Difference between Old and New F4.6

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Modified Friction

Modified Friction

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About 8 to10 months ago HPI changed the guts in the motors from what i have been told. What is the difference and if you sit the 2 side by side can you tell which ones which?
 
Thanks f1n3sse for checking the thread out. I was told that there was a bad batch of motors that was breaking cranks. And with the outragous prices in our lhs (and me not knowing any better then) and the fact they don't rotate their stock, i think i might have gotten one cause i bought mine in that time frame. needless to say if it cost more than $0.01 i will not by it from there. The guys at our lhs are such numnuts!!! You can give them a HPI part number and they still don't have a clue and try to charge more than list price sometimes!!! Thats why i always rely on HPISF!!!!
 
I might be Blazer. I figured i would safe to double check on that info here on HPISF. The info was from the lhs which i would be better off talking to my dog than with them!!!! Thanks Blazer!!
 
I never heard of a mill breaking a crank. take to the new generation buy online. I'm a firm believer in helping out the community but i bought my sav x for 385 and my lhs wanted 425...i go there to buy misc parts like after run and shims, items like that.
 
the k4.6 and f4.6 have totally differnt sleeves, I'm only going by pictures on there website, but I'm positive I'm seeing a difference. f4.6 = ofna force 32 look a like, and the k looks like the axial 28 spec1s. hope this helps.
 
If you get on hpi europe and pull up the exploded views you will see the rotating assembly is different. Also great for part numbers.
 
hey f1n3sse my lhs want $489.99 for a x rtr. I would not mind buying from them if they had any product knowledge at all. Thanks blazer i did not think about that i will have to check it out.
 
scrogathon said:
the k4.6 and f4.6 have totally differnt sleeves, I'm only going by pictures on there website, but I'm positive I'm seeing a difference. f4.6 = ofna force 32 look a like, and the k looks like the axial 28 spec1s. hope this helps.
Click to expand...

you on the money the F mill is made by force and the K is made by King star I think I have forgotten. They are completely different mills. But I have no knowledge of the F changing internals at any point.
 
I also had a problem with the first 4.6 broke a crank as well I got a 4.6 about 6 months later real nasty engine not like the first one at all
 
Thats the exact same situation here Trixter. I am just trying to figure out how can you tell the difference between the two.
 
Soulja55 and I were out break in the new motor 2 nights ago and the new motor totally blew his mind compared to the last one!! I will keep you posted Trixter!!
 
this is what a common problem was with this batch of f4.6's

the crank breaks at tdc, and blows the con-rod right through the bottom of the block. kinda makes this weird faint pop noise, and thats it.

n214000867_30439366_1551.jpg


n214000867_30439370_2786.jpg
 
I didn't have the block get smashed like yours but it did snap like that!

Definitely not a good thing to have when you are having fun
 
A few differences that I noticed between the K4.6 and the F4.6 are that the cooling heads are different...the F is perfectly round and the K is slotted. I also noticed a color difference in the blocks as well. Not sure if there are any internal differences.
 
Thankfully I don't think I got one of the bad batch F motors. I have already 1 gallon through my Savage and this thing is STRONG! I can hardly keep the front wheels on the ground. The scary thing is that I just built and installed a 3 speed trans and have yet to try it out. I've been told I am going to need alot of room to run it with the 3 speed.
 
i had 5-6 gallons ion mine when it snapped. it still had really tight pinch for how bad the engine has been abused, and almost got the tires off the ground with extended tvp's and goliath tires.

the k motor has a different owb setup. its internal with the hex piece attached to the starter shaft instead of being the owb like the f motors have.
 
Yep same for me dread....

The motor ALWAYS ran strong all the way until it died at 6 1/2ish gallons....

Have to say that the F4.6 is a strong motor for it to be in the RTR
 
The major internal difference is that the K is a short stroke engine, the F is a long stroke. The K should be able to walk away from the F in the top end due to this. I personaly like the K because I have seen alot of the F's with cracks in the block and broken crank pins. The F is a force engine as well and force doesn't have the best name out there for reliability.
 
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