This graph is a result of the case in point, a 124" engine set up to a static compression ratio of 11-1, it has the same cam I'm using fitted and with the intake close  of 43° it would make the corrected compression ratio 10-1 with a CCP of 212psi.

Can someone tell me why this approach seems to be popular and common over there but not here? I have it on good authority it is not a fuel quality issue but that may or may not be the case 

Climate must also play a part. That tuner is up north and they don't have a real summer there. Are they using high ccp like that in places like texas where temps get high like ours?

To get their number I believe you add the research (99)and motor octane (88) numbers and divide by 2, these numbers came from a chart showing BP ultimate specs.

You can also buy higher octane unleaded fuels like VP, Sunoco etc over here but we get buttfucked for them.

My dyna has run at 12:1 and currently sits at 11.6:1, I have no issues filling the tank with "regular". I think the fuel debate is overrated.

If it's pinging, go down one. Lol.

Many years ago you could buy Avgas from the airport !

I don't know if it's actually a thing in the US to aim for a higher ccp, or just a minority looking for a specific build.

I'm sure the run of the mill setup is no different to what we see here.

I'm always surprised at the lack of knowledge of people ( including HD dealers) as to the process of designing an engine build.

I don't know how many times i see the "what bolt in Cam for a stock 103"  question on facebook to be answered by "SE259 mate, goes hard"  !!!

I aim for around 200 psi ccp for a carb' setup.

FI should be safe with 210-215 with a good tune + good fuel.

There are so many variables though, and hard to generalize .

Piston type (dish, flat, pop top) , cylinder head design (squish band surface area,clearance etc ) , cam spec' ( not just inlet timing) and also engine bore/stroke .

And obviously the M8's are a different story again. Twin plug, 4 valve have very different requirements.

Anyway, to the OP ( Monkey, AKA Hilly) whip those heads off, add a little port work, valve job etc, and mill them for some more comp !

A couple of things, first, there is no difference between the American fuel and ours calorific value wise, the calculation of octane ratio is different, if anything the US version is more real world using M/O + R/O ÷ 2 ,ours is R/O only so their number is lower numerically.,so there is no magic in their fuel, their std ulp does seem a bit ordinary though.

43° close on an 11:1 comp engine would be using a performance fuel regardless of how you back work the numbers, even S&S used a 60° 640 cam in their box 124" 10.8:1 comp engine, which is a stellar performer in its own right.[it also stays in one piece with a fair amount of abuse]

We also don't have special road conditions, Utah seems to be around 100°f every day, it was every day i was there, it got a lot hotter at times and it was nothing to see baggers cranked up on the Barstow/Mojave back road blowing their plugs clean.

As for CCP in Twin cams 190/195 is very tunable and also helps the motor in two other ways ,one, higher CCP has presented dets in high temp conditions,another is pumping losses at high rpm, so its a bit of a trade off.

M8's use a lot higher CCP, they also have a completely different combustion chamber, so you have to compare apples with apples, so there are details that need to be addressed in a TC or Evo for that matter if you want to improve the engines efficiency, but we will not get these engines to the M8's thermal efficiency.

A number of people will be impressed with the huge torque at 2000rpm right?  here's a thing, when was the last time you rode your bike say in fifth gear at 1800rpm up a hill and pulled the throttle to the pin? we don't, we use the gear box so the engine scrolls through its rpm range even if we are only using the lower rpm ranges.

All dyno graphs are generated at full throttle,part throttle opening with an engine that makes 2/3 of the hp of a high hp engine will pull the same,all that happens is its ability to produce more torque is limited so hits a wall sooner.

I would say if a person is pushing their bike through its performance range they would take off from a standing start and still be slipping the clutch well into the 3k rev range after launch, don't forget the clutch is a torque multiplier.

I'm hungry,see you later.

BTW I mean question your CCP not the dyno sheet.

with my old TC Carb Dyna I changed to the EVO primary ratio so it was a bit lower geared. And with just the lower gear ratio I saw my cranking pressure go up ( think 10 pounds ) and was using same gauge. friend told me he had same thing happen with race bikes using a different starter motor to turn motor over. As the race bikes use a remote starter.

just thought I'd point this out.

My query about CCP really should of been why some people aim for high numbers?

Is it just for early torque? I don't know.

The dyno sheet was just to show that someone had used a particular cam in a high comp build, not trying to emulate it or talk it up.

Pumping losses is a reason not to aim for a higher CCP, I get that, I read Bill Rooks's book many moons ago and pretty much run with his ideas.

I agree that 190-195 is as high a CCP you would want to keep it street friendly,

Lushy the numbers I got came from this calculator below, it's generally close but does assume some things.

By CCP, to be clear, I mean the reading you get on the gauge when you crank the engine on the starter after its built.

was just about to post the big boyz calculator :)

Also, never take a US dyno chart for granted. Operators of a Mainline will know what I mean. The real heartbreaker haha.

I think people see a Fuel Moto chart, expect the same number then wonder why it's making 15% less.... This was particularly bad in my Chev LS tuning past, workshops were getting creative to have the highest powered bolt on LS in Sydney, strapping, tricking the weatherstation etc. But at the end of the day the blacktop dyno caught them out.

What's the CCP on a SE110 again? It's over 200 for sure.

Thing is if you punch the stock parameters into the above calculator you get nowhere near that number. Odd.

Yes, there will be a difference between CP and cranking speed, people that do this test regularly will know the difference between models. A person I know well will do a CP test as required before tuning to confirm build or eliminate unknowns. High CP’s can result in an engine that  has little spark lead at full power at test temp but still make great power, this engine can have no margin in it at high ambient temps resulting in high speed dets, don’t forget dets don’t go away after 3500rpm, they go into the audible range of your dog. Also I don’t use corrected compression ratios as they mean nothing to me as an influence on a build, i have still yet to work out its relevance if we already know what works.

We can have a cam with identical lift, duration, inlet and exhaust open and close °, but have quite different tdc lifts, the higher the tdc lift the more radical the cam when comparing the two. Years ago I bought the original ‘Accelerator’ program it was a DOS floppy, I could build stuff that had not been invented yet. Then I got ‘Accelerator Pro’ this had a great feature for the time, it had the capability of animating the engine cycle, there are a lot of cams manufactured that have unequal TDC lifts, what was handy you could motor the animation till it generated equal lifts, this was handy when checking valve to valve .Today we have built that many combinations of the TC and Evo that there is pretty much no combo we have not come across before. We still get asked to build the ultimate early smaller engine, why? I cannot understand someone who needs the hottest 80” 30 year old engine ever built when a good 103 will dust it regardless.

we use 10.75:1 a lot with 55° from one cam manufacturer  with good results, yet we see another cam with a 53° close not particularly happy with over 10.5:1 supplied by a different manufacturer.

The M8 presents a different playing field, it runs high CP happily with its different combustion process to the earlier engines, this engine also presents different parameters when modifying, for years we have been sold pistons with a claimed compression given, when we modify M8 top ends the engine runs into a number of different issues that make the comp on the box not as relevant as the + volume of the piston crown.

As Hoody says, the other numbers on the cam have an impact as well. Cheers

If you go over to HTT and read what's written in their dyno section you will see it's not an accidental thing, they aim for a number 200 plus more often than not. I'm not defending anything here, I'm just trying to understand why?