Hey everyone I am new to the site and was referred here by a member of another site for my project. I have a 1983 xj750 which I am converting over to fuel injection using the microsquirt and then plan to turbo charge. I'm doing a total engine tear down this winter and replacing everything w/ the necessary forged and heat treated parts to handle the increased power. My question is this, I have been researching turbos and I have been looking at a few and was wondering what would be best for my application? I would like to be able to push 20psi max boost. I have been doing some research and was looking at these turbos they go in order of most interest:

K03: most interested

K04
TD04h
TD05h
T04E
T3

GT12: to small i think

I'm really interested in the gt series from garret w/ the ball bearings, advantages disadvantages? Any info or suggestions would be greatly appreciated. I heard there was a motorcycle turbo guru by the name of Uncle Bob on here from a friend. Maybe he could pm me w/ some good info. Ive searched these forums up and down and it seems this site is the best place for turbo talk, and the info is fantastic. Hope to hear some good insight thanks in advance.

bike stock specs:




83 Yamaha XJ 750 specificationsYamaha XJ 750 1983


1983 yamaha xj 750 photo
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1983 Yamaha XJ 750
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General information
Model: Yamaha XJ 750
Year: 1983
Engine and transmission
Displacement: 748.00 ccm (45.64 cubic inches)
Engine type: In-line four
Stroke: 4
Power: 82.00 HP (59.9 kW)) @ 9000 RPM
Compression: 9.2:1
Bore x stroke: 65.0 x 56.4 mm (2.6 x 2.2 inches)
Valves per cylinder: 2
Fuel control: DOHC being converted to tbi w/ microsquirt
Cooling system: Air
Gearbox: 5-speed
Transmission type
final drive: Shaft drive (cardan)

 

Since you are talking about an engine already making 82hp, I would look at something along the lines of the GT2860R. 20psi would put you around 200hp and that's right in the sweet spot for that turbo.

Uncle Bob is indeed the Jedi Master of motorcycle turbos around here.

 

Thanks for the info and quick response . Its nice to have these forums full of knowledgeable people as i am new to the turbo scene. Have you used this turbo before for any applications? Is it pretty easy to spool up? Any other turbo ideas?

 

I would say the k04 or the gt12, I have a hard time believing that it makes 82hp. I have a mitsu 16G on my gsxr1100 which is pretty close to the mitsu's listed so they might be too large.

 

I haven't personally. Here is a good read on a snowmobile running the RS version of the GT2860, so a little bigger turbo than just the R.

https://www.theturboforums.com/smf/index.php?topic=136642.0

There are a lot of turbos in the small GT line, so really you have to know first off what your HP goals are. I wouldn't go as small as the GT12, since it is only rated for .4L-1.2L and 50-130hp. The GT15 at least is rated for 1.0L-1.6L 100-150hp. First off, how wild do you want this bike to be? Second, PM Uncle Bob and do whatever he says, lol.

 

Testchimp, why is 82 hp hard to belive outta a inline 4 750? Your GSXR1100 is prob somewhere around 150hp stock only 350cc more so 82 hp should be right on. My girl rides a dyno'd out ZX6R for track racing (gotta love a woman who loves speed )and I can pretty much keep up w/ her until she really wants to go fast then well.... lol u get the idea. Im ok w/ it though the views better lol. Would the K04 be able to push 20psi and be comfortable and reliable??? What psi are you pushing on your 16G?

Montegod7ss thats a pretty sik link I'm a sled fan myself got a 2003 800 artictank myself lol. I got all the fun mods done but turbo wow! That Nytro screamed straight from that factory that things gotta be all the fun of a trip to hell and back! I just sent the driveshaft and gears out to be hardened and a shaft made 7.5in longer. I'm choppin/bobbin the bike tearin it up from the rubber to the bars. You were pretty much dead on 200 hp would be ideal (then hopefully i can keep up on the straights lol) but +/- 20-30hp would be just fine. I will deff contact Uncle Bob i just wasnt sure if he was cool w/ bein pm'd. Thanks agian for the ideas and info its greatly appreciateI

I knew this website would be bad for my pocket lol i want to turbo everything!

 

I run 8 psi now but ran 16psi when the engine was spent. You might be correct on the power and if so that's preety good. I would think the K04 would make good boost as it will make 25+ on the audi 1.8 if i remember correct. If you figure the audi 1.8 is probably around 80-100hp NA so about the same as your bike and they spool very quick on those cars. Hope that helps?

 

Thanks testchimp i will deff look into it appreciate the help! Ill post some piks when i get the project rollin.

 

Okay, quick simple calculations.
(45 cubes x 9000 rpm)/ 3456(4 stroke) = 117 cfm
117 * .9 (i think ive heard bikes get around 90% efficiency) = 105.3cfm
(14.7 psi + 20psi) / 14.7 = 2.36 pressure ratio
105.3 * 2.36 = 248.508 cfm
248.508 * .069 = 17.14 lb/min <=====That's about what you need at 9k rpm, I'll leave it up to you to plot the lower rpms. I also dont do anything to compensate for pressure drop or heat rise.