Gas props on nitro rigger

[dwilfong]

David , that stand is ghetto !!!!! Polish that aluminum also !!!!

This ain't no shelf queen. Brutus likes that stand it give him character.

Hell at least he doesn't have wood screws thew the top of the sponsons to hold the boom tubes in.

I didn't build the sponsons !! Lots of epoxy in there too ! You know I'm just breakin stones !!

No not you Tom, break stones. :lol: :lol: :lol:

Don't worry Tom I will spruce him up for the Internats.

 

[dwilfong]

Got some testing in today. Prop Shop 7020/3 preped by Mark Sholund

Don't like the new spray bar in the carb. Hard to set the needle. sounds rich and when leaning it takes the plug still gurgling.

It need more testing to get all the holes and spray bar inside OD right. Also the prop dose not load the eng enough in the straits.

Will go back to a standard spay bar till I get a handle on the eng load with the new pipe. The new pipe works real good lots of power but hard to tune. need lots of load to keep in tune.

I will back down on the CR some more at 8.8 now and bring the squash back to 70% to take some power out of the setup. also go down to 30% nitro from 50%

Never thought to much power would be a problem. But until you can match the eng power to the prop load it is a a tuning dilemma.

If it was a saw boat it would not be a problem but the changing load on a heat race setup is a whole different beast.

Will give it a try net weekend.

David

 

[hugh hargett]

Hard to interpret the graph with such similar colors

 

[dwilfong]

Shorten the Pipe

Will do next time out.

 

[Terry Keeley]

Ninety five plus is strollin' for a heat boat, good job!

Looks like your rpm data might be a bit wonky, You're using the hall (magnetic) sensor right? Mine started to do that too, gonna change the sensor and see if it fixes it.

 

[Ian Inverarity]

David,

Looking at the plot most of the runs seem to be in the 80 to 82mph range, with one spike at 95mph, that is a big jump, did you notice anything like that when you were driving? Have you checked the GPS readings against a radar? I dont have an Eagletree system, but today I was testing a GPS in my hydro and the results are just not right. For example, two consecutive runs with different props, first run Stalker radar say 128.1kph, GPS says 120kph, 2nd run radar says 124kph, GPS says 140kph. I have used GPS in my 101 Seaducer for years with mostly good results but I dont think they can be trusted in fast riggers.

 

[dwilfong]

David,

Looking at the plot most of the runs seem to be in the 80 to 82mph range, with one spike at 95mph, that is a big jump, did you notice anything like that when you were driving? Have you checked the GPS readings against a radar? I dont have an Eagletree system, but today I was testing a GPS in my hydro and the results are just not right. For example, two consecutive runs with different props, first run Stalker radar say 128.1kph, GPS says 120kph, 2nd run radar says 124kph, GPS says 140kph. I have used GPS in my 101 Seaducer for years with mostly good results but I dont think they can be trusted in fast riggers.

I was fighting with the needle to get the tune.It looked like a steam eng out the pipe. I leaned on it too much It took the plug after that run down the back stretch.

this was a new eng and prop setup. also was not hooking up right still needed strut adjustment.

Have to make the slot in the strut longer to raise it more.

Have some bigger props to try but have to raise the strut more to run them. the back would hop at speed with the big props.

will reduce the OD also on a few props.

This was the first break in runs on this eng. the RPMs are me coming off the throttle. it was the break in got skeerd when it pulled over the top.

I will push it a little harder next weekend.

 

[Ian Inverarity]

David,

So you think the 95mph was right? Some of the tuning issues you describe sound a bit like a stinger that is too small?

Ian.

 

[dwilfong]

David,

So you think the 95mph was right? Some of the tuning issues you describe sound a bit like a stinger that is too small?

Ian.

Ya had that problem with the MAC pipe when I first ran it. Had too open it up to .470 That is where the new pipe is at.

Don't have the tuning problems with the MAC 13cc but then don't have the power ether.

The cones on this pipe are very aggressive to build the power. But there is a trade off with harder tuning.

It sucks the fuel I will tell you that. with the MAC pipe it would run at 33 on the BM meter. this pipe is off the scale blow 20.

I will get it just have to spend the time running to find the combo of prop and strut hight.

Just hope the boat will handle it.

David

 

[lohring]

A little off the subject, but I import all the Eagle Tree files to Excel. That way you can easily graph the relevant section, change the time plot, and see the data more clearly.

Lohring Miller

 

[hugh hargett]

The graph looks great Lo I just have trouble distinguishing between the two when they get all tangle up together. For speed id just compare gps to a manual calculation at a few different points and calculate derivation. The difference can be misleading as you may need to decide whats reasonable as slip versus whats just inaccurate.Alot of different things can be calculated from just this data.

David Ive heard about the 101's if the tree is off its only off by a few mph not much i bet.

 

[javier molina]

Something to keep in mind he was on and off the throttle but it does show good data on the boat and engine power.

 

[Terry Keeley]

Something to keep in mind he was on and off the throttle but it does show good data on the boat and engine power.

Except the rpm is messed up... :wacko:

 

[dwilfong]

I'll change the sensor before the next run.