Belly Tank Build Diary

[WOODY@DDLLC]

https://www.youtube.com/watch?v=UOWquP1k6Oc

[Mike Brown]

https://www.youtube.com/watch?v=UOWquP1k6Oc

I am thankful that didn't happen when I cut the red wire!

[Mike Brown]

I am making final preparations for the trip to the dyno for a tune up.  The tuner asked for a second O2 bung in the exhaust.  With multiple bends in the exhaust where it exits the body they cannot get the normal probe in sufficiently far to assure accurate readings.  They will install a wide band sensor in the additional bung to assist with tuning.  I machined a screw in plug to seal this bung up when not being used.  I removed the header wrap (it is secured in place with hose clamps) to weld the new bung in place then reinstalled it.  I should have worn gloves, the used wrap is certainly some messy stuff.  I am debating on installing a wide band sensor and controller that could be connected to the data logger for real time information. 

[Mike Brown]

The lakester was back on the dyno today for a tuneup to go along with the blower pulley change.  In the original dyno session the car made 480 rear wheel horsepower.  The final pass before shredding a blower belt was 601. 8 (corrected) rear wheel horsepower.  The blower idler that I purchased has a crown and no side flanges which I believed did not work well so close to the blower pulley.  I plan to machine a new idler pulley with a flat running surface and side flanges. 

[Mike Brown]

The dyno and operator are located in Cincinnati Ohio.  The tuner was doing his job remotely from San Antonio Texas.  The marvels of modern IT. 

[Mike Brown]

I started the new blower idler pulley with a 1-3/4" long piece of 3-1/2" diameter 6061 aluminum.  I buy short pieces of metal from speedymetals.com. They are always reasonably priced, have straight cuts and ship the same day of the order.  I drilled a 1/2" hole in the center of the bar so that it could be attached to a mandrel in the lathe. 

[Mike Brown]

The aluminum rod is then bolted to the mandrel in the lathe so that the outside diameter can be machined. 

[Mike Brown]

The new design has a flat running surface for the belt and flanges.  I duplicated the flange geometry that the OEM pulleys have. 

[Mike Brown]

I bored soft jaws for the lathe to hold the pulley accurately from both sides to machine the counterbores for the bearings.  I machined the bearing bores for a "wring" fit since I used Loctite 608 to hold the bearings in place.  I shouldn't have but I did machine a dozen old school 3/8" holes in the new pulley to reduce the weight of the pulley.  I don't expect the pulley to skid on the belt during acceleration, the weight savings will probably not overcome the pumping losses from air moving through the holes but they just look cool.  The new pulley was .224" wider than the original pulley so I had to machine spacers to go between the arm and the doubler plates. 

[Mike Brown]

It was recommended that I use a Gates "green stripe" belt.  These are in their "FleetRunner" series and supposed to be a heavy duty version of their Micro-V belts.

[Mike Brown]

I installed the new idler assembly with a new belt.  The alignment was off slightly which required a few tweaks.  After tweaking and measuring as best as possible in the tight space of the lakester I started the engine and let it run for a period of time.  I rapped on the throttle a few times and did not see any dynamic changes.  In the attached photo you can see that belt is running in the center of the new idler with a little daylight showing between the belt and the flanges on both sides.  I plan to make a few passes at the local drag strip to insure that there are no problems with the blower drive. 

[Mike Brown]

I welded an additional oxygen sensor bung in the exhaust for the dyno tuning session.  I had a wide band O2 sensor and control not doing anything on blown, electronic fuel injected Triumph motorcycle and decided that it would be more useful on the lakester.  So the 10 minute job turned into a couple of hours as I needed to add a relay and fused circuit to properly power the Innovate LC-1 controller.  I installed the system and then connected it to one of the AEM data logger analog inputs.  It was easy to configure this channel to log on the system.  So it is now off to the drag strip to get some useful data on the tune up. 

[Mike Brown]

We took the car to Kilkare dragstrip for another test & tune session.  The blower belt did not slip or shred which was good.  The new blower belt idler pulley worked well.  The O2 data showed that engine was running slightly rich (the plan is for a safe tune up so as to not melt any pistons).  The tune up was supposed to include raising the rpm rev limiter from 6,200 rpm to 6,500 rpm.  With the new shift light working well and expecting to be able to run to 6,400 rpm the rev limiter kicked in at 6,208 rpm shutting the engine down like turning the key off.  That is a horrible feeling as it unloads the chassis until the clutch is pushed in then the big hit when you let the clutch out in the next gear.  So we will be back to the tuner to get that fixed. 

The staff at Kilkare continue to be gracious.  They treat our vehicle as a permanently numbered (NHRA) race car staging us with the pro type dragsters and allow us to make single runs. 

I plan to make another trip to Kilkare to check out the rev limiter setting after it gets set correctly.  I am thankful for these test & tune sessions as they allow the bugs to be worked out before driving 8 hours to find out there are issues.   

[Mike Brown]

I was able to get back to the tuner regarding the rev limiter setting.  The setting was inadvertently not changed.  The rev limiter is now set for 6,600 rpm so I will make a trip back to the drag strip to insure that it works as expected.  I included a gratuitous photo of the car going down the drag strip at speed.  We routinely forget to take photos at the track with trying to figure things being the priority so I took a friend that is a photographer with us.  Photo credit goes to Mark Lopez. 

[Stainless1]

Mike, you might want to talk to your tuner about what types of rev-limiting are available.... if you get there on the salt you do not want the motor to quit and unload...
Killing spark and or fuel to a couple of cylinders at a time would let you know you are there