Does anyone know the maximum bore for a 5K?

 

Also does anyone know anywhere i could get flat-top pistons for a 5K? The rollaclub wiki reckons aftermarket ones exist... but coventry doesn't sell them.

Mine are 81mm Hypertec Pistons (they are actually for a Gemini and were originally flat tops..........but have been machined down and have been dished to lower the compression to 9.5:1)

 

I have heard of people having 82mm and 83mm Pistons in their 5K's. I would assume that would be about as far as you would want to go. It would suck not having enough thickness in the bore to machine/reco the motor at a later date.

how thin is the thinnest point to a water jacket or another bore in a stock 5k?

 

i think i had about 4mm to water and 7mm to bore in my 4k, you wouldn't want to go much smaller than that, you'll probably get some harmonics up and crack the block above 7000rpm

as Jamie said, 5k's have thinner bore walls. probably why the largest oversized pistons are 1.0mm, compared with a 3k/4k where you can get 1.5mm oversized.

 

with thin bore walls, piston blowby becomes an issue.

Edited October 19, 200521 yr by Felix

www.garrmax.com.au/ for 5k flat top pistons

 

i think u can get up to 40 thou oversize from them & 60 thou off repco

thanks guys :harhar:

oh just in case anyone else here is still teething with mechanical jargon

 

1 millimeter = 39.3700787 thou

how much is this 5k going to cost you?

nick, you scored an ex-rally engine or?..

how much is this 5k going to cost you?

if you're talking to me, hopefully around 1grand all up, honestly i don't really care, it will be completed over time

 

if you were planning on saying "u would be better off doing something else" i've already thought about it. given that I don't have much mechanical knowledge or experience, 5K is a good idea because of how simple the swap is going to be. same gearbox, same mounts, etc. they're cheap too, and go alright from what i hear.

given that I don't have much mechanical knowledge or experience, 5K is a good idea because of how simple the swap is going to be. same gearbox, same mounts, etc. they're cheap too, and go alright from what i hear.

Agreed :harhar: . My 5K cost me $1250 for the completed motor alone. That was a solid lifter conversion too. So your estimate will be in the ball park if you do the assembly yourself.