Compression Ratio On A 266 Cam
#1
Posted 27 November 2019 - 06:55 PM
#2
Posted 27 November 2019 - 07:02 PM
Ac
#3
Posted 27 November 2019 - 07:36 PM
Edited by Minigman, 27 November 2019 - 08:18 PM.
#4
Posted 27 November 2019 - 10:08 PM
What Engine have you got ?
And what fuels are you happy to run with?
#5
Posted 27 November 2019 - 10:25 PM
I build a 10.5:1 998cc with a kent 266 and it was very pingy. took about 1cc out of the chamber after this which brought the compression down to where it was more acceptable regarding ping
#6
Posted 27 November 2019 - 11:01 PM
45 years ago, before "Secret black boxes" did things to the engine, we could buy 105 Octane petrol at any garage which could take 11.5:1 in a race engine, but with today's unleaded stuff, 10:1 is pushing it.
#7
Posted 27 November 2019 - 11:53 PM
What Engine have you got ?
And what fuels are you happy to run with?
It’s a 1330. I run RON98 with an additive booster.
#8
Posted 28 November 2019 - 04:51 AM
What Engine have you got ?
And what fuels are you happy to run with?
It’s a 1330. I run RON98 with an additive booster.
Assuming you have the Cam Timed to 106 Degrees, I've calculated the optimum Static CR to be 9.69:1.
#9
Posted 28 November 2019 - 06:56 AM
What Engine have you got ?
And what fuels are you happy to run with?
It’s a 1330. I run RON98 with an additive booster.
Assuming you have the Cam Timed to 106 Degrees, I've calculated the optimum Static CR to be 9.69:1.
how does one calculate an optimum CR? Im really interested as my 998 is going in for a rebuild this winter with a 12g295 ported head and possibly a SW5 or ac dodd Rs/rs+ (lets see) and since the 295 head is unskimmed it would be good to know whats ideal. Planning on using 98-100 gas here in Austria. Yes I know i should consult the engine builder but its good to get other inputs ;)
#10
Posted 28 November 2019 - 08:41 AM
I ran a 1098 with a 295 head and 266 cam with 9.5 CR
It was very torquey, but a bit thirsty.
No probs with pinking or running on.
#11
Posted 28 November 2019 - 09:58 AM
I ran a 1098 with a 295 head and 266 cam with 9.5 CR
It was very torquey, but a bit thirsty.
No probs with pinking or running on.
I once heard LJK Setright give a wide ranging talk about engines, and Octane/Pinking was one of the subsequent questions asked.
He espoused the idea that the piston speed of a long stroke engine made the combustion gasses less likely to pre-ignite.
#12
Posted 28 November 2019 - 10:27 AM
It’s a 1330. I run RON98 with an additive booster.What Engine have you got ?
And what fuels are you happy to run with?
Assuming you have the Cam Timed to 106 Degrees, I've calculated the optimum Static CR to be 9.69:1.
So days of the 10+:1 CR is well and truly over then. I’ve never had an engine built below that before. I think the head will have to be sent off again for further chamber mods. I’ve calculated to go from 10.5 to 9.75 is 3.1cc difference, so quite a bit to be ‘scooped’ out.
#13
Posted 28 November 2019 - 10:44 AM
It’s a 1330. I run RON98 with an additive booster.What Engine have you got ?
And what fuels are you happy to run with?
Assuming you have the Cam Timed to 106 Degrees, I've calculated the optimum Static CR to be 9.69:1.
So days of the 10+:1 CR is well and truly over then. I’ve never had an engine built below that before. I think the head will have to be sent off again for further chamber mods. I’ve calculated to go from 10.5 to 9.75 is 3.1cc difference, so quite a bit to be ‘scooped’ out.
Just fit two best quality gaskets.
#14
Posted 28 November 2019 - 10:48 AM
I would build it to run at 9.75:1.
Ac
Spot on
#15
Posted 28 November 2019 - 10:53 AM
It’s a 1330. I run RON98 with an additive booster.What Engine have you got ?
And what fuels are you happy to run with?
Assuming you have the Cam Timed to 106 Degrees, I've calculated the optimum Static CR to be 9.69:1.
So days of the 10+:1 CR is well and truly over then. I’ve never had an engine built below that before. I think the head will have to be sent off again for further chamber mods. I’ve calculated to go from 10.5 to 9.75 is 3.1cc difference, so quite a bit to be ‘scooped’ out.
Not necessarily.
It depends on the Cam and the Crank Angle that the Inlet closes at.
Longer duration Cams need higher Static Compression Ratios.
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