How to roll Crab's RN on flatwater, thanks NWDayton!

[Crab]

Wanted to show all how a seasoned freestyler can take a limited boat and air it out with only 5 minutes total ride time on it. He just came off Daylignts B piped limited, and jumped on my Type4 limited fresh from winter overhaul. You will notice he had to adjust a bit for when it hits to time the setup wake, enjoy.........:hail:

YouTube - Dayton on Jeff's Red Ride @ Tastin n Racin

 

[Kennay]

still have the 62t cylinder on that baby?

 

[Crab]

Yes, stock bore 62T 701 cylinder, type4 dry, no water injection, 35cc domes with 165psi, Protec modified ignition (limiter),12/15 Solas "X" cutback, stock dual carbs. He gave me a lesson, in that its not my boat thats the problem.........

 

[Kennay]

Cool. And further more, that X prop really isn't for lowend is it?

 

[Crab]

Cool. And further more, that X prop really isn't for lowend is it?

Same pear shaped hub as a concord, but with straight blades, more designed for racing. However, I took about 3 degrees of pitch off the trailing edge for more BRAP>>>>>>>>>:aargh4:

 

[Officer Mike]

hey man to me 165 psi seems low for 35cc doesnt it? or am i wrong

 

[Crab]

hey man to me 165 psi seems low for 35cc doesnt it? or am i wrong

T cylinders have slightly higher port timing, and the drypipe's supercharger affect is strong at high rpm, ADA reccomend 37's on an X cylinder.

 

[Mrs Cattledog]

skis lookin good Crab.....

 

[Officer Mike]

thats right my fault. wondering if i shoudl throw my 35s in or leave the 37s.

 

[Crab]

thats right my fault. wondering if i shoudl throw my 35s in or leave the 37s.

Check your cranking compression.

 

[Kennay]

I will be rocking the 35cc's at 180psi in my 62t 760... 75/25 with 93/110 though.

 

[Crab]

I will be rocking the 35cc's at 180psi in my 62t 760... 75/25 with 93/110 though.

I only buy 92 and run good oil 40/1.

 

[Officer Mike]

we are thinking of upping our compression and going to AVgas, its only 70 cents more than we paid today

 

[Matt_E]

Check your cranking compression.

Better yet, check compression ratio.

 

[crashski]

35cc on my ADA head stock bore puts me around 190 PSI.

 

[Crab]

Better yet, check compression ratio.

BTW Matt, Tim thinks your a rollin fool....:woot:I think he liked your boat wake rolls.

 

[Kennay]

Yea, I will most likely mix half and half realistically. It's just the the way gas prices are, make you want to cheap out haha. ~4.25 for 93, and 6.25 for 110. Yikes..... 23.25 for a tank mixed 75/25 or 26.25 for 50/50, hell, guess there isn't a reason not to run 50/50 then

 

[Officer Mike]

Better yet, check compression ratio.

whats the difference?

 

[Matt_E]

BTW Matt, Tim thinks your a rollin fool....:woot:I think he liked your boat wake rolls.

Tim?

 

[Matt_E]

whats the difference?

Cranking compression does not reliably tell you what octane gas you need to run.
Porting, wear of the topend, altitude, can all make a big dent into your cranking compression psi numbers making you think you can run lower octane gas, when in fact your actual octane requirement is much higher.
Cranking ratio = swept volume/dome volume (or to be compressed volume/compressed volume)

Example: In my recent oversized topend, cranking compression was 125psi. Yet I was getting detonation even on premium pumpgas.