Engine hp

Taft Racing

Member
Given I've never seen any real dyno sheets and based off a 131 Sudam being rated at 50, I'd say a real number for the Sudam would be 40-43 and the stock 250 with out trany at a real 55-58, same for a stock 450, torque would be higher on the 450. The Jawa being 500cc my guess would be a real 60=63 HP The Wankle stock 40 ish. Brc dyno sheet have been listed 45-50. I've heard of all kinds of bragging and big numbers but those guys never actually produce any data so I'm calling bs on those numbers.

Steve you've done dyno runs with yours but why have you never given any actually data? Are you just stirring the pot a little? These kinds of posts don't really do any thing except ask for trouble. It would be nice if facts were layed out so racers could study proven documented facts. Youll notice threads on the 2 cycle section where the guys engage in reality, science, engineering, and most of all sharing of knowledge.
 

JawaMaster09

New member
I have all my Dyno sheets but I'm not going to show them on bob's.....remember it's not all about the highest number its about the curve....Tim you are not that far off your guess at the Jawa's power with a (carburator not fuel injection) at the crank as long as it is a long stroke the newer jawa's are alot more powerful, somebody is going to have alot of fun with the new one I built and never raced it is stronger than anything the UAS has seen raced to date.
 

Sjg22

Member
Given I've never seen any real dyno sheets and based off a 131 Sudam being rated at 50, I'd say a real number for the Sudam would be 40-43 and the stock 250 with out trany at a real 55-58, same for a stock 450, torque would be higher on the 450. The Jawa being 500cc my guess would be a real 60=63 HP The Wankle stock 40 ish. Brc dyno sheet have been listed 45-50. I've heard of all kinds of bragging and big numbers but those guys never actually produce any data so I'm calling bs on those numbers.

Steve you've done dyno runs with yours but why have you never given any actually data? Are you just stirring the pot a little? These kinds of posts don't really do any thing except ask for trouble. It would be nice if facts were layed out so racers could study proven documented facts. Youll notice threads on the 2 cycle section where the guys engage in reality, science, engineering, and most of all sharing of knowledge.

Tim I just thought is was a fun subject
 

MikeGrady

Member
HP is a mathematical computation anyway. Torque is a physical measure of work. How much work the engine can do over it's complete usable band width is what matters.

HP was made up by a guy named James Watt. When his measurements didn't add to to his expectations, he multiplied in a fudge factor. It is astonishing that we still use it.

Of all the engines the UAS allows, I would guess that the Jawa is the bad boy of the bunch.
Mike
 

Wes Snow

New member
I may not have my facts straight, but is a jawa not a 2 valve and the 450's are four or five, and both are overhead cam. Why would a 450 not have more power potential than a jawa if both are running the same fuel and have the same amount of cubic inch? It is easy to buy a big bore kit and stoker crank kit for the 450's but it seems like everyone's opinion is that the jawa is a superior engine to start with. What am I missing? Does the jawa weigh less?
 

JawaMaster09

New member
I may not have my facts straight, but is a jawa not a 2 valve and the 450's are four or five, and both are overhead cam. Why would a 450 not have more power potential than a jawa if both are running the same fuel and have the same amount of cubic inch? It is easy to buy a big bore kit and stoker crank kit for the 450's but it seems like everyone's opinion is that the jawa is a superior engine to start with. What am I missing? Does the jawa weigh less?

The Jawa is IMO the best oval track engine... the 450's with the short stroke are not as good for oval racing but better for jumping ramps they run ok on an oval, but the large stroke and long rod help make the torque smoothness of the Jawa is superior to the other 450cc 4 strokes. The 5 valve heads are not as good as the Jawa as well... The Jawa weighs more than the 450's do.
 
HP means diddly if you can't get it hooked up! Some can and some can't.

I have never had any of my engines on a dyno. Not saying that I never would but, it only matters when you are on the track.

Brian #89
 
What are cam specs on a jawa? Compaired to the tiny cams in a stock 450. A 450 with 230ish* @.050" will make power to 10k with no problem, them 4 and 5 valves work. There cams need to be tailored to racing rpm to see big power on the oval.
Not saying one is better than the other, I don't have any knowledge with a jawa, but willing to learn.
 

Taft Racing

Member
Jerry you bring up some interesting thoughts. On the 250 2 stroke the shorter stroke engines have the ability to turn more rpms and should be a smoother torque curve than the longer stroke engine. Those do to the longer stroke need to get the job done on a shorter rpm range do to piston velocity.

On the 450's the shorter stroke allows them to turn higher rpm also, on a Bike they tend to short shift the big bores and let the torque do the work. On a Kart we may be able to use the higher rpm range, On the Jawa it's been refined for speedway racing for years, I think thats why it has the right stuff right out of the box for karting. I don't believe we have use for or can use what were now tapping into HP wise.

Steve I question your thread because you make a turn key 250, you know dyno numbers for the BRC and your PK 250 and yet you start a thread asking a question you already know the answer too. I know you work in a industry filled with secrets and holding what you know close to the vest is business as usual. In what were doing does that really give you a advantage? seams to me it would be a great selling tool to expose real dyno info for the masses to see and compare what these things are capable of.

I'm hoping to have a Jawa to dig into here soon. I intend to steal info left and right and incorporate that knowledge into my 450 cases. I know once I have a dyno in house I'll plaster the info all over the internet.
 
Several bike and quad guys I have talked to have said any numbers posted for bikes or quads is at the rear wheel. I looked up the specs and the Jawa is a 4 valve engine. Cam timing is also listed. www.codyracing.com

Description of JAWA Engine Type 884 and 888

Single cylinder, single OHC with a swept volume of 500 ccm. Air-cooled, four valve with a bore of 85 mm and a stroke of 87 mm, or a bore of 88 mm and stroke of 81.2 mm. Engine oil sumps, head and cylinders are made from aluminum alloy. The big-end and main bearings are of caged needle-roller type. The camshaft is seated inside the head on needle bearings and is chain driven. Valves are at a 35 angle with one tapered helical spring per valve. Valve seats are hot pressed into the head. The forged piston is made of light alloy with two piston rings. The engine has a circulation lubrication system. The oil tank is situated in the valve gear cover and right hand crank case. The engine holds .6 litre of oil. The oil can be checked at the oil level gauge. A 34 mm carburetor is used with electronic ignition.

Technical Data


Model 884 bore / stroke 85 mm / 87 mm
Model 888 bore / stroke 88 mm / 81.2mm
Swept volume 493 ccm
Maximum power / RPM 63-70 bhp / 8500-10500 RPM
Compression ratio 13-15:1
Carburetor Dellorto 34 mm
Ignition advance 30 -33
Ignition PVL Electronic
Spark plug Champion G55R / G57R
Valve / cam timing 10A 13A 17A 01 02 03
Ex. valve open / close 69 /31 69 /31 67 /30 62 /30 66 /33 62/30
In, valve open / close 37 /67 34 /67 39 /62 31 /68 39 /62 37/68
(measured at a valve lift of 1 mm)
Valve clearance Int / ex .004" / .006"
Fuel Methanol
Oil (.6 litre) Silkolene Castorene R-50
 
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