J-Bonz

iTrader: (3)

I was thinking the same thing. I would beleive there would be alot of turbulant air in the engine compartment with high and low pressure zones. Ultimetly equating into different air densities, which could be tough to tune or simulate on the dyn.

RumRunner

Actually you can measure the air pressure using a magna-helic gauge. From there certain dyno setups can actually reproduce these conditions.

HARDCORE A/O

Thanks Smitty. I hadn't thought of cutting the blower inlet snout off shorter, but I see what you mean. I have the hoses routed on the port side Gen III so that water hose comes from the back of the manifold to a 90 degree elbow (facing to the side) on the riser, so that I could eliminate the lower hose fitting on the manifold that sits like right in the middle of the intake.
Rumrunner: I see what you mean. My scoop is the smaller triangle shaped inlet version. I have it mounted in the middle of the hatch (mainly for aesthetics) and I have the vents on both sides of the engine compartment turned rearward (the stock location on A/O 2600s except they turn one side forwards to promote cross-flow of air through the compartment) I have them both turned backwards to allow the air to escape out the sides of the engine compartment so as to allow the airflow to stuff the compartment with fresh air without promoting airflow to travel directly across where the blower inlet is, as I figured this would create a vacuum, which is the point I think you are making. Again, been there done that - my brother used to own a 1980 Trans-Am that we drag raced back in the late 80's /early 90s and once we had installed a tall-ass "Warrior" manifold on it and had to do away with the hood scoop, which we thought would be great for airflow. Turns out the airflow was so good ACROSS the carb inlet that the sucker leaned out (and slowed down). We realized what was happening when we found that the windshield was covered with gas after every pass - the airflow was actually siphoning the gas out of the carb!! The quick fix there was a simple K&N filter. The point you make is a good one, especially in regards to N/A motors that run without any sort of airflow director or air filter system.
I'll see if I can figure out whether the scoop is working. I have the plug for it so I might just tape the sucker up and see what happens. Thanks for the advice.

Now, here's the prelim. report on my shakedown pass: I put the boat in the water yesterday evening for a short while (1 run) just to check that everything is working:

Water temps and pressure, oil press etc. all perfect. oil temps seems too cool, although I only warmed it up and made one short (3/4 mile?) run so probably wasn't enough.
BTW: I don't have my Innovate LM-1 as yet (I'll get it this week, hopefully) so I don't have an A/F ratio to report, but judging from the black, very sooty look of the plugs, the sizes of the jetting (85/97s), PVCRs (.093") and H.S. Airbleeds (.025"), and the way the motor is burbling at midrange, I know its way rich. I going to start by taking some primary jetting out of it to see if that cleans up the midrange.
BUT: with only 5lbs of boost, it went from about 35 mph to 108mph on my Livorsi GPS in about a 3/4 mile run, so I know its got potential. I think the blower belt is slipping, because it made 5 psi flat at midrange and right at the end of the run and I found a lot of belt residue on the blower bracket. I didn't have time to look at the tach (or speedo - thank god for that recall feature!) as I was too busy watching a rapidly approaching coastline but I know its got more in it just as it is, because it was still accelerating when I pulled the stick back. It's burbling in the middle of the run and cleans up in the higher RPMs and pulls like a beast, so I really wish I could have made a few more runs. I didn't want to hassle it without knowing the AFR, so I left well enough alone (for now.
FYI: the prop is a stock B-1 32 and the drive has 1.34 gears.
When I get the LM-1 hooked up and get an A/F reading, I'll report back with how it does with more boost and some tuning.
to be continued....

J-Bonz

iTrader: (3)

Yeah, your right, I didnt think about that. Most of the testing I was involved with was steady-state. Then again, I did progam using DSP software the gov epa highway&city cycle for fuel economy testing.

HARDCORE A/O

The one important thing I forgot to ask is, what effect does placement of the O2 sensor have on AFR?
I've ordered an Innovate exhaust clamp which allows you to shove the sensor into the tailpipe (or open header on a car) and take a reading from inside the tail-end of the pipe (looks like 8-10 inches in from the pics I've seen on the web).
I have to do this because my tailpipes don't have any O2 sensor bungs and I don't want to have to take them off to send them away to have bungs welded in.
Has anybody done this before? What do you think this might do if anything to the accuracy of the reading?

RumRunner

Placement will have a major affect on your WBO2 sensor reading. If the bung or probe is too close to an open end you'll get reversion pulling outside air back in. You will be much better off welding a bung(s) into your pipe(s), at least if it were mine, that's how I'd do it.

HPJunkie

HC, I am in the process of doing exactly what you are doing. I had the bung welded in the riser of my EMI's. I do know that water is not good or it wrecks the sensor. Innovates site says anywhere is ok back further is best. (like what your saying). I couldnt because of the wet exhaust. I am going to run mine on my truck to get used to operation. Keep me (us) posted !

HARDCORE A/O

I tested the boat with the Innovate yesterday. I used an Innovate LM-1 connected to an 18ft extension with the O2 sensor mounted in an Innovate exhaust clamp. This piece is a bit of genius and really saved me a ton of trouble. It inserts into the tailpipe and clamps down with a set screw. I actually tightened the set screw down pretty tight and then safety-wired into unto my hatch hinge to keep it from dropping overboard (turns out lucky I did!) It has two barrels which run into the exhaust pipe one runs straight back to the O2 sensor which sits outside the pipe at the tip. The other barrel returns the exhaust gas sample into the exhaust pipe and has a 90 degree turn at the end. I'm thinking of adding a piece of copper tubing to the intake barrel to extend it further into the pipe to get a better "sample" and also so that we can use it to test a friends wet exhaust setup by putting the tube into the pipe beyond where the water enters the exhaust. Water is definitely not good for the sensor but I don't have to worry about that because I have full dry tailpipes (Stainless Gen IIIs). I would have preferred to have the bungs welded in as well but to take them off and ship them overseas to Stainless Marine (because I wouldn't want anybody else to do it) just to get bungs welded in was just to much trouble. I might consider doing it at some point in the future if the exhaust clamp keeps dropping out - which it did, but I figure it had a right to from the pressure it probably saw - read on...
I made a couple of passes and the clamp held for the first one which ended abruptly when the intercooler hose blew off at 90mph (and scared the living crap outta me!). But it looked like the AFR was in the mid 11s at WOT. Please bear in mind that this was the first time I was using the LM-1 so I had a bit of a steep learning curve. I actually had my brother ride along and read the numbers off the LM-1 so I would know right away if I was running too lean.
I knew the motor was rich from last weekend so I jetted the carb down to 80's in the primaries and left everything else the same. I also installed a 3.85" blower pulley and tightened the belt down as much as I could. (I think its still slipping a little bit but its a good thing!)
So, I put the intercooler hose back on and tightened the clamps as tight as possible. Back in the water, I made a quick burst into the wind with the trim tucked in. SONAFA*****: 112 mph in about a half mile sprint!!! The blower was now making 10lbs of boost and my brother said he saw the AFR fluctuating slightly in the mid 11's. So, I turned the sucker around and brought it up to about 50mph and when I got it into some calm water I opened her up - WTF: felt like my old Camaro on Nitrous!! This thing absolutely screams!! I checked the gauges. Fuel press -18psi, Boost @ 10psi and then I leaned over (because the A/O 2600 has such a crappy clustered up dash) to check the RPMs and saw the tach heading north of 6000 and then - I noticed the GPS at about 116mph, Well sh!t!!!! I lost my nerve and pulled the stick back and then the GPS updated ... 121MPH!!!!
To put this in perspective, I wasn't at full throttle for no longer than a half mile - and, because it was accelerating so hard, just before I glanced at the gauges, I had hit the trim in a touch, so it actually ran this number at a slight negative trim. AND I have a bone stock Bravo 1 32p on the L/U!
I have no idea what this boat will run but I will bet good money it can go past 125 MPH with the right prop. It made so much water pressure that it actual blew my flush-out hose off the INLET side of the sea strainer!!! Somewhere in the middle of the run the Innovate gave us a "Error" signal which we found out was because the the Clamp blew clean out of the exhaust tailpipe. my brother says the reading was till in the 11's when it went.
And Oh, BTW: just in case you wonder if the Gaffrig is right, I've got a back up - my brother had his Garmin E-trex in the pocket of his vest and guess what - that says 121mph too!
All in all, best test day I've ever had

HPJunkie

HC which LM-1 did you get ? I am looking at them and am considering the AUX box option with boost sensor. I dont know how important that is vs rpm etc.

HARDCORE A/O

HP:
I only bought the exhaust clamp, O2 sensor and the 18 ft. extension wire. I actually borrowed a friend's LM-1 and I really didn't have a lot of time yet to get familiar with how it works. He has the LM-1 with the Rpm kit which allows you to log the AFR at various rpm's. I didn't use the rpm kit because I only wanted to get a real-time reading of the AFR. All in all though, it seems pretty simple to use. The obvious advantage of logging the AFR compared to RPM is so that you can identify any potential lean or rich spot as the engine is accelerating. I don't know anything about the Aux Box but the reason I didn't buy one yet is because I couldn't decide which one would be best for me.