4 Valves instead of 2 gives 100% more power?

[Sasa]

Well... @Dool since you brought me into this "querelle", I shall give my opinion too...

First of all I wanted to establish some baseline, so a simple search for "Continental GT 535 dyno charts" was needed to have a common ground of discussion...

here is an interesting link:

Royal Enfield Continental GT 535 : Ownership Review (29,000 km and 7 years)

Royal Enfield Continental GT 535 : Ownership Review (29,000 km and 7 years)

www.team-bhp.com

Dyno chart apparently from Powertronic, stock bike dynoed at 18.1hp...

Then I stumbled upon this other fella, who machined a new head for the 535 from a billet of aluminum and he dynoed the bike with the stock head and his head.

ELABORARE per bene GT continental (Pagina 2) / UCE mono EFI (Bullet 500 / Continental GT 535) / The Royals Forum

Forum The Royals.it Forum utenti e appassionati Royal Enfield

forum.theroyals.it

Don't be fooled too much, the stock bike clocked at 25hp, but that was already with PC, free flowing filter and exhaust. I'd assume the completely stock bike would have clocked at 22/22,5hp. There is an interesting take though: designing the head cleverly he gained 5hp. Head alone.

Another interesting link:

ROYAL ENFIELD 500 and 535 (Exclusive) | Rapid Bike Australia

Rapid Bike for Royal Enfield in tuning module. The EVO unit will manage the fuel injection and self tune on the 535 and 500 models.

rapidbike.com.au

This is from DIMSPORT, a very reputable italian outfit that makes add on ECU and is in racing business since 25yrs.
The purple line is stock, again 23hp.

Now if we mean all results you get around 21/21.5hp. These are three independent sources . I could doubt one, not all three of them.

There is another interesting fact: we dynoed a bike with bv head and ported conduit, but without a proper cam, optimized for high RPMs like the Kent, the full potential of that ported head wasn't exploited. The cam alone provided up 4hp, all other things being equal, makes you wonder what a 4 valve head could do...

Now this is a baseline, you might agree or not, but this are facts, not opinions.

Let's discuss now the HMC kit: that's a fully fledged kit with new 4 valve head and cams and presumably the head is properly ported, shifting the powerband toward the high RPM. Also valves might be way bigger than stock, we don't know. Do I think that it could provide up to 16hp over the 20hp stock? Yes I do. We know nothing about the fluid-dynamic study behind that head, so assuming they are lying is just a baseless opinion.
Moreover I would be surprised if TORQUE was doubled but that is not the case. Rather power was increased, but comparing power at two different RPMs values has not much meaning.
For a nice reading on power and torque give this link a go:

Power and Torque Explained — Math for Motorcycles

All about power (horsepower) and torque in motorcycles, and how they relate to top speed and thrust.

motofomo.com

Final thought: that is a complete package, that has been likely deeply optimized, so such a gain is more than achievable. The same @Dool has already shown a similar power output (32.6rwhp) for a smaller capacity bike (443 vs 500) so yes, that power level is more than achievable by a 500cc. Moreover 4 valves have always been used to make engine breath better and rev higher, and with higher rev comes higher power (not torque, read the link above). It isn't by chance that all sporty engines are 4 valves per cylinder, even 5 or 6 in some exotics solutions (Alfa romeo comes to mind). Two valves have always been related to slower revving but torquey engines.

Side note to all the well calibrated dyno butts out there: unless your butt knows math, you'll only be able to judge torque, because that is what propels you forward. And that is even more noticeable the more it's down low in the RPM range, since you'll feel a strong push forward when you're going at low speed. So whenever your butt judges a bike powerful, you'd rather use the expression "torquey", unless again your butt knows how to multiply...

I hope this shades some light on the topic. Peace.

 

[Sasa]

Well having owned both, I suppose that makes me the Expert But on the Himalayan not a Tractor!
25% as o 535 that was Dynoed does under represent with HP as claims of 29 (at the crank ) are easy to find.
As I would only present valid data I actually expect that the others do the same so perhaps I did not give enough scrutiny to their Graph which appears to show that 4 is worse than 2 Valves between about 3100 and 3600rpm where some folk ride, but I think it is a fair trade off To be Fair the Bigger Valves we played with were just that, bigger valves and showed little or no improvement on the Dyno.

Where are the disgruntled 535 owners? I have not seen any graphs showing RWHP exceeding 19.81 so maybe they are gutless.

The other take from that chart is that it all happens after, like after the red line sort of thing, my bike does 8000 and I think @Sasa wont give it enough fuel to go to 9000, thats where the power is apparently.

I worked out long ago that I couldn't sit on a Conti as much as I admire the looks, just as I could not sit on the Inter when it came out ( was released! ) so I bought the one I could sit on.

Turns out it was, as in used to be in my case, a gutless but easy to sit on Motorcycle, it is not now as evidenced by my honest Dyno charts
There was a German bloke his name started with G and spell check isnt helping! but he is remembered as saying something about a Big lie not being disputed as easily as a small one, perhaps a what with all the investment into this endeavor they have been tempted.
E&OEA

@Dool yes, I won't give it enough fuel to go to 9000RPMs, I cheerish you bikes and I don't want them to blow up like a firecracker!

 

[sam2019]

25% as opposed to 100 from memory so the PC wins hands down and is "industry standard"

is this cryptic sentence saying the PC can add 100% more fuel?

The Sick? 535 that was Dynoed does under represent with HP as claims of 29 (at the crank ) are easy to find.

is this an English sentence? who are you trying to say? sick?? you mean defective? 29 at cranck are about 26 RWHP which is what I use as value while Hitch uses 19.8. 19.8 is guaranteed wrong. No just a little bit wrong but VERY wrong. If its was right than a STOCK Hima would be having more power than the 535 which CLEARLY is not the case. In fact even a 500 Bullet has more power than a STOCK Hima.

As I would only present valid data I actually expect that the others do the same so perhaps I did not give enough scrutiny to their Graph

apparently you did not. instead you called me an idiot in not so many words. thank you for that.
You also start to seemingly believe that Hitch must be HONEST in their advertising. Maybe they are the exception in the worlds of commerce, maybe not.

Where are the disgruntled 535 owners? I have not seen any graphs showing RWHP exceeding 19.81 so maybe they are gutless.

what do you mean to say here? it would really help if you where less cryptic and more clear in what you say. which disgruntled 535 owners? why would any of them dyno their bike? for them, that includes me, there is no doubt about the power of the 535 engine as such.

 

[sam2019]

I hope this shades some light on the topic. Peace.

to be clear: I meant they are lying with stating that 19.8 RWHP is the real power of the 535 when adding ONLY their head gives 36 RWHP.
apparently (and also stated in the Hitch document) dynos can be misleading in that their baseline is very different.

it would be interesting to know what their dyno would say to a stock Hima - it should be in the 14 RWHP range then.

All I can say is this: I have sold my 535 long ago but when I owned it I also owned a 500 Bullet and for a short while I considered exchanging the engines as the 535 CLEARLY was the superior bike in terms of power. My ass may not be the best absolute measuring instrument but it certainly can discern between 2 individual bikes that I run back to back. I did not go ahead with the exchange bc that would have lead to problems at the RTO bc of engine numbers being checked at owner changes.

Currently I own a 500cc Bullet again (the same one, now with 27.000km on the tacho) and AGAIN the bike is clearly superior to my 411 Hima BS6 with HT-b cam and FuelX pro. Again I say: I CAN discern the power difference between 2 bikes I ride back-to-back.

about dyno charts of Racedynamics: they do lie - and we all know that. if you add ONLY a PT to your stock Hima and hope for the power increase their dyno chart promises you will be sourly disappointed. as Dool pointed out in another post: some people believe advertising is data sharing - dont be such a fool.

 

[sam2019]

Side note to all the well calibrated dyno butts out there: unless your butt knows math, you'll only be able to judge torque, because that is what propels you forward. And that is even more noticeable the more it's down low in the RPM range, since you'll feel a strong push forward when you're going at low speed. So whenever your butt judges a bike powerful, you'd rather use the expression "torquey", unless again your butt knows how to multiply...

well, you are right of course but "torquey" would introduce a new word - power is what everybody understands immediately.

Currently I have access to:

a 500cc Bullet
a stock 411 hima with cam and fuelx
a 500 hima with carb (130 main jet)
a 477 hima with ht-b cam carb (130 main jet)
a factory new Hima unmodified (test ride bike from dealer)

we have a "race track" road with a 1.5 km straight stretch and I can ask a neutral rider (one of the mechanics) to ride them all and evaluate the power. its not a dyno but it is the closest thing we can get to one without a real dyno and for comparison it should suffice.
There is also a gps based app that allows to register acceleration data which would make it a bit more objective.
reasonably one could reach 110-120kmh on this stretch.

 

[Dool]

Well, put all 5 bikes against each other and do that test, I do not understand what it would prove, or why you mention it.

I only have 2 bikes ( one Butt and access to 1 Dyno ) and, with help have managed to get 48% more power on paper, that does not make me an expert I realize, but compared to subjective recollections of bikes once owned or ridden , well there is no comparison is there?

Seems obvious that the 535 puts out about 2 horses more than my stock 411 give or take a couple, so call it Torquey yes but Powerful No way, the figures show that.

 

[Dool]

• @Sasa this is from Power and Torque Explained,

• "If you add another tooth to the front sprocket, you’ll increase the effect of torque (the thrust). This means faster acceleration, earlier shifting, easier wheelies, and less top speed (if it was limited by gearing)."

Surely he means remove a Tooth?

 

[Dool]

Modified 2 Valve head gives a big Gain here

 

[Sasa]

• @Sasa this is from Power and Torque Explained,

• "If you add another tooth to the front sprocket, you’ll increase the effect of torque (the thrust). This means faster acceleration, earlier shifting, easier wheelies, and less top speed (if it was limited by gearing)."

Surely he means remove a Tooth?

Yes, that was "remove" a tooth. In fact for every tooth you have a gain of 3-5% in torque, which could mislead the dyno, since the dyno measures torque at the wheel and then does the math...

There is a reason why manufacturer state bhp and not rwhp and that is not to rip you off. The real reason is that if you had all the other component in the equation (gearbox, front and rear sprocket ratio) you end up comparing apples and oranges. Industry tries to uniform to a standard, and that is crankshaft because with that value you can truly compare two engines back to back
It is true that what you feel is torque at the rear wheel, not at the crank, but then again drop a tooth on the front sprocket and your bike will feel more "powerful" (torquey) all of a sudden!
Try a trial bike, it can wheelie in any gear just by acting on the gas! the usually have around 20 horses, but a rear sprocket that looks like a satellite dish...

to be clear: I meant they are lying with stating that 19.8 RWHP is the real power of the 535 when adding ONLY their head gives 36 RWHP.
apparently (and also stated in the Hitch document) dynos can be misleading in that their baseline is very different.

it would be interesting to know what their dyno would say to a stock Hima - it should be in the 14 RWHP range then.

All I can say is this: I have sold my 535 long ago but when I owned it I also owned a 500 Bullet and for a short while I considered exchanging the engines as the 535 CLEARLY was the superior bike in terms of power. My ass may not be the best absolute measuring instrument but it certainly can discern between 2 individual bikes that I run back to back. I did not go ahead with the exchange bc that would have lead to problems at the RTO bc of engine numbers being checked at owner changes.

Currently I own a 500cc Bullet again (the same one, now with 27.000km on the tacho) and AGAIN the bike is clearly superior to my 411 Hima BS6 with HT-b cam and FuelX pro. Again I say: I CAN discern the power difference between 2 bikes I ride back-to-back.

about dyno charts of Racedynamics: they do lie - and we all know that. if you add ONLY a PT to your stock Hima and hope for the power increase their dyno chart promises you will be sourly disappointed. as Dool pointed out in another post: some people believe advertising is data sharing - dont be such a fool.

@sam2019 it is not ONLY their head. Look at the picture on the HMC page. There is head, cams, valve springs and the whole shebang. It is not "Head" only. And you didn't read above, all things being equal a cam gave @Dool 4HP. And I brought your multiple source with dynos in the very low 20s (18, 22 and 23 to be exact) which brings it on par with a stock Hima in terms of absolute power (pure number)

Now Bullet, GT535 and Hima are three different anymals because the torque curves are different and from here it come your butt sensation. The bullet has the torque very down low in RPM (torque peaks between 3000 and 3500 RPMs) and the GT has a slightly higher number there, hence it feels more powerful (again wrong word, is more torquey). The hima has the peak torque at 4500ish RPMs in his stock form, so you'd be already moving and feel it less. Your stock hima with fuelX and cam will have the peak torque moved even higher in RPM due to cam. And gear ratio and final drive ratio complicate things even further... You might have the bullet with a smaller sprocket and it would feel a rocket compared to the hima...

Advertiser might lie on the GAIN you get from a product, so the delta between before and after, but they have no interested in making the bike look underpowered.

well, you are right of course but "torquey" would introduce a new word - power is what everybody understands immediately.

Currently I have access to:

a 500cc Bullet
a stock 411 hima with cam and fuelx
a 500 hima with carb (130 main jet)
a 477 hima with ht-b cam carb (130 main jet)
a factory new Hima unmodified (test ride bike from dealer)

we have a "race track" road with a 1.5 km straight stretch and I can ask a neutral rider (one of the mechanics) to ride them all and evaluate the power. its not a dyno but it is the closest thing we can get to one without a real dyno and for comparison it should suffice.
There is also a gps based app that allows to register acceleration data which would make it a bit more objective.
reasonably one could reach 110-120kmh on this stretch.

And then? You'll prove that the bike with the highest torque AND the shorter overall gear ratio will win. And I didn't even take in account aerodynamic resistance (or drag for friends...).
The bullet would probably come 1st or 2nd in this race, because it would get to max speed quicker (lower RPM max torque) than the other, but it would probably max out at 115/120 km/h, whilst the stock hima would reach 130/135km/h but in a much longer stretch. Give it a three/five kilometers stretch and see which one has the quickest overall time.

Oh in case you asked: I've driven also a bullet so I know what I'm talking about.

Side note: my guzzy V65 with only 50horses felt like a rocket in acceleration, much more than my BMW F650GS (with 800cc twin engine and 75hp), but it would eventually max out at 150/155km/h while the BMW would go well beyond 170...
If you really want to compare power, than you should compare sustained max speed (GPS data not speedo wannabe data), drag racing only gives you information (in the short run) about torque and how well you put that on the ground...

 

[sam2019]

Ok, I see your points, well then to come back to the initial points:

29.5 BHP translates to 19.8 RWHP (or someone is lying)

from 19.8 RWHP you get to 36 RWHP by modifying the head (and of course adjusting the ECU accordingly however that is done and add all the other small things like exhaust and air filter that we also routinely do)

If this is the case the idea to up the displacement was a fallacy from the start. we should have just focused on having a 4 valve head for the hima and get it from whatever RWHP to whatever RWHP plus 16 - more than all our combined efforts could do so far.

 

[Sasa]

Ok, I see your points, well then to come back to the initial points:

29.5 BHP translates to 19.8 RWHP (or someone is lying)

from 19.8 RWHP you get to 36 RWHP by modifying the head (and of course adjusting the ECU accordingly however that is done and add all the other small things like exhaust and air filter that we also routinely do)

If this is the case the idea to up the displacement was a fallacy from the start. we should have just focused on having a 4 valve head for the hima and get it from whatever RWHP to whatever RWHP plus 16 - more than all our combined efforts could do so far.

You don't "modify" a head, that is designed from ground up with performance in mind.

There is no fallacy in upping the displacement. You only focus on the highest number, but only tells part of the story. HOW you get to the highest number is another matter entirely.

I'll make you an example: 411 with cam vs 477 with stock cam. To my memory they gave pretty much the same highest number (or very comparable) BUT, and it's a huge BUT, the torque curve of the 477 was way higher in the lower RPMs and that is hugely helpful in everyday ride. So the thing to discuss here is the power band not only the highest number.

And btw developing a new head requires technical skills that are several order of magnitude greater than developing a big bore and an enormous budget (machining from billet, scrap, try again, test, fail, redesign, retest, refail, machine again etc...), all that reflects on the price of the final product... That is why a 4 valves head set is 3000GBP, while a stock UCE head is probably 200$...

 

[sam2019]

You don't "modify" a head, that is designed from ground up with performance in mind.

OK, so what are the disadvantages for a performance head user vs. the stock head user - or asked another way: was RE lazy when they designed the head? could the 4 valve no been made a OEM (ok, little more expensive but really - compared to the price of the bike small I would think)

Is there an advantage to have a 19RWHP bike over a 36RWHP?

 

[Sasa]

OK, so what are the disadvantages for a performance head user vs. the stock head user - or asked another way: was RE lazy when they designed the head? could the 4 valve no been made a OEM (ok, little more expensive but really - compared to the price of the bike small I would think)

Is there an advantage to have a 19RWHP bike over a 36RWHP?

RE designing the head was subjected to numerous constrain.
First of all emission. Designing a head to favour low emissions (read run very lean) isn't the same as designing for raw performance.
Second cheap realization. What's the point of intricate flow conduit if you cannot replicate it with castings or the castings leftovers (that no one reworks) would mess the air flow as you studied it?
Third engineering experience: you need to know what you're doing when designin a 4 valves, 2 valves is simpler and more resilient to design errors.
Fourth R&D costs: why inverst hundred thousand euros of RD in fluid dynamic studies when you have already quite some experience with two valves?.
Fifth design goal: the bike was meant to be a tractor for all terrain, not a track bike, two valves serves you better there because they move the torque curve all on the low end of the RPM range. For the same reason the engine was conceived as a long stroke (or stroker for friend) where the focus is on torque, not power. These engine usually spin really low in RPMs, much like cars, and they don't like to go very high: so what's the point of having a head optimized for high rpms (6000+) when you'r bike redlines at 7000? On the opposide side is KTM: the 390 spins up to 11000/12000RPM but is very poor on low down torque. This because it was conceived for the european market, not the indian one, and it has 4 valves head and a huge TB to let all that air flow. It makes a lot of horses but max torque is at 6000+ RPMs and.
Sixth market analysis: what is the point of designing a bike that could sustain 150km/h+ if your main market has a traffic moving at 40/50km/h average? Isn't cleverer to design a bike for this condition and optimize power/torque delivery for these conditions?

Enough reasons?

Added bonus to cheer you up: look at this video, particularly after minute 5:50, Brian is a fun guy...

 

[sam2019]

watched quite a few of Brians vids, like the guy as well. thanx for the explanations - makes sense.

last question: repeated dynos show the 535 with something like 19 RWHP. RE says it has 29.6 BHP. To my knowledge the difference is the gear, chain and any extra add-ons like the alternator. But does that really take away 10 HP or is RE lying? When Dool dynoed the stock Hima the numbers where much more close (something like 22RWHP vs. 24.5BHP if memory serves).

 

[Sasa]

watched quite a few of Brians vids, like the guy as well. thanx for the explanations - makes sense.

last question: repeated dynos show the 535 with something like 19 RWHP. RE says it has 29.6 BHP. To my knowledge the difference is the gear, chain and any extra add-ons like the alternator. But does that really take away 10 HP or is RE lying? When Dool dynoed the stock Hima the numbers where much more close (something like 22RWHP vs. 24.5BHP if memory serves).

I'd say probaly the right number for the RWHP is aroun 21/22 for the GT535, which would make a loss of around 7hp, and yes that could happen.

You have to take in account the design of the engine into the overall count for efficiency. UCE were pushrod engine, with very agricultural and old design of the component. LS410 is a overhead cam design, which makes it already much more efficient. Manufacturers like to state the best number they got, but in reality production items have a certain variability due to tolerances, assembling, workmanship, etc, so no two bikes are equal. There is a fella who dynoed a stock hima at 18. Probably @Dool had a lucky specimen that clocked at 22 (and that was bad for him, since the chase for the 50% more power could have ended much sooner with a 18hp bike...). On top of everything add that no two dynoes are equal so...

With all these variable I'd say a difference of 7hp between advertising and a dyno run, given the old UCE design, is very well possible. Things were even worse before UCE when the gearbox was a separated unit.

 

[Dool]

How accurate is my 22?
It is the reading given by that stock bike on that dyno and can not be readily transfered as they say different Dynos can not be compared ( Personally I think they are covering their asses there) But if we look at 18 as opposed to my 22 that is a variable of 4 and that's a fair bit.

My 22 is a base reading just to have a base so then I know how far I have come, or not.
Being that I have got to 32.6 I would say 10.6