View Full Version : COLD AIR INTAKE

03-14-2003, 11:51 PM
I am running the 377 scorpion efi in my 18 and find servicing the flame arrestor a pain in the @!#(.It took me an hour to remove it from its location.I am thinking of building a 4in.mandral bent air intake w/k&n filter.The flame arrestor sits behind the hatch and is presently mounted to the transom.The new placement of the k&n filter will be below the forward port air scoop.My question to you is will I loose performance with a 30in.long intake or will it act as a ram air device.Any input would be greatly appreciated.

03-15-2003, 03:40 AM
Kraven, how often are you having to do that anyway?
if it was my fine boat I'd leave it stock! that's a neat setup the way it is and service should only be once a year. if you don't like doing it pay to have it done. :D

that's what the old rat does eek!

HP 600SC
03-15-2003, 04:03 AM
Kraven, dont do it....it will change the way the computer see's the incomming air.....
with regular boating use....you should not have to touch the filter more than once a year if that.
Leave it alone......

<small>[ March 15, 2003, 11:00 PM: Message edited by: HP600 SC ]</small>

03-15-2003, 07:39 AM
Thanks for the info,I do have it winterized at a shop but when I pulled it yesterday,it was filthy.I spoke with mercury marine and they stated it should not affect performance as long as I maintain 4in.thru out.I wil keep everyone posted.

03-15-2003, 08:39 AM
Actually Merc is correct, here it comes,to a point. It really needs to be at least one inch larger in diandter for that distance or the air will generate a vortex and actually srink the actual hole size plus generate some(little)heat. However it is still a Dumb computer and that won't recognize anything is done. That ECM doesn't monitor the airfuel ratio it just guesses. In my opinion I am with Ted, Rat And MP leave it and matain it. The other point is with out the cover that engine is ugly without any dressup goodies, which is one reason they designed such a Lavish cover for it!

03-15-2003, 06:38 PM
The engine cover will remain ,the only think I will do is get air from a different area of the engine compartment.The scorpion cover is as part of the intake system,not just a cover.

03-15-2003, 06:56 PM
kraven, what year is your boat? is the engine stock or swapped in? i'd love to see pics. how do you like that engine?

HP 600SC
03-16-2003, 12:02 AM
Well guess you got YOUR answer then... :p

<small>[ March 15, 2003, 11:03 PM: Message edited by: HP600 SC ]</small>

03-16-2003, 12:22 AM
Is it MAP or MAF fuel injection system? I don't see how it would affect computer at all. In either system the small amount of additional air pressure would be adjusted for by the computer. Your performance would come from a cooler intake charge. One of the biggest mistakes people make is putting that inlet in the engine compartment itself which draws in hot air and actually hurts performance. I am not sure there is exact calculation regarding tubing size and creating airflow turbulence? Most ram air set up tubing size is dictated by the compartment they are put in. Would love to know actual formula if there is one. Use shortest distance to run that filter to an opening in hatch or to a fresh air source. Porsche and 7 series BMW's used to be notorious for hydro locking due to there air inlets sucking in water into intake from low mounted inlets causing some expensive engine repairs. Your air tube should be equipped with a small diameter drain tube in an elbow type configuration to help eleviate this from happening. Fresh cool air means more power. If you have fabrication skills go for it just keep old stuff that you could always swap back on. Rough it out with PVC tubing and rubber connections. If you like it buy some tubing and weld it up. Good luck Brian

03-16-2003, 02:20 AM
hey hp600, check the mid west donzi club site, look under members, michigan, (page 3 i think), then just scroll down to bill kalinowski aka kraven. sweet pic of a sweet boat, in waters i am pretty familiar with.

03-16-2003, 02:23 AM
i just read my own post and........it is occuring to me that i may be spending WAY too much time staring at everybody elses donzi's. i have donzi evy! frown

03-23-2003, 08:14 PM
The 377 scorpion is a fantastic power plant.I have the 1st.18ft scorpion powered DONZI built.We are still in jamacia and will be returning home on 3-30-03.The boat is at home and awaiting a SS cold air intake when I return.I ordered a K&N Filter prior to leaving and hope that this intake as well as prop will take me into the 80's.Will keep you informed with photos as things progress.

roadtrip se
03-24-2003, 12:09 AM
So Kraven,

I have to ask, just can't really resist...

Why did you solicit opinions about this little project, if you had already made up your mind to do it, and were going to ignore what people said here any way?

If it counts, I side with the leave it alone folks.


HP 600SC
03-24-2003, 07:26 AM
Todd, did you see my 2nd reply above??
I was wondering the same thing :confused: