98.5 HP Commando motor after 97 races

This extraordinary 98.5 HP 920cc Commando motor on Alk has just completed 97 races using the same pistons/rings and showing no discernible piston/bore wear. If such a fine motor with high grade components can survive this kind of high stress abuse – imagine how long it would last in street tune.
Details below.

Robert Hood and passenger Mark Thompson won the New Zealand Classic Motorcycle Racing Register (NZMCRR) Post Classic Sidecar Championship in 2013, 2014 and 2015. short forged 920cc pistons and longer rods. Maney cases and Barrels. One piece crank by Graham Martin in NZ. 36 mm Dellorto’s. 2mm oversize inlets. 11.5:1 compression on methanol. 98.5 BHP at the back wheel.



Roberts 2nd Email

Went to flat top pistons after doing a drive side mains. Had 14. something:1 compression [with domed pistons]. Gained 6HP with the flat top pistons.
The flat tops and new rings went in mid 2013. I have no record of any ring replacement since then.
We did 17 races in 2013 on the new motor, 38 in 2014, 25 in 2015 and we’ve done 17 this year so far. Plus practices and test days. Our Club races are 4 or 5 laps.
We had the head off a few times over last Christmas and noticed no discernible piston wear. Our cylinder PSI cold after a head recon then was around 220 per side.

Cheers
Robert.

Cool outfit. I notice he also likes the long intakes. It's a shame they are so hard to fit into a Commando frame.

Ken

lcrken said:

Cool outfit. I notice he also likes the long intakes. It's a shame they are so hard to fit into a Commando frame.

Ken

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Yes - he's getting the long manifold ram effect. They look like they're made of steel and tapered. Not enough Norton motors have that benefit because of space restrictions. But you can do it with a low oil tank and some frame mods - not easy with a Commando frame but not so bad with race frames or featherbeds.

Concerning longevity - I asked Robert what oil he used - his answer below.

Currently using Fuchs Racing 60. Was using Valvoline Racing 50 previously. Probably going to move onto a Morris oil in September.
I have an external oil filter and a thermostat to the T160 oil cooler. I change the oil every three meetings at least.
When we changed to flat pistons I had the barrels lightly honed then. Just talked to Mark and he confirms that we haven’t replaced the rings we put in in 2013.

Some racers I know use multi viscosity synthetic and end up with less protection. Brooking 850 uses 60wt I think. You also need to have the zinc additive.

So apart from the cylinder head, there are no Norton parts in the engine :lol:

gripper said:

So apart from the cylinder head, there are no Norton parts in the engine :lol:

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Apart from timing cover, cam timing gear, oil pump - probably not. What Norton with stock parts could survive 98 HP for 97 races? - Probably none. Stock aluminum rods wouldn't make it. Cast pistons would have sloppy ring lands and broken rings long before. Sidecars put extra stress on the motor with all that weight to pull around and its hard to keep them together. As for two wheelers - what Norton with stock parts can stay together in today's top class competition? - few if any. Its tougher these days. The bar has been raised. We should be grateful that there is a Norton in the winners circle - whatever parts are being used. I raced in the 1980s and had to modify/strengthen my cases and crank and even then they cracked. Racers today don't have a choice (if they want to win). As Herb Becker told me "what you can afford is always a problem - at all levels of racing".

When racing a commando 'what you can afford' primarily affects reliability. You cannot expect a near standard commando motor to last if you rev it regularly over 6,500 RPM. So if you have limited funds, the answer is to not go top end seeking more horsepower, but work on the midrange to make the motor deliver more torque. Then set the handling of the bike up so you can use the improved torque characteristic I suggest the 6 speed CR TTI gearbox is a better investment than thicker crankcases. However I tend to stay away from 'power circuits', especially if the other bikes in the race class have four cylinders. Better to out-ride the others in the corners and get a run on them, than join them in a 'point and squirt' drag race off the ripple strip. I once asked on this forum if anyone has ever hi-sided a commando - normally it doesn't seem to happen. So if you are tight in the corners, it is pretty safe to get hard on the gas really early.

gripper said:

So apart from the cylinder head, there are no Norton parts in the engine :lol:

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Let's not forget the rocker arms, rocker arm shafts, main bearings, banjo and banjo bolts for the rocker oil feed lines, timing gears, cam chain and various engine seals.

acotrel said:

I once asked on this forum if anyone has ever hi-sided a commando - normally it doesn't seem to happen. So if you are tight in the corners, it is pretty safe to get hard on the gas really early.

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I don't recall if I answered that question in your earlier post, but for the sake of historical accuracy, the answer is yes, at the exit of turn one at Daytona somewhere around 1990. My friend Mark was riding his Commando and had a nasty high side crash that put him in the local hospital with injuries that included a broken pelvis. That was the end of his road racing activities. But I do agree with you that it isn't something that you normally have to worry about with a Commando. HIs bike is the silver and black one in this picture of our bikes at Daytona in 1990.



Ken

Normalizing this down to 750 cc for displacement alone, this works out to:

(748/920) X 98.5 HP = 80.1 HP

This would be impressive if it were gas but this 920 runs on Methanol so I would expect much more or...........it is just a conservative build which is fine since there is much to be said about reliability and low maintenance. Even the compression ratio cited is rather low for Methanol

Looking at the difference in the product of mass flow rates and BTU/mass (or BTU flow rate) between gasoline and methanol we are talking about methanol delivering on the order of 60% more energy (or power). I will leave to everyone's imagination as to what evil one could do with that to a Norton Engine designed to take advantage of the additional energy (ex upwards of 16:1 compression ratio)

I have always used methanol when racing. My 850 is on standard compression, however the carbs are jetted as lean as they can safely be, and I run an additional 4 degrees ignition advance. The engine loves it - I've never had it on a dyno but it feels like 80 BHP - purely subjective. I think the difference between using methanol or petrol is probably about 10% in horsepower terms. However the major advantage is that it hides up your tuning errors. We used methanol extensively in Australia during the 50s. When our guys raced in the UK, they found the Poms could get their manxes going as fast on petrol as we could in Australia on methanol.

Say an 828cc Commando is a nominal 49 HP

49 X 166% for methanol = 81.34 HP

Alan, say again how much power do you think it feels like? :lol:

Naturally you are not making that power because you are missing the advantage that Methanol allows, that is high compression which equates to higher thermal efficiency plus the superior advantage of a compact and efficient combustion chamber resulting from the higher compression. There is also the cooling effect that Methanol has on the intake charge, thus a greater charge density. To go there on a regular basis you will likely need beefier stuff for an engine, something like a Nourish Race Engine.

gripper said:

So apart from the cylinder head, there are no Norton parts in the engine :lol:

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Let me just say......who cares :shock: what the heck you know (and I see your light hearted tongue in cheek gripper), but I've said it before, I think it is great that we can still get this "trick"stuff for our old ass bikes relatively easy, beefy cases, crank shafts, redesigned pistons and rods, modern coatings like ceramics and DLC, if the basic design couldn't be made to perform then none of this kind of stuff would even be out there, sure maybe some one offs, but probably no vendors like we have now. Anyway just my 2¢. :wink:

I have used methanol in Triumph motors on comp. ratios as low as 7 to 1 and still got a boost. The main thing the fuel does is increase the amount you use because the latent heat of vaporisation takes heat out of the carb and the incoming charge and increases it's density - the effect is a bit like supercharging. The more methanol you vaporise, the colder the air and the more methanol you need to get the mixture right and so on. However the effect is not linear. The best fuel ever except for nitro, was BP JA which was 65% methanol, 30% benzene and 10% acetone. However methanol itself also has only about two thirds the calorific value of petrol. So on 12 to 1 comp. you approximately double the amount of fuel you use however only get 1.5 times the energy and not all of it goes down the conrods. At 9 to 1 comp, the main jet size in an 850 commando is 670, not 1400 as it is when using 12 to 1 comp, so how much is wasted at 12 to 1 comp ? At lower comps you obviously don't get the horsepower boost however the motor still becomes more brisk. The other thing is that at lower comps the ignition timing you use is usually much more advanced over standard, when using methanol. So the effect on torque is probably different.
What I have found with my motor is that I have raised the overall gearing about twice and the acceleration out of corners increased, however that made first gear too high for the clutch starts where you have to heave the weight of the bike from a stand-still. With the 4 speed CR box the bike was superb everywhere else except off the start-line.
One of the main benefits of using methanol is that the motor runs much cooler overall. The iron barrels of the normal commando are not a bad thing.
If I was racing the low comp. commando seriously I'd use a methanol, toluene, acetone blend. You don't need much methanol present to get a substantial supercharging effect. The problem then would be handling the solvents safely while blending.
Do you guys have fuel checks at your race meetings ?

Back in about 1973 one of our better riders - Ken Blake was riding the Jesser Triumph which had a 730cc motor dosed up with a heap of nitro in the methanol. It handled superbly and with that fuel beat a lot of very good Manx Nortons. My friend was behind Ken in a race when the Triumph motor spread itself everywhere at Mallala Raceway and brought about 4 other riders down. He stormed up to Ken in the pits and yelled 'see what happens when you use that shit' ?
The only experience I've had with nitro has been using it in a speedway outfit. The owner felt no difference until the methanol/nitro mix got up around 60%. However I suspect that if you don't raise the gearing on the dirt, you don't feel the extra urge - nitro increases torque. And 'torque wins races'.

Interesting stuff Alan from first hand experience.

acotrel said:

The main thing the fuel does is increase the amount you use because the latent heat of vaporisation takes heat out of the carb and the incoming charge and increases it's density - the effect is a bit like supercharging.

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Opinions vary on what "the main thing" is but it may be a function of what compression ratio one is using.

acotrel said:

So on 12 to 1 comp. you approximately double the amount of fuel you use however only get 1.5 times the energy and not all of it goes down the conrods. At 9 to 1 comp, the main jet size in an 850 commando is 670, not 1400 as it is when using 12 to 1 comp, so how much is wasted at 12 to 1 comp ?

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Not sure what you are comparing the 12:1 compression ratio to. Can you explain why the dramatic increase in the engines ability to handle additional fuel just by increasing the compression ratio?

acotrel said:

The other thing is that at lower comps the ignition timing you use is usually much more advanced over standard, when using methanol. So the effect on torque is probably different.

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If I understand you correctly, to me, this is a bad thing and may very likely reflect a lazy combustion chamber.

acotrel said:

Do you guys have fuel checks at your race meetings ?

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I can only speak of here in the states where most if not all closed circuit (except drag bike and land speed record) racing does not allow for Methanol.

When you are tuning a motor for methanol, it is as difficult or easy as it is for petrol except that because your jets are much larger, minor changes have less effect. In the end the combustion chamber conditions you are seeking is very slightly prior to detonation right across the rev range. What happens in the combustion chamber is affected by three things - ignition advance, inlet charge mixture and comp. ratio. As you raise the comp ratio it is normal practice to use less ignition advance, and jet the carbs to suit that combination. At 9 to 1 comp. I use about 34 degrees ignition advance. at 12 to 1 it is normal to use the same advance as for petrol and at 14 to 1 it is normal to retard the ignition advance. What you find is that at 9 to 1 comp. ratio the jets are overall much smaller to get best performance. The jetting I mentioned previously for the 12 to 1 situation would be typical of what our historic guys use in 500cc singles. Most of them always jet rich and don't really know how to read a spark plug. When you use methanol, it is as important to lean off as much as possible without causing damage, as it is with petrol. I usually run slightly rich on the mains and forget about them, however how the needle and needle jet are set up is critical. My needle jet is now at 0.116 inch using Mikuni 6D petrol needles in my MK2 Amals. If I fit 0.117inch needle jets the bike is slightly sluggish coming out of corners. In a 12 to 1 comp motor the normal needle jet is 0.120 inch and the needles have dramatic tapers.
My brother does this stuff with Kawasaki 3 cylinder two strokes, if you get it even slightly wrong you get the big bill. One thing he never does is increase the comp. ratio - it is just asking for trouble. Most four strokes are nowhere near as critical. We have one Jawa speedway motor on 17 to 1 comp.

750 cc H2 Kawasaki two stroke on methanol :

https://www.youtube.com/watch?v=HYnXEQ0Aw1I

Dances with Shrapnel said:

Normalizing this down to 750 cc for displacement alone, this works out to:

(748/920) X 98.5 HP = 80.1 HP

This would be impressive if it were gas but this 920 runs on Methanol so I would expect much more or...........it is just a conservative build which is fine since there is much to be said about reliability and low maintenance. Even the compression ratio cited is rather low for Methanol

Looking at the difference in the product of mass flow rates and BTU/mass (or BTU flow rate) between gasoline and methanol we are talking about methanol delivering on the order of 60% more energy (or power). I will leave to everyone's imagination as to what evil one could do with that to a Norton Engine designed to take advantage of the additional energy (ex upwards of 16:1 compression ratio)

Click to expand...

Either I don’t understand the new math, or the suggestion that alcohol vs gasoline results in a power increase on the order of 60% is incorrect. Over the years the general information I’ve come across on the energy potential of various fuels in naturally aspirated engines is that alcohol (methanol) provides HP increase on the order of 10% (+ ?) and that nitro has the potential to about double the HP achieved with gasoline.

When looking up the energy content of gas and alcohol the specific values encountered vary (depending on how they were measured, who measured them and the gasoline composition), but the general relationship of gas having about 2X the energy content of alcohol remains quite consistent. Taking into account that the alcohol/air mixture strength employed in an engine is slightly more than ~ 2X the mixture strength of gasoline, overall, alcohol provides an increased energy content compared to gasoline.

The table below was created to illustrate the above points, i.e., that although gasoline possesses nearly twice the energy content of alcohol, when A/F ratios commonly used with each of these fuels are employed, alcohol has the potential to provide an energy increase on the order of 10%. Energy content of gas and methanol shown in the table were assigned based on values commonly found in the literature. In the example shown alcohol provides an energy benefit on the order of 11% (1583/1423 = 1.11). Alcohol can be employed at A/F ratios stronger than 6/1 so greater benefits than those illustrated here are possible.

You are correct. It is not 166%. The error on my part was assuming the statement made elsewhere in this thread - "However methanol itself also has only about two thirds the calorific value of petrol" was correct. Instead of Methanol being 66.67% the energy content of gasoline on a mass basis, it is more like 42.45% the energy content of gasoline on a mass basis. You know what they say about assuming.

For strict comparison, the analysis should be on a stoichiometric basis in order to compare apples to apples. Another comparison should be done on best power air/fuel ratios.

Stoichiometric value for gasoline is about 14.7:1 and varies a bit based on gasoline formulation. Best power ranges I have seen listed 12.5:1 to 12.8:1 and maybe richer for air cooled.

Stoichiometric for Methanol I see at 6.42:1 with references indicating going down to as low as 4:1
http://www.hotrod.com/news/1503-power-in-methanol-racing-alternative-fuel/
This is quite a span (6 - 6.42 down to 4) yet it is in line with what Alan has been saying and will dramatically impact power.

Best power air/fuel ratios will vary significantly for both fuels depending upon engine configuration (ex. air cooled versus water cooled)

I've seen the 60% figure before, attributed to Hot Rod Magazine experts. It was based on assuming you were using about a 4:1 air-fuel ratio for methanol and 12.5 for gasoline. That means you are burning more than three times more methanol than gasoline, so even with the lower BTU/kg rating of methanol, you still had a large increase in total energy. I think that's a mistake. In reality, at 4:1 fuel air ratio you are not efficiently burning all the fuel. Methanol is really tolerant of rich mixtures, so it still works at 4:1, but it doesn't produce more power than at mixtures closer to 6:1. If you compare the two fuels either at their stoichiometric ratios, 14.6 for gas and 6.45 for methanol, or at more real world values of 12.5 for gasoline and 6 for methanol, you get only a little over 2 times as much fuel. That's where the 10% sort of numbers for power gain that we are used to seeing come from. If you do the calcs from the stoichiometric ratios, you get a power gain of 5-6%. You can add to that some gains from the cooling effect of methanol giving you a denser intake charge, but it's still hard to see a gain higher than 10% without increasing the compression ratio.

According to my favorite "fuels for dummies" book, "High-Performance Automotive Fuels and Fluids", by Jeff Hartman, switching from gasoline to methanol in the same engine typically adds 8-12% to mid-range torque in un-optimized engines. The big deal with methanol is that it's cooling and anti-knock properties allow for very high compression ratios. If you optimize the engine by raising the compression ratio to 16:1 or more, you pick up some more horsepower from higher combustion efficiency, but still nothing like 60%. And it's really hard to raise the CR in a Commando engine that high. You might get another 10% efficiency, depending on how high you can get the CR, but that's about it. Raising the CR from 10:1 to 14:1 gives a theoretical increase in power of about 9%. Overall, it's hard to see how you could get more than maybe 10-15% more horsepower from a Commando engine by running on methanol, and that's with everything optimized (high CR, more ignition advance, and carbs modified for more flow). The real gains in horsepower come when you start "tipping the can" by adding nitromethane to methanol, but that is very hard on an engine, and I don't think our Commandos would live very long on a high nitro diet. OK for a drag bike or land speed bike, maybe. I had a friend who ran a Commando 920 drag bike on methanol/nitro for a while. It was pretty impressive. And Dennis Manning managed some pretty good times on the salt with his streamliner with twin 850 Commando engines running on methanol and nitro. Some of the Triumph guys at Bonneville back in the day were running as high as 80-90% nitro. They broke a lot of engines in the process, but also set some pretty good records.

When I first bought the monoshock Norton from Jim Schmidt, it was set up for a methanol/gasoline blend with Jim's home made flat slide carbs. I didn't have time to change over to carbs to run just gasoline, so I ran it that way in an AMA national at Sears Point, and it worked really well. It was illegal, but nobody cared because the bike wasn't up at the front with the big names. I think the cooling effect of the methanol was really good for the Norton. I later fitted carbs and ran straight gasoline. I never noticed much difference in performance between the two fuels. Relying on an admittedly poor memory, I think the blend was around 1/3 methanol and 2/3 race gas.

It's when you go to supercharged engines (turbo, positive displacement, etc.) that you can really rack up some horsepower gains with methanol. It's cooling properties and high anit-detonation ratings let you run higher boost pressures than with gasoline, with the resultant higher horsepower figures. I think you might really find cases of 60% more horsepower there.

Just my humble opinion.

Ken