Crash's HPI K4.6 engine mod

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Crash

Crash

Well-Known Member
Messages
3,693
Location
Chicago
OK

This is my second mod job, my Axial went so well I

thought I'd see what improvements could be made

to the HPI K4.6

don't get me wrong the K is a great mill but, I've got

the modding itch now.

Here is th start of it, tear down.

This is a rebuilt HPI k4.6 / new piston / new sleeve / 3 gallons through it

hpik4-11.jpg

hpik4-13.jpg

hpik4-8.jpg

hpik4-3.jpg



The marker represents where I'll be doing the mod work.

On this engine I'm going to follow another school of thought I read in an article.

I will not be modding the crank, just the sleeve. (FOR NOW ANYWAY)

Doing the sleeve alone schould bring up to 15% power gain.`

If I do not see the gains expected I'll take this mod further.
 
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Can't wait to see how it turns out. Kinda starting to get excited now. I plan on doin some motor swapping around in the couple of rc's I've got. So, keep us posted how how the k motor P&P goes and when your ready to do mine.
 
Excuse me Sir Crash, I got a few question. How hard it this to actually do?. How hard is it to do something wrong? Are we talking like if you take 1mm too much off it will f*** your engine up?
 
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My old K4.6 was ported and polished. Makes the thing a @#$%ing BEAST.
 
man i think my 4.1's due for a overhaul lol "not really", but the more i hear about this the more i think i should give porting a shot!!
 
Wow, your really going to town on this!

Thanks again for the pictres, I think these will really help those of us who may dare try this ourself's. If I am understading what your doing, (I haven't read through the link you posted yet, but I may have in the past)

On the pics here, is it the red marks where your going to remove material?

I looked at te pic's you Axe thread and can kind of see that you did make those "L-ish" shapes on the sides of the sleve, but it is hard to tell in the other pic's, to me it looks like you didnot go all the way through on those.

Please, if you don't mind, could you post some after Pics of the parts above? and do the same on the other parts you work on?

I remember readingthe article posted in some PFD's on porting the .25 mill but your pics have helped more than the article did. I just don't know the names for all the parts and for the different areas (holes) on the parts.

Oh, one more question, what kind of pokish would you recommend, I didnt get any polish with my dremmel.

this is awesome!!

John
 
Thats totally killer. Cant wait to see how it all turns out. This beats sending you mill away to some far away land for some stranger to do. Although its not, but it looks rather simple for someone with good hands and patience, which I sadly don't have lol..
 
Thanks guys, I'm excited also. I will get more of a gain from this mill than
I did with the axial.

The higher performance mills are already tweaked from the factory so, you will get less gains.

The not so higher performance mills like the HPI K4.6 there is alot to be
gained

SHIFTPOINT,
yes the marker marks represent material to be removed.
not all ports get modded the same way. and the exhaust port does
not get touched at all.
The article I posted does a good job of identifying the ports for ya and what
not to do.
As far as polishing compound, any kind of polishing compound from ace hardware or menards, ect.
I am going to try to find rubberized polishing attachments decribed also in the article I posted.
 
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we have the rubberized polishing attachments at my work (I snagged a few for my own personal use :D) not sure where we get them...I could ask for you...
 
k0m0d067 said:
we have the rubberized polishing attachments at my work (I snagged a few for my own personal use :D) not sure where we get them...I could ask for you...
Click to expand...

wow, thanks komo.

the cotton ones did not last long at all.

Dan

:resp:
 
Hey Crash ever think you could do this as a part time thing? say a weekend thing? I'v got a new .32 Axial and LRP 28 comming this week and would pay you to modd it for me? Just a thought it sound like your getting really good at it and I would trust you with my power plants. Cheers!:beer:
 
i was thinking of asking him myself actually piper lol!! why not??? crash could make a little extra cash and have a blast to lol
 
Crash said:
wow, thanks komo.

the cotton ones did not last long at all.

Dan

:resp:
Click to expand...


this is the place we order ours thru:

http://www.aronson-campbell.com/index.asp

and these are what they look like/brand name, etc

http://shorinternational.com/WheelPointRubber.htm
(about 1/4 to 1/3 down the page) you'll need a mandrel for them, but aronson-campbell should be able to help you out...ask for cratex points (the item numbers I found on the boxes are CRA-8F and CRA-8XF/fine and extra fine)
 
THANKS GUYS

As far as doing mods for the forum, why not.

The thing to remember about this type of modding is:

1. High performance engines(just example axial 28 rr spec1 ) are already modded to a point where you
will only see aprox. 5% gains from a port & polish . To get more out this mill will require sensitive measure devises
modding the exhaust port to change timeing ect. this is best left in the hands of people like AB mods or RB mods

2. sport engines (just an example hpik4.6 )stand to gain aprox. 5-15% power gain
from a port & polish

That being said, let me finish modding & test my hpik4.6 and I'll post details about the outcome.

Then we can talk about grinding on your expensive mills, I'd love to.

I am a research freak so, if anyone finds any details to doing mods that
I havnt mentioned let me know.
 
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Ok,

I need to thank Shiftpoint for sending me the rubberized polishing bits i needed.

They are perfect, thank you

they came in aprox 10 shapes and have abrasives imbeded into the rubber

They remove material but, leave very little abrasions to polish off.
 
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Crash said:
Ok,

I need to thank Shiftpoint for sending me the rubberized polishing bits i needed.

They are perfect, thank you

they came in aprox 10 shapes and have abrasives imbeded into the rubber

These and some good metal polish and we are golden.
Click to expand...

You got those already? that was fast. I am glad they will work for you.

for anyone interested, Here is what they look like
100_2646.jpg
 
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not trying to one up you shift point but, I took pics too so I'll post them.
savageskidplates015.jpg
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savageskidplates014.jpg
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savageskidplates016.jpg
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You need a better camera, those are too blurry :)

That camera does take great pic's, I remember you said it was a KODAK, which one is it? I am using a KODAK Z760 ist 6Mpix but I think I have it set at 1.7 or 3.
 
Crash said:
THANKS GUYS

As far as doing mods for the forum, why not.

The thing to remember about this type of modding is:

1. High performance engines(just example axial 28 rr spec1 ) are already modded to a point where you
will only see aprox. 5% gains from a port & polish . To get more out this mill will require sensitive measure devises
modding the exhaust port to change timeing ect. this is best left in the hands of people like AB mods or RB mods

2. sport engines (just an example hpik4.6 )stand to gain aprox. 5-15% power gain
from a port & polish

That being said, let me finish modding & test my hpik4.6 and I'll post details about the outcome.

Then we can talk about grinding on your expensive mills, I'd love to.

I am a research freak so, if anyone finds any details to doing mods that
I havnt mentioned let me know.
Click to expand...

sounds like if i had it done on my little 4.1 i would see a fairly big difference hmmmm
 
ShiftPoint said:
You need a better camera, those are too blurry :)

That camera does take great pic's, I remember you said it was a KODAK, which one is it? I am using a KODAK Z760 ist 6Mpix but I think I have it set at 1.7 or 3.
Click to expand...

Kodak v 1233
12 megapixal / high definition / 2 GB

I keep it set at 6MP (4.3) because pics are too big to post otherwise

you cant get much clearer picture than the 6 mp anyway. the 12 mp
setting just makes large sharp clear pics.
 
Just curious. but should'nt the bypass port (1 below the 2 tranfer ports) be pointing in a upward manner? I beileve that pointing downward will have a negative effect on the pressurizing of the crank case. I have only modded just a few engines myself. I'm by far not a expert. I just wanted to make you aware of this before hand you may lose performance instead of gain.
 
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ntenc1 said:
Just curious. but should'nt the bypass port (1 below the 2 tranfer ports) be pointing in a upward manner? I beileve that pointing downward will have a negative effect on the pressurizing of the crank case. I have only modded just a few engines myself. I'm by far not a expert. I just wanted to make you aware of this before hand you may lose performance instead of gain.
Click to expand...

Thanks for the tip.:resp:

I have not done this sleeve yet and will definitly take into consideration what you are saying. Back to the books for me.
 
No problem man. I found a good mod on this engine is to put fangs on the bottom bypass port. One fang in the middle of each transfer port. Also bringing the exhuast port up about .012. This mill will allow you to go this far with out having to modify your crank case. Will def wake this engine up.
 
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