Turbo charged with a roller bearing crank

[Reinhoud]

Hi,

 

I was wondering how the turbo builders solved the problem with the low oil pressure on the engines with a roller bearing crank.

Mostly just out of curiosity, and may be I can get an idea for my own bike.

 

I've build 2 oil pumps on my GS1000 engine, one scavenge and one to feed the turbo charger, both driven by the stock oil pump from which I extended the shaft.

A con rod snapped off and ruined the crankcase, so now I'm busy trying to build everything over on another set off crankcases, but castings are never the same, so it's a little bit of a challenge.. 

Edited July 24, 2016 by Reinhoud

[Maggotbreath]

Nothing to add but that's awesome!!!! No, shit, wait, I need more details, You sir are a GENIUS!!!!

Edited July 24, 2016 by Maggotbreath

[slingy1157]

I think generally its a case of over driving the normal oil pump by means of different ratio drive gears off the back of the clutch basket. Either gsx750 oil pump gears or propper turbo bike oil pump gears are available which spin it even faster. As its already got the reduction from the clutch basket its still no where near crank speed. Then place restrictors in the gallerys somewhere to bump the pressure up between the pump and the restrictors for use to feed the turbo. I'm sure someone will be along in the minute with better details. 

Could you build a feed and scavange pump into the end of a crank cover, like the geny cover so  its more swappable between motors?

Or like i think i mentioned in another thread, a belly pan type oil tank for the turbo so the lower oil level enables gravity drain with just an engine driven pressure pump (something internally regulated would be good) which pulls oil from this belly tank? Then engine can be left a bit more how oem intended.

Any way love the look of what youve done there and obviosly proven to be a good system and with maggotbreath, would love to see more pictures on your set up.Would a hunt for cases similar to you last set save major rework?

[Reinhoud]

Thanks.

 

I already have another ratio, I also had a pump (5mm wider) built in from a GSX750 with normal bearings, but even with that the pressure dropped to very low, but higher then with stock pump.

[Reinhoud]

20 hours ago, Maggotbreath said:

Nothing to add but that's awesome!!!! No, shit, wait, I need more details, You sir are a GENIUS!!!!

Haha, what would you like to know?

I'll open a topic soon, scavenge pump is on the crank case again, now the sprockets and support needs to be built in, hopefully that fits straight away..

[Duckndive]

Clever stuff there ........

Most of the old draw thru,s used a Rajay which did not need massive oil pressure ...I,ve used a Garret T3 on a Draw thru without any problems just used 750 oil pump gears ....

I think for a blow thru there are more options with turbos that use ball bearings and need less pressure .....

But an Adult should be along soon to give a better answer ...

[Reinhoud]

I had a oil pressure gauge on my bike, when idling the pressure is not even 2 psi, when you give it some revs it gets may be to 10 psi..

[Reinhoud]

Duckndive, can you give me more info regarding the Rajay turbocharger, please? I've never heard off those, not much info on the net. 

They need less oil as normal turbo chargers?

[slingy1157]

Use an Aerocharger turbo. They dont need any oil supply as they have a built in oil bath that they run on so they can be mounted anywhere.

[Gixer1460]

Nice but not really necessary. The std pump system can be pushed to 30psi which is ok for a plain bearing turbo and if you use a BB turbo you don't need increased pressure anyway. Dino's should have the turbo behind the cylinders then gravity drain is golden - problems sorted LOL!

@ Reinhoud - seriously? They are so oldskool before oldskool was cool! Originally designed to pressurise aircraft cabins back un the 50/60's. They are seriously scarce in A1 condition now and spares are very limited, quite narrow and the lower oil pressure came from the single bearing core so they tend to 'wobble' a bit more. Unless you've got one - I wouldn't go looking for one.

[Arttu]

Normal procedure goes pretty much like Slingy explained. So first thing is to change the pump gears to 750 ones to get about 30% more oil flow. As far as I know there aren't any other gear options commercially available. This flow increase alone doesn't help pressure much. With cool oil it may increase pressure significantly but once oil is in normal operating temp pressure usually drops below 0.5 bar which is way too little for plain bearing turbos (except Rajays).

So next step is to add some restriction to the main oil supply route from the filter and take oil to the turbo before restriction. When done right this will give about 2-4 bar for the turbo and still enough oil for rest of the engine. Easiest way to do this is make a take-off plug in place of the oil pressure light switch. In practice this seem to work well enough but there are still some drawbacks. Oil pressure will be low at low rpm and pressure will vary quite lot depending on oil viscosity and temp. A bit more sophisticated solution would be some kind spring loaded relief valve in place of the restrictor. That should guarantee pretty constant pressure for turbo. Unfortunately making such system would be a bit more complicated.

Here are a couple of pics how I did this take-off years ago.

 

[Reinhoud]

18 hours ago, Gixer1460 said:

Nice but not really necessary. The std pump system can be pushed to 30psi which is ok for a plain bearing turbo and if you use a BB turbo you don't need increased pressure anyway. Dino's should have the turbo behind the cylinders then gravity drain is golden - problems sorted LOL!

@ Reinhoud - seriously? They are so oldskool before oldskool was cool! Originally designed to pressurise aircraft cabins back un the 50/60's. They are seriously scarce in A1 condition now and spares are very limited, quite narrow and the lower oil pressure came from the single bearing core so they tend to 'wobble' a bit more. Unless you've got one - I wouldn't go looking for one.

I never heard of those turbochargers, I'm not looking for one, my system works perfect! Just curious how others solved the problem.

How do you raise the pressure to 30psi? That with an engine at operating temperature I assume?

Edited July 24, 2016 by Reinhoud

[Reinhoud]

17 hours ago, Arttu said:

Normal procedure goes pretty much like Slingy explained. So first thing is to change the pump gears to 750 ones to get about 30% more oil flow. As far as I know there aren't any other gear options commercially available. This flow increase alone doesn't help pressure much. With cool oil it may increase pressure significantly but once oil is in normal operating temp pressure usually drops below 0.5 bar which is way too little for plain bearing turbos (except Rajays).

So next step is to add some restriction to the main oil supply route from the filter and take oil to the turbo before restriction. When done right this will give about 2-4 bar for the turbo and still enough oil for rest of the engine. Easiest way to do this is make a take-off plug in place of the oil pressure light switch. In practice this seem to work well enough but there are still some drawbacks. Oil pressure will be low at low rpm and pressure will vary quite lot depending on oil viscosity and temp. A bit more sophisticated solution would be some kind spring loaded relief valve in place of the restrictor. That should guarantee pretty constant pressure for turbo. Unfortunately making such system would be a bit more complicated.

Here are a couple of pics how I did this take-off years ago.

 

I know the pressure varies a lot, I've done a lot of experimenting. I do have a spring loaded pressure regulator in my system.

If you raise the pressure, is the amount off oil still sufficient? 

[Arttu]

19 minutes ago, Reinhoud said:

I know the pressure varies a lot, I've done a lot of experimenting. I do have a spring loaded pressure regulator in my system.

If you raise the pressure, is the amount off oil still sufficient? 

I run that setup for several years and maybe 20000km without problems. I also measured the pressure from the engine main oil gallery, that feeds the crank bearings, after all these modifications and it was about the same than on stock engine.

Now I'm using a ball bearing turbo that probably would work on lower pressure. But I'm still feeding about 2-3 bar for it to ensure sufficient cooling for the bearings.