Topic: Theoretical discussion CB 750 making more horsepower.

[PeWe]

...and you can 3d print head in metal now. It is just to expensive to do it. 3d printed Al and Ti have same strength as cast counterparts....after you can temper them to T6 state.... But current price for printing 100cm3 of titanium is around 2500eu... and head is around 10000cm3
...

fun fact... space X is printing majority of parts in there engines. Also there is no modern jet engine without 3d printed parts the primary part being compressor/turbine blades...

An Industrial robot that weld like a 3D printer?
3D CAD/CAM system, transform the code to program modules with correct targets sent to the robot controller.
I have seen an installation where they shaped boat models to correct shape created on a PC 3D program by grinding soft material in this way, 15 years ago.

[gschuld]

This is all pretty interesting. 

It may be worthwhile definining the end use.  For strictly racing purposes, or also useful for street gas engines and street bike use.

Regarding racing only, a N/A 1162 was pushed to just under 9 second 1/4 mile times in a 500lb or so all up slick bar chassis racer, over 30 years ago.  This translates to what, around 135-140RWHP.

That’s a lot for our motors(especially the bottom end, being that the original engines were designed to handle the around 45-50 or so RWHP they actually produced).😳. Straight port, splayed big valve mods seem to be the farthest that a factory head can stand.  Are we looking for more than this, or are we looking for a limited series of heads produced to match that power?  Is there enough market for such a thing, even if it was even vaguely possible to do and sell them at like $4,000+ a head.  How many guys are interested in spending $15,000 plus on a fire breathing(relative to a Sohc cb750 anyway) engine by the time it’s done?

It seems the bench racing aspect of this as a technical discussion is cool, but from a practical standpoint... one off straight ports head mods seems to service that limited need for the few willing to go that far.  Perhaps I am underestimating the demand.🤔

George

[MessnerMoto]

...and you can 3d print head in metal now. It is just to expensive to do it. 3d printed Al and Ti have same strength as cast counterparts....after you can temper them to T6 state.... But current price for printing 100cm3 of titanium is around 2500eu... and head is around 10000cm3
...

fun fact... space X is printing majority of parts in there engines. Also there is no modern jet engine without 3d printed parts the primary part being compressor/turbine blades...

An Industrial robot that weld like a 3D printer?
3D CAD/CAM system, transform the code to program modules with correct targets sent to the robot controller.
I have seen an installation where they shaped boat models to correct shape created on a PC 3D program by grinding soft material in this way, 15 years ago.

https://en.wikipedia.org/wiki/Selective_laser_melting

[calj737]

Is there enough market for such a thing, even if it was even vaguely possible to do and sell under like $4,000 a head.  How many guys are interested in spending $15,000 plus on a fire breathing(relative to a Sohc cb750 anyway) engine by the time it’s done?

Perhaps I am underestimating the demand.🤔

George

Limiting my reply to this only: $4,000 for a HiPo head, even for an SOHC is actually not really out of the realm of whats often spent currently to get a stock head to its meager best. Consider:

New valves, guides, and machine work, porting, intakes, studs, towers, etc. I love Mike dearly, and his work is absolutely spectacular. But it is also not cheap, but it is NOT priced on par with its actual value. He should be charging more, and would get it if it were his sole livelihood. His work is that good.

I dare say there are many with more than $8k in their motors, and some with more than $12k. To think folks wouldn't pay $4k for a CNC'ed head that extended the HP of these bikes would be myopic. They only haven't because they can't currently.

This is my personal opinion, but I strongly believe there are more than enough buyers for these modern, improved heads. So get cutting, Mike! 

[gschuld]

Cal,

I TOTALLY agree with your thoughts on Mike’s work.  I’m proud to be a repeat customer.  And if he charged what he is truly worth, even less of us could afford the fruits of his labor.

As I said perhaps I underestimate the amount of potential buyers.  Mike has poured considerable effort and money into those beautiful and proven billet big bore cylinders, but I’m thinking he isn’t planing on retiring off the profits of the resulting sales.

Creating clean sheet new cylinder heads are orders of magnitude greater of a challenge I’d think.  $4000 was likely a wildly low estimate, but who knows.  I can’t begin to keep up with all the technology available today.

I didn’t mean to come off as a glass is half empty type, hell my day job basically involves designing and creating over the top things for clients on a regular basis.

George

[PeWe]

Kawasaki head possible to modify? Cut, weld together to get same distances between bores?
See head as separate 4 combustion chambers with ports, "just" mount them on each bore....
Valves a little bit bigger
http://cavanaughracing.com/kzdata.html
http://cavanaughracing.com/Porting.html

[simon#42]

there is some very impressive technology available these days and ideally if money was not a consideration we could use it to make a beautiful cylinder head . but do we really need it ? as yossef rightly said my suggestion of making patterns then casting a head is very old fashioned but it is also effective and very cheap . once the patterns are made you could turn out a raw head for under a hundred pounds . there would still be a few hours of machining to be done but it would be a very cost effective solution . an added advantage for racing is it would still look very stock and could be used .

here is an engine made without cnc or 3d printers

[MRieck]

Is there enough market for such a thing, even if it was even vaguely possible to do and sell under like $4,000 a head.  How many guys are interested in spending $15,000 plus on a fire breathing(relative to a Sohc cb750 anyway) engine by the time it’s done?

Perhaps I am underestimating the demand.🤔

George

Limiting my reply to this only: $4,000 for a HiPo head, even for an SOHC is actually not really out of the realm of whats often spent currently to get a stock head to its meager best. Consider:

New valves, guides, and machine work, porting, intakes, studs, towers, etc. I love Mike dearly, and his work is absolutely spectacular. But it is also not cheap, but it is NOT priced on par with its actual value. He should be charging more, and would get it if it were his sole livelihood. His work is that good.

I dare say there are many with more than $8k in their motors, and some with more than $12k. To think folks wouldn't pay $4k for a CNC'ed head that extended the HP of these bikes would be myopic. They only haven't because they can't currently.

This is my personal opinion, but I strongly believe there are more than enough buyers for these modern, improved heads. So get cutting, Mike! 

  Thanks for the enthusiastic support both Cal and George....porting isn't exactly "glamorous' but your support...and the support of many other people....helps power me through.
Yeah....a nice CNC head would be great considering it would be a fresh start. It would probably be close to Cal's price predication too.
 The billet block gets around 3,000.00 by the time you plate it and buy pistons.

[gschuld]

Right Mike, nothing you are doing is even remotely glamorous🙄😁.  Of all the highly skilled people in the Sohc community, you are entrusted to these...

George

[754]

 I think at 4 to 6K there will be buyers.
 I also think in the long run casting could be cheaper  ...too much metal removal with billet.
That is unless you need absolute strength.
 Of course it will look different, it wil, be taller for sure and making a camcover wil, have to be cost-effective. . I could see a removeable top. 2 pcs.  The tall part maybe cast.
 The other 4,s look closed to each other, no mistaking a cb 750 lower end.
 I can't see using the other 4s head as a starting point, bigger spacing between bores , cylinder studs in 2 rows  not 3 like ours..

[PeWe]

Is there enough market for such a thing, even if it was even vaguely possible to do and sell under like $4,000 a head.  How many guys are interested in spending $15,000 plus on a fire breathing(relative to a Sohc cb750 anyway) engine by the time it’s done?

Perhaps I am underestimating the demand.🤔

George

Limiting my reply to this only: $4,000 for a HiPo head, even for an SOHC is actually not really out of the realm of whats often spent currently to get a stock head to its meager best. Consider:

New valves, guides, and machine work, porting, intakes, studs, towers, etc. I love Mike dearly, and his work is absolutely spectacular. But it is also not cheap, but it is NOT priced on par with its actual value. He should be charging more, and would get it if it were his sole livelihood. His work is that good.

I dare say there are many with more than $8k in their motors, and some with more than $12k. To think folks wouldn't pay $4k for a CNC'ed head that extended the HP of these bikes would be myopic. They only haven't because they can't currently.

This is my personal opinion, but I strongly believe there are more than enough buyers for these modern, improved heads. So get cutting, Mike! 

  Thanks for the enthusiastic support both Cal and George....porting isn't exactly "glamorous' but your support...and the support of many other people....helps power me through.
Yeah....a nice CNC head would be great considering it would be a fresh start. It would probably be close to Cal's price predication too.
 The billet block gets around 3,000.00 by the time you plate it and buy pistons.

Billet block is absolutely leak free too!  This helped me to decide.
Bore a stock cylinder should not be cheap either. Bore it for 76 mm sleeves. Weld the holes between 1-2, 3-4 and bore again? In with liners and bore for the actual pistons. I forgot the machining of bottom before and top after sleeve install.
- Is Billet block really a higher cost?

[calj737]

Billet block is absolutely leak free too!  This helped me to decide.
Bore a stock cylinder should not be cheap either. Bore it for 76 mm sleeves. Weld the holes between 1-2, 3-4 and bore again? In with liners and bore for the actual pistons. I forgot the machining of bottom before and top after sleeve install.
- Is Billet block really a higher cost?

A billet block, and even a "newly made" billet head would be more expensive than compared to a currently available, used original part. Simply due to one exists, the other is newly made.

Whether cast or billet, both will have costs. The molds for castings have to be machined, the cast part needs cleanup afterwards. Greatest benefit to a billet part is tolerances and repeatability of core strength. Casting has as part of its nature, the presence of air pockets. And they are more fragile under certain stresses. Still can be made to him a standard, but CNC machined billets are the Bee's Knees for quality.

[MRieck]

 I think there is more "waste" with the billet block....those 4 holes represent a lot of lost material.

[calj737]

I think there is more "waste" with the billet block....those 4 holes represent a lot of lost material.

A great sculptor removes what isn't needed to reveal the beauty within 

[kmb69]

I think there is more "waste" with the billet block....those 4 holes represent a lot of lost material.

In Mike's case where the billet includes the cylinder "sleeves":
6061 cylinder billet, 4.5" x 7.5" x 17.5", is approximately 58 pounds.
The "holes" only weigh approximately 2.6 pounds each - ~10.4 pounds total.
The material removed for the fins, the cam chain tunnel, and the bottom of the "sleeves" is heavy! 
Compare the weight of the billet to the finished product. 

[MRieck]

I think there is more "waste" with the billet block....those 4 holes represent a lot of lost material.

In Mike's case where the billet includes the cylinder "sleeves":
6061 cylinder billet, 4.5" x 7.5" x 17.5", is approximately 58 pounds.
The "holes" only weigh approximately 2.6 pounds each - ~10.4 pounds total.
The material removed for the fins, the cam chain tunnel, and the bottom of the "sleeves" is heavy! 
Compare the weight of the billet to the finished product. 

All I know is that gaylord is pretty full after a few processes.

[PeWe]

All that lost billet block material can be reused making a head to it

[kmb69]

.....
All I know is that gaylord is pretty full after a few processes.

Comon Mikey, that's not ALL you know!   

[turboguzzi]

here is half of the head you need...

https://www.voxeljet.com/branchen/cases/zylinderkopf-rekonstruktion-fuer-porsche-legenden/

but what is an economically viable solution for a porsche 356 worth upwards of 200K $ (if not double) might not apply to a CB750 worth 10K $ max, with all due respect to our sohcs.

not sure i understood the method, but seems like these guys directly 3D print the sand cores, which makes it even simper to go then to casting, but still, they're talking about putting together eleven separate cores just for a two cylinder head....

but look at the fin spacing, no way a CNC machine could do that at the required depth. 

Eons ago i was involved in redesigning a G50 head for team obsolete, the idea was to simply splay out the valves while maintaining the same contact point with the rockers. Externally you couldnt even notice. Still have the original matchless factory head blue prints in a roll soemwhere.

[Tracksnblades1]

Whether a sculpture or machinist, they're just removing anything that doesn't look like a JMR Billet Block.

[gschuld]

Eons ago i was involved in redesigning a G50 head for team obsolete, the idea was to simply splay out the valves while maintaining the same contact point with the rockers. Externally you couldnt even notice.

Yossef,

The splayed valve angle modification(along with a straight port mod) on the factory Sohc heads allow for some pretty big valves.  Mike Keyte said he managed 39mm intake valves somehow for a big dragbike motor.  Rex, RPE, Byron Hines’ Pena motor, CycleX, FastbyGast, etc all have done this mod with success.

Kenny at CycleX did a weld up straight port/splayed valve head for his hugely successful heavyweight super vintage road racer (915cc I think).

It’s clearly quite a bit of work to modify a factory head that much, but for those willing to travel that far down the road in search of N/A power, it’s the best option out there.

George

[scottly]

Just how much more HP will this theoretical head develop, compared to a stock head with a port job, over-size valves and thin valve stems?

[turboguzzi]

Just how much more HP will this theoretical head develop, compared to a stock head with a port job, over-size valves and thin valve stems?

good question but max HP is just one factor, more relevant to racing, and even then, a drag head useless in road racing not to mention the street.

beside being to design it for having better flowing port WITHOUT needing huge valves, (which promote good torque), i see the main advantage in combustion chamber shape design. if you look at the most advanced commercial 2-valve moto which are the air cooled ducatis (they are still developed here for  supertiwns racing), these have very flat pistons with plenty of squish area (sohc 750 are deep old fashioned hemi)It let's you have much higher CR without detonation, so that automatically gives good torque at all RPM, just higher thermal efficiency.

if a good all around motor is the goal, then a 16 valve head would be even better and still could be concealed in a stock looking casting.

[kmb69]

Just how much more HP will this theoretical head develop, compared to a stock head with a port job, over-size valves and thin valve stems?

One straight port head that I am aware of:
At 10 Inches of Mercury water and .400 Lift:
Intake    110 CFM
Exhaust    92 CFM
Converted to 28 Inches of Mercury water:
Intake    184 CFM
Exhaust   154 CFM
The maximum POTENTIAL horsepower for a head with these specs is 189.2 HP.
Highly unlikely this can be achieved for many obvious reasons.

Corrected. Thank you Scottly.

[kmb69]

.....
if a good all around motor is the goal, then a 16 valve head would be even better and still could be concealed in a stock looking casting.

Very difficult to do as both Piper and Honda found out. The cylinder studs in the SOHC cases don't allow enough room for the valves.
Piper "got around" this with the funky stock studs through the cylinder only, then DOHC placement between the head and cylinder.
Honda's RCB1000, based on the SOHC bottom end, had custom "sandcast" cases with the typical DOHC cylinder stud arrangement.