Turbochargers?

[spookum]

I bet it is taking a toll on his account too if it says "no reasnoble offer refused" LOL merry chrtistmas!

[smog]

I would stay away from the GT15. it's a way too large turbocharger for your project.

something closer to what you need would be the IHI RHB31

IHI RHB31 Turbo Charger - Vespa Labs

it's what I was planning to add to my 19hp kubota B7200 tractor. It's a lot easier to add it to the diesel engine but could be done on your engine. I would consider putting it between the carb and the intake for a draw through setup.

[Groundhog]

Quote:
truckinwagen
you need to be very careful with forced induction, it is really easy to lean out and blow up the motor under boost.

if you are running a blow through(carb after turbo) you need to be sure the turbo is set up for being pressurized.
if you are running a draw through(carb before turbo) you need to be sure the turbo has the right kind of seals in it(I think carbon seals are what you want, but don't quote me on that)

Groundhog says: Yes carbon seals are required. The carbon seals add friction, and are hard to find in a small turbo. A draw thru cannot be intercooled.
Fuel injection, blow thru, intercooled with closed loop computer control is the way to go.

you also need to set up a rising rate fuel pressure system, so the carb will deliver more fuel as boost rises, which means a new higher pressure fuel pump, and a fuel pressure regulator.

Groundhog says: You speak the truth, and have some good turbo knowledge man!

there is lots of power to be had with forced induction, but you need to be careful not to destroy your motor(and it happens fast, just a minute with a bad tune will toast a motor)

Quote:
-Owen
if you want inexpensive boost/EGT gauges look at Auber Instruments.
they are digital, can be set up for a wide array of sending units, and you can get them with an analog output for data logging purposes.

they dont sell an O2 sensor that I know of, but there are lots of good choices for wideband O2.

the real way to figure out how well a turbo will do on a motor is to get ahold of the compressor map, and plot some points based on your motor(usually in LBS of air per hour, and differential pressure ratio)
if your motor falls into the high efficiency range of the compressor map, you have a good match

I like to look at a few RPM points, where you want to start seeing boost, where you would like to run the motor most of the time, and the highest you will ever rev the motor to.

a poorly sized turbo can behave very poorly, even destroy itself.
smog
I would stay away from the GT15. it's a way too large turbocharger for your project.

something closer to what you need would be the IHI RHB31

IHI RHB31 Turbo Charger - Vespa Labs

it's what I was planning to add to my 19hp kubota B7200 tractor. It's a lot easier to add it to the diesel engine but could be done on your engine. I would consider putting it between the carb and the intake for a draw through setup.

Groundhog says: Good points, The compressor map is the most important thing. Yes , the gt15 is far too big. You will barely start waking it up with a 600cc engine at full flow, perhaps 3 psi boost. Yes the IHI turbo is the best option for our engine size. Also a big “yes” on wideband O2 readings to figure out how your fuel mixture is doing. You could easily double the power of our engines with a turbo, just cant get lean at boost or you will be gathering pieces!

[Stonewall]

OK, I think we need to slow down a bit, one thing at a time so that I can understand what we're dealing with here.

Let's pick a turbo first.

I have a carbeurated, 624cc (.624 L) 2-cylinder gasoline engine. <--------- This is what I want to turbocharge, an "ideal engine" (fuel injection, etc...) is not in the budget.

I will sink no more than $750 initial investment into this. If it works, then more is possible.


The GT15 is designed for a 1.00 L to 1.60 L engine. That's about .4 L too large. Please explain why this is too large, as it's less than the difference between the maximum and minimum displacments that this turbo is intended for.

The GT12 would probably be best, but I haven't ran across an affordable copy.

On the IHI turbo, are you saying i'll still be gaining power trying to squeeze the exhaust that normally flows through two 1 1/4" pipes into an inlet the size of a quarter?!?!?!?!?

I'm just trying to get a basic understanding of what I've started here, as I'm only a high school graduate with a few college hours under my belt.

Thanks!

[smog]

I will sink no more than $750 initial investment into this. If it works, then more is possible.


The GT15 is designed for a 1.00 L to 1.60 L engine. That's about .4 L too large. Please explain why this is too large, as it's less than the difference between the maximum and minimum displacements that this turbo is intended for.

...so it is just about 60% too large for your engine. And I would consider a 3600rpm limited 624cc as a regular 6000rpm 400cc. So I would be hunting for a turbo made for a 400cc engine.

The UTV guys are using a GT1544 on the high rpm, high power 900 - 1100cc RZR. but the ideal engine for this turbo is a 1300cc engine. using it on a 1000cc will make it lag at low rpm.

and I would still go for the drawn through setup without intercooler. it's simple, it work and the carbon seals are just required for extra longevity.

but at 750$, I'm still on the 4stroke sled engine

[Groundhog]

Quote:
I will sink no more than $750 initial investment into this. If it works, then more is possible.

GH: I understand the budget constraints... You could try blowing thru a Mikuni for some basic fun. It is still important to raise fuel pressure with boost somehow. Keep the boost low and the mixture rich, and you should be ok.

Quote:
The GT15 is designed for a 1.00 L to 1.60 L engine. That's about .4 L too large. Please explain why this is too large, as it's less than the difference between the maximum and minimum displacments that this turbo is intended for.

GH: It always seems practical to try a larger turbo, but a <800cc engine doesent move enough air to get the turbo spinning. It would try to start working right at the very upper limits of the engine, and only while climbing a steep hill on top of that. I just wouldnt want to see you spend money and time on this unsolvable situation.

Quote:
On the IHI turbo, are you saying i'll still be gaining power trying to squeeze the exhaust that normally flows through two 1 1/4" pipes into an inlet the size of a quarter?!?!?!?!?

GH: I know, squeezing the entire engine exhaust down to a dime sized hole seems wrong. This is the reason the turbo works. This is the nozzle feeding the "pump" and high velocity hot air is the stuff making it spin. The IHI turbo will start to spin fast enough to pump pressure into the intake when your engine is pushing above close to 10 hp. Above ~ 10hp the turbo will start swinging into where it wants to pump more air. This is the compressor "map" thing that will wake up some serious power.

Quote:
I'm just trying to get a basic understanding of what I've started here, as I'm only a high school graduate with a few college hours under my belt.

GH: Happy to help... only trying to guide you away from the mistakes I have already made!

Quote:
and I would still go for the drawn through setup without intercooler. it's simple, it work and the carbon seals are just required for extra longevity.

GH: You could try this, but without carbon seals, drawing thru a carb into a turbo is quite dangerous. The reason is, you are bringing mixed fuel into the turbo where it passes next to the hot flaming exhaust stream. The only thing keeping them separated is the carbon seal. Without the carbon seal, mixed fuel can slip thru the sleave bearing and explode in a big way! I am not discouraging you from trying stuff, I just hate injury!

[smog]

Without the carbon seal, mixed fuel can slip thru the sleave bearing and explode in a big way! I am not discouraging you from trying stuff, I just hate injury!

the sleeve bearing is in a constant flow of motor oil. so any fuel getting through the "cold side" seal will get mixed with the engine oil and end up in the sump.

[smog]

the sleeve bearing is in a constant flow of motor oil. so any fuel getting through the "cold side" seal will get mixed with the engine oil and end up in the sump.

oupss I wasn't right, the sleeve bearing is in a pressurized constant flow of oil so if the seals go bad, the oil is get to the cold-side. No way the fuel will ever go to the exhaust side.

I have 2 GT1749 on the bench. But instead of the regular wastegate, the pressure is controlled by variable nozzles in the turbine. Both were good for 180whp and 360 lb ft of torque @ 1800rpm on a 1900cc diesel engine (dyno tested)

edit :

and watch out when you buy a turbo. buying a GT15 is like buying a F-150 ; there's a sh!t load of options. You can get a F150 with the 3.7 v6 and another f150, same color with a 5.4 v8. Same thing with the turbo; you have to know what s inside and get the boost maps for the compressor and turbine inside the turbo you want. you can get MANY size of compressor/turbine in the GT15 frame.

[Stonewall]

Okay, so I'd like to revive this thread and idea. I still have the same engine, and the same goals in mind, but this time I may be willing to spend a little more. I DO NOT want a different, more ideal engine or a supercharger on a Vanguard! The whole idea here is to turbocharge what I have. Let's get some ideas and opinions rolling!!