PDA

View Full Version : Bristol Hercules Sleeve Valve In Action



DrHerb
11-12-2009, 04:28 PM
I always wondered how a sleeve valve looks like while operating. Now I know! http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Sleeve Valve in Action (http://www.youtube.com/watch?v=EJcxpFTFJPA)

AndyJWest
11-12-2009, 05:06 PM
Interesting http://forums.ubi.com/images/smilies/25.gif Take heed of this though:

Viewer warning: do not attempt to understand this engine on your first attempt. Failure to do so may result in a nose-bleed http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Choctaw111
11-12-2009, 05:14 PM
I would like to know more about how this engine works.

AndyJWest
11-12-2009, 05:33 PM
Suck, squeeze, bang, blow... (http://en.wikipedia.org/wiki/Suck,_squeeze,_bang,_blow)

Waldo.Pepper
11-12-2009, 05:55 PM
Curiously erotic. Or I am a pig.

doraemil
11-12-2009, 05:56 PM
this one is cool:

http://www.youtube.com/watch?v...0JJk&feature=related (http://www.youtube.com/watch?v=pXDw_670JJk&feature=related)

you can see them work the controls

I also liked this too:

http://www.youtube.com/watch?v=_vrvep_YOio&NR=1


the description has linx in it too

Daiichidoku
11-12-2009, 06:04 PM
nice link...found this from the related search

http://www.youtube.com/watch?v...YOio&feature=related (http://www.youtube.com/watch?v=_vrvep_YOio&feature=related)

and this


http://www.youtube.com/watch?v=NSMYjRNQ8Rs&NR=1

Choctaw111
11-12-2009, 06:12 PM
Wow, there are some great movies in here.
Thanks for sharing everyone.

major_setback
11-12-2009, 06:17 PM
I came.

Choctaw111
11-12-2009, 06:20 PM
Originally posted by major_setback:
I came.
TMI http://forums.ubi.com/images/smilies/88.gif

Buzzsaw-
11-12-2009, 06:21 PM
Salute

The engine I think is the most interesting of all WWII varieties is the Napier Sabre H Block 24 cylinder. It also used sleeve valves.

In its final versions this engine produced 5500 hp out of 36.65 litres, far higher than any other conventional type.

For example the Daimler Benz DB605 V12 conventional valve engine series topped out at around 2200 hp from 35.7 litres.

The Rolls Royce Merlin V12 conventional valve engine showed a max. of approx. 2500 hp from 27 litres.

Napier Sabre Cutaway:

http://www.khulsey.com/makoto_ouchi_napier_sabre.jpeg

The Sabre VII of 3055 hp, was on the point of going into production in Tempest VII's when WWII ended. The Tempests equipped with this engine were expected to achieve 500 mph.

http://www.hawkertempest.se/GreatestEngines.htm

DrHerb
11-12-2009, 06:38 PM
crank your speakers!

http://www.youtube.com/watch?v=kQZOc49ezX0

wolf-striked
11-14-2009, 10:28 PM
Originally posted by DrHerb:
crank your speakers!

http://www.youtube.com/watch?v=kQZOc49ezX0

Dam!!! I hope SOW sounds like that for the really high horsepower planes.I think even limiting how loud an engine can sound will give a sense of horspower in a sim.

JtD
11-14-2009, 11:55 PM
Great videos.

PanzerAce
11-15-2009, 02:58 AM
Sleeve valves are cool, but when it comes to sheer horsepower, it's hard to beat poppets (especially since unlike poppets, increasing power and cylinder pressures creates tons more drag on the sleeves)

RSS-Martin
11-15-2009, 02:59 AM
Sounds not bad, but still prefer the Maybach engine of this beast:
http://www.youtube.com/watch?v=vCsS20WJfBI

nsteense
11-17-2009, 04:09 AM
Originally posted by PanzerAce:
Sleeve valves are cool, but when it comes to sheer horsepower, it's hard to beat poppets (especially since unlike poppets, increasing power and cylinder pressures creates tons more drag on the sleeves)

The reason why they went with sleeves at that time was among others, that you can achieve a better volumetric efficiency which together with a short stroke on the Sabre, could obtain a higher RPM and therefor in theory can obtain higher Power (as this is in function of RPM anyway) without the need to enlarge the capacity of the engine. Which was the way the Americans went to obtain higher power ouput.
The comparison between the final versions of the Sabre VII (also sleeve valves) and the Pratt&Whitney R4360-25 Wasp Major can be made: 3500bhp at 37liter for the Sabre compared to 3050bhp@ 71liter for the Wasp. The obvious power to weight ratio is immediately clear.
The higher RPM was possible because there were no poppet valves restricting higher speeds; poppet valves have a tendency to float at higher speeds.
Technology of course have evolved these days, and the sleeve valves had its disadvantages, like the precise tolerances needed and the amount of friction (not drag) it creates, but your remark that for 'sheer horsepower, it's hard to beat poppets' is a bit one sided, because in the end Sabres and Centaurus engines were close to between 3000 and 5000bhp.

yuuppers
11-17-2009, 06:16 AM
Coolant flow was 357 gal/min and oil flow was 41 gal/min for the Sabre.

If the Sabre did not start after firing the 5 cartridges a lengthy maintenance procedure was required which include squirting oil into all 24 cylinders through the spark plug holes.

Kurfurst__
11-17-2009, 06:46 AM
Originally posted by nsteense:
The comparison between the final versions of the Sabre VII (also sleeve valves) and the Pratt&Whitney R4360-25 Wasp Major can be made: 3500bhp at 37liter for the Sabre compared to 3050bhp@ 71liter for the Wasp. The obvious power to weight ratio is immediately clear.

Comparisons based on displacement is quite meaningless - you need to know the dimensions and weight of the engines (as this is largely effects associated drag and overall efficiency), plus their auxiliary systems... this goes both radials vs inlines (ie. a radial does not have anz additional weight compared to an liquid cooled engine, which also requires the weight of coolant fluid and bulky radiators to be considered). Again, the displacements tell little about these things - the 44,5 liter DB 603 is supposed to be a monster by its displacement, actually its both lighter and smaller than for example the Sabre (and pretty much the same size if not smaller as the 35 liter Jumo 213, while the Sabre itself is some 50% heavier than the 35,7 liter DB 605... and much bigger of course. Fuel economy plays part too; after all, specification always include a given range requirements, and if you need to carry 20-30%-50% more fuel to achieve it would again add considerable weight.

So when comparing powers, its always important to know how heavy and bulky the whole 'package' as a whole is.

yuuppers
11-17-2009, 07:05 AM
Sabre VA
# Specific power: 1.36 hp/in³ (59.9 kW/L)
# Power-to-weight ratio: 1.29 hp/lb (2.06 kW/kg)

Merlin 61
# Specific power: 0.96 hp/in3 (43.6 kW/L)
# Power-to-weight ratio: 0.96 hp/lb (1.58 kW/kg) at maximum power.

DB603A
# Specific power: 0.59 hp/in³ (26.7 kW/L)
# Power-to-weight ratio: 0.79 hp/lb (1.29 kW/kg)

DB605AM
# Specific power: 0.77 hp/in³ (35.0 kW/L)
# Power-to-weight ratio: 1.02 hp/lb (1.68 kW/kg)

Low_Flyer_MkIX
11-17-2009, 07:25 AM
That's right Kurfy - a powerful Allied engine = more weight, therefore less speed and performance. A heavier Daimler = more power and general uberness. Simple logic, really. Irrefuteable.

DrHerb
11-17-2009, 07:56 AM
Out of curiosity, weren't Napier Sabres notorious maintainance hogs?

Kettenhunde
11-17-2009, 08:41 AM
So when comparing powers, its always important to know how heavy and bulky the whole 'package' as a whole is.

I think that is the point Kurfurst is making and not some comparison of allied or axis engines.

PanzerAce
11-17-2009, 10:41 AM
Originally posted by nsteense:

The reason why they went with sleeves at that time was among others, that you can achieve a better volumetric efficiency which together with a short stroke on the Sabre, could obtain a higher RPM and therefor in theory can obtain higher Power (as this is in function of RPM anyway) without the need to enlarge the capacity of the engine. Which was the way the Americans went to obtain higher power ouput.
The comparison between the final versions of the Sabre VII (also sleeve valves) and the Pratt&Whitney R4360-25 Wasp Major can be made: 3500bhp at 37liter for the Sabre compared to 3050bhp@ 71liter for the Wasp. The obvious power to weight ratio is immediately clear.
The higher RPM was possible because there were no poppet valves restricting higher speeds; poppet valves have a tendency to float at higher speeds.
Technology of course have evolved these days, and the sleeve valves had its disadvantages, like the precise tolerances needed and the amount of friction (not drag) it creates, but your remark that for 'sheer horsepower, it's hard to beat poppets' is a bit one sided, because in the end Sabres and Centaurus engines were close to between 3000 and 5000bhp.

I'm not saying that sleeve valves were bad, but (IMHO), they were a stop gap measure to address issues that the engine manufactures were still struggling with at the time. re the HP comment, how many sleeve valve engines fly in reno anyways? http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

"There's no replacement for displacement" also comes to mind...

DrHerb
11-17-2009, 11:10 AM
This thread needs some R-4360 lovin!

http://www.youtube.com/watch?v...RBBc&feature=related (http://www.youtube.com/watch?v=gkzDhaDRBBc&feature=related)

nsteense
11-17-2009, 02:20 PM
Originally posted by PanzerAce:


I'm not saying that sleeve valves were bad, but (IMHO), they were a stop gap measure to address issues that the engine manufactures were still struggling with at the time. re the HP comment, how many sleeve valve engines fly in reno anyways? http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

"There's no replacement for displacement" also comes to mind...

That's why I said 'at the time' http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif It's an idea that works, but not the easiest one. That is probably the way the Brits think: let's go and try something completely different then anybody else and make it work. Although Bristol apparently swore by it, by the looks of it considering the many designs with sleeve valves.
And yes that is why you probaly won't see any at Reno, because I guess that must be challenge to work on those engines (and next to that the amount of parts for those engines are probably a lot less well supplied compared to P&Ws) http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Kurfurst__
11-17-2009, 03:30 PM
Originally posted by Low_Flyer_MkIX:
That's right Kurfy - a powerful Allied engine = more weight, therefore less speed and performance.[/QUOTE]

British aero engines during Word War II tended to be like that, big power in bulky package = solving the problem with plenty of brute force but with little efficiency..

The Sabre weighted a bit over a TON, dry weight, without major accossories like radiators etc. It also had considerably larger frontal area than the typical liquid cooled inlines.

Its about the size and bulk of a typical radial engine. It has the same drawbacks (higher drag, bulk), with some drawbacks of a liquid cooled one. Its no particular wonder that the Sabre powered fighters were amongst the largest of WW2... its a big engine, with big power. As a piece of engineering, its a wonderful (24 cylinders, sleeve valves, ultra high rpm etc.), but as a practical solution, its less attractive, being bulky and troublesome, given the complexity. Though personally I like it much more than the R-R products... the Sabre was innovative, but it was a big package.


A heavier Daimler = more power and general uberness. Simple logic, really. Irrefuteable.

So which Daimler, complete with accessories (supercharger, fuel injector/carburator, radiators/intercooler, propeller etc) , was heavier than the Sabre, or for even, the a comparable timeframe Merlin or Griffon, also complete with aforementioned accessories...?

I am all ears. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

** whistles as LF Mk IX walks towards the minefield **

julian265
11-17-2009, 04:30 PM
If specific power is less useful without complete engine size and weight, then power vs the complete size and weight is less useful than considering the aircraft and engine as a complete package, realising that the engine does not account for it's entire weight.

Where are we going with this??

TheGrunch
11-17-2009, 05:03 PM
Originally posted by Kurfurst__:
So which Daimler, complete with accessories (supercharger, fuel injector/carburator, radiators/intercooler, propeller etc) , was heavier than the Sabre, or for even, the a comparable timeframe Merlin or Griffon, also complete with aforementioned accessories...?

I am all ears. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

** whistles as LF Mk IX walks towards the minefield **
Merlins/Griffons of a comparable timeframe might have been heavier, but they also developed more power. Swings and roundabouts. As for the Sabre, what Daimler was as powerful as the Sabre? Seems pretty pointless to focus purely on the weight, as well, to be honest.

Kurfurst__
11-17-2009, 05:14 PM
Agreed - the point being is that the aiframe manufacturer essentially looks to obtain the highest performance. Its the net total that needs to be considered.

To give a rude example, if engine A develops + 200 HP, but its associated fittings will increase drag by such that it will require additional 150 horsepower to overcome, the net gain in power is 50 HP. The same performance will be achieved by an engine B that develops only +100 HP, but its installation will add only 50 HP worth of drag.

Anyway, just one further point about the Sabre - for all practical purposes its like a radial engine.

Take a look at the dimensions:

Napier Sabre

Length: 82.25 in (2089 mm)
Width: 40 in (1016 mm)
Height: 46 in (1168 mm)
Dry weight: 2,360 lb (1,070 kg)

ie. frontal area being apprx. 1016 mm x 1168 mm = 1,186 sq. meters

in comparison BMW 801 radial:

Length: 2,006 mm (79 in)
Diameter: 1,290 mm (51 in)
Dry weight: 1,012 kg (2,226 lb)

ie. frontal area being apprx. 645 mm x 645 mm x 3.14 = 1,306 sq. meters

So while the Sabre is a tad smaller in frontal area, its probably considerably heavier than the radial BMW, considering the weight of coolant fluid and the radiator in which it circulates. The weight of the latter can be quite considerable, for example on the Spit IX w. the Merlin 61 (with much less output than the Sabre, and thus less cooling requirement), the coolant radiators weighted 88.5 kg, and the intercooler's radiator another 42.5 kg. The coolant tank weighted 10 kg, plus some additional weight for coolant fluid. I pretty sure the ones on the Typhoon/Tempest were larger compared to the Spit.

In short, direct comparisons between radials and liquid cooled engines in general is a bit misleading, since the latter also needs some rather bulky aux. systems to operate.

M_Gunz
11-17-2009, 09:04 PM
So that's how a sleeve valve works. Interesting. I remember reading how the new bikes out around 1960 (not Harleys)
used sleeve valves to get the revs up and IIRC 2-stroke engines at least on some if not all, Hondas and maybe Triumphs
but it's been a long time. Anyway the descriptions given didn't do it justice and it is interesting. You don't get
a lot of power till the revs kick up but boy when they do it's like a slingshot, you're throttling down just to keep
from running into traffic ahead. I don't see why there's a gas shortage when rice runs so fast!

Kettenhunde
11-17-2009, 09:31 PM
Seems pretty pointless to focus purely on the weight, as well, to be honest.

Power to weight is what is important to an aircraft designer.

yuuppers
11-17-2009, 09:33 PM
Originally posted by M_Gunz:
So that's how a sleeve valve works. Interesting. I remember reading how the new bikes out around 1960 (not Harleys)
used sleeve valves to get the revs up and IIRC 2-stroke engines at least on some if not all, Hondas and maybe Triumphs but it's been a long time. Anyway the descriptions given didn't do it justice and it is interesting. You don't get a lot of power till the revs kick up but boy when they do it's like a slingshot, you're throttling down just to keep from running into traffic ahead. I don't see why there's a gas shortage when rice runs so fast!

A sleeve valve consists of one or more machined sleeves. It fits between the piston and the cylinder wall in the cylinder of an internal combustion engine where it rotates and/or slides, ports (holes) in the side of the valve(s) aligning with the cylinder's inlet and exhaust ports at the appropriate stages in the engine's cycle.

The only similarity to a 2 stroke engine is the ports in the cylinder wall.

What were the names of these motorcycles using sleeve valve engines in the '60s?

There was rotary valve engines coming out in the '60s. Kawasaki and Bridgestone in the late '60s did for public use.

Hondas and Triumphs used poppet valve 4 stroke engines.

Nice racial slur. http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif http://forums.ubi.com/groupee_common/emoticons/icon_frown.gif

JtD
11-17-2009, 11:48 PM
Originally posted by julian265:
If specific power is less useful without complete engine size and weight, then power vs the complete size and weight is less useful than considering the aircraft and engine as a complete package, realising that the engine does not account for it's entire weight.

Where are we going with this??

Yes, I think that, too. What would say a P-47 be like if it mounted a smaller, lighter, less powerful and more efficient engine?

Was a plane as big as it was because the engine was as big as it was or was the engine as big as it was because the plane was as big as it was?

ImpStarDuece
11-18-2009, 12:29 AM
SNIP


Take a look at the dimensions:

Napier Sabre

Length: 82.25 in (2089 mm)
Width: 40 in (1016 mm)
Height: 46 in (1168 mm)
Dry weight: 2,360 lb (1,070 kg)

ie. frontal area being apprx. 1016 mm x 1168 mm = 1,186 sq. meters

in comparison BMW 801 radial:

Length: 2,006 mm (79 in)
Diameter: 1,290 mm (51 in)
Dry weight: 1,012 kg (2,226 lb)

ie. frontal area being apprx. 645 mm x 645 mm x 3.14 = 1,306 sq. meters

So while the Sabre is a tad smaller in frontal area, its probably considerably heavier than the radial BMW, considering the weight of coolant fluid and the radiator in which it circulates.

Frontal areas according to Paul H. Wilkinson’s series entitled “Aircraft Engines of the World”

Sabre Va: 8.8 sq ft
BMW 801D: 14.7 sq ft

Others:

Inlines

DB 601E: 5.4 sq ft
DB 603A: 7.0 sq ft
DB 605B: 6.9 sq ft
DB 605A: 5.5 sq ft

Ju213-A: 6.3 sq ft

Merlin X, XX, 45: 5.8 sq ft
Merlin 61, 63: 6.1 sq ft
Merlin 66, 100: 7.5 sq ft

Packard V1650-1: 5.8
V1650-3/7: 5.9 sq ft
V1650-9: 7.5 sq ft (I wonder what the Americans did different)

Griffon 65, 69: 7.9 sq ft

Allison V1710-C15: 6.2 sq ft
V1710-89, F17: 6.1 sq ft
V1710-131: 6.2 sq ft

Radials:

Bristol Centaurus 57: 16.6 sq ft
Bristol Perseus 100: 16.6 sq ft

P&W R1830: 12.6 sq ft
R2000-D: 13.4 sq ft
R2800-B: 15.0 sq ft

Wright R1820-G&H: 16.6
R2600 B Series: 16.0
R3350 B Series: 17.0

I also find several different dry weights for the 801: 1,012 kg, as on wiki for the 801C, as well as 1,228 kg and 1,342 kg for the 801D.

Anyone got anything official?

Gibbage1
11-18-2009, 12:56 AM
Originally posted by JtD:
Yes, I think that, too. What would say a P-47 be like if it mounted a smaller, lighter, less powerful and more efficient engine?


They did make a smaller P-47.

http://www.airwar.ru/image/idop/fww2/p35/p35-3.jpg

Only problem was the speed sucked, range sucked, firepower sucked.. It all sucked. The bigger engine allowed for more fuel, more speed, more firepower, and more bombs to be carried. Same for the F4F and F6F. Yes, not the same design, but the bigger F6F was more combat capable by far.

BillSwagger
11-18-2009, 01:29 AM
Originally posted by JtD:
Yes, I think that, too. What would say a P-47 be like if it mounted a smaller, lighter, less powerful and more efficient engine?

Was a plane as big as it was because the engine was as big as it was or was the engine as big as it was because the plane was as big as it was?

I know this is probably a rhetorical question, but if not, my answer would be that most planes from that era were designed to meet certain combat specifications imposed by the army/air force/navy.

I think if their had been no war, then racing would've taken aviation in a different direction. We'd see more P-77 type airplanes, with really light construction and powerful motors.
There would be no practical use for protecting the pilot or even having him positioned well to see over the nose in combat situation.
You could just build planes for speed and performance.

http://upload.wikimedia.org/wikipedia/en/1/13/Bell_XP-77.jpg



I think the technology was there, but you didn't want to fly a wooden airplane through a flak barrage, it had to serve some other purpose than just being able to go fast.

Low_Flyer_MkIX
11-18-2009, 01:43 AM
Originally posted by Kurfurst__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Low_Flyer_MkIX:
That's right Kurfy - a powerful Allied engine = more weight, therefore less speed and performance. </div></BLOCKQUOTE>

British aero engines during Word War II tended to be like that, big power in bulky package = solving the problem with plenty of brute force but with little efficiency..

The Sabre weighted a bit over a TON, dry weight, without major accossories like radiators etc. It also had considerably larger frontal area than the typical liquid cooled inlines.

Its about the size and bulk of a typical radial engine. It has the same drawbacks (higher drag, bulk), with some drawbacks of a liquid cooled one. Its no particular wonder that the Sabre powered fighters were amongst the largest of WW2... its a big engine, with big power. As a piece of engineering, its a wonderful (24 cylinders, sleeve valves, ultra high rpm etc.), but as a practical solution, its less attractive, being bulky and troublesome, given the complexity. Though personally I like it much more than the R-R products... the Sabre was innovative, but it was a big package.


A heavier Daimler = more power and general uberness. Simple logic, really. Irrefuteable.

So which Daimler, complete with accessories (supercharger, fuel injector/carburator, radiators/intercooler, propeller etc) , was heavier than the Sabre, or for even, the a comparable timeframe Merlin or Griffon, also complete with aforementioned accessories...?

I am all ears. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

** whistles as LF Mk IX walks towards the minefield **[/QUOTE]

So just what did LF mean by 'heavier'? Let's see...maybe he meant heavier by progression relative to the aircraft in question? Or to the national strategy of the aero industry in question? Just a thought - what would I know about the way his mind works? Don't let me stand in the way of your agenda.

Perhaps the statement was sentence specific? I note with interest that you realised this in your retort, and broke up the structure accordinly.

You could, if you were so inclined, take the second equation to purport 'Heavier than the Daimlers that had gone before it' perhaps? Or was Messerteknik so uber that engine weight went down as the series progressed? It's a possibility - what with German genius for overcoming raw material shortages. I'm all ears.

'Vorsprung durch strohmensch' as they say in Augsburg.

================================================== ===============

Interesting post about air racers, Mr Swagger. Thought-provoking stuff.

BillSwagger
11-18-2009, 01:47 AM
http://home.att.net/~Historyzone/P-44.jpg
P-44,
the evolutionary link between the Lancer and Thunderbolt, but never saw production.
This is what i'd consider the smaller P-47, if you don't include the XP-47A which was also a dwarfed version of the plane, but much closer to the P-47C and D production sizes.

M_Gunz
11-18-2009, 03:51 AM
Much of the size of the P-47 is there to accommodate the turbocharger and intercooler piping. When you add weight
and size for that you also need more fuel and oil and heavier gear, which requires yet more fuel. Throw on a couple-
four extra 50 cals and what more you need? Stronger structure plus still more fuel.

PanzerAce
11-19-2009, 11:49 PM
Originally posted by nsteense:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PanzerAce:


I'm not saying that sleeve valves were bad, but (IMHO), they were a stop gap measure to address issues that the engine manufactures were still struggling with at the time. re the HP comment, how many sleeve valve engines fly in reno anyways? http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

"There's no replacement for displacement" also comes to mind...

That's why I said 'at the time' http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif It's an idea that works, but not the easiest one. That is probably the way the Brits think: let's go and try something completely different then anybody else and make it work. Although Bristol apparently swore by it, by the looks of it considering the many designs with sleeve valves.
And yes that is why you probaly won't see any at Reno, because I guess that must be challenge to work on those engines (and next to that the amount of parts for those engines are probably a lot less well supplied compared to P&Ws) http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif </div></BLOCKQUOTE>

Well, another reason that I just thought of for no sleeve valves at reno is that they would take *alot* of machining to get the volumetric efficiencies right, since they would need new sleeves for any changes in timing/duration/etc. However, with poppets, all you have to change is a camshaft or two, and you've got a whole new power curve.

nsteense
11-20-2009, 01:48 AM
Originally posted by PanzerAce:

Well, another reason that I just thought of for no sleeve valves at reno is that they would take *alot* of machining to get the volumetric efficiencies right, since they would need new sleeves for any changes in timing/duration/etc. However, with poppets, all you have to change is a camshaft or two, and you've got a whole new power curve.

You see, sleeve valves have their disadvantages!! http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Although, thinking about it has made me curious: How do they change change the camshaft on a radial, knowing it is actually a ring?