Landracing Forum
Tech Information => EFI Questions => Topic started by: moirmyster on August 01, 2008, 04:16:02 AM
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Im just in the procces of fitting a turbo to my honda xr 200,just wondering if it is as simple as plumbing up a pipe from turbo to the carb,then jetting to suit.I have heard from a few people saying,the carb needs to be in a pressurised box,does this sound correct.
any tips or help would be awsom.
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Since you prefer not to read this, I'll just take it down.
There, that's better.
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I don't know if turbos and "simple" can go together. I would recommend you read ...
Maximum Boost by Corky Bell
and
Turbocharging by Hugh MacInnes
and yes your friends are correct that you are going to have to at least make some changes to the carb if it is a blow thru system and that is the system of choice.
Good luck and do you have a turbo picked out for the bike??
Sum
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These seem to be the must read books/authors for turbocharging. Corky Bell's shop is about 5 miles from me, I have hear great thing about him for many years.
Fred
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If you leave the carburetor in the stock location and blow through, the pressure would blow the fuel out of the carburetor, hence the need for a pressurized box.
If you mount the carburetor on the turbo you create a potential explosion hazard because the turbo and all the plumbing has a combustible pressurized mixture.
Other than that, it's just jetting. :-D The carburetor wasn't designed for anything other than non-pressurized running, so modifications have to be made to make it work.
On the other hand, I put a turbo on an Opel Kadett (yeah, a long time ago) with a draw through 38MM Mikuni carburetor. No waste gate. I had minimal tuning problems and put 50,000 miles on it with zero problems before I sold it. The only thing of note was the visible wear on the carburetor inlet from the air flow.
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Im just in the procces of fitting a turbo to my honda xr 200,just wondering if it is as simple as plumbing up a pipe from turbo to the carb,then jetting to suit.I have heard from a few people saying,the carb needs to be in a pressurised box,does this sound correct.
any tips or help would be awsom.
IMO.....
For starters, a four stroke single cylinder is not a good motor to put a turbo on. The exhaust pulses are not close enough to keep the turbo spooled up. A mechanically driven blower, like what Fritz Kott has on his bike, is the way to go. Also don't underestimate the oil requirements for the turbo. I used an extrernal oil pump & tank for my BSA with a Yamaha 650 turbo but still fried the $600 turbo after two runs at Bonneville. I don't know if your motor is gravity fed or has a fuel pump or if you are going to use a blow-through or suck-through set-up. If you put the carb in a pressurized box, you will need to have a fuel pump or the fuel will be pushed back up into the tank. If you use a suck-through set-up that won't be a problem.
On my two attempts on my 500 BSA, I failed to make the turbo increase performance over N/A. I guess I learned a lot and would do it different, and better, if I tried again.
Matt Shuss
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ok so im using a RBH31 turbo preety small.should do the job.
Whats yhe difference bettween a suck through system,or the blow through system,which is the easyest to do and most effective.could any one explain.dont like the idea of a pressurised box.
I think i got oil pressure for turbo sorted us exturnal pump.
Any advice would be sweet.
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Since you prefer not to read this, I'll just take it down.
There, that's better.
Lol sorry that was very usfull info,just after peoples opinoins to see whats a better way to do.
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ok so iv got turbo mounted up and bike running,went with the suck through system managed to get enough oil pressure to the turbo.
it seems to spool up turbo fine got 5psi out off it,but im having bit off trouble tunning it it runs fine down low soon as u get over half throttle it dies,if only use half throttle ot goes fine and revs right out.
so iv tried bigger main jet and smaller jet doesnt make any difference.
iv tried a bigger carb still the same.
any one hav any ideas iv spent days tring to get right.
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Make sure you are getting enough gas through the needle and seat into the float bowl. You may be sucking it dry. Though if this is the problem it should at least run on full throttle for a short time.
Another thing to check with your turbo (won't be causing your current problem though) is that it has the appropriate seals for running under the vacum which it gets with a draw through installation. It will suck oil through if it hasn't.
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ok cool thanks for that pretty sure it getting enough fuel as it got a 38mm carb on it.
the in take seems ok hasnt sucked any oil yet.
Another thing i didnt mention is when i tried to get full throttle flames come out the exhuast,and backfires,that may make sence to someone.
its weard as it feels like it to lean but then feels like it to rich.
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Carb size has nothing to do with it, the needle and seat letting fuel into the carb may not flow as much as the jet, when the jet is basicly being sucked on hard...when boosting
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ok well its not even gettin on the main jet to make any boost to suck bowl dry.
i cant just wind the throttle on full will die,but if wind on slowly only using 1/4 to 1/2 throttle makes boost fine.
so to me its pretty much not even getting on the main jet,just using the pilot and the needle.
could be something to do with my setup not sure.
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I had a similar problem.
Ran great until the throttle was wide open.
I my case it was too small of hotside.
Sam
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38mm is too big. Try the stock carb.
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I too tried the RHB-31 with a 38MM mikuni in suck through configuration on a single cylinder. I would like to know where you acquired a RHB-31 from.
Like others have said, I have experienced first hand destroying the turbo due to oil seal issues, and would suggest running both a separate supply pump and scavenge pump with a separate reservoir for the turbo. I also firmly believe as others have said, that a single cylinder does not lend itself to turbo'd applications because the exhaust pulses are too few and too weak to really make the turbo shine, also consider the pulsations occurring when the intake valve opens and the cylinder is charged, some have suggested a plenum that is at least as big as cylinder volume, of course this leads to the inherent drawbacks of fuel mixing etc with a suck through system, we also tried a BIG turbo on a small 2 cycle and came to the same conclusion that a turbo hurts naturally aspirated performance on small displacement single cylinder engines.
That being said, I intentionally ran the motor way rich, and WFO throttle was the worst performing area by seat of the pants feel, feels like the motor is way too restricted, which it probably is by exhaust backpressure, (using a factory cam). For the fire out of the dump pipe, try retarding the timing a bit, and watch for the turbo oil seals to go away. Install an O2 sensor with meter in the header pipe and take it out for a spin, be leery of plug checks because of oil contaminating the intake charge.
In a perfect world, a blow through, with intercooling and big plenum, is the way to go, but still think the exhaust issues are relevant with a single cylinder
Hope it helps
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thanks for that very interesting.im running 400cc plentum chamber as hav read needs to be double the displacment of the engine.
That was my next thort was the engine to restriced needing over size valves some porting as the exhust port is quite small.
Seems to move enough exhuast gases to spool up turbo.
so what is installing a O2 sensor gonig to tell me.
I got the turbo off trademe.co.nz is a trading site in new zealand.
i beleve the turbo is of a suzuki cappacino 600cc car.
I also for got to mention it gets full throttle fine when not under load may make sence to some one.
I had a similar problem.
Ran great until the throttle was wide open.
I my case it was too small of hotside.
Sam
So i guessing u mean that it may need a bigger dump pipe.
Thanks
scotty
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Anyone know if compressor surge could cause the problem?
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ok so i mucked around today i fitted air filter on it that has seemed to hav fixed the problem :-D something so simple,i didnt think it needed one as thort it needed to suck as much air as poss.
not sure it goes any faster,sounds fast tho lol.
thanks for everyones help,learnt lots.
cheers
scotty
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too small a hot side means too small on the turbine side........
there is no way an engine should make around the same hp
if making positive manifold pressure....and supplying additional
fuel..........
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yea thats true thats what i throught to,if it is any faster maybe like 2 to 5 hp.would need to dyno it or hav a drag with a stock one.
The next thing im going to do is open up the ports,make it flow better im sure that will be a good increase in power.
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too small a hot side means too small on the turbine side........
there is no way an engine should make around the same hp
if making positive manifold pressure....and supplying additional
fuel..........
I am no Smoky Yunick, and would agree unless increasing intake manifold pressure and additional fuel result in efficency decreases, from say pumping losses, (which I hypothesize as quite big on a single cylinder turbo) and positive pressure exhaust during valve overlap.
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A bit of clarification; The hot side intake was smaller than the exhaust pipe. Like trying to exhale thru a straw. Actually made less power than NA. An "expert", who shall remain nameless, claimed it was the perfect size turbo for a sub-liter engine.
The early boost caused a reversion wave out the carb that I could smell at 60 mph. I can imagine holding the throttle open long enough to nearly drown the spark and a flamethrower exhaust. Just a guess.
Sam
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bike is going great still bit of fine tunning but getting there.
ok my next problem is its sucking oil past the seals like i was told it would.
I dont no much about turbos but i pulled to bits looks pretty simple,i was expecting to c some sort or rubber seal but the was just some special seal that clips in strange,doesnt even look like a seal. :?
How can i fix this problem is there a special seal u can get.
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Hope you marked the relationship of compressor wheel to shaft or your balance will be out on reassembly.
Piston ring type seal std, you need a spring loaded carbon seal , sort of thing common in water pumps
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Hope you marked the relationship of compressor wheel to shaft or your balance will be out on reassembly.
Piston ring type seal std, you need a spring loaded carbon seal , sort of thing common in water pumps
No i didnt mark it,do u hav to hav a special michine to balance it,by the looks of it some butcher had already been in there,wether he markrd if not dont no.
Ok cool thanks for that ill have to try track that seal down.
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ok so iv got this bike going really good now,i ported the head and oversize valves,has got heaps more power than a stock one.my problem now is its getting to hot as its making more power.Its hard to keep cool as its air cooled engine.i raced it the other day for about 10 mins and it got that hot it nipped up,let it cool down and its away again.the engine hasnt got a oil cooler so the only thing i could think off is some how hook one up,like with a external oil pump.
has any one got any suggestions.
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Hi you're going basically the right way, and with a few hints I dont forsee to many problems ahead.
On my old Kwak funny bike I used to run the turbo oil system completely independant of the bike, so that I couild control, both the flow and pressure to the turbo. I used a MOCAL external 12V oil pump which gave me the flow, but to much pressure, so I made up my own spring loaded bypass valve. I ended up with around 45 PSI and it would circulate the 2.5 Litre oil capacity in approx 15 secs. You need to make the bore of the return pipe at least 3 times the feed pipe, so that there is no oil pressure build up within the turbo, otherwise this can make any leak past the seal worse. Run high quality synthetic oil for the turbo, such as Mobil1 0W40.
With regard to the exhaust side of things, you want a reasonably large bore pipe from the port to the turbo, and a VERY large pipe on the output and wastegate from the turbo, otherwise you will increas the back pressure to much.
If you cant get a copy of the Mcinnes book let me know, and I can scan in some pages for you..
Neil
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Roller bearing motorcycle engines do not put out enough oil pressure or volume to feed a plain-bearing charger. You want at least 15psi oil pressure at idle for the turbo, and if I remember right, a roller-bearing bike only gets about 8 psi at idle. If you must run from the factory engine oil pump, you should only use a roller-bearing charger.
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Does the carb have a power valve? If it does, you'll have to plump the vac line to the pressure section of the compressor. If not. you will be messing with jets until the cows come home. It bothers me that it runs better with the air cleaner on. When you go WOT after idle and it bogs under load but not off-load; this tells me you don't have enough fuel for the transition. You should get the bike on a dyno with a thermocouple and WIDE-band O2 in the exhaust. Weld your fitting UPSTREAM of the turbo so you don't get weird readings from oil passing the turbo seals.
The turbine inlet needs to be the same size as the exhaust port and tubing. The turbines usually have enough material that you can hog it out a little to get a nice transition. Keep the exhaust moving fast! It sounds like your intake plenum is plenty; that's the area where most of the Harley guys screw up. Extra length in the exhaust between port and turbine might be a good thing.
I hope you are running 2 steps colder on the plugs.
Water injection does great things for air-cooled turbo engines. That can be as simple as a small ABS plastic tank with a valve stem, filter (inside, so it doesn't have to be a high pressure unit), a hobs switch or WOT switch, solenoid and fogger nozzle. Fill it 1/2 full of -40F or -30F windshield washer fluid and then pump to 100+ psi. Vent it when the bike is off.
Nozzle sizing should be calculated so you are giving the engine 1:4 or 1:5 water:fuel.
The water injection will keep the head cooler, allow more timing and it'll keep your combustion chambers clean.
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great stuff guys!!!!!!!!!!!! :-P
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I don't think you need a plenum that is 2X the displacement size unless you are running a "blow through" system. The plenum on blow through is to lessen surges. On a suck through system (I think you said you were doing a suck-through system) you could use a THUNDER JET system. It is popular with S & S carbed Harley dragbikes. I am not sure there is enough vacuum in a small single cylinder application for suck through turbo, but it is a great starting place for a design for a smaller motor THUNDER JET. It allows extra fuel at midrange RPM and gives an S & S carb a third fuel circuit. Hope this helps, Friday
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Hey guys havnt been on site for a while,as i lost interest in project.
thanks for all your input some great ideas.
I got motivated again :-) and this is where im up to.Ok if fixed the over heating problem hooked up a oil cooler seems to work fine.On pump gas it runs mint as.
I am in the prosses of running on methanol it goes really well on it runs alot colder and keeps the air intake ice cold,it goes awsom on the mainjet,but im finding it real hard to tune it on the pilot jet.soon as gets off the gas and wind it on again it bogs really bad.Iv tried smaller jets to huge jets,seems little beter with big jets.
Im running a 1.5mm pilot jet and a 3.2mm main jet.
I was thinking part of the problem is u need alot of compression to make methanol work well.As my engine is only 8:1 compresion ratio.
It doesnt make any boost on the pilot jet.but on the main it makes lots off boost it increases the compression ratio maybe that why it runs fine on the main jet,does this theory sound correct.
I tried running on methanol with no turbo ran like a peace of junk was worse.
All so why would i have to run a spark plug 2 steps colder
some one may hav a idea.
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It sounds to me like it wants more timing.
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It sounds to me like it wants more timing.
So in guessing u mean needs to be advanced or retarded?
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More advance. With the lower compression and alky, you should be running lots of timing. You might have stepped your plugs colder because they appeared a little white or did they have melted electrodes? Too much retard can make the engine run too hot and make the plugs run too hot as well.
A large plenum is a good idea on blow-throughs and sometimes draw-throughs. In a draw-through, too big of a plenum will create fuel drop-out and too little will cause compressor surge. Both hurt performance. If you must run a draw-through, I would match the plenum to the cam. Try to make it "adjustable" by making it too long at first and connect the pieces with rubber hose. Then you can trim one piece a little each time until the power starts to fade in the RPM range you want. Then space the two sections to make up for half of the last cut. Make sure to adjust the jets at each test.
Also, think about the "gas spring effect" in regards to port+plenum length. This can give you some free power in certain RPMs. "helmholtz resonator" or whatever it's called...
Personally, I am going with a blow-through setup on my Sportster so I can run a large plenum and an intercooler.
Let's see some photos, they are worth 1000 words. A large single cylinder engine could have issues blowing it's whole exhaust load into a small turbine housing, especially if it's too close to the exhaust valve. In a multi-cylinder engine, the turbine housing has a chance to take the exhaust in small steps. Compare this to dumping a liter of water down the sink with a large cup versus a bunch of shot glasses filled with water one at a time. The water can still get down the drain in about the same amount of time, but the sink will momentarily back-up with the large dump and flow continuously with the small shot glasses dumped one at a time. You can lessen the effect by having a larger turbine housing or more volume in the exhaust between the valve and the turbine.
As far as compressor oil seals- Ideally, you want a carbon seal. Most turbos come with a piston-style ring seal. You can run the ring style with the blow-through but it's a good idea to have a second throttle butterfly DOWNSTREAM of the compressor that is adjusted to be just a little more closed than the real throttle butterfly, except WOT. This will give you enough pressure delta to keep the oil from getting sucked into the plenum. This idea has worked well for a lot of blow-throughs but I wouldn't attempt it if your bike must spend a lot of time at idle.
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Thanks for that,i think il try fidling with the timing havnt tried that yet.
Il try get some photos up so u can hav a laugh lol.
Iv proble done a million thing wrong.But it runs fine on pump gas so must be doing something right.
Check my spark plug it definetly not to white it a nice tanned coulour.
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hey guys
Had a play round with it the other day done a few jetting changes and adjusted the timing got it running sweet as goes mean :-)
I had it to rich on the pilot jet.
Ill get some pics up for u guys to have a look at.
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ok i have another problem now,as i have made more horsepower,i am wreaking gears in the gear box done third gear as is the most used gear.the dogs are ok just breaking off teeth.iv put a differnent gear box in a 5 speed,standard box is a 6 speed,the 5 speed is ment to be stronger.is there any way of making the gears harder,or any other things i could try.
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breaking off the teeth is a common problem with motorcycle trans... althow i have had billet gears made for my turbo motors the real problem is with the shafts themselves... usually 2nd and 3rd gears are in the center of the trans shafts, under power the shafts flex apart and the power crawls up the tooth face where there is less engagement and ultimately there will be less teeth :-D . harder gear teeth is not the best way to go. i think we made my gears out of 6310 it was the same material used in off shore power boat drives, it takes a shock load much better and then we had them surface hardened for wear (yeah right).. my advise is to have new shafts made. i can give you a recommendation as to someone who can make em for ya but being a really really low production run you are probably looking somewhere north of $2g
Kent
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breaking off the teeth is a common problem with motorcycle trans... althow i have had billet gears made for my turbo motors the real problem is with the shafts themselves... usually 2nd and 3rd gears are in the center of the trans shafts, under power the shafts flex apart and the power crawls up the tooth face where there is less engagement and ultimately there will be less teeth :-D . harder gear teeth is not the best way to go. i think we made my gears out of 6310 it was the same material used in off shore power boat drives, it takes a shock load much better and then we had them surface hardened for wear (yeah right).. my advise is to have new shafts made. i can give you a recommendation as to someone who can make em for ya but being a really really low production run you are probably looking somewhere north of $2g
Kent
As Kent so rightly says, you are going through the weakest links within your engine. You may make the trans strong enough, but then you will start jacking the shafts aparts, thus going thu' cases (I had the same problem on my drag bike)
I would recomend talking to Chris Wiesmann who makes trans for F1, Indy, Power Boats, Drag Racing etc and is very helpfull. His company Traction Products is based in Costa Mesa California
Neil
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ok so iv got this bike going really good now,i ported the head and oversize valves,has got heaps more power than a stock one.my problem now is its getting to hot as its making more power.Its hard to keep cool as its air cooled engine.i raced it the other day for about 10 mins and it got that hot it nipped up,let it cool down and its away again.the engine hasnt got a oil cooler so the only thing i could think off is some how hook one up,like with a external oil pump.
has any one got any suggestions.
Ever thought of running alcohol it should run cooler.
Oz
OOps should have read right to the end
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Neil
Wiesmann makes some pretty nice stuff...i think they get 5 or 6 g's for a kawi trans.... It took quite a while for Steve Rice to get him to finish the zx trans.....i think it would be pretty hard to get him to do something for and old Honda single :-o
kent
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Hi Kent,
I know, I trashed a couple of 4-speeds on my bike, before going over to the 3 speeder. Then I just started trashing cases, in 1 season I went thru' 4 sets of KZ cases :-(
Depending upon the trans design, you could take out top gear and put in a double width 1st :roll:
Neil :cheers:
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ok thanks for the ideas,im not wanting to spend much,as its just a hack around bike.think i might just stick to puting in second hand gears,or splash out on new 3rd and 4th gears,think the gears were quite worn gone through the hardening,more than likley my problem.
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Thanks guys--- my senior CRS I had forgotten this thread
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That's okay, Sparky. The guy is all gone now. Thanks to Peter Jack for tipping me off to the spambot.
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What did I miss :? is none of this info good :?
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You're OK Sparky. The reply directly above yours was a spambot that had gone undetected for a while. You can keep marching in the same direction. :-D :-D :-D
Pete
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Since the oiling system question has come up on this thread; I will post our questions here, to try to keep this all together.
Because we have the Rotax Eng with roller brgs. I have been advised we will have to use a stand alone oiling system. Any suggestions on a pump that has some lift capability to pressure rise the turbo. We am guessing we need about 25 Psi through 1/8" ID
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I have decided to go with RB Racing---they are B'Villers and have a long track record with bikes and turbos .
We have our single cyl Rotax 490 project going on under builds
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Thanks again guy for this forum--I reread the subject---saved me from putting my O2 sensor in the wrong place. It is now just in front of the Turbo
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Sparky,
Only pay RB with a credit card as they have a worldwide history of not sending off orders that were prepaid from around the world, ask Ian King from kingracing in merry old England, last I heard he was not to merry.. :evil: I once was a local company neighbor yo them and asked about a turbo system for a GSXR1100 and was told to send 5K to start and I would be advised of the time needed and what the additional cost would be after I send my 5K deposit.. :roll:
J
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John thanks for the heads up---I did order with a credit card--- we will see if it comes. will watch the charges.