Odd question maybe, but I'm looking for suggestions on where to find a small turbo. A friend of mine is into motorcycle dragracing - which here in Thailand usually means a souped up Honda Sonic. He's already increased the displacement to 200cc, but is looking to go bigger. Either going up to 300cc or adding a small turbo. The 300cc conversion is likely to cost him more than the whole bike did, so I'm trying to help him out by finding some info on small turbos..

eBay has a number of Smart turbo's. Does anyone know if these are any good? I seem to remember a lot of Smarts developing engine problems? Any other small and relatively inexpensive turbo options?

...and small intercoolers perhaps?

The bike currently has a 198cc displacement, 10:1 CR (needs to be lowered) and revs happily to 10,000+ RPM. Ideally looking for about 1 Bar boost..

[Edited on 5/4/08 by akumabito]

I have my doubts as to whether such a tiny engine would be happy having a relatively large turbo strapped to it. Even the Smarts are around 800-900cc aren't they?
Have you considered Nitrous?

I thought the Smarts were 700 cc and didn't rev all that high? Hmm.. You could be right, gotta look that up, brb..

EDIT: First generation is 0.6L turbo, 0.7L turbo or 0.8L turbodiesel..

[Edited on 5/4/08 by akumabito]

Ah I stand corrected - even so, it will take a lot of gas to spin a turbo which is designed for an engine 3 times its size. The losses might make it impractical - at the very least it will have horrendous lag.

Smart turbo is a Garrett GT1241, they are considered a bit small for a 998mini turbo conversion.

Full details including turbo map are here:
http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT12/GT1241_756068__1.htm

Garrett claim it will flow enough for up to 120bhp, but you'll need to do the maths yourself. A bike 200cc bike engine at 10,000rpm will need approximately the same air as a 400cc engine doing 5000rpm, so I don't believe it will be horrendously oversized for the application.

honda made the cx500 turbo (cx650 later)
at the time it was though impossable to turbo charge such a small engine.

The japanese KEI cars used 550-660 turbo engines, with IHI RHB31 and RHB5 turbos. These turbos were also used on the Daihatsu Charade Turbo and Fiat Uno Turbo in the mid '80s.
Is the Sonic a single or a twin? A single cyl turbo is usually harder to get to work well...

I have a rebuild GT20 laying around. Interested?

you dont mention wether its two stroke or 4 stroke either .

I just thought of a good one. Why not go for an electric supercharger! The Turbonator on Ebay might actually give some more power to such a small engine.

turbonator....... come on
he's looking for power not chav-tuning

what about a small positive displacement compressor,
he can calculate everything on forehand and has the ability to run whatever boost he wants. no lag which is good because the turbo would probably just get on spool half way down the straight

the newest eaton series has a very tiny one availeble. called the Eaton TVS R350
it has 350cc displacement per rev so it that's run 1 on 1 at the cranck he'd allready be in serious buisness and it will take very little power to run a TVS on that speed.

there's a Jap Honda four stroke tuning company who even have roots style compressors for 50cc moped engines. don't know what the company name is however, need to ask my brother.

grtz Thomas

[Edited on 5/4/08 by thomas4age]

http://www.evilution.co.uk is the smartie lad

Ooh! A lot of replies so quick! Thanks a ton for the input guys! It's not my bike though, but I'll try to answer as many of the points raised as I can;

@Lippoman: It is a single cylinder engine, 4-stroke. It had a lot of work done already; bigger valves fitted, custom cams, new exhaust, new carb, and a bunch of other stuff..

@Aico: Hmm, those electric superchargers always seemed like a waste of money. Or rather; a typical eBay scam with impossible promises.

But then again, the bike doesn't need all that much air.. let's see.. a promised 250 CFM (probably highly optimistic, but let's run with that for a second..)

250CFM = 7080 liters per minute. At 10,000RPM a 200cc engine consumes 2000 liters of air per minute. I guess in this case it just might actually work, provided of course the airpump has enough power to build up an overpressure. Since it would only have to run for a few minutes max, it could be run off a separate battery, so it won't rob engine power through the alternator..

Still, it doesn't seem very plausible though. If it would really work, I am sure others would've tried it by now..?

@Thomas4age: The eaton supercharger sounds just about perfect. Don't know about the price though. Somehow I doubt it'll be cheap. The alternative he's looking at is upgrading his engine to 300cc, which will set him back about 60,000 THB - About 950GBP installed..

You think you could find out the name of the company that produces those moped compressors? Sounds like a good lead for more info..

Oooh! I just found this site about a DIY turbo installation on a DAX.. apparently the Mitsubishi TD-02 is the teeniest turbo around...

quote:

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Originally posted by akumabito
But then again, the bike doesn't need all that much air.. let's see.. a promised 250 CFM (probably highly optimistic, but let's run with that for a second..)

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Yeah, that's what I figured.. So.. scrap that idea, turbo or supercharger it is..

I still think that nitrous will be more viable. How much power will you absorb spinning up a supercharger? How laggy will a turbo be?
When you are starting off with precious little power you don't want to take any away if you can help it.

I just read turbo's are pretty ineffective in single cylinder engiens because the exhaust pulses are spread too far, especially at lower RPMs. If that's right, I suppose that's another idea to bin.

Nitrous oxide starts to look more and more appealing by now, though there's still something to be said for a small supercharger. Nitrous somehow almost seems like 'cheating'. There's just something appealing about an all-mechanical setup.

Though I suppose purists would say forced injection is just as much 'cheating' anyways..

Can't you just buy a bigger/more powerful engine to chuck in. Probably cheapest option of all

ATB

Simon

Horizontal cylinder engines are pretty hard to find.. most are around 100cc, some go up to about 150 or so, and that's where the playing field for reasonably priced engines seems to come to an abrupt stop. He's already fitted a big bore kit which gives him nearly 200cc..

If you know of a good 200cc+ engine, be sure to let me know though..