can someone tell me more about this engine?... is that a pump on the back?.. and what rpm might this be rated too?

That's a Perry pump on the back.

A guy at the flying field had one of those on a a Lanier Predator. That was the screamingist 40 size I ever heard.

He'd fly around for a while and every time he would throttle back a little, it would quit.

The Predator had a good glide angle and he always made it back to the field.

He had a tuned pipe on his. I think it was originally in a boat?

It was intended for DF use. Yes that's a pump. It was designed to run upwards of 20K RPM. Not exactly sure how high in the 20's. K&B called it a 7.5, for its 7.5cc displacement. Doesn't it say 7.5 on the right side?

I have one that the late Bill Wisniewsky, who was still working at K&B, modified for me. I was going to use it in a 40-size SWRA warbird racer. I ran into Bill at the Nats, asked him about the engine and told him what I planned to do with it. He said it had a 2-piece crank and that it would eventually break. He said the trick setup was to install a 1-piece boat crank in it, lose the pump and use a 60-size nitro pipe w/muffler pressure; prop it for 18K on the ground.

I wound up sending it to him and he made the changes, sent it back to me. It looks kind of funny because the front housing is rotated 90 degrees CW to accommodate the intake timing of the boat crank. I forgot all about it until I saw your post.

CR

Edited for spelling and typos (grin), CR

HaveBlue....do you have the pipe for it ? I have one almost like yours, it is a pylon racer,
but they are obsolete compared to the Nelson's and the Jett's and such....but it should be
one honkin' little screamer in a sport pylon plane.

FBD.

thats just what I'm looking for!!!


I havent seen the other side but it is listed as 7.5/45 so I would think your right there


I wouldn't know where to get one of those cranks( are they still available????), 18,000 sounds good but the owner say's its good for 26,000 ..not that a prop or df would get it there


Hi FBD , I do have a carbon fiber Bolly pipe but it's on my Irvine .40 fire ..still trying to make the cowl for this sucker, and now Charley susgests a .60 size pipe.. guess I can try it and see ..
I might get the .60 pipe anyways for my ST X series 61 fire ( when I get around to it..or create the funds for it, more accurately..lol)

besides as far as being obsolete compared to Jett and nelson for 1/3 the cost I think its good value ..this one is NIB

As someone else spoke: the engine was made in a inboard/outboard boat version. That one really turned up the revs, I hear. I don't know if the boat versions are still available. Have to ask K&B. One thing about it: Bill sent the original crank back to me. So if you need another, you can have it.

I dug mine out to re-familiarize my self with it. I have the original manuals from K&B. The engine was designed to run around 22 - 23K RPM according to the manual. Another thing that the supplementary sheets lead me to believe is that they were expecting the user to use upwards of 25% nitro. If you'd like, I can scan those sheets and Email them to you, presuming you obtain the engine.

When Bill told me to prop it to run 18K on the ground, I suppose that he was expecting that it would unload to over 20K or so in the air, on a slick race bird. You used to have to cut and try on that kind of deal. Nowadays you can instrument the model in order to find out how much the prop unloads. The .60-size pipe wasn't my idea. It was what Bill suggested. I never tried it out. I have never even run my engine.

Have fun with it,

CR

Have you run that combo? It looks pristene (er, pristine). ;^)

CR

Edited for my bad spelling.

thank you for the offer of scanning the information charley, but it does boil down to me obtaining it first, and I think the original paperwork comes with it too... and yes I probably would be interested in buying the crank as a spare..again that depends on obtaining the engine.. though I imagine a failure would mostly likely occur at speed and I suppose i would need a lot more than just a crank!!!

as for the pipe it sounds like the reccommendation comes from someone who knows..besides I need one anyway

If you want some more info, have a look in the pylon forums...try a search in the "General" section IIRC.

A couple-three months ago I asked a similar question and got some good replies from guys who used to race the K&B 6.5/7.5 series engines.

No, Charley....It's brand new....I have had it for years. Many years ago "Modeler Direct"
was closing out all of K&B's engines when they went to Havasu, AZ. I bought 3 of the 6550's
(.61's) for $65.00 each and one of the pylon engines for $75.00, plus another $35.00
(as I recall ) for the pipe. I should have bought a bucket full of the pylon engines.

I should break down and get a nice Pole-cat or something for it....although not competitive
for racing, it would probably give just about anyone a run for the money at the sport field.

FBD.

I tried to upload some pics of my modified 7.5, hope they came thru OK. Grrr...
I got a duplicate and missed one. I'll try again.

CR

I should have known. Your carb is missing the lo-spd adjusting screw. See the pic for ref. Are you sure that isn't the DF pipe? NOt arguing but it's awfully short.

CR


.

Guys,

I sent one pic twice in the previous post, sorry. The pic with the parts around it shows what Bill Wisniewski sent back to me so that I could use the engine in small warbird racer. Note the remote HS needle.

CR

thank you for the offer of scanning the information charley, but it does boil down to me obtaining it first, and I think the original paperwork comes with it too... and yes I probably would be interested in buying the crank as a spare..again that depends on obtaining the engine.. though I imagine a failure would mostly likely occur at speed and I suppose i would need a lot more than just a crank!!!

as for the pipe it sounds like the reccommendation comes from someone who knows..besides I need one anyway



[/quote]

Sell yoo the crank? Shucks, you can have it. Let me know about the manual & supplementary sheet.

CR

HaveBlue
There's another K&B pylon engine (different model to the one in your photo) coming up tomorrow (Monday) afternoon on that auction site and 15 minutes later an ST 40 pylon engine.

I've also got an Irvine 40 fire with a Bolly pipe but mine's the 40LSR CL stunt engine, quite different to yours. And a brand new Irvine 61 fire .

thanks for the heads up Brian, I will check it out.. there was/is an st 40 plyon engine there now .and that K&B ducted fan 1.00 looks ok too

those irvines sound cool...you remeber mine..it's got all those strange pitts in the piston as if a ballbearing has been jumping up and down in there...weird eh!!!

Hay, blue and under,

I know where I can get a K&B .40 perry pumper. Is it worth anything?

CR

That's from too much oil in the mix. See, it looks like compressed droplets. BT, DT.

CR

that would be a good answer..but the irvine hasn't been run yet

I'm at a loss, then. FOD?

CR

Oil can't do that. I remember that engine now blue and I'm baffled by it especially seeing it's unrun. I can't even imagine how it could be machined like that.

....Gremlins. [X(]

Blue, Charlie,


In the Model Airplane New review (over 25 years ago, by Peter Chinn, if I recall correctly) of the K&B 6.5 engine, which is very similar to the 7.5, he noticed the rear bearing was a pretty loose fit in the crankcase front.

There was clear indication that the outer race turned, while the engine was running.

Although this had no effect on the performance of this engine, which was exemplary at the time (over 14K on a 10x6, only a little less than the Rossi), this was noticeable only upon disassembly of the engine.


The K&B 7.5 can be easily converted to sub 22K use, by simply dropping the sleeve and raising the head accordingly, to decrease the exhaust timing to about 160-165ΒΊ.
It will still respond well to a (longer) tuned exhaust. The mini-pipe in FBD's post will also be usable.

well that then defeats the purpose of getting this engine in the first place..

HaveBlue,


Unless you actually want to have this engine spinning at 22K RPM, or more, the standard timing of this engine is way more than what you want.

For 18-20K you want 160-165ΒΊ and this engine has significantly more.
It is over-propped spinning 18K, probably to below its torque peak RPM.

This may lead to a lean-run, when this engine unloads significantly in high-speed flight.

Any engine propped below its torque peak will unload very significantly. If peak torque is achieved, or surpassed, as it unloads, it could reach ~23K RPM, which will require the high-speed mixture to be set much richer than you normally would, with a normal high performance engine.