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mach1 454
05-22-2002, 10:14 AM
i have a 20'mach1 jet boat with a 454 . the motor is basicly stock except for the cam and intake maniflod. the carb i have on there now is a 650cfm. (i know thats small for a big block) my question is if i put a 950cfm would that be to big? how much speed do you think i would pick up? it runs good now with the 650cfm but i know im starving it for fuel. please help!!thanx
mach1 454
spectras only
05-22-2002, 12:49 PM
850 Holley vacum or dp sec marine carb! Need no bigger!
Hotcrusader76
05-22-2002, 12:57 PM
I say the 850 is a wise choice, as well as the conservative 750 (tailored to pump so more). Drop me an email. I can build one up for you, and give you some trade in credit on that lil ole'650.
This is an example of my work. I am located in San Diego by the way, and I do make house calls.
http://cgi.ebay.com/ebaymotors/ws/ebayISAPI.dll?ViewItem&item=1829605458&r=0&t=0
http://cgi.ebay.com/ebaymotors/ws/ebayISAPI.dll?ViewItem&item=1829603728&r=0&t=0
Email me at tpcracing76@hotmail.com
Ty
[This message has been edited by Hotcrusader76 (edited May 22, 2002).]
77charger
05-22-2002, 06:01 PM
A 750 dp will work fine at minimum an 850 might only get you 5 more hp over the 750 under 5500.
BlownChevy
05-23-2002, 09:42 AM
Well... will the 950 be too big???? it also has mechanical secondaries.... what sould it be jetted at?
bruleracer
05-23-2002, 09:17 PM
RPM x cubic inches divided by .3456 ( the constant)asuming 100% volumetric efficiency,
will give the cfm a engine will need.
example 5000rpm x 454 divided by .3456=656cfm.Keep in mind all 4x carbs are rated at 1.5 inches of mecury, so at a (zero preasure drop add approx 100 cfm, now we would have a need for a 750 cfm carb,but thats only the air,the fuel mixed along with it displaces approx 8% of the air, so now you would have 750 + 8 % = 810 cfm.
In reality most 91 oct, engines run at a volumetric eff. of approx 90% so now we have 810 cfm - 10 % 810 - 81 cfm = 729 cfm...
a 750 sounds perfect!!! unless ofcourse the engine runs at 6000 rpm and then we start again,,, some fun numbers to play with!!!
hope it helps steve brule'
westech performance