Crash's HPI K4.6 engine mod

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DrtBikDave said:
I have the K4.6 H.O engine. If I was going to Port and Polish mine could I just copy what you did or would it be a little different. If I'm not mistaken the main difference is the crank and piston / cylinder. I have been told that the cylinder has more ports. as for the crank I just know it has a different part number.
Click to expand...

I have never saw the insides of the HO
 
Heyy mate
Well i bit the bullet last night and started on the sleve. i have had a look at your pics today and i have noticed that i have gone even more agressive than you have with your ports. is this going to be good or could this be a bad thing
 
rex_hvn said:
Heyy mate
Well i bit the bullet last night and started on the sleve. i have had a look at your pics today and i have noticed that i have gone even more agressive than you have with your ports. is this going to be good or could this be a bad thing
Click to expand...

hard to say, maybe post some pics

flow work is pretty basic, keep it smooth and try not to change the
angle at which the air enters the cylinder.
 
ok will do i don't have any pics at the present moment but i wil try to get some later tonight
 
Crash said:
hard to say, maybe post some pics

flow work is pretty basic, keep it smooth and try not to change the
angle at which the air enters the cylinder.
Click to expand...


Good point here Crash...... one thing tho is almost all te air enters the ports on the topside, by the time the piston is at the bottom of the port all flow has basically sopped...the most important are is the topside of the ports
 
Nitrojedi said:
Good point here Crash...... one thing tho is almost all te air enters the ports on the topside, by the time the piston is at the bottom of the port all flow has basically sopped...the most important are is the topside of the ports
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How can that be? As the piston comes down it is building pressure under it (in the crank case) I would think that the flow would continue at least until the piston reaches bdc.
 
purenitro said:
How can that be? As the piston comes down it is building pressure under it (in the crank case) I would think that the flow would continue at least until the piston reaches bdc.
Click to expand...



the most flow happens at the highest point of pressure differential...when the piston descends and the ports first open there is the highest point of pressure differential between the crankcase and the combustion chamber, therfore that is the point of the most transfer..by the time the piston reaches BDC the pressure differential is nearly zero...... the angle of the topside of the ports has a much more dramatic effect on engine performance then the angle of the bottom side of the ports..... That is why people can hack their sleeves up and the motors running characteristics will seldom change...alter the angle of the topside of the port even a little and the effects can be quite profound.... IMHO you can do anything you want underneath he ports and it will have almost zero effect on the motor contrary to popular belief !
 
Nitrojedi said:
the most flow happens at the highest point of pressure differential...when the piston descends and the ports first open there is the highest point of pressure differential between the crankcase and the combustion chamber, therfore that is the point of the most transfer..by the time the piston reaches BDC the pressure differential is nearly zero...... the angle of the topside of the ports has a much more dramatic effect on engine performance then the angle of the bottom side of the ports..... That is why people can hack their sleeves up and the motors running characteristics will seldom change...alter the angle of the topside of the port even a little and the effects can be quite profound.... IMHO you can do anything you want underneath he ports and it will have almost zero effect on the motor contrary to popular belief !
Click to expand...


I agree with some of this theory but disagree with alot of it, so I will agree to disagree lol.
 
I brought the K out of storage for some more runtime

I quit running it when it became hard to start.

I tore it down cleaned her up and of coarse I had to
grind on it some more.

The flow work was nice ( there are no current pics of crank and sleeve here, I'll shoot some next time its open)
the crank turned out nice for a newbee
The sleeve is ok, I am much better today then when I did this sleeve

but, no timing changes to the
crank.

so, I opened it 10 degrees


I have been chasing my tail with the axial 32 I was tryn to make
fast

these 28's smoke my 32
 
Last edited by a moderator:
Crash said:
I brought the K out of storage for some more runtime

I quit running it when it became hard to start.

I tore it down cleaned her up and of coarse I had to
grind on it some more.

The flow work was nice ( there are no current pics of crank and sleeve here, I'll shoot some next time its open)
the crank turned out nice for a newbee
The sleeve is ok, I am much better today then when I did this sleeve

but, no timing changes to the
crank.

so, I opened it 10 degrees


I have been chasing my tail with the axial 32 I was tryn to make
fast

these 28's smoke my 32
Click to expand...


Just wait till you try a Picco P3 28 !!!! Your in for a serious treat, I promise you !!!
 
Did you get the results that you wanted? And by taking it further do you mean cutting/grinding out the the center post or divider of the boost port? I have the 4.6 myself and was curious if that was too much or not.
 
filabob1 said:
Did you get the results that you wanted? And by taking it further do you mean cutting/grinding out the the center post or divider of the boost port? I have the 4.6 myself and was curious if that was too much or not.
Click to expand...

no, don't remove that post in a F


what I meant was, I did a timing change on the crank.
 
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