Thought I would throw another question out for you guys.

I'm fixing to start tuning the engine and working on the blower surge on the new engine. Mark at Precision did the dyno tuning for the fuel mapping for the new cam to get that part dialed in. I did have the Whipple on it before the mods done to the engine.

As far as the blower surge I remember having to take an allen wrench and crack the primary throttle blade to get more air into the engine and play with the idle to take as much blower surge out as I could. I still had problems when turning the hydraulic steering at idle becuase it would put a minor load on the engine and the engine would die. I won't get into the catastrophe at the docks that could happen if it dies when bringing the boat in for docking.

Is there more tips and tricks to adjust the idle or to adjust the timing some to eliminate some of this problem. Before more modifications were done to the engine it was sent to Dustin and he had cleaned some of this up.

I want to try everything I can to adjust myself before sending it to the professionals. I heard if you bring your boat to Mark at Precision he will go out on the water with ya and tune it there with his laptop or something, but that sounds a little expensive.

Thanks,
Shawn

Do you have the side mount Whipple?

oh yeah,,,,its the side mounted one.

Get a custom tune on the water would be the best bet. Even if it cost a little $$$. Also if you are running out of room to keep opening the blade drilling a small hole to let air in can help too. Keep going up on the hole size till you get a desired idle. What type of engine control modual do you have? Aftermarket???

I had the similar problem with my side mount not to long ago, I found the boost reference line that ran to my Whipple piggy back ecu thing was leaking once I secured it the surge went away. Also check you bypass valve on the rear of the blower between it and the intercooler and make sure it is working. With the engine running at idle you should be able to watch it moving back and froth, that is what is supposed to cure the surge; it could have lost its vacuum line or torn the internal diaphragm. I would really like to see a pic of your set up if I could, I have my engine out right now and I am thinking of some other ways rig some things and am curious what kind of things other people have done with their side mounts

I scrapped the whole existing fuel system for one single aeromotive pump and regulator. I have changed the whole configuration on the fuel plumbing. I come out of my pump and through the Whipple to a regulator. Then through the regulator to the fuel rail.

I have a line coming off the regulator that drains back to the fuel fill line thats used for keeping the pressure I need. I don't have anything boost referenced right now. I know I'm going to have to come up with some tricks to get the engine to idle. I still have the piggy back whipple computer with a vacuum hose going to my main ecu.

I'm up for any suggestions since I have done this. Especially using the whipple fuel rail as thru route to the regulator and to the fuel rail on the engine. It is a new design and I'm not even sure it will work, but the engine builder ran it on the dyno with no boost reference of any kind and it ran fine. I wasn't there to check for the blower surge, but now that I have it in the boat its surging big time.

I'm open for suggestions on making this work.

Thanks,
Shawn

Make sure you remove the small brass type breather filter that is screwed into the throttle body. It provides air to the IAC motor. It can get clogged and cause a blower surge that will drive you nuts. Normally Whipples have no blower surge at all because of the bypass valve system. Just take it out and throw it away. I run mine without them in place and they have been fine.

Tyler Crockett did my dyno tuning and one of the first things he did was to drill a hole in the throttle blade we started out small and ended up with a 7/16th hole to smooth out the idle and they idle great at about 800rpm in and out of gear is smooth good luck
Don

Mine ran through the regulator then through the fuel rail and then to the whipple rail for the pre injectors, never had any real issues with this set up. I just received my new comp. and injectors and stuff from Arizona Speed and Marine today when I got home. With the new comp. I should be able to do away with my pre injectors all together and also about half of the wire harness that is now on the motor. Wish me luck with the rewire, I have to repin both of the J1&J2 connectors to make this work. I will post some pics when I get done with the engine. If you have some questions about you surge and fuel set up call Arizona Speed and Marine and talk to Jim, he knows his sh!t and was very helpfull to me on my new set up. (480)753-0208 is the number or www.azspeed-marine.com So lets see some pics of other side mount set ups, we can't be the only two that run them.

Terry

I think this applies to your whipple application as does NA MPI. If you have too much trouble I would call whippl ethey should be able to help also. I remembera thread on soemone having your same trouble just have not found it. Take a look maybe it will help. Not my comments but found from another thread.
You can adjust secondary butterfly to get IAC counts in proper range and idle speed set once throttle position is confirmed at zero also. I had to do this on my stock MPI set up as it was dying at times when put in to gear.

Andy

Some good info here also. http://www.offshoreonly.com/forums/s...ight=IAC+SURGE
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In my humble opinion (IMHO) I think some of the Mercruiser EFI engines needed a little larger hole inside the throttle butterfly for larger boats. A large boat or a high pitch prop drops the idle speed dramatically when shifting. The idle air control valve can't respond quick enough to keep the engine from stalling in some situations (the newer 496/8.1L engines have a different system for idle control that responds faster).

A larger hole will help to supply more air to the engine at idle with less dependency on IAC movement speed.

The best procedure is to install a scan tool and observe the IAC count when shifting in the water. If it is above 40 at an idle (neutral) you will need to increase the hole size.

The engine should be getting enough air through the hole in the butterfly so that it idles at 800 rpm in neutral, at zero IAC count, with approximately 8 degrees of spark advance. This will allow the IAC to open and the timing to advance as soon as the engine is shifted. This will help maintain the correct idle rpm and keep the engine from stalling around the docks.

The size of the hole will vary on certain Mercruiser engines. For example; the Blackhawks had high pitch dual props that needed a larger hole in the EFI throttle butterfly to idle smoothly when shifting, so do the Bravo III dual prop drive EFI engines.

This is one of the difficulties of building an EFI engine and having no idea if the engine is going to end up in a 40 foot boat or a 21 foot boat. You've got to hand it to Mercruiser, these engines are pretty flexible as they come from the factory!

Sincerely
Dennis Moore
Mercruiser Master Technician