Superchargers

Hi,

I am working on making a supercharger by using the compressor that is found on turbochargers =). THe purpose is NOT for big boost but enough to give 30 hp.

The turbine will be adjusted as to spin Max 32000 RPM It should give some boost ???

What temp can i expect the bearing to have at that type of speeds??

 

[GregLocock]

Automotive turbochargers run at 80000 to 280000 (!!!!!!!!!!!!!!!!!!!!) rpm, so at 35000 rpm they will be running very cool, but probably not producing much boost either. You should be able to find a map of pressure versus speed somewhere on the web, maybe the Garrett website would be a good place to start.

Your big problem will be that the turbo's bearings are not designed to take side thrust, so you'll need to shaft drive it or fit a big bearing to take the belt or chain tension.

Cheers

Greg Locock

 

Greg,

Thanx for youre answer.
Well the compressor is from a k26 turbo. I`v been told they spin at around 70,000 - 90 000 and they deliver 0.7 bar but could be increased.

And since my engine has 160 hp, 0.2 bar is enough to give me about 20 % power increase = 190 hp. I dont want more because then it gets more complicted and cost $$$$

I have discarded the original bearings and ´bought bearings that are good for 40,000 RPM and 120 C.
The only thing ill be using is the compressor and the shaft. All the rest is garbage

I have send the bearings and the back plate of the compressor to a place nearby inorder for them to make the whole bigger and fit the bearings.

Can temp go over 100 C ?? I find it hard to imagine...

regards,

Sam

 

[GregLocock]

I'd guess that the main problem with bearing temp is due to bleed through from the exhaust, which is probably at 700 or 800 degrees C at full throttle. Therefore if you are using the compression stage only you should be fine for temperature, although 120 is probably cutting it a bit fine.

At a rough guess you will get virtually no boost from your proposed setup, it is running at half speed, so only producing half the volume flow, and only 1/4 the typical boost pressure (roughly). Turbine to engine matching is tricky enough, even when the turbine has the correct flow capacity.

Have you looked at the compressor map for your turbine and checked that it will actually flow enough air?

Cheers

Greg Locock

 

[cycle]

Remember to , A good oil supply from your engine will carry a great deal of heat away from the turbo"s bearing. Use the correct diameter line for the oil feed and an ample (read large) line for the drainback to the oil pan.. Good luck with your project. I would like to here more about it when you finish........... Craig

 

Well im not so good at understanding the diagra, you guys are most probably better

http://www.geocities.com/motorcity/street/1859/K26_Audi_2664_691.jpg

It should give some improvment its hard for me to believe it not doing so hehe and i dont want to . Im basically taking care of the supercharger building process.

Then its upp to my mekanik to give me a hand in making it fit. According to my plans i plan to assemble it to reach its around 33000 RPM at around 6500 engine RPM my red line is at 7300

 

[GregLocock]

(If anyone else tries to follow that link just link down from

http://www.geocities.com/motorcity/street

)

Well you can see that the 40000 rpm line is only just above p2/p1=1, so even at 40000 it is struggling to do anything useful.

The contours are of efficiency, the sweet spot for this turbine is a pressure ratio of 1.7 and a speed of 110000 rpm.

For your desired pressure ratio of 1.2 you need to be pulling 47000 rpm at low flow rates, and 80000 flat out. If you look at the axis along the bottom you may be able to work out the volumetric flow rate, which you can then compare with what you want for your engine 1.2*capacity*rpm/60/2 I think.

Good luck






Cheers

Greg Locock

 

But doesnt it also have to do with how much air my engine sucks in ??

For ex. a 1.2 L engine will definetly work quite well with the above plan i have , or not?

I have no idea wha my engine needs but its a 1.9L 16 v


I think ill have to cancell my plan ?