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GX200 Turbo project

NewbCarter

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More pictures , and updates soon ..
 

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itsid

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nice blades :D

So I see you're going mikuni there..

am I mistaking or were you planning on an EFI conversion *headscratch*,
and if I'm not... what happened to that?

In any case.. nice.. cute little turbo you got there;
yes please, more pics and infos.. as much and many as you can in fact :D.

'sid
 

NewbCarter

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nice blades :D

So I see you're going mikuni there..

am I mistaking or were you planning on an EFI conversion *headscratch*,
and if I'm not... what happened to that?

In any case.. nice.. cute little turbo you got there;
yes please, more pics and infos.. as much and many as you can in fact :D.

'sid

Yep , draw through setup with a Mikuni clone , 26mm . Tried it out before hand , works very well , but even with the needle all the way down ( highest notch , least possible fuel ) it was still waay too much mixture for a stock GX200.

The G200 threw a rod , thus its of no use . I tried to find a suitable replacement , and i did , but really never got the time to do it properly . This setup is to show it can be done , but with no fancy business .

---------- Post added at 10:27 AM ---------- Previous post was at 10:26 AM ----------

Where'dya get the turbo?

Turbo is off Alliexpress , shipped to me from France , arrived in 3 days . 175 USD , shipping included . (+ since i have some premium membership discounts , final price was around 150 USD ).

---------- Post added at 10:37 AM ---------- Previous post was at 10:27 AM ----------

As of details .... its not that interesting to be honest .

Draw through setup with the mentioned carburetor , a hydraulic pump ( either toroidal or geared ) will be used as a source of lubriaction , with a 120mm watercooling radiator i have leftover from a PC build serving as the oil cooling .

Why the radiator ? Well , the GX200 technically has no oil cooling , and even if the turbo doesnt push much boost ( im aiming at .5Bar , so a relative 50% increase in capacity ) it will still heat the oil up quite a bit , so a radiator is a must .

I was thinking of hiding the radiator in the fan shroud , so it gets the max possible cooling .

So oil flow would go like this : Sump (via the drain plug) -> radiator -> pump suction side -> turbo -> drain back to the hole leftover from the low oil cutoff switch found stock on the GX.

Piping il try to keep as short , especially the exhaust side , the GX will need all the help it can get to spool this turbo up . No intercooler aswell , since if i did my math correctly , the carburetors venturi effect with the fuel being atomized should bring the intake air temperatures down enough so even after being compressed by the turbo , it should remain under safe limits .

No BOV or such either , since it would be throwing the mixture out in the atmosphere .
 

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Close up of the turbine side of things , and the compressor side.
 

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NewbCarter

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Not much pictures so far , have to collect all the components first , and figure out a mount for the turbo , as it is not as light as it might seem to be ( 2,75kg ! ) , so it needs a proper mount .

I will also be going for a different carburetor setup , preferably a flange mount Mikuni (30mm) , with a power jet . The current carburetor fits but does not have a power jet , which i had plans for .

Mainly running the power jet from a seperate fuel bowl / tank , that will be mounted near the carburetor , but will be fed with a water-methanol mix .

Reason why is mainly safety / safeguard from engine knock caused by excess boost / heat in the combustion chamber since i am not so sure the carburetors venturi effect will be enough of a heat soak for the boost level .

Boost will be controlled and monitored via a simple T-fitting between the boost port on the turbo and wastegate actuator , and probably a small ball valve of sorts to act as a leak if i want more boost.

The crankshaft will need to be lengthened another 10mm to accomodate a pulley to drive the oil pump to feed the turbo for lubrication .
 

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Ordered some AN4 braided steel line and some AN4 fittings to test fit on the turbo and pump , to see how it all adds up .

The pump i decided to go for is a cycloid style hydraulic pump with the following specs :
- 0.8cm3 / revolution
- 2000 RPM max
- flow of 1.5L/h at 1800RPM
- pressure range of .2Bar to 5Bar
- 1/8" fittings

I will need to DIY some sort of pressure diverter valve ( was thinking along the lines of a T fitting with a valve on the turbo line while the other T connection goes back to the engine ) as apparently the turbo does not need more than 6 psi of oil pressure ... which i frankly doubt . I will start off at 1 Bar , then drop the pressure down if i notice the seals leaking .

Also ordered a basic analog boost gauge and pressure regulator to be used to monitor and control boost.
 

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Read thru the paperwork that arrived with the turbo ...

Reccomended AN4 line for oil supply , AN10 for drain . Wastegate is 8psi from factory , which is ideal , as i wasnt planning to run much more boost than that .

Apparently (if it can even spool the turbo to that point) its most efficient from 8 to 14 psi , any more and it just spins alot quicker but for much less flow increase.

If the charts are accurate , this turbo can achieve a maximum pressure delta of 2,7 , which to my knowledge means 2,7 times the atmospheric pressure ? Im not too knowledgable on turbo maps.

Fun fact , the little compressor wheel can spin up to 254k RPM .
 

65ShelbyClone

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It is going to burn a lot of oil with the draw-though carburetor. Vacuum is going to pull it past the compressor seal when the throttle is not fully open.

No BOV or such either , since it would be throwing the mixture out in the atmosphere .

A BOV will serve no purpose with a draw-through arrangement. The compressor inlet and outlet are both under vacuum when the throttle is closed so there is pressure to release.

Apparently (if it can even spool the turbo to that point) its most efficient from 8 to 14 psi , any more and it just spins alot quicker but for much less flow increase.

If the charts are accurate , this turbo can achieve a maximum pressure delta of 2,7 , which to my knowledge means 2,7 times the atmospheric pressure ? Im not too knowledgable on turbo maps.

Fun fact , the little compressor wheel can spin up to 254k RPM .

A few things to keep in mind:
- A turbo's mass flow capability is on the horizontal axis of the chart. The pressure ratio capability (8psi = 1.5 PR) is on the vertical axis. You need to estimate what the engine's mass airflow requirement will be at the power you want to make. Match that on the bottom axis with the PR and the point should fall somewhere on the compressor map. If not, the turbo is liable to choke or surge depending on where it goes off the map.

- The turbo is not likely capable of a PR of 2.7. It is marketed as a VZ21 and RHF3, but I suspect it's mostly a copy of an older RHB31 that has a max PR of about 2.0 or 2.2. That said, it's nearly impossible to find reliable information on even the genuine IHI turbos they copied, so maybe I'm mistaken about that.

One thing is for sure, they're small.
https://i.imgur.com/NtSs1Q9.jpg
 

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I heard about the seal issue from other forums ... they were mentioning "carbon positive" type seals , im not familiar with the terminology ...

Im hoping it wont be too much , otherwise the best plan is to go blow through with a carb in the pressure box , but that is quite a bit of extra hastle .

Im no expert obviously , im only hoping it will spool up and make a couple of psi , if it eats a bit of oil well , so be it . At least till the gas doesnt contaminate the oil .

As of any further news , the pump should be arriving soon , and in the meantime i ordered a 6-row oil radiator and some 1/8" NPT fittings for the pump , and M10x1.25 to AN4 adapters for the radiator .

Now for advice .... where should i put the oil drain to ? Current plan is an AN10 line to the crankcase via the hole left by the oil sensor . The second idea i had is to drain back to the valve cover , to offer the valvetrain more lubrication and perhaps cooling due to the extra load ...

Other than that , progress is still slow , i have exams to deal with and waiting on parts ..
 

65ShelbyClone

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I heard about the seal issue from other forums ... they were mentioning "carbon positive" type seals , im not familiar with the terminology ...

Yeah, it's a four-piece assembly much like the seal in a water pump. They began to get phased out in the '80s in favor of dynamic seals, which are more like a piston ring and have lower drag. Unfortunately carbon seals don't exist for your turbo (nor many others).

im only hoping it will spool up and make a couple of psi

It probably will.

Now for advice .... where should i put the oil drain to ? Current plan is an AN10 line to the crankcase via the hole left by the oil sensor.

That is probably the best compromise IMO. The front oil fill hole might also work as it is larger and higher up.
 

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Pump has arrived.... Opened it up for some nude shots :lolgoku:
 

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NewbCarter

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Some progress.

Tested the oil pump after cleaning it, it provides more than enough oil. The drain plug location is ideal for a pickup.

Pics show how the turbo should end up sitting on the engine, probably s bit higher to enable proper draining of the oil.
 

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65ShelbyClone

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I *think* the pickup might work better on the rear of the engine. The crankshaft and is going to be sweeping oil away from the front one.
 

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I *think* the pickup might work better on the rear of the engine. The crankshaft and is going to be sweeping oil away from the front one.

This engine (really cheap clone) apparently only comes with one drain hole .

Also , decided on spending a bit more , and making the engine a bit safer for itself and me . I have a billet conrod , an aluminium flywheel and a stage 2 cam with 18lb springs on the way . Cam isnt much so for safety as it is for airflow , hopefully will be of help .
 

itsid

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cool..

if that happens to turn out well;
I have the funny feeling I know what your next plan is going to be
(we talked about it earlier, right?)

I think it can be done btw... a few tweaks and a good map should be all it takes ;)
But we'll cross that bridge once we get there ;)

'sid
 

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cool..

if that happens to turn out well;
I have the funny feeling I know what your next plan is going to be
(we talked about it earlier, right?)

I think it can be done btw... a few tweaks and a good map should be all it takes ;)
But we'll cross that bridge once we get there ;)

'sid

Yeah, about that. If i manage to clean out this semester, i could get acces to a nice lab where i could do PCBs and stuff.

For the fuel injection, i really want to do a 2stroke, it is more work but i think it would be cool to see.

And not Arduino based, rather on an ST microelectronics MCU, they are beefier than an arduino, and should enable quite precise control.
 
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