An increase in compression with aluminum heads does not necessarily mean you will have to use a higher grade fuel.  For the same reason that aluminum pulls heat out of the cylinder more efficiently than steel, an aluminum headed engine also more readily resists detonation.  So higher compression can be run without the need for higher octane, but only to a point.  Changing from iron heads to aluminum heads and increasing compression by a point or so should not require higher grade fuel.  Looking at the flow numbers of the heads, I think they are geared a liittle more to the performance side but we'll have to wait for dyno results to really see what they do.


Lawrenceville, GA

Paul,

       Not so, the heads will have a TON of deck material, you'll be able to mill them quite extensively. They are already going to be delivered with a smaller than G head combustion chamber, which will raise the static CR over any iron head. Also, as Charlie mentioned, Aluminum heads can be a half point higher at least and have the same octane requirement as iron. John has revised the chamber and relocated the plug, both of which are designed to lower the octane requirement over the iron version. I'll bet these heads will run 9 or 9 1/2 to one on 87 octane. Hows that? 

Frank/Rebop

Bristol, In ( by Elkhart) 

That will be sweet. Then will they be suitable for boosted applications? I'm thinking the compression will still be too high. I'll be at about 10.5:1 if I swap a set on.


Lawrenceville, GA

Charlie,

          I'm guessing, but I'd want to be down around a true 9:1 with a blower.

 Many of the modern engines run 9 or 10 to one with 87 or 89 octane, chamber design has improved a bunch since the early 50's. My 11 to one Triumph MC runs fine on 89 octane, and it's carbureted, no computer.

Frank/Rebop

Bristol, In ( by Elkhart) 

Frank, here's my old Triumph. Don't have it anymore though-been gone several years now.

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

Alan, shame on you, straight pipes! From the front brake that would be a 66 or 67. My Triumph is a 2003, 3 cyl, water cooled. six speed, ThunderBird Sport. Don't have photos, I also have a '68 BSA Firebird, with mufflers!. They don't work much, but they're on it. 

Frank/Rebop

Bristol, In ( by Elkhart) 

It was the kind of loud that one's wife would hate, but your girlfriend would love.



ok, so I tricked you. It's a 70 that I cloned to be a '66 TT, because I always wanted one but couldn't find or afford a rare real one.



Also restored a 69 BSA Victor 441 and sold it at Las Vegas Auction to a Museum collection. very slow-but would go straight up the side of your house. he, he.

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

so i'm the guy who doesnt get the YBM, where's the pics??

i'm hangin here waitin for a pic. LOL.




This ain't no L-Kamino!

Alan,

       The front brake does fool you. I fell for it. I had a 500mx, that I installed a Clews 608 kit and Jerry Branch cylinder head on. Also ran a 36 mm Mikuni, it was farly quick(!) for it's time.

    Buddy of mine timed me at 90 mph, on knobbies, on asphalt. I figured that was about enough!

Frank/Rebop

Bristol, In ( by Elkhart) 

You guys are flooding my head with memories.  Nice bike Alan, I just love the look.  Thoes things still turn my head today.  Where are the Amal Monoblock carbs?  Back in the day (66-69) I used to have a TT clone that I drag raced quite a bit with some success in E super stock class.  1965 T-120 Bonneville, 11:1 pistons, Sifton cams and pushrods, lightened and polished rocker arms, drilled and narrowed timing gears, Joe Mondello ported and polished head, a little nitro when they were not looking.  Best ET 12.15, best mph 108.  Man, do I wish I had that bike today.

Charlie Burns Laton, Ca (South of Fresno)







BurnsRacing981@gmail.com