Author Topic: Just got an ATP Turbo kit, now I have lots of questions (Read 4070 times)

JLeather · « **on:** October 03, 2007, 08:50:40 AM »

First of all, to anyone who has one and is runing it, what kind of fuel mileage does the bike get? I know it'll be worse than stock, but how much worse?

Secondly, I know some of the ATP kits were pretty hairy for street riding. The CBX kit, for instance, didn't have a wastegate so when you let off the throttle it would take quite a while for the engine to lose the residual boost. You had to really plan your stops. Is the CB750 kit pretty streetable? If not, what could be done to make it more streetable? Prehaps less boost, or a modern wastegate? Does the system come with a wastegate?

I won't pick it up for another 10 days. It's coming from eBay on a chopper frame. Supposedly it's a 900 kit too, but I wouldn't hold my breath on that one. I guess I'll see. Just wondering what I've gotten myself in to. I assume the turbo oils from the engine galley? Lastly, about how much HP could I expect from a well tuned one on a stock motor (or a 900 for that matter)?

mlinder · « **Reply #1 on:** October 03, 2007, 09:00:04 AM »

Depends on boost.
I'd reckon that you'd have to drop compression for anything more than half a bar.
Just look at it this way, concerning power.
A full bar will, ignoring loss, double the output of the engine.
In reality, there are diminishing returns.
So, assuming half a bar, where X = crank output, and Y = unboosted output.
X = (Y*1.5) - efficiency loss

Aaron J Williams · « **Reply #2 on:** October 03, 2007, 09:24:52 AM »

I'm not at all familiar with the ATP kit for bikes but I do know about turbo systems for cars. Running without a wastegate could be quite hairy and if it doesn't have one you might want to add one in. Fuel mileage will be dependent on several factors like timing, boost pressure, compressor efficiency, engine condition, etc. The turbo is made to run most efficiently in a certain RPM range and if you drive outside of that range often then mileage will suffer. I'm guessing it runs a carb or carbs that are drawn through before the turbo and that setup is much worse for mileage than fuel injection would be. Horsepower in a turbo system is based on boost pressure, more boost=more horsepower. However, if the turbo boosts past it's efficiency range the excess heat generated in the air charge negates any further increase unless an intercooler is added to the system. For cars this point is 8-10 PSI. If you could post pics of the system when you get it and a pic of the compressor map I should be able to tell you where the turbo is most efficient and how to tune the system to make it streetable. The oil feed is most likely going to come from a spacer plate between the engine and the oil filter housing, that's where I would take it from if I was doing it. Oil return may go back to the oil tank or to a banjo style fitting at your oil pan drain. If it goes to the tank it will need a check valve to keep the oil from running into the turbo and all over the ground when the bike is shut off. Finally, bear in mind that an engine running under boost is far more picky about air/fuel ratio than a normally aspirated engine. Engine failure can happen in an instant if it runs lean under boost so make sure your fuel and ignition systems are perfect at all times when running your bike. That said, turbos can be very fun to drive and if tuned right can be very reliable also.

Aaron J Williams · « **Reply #3 on:** October 03, 2007, 09:35:56 AM »

Quote from: mlinder on October 03, 2007, 09:00:04 AM

Depends on boost.
I'd reckon that you'd have to drop compression for anything more than half a bar.
Just look at it this way, concerning power.
A full bar will, ignoring loss, double the output of the engine.
In reality, there are diminishing returns.
So, assuming half a bar, where X = crank output, and Y = unboosted output.
X = (Y*1.5) - efficiency loss

I agree with your assessment but I highly doubt this turbo setup can produce 1/2 Bar (7.25 PSI) efficiently. My guess is that it will work best around 3-4 PSI. Even at 1/2 Bar the compression would have to be lowered and probably timing retarded greatly for the engine to live. Of course the compressor map and turbo specs will tell the tale of it's potential. I'm interested to see how it all works out!

mlinder · « **Reply #4 on:** October 03, 2007, 10:41:10 AM »

well, at 4 lbs boost, assuming you have a perfectly running K0, with no modifications, we are talking 67 crank HP.
With lets say, 80% efficiency on the turbo (this is aircooled, no intercooler, after all), you are looking at 81.7936 crank horsepower at seal level.

Hardly worth all the work of a turbo.

You need to run half a bar just to make it worth it.
Half a bar with the same engine, unchanged, gives you 93.8.
As mentioned, though, you'd probably have to retard timing and lower the compression ratio, which, well, drops the initial crank horsepower, so your total output would be less.

JLeather · « **Reply #5 on:** October 03, 2007, 02:57:58 PM »

Not sure I follow the math on that horsepower calculation. I think it's a bit more complicated than that. Not that it matters, the engine that's coming with it is supposedly a ground-up 900 kit build. And, there is one advantage to a turbo...one carb. I hate syncing and tuning 4 carbs. The turbo makes the fuel distribution good enough to run one carb without a cylinder running too rich/lean because of the distribution. Plus, there's the cool factor. Not sure what I'm putting it in yet. A cafe is a possibility, but I've also got a Harley softtail frame with Honda mounts in it. I'm definitely gonna run it, though.

JLeather · « **Reply #6 on:** October 03, 2007, 03:02:01 PM »

Pics of the kit as it sits now. I'm pickin it up in a week. Gotta drive a good distance.

http://s86.photobucket.com/albums/k113/JLeatherman_CF/?action=view&current=b57a_1.jpg

http://s86.photobucket.com/albums/k113/JLeatherman_CF/?action=view&current=c9cf_1.jpg

Looks like it's got an oil line that comes from the filter and returns to the engine cases.

mlinder · « **Reply #7 on:** October 03, 2007, 03:04:50 PM »

The math is simple.
1 bar is equal to air pressure caused by the weight of air at sea level.
If you are pushing 1 bar with the turbo, you are doubling the amount of air and fuel passing through the engine.
This effectively doubles the output.
As I said, there is the law of diminishing returns, however, and the returns on an aircooled, un-intercooled setup diminish more quickly.
It really isn't any more complicated than that.

gregimotis · « **Reply #8 on:** October 03, 2007, 04:04:28 PM »

Quote from: mlinder on October 03, 2007, 03:04:50 PM

The math is simple.
1 bar is equal to air pressure caused by the weight of air at sea level.
If you are pushing 1 bar with the turbo, you are doubling the amount of air and fuel passing through the engine.
This effectively doubles the output.
As I said, there is the law of diminishing returns, however, and the returns on an aircooled, un-intercooled setup diminish more quickly.

Then you must add in the additional 10-15HP output due to the sheer badness quotient of a big-arsed turbo hanging out of your bike.

Aaron J Williams · « **Reply #9 on:** October 03, 2007, 04:36:54 PM »

So what are you going to do with the rest of the bike once the engine is out?

Geeto67 · « **Reply #10 on:** October 03, 2007, 05:34:32 PM »

from what I remember about atp turbo kits there should be a wastegate somewhere in the system. They were fairly complex for the time but to look at one now it is appallingly simple. If you don't have one a vent to air blow off valave from one of the new generation turbo cars can be welded in (and you will get that turbo woosh when you let off the gas).

I also remember that these turbos were capable of making up to 8 psi on a stock motor, which plays heck with all sorts of stock settings. I think part of the reason you don;t see many of these old turbo bikes around anymore is the owners bolted them to stock motors, cranked up the boost and rode the bike till it ate itself. I would definatly think about having your heads done if you are going to run it, get those #$%*es as free flowing as possible.

Jeff.Saunders · « **Reply #11 on:** October 03, 2007, 05:53:16 PM »

Although not on a Honda, I run an ATP kit on one of my bikes - it's been on the bike since I bought it 5-6 years ago - I've made some major changes since buying the bike...

The first thing I did was junk the Zenith / Bendix carb and go for a 42mm Mikuni HSR42 flatslide. A very nice improvement. The bike also has benefited from a Dyna 2000 ignition, some mods to the oil pan/oil pump, a boost sensitive fuel regulator and more...

Turbo motors need to be built with the turbo in mind. Ideally you need to run low compression turbo pistons. Cast pistons are very weak and will fail if you run any serious boost. Your crank / rods will need to be beefed up.

As to boost, I run at around 6-7 pounds of boost - so basically 1/2 a bar increase. With this setup you can run on high octane pump gas.

Fuel economy - if you are worried about this, you need to sell the kit... 'cause they are not particularly fuel efficient - esp. if you twist the right grip with any frequency.

I've emptied a 3-4 gallon tank in 30 minutes of spirited riding...

Jim F · « **Reply #12 on:** October 03, 2007, 07:29:19 PM »

This Kawi is worth at least 20 more HP just sitting there
that is BAD ASS

very nice indeed

Jim

Sam Green Racing · « **Reply #13 on:** October 03, 2007, 07:33:49 PM »

Jeeeeezz ya don't want to be waisting gas like that,....not at the price you Americans have to pay

Sam.

seaweb11 · « **Reply #14 on:** October 03, 2007, 07:34:38 PM »

Aaron: Love your posts, but the phots of your 2 bikes in each and every one?

Jim F · « **Reply #15 on:** October 03, 2007, 07:47:17 PM »

and sense Sam is worried about gas prices I had better not let him
know the price of 110 race gas that I run in my 836 then

(about 8 bucks a gallon but the smell of race gas in the morning)

its victory

Jim

Sam Green Racing · « **Reply #16 on:** October 03, 2007, 07:58:29 PM »

Sorry Jim, I was being sarcastic

we are having to pay $10 for normal pump fuel

Taxed to the efin hilt

Sam.

masonryman · « **Reply #17 on:** October 03, 2007, 08:27:22 PM »

4.99 for leaded 110, heck when pump gas is $3.00 I have been running the good stuff all the time and a tweaked zx 10 with 140 jets gets thirsty.

I like the idea of a turbo, you'll have to keep use posted. I have been looking around but there's not allot of stuff for the 550's

enough of the high jack back to regularly scheduled program.

Mark

JLeather · « **Reply #18 on:** October 04, 2007, 02:52:37 AM »

Once the motor's out I'm gonna put together a chop out of the spare parts. I've got another engine, and I've even got a front Invader that matches the rear one that's on the parts bike. Sounds like I'm gonna need a 5 gallon tank when this is all said and done.

I'm thinking of starting at 3 pounds or so and working my way up. Perhaps I could make the boost/timing retard easily adjustable so I could crank it way back for long rides and boost it way up for messing around town. Dyna 2000's have an easily adjustable timing curve, and an aftermarket wastegate would make the boost easily adjustable too. Does changing the boost affect the carb jetting, or does it stay pretty much the same regardless of boost (draw through application)?

Jeff.Saunders · « **Reply #19 on:** October 04, 2007, 04:16:20 AM »

Turbo engines are sensitive to change. What's nice about a single carb hung on the side is it's very easy to pull the carb and make changes. With the Dyna 2000 it's nice as you can change the retard settings in seconds - and this makes a difference to the bike. Generally on turbo bikes you only want to run around 30 degrees advance. I vary the timing from 28 degrees to 32 degrees depending on the temperature.

Turbo engines take a fairly long time to come up to full operating temperature, so it can take 3-4 minutes of warm-up and riding before throttle response is clean. And they do run very, very hot...

MRieck · « **Reply #20 on:** October 04, 2007, 05:06:59 AM »

Quote from: Jeff.Saunders on October 03, 2007, 05:53:16 PM

Although not on a Honda, I run an ATP kit on one of my bikes - it's been on the bike since I bought it 5-6 years ago - I've made some major changes since buying the bike...

The first thing I did was junk the Zenith / Bendix carb and go for a 42mm Mikuni HSR42 flatslide. A very nice improvement. The bike also has benefited from a Dyna 2000 ignition, some mods to the oil pan/oil pump, a boost sensitive fuel regulator and more...

Turbo motors need to be built with the turbo in mind. Ideally you need to run low compression turbo pistons. Cast pistons are very weak and will fail if you run any serious boost. Your crank / rods will need to be beefed up.

As to boost, I run at around 6-7 pounds of boost - so basically 1/2 a bar increase. With this setup you can run on high octane pump gas.

Fuel economy - if you are worried about this, you need to sell the kit... 'cause they are not particularly fuel efficient - esp. if you twist the right grip with any frequency. I've emptied a 3-4 gallon tank in 30 minutes of spirited riding...

I agree that the Mukuni 42 is the way to to go. I'd fit a Thiel wastegate and get rid of the original antique unit. There are all sort of boost sensitive controls for timimg retard, H2o injection etc available now. Go on a hayabusa forum.....they are tons of guys running big boost.

Aaron J Williams · « **Reply #21 on:** October 04, 2007, 06:03:27 AM »

Quote from: seaweb11 on October 03, 2007, 07:34:38 PM

Aaron: Love your posts, but the photos of your 2 bikes in each and every one?

FIXED!

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Author Topic: Just got an ATP Turbo kit, now I have lots of questions (Read 4070 times)

masonryman