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Help with rs4 with HPI nitro star t-15 engine

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Old 07-23-2015, 01:50 PM
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mt411
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Default Help with rs4 with HPI nitro star t-15 engine

Hey guys, I could use a little help from someone with experience with the HPI nitro star t-15 engine. Ill try to provide as much information as possible and hopefully someone can shed some insight (I am not new to nitro engines, have many years of experience with nitro motors in cars/airplanes/helis FYI).

This RS4 was purchased used as a supposedly great running car. I received the car, and it looks like it has barely been ran. However, when I tried to start the engine I realized there was problems. First off, It didnt even try to fire up. There was very little resistance while cranking, and when I would put my finger over exhaust to prime it would not even try to draw fuel from the tank. You could actually see air bubbles in the inlet hose moving back towards tank.

After a short period of trying to start like this (setting needles back to stock, etc), I noticed that there was actually a small spray of fuel shooting out of the bottom of the cooling head. It was clear that even though this looked like a hardly used engine, the head was an aftermarket "upgrade". I checked if the bolts were tight, and they were so I proceeded to take the cooling head off to see if there was an obvious problem. When I did this it looked as if it was a head for a completely different engine. I did not see any way that this combustion chamber could be sealed up due to large gap differences, explaining the fuel shooting out of the head and the lack of compression.

The original owner of this car insists that it ran with this head, which I do not believe, but I am just weighing my options of how I want to proceed. I found the original manual for this engine and it shows the stock head (part #15115) along with the underhead button (part #15116).



This car has an aftermarket head that has bolts that line up obviously, but has a built in underhead that doesn't seal the chamber.



I found this image of a HPI .15fe head and it really looks like what this head is.



I am thinking that he upgraded the cooling head with the wrong part, but just looking to see if someone else may be able to confirm. I am not looking to just throw money on this car "trying" to get it running, but just trying to weigh my options. Even if you do not have a solution, any of the following would help:

  • If you own a nitro start t-15, I would love to see a pic of the bottom of cooling head, the underhead piece, and the top of cylinder head. Was unable to find one online.
  • If you have an old stock head for a nitro star t-15, or underhead for this engine that you would let go for cheap, let me know.
  • Links to other popular rc forums sites where I may be able to find an answer, if I don't here, would be helpful. These can be sent via PM so as not to look like advertising for other sites.

Thanks in advance for the help. Would really like to keep this car, but I am not looking for another rc project. I have enough of those! :P
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Last edited by mt411; 07-24-2015 at 12:58 PM.
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Old 07-24-2015, 03:10 PM
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I have a .15FE and the head is totally round without any cutouts, and the head and combustion chamber are one piece, not a button style head.

Does the "upgrade" head fit inside the cylinder liner snugly or is it loose?
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Old 07-24-2015, 03:40 PM
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The upgrade head doesn't even seem to come in contact with the cylinder liner to seal it. The cylinder liner is recessed about 1mm from the top of the block and the head is pretty much flat all the way across. leaving it the same height as the top of the block. The little gasket / washer (part 15117 in pic #1) can just freely move up and down in the chamber it sits in, doesn't do anything as far as sealing.
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Old 07-25-2015, 04:42 AM
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Then you will need to source a head and head button for your engine that fits. The head needs to recess into the cylinder liner. You may have a head for an .18 engine which likely has a larger bore than the .15 engine you have.
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Old 11-18-2018, 09:15 AM
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Khay
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Default The purple head you have

Hi,
I'm based in UK ..I was wondering if the purple head you have is up for sale,I have the Star 15fe engine and looking to up grade the head.
it seems that the upgrades are in the States.
that head you have is defiantly for a star 15fe engine.
many thanks
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