Steventatt builds a 220 HP CBX

Hey, what projects are you planning or preparing for? CBX, other motos, workshop, WHATEVAH!
steventatt
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Re: Steventatt builds a 220 HP CBX

Post by steventatt »

dyno run
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Re: Steventatt builds a 220 HP CBX

Post by EMS »

That's, no doubt, an impressive Dyno chart, Steve! I like the torque curve even better than the horsepower one. Nice and flat between 7,000 and 9,000 rpm! That thing must pull like a monster :mrgreen:

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Re: Steventatt builds a 220 HP CBX

Post by EMS »

Syscrush wrote:
EMS wrote:Unless the top of the piston is shaped significantly different than the stock piston - which doesn't look like it is in the picture - a compression ratio of 10:1 could only be achieved by modifying the combustion chamber and making it larger, i.e.: taking it from 21 to 25 cc. This is not some mysterious issue, it is just plain math.
Couldn't a spacer or thicker base gasket between the crankcase & cyl accomplish that? I think that's a common mod with the turbo crowd.
A thicker head gasket would definitely increase the compressed volume and lower the compression ratio, but that, again would work against the objective to achieve power and you could not make 4cc per chamber, which is the volume of approx. 4 dies. Frankly, "behind the scenes", I have been scolded for my "doubting Thomas" attitude, but I have worked on internal combustion engines all my life and as a big part of my job and I can tell you, with 1300cc and a compression ratio of 10:1, you are NOT making 200hp. Look at some examples:

Suzuki Hayabusa: 1300cc, 16 valve, 11:1 compression, 160hp and 130 Nm of torque
Kawasaki ZX14R: 1440cc, 16 valve, 12.3:1 compression ratio, 200hp 152 Nm of torque

...and they are all fuel injected.

And if you think a 6 cylinder makes a difference (it does not), look at the specs of BMW's K1600.

steventatt
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Re: Steventatt builds a 220 HP CBX

Post by steventatt »

thanks steve.
i have been in touch with my engine builder, i have asked him if we can get any more power out of my old cbx,
he laugh and said how much more do you want...
he has a few more tricks he can try.... maybe we can get the old girl up to about 240hp :handgestures-fingerscrossed:
its only a question of money...
stayed tuned

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Re: Steventatt builds a 220 HP CBX

Post by norzilla »

Hi All...

Just to shine a little light where light is deserved. Hugh Robinson from Robinson Precision Engines in Bathurst, NSW in Australia is the go to guy for building monster size and power CBX motors. I have just had him build my 1425cc CBX motor for the cafe racer I built. The motor runs a set of CR Smoothbore, PowerArc ( triple spark) Ign, Hydraulic clutch conversion, custom alloy rods, ceramic coated pistons, custom pipes, custom cams, fully ported heads etc etc blah blah. The motor will make well over 200hp when dialed in. I just need to replace the clutch I fried doing a few initial power runs on the dyno while doing the base set up on the motor.

Unfortunately my engine is about to be dwarfed by Hugh's latest CBX destined for his personal bike , weighing in at 1500cc and sporting Hugh's own throttle body fuel injection set up.
I am told that 1500 is as far as is humanly possible with a CBX with a std stroke crank. Oh and did I mention that size does matter and its not cheap, but damn it IS worth it!

If anyone wants more details on these big motors, drop Hugh an email at robtool2@bigpond.com

Cheers
John
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steve murdoch icoa #5322
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Re: Steventatt builds a 220 HP CBX

Post by steve murdoch icoa #5322 »

Cool cafe, John.
Maybe you could start a separate thread with some more details and a link to your site.
I have followed the progress you have posted there starting with the frame build.
btw...no Wellies allowed! haha.

https://www.facebook.com/video.php?v=10 ... =2&theater

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Re: Steventatt builds a 220 HP CBX

Post by EMS »

Very interesting! Enlarging the CBX's displacement has been on the "to-do" list for many CBXers almost since the beginning. I have seen a few motors that have been taken to around 1500cc, but not without custom made cylinder blocks. I am currently fiddling with a 72mm bore in a stock block and it is not all that easy.
A 1500cc motor with the stock stroke will have a 77mm bore. Here is a picture of what a 77mm bore would mean to a stock block. I dare to say, you may run out of room for liners. Would like to know what Robinson does. :think:

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Re: Steventatt builds a 220 HP CBX

Post by Jeff Bennetts »

EMS wrote:Here is a picture of what a 77mm bore would mean to a stock block. I dare to say, you may run out of room for liners. Would like to know what Robinson does. :think:

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I wonder if he's using a custom aluminum block with electroplated cylinder bores and eliminating the liners altogether?

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Re: Steventatt builds a 220 HP CBX

Post by NobleHops »

Could you get away with that in an air-cooled motor Jeff?
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: Steventatt builds a 220 HP CBX

Post by EMS »

That would almost be the only way, going without liners. One could also use a high silicone aluminum alloy block and etch the bores. The hard silicone remains on the surface and you can run a piston in it.
Whatever you do, a stock block is probably the most unlikely to work. :think:

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Re: Steventatt builds a 220 HP CBX

Post by norzilla »

Re the question about whether Hugh uses a stock block, he does, but there are many tech tricks he has developed to make it all possible. He also makes his own proprietary steel barrels for the job. He is working at the very extremes of what is possible with the std engine.

My biggest issue with the 1425cc is that the Rick's Motorsport Hi-perf starter I bought is really not up to the job of starting the motor when hot, even with a 700CCA battery.

Having seen what went into building my motor, this is really not going to be accomplished by any hobbyist engine builder, there has been years of R&D gone into solving all the tech challenges and lots of custom parts, that's one of the things that makes these CBX Rat motors so cool. The man is a genius! :D

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Re: Steventatt builds a 220 HP CBX

Post by norzilla »

steve murdoch icoa #5322 wrote:Cool cafe, John.
Maybe you could start a separate thread with some more details and a link to your site.
I have followed the progress you have posted there starting with the frame build.
btw...no Wellies allowed! haha.

https://www.facebook.com/video.php?v=10 ... =2&theater
Yeh look that is not a bad idea, I will dig the photos up and the info on the bike and start posting. I moved from the UK back to Australia about 12 months ago now so my website has been a little neglected,as I only built part time now. I need to give it a good update as I have a few more bikes to add and a couple I am working on at the moment.
Cheers
John

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Re: Steventatt builds a 220 HP CBX

Post by NobleHops »

That would be awesome, valuable content for years to come. Please do that, and thanks in advance.

:text-goodpost:
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: Steventatt builds a 220 HP CBX

Post by Bob Buehler »

NobleHops wrote:Could you get away with that in an air-cooled motor Jeff?
Long enough for a dyno run LOL.

I know that is going to be one of my problems as it is with other turbo cbxs. You can make the power but then your oil temp goes through the roof and you have to back off while it cools down. There is a reason for water cooling.

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Re: Steventatt builds a 220 HP CBX

Post by EMS »

The specific question was about running WITHOUT liners in an aircooled engine and should not be more difficult than running with. While heat dissipation is generally a problem in high power motors, it concerns the cylinder head really, not the block so much. As a rule of thumb, the energy that is being supplied to a gasoline engine in form of C mHn molecules is converted equally three ways: - usable power, - heat dissipation through the engine and - heat or energy loss through the exhaust. Considering this, if you make 200hp of performance power, you have to get rid of the equivalent of 200hp of energy through engine cooling. That's roughly double of what the stock motor of the CBX does.

I would really like to see some detailed pictures of a stock block with 77mm bore. No matter what sleeves are being used, you would need probably at least 1mm wall thickness. There will be so little aluminum left between the sleeves, I am afraid it will crack. But what do I know.....I am just a hobbyist... :think:

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