I have wanted to do this for a long time, so now I am diving in. I am turboing my 250cc Suzuki Ozark.


Before anyone says "Don't waste your time" or "Just get a bigger quad" or "It won't work with a single cylinder 4 stroke motor", I have my reasons and you can't change my mind.


Now, with that being said, I have already purchased the turbo I am going to use and it should be here later this week. It is a VERY tiny IHI RHF3 turbo(the same turbo found on the 660 cc Arctic Cat T660 Turbo snowmobile). It is designed to support between 22 hp to around 100 hp. It also has a ball bearing center section to help decrease lag, and be stronger to side loads(i.e. wide spacing of single cylinder 4 stroke exhaust pulses).

Now, I am planning on doing a draw through system with boost pressures eventually of 5-8 psi. I know that my current gravity fed fuel system won't support that. So, I have already aquired a vacuum operated fuel pump (I need to keep electrical loads to a minimum as my quad can only support a total of 10 amps of current draw). As long as I plumb it's vacuum source between the carb and the compressor inlet of the turbo, there should still be a strong enough vacuum pulse to operate this pump. As rpms rise, this should increase fuel flow to the carb and HOPEFULLY give enough extra fuel for low boost applications.

I know that this setup won't be very good all around, but it should work adequately for my purpose. I am not sure though if there will be a significant enough pulse to operate the fuel pump.


So, those of you that have gone to a turbo setup and are still using a carb, how do you have your fuel system done?

And does anyone have any suggestions to help lessen the long duration between exhaust pulses in the exhaust pre-turbo? I have had suggestions to build a chamber (similar to 2 stroke exhaust systems) pre turbo to help lessen the effect, and I also had an idea to make the exhaust pre-turbo out of 1 1/2" weld els, then neck it down to 1" as it enters the turbo (to help speed the flow back up).


Any help and or suggestions you guys can give me would be appreciated!!

 

there's a turbo thread in the Kawasaki section here at atv connection. maybe those guys could help.

monty

 

Hi, good luck with your turbo.Before you make it a draw through system make sure the turbo you have is sealed for that type of application or the gas will seep past the oil ring and contaminate the oil leading to aome type of failure,Engine or Turbo.a better way is to blow through the carb.It is more efficent and will allow the turbo to spool up faster.I would make the pipe out of the stock header or use stock size tubing.And you should be able to use a ele ful pump.You only need a diphram pump so the draw shouldnt be all that much.You dont have to worry about exhaust pulses hurting the turbo.You cant build a chamber (like a 2 strok) to help that.You want the exhaust to flow as fast as possable through the turbo.And it being a 250 single cylinder I would put the turbo unit within 8in of the exhaust port,but at least 4in away.Again good luck,if it works youll LOVE it!!!!!!!!!!!!

 

I just took a good long look at my Ozark to see how much room I've got in front fo the motor to put the turbo up there. There's not a lot of room, but with how small this turbo is, it would fit.

Now, I read where you said that all you did was add an electric fuel pump with one of those cheap fuel pressure regulators designed to be used with carbs. Then, with the quad off, you just increased the fuel pressure till fuel leaked past the float and you backed it down one notch. I have seen some of those small low pressure fuel pumps that only draw around 2-5 amps. Did you increase the jet size at all?

Also, did you do anything to the carb to prevent fuel and air from leaking out of it since they weren't designed to be under pressure? I'm researching online right now to see what the differances are between your stock carb vs. mine (besides size of course) to see if there is a major design differance between the two.

I would rather a blow through setup as apposed to a draw through, but it just seems like there would be too many things to worry about with a blow through (leaking carb is my primary concern).

What about a blow off valve? Are you using one? At boost pressures this low, I know it is not 100% needed as MANY stock turbocharged cars didn't come with blow off valves either. I am just curious and want to get all my questions, comments, and concerns out in the open.


Thanx!!

 

I sent you a private message about the carb leaking fuel.There is no major design defferance from your carb to mine.The Jet size is not determined by the fuel pressure.you will have to put much bigger jets into your carbs to get it to run on boost.You also need to do something about your compression ratio.bring it down to around 8 or so,the lower the better.

 

Cool, I'll check out the PM later tonight(I am about to head to my local tire shop to replace my stock front tires with 2" taller and 2" wider ones).

I am currently running a 132 jet size(my carb only has one main jet, then the needle, and the air/fuel ratio screw to adjust fueling needs). It is running too rich on the top end so I know I could probably drop down to a 130 and it would be about perfect. Now, that being said, the biggest jet my jet kit has is a 138. Hopefully that will be big enough to support an additional 5-10 hp (I doubt it). If the biggest jet and the fuel pump aren't enough, then I can always add a cold start injector to it. I would have to find a high pressure low amerage draw fuel pump (maybe one designed for a fuel injected bike???). I already have a couple of fuel pressure regulators laying around (high pressure ones).

So, all else fails I can make a fuel system using a high pressure fuel pump from a smal bike, use one of my fuel pressure regulators I have laying around, and then T off of the pressure line to a secondary carb fuel pressure regulator that would go to the stock carb. From there I can plumb the cold start injector into the high pressure side, connect the cold start injector up to one of my Hobbs pressure switches, and set the pressure switch for 1-2 psi. This would DEFINATELY give plenty of fuel for 8 psi of boost (1 cold start injector can typically support 2 psi of boost on a 4 cylinder turbo car). Of course, I'll have to tap my stock fuel tank for a return line, but that won't be difficult (knock on wood).


As far as the compression ratio, stock is 9.2:1 so it's not much higher than yours. And, I plan on only runing 100 octane unleaded race gas or higher. I know a place that sells 101 octane unleaded race gas that did INCREDIBLY well in my turbo Neon I had (it was running 32 degrees of timing advance on 16 psi of boost as apposed to 28 degrees of timing for Sonoco 100 octane unleaded race gas). Plus, since my motor is soo small, it is going to need every bit of power it can get to effectively move while not under boost.

 

Kawturbo1, I got your PM and for some reason I can't reply to it, but that makes perfect sense. Thanx for the heads up!

 

Your welcome.Let me know if I can help anymore.

 

91CavGT, how are you going to deal with the turbo oil problem? Are you going to tap into the engine system or go independent pump?
I think the suck through is the way to go. I can write a book on the pit falls of a blow through with a carb. JMHO.
For the pulse problem all you have to do is neck up the pipe right off of the head and then neck it down when you get to the turbo.

 

Well, the Ozark motor is based off of the old 250 utility Suzuki quad. That quad had an oil cooler on it. I see several spots on the motor where there are bolts plugging up what appear to be oil passages. My plan was to get a pressure gauge and tap into each port induvidualy and measure the oil pressure on each. I was then going to tap off of the port that had decent pressure, but not too high (around 10-15 psi since this is a ball bearing turbo). From there, I was going to use Kawturbo1's idea and make the return oil line dump into the oil fill tube for the motor.

Can you post up a couple of the downfalls of a blow through system?

As far as the pulse problem, is this a common method for 4 stroke single cylinder turbo setups? The more I think about it, if I go the suck through method, the more I am tenpted to just utilize the stock head pipe for about the first foot (stock, the head pipe comes out of the front of the motor, then makes a tight 180 degree turn that would be difficult to duplicate) and then increase the pipe size to 2" where it woudl go into a flex pipe, then it would neck down again as it goes into the turbo.

The pipe would be braced before and after the flex pipe so as to prevent the pipe from cracking. The turbo would also be braced.


btw, I got my vacuum operated fuel pump in the mail yesterday. It is made by Mikuni!