right after some info to help a fellow enthusiast out for her project...

 

4k heads. what ones have big ports and higher compression etc?

iv heard some engines have high comp pistons and a higher comp head is around too.

 

any ideas? i can check part numbers etc etc but part numbers doesnt tell me port sizes etc!

 

cheers guys :D

4K heads aren't large port, 3K heads are large port and swapping them onto a 4K motor should increase the compression.

justin is correct.

 

also, you can get different 4k pistons to change te compression ratio.

 

but yes.....only the 3K heads were bigport

 

3k and 4k are interchangable with most parts.

 

if you find a 3K bigport make sure to change the valves over to 4k ones, other wise you will probably have seal issues.

ah i thought it may have been something like that

cheers guys :D

Truth must be told, most of the bigport heads came off K motors (1080cc or so), I understand so, anyway. Not all 3K heads are big port.

 

Look for the welsch plug, and they're visibly bigger ports. If you want serious grunt, start with a small port and get out the dremel if you know what you're doing.

 

Cheers

 

R

4K heads aren't large port, 3K heads are large port and swapping them onto a 4K motor should increase the compression.

not all 3K heads are big ports. It seems to be confined to early KE20 3Ks....

thanks guys, this info was meant for me :P

 

so what i got out of these replies was that i should get a 3k head that has big ports?

 

you will have to excuse me, I'm relativly new to modding engines, and this is the first toyota that ive owned, so if i say stuff that doesnt quite make sence, or seems like a simple question, feel free to laugh at me haha - as long as you correct me afterwards :D

Get a 3K head if you want to increase the compression, yes. Though the smallport/bigport dilemma doesn't really mean much else, all that changes is your intake velocity..

allo allo flirty 30.... nice nick :D

 

she plans on using the k series twin carb set up with a reground cam, as its a street engine keeping the ports small would be better, but its her project car so a lumpy pig maybe ok if its power that is being sought!

 

first thing is to decide on the perfromance wanted and drivability....

Open the bores up, Check the inlet manifold port sizes, if it's a small port, use a small port head, if it's not, find a big port. Skim the head a reasonable amount, .050" to .075",clean up the ports, get a nice little cam with about .400" lift, stick it together and it should be a good little thing. No real tricks. :D

Edited February 2, 200521 yr by Redwarf

just need to remember that your trying to polish a turd. They wernt made for big power and hence wont make big power (as opposed to say a 2J)

haha even my mighty 20v pales I'm comparison to a 2j!!

 

saw a jza80 pull 485 rwkw in the weekend....

yep and they'll make 266hp/litre on a stock bottom end.....

 

over 600hp/litre on a modded bottom end....

 

 

 

any motor will make power if you throw money at it...its just a question of how much power.....

 

say you throw $6k at a 5K you'll make 133hp/litre tops. Throw 6k at a SR20DET and you'll be making 150+hp/litre. Throw 6k at a 2JZ and you'll be making 166hp/litre....

Ummm, I'd back my "turd" against most things in most motorsport arena's. You can have a nice little grunty K motor for not a great deal of outlay.

 

I don't remember the title of this post being about SR20's?

 

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

chuck a grand at a K motor and ull have a really good lil weapon.

 

Do ure research before hand, and it will pay off :D