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Author Topic: Ace GT Head Project  (Read 87094 times)

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ace.cafe

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Reply #30 on: October 03, 2014, 04:42:34 pm
Had the meeting at Mondello's.

They are a little busy right now, and they won't be able to start on it until later in the month.

It was decided to go specifically with the 87mm bore(535). That is the stock displacement of the GT, and the other UCE bikes can be bored out for the 535 piston. The whole valve and porting thing revolves around the bore size, and it just wasn't suitable to try to make a "one size fits both bores" kind of thing, so it will be 87mm bore only. This was a pretty important matter that affected the whole design, so we had to make the decision about that.

All the other things were discussed, but some of the things like valve angle and such will have to wait until they get it all programmed into the computer, which they won't get done until later in the month, and also get a few grand of my money to get them started with the development of the programming.

They were non-committal about the actual cost per unit, which is understandable because they have not actually made one yet, but they still seem to think they can do it for around the same prices as our other roller rocker head conversions, so until I find out otherwise, I have to stick with that estimate.
Just to be clear, this is not going to cost similar to the non-roller-rocker conversions which would use the standard rockers and stuff like that. We will still offer the basic type head work to use with the standard rockers for the low cost like we have been doing. But the billet head with roller rockers is going to be in the price neighborhood of our other roller rocker heads. If you need to know what price range that is, please email me or PM me.



mattsz

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Reply #31 on: October 04, 2014, 05:33:35 am
When we get the figures more firmed-up, people can contact me about it, because I have a general policy to not directly discuss our pricing here on the forum.

Yeah, I figured... which is why I didn't even ask for numbers - just a time-frame.

It was decided to go specifically with the 87mm bore(535). That is the stock displacement of the GT, and the other UCE bikes can be bored out for the 535 piston. The whole valve and porting thing revolves around the bore size, and it just wasn't suitable to try to make a "one size fits both bores" kind of thing, so it will be 87mm bore only. This was a pretty important matter that affected the whole design, so we had to make the decision about that.

Always a bridesmaid...


Otto_Ing

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Reply #32 on: October 04, 2014, 10:47:26 am
i've been looking for the O2 sensor today and did not find it, i assume its a difference in the indian version which i imported. Instead there is some sensor going directly inside the cylinder head. Will the new ace head work with this setup? Anybody knows what this sensor does?


ace.cafe

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Reply #33 on: October 04, 2014, 11:08:26 am
i've been looking for the O2 sensor today and did not find it, i assume its a difference in the indian version which i imported. Instead there is some sensor going directly inside the cylinder head. Will the new ace head work with this setup? Anybody knows what this sensor does?

Our head will work not with that, whatever that is. However that may not be needed. Find out what tjat is, and we can then know if it is needed or not. Since it is not on US models, it may not be a necessary thing..

The india models use open loop EFI which don't have the O2 sensor in the exhaust. Also, the Power Commander systems do not use the O2 sensor either. So you are okay with that aspect of it.
« Last Edit: October 04, 2014, 11:15:28 am by ace.cafe »


Uncle Billy

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Reply #34 on: October 04, 2014, 01:02:55 pm
Not to get too far off the topic here, but let me ask this:  Would a GT motor fit in an earlier frame?  I've always been enchanted by sidecar rigs; I almost bought a Ural but bought my GT instead.  A year or so ago the RE dealer (nicest guy I ever met in a motorcycle shop in 50 years -  Gary at American Harley-Davidson (!) on Erie Street in Tonawanda, NY) had a Rocket with the Steib clone on it which I got to drive.  The only disapointment was that it was really underpowered even with the hack empty.  Seems to me a GT motor with your mods on it would elevate a Royal Enfield rig to "highway useable" even with a passenger in it.  I can't imagine a sidecar would fit on a GT, but if the GT motor would fit in a frame that does accommodate a sidecar...  now there's an interesting project IMO!
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ace.cafe

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Reply #35 on: October 04, 2014, 01:46:09 pm
Not to get too far off the topic here, but let me ask this:  Would a GT motor fit in an earlier frame?  I've always been enchanted by sidecar rigs; I almost bought a Ural but bought my GT instead.  A year or so ago the RE dealer (nicest guy I ever met in a motorcycle shop in 50 years -  Gary at American Harley-Davidson (!) on Erie Street in Tonawanda, NY) had a Rocket with the Steib clone on it which I got to drive.  The only disapointment was that it was really underpowered even with the hack empty.  Seems to me a GT motor with your mods on it would elevate a Royal Enfield rig to "highway useable" even with a passenger in it.  I can't imagine a sidecar would fit on a GT, but if the GT motor would fit in a frame that does accommodate a sidecar...  now there's an interesting project IMO!

No, the UCE is a much shorter overall power unit than the older pre-unit Bullets. They won't match up.
But, not to worry!
We have been building high performance Bullet engines for the older Bullets for years, and we have packages that are very strong for those bikes. Our experience is VERY deep on those older platforms, and we also make the highest performance modification packages for those engines too. We have about 36 of them on the road right now, and some of them have 50k miles on them with excellent reliability. Our Ace Fireball 535 is legendary.

We just had a report on this very forum, in the Classic Bullet section, from one of our Super Fireball owners. He reported breaking The Ton in 4th GEAR on a 5-speed Bullet, going up a long uphill grade, and hitting 6940 rpm. Broke The Ton, and wasn't even in top gear yet. This bike has a carb, with our roller rockers hi-port head, and our cams and piston, and our build specs. It probably has in the vicinity of 50 hp at the crank.
That's the kind of stuff we make.

No problem!
« Last Edit: October 04, 2014, 02:07:57 pm by ace.cafe »


mattsz

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Reply #36 on: October 04, 2014, 02:49:58 pm
Not to get too far off the topic here, but let me ask this:  Would a GT motor fit in an earlier frame?

Earlier frame... meaning a UCE Bullet frame?  If not, please ignore me.

If so, it sure looks to me like it should fit.  But, re-boring a 500 UCE will give you the same 535 that the GT has, yes?



ace.cafe

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Reply #37 on: October 04, 2014, 02:58:51 pm
Earlier frame... meaning a UCE Bullet frame?  If not, please ignore me.

If so, it sure looks to me like it should fit.  But, re-boring a 500 UCE will give you the same 535 that the GT has, yes?

Yes, if he means a regular UCE frame, then you are correct. And yes, 535 is 535, so it can bored for that displacement.


ace.cafe

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Reply #38 on: October 11, 2014, 09:19:04 am
I have a little time this morning, so I thought I'd write what's on my mind.

I'm doing a lot of thinking about getting the most from this upcoming ACE GT Billet Head, and there's a lot that goes into that.

The first matter is the valve angle(stem angle). This is about 26 degrees for each valve on the standard UCE head. It was 40 degrees on each valve in the old Iron Barrel head. As a relative matter, the side-draft inlet system which we have on these engines can get a straighter port into the engine with wider valve angles and deeper chambers. This favors flow, typically.  However, on the UCE, we have a little bit of downdraft angle in the EFI throttle body and injector body, and so that helped to work with the 26 degree valve angle.

Modern heads have even lower valve angles which stand up more vertically, such as 23, 20, 18, 15, 12, 11, 10, etc.. As the valve angles get more vertical, typically the ability of the head to make more power is improved. Most of this comes from the more efficient combustion chamber that is shallower and more compact, for faster and more complete burns, yielding more power. However, as the valves get stood up more vertically, this has some effects on the port, because it either needs to get more downdraft angle, or there needs to be more turn in the port. We really can't get more downdraft angle because we have to hook up to the stock EFI inlet system where it is, or we start to get into clearance problems with the frame. So that's out. Then, we will have to put more turn into the port, making it less of a straight shot in. This requires some really good port work to make the most out of that, but it can be done.
The other thing that happens as the valve angle gets more vertical is that there is less room for the valve size, because they are no longer "tilted" upwards somewhat into the deeper part of the combustion chamber like the
standard head has. We are restricted almost to the bore diameter distance in terms of our valve size combination. We have a 3.425"(87mm) bore in the GT. And we need to have at least a little bit of room between the valves in the center, and have enough room on the edges to avoid flow shrouding by the chamber walls and bore walls. So, it's a tight fit for valve size with these modern valve angles. If we are going to get the flow we want out of these smaller valves and ports with more turn in them, we are going to have to be good at maximizing what we are working with.

So, what the current school of thought says on these matters is to make the exhaust valve as small as you can, and move it over toward the exhaust side as far as reasonable, while still having it work good. Then, that allows you to move the intake valve over more toward the middle, and use a larger size intake valve to make use of all the rest of the room that you got from moving the smaller exhaust valve over. This puts a lot of emphasis on having a very good working exhaust valve and port, which will be high speed because of the smaller size, and that should help with extraction effects during overlap. The exhaust valve is always smaller because the exhaust operates with high pressure to help it get out, which the intake does not have. We just want it to be as small as it can be to be effective enough with our overall flow, so that it isn't a restriction but gives us more room for a bigger intake valve. So, that is the direction we will be going.

« Last Edit: October 11, 2014, 09:26:36 am by ace.cafe »


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Reply #39 on: October 11, 2014, 11:04:18 am
The other thing that happens as the valve angle gets more vertical is that there is less room for the valve size, because they are no longer "tilted" upwards somewhat into the deeper part of the combustion chamber like the
standard head has. We are restricted almost to the bore diameter distance in terms of our valve size combination. We have a 3.425"(87mm) bore in the GT. And we need to have at least a little bit of room between the valves in the center, and have enough room on the edges to avoid flow shrouding by the chamber walls and bore walls. So, it's a tight fit for valve size with these modern valve angles. If we are going to get the flow we want out of these smaller valves and ports with more turn in them, we are going to have to be good at maximizing what we are working with.

Hi Ace,
 I know I have already mentioned it and you gave valid reasons for not doing so, but this is shouting 'three valves', with two inlet valves, to me  ;)
 B.W.


ace.cafe

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Reply #40 on: October 11, 2014, 11:20:41 am
Hi Ace,
 I know I have already mentioned it and you gave valid reasons for not doing so, but this is shouting 'three valves', with two inlet valves, to me  ;)
 B.W.

I get it. :)
But it's $500 more for the custom shaft rocker, and 8 months wait for the custom rocker to be produced. I am trying to avoid those issues on this head.
« Last Edit: October 11, 2014, 11:29:27 am by ace.cafe »


ace.cafe

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Reply #41 on: October 11, 2014, 09:54:53 pm
Okay, well I have done some math, and it appears sound.

The basic limitation is that the 34mm throttle body will be the limiting factor on rpm, and it should be good up to the general vicinity of 6500 rpm, give or take a little. What is going to limit it to that rpm range is the mach index of the air speed thru that throttle body. It can flow enough air to do what we want, but it starts getting into the choked-flow category around 6500 rpm.

Since most people will want to use the standard throttle body and injector body that came with the bike, for ease of use with the PC-V or other ECU modifications, this is going to be the most common arrangement. Also, since most people don't generally run around at 6500 rpm on these bikes, and the advertised peak hp rpm if the stock bike is around 5000 rpm, we can feel pretty confident that increasing the rpm range to 6500 rpm will be enough for most GT riders, especially for use with the stock bottom end.

Okay, so now that we have established the mach index factor as the primary limitation on rpm and power, let's have a look at the math for flow.

34mm throttle body and port entry equals 1.407 square inches area.
It has been established long ago by Superflow Flow Bench company that the max flow that you are able to get at the normal 28" water column vacuum that these flow benches operate at, is 146 cfm per square inch. So, 1.407 square inches times 146 cfm per square inch equals 205 cfm. That's what the throttle body can flow. We know from previous 535cc Bullet modifications that we really only need about 190 cfm or so to get our target power level, and reach about 6500 rpm with a 34mm carburetor.
So, we need an intake valve size to suit.
It looks as if we could fit a 1.7" intake valve into this chamber with nearly any valve angle we choose. So, let's do some math on that.
A 1.7" valve that is lifted to .500" at full lift has a valve curtain area for flow of 1.7 x 3.1416 x .5 = 2.67 square inches.
Max theoretical flow for that area would be 389 cfm.
But at high valve lifts, the flow discharge coefficient at the valve curtain area is not generally very high. We normally can get between .5 to .55 for a discharge coefficient at that kind of lift. So, we can then take that 389 cfm theoretical max, and multiply by .52 as a middle ground estimate for discharge coefficient, and that gives us an estimated  202 cfm flow out the valve curtain at full lift.

Pretty good match. 205 cfm into the throttle body, and about 202 cfm out the valve into the cylinder at full valve lift. Estimated, based on flow areas involved.
So, it looks like we can match a suitable valve size to the flow capacity of the 34mm throttle body, to make maximum use of the flow we can pass thru the system, using a 2-valve arrangement.
« Last Edit: October 11, 2014, 10:04:00 pm by ace.cafe »


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Reply #42 on: October 12, 2014, 04:35:02 am
I get it. :)
But it's $500 more for the custom shaft rocker, and 8 months wait for the custom rocker to be produced. I am trying to avoid those issues on this head.
Fair comment, Ace and I am not trying to interfere. I am sure you have left 'no stone unturned' and I see you have gone over all the maths and science stuff in great depth. I will watch with interest from the sidelines to see how this interesting project develops ;)
 B.W.


ace.cafe

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Reply #43 on: October 12, 2014, 07:33:46 am
Fair comment, Ace and I am not trying to interfere. I am sure you have left 'no stone unturned' and I see you have gone over all the maths and science stuff in great depth. I will watch with interest from the sidelines to see how this interesting project develops ;)
 B.W.

I'm sure that you know that I greatly value your input.
And that I am in agreement with your assessment from a pure performance point of view. The 3 valve would give more inlet flow at less lift, and would extend the performance envelope of this head.

I'm just making this call based on the economics and convenience-of-purchase issues, so that it is more affordable and accessible to the customers to buy off the shelf at the earliest possible time. And, that it reaches the reasonable goals for performance that people want, at a price that would be within reach of buyers, and utilize much of their existing hardware already on the bike.
Obviously, if I thought the market could withstand a significantly higher price and waiting time, I would move to the multi-valve arrangement. But, if we can do the expected things, such as reach the Ton, cruise at 75mph easily, have very good acceleration and a punchy broad torque curve, at a somewhat affordable price for a very premium kind of product, that has shown to be a successful combination in the Bullet market in the past.

Perhaps in the future, we can take this to the next step with larger inlets and multi-valve for racers or other people who want more, and have a bigger budget. I am certainly not against it at all. But I need to be conscious of the price tag, if I expect these heads to move into the general marketplace. The price will already be high enough as it is, to be somewhat exclusive in the Bullet world.
« Last Edit: October 12, 2014, 07:46:51 am by ace.cafe »


ace.cafe

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Reply #44 on: October 14, 2014, 04:45:04 pm
I'd like to point out that although we feel that no aftermarket cams are necessary for this kit to work properly, we are not against aftermarket cams. It's just that the rocker ratio would need to be different to accommodate higher lift cams, and not exceed the available max lift at the valve. So, since we will have different available rocker ratios, that may very well be possible, and other cams may possibly be used.

I can't speak specifically about any of these cams, because none of the aftermarket cams have emerged on the market yet, so I have no idea what lift height they are going to have. If necessary, it may be possible for us to make a custom valve and spring set-up for even higher lift using these aftermarket cams and our ratio rockers.
We will have to see what specs that the aftermarket cams have, and how it all shakes out for possible use with our stuff.

It's hard for us to plan the possibilities of incorporating any of these other parts from other manufacturers, if we don't know the specs.
If people want to combine these future upcoming aftermarket cams with our stuff, we will do our best to make it happen, if it is possible and has good potential.