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K&B 7.5 Ducted Fan Engine

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Old 11-09-2002, 01:14 AM
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S3HD
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Default K&B 7.5 Ducted Fan Engine

I called one of the Ducted Fan gurus in my R/C club and asked if he had one of the K&B 7.5 engines - he has 3! Two are NIB and he sent them to Clarence Lee (10years ago, or so) to have Clarence blueprint and port the engines! They are stamped by Clarence on the engine mounting lug on the left(the serial number is stamped into the face of the right lug).

I asked if I could bring my Whiplash over to see how the engine would fit, and hopefully talk him out of one, if it fit.

It won't fit. The rear case for the rear induction is too long. Even with the engine as far forward as I would safely want to mount it, the opening in the Whiplash is not deep enough.

I will try to post pix if I can borrow a digital camera.

You would have to open it up to the point where you're starting to cut into where the fuel tank well is located.

I've emailed Rick with this info, but haven't heard back(it hasn't been very long), and I feel that this info should be posted to prevent somebody from buying an engine that won't fit.

There may be some creative way to make it fit that I haven't thought of, but with the stock airframe it won't fit.
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Old 11-09-2002, 01:31 AM
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ChuckAuger
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Default Drum induction...

Is a little longer than disk. The OS 46 VXDF is drum induction as well. The OS 46 VRDF is disk, I'm pretty sure the K&B is drum. The drums are good for more RPM, but I don't really know what to tell you. I just don't think any of these engines is gonna be happy with any prop over about 8" diameter with enough pitch to make you happy. One poster said they used an OS 46VRDF with a 9X7 and cut it down til it ran good...but it was on a Dust.

As for disk engines, I have a Rossi 65 in mine...it's short enough on the back to not have to cut anthing from the rear...and with 8411's it balances perfect.. I have one NIB OS 46VRDF left, but I really don't think it is the engine for the job, mine wouldn't come close to balancing with the VRDF...I think the 8411's might be a bit heavy, but they are what I'm gonna use.

Good luck with your engine quest..I know it must be a drag to have an engine on perpetual back order.
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Old 11-09-2002, 02:33 AM
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Default K&B 7.5

Got a K&B 7.5 Front intake, DF they used to make them FI, before things got slow and switched to RI. $120 shipped. I think it has a Perry pump on it will have to check. Rudy
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Old 01-11-2003, 08:29 AM
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Default K&B

I use a 7.5 rear intake K$B on my hyper40 with a apc 9+9 but Iam burning 30% nitro and a full unmuffled pipe, they are drum and not disk like chuck thought, works good but not the real hot set up,the new 48 is alot better, but is bucks and hard to get, but you may have the same problem, I don't know the specs off hand,
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