sleds..

ball units just need oil present NOT under high pressures as a plain bearing would need..

Gus

Gus, do you run the same size hose for all this venting? Seems that the 1/8" hose found on most carb vents might not be big enough to equalize/relieve the pressure on the slides. Also do you vent at the top of the slides or at the back of the slides toward the top?

I like the idea that a stock oil injection pump can be used to oil the turbo. Does that mean that the oil tank needs to be higher than the pump like factory injection tanks?

Thanks for all the great info. Very interesting thread.

 

[zrt1]

Gus, do you run the same size hose for all this venting? Seems that the 1/8" hose found on most carb vents might not be big enough to equalize/relieve the pressure on the slides. Also do you vent at the top of the slides or at the back of the slides toward the top?

I like the idea that a stock oil injection pump can be used to oil the turbo. Does that mean that the oil tank needs to be higher than the pump like factory injection tanks?

Thanks for all the great info. Very interesting thread.

I would also like to know about the venT lines. also when running the BOV do you tap just one carb or both and tee them to the BOV?

 

[gus bohne]

Yes I use all the same id lines.

I have never used a bov, but will on the rt laker with a turbowerx set up.

I vent the carbs slides{ when it allows } thru the slides themselves.
I drill thru adjacent to the needle hole in the slide.


gus

 

[zrt1]

Gus where is the best place to pull boost off of for the wastegate actuator? Is the air box to far away or should it be on the compressor housing? all so my carbs slides are pressurized via the top of the slide cap any probs. with that? I am running the CPI mech. oil pump what should the bypass valve in the oil tank be set at (psi) approx? thanks.

 

[Tonysnoo]

Hi Gus,

Thanks for all your knowledge and help. I started my project a few weeks back. The pipe layout and turbo worked out quickly.

Building the airbox has taken tons of hours. It would have been easier, but I thought I would build it with o-ring seals on the carbs. I think I got your formula right. I made it two bore sizes deep and just the bell size high with just enough width to cover both carbs with a little overlap for volume.

The way the pipe and turbo layed out I was able to run as short a charge tube as I could figure. I plan to take the bypass valve back into the air intake. I figured I would set it up with two intake systems. With the hood on, I'll intake up by the gauge and light openings. With the hood off, I'll run the air cleaner.

Next I have to fab up an oil tank. I'm sure it will go a lot faster than the air box. I'm going to use the oil injection pump for the oiling. I have been running this premix for a few years anyway. I am going to use the stock fuel pump with a mallory regulator. I have a ton of room to fab up a nice silencer. I figured something with a 3" core to keep the back pressure at a minimum.

Wish me luck and please any suggestions anyone has.

 

[triple7]

Is this the Cutler 1000 M chassis turbo setup?? Looks pretty slick man!! That thing should rock!!

Jake

 

[gus bohne]

Tony, what is the stock fuel pump rated at in lph?
for safety sake you might want to go with a better pump rated for 500hp minimum.

All the rest looks very nice, I like the silicone bov adapter, clean.

Gus

 

[Tonysnoo]

Is this the Cutler 1000 M chassis turbo setup?? Looks pretty slick man!! That thing should rock!!

Jake

Yeah it's the M7/Cutler1000 big bore. I was worried about port timing, but have been given some reasurrances by a few folks that it shouldn't be too big a factor. Took off the twins, going to retard the timing and lose a little squish. I plan on running between 7-10 psi boost. We'll see how it works out. The single is from D&D and looks(on dynotech) to have a nice wide powerband with no abrupt drop off after peak power....we'll see?

It's all a crap shoot right now, but I have been getting a lot of tutoring from Gus and a lot of the rest of the folks who play on this forum.

Thanks for the compliments...........getting anxious to hear it run.

Hey Gus, I can run the pump with the regulator in the system to measure flow. I'll restrict it enough to maintain pressure. How much flow should I be looking for?

 

[devilrmk]

Any recomendations for an oil pump to feed a non ball bearing turbo?


Also what do you guys use to check pipe pressure, to make sure there isn't too much backpressure?


Guess these aren't specific to Carbed turbos but that is what I am building.

 

[triple7]

Your backpressure is pretty much totally set by the turbo. Pressure will increase as you run more boost.

Jake

 

[devilrmk]

Your backpressure is pretty much totally set by the turbo. Pressure will increase as you run more boost.

Jake

I am more worried about if my turbo is big enough. Going to do a little experimentation with smaller turbo's trying to get a more responsive turbo that will not be pushed more than about 10lbs. I don't want to get excessive backpressure and burn down.

 

[gus bohne]

On the carb sleds I set up, I tap into the center section of the pipe and use the pipe signal to control fuel pressure rising rate.

1. it comes up faster than boost .
2. it should be 4-5 psi higher than boost to use the pipe correctly.
3. it allows lower standing fuel pressure and higher operating fuel pressure .
4. It allows you visual of pipe back pressure at any given boost level.

the pipe being 4 -5 higher at all times gives you that ,,plus boost to raise the fuel pressure.
example, 4 psi fuel, 10 psi boost = 14 psi feul under boost.
my system = 20 psi under boost at the same base of 4 to start..as pipe should be 14 + at 10 psi boost. so signal to regulator is 14 + rather than just the intake sides 10.

On carb sleds this also causes a rich condition when you bleed more boost as the fuel pressure will continue to climb and cause and inrichment condition that will save you from a lean out..

We typically will turn down the powerjet when jumping from 10 -18 psi rather than open it from lack of fuel volume..

Gus

 

[happylilcuss]

Ok so I have a new question and this seems to be the thread to ask it. I have a highmark rec T600 carb. When reggie built the kit he used the stock oil injection pump to oil the turbo.
I want to add a tank like the bd kits have and oil the turbo through a closed system. I am tired of oil leaking everywhere under my hood. What is it going to take to do this?
I can see I am going to need a tank. I am going to need to plum it into the turbo. Will I need a pump? I have a 12 battery I am using to power my af guage so I can tap into that.

Well, any help to steer me in the right direction would be grealty appreciated.
Dusty

 

[genesmob]

Did everyone hear what quadzillaracer made with his v max 4 at dynotech last week? 507hp, 300 plus ft/lbs of torque with over 300 lbs/hr of fuel. Thats one hell of a carbed two stroke turbo!! Especially for under 1000ccs.

 

[studsrsx]

Lets keep this thread at the top. I like the info on the hobbs switches.