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  Grease Monkey

  6 years ago

  Something that alludes my understanding is why the USA builders aim for such high CCP numbers compared to what's considered acceptable over here.

  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 

  
  
  

  

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  fatbat

  6 years ago

  Hilly I thought the yanks had access to better quality fuel than us. 

  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?

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  Bigfella

  6 years ago

  Quoting fatbat on 28 Jun 2019 09:53 PM

  Hilly I thought the yanks had access to better quality fuel than us. 

  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?

  Articles I've recently read on the US forums mention between 89-94 octane, can anyone confirm this?

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  Jay-Dee

  6 years ago

  As I understand it their (US) 93 is about the equivalent of our 98, at least octane rating wise.
  

  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.

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  carbon fibre

  6 years ago

  what's acceptable over here??

  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.

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  Grease Monkey

  6 years ago

  Quoting carbon fibre on 28 Jun 2019 11:56 PM

  what's acceptable over here??

  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.

  A CCP of 190ish apparently, what does yours roll over at Stix?

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  Ratbob

  6 years ago

  Quote source removed.

  Yeah, I filled my 68 Mini there, when they closed the pump I sold the car, it just hated unleaded. 

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  paulybronco

  6 years ago

  Quoting fatbat on 28 Jun 2019 09:53 PM

  Hilly I thought the yanks had access to better quality fuel than us. 

  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?

  Quoting Bigfella on 28 Jun 2019 11:00 PM

  Articles I've recently read on the US forums mention between 89-94 octane, can anyone confirm this?

  In my 5 USA trips i can confirm that the fuel is shit! Very low octane causing every bike to ping its head off

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  steelo

  6 years ago

  Quote source removed.

  You can still get it at the Liberty SS 559 Portrush Rd, Glenunga SA 5064. Put a tank full in the Ultra the other week.
  

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  speedzter

  6 years ago

  Quote source removed.

  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 !
  

  
  

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  Lushy

  6 years ago

  GM, I would have to question the numbers. Eleven to one compression, 43 deg inlet close and only 212 psi?  How do I test a 107 TC with 11:1 and 58deg close at 198psi? What gauge are you using? Cheers. 

  BTW I mean question your CCP not the dyno sheet.

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  Krash Kinkade

  6 years ago

  Funny about cranking pressure, if you can spin motor up faster or quicker, you see a higher cranking pressure, than if you spin it slower.

  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.

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  Grease Monkey

  6 years ago

  Thanks for the replies fella's, I had already discounted our fuel as in relation to the title and I understand the octane ratings.

  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.

  
  
  

  

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  brash

  6 years ago

  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.
  

  
  
  

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  Grease Monkey

  6 years ago

  Yeah brash they say in the service manual that in stock form the 110 with the 255's should be between 205-220 I think, no wonder they get hot stock!

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

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  carbon fibre

  6 years ago

  Quoting carbon fibre on 28 Jun 2019 11:56 PM

  what's acceptable over here??

  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.

  Quoting Grease Monkey on 29 Jun 2019 12:08 AM

  A CCP of 190ish apparently, what does yours roll over at Stix?

  200

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  Lushy

  6 years ago

  KK that was in my field of thought when posting. Starter upgrade often improves CCP ?? 

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

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  Grease Monkey

  6 years ago

  Righto, so yep all these things matter, but, why do some people deliberately target a corrected compression pressure way above what is considered safe or right or whatever? What advantages are they chasing? All the reason's not to are in this thread but why do they do it anyway?

  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? 

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  Lushy

  6 years ago

  GM , it is my belief the aim is to produce a stellar torque curve on the dyno sheet in order to sell more parts. That's only my idea though. I may be a little cynical. I guess if doing drag racing it may be ok due to very controlled consistent fuel and very short time of use. ??

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  Grease Monkey

  6 years ago

  Hoody I'm pretty sure around here you are the teacher and if you ever get around to a war and piece on cams there is a receptive audience waiting.