Reply With Quotehey tahiti with a roost in the air nordic will probably blow by you...(roosts are for show)
NordicSquirt..hey..I was simply being humurous...I am not all an ignorant jerk like some people I have come across on other topics....Just a little about me, I am a driver for the SEAL/S 82ft. MKV boat. It has twin V-12 twin turbo Detroit Diesals, twin KaMeWa jet drives 65cm wide,at a total HP of 5500. I just wanted some sound advice, and thought I would throw some competitive humour in there since that's my nature. I can send you a pic of this beast if ya like.
I value your opinion and plan on asking for advice from you again...sorry bro..
hey tahiti with a roost in the air nordic will probably blow by you...(roosts are for show)
HH I used Holley's formula and came up with the same numbers. However they throw in volumetric efficiency, so ya gotta know that too.
Cubic inches X RPM divided by 3456 .... then multiply that by VE
I don't know how good that formula is, but I won't argue with Holley. Using that formula though it would seem many people are way over carbureted.
i think those formulas are geared more towards cars rather than boats (not saying that the formulas are not good) but its been my experience that you really cant over cfm a jet boat if your carbs are square and in sync
No hard feelings man, my background is as follws: Currently Volunteer FireFighter/working partime as EMT, and Parts store, going to school to be Paramedic. Boats, Cars, Beer keep me from stressing to outer space. BubbleDeck, I agree many boaters are WAY over carb'd. Anyways hope all works out Tahiti. I was having a pissy moment in life, shit happens.
if you use the 750dp you'll need more fuel volume the holley blue won't supply them.clay smith has a good mech 130 gph or mallory 140 will supply it.holleys 4 port volumax reg flows good with either pump.you also need at least #8 line from tank to reg.#6 from reg to carbs.read plugs&jet accordling.i ran same setup bbc 10.5 comp with no problem
CFM formulas aren't worth the paper their written on, [see article in this months Car Craft Mag. by Barry Grant.] First of all 2x4 set-ups are calculated differently because they have twice the venturi area as a single 4 bbl. Case-in-point, Trans-Am Z-28 302" SBC with 2 750 holleys [1500 cfm/smallblock] 435hp 427"BBC [3x2bbls-1200 cfm] 427" Ford FE 2 715 Holleys [1430 cfm] and so on.... A well built BB engine should handle 2x4bbls with a total of 1400-1700 CFM with little or no trouble. Personally I run 2 850 Holleys on a 514" BBF Same set up I ran on the old motor, 466" BBF. and have a 1150 Holley Dom. to run when I'm done with the tunnel-ram
Originally posted by Bubbledeck2:
HH I used Holley's formula and came up with the same numbers. However they throw in volumetric efficiency...Using that formula though it would seem many people are way over carbureted.
Yeah, I took the long way around. I don't know what VE pertains to- it must be the efficiency of the engine to pump air- in other words- backpressure.
Originally posted by triple x tx:
i think those formulas are geared more towards cars rather than boats...you really cant over cfm a jet boat if your carbs are square and in sync
The formula is strickly calculating the air being pulled in- it doesn't differenciate between a car or boat.
However, boats are usually operated in a different enviroment than a car (humidity, pressure, heat, torque loads, etc.), so what may work in a car, may not work in a boat. Your engine will still pull the same CFMs.
I agree, most folks (including me) may be overcarbed in that respect. However, in the heat of Havasu (thinner air), my engine thinks it's at 3,000 feet- I'll take the extra CFMs!
Where's Ray?
http://www.goldenplasma.f2s.com/foru...es/happy25.gif
Wow! You make a big thing out of this one. Tunnel ram work good. They give more top end and the only difference in gas is when you use the extra power it provide your motor.
But, because there is a but, carbs have to be dialed according to it, and that, just experienced engine tuner can do it. Read the Holley books, there are chapters about tunnel rams. Run 2 four barrels, mechanical secondaries, minimum of 800cfm each. It works, I did it at many occasions. I learned in circle track racing and then did it with customer's stuff.
A 2 four is easier to feed since you have four reservoirs. A good mech. fuel pump, 135gph. will be more than what the motor needs.
This is just my experance and what I have been running trouble free for 2 seasons.
I have a BBC 30over 13.5 to 1 compression, clay smith cam #310, mech. fuel pump, 1x4 pressure regulator, edelbrock TR, two 750DP carbs mount in line (making linkage very simple, but requires more time to re-jet),78 main and 80 secondary, basset headers, 100% av gas
The motor start just fine, idles around 1000 and has been know to kick som a$$ on Saturday night. I ski, wake board and tube the kids all day, race at night and then I put the boat away. Maybe I have been lucky, but I believe the key to a successful Tr install is using 750 4150 carbs. and avoid the 660's.
This boat was built with the idea of ite being a family ski boat and I agree with you, a TR is a must for the river (looks).
e-mail me with your number if you have any question.
[This message has been edited by wrightnow (edited August 21, 2001).]
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