How many different 4.6 nitro motors does hpi make?

[jeff B]

How many different 4.6 nitro motors does hpi make and how can you tell the difference. Thanks Jeff

 

[rcnut14]

right now, they only make 2. the f4.6 and the k4.6.
heres the difference......

as you can see, the are very different. I usually look at the cooling head.

 

[X]

right now, they only make 2. the f4.6 and the k4.6.
heres the difference......

as you can see, the are very different. I usually look at the cooling head.

Actually, rcnut is showing the k4.6 HO, not the standard k4.6. The standard k4.6 looks like this:

http://www.hpiracing.com/en/part/15201

 

[jeff B]

Some one told me that you can tell by how many adjusting screws on carb 2 or 3 but could not remember

 

[X]

Some one told me that you can tell by how many adjusting screws on carb 2 or 3 but could not remember

This is true. The K4.6 and K4.6 HO have 3 adjustment needles. The F4.6 only have 2.

 

[jeff B]

This is true. The K4.6 and K4.6 HO have 3 adjustment needles. The F4.6 only have 2.

Thanks

 

[battyone]

Ok so the newer k 4.6 v 2 roto start engine seems to have a central socket instead of an offset socket for starting the engine. does the standard roto starter still fit these and are they powerful enough without the gear reduction from the older style? has 4 savage x trucks and want to upgrade to a new engine. I also don't like pull starters. as I find I need 3 hands to prime and start a cold nitro engine with a pull starter. Or...perhaps I can swap out with a k 5.9 engine will they fit in the savage X chassis?

 

[rcnut14]

do you mean a backplate such as this?

if so, then you need a hex shaft. the rotostart uses a ball and pin shaft. you can buy hex shafts pretty cheap on ebay.( just don't use an old allen key. they're too hard of a metal. heres what you need.... http://www.ebay.com/itm/HPI-Nitro-S...433?pt=LH_DefaultDomain_0&hash=item35ecef6c11


and yes, the k5.9 fits in the savage x chassis.

 

[battyone]

Much thanks for that. I may just go for the 5.9 big block then. as they still come factory fitted with the roto start gear reduction backplate. It may also seem ok to just cut the ball and pin shaft down to the hex part of the shaft ( has a spare shaft which is longer to suit the "XL" but I don't own any "XL"s to require an extended shaft length).

 

[rcnut14]

hmmmm.... you might be able to cut it down. it still might break the backplate, I'm not sure.

the starter shaft has a hex on the end, but its in a ball shape, so that less power gets transferred to the backplate. using a full standard hex ( like you would get by cutting it) may deliver too much power and break it. I'm not sure.


if you're planning on getting a new engine, go with an lrp .28 or .32. they will be better and cheaper than the k5.9

 

[battyone]

Ahh... well ok .. I'm actually replacing a LRP .32 as the sealing backplate I found had flogged out the sunken allen bolt recesses causing a major air leak
as it isn't alloy but composite plastic. if I can find a new replacement I will but hard to as e bay (where I do my shopping) only seems to have them from
factory with a pullstart . where as the 5.9 are listed at roughly 1/2 the price. fitted with standard roto start. Although I did aquire the LRP 2nd hand I still had several years of good runtime with it but always had the faulty backplate leak issue. Thanks again for your advice. To buy locally ( an hours drive to nearest hobby shop) stocking such engines sells at almost 3 times what I can get them online for.

 

[griff7373]

hmmmm.... you might be able to cut it down. it still might break the backplate, I'm not sure.

the starter shaft has a hex on the end, but its in a ball shape, so that less power gets transferred to the backplate. using a full standard hex ( like you would get by cutting it) may deliver too much power and break it. I'm not sure.


if you're planning on getting a new engine, go with an lrp .28 or .32. they will be better and cheaper than the k5.9

WHAT!!!!!!!!!
It doesn't matter if it's rounded or straight the same amount of power is delivered as long as you have a good hook up in the backplate. The reason it is rounded is to let you put the shaft in at an angle and still be able to start it. Think of it as an allen wrench with the ball end on the long end of the shaft so you don't have to be straight on to turn the bolt.

 

[Jam Racing 1]

I am using a 7/32 long ball ended allen key I cut off to start all of my TigerDrive equipped so I am afraid that rcnut14 is incorrect again....

and you will not be able to cut down a ball and pin style because the hex is way too small to fit that unit you are looking at..... not sure what hex size that one is but using an allen key will be perfectly acceptable.... just take it to the hardware store and buy the size that fits and cut it the right length you need...

 

[blown68ssrs]

if you're planning on getting a new engine, go with an lrp .28 or .32. they will be better and cheaper than the k5.9

+1.
I have the LRP .30 X in mine. It works good and sounds great.

 

[rcnut14]

I am using a 7/32 long ball ended allen key I cut off to start all of my TigerDrive equipped so I am afraid that rcnut14 is incorrect again....

and you will not be able to cut down a ball and pin style because the hex is way too small to fit that unit you are looking at..... not sure what hex size that one is but using an allen key will be perfectly acceptable.... just take it to the hardware store and buy the size that fits and cut it the right length you need...

WHAT!!!!!!!!!
It doesn't matter if it's rounded or straight the same amount of power is delivered as long as you have a good hook up in the backplate. The reason it is rounded is to let you put the shaft in at an angle and still be able to start it. Think of it as an allen wrench with the ball end on the long end of the shaft so you don't have to be straight on to turn the bolt.

look, I cant speak for the hpi niro start, but I broke 2 backplates on my dynamite .28 because I used an allen key. I got a 7$ AE starter shaft, and haven't had the problem since. so I'm going off of my own experience( and what the guy at my LHS said)

allen keys are made of a much harder metal then starter shafts....so they don't flex. too much power gets transferred to the backplate from what I understand.

 

[Jam Racing 1]

look, I cant speak for the hpi niro start, but I broke 2 backplates on my dynamite .28 because I used an allen key. I got a 7$ AE starter shaft, and haven't had the problem since. so I'm going off of my own experience( and what the guy at my LHS said)

allen keys are made of a much harder metal then starter shafts....so they don't flex. too much power gets transferred to the backplate from what I understand.

I just find that hard to believe..... I been using my cutoff allen key for 10 years and have had no problem with the starters at all... I think your LHS guys is full of baloney.....

 

[griff7373]

Power transfer is power transfer it doesn't matter with what, the round end is to give you more wiggle room with the shaft. The flex idea still has me scratching my head I can understand some flex but eventually that flexing is going to stop and then you have power transfer. When you broke your 2 backplates was the engine new? Sounds like to me you LHS was telling you what they thing you wanted to hear. I have been turning wrenches my entire life and that sounds a little out there.

 

[rcnut14]

like I said, it was with my dynamite engine so it may be different.........

the engine is new, but its broken in. both the LHS and dynamite told me not to use an alllen key. once I use a starter shaft, I never broke one again. so I'm just going off my own experience.