hey how many revs can a 4k do before things start evacuating the block

rev it till it sounds like its gonna die then give it a grand more!

9000+

well its got over 100hp at 6200rpm but i feel like bigger cam bigger exhaust more boost and wondering how many frevs the poor little rods will jump out haha

you wont shoot rods out the block or blow cranks on a 4k, (a bad tune and detonation will!)

 

stock rpm is 6250.

 

my balanced camed 4k pulls 7 grand

Bloke I met had a KE30 on the dyno and they had to buy mulitple tach's to verify it was actually spinning over 10,000rpm

so i guess valvetrain will be the next problem..

a local wrecker who races speedway was telling me how he had to get special pistons from the states with 1 inch skirts on the pistons on his 3k, spins 11 grand.

 

ill believe it when ill see it mate

 

edit - crow 4220 double valve springs FTW

Edited October 9, 201114 yr by Evan G

so stock with arp headstuds and boost i wonder how 8000 would go? oh and a cam also has 7k inlet and extractors

it doesnt have a cam yet

OK ive posted about my old KE70'S Engine before but everyone calls BS everytime i do. It was a 4k block, bored 60thou (not sure if id be doing that on something running boost) Fully balanced rotating assembly, HUGE cam and quite a bit of compression, head, inlet, extractors were all ported to flow more and it spun to just over 10,000 RPM and absolutely flew. Made 74rwkw on the dyno but the operator wouldnt turn it past 7000 RPM lol.

 

This was built by a bloke who had 30+ years experiance building speedway motors and this one was originally in his sons KE70 speedway car. Built right they CAN rev hard but like anything once you start pushing the envelope itll shorten the motors life.

 

That motor lasted nearly 4 years and ended up just losing compression and never actuually died ( a mate still has it as far as i know). but i don't think with boost itd be the same story lol.

was the tacho set on 3/6 or 8 cylinder? :P

evan your a fag. factory tacho :) which stopped working after i installed the MSD :(

A stocker will see just shy of 8000 before valve float.

It will rev happily at 7000 all day long. However it may not take many days of that kind of treatment.

I got a total of 24 months of abuse out of a 4k with regular trips to valve float, but wasn't using it it every day.

 

Ultimately, some engines last longer then others, but if you keep a stocker under say, 7200 you should have no troubles. :wink:

in my speedway car when we were starting( we start 1st then snap 2nd) i missed the gear and went upto 12000rpm and thats as high as the tacho goes....