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-   -   How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio (https://www.offshoreonly.com/forums/general-q/98301-how-much-intercooled-boost-can-run-9-5-comp-ratio.html)

FASTERDAMITT 03-14-2005 02:51 PM

How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 
If I want to put a Whipple or Procharger on a 9.5cr 572 carbed engine, how much boost can I run on pump gas? I'm thinkin 3-4#'s.

Smitty 03-14-2005 04:58 PM

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 
4 lbs should be no problem. Whipples kits run 5-6 intercooled and that is on 8.75 compression. If it is carbed just richen it up a bit :D

FASTERDAMITT 03-14-2005 06:47 PM

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 
What about AV gas or AV and 91 mix?

chromecat 03-14-2005 07:31 PM

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 
faster,

what kind of boat you looking at ?

Don

BajaIceBreaker 03-14-2005 09:30 PM

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 
This is good info. I am building my motors now, and I am building them with the option to bold on some huffers, maybe next year.
My CR is 9.6:1 454 with Canfield aluminum heads and full roller valve train and head studs already installed.
My engine shop suggested that I have the heads o-ring'd for the head gaskets if I want to run the huffers, but the head manufacturer suggests against o-ringing the heads.
Do you think I can run 3 - 4 lbs. boost safely on 93 octane?
What about head gaskets?

ObnoxiousThundr 03-14-2005 09:39 PM

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 
cometic multilayer head gaskets are unbelievable.

Mike

FASTERDAMITT 03-14-2005 10:22 PM

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 
What's up Chromecat Don,
I ordered a Superboat Y2k 30'er. It was difficult for mr to give up the American Offshore but I wanted a cabin for overnighters and still have a fast boat.
Tom

chromecat 03-14-2005 11:36 PM

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 
good luck...
Don

RumRunner 03-15-2005 08:57 AM

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

Originally Posted by FASTERDAMITT
What about AV gas or AV and 91 mix?

DO NOT USE AV GAS!!!!

DO NOT USE AV GAS!!!!

DO NOT USE AV GAS!!!

Aviation fuel is engineered to run at a lower RPM than standard, or racing gasoline. Most aircraft run at about 3400 RPM Max. It is also designed to run in the thinner atmosphere of altitude. Mixing it with unleaded can actually hurt your performance. I’ve seen many people have problems, and hurt there engines trying to run AV Gas. I have personally done it without any problem, but you have to richen up your mixture to be safe, and then add some lubricants. You’re better off building the engine to run on 89 Octane, and use 93, or add in a little true race fuel.


As far as how much boost you can run with that much compression there are too many variables to answer it with a definitively. Chamber design, Cam selection, porting, headers, head material, ignition timing, and etc. will all play factors. I’ve seen people run as much as 8 lbs of boost on top of 9.5:1 compression. The rest of the engine was built around these factors. Normal cruising however was limited to 4 lbs of boost.

BajaIceBreaker 03-15-2005 09:21 AM

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

Originally Posted by RumRunner
DO NOT USE AV GAS!!!!

DO NOT USE AV GAS!!!!

DO NOT USE AV GAS!!!

Aviation fuel is engineered to run at a lower RPM than standard, or racing gasoline. Most aircraft run at about 3400 RPM Max. It is also designed to run in the thinner atmosphere of altitude. Mixing it with unleaded can actually hurt your performance. I’ve seen many people have problems, and hurt there engines trying to run AV Gas. I have personally done it without any problem, but you have to richen up your mixture to be safe, and then add some lubricants. You’re better off building the engine to run on 89 Octane, and use 93, or add in a little true race fuel.


As far as how much boost you can run with that much compression there are too many variables to answer it with a definitively. Chamber design, Cam selection, porting, headers, head material, ignition timing, and etc. will all play factors. I’ve seen people run as much as 8 lbs of boost on top of 9.5:1 compression. The rest of the engine was built around these factors. Normal cruising however was limited to 4 lbs of boost.

I don't want to pirate this thread, but I think that's what we are looking for. If we have 9.6 (or in his case, 9.25) CR, what does it take to run huffers on pump gas?
I have Canfield 310 heads (as cast) 119CC chambers and Revolution Marine exhaust manifolds, along with everything else noted above.
Can I run huffers? And what amount of boost is safe? Would and EGT Sensor be mandatory in this situation? Do I have to run chillers? Is it a must that I install a bigger gas tank (that's obvious :D )


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