Turbo on a Bandit ?

[digitaldan]

Hi all

Any reason a Garret GT12 will not work on a B4 ?

http://www.supermotojunkie.com/showthread.php?t=23824

With lots of late nights and R&D offcourse  I reckon the stock compression of a Bandit may be too high for a turbo ?

[andrewsw]

Oh that should be a piece of cake!

seriously though, yeah, I'd say the compression ratio is too high for starters. Don't most turbo charged engines run compression down around 7:1 or 8:1? Also, you'd have to deal with where to stick that compressed air before it gets to the carbs. DRZ is a thumper, that makes it easy. You'd have to fab up some kind of manifold to divide the air between the carbs, or get some way to keep the airbox from blowing it's lid, literally...

And you're going to end up putting all the power up at the top of the curve where the b4 already does pretty well. I think you're better off using jay's overbore kit and doing camarobandito's carb swap.

But it still sounds like fun!

[Mongo]

Seen it on the 1200 (Mr Turbo Kit)

[andrewsw]

That's whack man!

Seriously, how do they handle the intake boost? Obviously, not a stock airbox, but some custom intake stuff.

I ahd a friend years ago who had a Seca650 turbo. He loved and hated it. Loved it because when the turbo spooled up it was a monster. Hated it because of the turbo lag and the fact that it was a dog before the turbo spooled up. He considered it dangerous because of the learning curve in terms of what it took to get it spooled up and having it spool up when you didn't want it.

He always wanted to fit some kind of friction device to it so you could crank the gas, get the turbo going and then start slipping the clutch and get the power from the line. That was surely an idea doomed to spectacular failure. Sadly, that bike ended up as a pool of aluminum when the garage went up in flames.

[Red01]

You could always lower the compression ratio by shimming the cylinder block up from the case.

[tomacGTi]

Most guys on a budget stack headgaskets to lower the comp by a point or so.

I'd imagine there's a manifold to blow into the four carbs. I can only imagine the nightmare of doing that on a B4 though.

[camarobandito]

Pretty wicked idea but I dont think even I would attempt that one on old carbzilla!  I'm not saying it couldnt be done, but with all the things you would have to change and fab I dont think it would be worth it. If I remember right our comp ratio is around 12:1 stock, with a 15 psi boost that would turn it into about 24:1 when the turbo spools up, the engine will turn into a hand grenade on wheels. You would have to lower the comp ratio to no more than 9:1 (preferably 7:1 or 8:1). You couldnt do that with just shimming the head, you would need custom pistons made and definately a stronger crank, not to mention having to add a fuel pump, upgraded cooling system, upgrade the final drive, stronger clutch + gearbox, running AV gas, and all the doctor bills + hospital visits for when the turbo spools up when you dont want it to, it would not be worth it. Engine life would decrease dramatically so add that in. It works on the 1200 and those old secas, but our motors are very different than those. I dont want to sound all negative, but in my opinion it isnt worth the time, $, and wouldnt be safe. Just my .02 cents I will step off my soap box now

[crazycletus]

Ok this one has really caught my attention. I noticed the waste gate in the picture so that fixed one question. To be honest with you I think something could be learned from the 1981 pontiac firebird T/A. Although it was a real POS pontiac did manage to find a way to time the boost in conjunction with a carb and no ECU to control the time bomb. If I remember it was a 301ci motor (V8). To make my point perhaps some research on the pontiac will provide some direction on how to make carb zilla breath fire and not metal chunks!

2 more cents!

Good luck!

[Bartjan]

Although the B4 has a stock compression of 1:11,8 thats not what the real compression is. Thanks to the large timings of the valves the real compression ratio is much lower.
Also it is very easy to lower it by using multiple gaskets under the cilinders (wouldn't recommend using multiple headgaskets... especially with a turbo) and intercooling and/or water injection is a commonly used problem solver here.

Also if it were me doing it I wouldn't use stock carbs, but replace them with a single carb. A custom inlet and exhaust would have to be made anyways.

Main problem with using a turbo on an engine like the B4's is that is has a very wide rev-usage. So a turbo which is good for the lower rev-range won't provide much boost at higher rpm's and a larger turbo would give a big lag, but lots of added power in higher rpm's.

Using a variable turbo (which I think the GT12 is) reduces this problem a little, but not enough for the rpm-range the B4 works in.

Maybe Herr Tod has something to say about this 

[gsxr400 racer]

If you want it build it... but throw lots of money at it

[JmuRiz]

Good point, would be cheaper to get the big-bore kit and forget the turbo.

But if you want to do it and be WAY different, go for it.

[Banditmax]

Big bore + turbo would be the best more cc's to help low end turbo spool but still have that top end boost.

[Vidrazor]

Just get a larger bike. I don't think you'd ever miss it. Of course, if you want to take it on as a challenge, then as Jay said it's all about how much you want to spend. Personally if I was going to go that route, I'd do it with a superharger, if such a beast exist for bikes. I studied supers and turbos years ago when I almost became a race car driver, and turbos never rang right with me. Superchargers, while technically not as efficient, seemed as though they were more appropriate for the objective.

I'll tell you though, if you could pull it off either way, and somehow make it clandestine to some degree, it would be a total riot to pull next to some squid on a Gixxer, CBR, Ninja, or Monster 6-something and blow his mind out.