Hobbsy

My Feedback: (102)

I ran the SuperTigre 3000 with the Davis head today.
Fuel==Davis ABC mix.

Just Engines Jen C 19x10==5,500 rpm.
Just Engines Jen C 20x6===6,300

I don't know what to think of this, my Saito 2.20 turns the 20x6 at about 8,100, I expected the converted 1.80 to equal that.

gkamysz

My Feedback: (19)

That's half the power of the Saito 2.20. How about more kerosene and less oil in the fuel? Are you using the stock carb?

Hobbsy

My Feedback: (102)

Greg, I have a ST .90 carb on using the carb adapter, I was hesitant to use the stock carb, it is the same size as the 4500 carb. I'll try it again with the huge carb and see what happens.

gkamysz

My Feedback: (19)

Carb bores can make a huge difference in power. What are the bore sizes of the two carbs?. Remember that the CARB determines the uppper limit of power by limiting the airflow through the engine. I purchased some slide carbs from car .21 size engines and it was way too large for a .40. Well no wonder, the .21 was rated at 3HP. A carb from a .12 at 1HP was the right size. I still have to try it though.

The stock carb if it's the same size as the 4500 might be too large. I think I have this issue with the FS-91 conversion and the stock carb. Poor fuel draw is one problem I'm seeing.

wvarn1957

My Feedback: (3)

One other thing to consider. The big Tigers don't perform well with high oil content. They run best with 8%-10% oil.

Hobbsy

My Feedback: (102)

Thanks WW, but that is not a factor when running as a Diesel.

NM2K

My Feedback: (14)

I'll bet that the larger carb cures the problem. This is rare in Diesels, though.


Ed Cregger

gkamysz

My Feedback: (19)

The .90 is rated at 2.5HP so carb size might not be an issue. I think fiddling with fuel mix would be worth a try.

You wouldn't happen to know what the compression ratio of the Saito 2.20 is?

Hobbsy

My Feedback: (102)

Greg, I have a 2.20 and due its shear size it requires considerable flipping effort. An indication of its compression could be based on the fact that on 5% nitro it runs within a 100 rpm of 10% nitro.

markisenberger

Hobbsy,

Were you able to improve the RPM numbers on you ST 3000 conversion?

I have a DD ST 3000 conversion head I'm contemplating putting on a plane, but your thread gave me second thoughts...

Thanks,

MI

Hobbsy

My Feedback: (102)

Sorry Mark, I did not get to that but I will now that you asked. I have alot of Super Tigre, people keep sending me their bad carbs and riding in a Mail truck makes them good, imagine that.

Hobbsy

My Feedback: (102)

Mark, I will get to the 3000 tomorrow, I've got Church and family stuff today. I ordered a new ST G .90 and a couple of extra ST carbs and a ring for my old S .90K. I will convert the S .90 back to glow (already did actually) and convert the new .90 to Diesel.

[email protected]

Hobbsy, what is the difference between a S .90K and an S .90? I have a couple of ST .90 glows I have been thinking of converting to diesel. Jack

Hobbsy

My Feedback: (102)

Jack, the S .90K has a bolt on front crankcase, the G .90 has a one piece crankcase, other than the backplate that is.

fiery

My Feedback: (2)

Hobbsy ... slightly OT .... but are the J'EN Carbon props re-badged Biela's?

They appear to be so from the pics of them on JustEngines Web Site

Hobbsy

My Feedback: (102)

According to SKYPILOT1 that is exactly what they are, and have three and each arrived in perfect balance.

fiery

My Feedback: (2)

Thought so ... thanks Hobbsy .. I have 3 Biela's and they are a work of art ... and balance perfectly out of the packet. Almost too pretty to put on a model.

I have just ordered a J'EN C carbon prop for a large 4 stroke (ASP 1.80) and I will post elsewhere to (hopefully) confirm.

Hobbsy

My Feedback: (102)

I haven't been able to get to the 3000 for a couple of days, it's mounted in the PSP and ready. I have the carb from my new 2300 on it, the 2300 carb is the same ID as the 3000 carb but has a fat spraybar.

gkamysz

My Feedback: (19)

The fatter spray bar should do the trick. Looking forward to seeing the results. I did end up finding a Saito fuel filter with the bowl at a swap not that long ago. Now I have to make an engine stand like the PSP.

Hobbsy

My Feedback: (102)

It's bitter cold here, I just got in from running the 3000 with the 2300 carb, I can squeeze 6,950 out of it but 6,900 is perfect, Idle is 1,600 and so quiet the prop swishing is mostly what you hear. I may be asking for too much expecting it to match the Saito 2.20, the 2.20 is .42 cu. in. larger and is run on 15% nitro. I want to try a Jen-C 19x10 and an 18x10 ProZinger. It only burbles slightly at idle but is smooth as silk at all other rpm.

Jack, here is a picture of a new G 90 that BigBrown dropped off about one half hour ago and me whom the stork dropped off at 3 AM on April 26, 1942.

dennis

My Feedback: (90)

Hobbsy,
Fit it up for the ST 61 carb and you should be in the ball park.
Oh and your comment about oil not being a consideration is not entirely true. Bab makes a Tartan blend with a little less oil in it because the Tartan has nice roller bearings on the rod and excess oil was slowing the motor down. I ran that stuff in one of my Tigers for over a year and it loved it, but discontinued it's use upon recommendation from the source. However I stripped the motor down and it was well within specs. A noticable increase in performance was noticed using the Tartan mix.
dennis

AMB

Hobbsie got off the phone with Bob davis about 830 Did you post on the 120AX conversion ? he would like to know how
it did martin