4K Rpm

[Mitch-12]

i race once a month makes over 100rwhp at with 6200 rev limit needs begger cam to make revs worth it has ported head and when i race 90% would be 100% throttle and has 12 psi so with a bigger cam and springs and bigger valves and bigger extractors i may aswell do 8000rpm :)

[altezzaclub]

my balanced camed 4k

 

Balance is big I'd say, mine will rev, but its growly. Five does the job, it will make 6 but I wouldn't want it higher without a full balance.

 

 

 

 

 

[Evan G]

my first 4k would sound like it was gonna DIE at 4 grand and i didnt go higher than that.

 

these motors really suffer from poorly balanaced bottom ends

[love ke70]

doesnt the how to build a tough 4K thread say theyre fairly safe to around 8K then they start getting all harmonic and cracking shit?

as has been said, speedway guys rev the mcf@$k out of 3ks

[kickn5k]

From what I've heard/read they get a harmonic issue at 8500-9000rpm STD short motor. Fix that with a good balance and sky is the limit.(that's 5k btw)

If I get dared enough and when the 5kte is done and 11 is painted etc. I might try to find that magical limit with barrel ITBs and external mounted injectors. I think the 4k would be best suited for it. As you'd make power and it's still oversquare so it will still rev silly.

Your problem Mitch is that you have a huge belt driven air pump putting massive load on the engine to start with. I'm thinking you might not get power past 7,500rpm. But you have the facilities to prove me wrong.

 

Stu.

[GJM85]

It's gonna come down to the cam and springs ultimately. The bottom end is built like a small block chev... free reving a stock 4k will ping out to 8000. Put load on it and you'll be lucky to see 6500.

N/A a cam with big overlap will rev a lot further as the scavenging effect takes over the flow of gases.

Blown/turbo it comes down to home much boost it will take.

If racing i'd be shifting when the engine reaches peak. No sense in just winding it out unless you're looking for top speed.

Edited October 9, 2011 by GJM85

[altezzaclub]

No sense in just winding it out unless you're looking for top speed

 

ah... Conrod Straight today... 300kph and no backing off! Bad luck for Lowndes, just another lap or two would've done it!

 

 

[Mitch-12]

we ran a fujitsu car at bathurst the chase is pretty fast

[altezzaclub]

the chase is pretty fast

 

 

Shit yes!! The utes were drifting around it, at 250kph+ I assume, and Lowndes made a stunning move overtaking through there with the car sliding and squirming!

 

 

Was it MacConville who was leaned on into the grass down to the corner, and went across the track? You could suddenly see the speed he was still carrying while everyone braking had scrubbed off 100kph.

 

 

[Feral4K]

4K will go to 9500rpm 10000rpm all day hyundai!!!! The feral 4k were running has a huuuge KELFORD camshaft "DATRALLY" spec 500+lift and around 330 degrees duration (yep 330 idles at 1800rpm with around 36degrees of advance) powerband 4500 to 9800rpm twin 45 dellortos seriously ported 3k big port, pacemaker tuned length extractors KAMINARI inlet manifold (redline, lynx etc rubbish for hi rpm) Also none of the frankenstein kinda internal stuff goin on here, the 4k engine was severley overengineered from the factory and can handle an amazing amount of abuse, so no pretty roller rockers datto pushrods or anything, and i wouldnt put holden 202 bits in my lawnmower lol. At the end of the day theyre not expensive engines to start with just rev em till they snap and build a new one hope this helps

[coln72]

A stock 5k bottom end will handle 7500rpm easy enough with trips beyond if neccessary :) Could wind it off the tacho.

[altezzaclub]

In the intervening 12months between these posts philfrederick came along and showed us his twin cam 4K, which hauls 9000rpm with ease it seems...

 

So its all in the top end to make them go!

[JDMJared]

4K will go to 9500rpm 10000rpm all day hyundai!!!! The feral 4k were running has a huuuge KELFORD camshaft "DATRALLY" spec 500+lift and around 330 degrees duration (yep 330 idles at 1800rpm with around 36degrees of advance) powerband 4500 to 9800rpm twin 45 dellortos seriously ported 3k big port, pacemaker tuned length extractors KAMINARI inlet manifold (redline, lynx etc rubbish for hi rpm) Also none of the frankenstein kinda internal stuff goin on here, the 4k engine was severley overengineered from the factory and can handle an amazing amount of abuse, so no pretty roller rockers datto pushrods or anything, and i wouldnt put holden 202 bits in my lawnmower lol. At the end of the day theyre not expensive engines to start with just rev em till they snap and build a new one hope this helps

 

I'm guessing you probably mean "KAMEARI" inlet manifold, they do look a lot better than redline ones (who I'm certain never actually looked at a K motor):

 

http://www.kameariusa.com/4Kproducts.php

 

It's good to know your K motor takes such a punishing!

[snot35]

Mmmm, Kameari, so pretty! If only I could justify that on K.

[JDMJared]

Mmmm, Kameari, so pretty! If only I could justify that on K.

 

If any motor is worth it, it's the K motor!

The manifolds go for about $350 on Yahoo auctions

+ postage to Streeter

+ Streeters commision

+ postage to Aus

You might get one for $500 to your door.

And you know it's going to be top shit, Kameari are the go to guys for L-series - they make a mean looking set of 6-1 extractors.