Tiny Turbo Project

[JrZook]

Have a project that's air cooled and I have a IHI RHB31 turbo for it (its bloody tiny!!) Now i was wondering if running the engine oil through the small water jacket of this thing would keep it cool enough. I will be running an oil cooler in the mix as well!

Any suggestions/ideas?

Dan

[KiwiBacon]

Water jackets are for shutdown. They don't do much in normal running.

[phat-customs]

not knowing anything about that particular turb, i assume its BB given that its water cooled???

is it defo oil + water cooled?

[JrZook]

Its a IHI RHB31 VZ21, smallest production turbo out there. Yep I does have a water jacket as well as the usual oil inlet and outlet. Heres a few spy pics of my project.




Cheers Dan

[rockcrawler31]

looks like a cool project

Do you have the room for a small water reservoir, pump and cooler?

[tweak'e]

just leave the water connections not connected. as allready mentioned its only for shutdown. lots of 4x4 turbo conversion simply leave it off.

if you really want to use it then connect it straight to a cooler. however don't forget you have to mount the turbo at the correct angle and route the lines the correct way to get the thermo siphon to work.

[JrZook]

just leave the water connections not connected. as allready mentioned its only for shutdown. lots of 4x4 turbo conversion simply leave it off.

if you really want to use it then connect it straight to a cooler. however don't forget you have to mount the turbo at the correct angle and route the lines the correct way to get the thermo siphon to work.

So your saying it should stay cool enough without any liquid cooling with only the lube oil running in it? That would make things simpler! By the way what sort of oil pressure will I need to feed this thing?

Cheers Dan

[tweak'e]

generally the oil does all the cooling and lube duties. i haven't gone into petrol turbo tech for a very long time but i know diesels guys have measure temp change across the water feed and there is no difference.

however being a petrol motor, which typically run hotter EGT's than a diesel, you will need a substantial cool down time if you don't use the water cooling. you may not like having the bike idle for 5 min every time you stop.
it would be a wise idea to fit an EGT guage and see what it does. or even a small temp guage sensor onto the turbo itself to see what temps the turbo does.

it will be interesting to see how you go about doing the exhaust manifold. you want the turbo as close as possible to the exhaust ports, otherwise it could be quiet laggy.

[phat-customs]

Awwww, isnt it the cutest little thing!!!

It'll be very interesting to see the manifold pipework being a V-Twin, side mount turbo??? Hot on the legs.

Does the bike run an oil cooler??? if not, then defo reccomend running one, or even upgrading to a bigger one if theres one from factory. Being so small i assume Ball Bearing, and therefore oil press requirements will be quite low, (4psi??? maybe???) if its just a sleeve/bush bearing setup, the oil pres will be quite higher as the turbine shaft actually runs on a thin layer of oil inbetween the bearing surfaces.

Looks Like a F(*&^ING sweet project :-D

[ferrit]

generally the oil does all the cooling and lube duties. i haven't gone into petrol turbo tech for a very long time but i know diesels guys have measure temp change across the water feed and there is no difference.

however being a petrol motor, which typically run hotter EGT's than a diesel, you will need a substantial cool down time if you don't use the water cooling. you may not like having the bike idle for 5 min every time you stop.
it would be a wise idea to fit an EGT guage and see what it does. or even a small temp guage sensor onto the turbo itself to see what temps the turbo does.

it will be interesting to see how you go about doing the exhaust manifold. you want the turbo as close as possible to the exhaust ports, otherwise it could be quiet laggy.

Which is interesting to read, as the surf guys are measuring coolant temps coming out of the turbo's on 1KZ-TE's and seeing intakes of 80-90 degrees and outlets of 105+ degrees!

[tweak'e]

generally the oil does all the cooling and lube duties. i haven't gone into petrol turbo tech for a very long time but i know diesels guys have measure temp change across the water feed and there is no difference.

however being a petrol motor, which typically run hotter EGT's than a diesel, you will need a substantial cool down time if you don't use the water cooling. you may not like having the bike idle for 5 min every time you stop.
it would be a wise idea to fit an EGT guage and see what it does. or even a small temp guage sensor onto the turbo itself to see what temps the turbo does.

it will be interesting to see how you go about doing the exhaust manifold. you want the turbo as close as possible to the exhaust ports, otherwise it could be quiet laggy.

Which is interesting to read, as the surf guys are measuring coolant temps coming out of the turbo's on 1KZ-TE's and seeing intakes of 80-90 degrees and outlets of 105+ degrees!

LOL actualy it was the surf guys i was referring to that did a fair bit of testing and found no difference (mainly for 2.8 turbo conversions) be interesting to see how and more important when they where measuring.
even some turbo conversion kits come with instructions that its not critical to pumb up the water feed.

with BB turbo's i'm not sure, less oil mneans less cooling.

[tweak'e]

thinking about this a bit more,
whos going to ride a bike into town, then sit on it for 5 min waiting for the turbo to cool down ?

Q. What water flow rates are acceptable for turbo operation?
A. Water-cooling of turbocharger bearing housings has been widely used to enhance bearing durability. It is designed to remove heat from the center housing after the engine is shut down. This is accomplished because a thermal siphon is set up in the center housing. As heat from the turbine housing and exhaust manifold soaks into the center housing, the water is vaporized and rises, drawing in cooler water. This continues until there is insufficient heat to cause the process to continue.

Installation
In order for the water-cooling to function properly, the center housing needs to be installed below the water level in the engine. The water inlet to the turbocharger needs to come from a lower point in the cooling system up to the center housing. The water outlet needs to go from the turbocharger up to a higher point in the system and cannot have any high spots or "traps" in the line.

The center housing has four water fitting locations. Two of these should be selected such that they are on opposite sides of the housing and the water inlet is lower than the water outlet. The other two locations should be sealed off. These items help ensure that the water-cooling will function properly and the necessary thermal siphoning will take place. Please note the inlet and outlet connections for the water hoses on the drawings provided. If the turbocharger were installed without the water lines being connected, the unit will operate at temperatures similar to, or slightly higher than, the current non-water-cooled unit. However, the water-cooled center housings could be run on engine tests without the water lines connected with no adverse effects, provided the engine is cooled down adequately prior to shut down.

Flow Requirements
There are no set flow requirements for the cooling water, since the majority of cooling in the center housing is done by the lubricating oil while the engine is operating. The most important water-cooling takes place after engine shutdown, at which time the flow of water is a function of the thermal siphon and the flow rate is low. Therefore, the water lines to and from the turbocharger can be sized conveniently. The flow restriction through the center housing is negligible and so would not be of concern for the cooling system capacity.

(honeywell turbo tech web page).

[Tiny]

should be interesting to see it come together, got any other details you wnt to share? engine capacity, revs, boost etc

[JrZook]

Thanks for that tech tweak'e. Might see if i can add a water resivour and try to set up a thermal siphoning system to aid in shut down temps.

Still have a heap to do to even get started on the projects but the basics are
Yamaha 250cc V-twin
redline 8500RPMs
std comp 10:1, will bring down to 8:7.1 with 1mm base gasket spacer
hoping to boost 7+psi

Dan

[tweak'e]

what sort of use will it get?
what sort of driving style?

it certainly looks to be an interesting project.

only real curse for a street bike, especially a high revving motor, is the long exhaust pipes will cause a bit of lag. at least with low boost you can get away without an intercooler.

[Tiny]

Thanks for that tech tweak'e. Might see if i can add a water resivour and try to set up a thermal siphoning system to aid in shut down temps.

Still have a heap to do to even get started on the projects but the basics are
Yamaha 250cc V-twin
redline 8500RPMs
std comp 10:1, will bring down to 8:7.1 with 1mm base gasket spacer
hoping to boost 7+psi

Dan

sweet, I have been toying with a turbo on my yamy 650, will be interested to see how it all goes and how you set it up

one thing I want to do is up the gearing a little if I do turbo it and have no idea where to start with that given it is shaft drive

[JrZook]

This is my first play with a turbo project so here are my calculations to check to usability of that turbo, from the map, on the 250.

map -> http://www.ihi-turbo.com/turbo_RHE-RHF.htm

Using 7 psi as the max boost I find the boost ratio (or compressor pressure ratio) to be:

BR = (14.7+7)/14.7
BR = 1.48

Air Flow of the stock engine I get as:

CFM@4000rpm = (0.250*4000*85)/5660 = 15.02CFM or 0.42m3/min
CFM@8000rpm = (0.250*8000*85)/5660 = 30.04CFM or 0.84m3/min

Assumptions made: Volumetric efficiency = 85% generalization of a modern automotive 2 valve head

Doesn't seem too exciting on the airflow vs pressure map on that website but it is still in the lower part of the compressor working area. According to that compressor map 0.5m3/min is minimum required flowrate to produce any boost. This occurs at roughly 4700rpm.

But this does not include the BR value back into the engine. Substituting this value into the CFM equation we get:

CFM@4000rpm = (0.250*4000*85*1.48)/5660 = 22.22CFM or 0.63m3/min
CFM@8000rpm = (0.250*8000*85*1.48)/5660 = 44.45CFM or 1.25m3/min

So it could possibly produce 7psi of boost across half the RPM range of this particular engine, tho I hope the compressor map doesn't actually look like the one on the website in respect to no boost before 0.5m3/min to an abrupt spike to max set point of 7psi of anything after!

Any feedback to this theory and calculations guys?

Cheers Dan