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Spike
| | Posted on Friday, July 22, 2005 - 12:22 pm: | 
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quote:Porsche used an engine driven fan (engaged all the time) enclosed in an elaborate cooling shroud to force air directly to cylinders and heads that had cooling fins designed strictly for the application.
That sounds remarkably similar to the current XB cooling system. The primary difference would be that our fan conserves power by using an electric fan rather than one driven by the engine. Also, our fan only runs when needed.
quote:Porsche also used a huge oil supply (twice as much for an engine half the size of a typical American water-cooled V8) plus a large oil-cooler that had a significant effect on cooling the engine during operation.
The rumors indicate that the new Buell will have increased fuel capacity possibly due to a longer wheelbase, seems like it would be feasible to increase oil capacity in the same manner. Who knows, maybe they could add fins to the swingarm so it could act as an oil cooler.
quote:That's how they kept temperatures in check on their engine. Without a system as efficient as this to shed heat away from critical areas in the engine, temperatures would be have to be higher.
I think that's the whole key to the XB platform- we already have a simple yet effective and efficient cooling system that exceeds our current needs. With a little of the Buell ingenuity I'm sure the XB could be adapted for a mild turbo setup. |
Djkaplan
| | Posted on Friday, July 22, 2005 - 12:22 pm: |
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"All of those rear engined cars,VW,Corvair,Porsche, all had to have engine driven fans and serious air ducting to get enough air to cool them regardless of turbocharging..."
...and the cooling it provided let Porsche increase power without letting the temperature go beyond design parameters and damaging critical components in the engine.
"...as they were a bit out of the airstream stuck as they were on the backside of the vehicle."
Ahhh, like the rear cylinder on a Sportster engine..., and here we visit the crux of the problem, once again. The cooling provided by the electric fan and simple shrouding on an XB is effective up to a point, but doesn't come anywhere near the effectiveness of an engine powered fan spinning in an elaborate shroud over an entire engine developed especially for this type of cooling. The problem is further compounded by the rear facing exhaust valve in the Sportster (or any Harley) engine. Harley went to the trouble to develop the current XR cylinder head layout after having overheating problems with the conventional XL layout, and that bike wasn't turbocharged. |
Djkaplan
| | Posted on Friday, July 22, 2005 - 12:31 pm: |
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"That sounds remarkably similar to the current XB cooling system."
The principle is the same, but the execution entirely different and so is the effectiveness.
"With a little of the Buell ingenuity I'm sure the XB could be adapted for a mild turbo setup."
I never said it couldn't be done by the factory, I said it wouldn't be done. I've seen lots of aftermarket turbo installations on Harley engines, but these engines aren't built and warranteed by the manufacturer.
Just my opinion, of course. Time will prove if what I believe is true or not. |
M1combat
| | Posted on Friday, July 22, 2005 - 01:06 pm: |
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I pretty much agree that it "wouldn't" be done... but you stated earlier that...
"There is no way with the engine's current architecture that it could pass the heat soak and durability tests for production."
I think we're all in agreement that the factory would probably change a few things around... That's not really the issue here I don't think. I think we were discussing whether or not WE could turbo/super charge OUR bikes and where would the the technical hurdles lie  . |
Djkaplan
| | Posted on Friday, July 22, 2005 - 01:39 pm: |
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I know, I just really enjoy the rousing discussion, especially when we can conduct ourselves as gentlemen. That's really why I'm here all the time, for the great discussions. It's all good stuff! |
Blake
| | Posted on Friday, July 22, 2005 - 03:11 pm: |
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DJ,
You started out by warning that the Buell rear exhaust valve and seat would not endure the effects of heat soak after shutdown in a turbocharged 130 HP configuration.
When asked how the turbo Porches managed to survive that problem way back when, you answered basically that they had improved cooling systems including a fan and an oil cooler.
But that fan didn't continue running upon shutdown, thus there was no help for the heat soak issue you raised in those turbo Porches.
More oil capacity?... If the Corvette's 350 small block V8 achieved the same ratio of oil to cubic inches as a Buell XB9 it would need to carry around 12 quarts of oil. Does synthetic oil help?
Did the air-cooled turbo Porches use synthetic oil back then?
I see you claim that you are not stubborn, but you now change reasoning from your alleged heat soak problem to that of "it's just too much power to keep cool."
Of course I agree, a less robust cooling system or an inadequate cooling system would not cool an engine as well as one that was more robust or more than adequate? Are you saying the XB cooling system is not adequate? Thought you were most worried about the rear exhaust valve/seat during heat soak after shutdown? 
FYI the aft end of the rear cylinder of a Buell XB has an ECM controlled dual-speed cooling fan staring it in the face. The cylinder head has a temperature sensor that is monitored by the ECM. It even runs after shutdown expressly for the purpose of eliminating any heat soak overtemp problems in the rear cylinder head.
The Buell engine is not anywhere near being devoid of natural cooling airflow like that of a rear engined automobile. In fact the XB engine is exposed to natural cooling airflow far more than that of even a front engined automobile.
Engine in a box in the rear of a car versus engine in the XB. Nope, sorry, there is no real equating the two insofar as cooling airflow goes.
And the one glaring fact you seem to miss is that the XB engine is better, more consistently, more evenly cooled than any Buell engine before it. So to use its ducted condition as one reason that it is not so well-cooled is simply backwards.
Yes, I agree, all good fun stuff to discus.
But you are indeed stubborn. Trust me, I know stubborn when I see it. You also like to throw out a lot of absolutes, when in reality you don't really know for sure. That's one of the traits of a stubborn person. Trust me, I know.
I hope Buell does introduce a turbocharged 110-120 RWHP bike some day. Not sure they will, but I hope they do. I also hope that they see fit to develop a turbocharger that is specifically designed to work with the XB.
Curious, what was the HP/cc ratio of the commercially available air-cooled Porche engine? |
Whodom
| | Posted on Friday, July 22, 2005 - 03:19 pm: |
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While searching for info on the XB12X, I ran across this very interesting (and relevant to this discussion) post on Cycleforums:
And as a current HD employee and former Buell sales manager I'm pretty aware of the cooling system for the rear cylinder; as I said, this cooling system works VERY well. With a Snap-On thermal measuring gun we noted a 100 degree drop (yes, I said 100 degrees) in the temperature of the rear cylinder/exhaust area in two minutes after turning the bike off on a hot August day (the rear cylinder cooling fan has a two speed switch once the motor is turned off, and the rear cylinder area is what Buell refers to as 'sealed' so the air drawn thru passes directly over the fins then is routed away from the motor). If anyone wants to call BS I understand, but I saw it myself...I don't know what that sort of temperature varience would do to the longevity of a motor, but that cooling fan has a massive impact.
There's also a very interesting related thread in the Cycle World forums started by a guy who set out to measure the difference in cylinder head temps between the rear head on an HD and the heads on a Moto Guzzi with its seemingly superior arrangement. The results were very surprising:
http://forums.cycleworld.com/groupee/forums/a/tpc/f/47260871/m/4850059521 |
Blake
| | Posted on Friday, July 22, 2005 - 03:33 pm: |
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Some of those "absolutes" I mentioned...
Speaking to the XB forced air ducted cooling system compared to your rear-engined Porche example you state that... "The principle is the same, but the execution entirely different and so is the effectiveness."
How can you possibly know this? The fact may well be that the Buell system is MORE effective. Thus a part-time, on only when needed, small electric fan. Ya think?
"The exhaust seats and valves (the parts that get the hottest) on a 160hp sportbike never get to the temperatures you'd encounter on an air-cooled Sportster engine with a significant increase in power over stock. It's the rear exhaust valve and seat that is the crux of the whole problem."
Please explain how you know this to be fact. The high compression 1,000cc 160 RWHP engine has cooler exhaust gasses than would a 1,200cc 120 RWHP engine? How do you imagine that an engine with 33% more power, 17% less displacement, and 12.5% higher compresion ratio that runs at 50% higher engine speed/RPM will expose its exhaust valves/sets to a less severe high temperature environment?
I don't buy it on account of it makes no sense.
On the reason for the massive cooling system of the air-cooled turbo Porche, namely that it was housed in an enclosed box with virtually zero natural airflow or exposure to ambient air...
Ahhh, like the rear cylinder on a Sportster engine..., and here we visit the crux of the problem, once again. The cooling provided by the electric fan and simple shrouding on an XB is effective up to a point, but doesn't come anywhere near the effectiveness of an engine powered fan spinning in an elaborate shroud over an entire engine developed especially for this type of cooling."
Firstly, no not like the rear cylinder of a sporster engine. The rear cylinder of a sportster engine is nothing like how a rear-engined car engine is boxed in on five sides.
Secondly, so your point is that the cooling system of the XB is not as effective as that for the turbo Porche? How do you possibly have the temerity to make such a statement? Again you spout absolutes without knowing what you are talking about. Suggest you stick to facts, like the fact that indeed the XB cooling system is remarkably effective and that rather than being full-on all the time it adapts as required from no fan, to some fan, to full-power fan forced air cooling. The cooling system of the XB is much more effective and sophisticated than what the Porche had. Remember that heat-soak issue you once thought so important? It is important. Thus the XB provides a cooling system that continues to function even after shutdown. The Porche did not. Which is better?
<sigh>
Fun stuff, but it can be very frustrating debating with a stubborn man.  |
Wyckedflesh
| | Posted on Friday, July 22, 2005 - 03:51 pm: |
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The XB frame is designed to be a cooling duct, forcing airflow along the engine as the bike is moving. Anyone who has ridden an XBS has felt that hot engine air being blown up the insides of their thighs just riding on a very hot day, then get blasted when the fan kicks in. I would not be suprised in the least of you took an XB into a wind tunnel and did a smoke test to show the path of the cooling air and how much it in fatc flows around the engine in stock set up. |
M1combat
| | Posted on Friday, July 22, 2005 - 03:52 pm: |
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Anyone mind if we start thinking in terms of a supercharger (like the Rotrex C-10 or C-15) instead of a turbo?
There are two MAJOR benefits IMO to a super vs. turbo...
We get to keep our exhaust note.
No boost lag.
A supercharger is IMO a far superior solution... especially mid-corner on a bike .
I've been thinking about this and it seems to me that with slight modification of the primary cover, A different front sprocket (one with a pulley to drive the charger built in, a strong bracket attached to two or three of the studs that hold the primary cover on (attached in two places each for six hard points) and running the output up through the intake tract through the frame we could get this done.
It would put the charger in the same place as Hill-Billy's XBK (although I have no idea how they mount it or if it may be mounted to the frame). It also (it seems) would fit right there and aside from the tube running through the cooling scoop wouldn't affect "much". I also propose that we could seal the intake hole in the frame which would force all of the air that does get in to aid in cooling.
Any thoughts?
The only issue that I see (and it's a doozy) is keeping contaminants out of the primary oil... We'll have a belt that needs to be running in and out of there...
This particular piece has an oil pump built in , so I propose that we mount an extra oil cooler under the front fairing (if we can get it in there w/o hitting the fender at full bump. I realize this placement goes against mass centralization and reduction of PMOI, but where else can we put it? Maybe under the airbox cover with one of those cool "hood scoop" covers? It may even be alright to mount it 90* from the original cover like Mike does with the Norris catch can... I can't do that seems how I have the catch can, but it seems like that should work alright... |
Djkaplan
| | Posted on Friday, July 22, 2005 - 04:14 pm: |
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"But that fan didn't continue running upon shutdown, thus there was no help for the heat soak issue you raised in those turbo Porches."
I don't think the seats and valves would be as hot to begin with. I thought I made it clear that the more elaborate cooling system would keep the parts within their operating parameters during engine operation.
"Are you saying the XB cooling system is not adequate?"
I never said or implied that the stock cooling system is inadequate for production. I did imply that it wouldn't be adequate in a turbo application, especially one that made a significant increase in power.
"So to use its ducted condition as one reason that it is not so well-cooled is simply backwards."
Who said this? I certainly didn't. I've stated more than once that it was effective for the job it was designed for.
"I hope Buell does introduce a turbocharged 110-120 RWHP bike some day."
Perhaps they will, but I doubt it will be with the current Sportster engine layout. They wouldn't be able to cool it effectively.
JMO, of course. |
Spike
| | Posted on Friday, July 22, 2005 - 04:21 pm: |
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quote:Curious, what was the HP/cc ratio of the commercially available air-cooled Porche[sic] engine?
Ask, seek, and knock:
1975-1977: 2994cc/260hp= 11.5cc per hp
1978-1989: 3299cc/300hp= 10.9cc per hp
1991-1992: 3299cc/320hp= 10.3cc per hp
1993 : 3600cc/360hp= 10cc per hp
1995-1998: 3600cc/408hp= 8.8cc per hp
The real monster was the Porsche 959 of 1987, it generated 450hp from just 2849cc giving it 6.3cc per hp. However, it was a water-cooled engine.
For comparison:
2003-2005 XB9: 984cc/92hp= 10.7cc per hp
2004-2005 XB12: 1203cc/103hp= 11.7cc per hp
While we're on the subject, Porsche is a two-syllable word. Think PORSH-uh not PORSH. |
Djkaplan
| | Posted on Friday, July 22, 2005 - 04:33 pm: |
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I think I answered some of the points you raised in my previous post. You're posting faster than I can answer.
Secondly, so your point is that the cooling system of the XB is not as effective as that for the turbo Porche? How do you possibly have the temerity to make such a statement?
By the fact that the fan is driven by the engine and the fact that the engine was specifically designed for it and the fact that Porsche knew it was adequate enough to support the increase in power that a turbo would add. The XB system is effective for the job it was designed to do - to help cool a moderately powered, normally aspirated engine. Kudos to all involved.
Also, remember that on the XR750, Harley turned the rear cylinder around so the rear exhaust valve would be pointed forward. They tried for one year to make the XL arrangement work for AMA racing, but it couldn't handle the heat it produced. If just changing the material to aluminum could have done it, I'm sure that's all that they would have done.
"Fun stuff, but it can be very frustrating debating with a stubborn man."
Feel free to stop at any point if you're frustrated. I'll hit some more of your points in further posts. I don't have a problem with you getting the last word in, though.
I don't know why you think I'm stubborn. |
Djkaplan
| | Posted on Friday, July 22, 2005 - 04:36 pm: |
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"While searching for info on the XB12X, I ran across this very interesting (and relevant to this discussion) post on Cycleforums:"
I read the statements and don't disagree with any of it. |
Sweatmark
| | Posted on Friday, July 22, 2005 - 06:09 pm: |
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Hmm... discussion above is interesting, but I'm focused on turbocharging an XB as aftermarket project.
Goals: (1) 100HP & 100ft-lb measured at rear wheel; (2) simplest plumbing arrangement; (3) simplest & cheapest A/F control while under boost; (4) avoid engine detonation; (5) have fun & learn something.
Possibilities:
*Garrett small-frame turbo, like GT12 but w/o the watercooling circuit (use oil for it?)
*Intercooler with enough volume to serve as intake plenum (but where to mount it?)
*Rising-rate fuel pressure regulator
*Low boost, say 6-7 psig, for many reasons
*Lower compression ratio via piston swap (along with displacement bump via larger bore)
Sure, I'd love to just buy the HillBilly turbo kit, but for $7k I'd prefer to buy a nice used R1 or Hayabusa. |
Wyckedflesh
| | Posted on Friday, July 22, 2005 - 06:19 pm: |
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I don't think the seats and valves would be as hot to begin with.
How do you figure the seats and valves of a water cooled engine do not get as hot as the seats and valves of an aircooled engine? Combustion heat is still combustion heat. Burnt valves comes from a lean condition which is a fuel problem and not a cooling issue. Porsche needed the extra heavy cooling of the extremely large oil cooler and the ducted fan while the engine was running due to a lack of natural flow of air. I know of Porsche engined racing buggies that underdrive the fan because the engines sitting out in the open air have very little cooling issues while flying at WOT through desert terrain in SCORE race events. Do you happen to recall how long you needed to wait to do an oilchange after shutdown on a VW/Porsche air cooled engine to just be able to have bare skin anywhere near the engines? I can change the oil in my XB at shutdown after a hard ride, as long as I don't touch the header its not burn city. The Xb cooling system could veyr easily deal with a turbo, otherwise all those FX racers last year running 120rwhp should have had engines melt down, but didn't they had other gremlins attack their breakdowns. |
Blake
| | Posted on Friday, July 22, 2005 - 08:03 pm: |
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Spike,
Which of those in your list are for "air-cooled" Porsche engines like I asked.
DJ,
Okay, you now insist that your view is most bolstered by the fact that the Porsche engine utilized a fan driven by the engine and that such a configuration is somehow superior to a non-engine driven fan. And you now claim that heat-soak is not an issue for a turbocharged Porsche because its cooling system was so vastly superior? Somehow the combustion chamber of a Porsche is not exposed to the same internal combustion temperatures that a Buell engine sees?
Okay back to your belief about the fan configuration being so darn important, please explain how such a fan provides better engine cooling than a fan that is driven by an electric motor. I mean given that the XB engine utilizing its far more advanced cooling system intelligence (the Porsches had no such intelligence) is able to run well and run cool in many circumstances without ANY fan at all, only employing the fan when necessary. Would the electric fan be able to run full speed no matter what RPM the engine might be at? How about the Porsche fan? What benefit would it provide idling in traffic? Which is better, a fan that can provide maximum cooling no matter the engine speed, or one that only provides mazimum cooling at mazimum engine speed. Or is that whole heat-soak issue suddenly not important any longer?
You state that the Porsche engine was designed from the start for its application.
Are you saying that the entire engine was designed from scratch with turbocharging in mind? That it has no great similarity to prior non-turbocharged Porsche air-cooled engines?
Are you implying that the XB engine was not designed to meet the demands of severe engine cooling regimes?
Maybe you aren't quite up to speed on the scenario governing the design and implementation of the Buell X-engines. The current Buell engines are Buell engines. They are not Sportster derived engines. The HD Sportsters now uses Buell derived engines and they are better for it. Why? For one, better more efficient cooling.
I just wonder, who the heck are you to say that the current engine was not designed with significant performance enhancements in mind and with the ability to provide adequate cooling for said enhancements. Pretty damn arrogant. Because the XB engine doesn't use an engine driven fan? Which turbocharged and air-cooled motorcycles have ever employed such a fan. Did the prior air-cooled turbocharged engines even employ any type of fan?
M1,
And for the record, the Buell FX racing machines put down closer to 140 RWHP. Good point though. Not a single Buell engine mechanical failure in FX last year. Some sensors and and electrical stuff, but the engines held together well. |
Spike
| | Posted on Friday, July 22, 2005 - 11:26 pm: |
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quote:Which of those in your list are for "air-cooled" Porsche engines like I asked.
To the best of my knowledge all of the 911 Turbos were air-cooled from 1975-1998. They didn't begin using water cooling until the 996 model. |
Blake
| | Posted on Saturday, July 23, 2005 - 01:22 am: |
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So then if Buell were to achieve 8.8cc/HP that would not be anything revolutionary for an air-cooled turbocharged engine.
That would put a turbo Buell XB12 at...
1203/8.8 = 137HP
Sounds good to me, even without that revolutionary ultra-high tech engine driven fan. |
Sweatmark
| | Posted on Saturday, July 23, 2005 - 04:03 pm: |
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OK, now we're talking. For the XB9, how about:
* "1050" bolt-on kit (cylinders, forged pistons)
* 8-9ish compression ratio
* small-frame low/mid AR turbo
* whatever air-to-air intercooler will fit under the aircover, with OE snorkel providing some air flow at speed
* moderate boost
* adequate means of A/F ratio control under boost
Using the 8.8 cc/hp figure, the resultant power output should meet 100 rwhp with parasitic drivetrain losses accounted for. Haven't done the calcs for torque development, but guessing that 100 ft-lbf should be attainable.
Anyone else interested in such a DIY project? We're probably talking about $3k, not counting all the development/dyno time. |
Roc
| | Posted on Tuesday, July 26, 2005 - 01:44 am: |
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Martin,
I've been out of town.
The exhaust outlet from the header is next to the oil lines, which are low and forward on the bike. That all makes it easier to set up I would think. It is also a good place to add weight, if you have to, and it has good air flow. There is already a big sturdy mount there also.
 |
Roc
| | Posted on Tuesday, July 26, 2005 - 01:53 am: |
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Next I see the turbo output being plumbed into an intercooler. I could see ducting being run through the fairing and into the airbox, keeping the front area of the bike smaller, or a cooler in place of the left side air duct. The hole in the frame is another nice thing for the turbo plumbing. For cooling a right side duct could blow on the rear cylinder.
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Roc
| | Posted on Tuesday, July 26, 2005 - 02:08 am: |
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I think heat is a concern but that everything would be fine with a bit of discretion. In the real world wide open blasts probably will not be followed by sudden stops, LEO's insistence aside. |
Djkaplan
| | Posted on Tuesday, July 26, 2005 - 12:33 pm: |
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"How do you figure the seats and valves of a water cooled engine do not get as hot as the seats and valves of an aircooled engine?"
Sorry for the late reply, I didn't see the thread and thought the discussion had ended.
As far as exhaust valves are concerned, they actually spend a considerable amount of time closed during an engine's cycle. Of course exhaust valves will get just as hot in any engine regardless of how it's cooled, but you're not considering the amount of time the valves spend closed, conducting heat to the seats. The seats themselves depend on the engines cooling capability to keep from overheating and staying within a prescribed temperature range. It's been my contention all along that if you turbo-charge a Sportster engine, the simple cooling methods used on the XB will not be able to effectively carry away the heat produced by combustion and the seats and valves will be hotter, too hot for prudent engineers to OK for production. Is that an absolute? Maybe, but you made your own absolutes to defend your statements.
"The current Buell engines are Buell engines. They are not Sportster derived engines."
Then what I said goes for Buell engines. If it quacks like a duck, it's still a duck. |
Djkaplan
| | Posted on Tuesday, July 26, 2005 - 12:43 pm: |
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"And for the record, the Buell FX racing machines put down closer to 140 RWHP."
But we'll never see Buell release one of those for production either. I never said all this stuff wasn't possible, I said it would never be released for production. We'll find out who's right eventually. |
M1combat
| | Posted on Tuesday, July 26, 2005 - 01:35 pm: |
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But we aren't interested in production... Just fun with our already purchased bikes .
I still say we look into a super-charger... wouldn't that mostly solve the fuel issue as well? We would also then be able to keep our exhaust not and quite frankly... the entire system... |
Firemanjim
| | Posted on Tuesday, July 26, 2005 - 03:51 pm: |
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DJ,turboing a motor does not automatically make it run hotter.A turbo works on load,more load produces more exhaust produces more boost.Sitting on my turbo bikes and just revving them produces little or no boost,there must be load and an open throttle.Under most driving conditions you will see little boost.And the turbo is not the big heat adder its the HP,more HP,more heat.Add a good intercooler and your charge air will be cooler than a normally aspirated motor.So not sure where all your worries about excess heat are coming from. |
Blake
| | Posted on Tuesday, July 26, 2005 - 04:42 pm: |
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DJ,
You seem to think that air-to-liquid-to-engine cooling is inherently superior to ducted forced air-to-engine cooling. It isn't. In fact it can easily be horribly inferior in its ability to deal with extreme operating conditions.
Of course exhaust valves will get just as hot in any engine regardless of how it's cooled
If the valves don't get hotter during operation, and if there is no heat-sink issue, then what are you talking about? That more power tends to increase engine operating temperature? No argument there.
Yes, it is when they are closed that heat absorbed by the exhaust valves is shed via the seats to the surrounding metal which is then cooled, be it by air or liquid.
And yes, higher power levels will tend to increase engine operating temperature.
But no, contrary to your mis-perception, the capacity of the Buell XB engine cooling system is not as severely limited as you seem to imagine. Even if it is, then simply mounting up another or a bigger fan or a bigger/better oil cooler would likely solve the problem quite handily.
If Buell never sees fit to release a mildly turbocharged version of the XB, it will not be due to lack of sufficient engine cooling.
Yer stubborn. |
Djkaplan
| | Posted on Tuesday, July 26, 2005 - 04:52 pm: |
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I don't think I ever implied that just the turbo would add heat - the power increase would. Whether you make 140hp naturally aspirated or through intake pressurization (from any method), you will produce more heat.
I'm sure an intercooler would have a cooling effect on the intake side of the engine through convection, but I doubt it would have a significant effect on combustion temperature or the amount of heat transferred by the valve and seat. |
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