Topic: CB550 turbocharging questions: Where to start

[squirley]

I am very interested in adding a turbo to a cb550 project that I have going on.  However, I need some guidance on where to start.  I am not looking into an old system, unless I find a deal that I can't pass up.
I would like to build a system myself, seems much more interesting that way, and it will also give me a chance to use new modern day technology.  So, my question is, has anyone put together a turbo system on a 550 consisting of modern day components. 
I am looking for a place to start, what turbo would work best for the price, what should I look out for, and any more helpful hints; any info/pics would be greatly appreciated. Thanks

[JLeather]

If you're really serious about it, contact Terry at Mr. Turbo.  Very helpful.  The y used to offer a CB550 kit (in the 70's) that was pretty good.  It was a Rajay kit, which is too hard to get parts for now, but atleast gives you an idea of where to start.

[squirley]

I will look into it.  I was actually just reading your post and your turbod project; is it still coming along? 
I would ultimatley like to use some modern day equipment.  I understand how they work, and how to build them; but it is always better to ask questions in advance as I don't want to spend a fortune on discovering what I should have done. I normally buy now and make it work somehow, often turning the pants pocket inside out at the same time.  I find that there is almost alway close to bolt up applications if you take the time to do the research

[dusterdude]

go to www.dragbike.com and join the forum,go to the turbo section and ask away,very helpful folks on there.

[Geeto67]

where to start? Electronic igniton.

You are not going to be doing anything but adding more weight to your bike than it is worth unless you can convert to a tunable electronic ignition. Dyna makes the 2000 which is probably a good place to start looking into how to adjust the ignition. Reliabilty begins with being able to retard the timing enough so you are not burning holes in pistons.

you really should read all there is out there on the web about turbocharging, espically reguarding honda 4 cylinder engines (yes even the car engines) as that will give you a good idea of the science you are working with.

Factories and the aftermarket toyed with carbed turbos for years but it wasn't until you had real adjustable electronic ignition and fuel injection that the potential for a turbo to go beyond mere novelty was unlocked. Even the factory turbo bikes of the 1980s were FI. If you really want to take advantage of the new technology then FI is something you should research as well. There are enough cheap kits out there that it is practical.

personally, if you are on here asking where to begin, me thinks this is a little over your head - unless you want a turbo just for looks. Sure you could just copy an old kit but really 6psi out of one of those rayjay or mr turbo kits was really pushing it.

[JLeather]

I gotta disagree on this one.  There were a number of kits for stock bikes in the 70's and 80's that ran on the old-tech components.  I talked to Mr Turbo and Terry said that I would be fine on a totally stock motor up to about 5 psi.  Stock pistons, rods, points ignition, and cooling system.  5 psi is a pretty good power increase.  I've got an article around here somewhere I can post that was a CB550 test of a Mr Turbo kit in the 70's.  It was a bone-stock 550 with no mods other than the turbo kit.  It was tested against, and destroyed, a pretty modified 836 kit CB750 and it got better gas mileage with the kit than before the kit (65-70 mpg I think is what they said).  Interesting read.  It was a magazine's test.

My rajay kit is capable of 8-10 psi with just wastegate changes.  That's enough for a heavily modified engine.  Draw-through carbs on turbos are fine IMO.

[Geeto67]

just because they ran old tech components doesn't mean they were any good. For the times they were as good as it was going to get, but 6psi isn't really that great for a turbo, heck 10psi isn't that great for a modern turbo.  I am not saying they weren't popular but the scienc back in the day of those old systems makes them trinkets as compared to the efficiency of the new stuff. It isn't the turbo that is largely the problem either, most of the time the turbo (even at 10psi) far exceedes the fuel delivery and ignition timing of a stock bike. 

Lets put this in perspective...in an ideal situation ray jay kits are good for 10psi, in that same ideal situation a modern bike turbo charger is good for 15-25psi (being conservative). A lot of the drag bike and car stuff can get into the 30 and 40psi. Heck my brother's new GTI blows 23psi out of the turbo from the factory. If you can even get those old rayjays to spool up 20 psi, you are way ahead fo your ignition and fuel capabilities, and probably outside the flow capabilities of the cb750 head as well. Comparing the old way of doing things to the new is like comparing a stiff fart to a gale force wind.

If you like chasing 10 extra hp, constantly setting points, doing plug chops, and adjusting needles and jets then the old stuff at 10 psi is for you. At 6psi you are probably picking up just what a bore kit, carbs, and a head job would get you anyway, and they cost about the same.   

As for your article, even the old stuff runs great when new, but it is more susceptible to slighest changes in fuel which can come from sitting, or going to a different station than you are used to. Even a slight change in points caused by normal wear can mean the difference between a solid ride and a religious (holy)piston.

[squirley]

There is no reason why one couldn't run a turbo on a stock engine if they so chose; any combustion engine can benefit from one.
No Mr. Geeto, the turbo is not over my head, and I have had much experience with them actually.  I was just looking for info that was cb550 specific. You never know, as I said before maybe someone has a quick tip on building your own system as in what type of turbo to use that is redily avialable, cheap, etc.   And for your info, I am in the process of F.I.'ing it as we speak.
As a side not, this is not going to be a drag bike, just a fun, interesting, bike.  I don't need to be running huge psi numbers

[Geeto67]

There is no reason why one couldn't run a turbo on a stock engine if they so chose; any combustion engine can benefit from one.
No Mr. Geeto, the turbo is not over my head, and I have had much experience with them actually.  I was just looking for info that was cb550 specific. You never know, as I said before maybe someone has a quick tip on building your own system as in what type of turbo to use that is redily avialable, cheap, etc.   And for your info, I am in the process of F.I.'ing it as we speak.
As a side not, this is not going to be a drag bike, just a fun, interesting, bike.  I don't need to be running huge psi numbers

I am not saying you can't run anything on anything...I am asking what's the point of using "new technology" if you aren't going to go past what the old systems are capabile of. So all your talk about using new technology is pretty wasted if you aren't taking advantage of the real efficency of a new system. And I don't think 15psi is big boost for a turbo motor...not these days. Heck even if you went 10 psi the modern components would improve the overall driveability of the bike over the old turbo systems. If you are going to run 6psi, you get more mileage out of bigger pistons, cam, carbs, and headwork.

you want some cb550 only turbo advice...cb heads are restrictive, look into porting if you are expecting to get any kind or tangible power increase and fully take advantage of the efficency of the turbo.

as for a starting point for the turbo unit...check out subaru wrx turbos from 2002-2003. My buddy is tech at a subaru dealer and he bring them home to use on his modern sport bikes. I have one I was mocking up a cb75 turbo system with.

[James]

Hi guys couldn't help but add a comment, I've got a turbo sitting here I am going to use on my 550 when I get around to it, I had a look around and realised I needed a small turbo that fit a similar sized engine,  it came from a Diahatsu Charade GTi, it's actually an IHI turbo, I've had a look on thier website and its rated from 550cc up to about 1700cc.

By the way the Mercedes Smart Car (City) uses a turbo and they are only 600cc.

Hope this has prompted another avenue of thought.

J

[squirley]

I am mainly looking at new technology due to the availability of products and components. Plus, I am sure that some of the new turbos will be more effiecient and most likely have had a few pounds shaved from them.

[cafebob]

so im building a 750 out right now, with newer components.

I am using IHI turbo RHF4.  Keep in mind if you use a "new" turbo off car, you pretty much have to run blow through, or rebuild the turbo with a carbon seal.  Most turbos today are set up for FI and will need modifications to run in a draw through setting.  Old school rayjay are setup for draw through.  but the older turbos are just that old.  Newer ones spool up faster, are smaller, heat the charge less...unless you really want a old school look, go with a new turbo.

I am blowing through a set of carbs off cb650sc.  They are CV. Blow through is much easier to tune, and gives a better idle and transition.  Draw through systems are a real pain to get to idle right.  They can also be very hard to operate on the street. (they are on or off) Going blow through also allows you to run a intercooler, which is one of the biggest improvements new systems run.  There are almost no cars today that do not come with some sort of intercooler stock. Prices have dropped considerably over the past 10 years.

Dyna 2000, green coils.  Pretty much have too, makes things so much better.  You can pick up a set on ebay for about 100$.  Tuning is easier, reliability, boost retarding of timing becomes a possibility.  Why wouldn't you?

The older kits had a pretty long track between the exaust ports and the turbo.  These days the turbo usually goes right up front. 


I don't know I have seen old rayjay kits going for serious money on ebay.  Just doesn't seem like that good of a deal.  Your paying top dollar for 30 year old technology, and turbo technology has come a long way from the 70's. 

anyway, like everything in life, planning is everything...

bob

[754]

First off I am not a turbo fan.. pun unintended...

But you should consider this,
Quickest factory bike built in the 70,s..Z1R TC.. have run in the 9 sec range when everyone else ran what?... high tens??. And that on a 2 valve motor..  sounds to me like it sorta worked. maybe thats why they still bring money..

I know a guy has an Amen framed 750 Kawi..with a stock turbo motor, and the chopper got into the high tens.. I think that has a small IHI on it.

Anyway, probably a bit raunchier to work with but they did seem to work.. perhaps better than some give them credit for..

A buddy of mine runs ROTREX.. which is like a turbo but belt driven.. pretty high efficiency.. he runs it on a single cylinder Harley.. if you can go faster on a 2 valve Kawi or Honda, you are doing quite well..

[Sam Green Racing]

First off I am not a turbo fan.. pun unintended...

 

[squirley]

I was considering a draw through system before I began the fuel injecting, as it is the simplest to set up, and seems sufficient for what I am looking for.  I am still not totally sure that I am going to continue FI'ing yet.  I am not shooting for the moon on this turbo, I would just like some more kick.
It seems to me that a draw through system would be easier to tune rather than a blow through system.
I realize that I can't use an intercooler with this type of system, but if I put something together that is pushing lower psi's it should be fine.
Cafebob, do you have any pics/more info of the blow through set up?
Thanks 

[cafebob]

i will post them once i get the motor put back together.  I am putting DOHC rods in it this weekend, hopefully. 

Building a fuel injection system for the SOHC bikes would be a very difficult undertaking, I would think.  The motor/ intake is just at the wrong angle.  Most FI bikes have the head at a angle, so that the intake sits almost straight up.  The horizontal nature of our motor would take some real work to build a good intake. 

I have heard from a few people that "drivablity" is a problem with a single draw through carb.  It takes alot of work to get it dialed in.

Alot of old school guys have a knee jerk against blow through because the older CR type carbs can be a real pain to seal properly.  CV's, essentially the newer CV's, are a dream.  The carbs are sealed by design.  Pilot jetting remains the same.  Main jets need a bump, but ironically sometimes a bump down.  Some people run two throttle springs, but it's not always necessary either. "Driveablity" is the same as a unboosted motor, with a smooth power transition as boost comes on. Just apply manifold pressure to the float bowl, use a return type regulator,  a vacuum breaker for idle and sub-boost, and a blow off valve.  Back in the 70's these things didn't really exist in the main stream, but now they are common place with all FI on cars.  20$ at the junk yard and you have most of what you need.

If you are going from the ground up on turbo design, I highly recommend going CV.  someone has to have adapted a 80's set of CV carbs to a 500.  I would think it would be easier than getting a set for a 750.  But then again, I know very little about the 500's.

One other thing, finding a turbo sized for a 500cc motor from a automotive application might be a little challenging.  you might be better off getting a old cx500tc turbo.  those things put out 18-20psi.....

just more to think about.

bob

[Jinxracing]

you might be better off getting a old cx500tc turbo.  those things put out 18-20psi.....

If you decide to go with the Honda CX500/650 turbocharger for your project, send me a PM. My uncle in Washington state has a bunch (14 at last count) of CX500 and CX650 turbos sitting in his shop in various stages of disrepair. Even if he doesn't have a spare turbo unit to sell, he might have a line on where to pick one up cheap.

Just an option, if you decide to go that route.

[Geeto67]

I don't see how FI would be so daunting....for simplicity's sake you would have a single throttle body instead of 4 seperate ones and then just have a car style rail injector that feeds each cylinder with fuel individually. You can use a mass air throttle body off a car (size doesn't matter the same way like with carbs), a megasquirt controller, an o2 sensor, and a temp sender. (at least this is how I have mine laid out on paper).

I always thought the old wayne and sons's log manifold for a cb750 was a good basis for a fuel injection/turbo setup (it was lousy for a carb), nice long cylinder that you could pressurize, and would have bungs for the injectors. If you look at modern honda turbo cars, this is pretty much how the high performance manifolds are anyway.   

[squirley]

Ok, so lets say that I am going to pursue a simple draw through system at no higher than 7psi, can someone recommend a newer style turbo that will allow this?  I ask as I am sure the bearings, and efficiency have increased over the years.
Also, what size/make carb should I look into as I will obviously need to supply more fuel?

Switching to a blow through style setup, has anyone changed their non CV carbs over to CV? This would be a more ideal setup, but may become a pain trying to rework the carbs.

Thanks again

[Geeto67]

From personal expirence: CV motorcycle carbs on a boosted setup usually result in them snapping WFO the moment the throttle is cracked. Not the ideal setup.

[cafebob]

Can be a problem, but it really depends on the set up.  If you are using a vacuum breaker (i think they are called air priority valves too) on the plenum, the carbs are seeing normal air flow until boost.  Depending on how the turbo performs, once the turbo is spooled up and you are seeing pressure you may want them wide open.  But if the transition is too fast i have used double (well actually 1.5) springs to get a little smoother transition.  It also depends on how you have the carbs jetted, I have seen some gsx750's run stock CV carbs....no jetting changes at all, with a vacuum breaker. 

But it can be a problem no doubt.  But the alternative is not that great either...sealing up our stock carbs would be a real chore, i think.  And a single carb is a compromise also...

bob

[Geeto67]

I think that is why EFI makes the most sense if you are going to boost these motors - you don't have to worry about uneven fueling