altezzaclub Posted July 28, 2011 Report Share Posted July 28, 2011 I'm not sure those siamese blocks exist! I saw the post where the guy bored the cylinders off-center to get the best wall thickness in the thrust side and wondered if peple were getting confused. I suppose the industrial 4K is a forklift motor! Josh the big cam grinding companies (Wade, Crow, Tighe... there are about 5) offer different cuts on a stock cam. So you pick what sort of performance you want, find which cam cuts will suit, and phone them all up getting quotes. Finally you send your cam and followers off to whoever you want to do the work. They grind the cam and reface the followers to suit & send it back. Costs under $200 all up. There is a terrible temptation to pick a cam that works at higher revs than you will ever drive at. Having a screamer that goes like a rocket from 4500 up to 7500 is great once a week for 30seconds, but you have to drive it to work in traffic all the rest of the time as it coughs and splutters low down, misfires and dies at idle.... be warned! Check out the posts on here about who has what. I picked a Crow 606 for low-down power and its great, pulls over 6000rpm if I ever need it to, but has good lift very early in the valve opening. An advertised duration of 270degrees is all most road cars need. There is a list in here- http://www.rollaclub.com/board/topic/42407-the-girls-ke70/page__p__445727__fromsearch__1#entry445727 Quote Link to comment Share on other sites More sharing options...
WET.K30 Posted July 29, 2011 Report Share Posted July 29, 2011 nah I'm not after huge revs i want a massive amount of tourqe from 2grand to maybe 5grand Quote Link to comment Share on other sites More sharing options...
Mitch-12 Posted July 29, 2011 Author Report Share Posted July 29, 2011 supercharge it Quote Link to comment Share on other sites More sharing options...
WET.K30 Posted July 29, 2011 Report Share Posted July 29, 2011 ....... p plater Quote Link to comment Share on other sites More sharing options...
Mitch-12 Posted July 29, 2011 Author Report Share Posted July 29, 2011 buy a 2wd hilux with a 4l v6 they go way hard Quote Link to comment Share on other sites More sharing options...
WET.K30 Posted July 30, 2011 Report Share Posted July 30, 2011 so what would you guys say is the safest bore upgarde on a 4k? Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted July 30, 2011 Report Share Posted July 30, 2011 Have it measured and see- The castings are not nice even circles, so one side will be thicker than the other. One of the guys who did this moved the bores sideways to get the best walls, which is sort-of what a siamesed block is. Obviously you can bore to 80.5mm, as people have done it without problems. You can get pistons of other sizes, so you could bore to 78 or 79mm, but then you ahve to match the deck height, gudgeon pin diameter etc. One guy used VW pistons. The real question is- "What is the minimum wall thickness you can use?" Quote Link to comment Share on other sites More sharing options...
GJM85 Posted July 31, 2011 Report Share Posted July 31, 2011 (edited) My mis-fortune has come at your benefit. After finally sorting out every possible deadend the problems have continued with my 5k. The issue, discovered today is a 20 thou oversize bore and the standard size pistons. SLAPPITY SLAP SLAP!!! :o This has given me the oppurtunity to take some measurements and compare 4k-c and a 5k bore wall and bore to water jacket thicknesses. First is the 4k then my 5k which is 20 thou over. Adding the 10 and 20 thousandth of an inch increase respectively i've come to the following conclusion... Measurements as follows 5k bore wall- 9.03mm 4k bore wall- 12.93mm 5k bore wall to inner jacket- 6.92mm 4k bore wall to inner jacket- 6.55mm Now i'll say these are not precise, exact as standard measurements. But what it tells me is that if you take the 4k's 75mm bore and 12.93mm bore wall out 5.5mm to 80.5mm, you'll end up with a bore to water jacket wall of 1.05mm. Which is f@$k all! Thank you and good night! Edited July 31, 2011 by GJM85 Quote Link to comment Share on other sites More sharing options...
WET.K30 Posted July 31, 2011 Report Share Posted July 31, 2011 soooo i take it the 5k piston is not an option............ Quote Link to comment Share on other sites More sharing options...
filfrederick Posted July 31, 2011 Report Share Posted July 31, 2011 My mis-fortune has come at your benefit. After finally sorting out every possible deadend the problems have continued with my 5k. The issue, discovered today is a 20 thou oversize bore and the standard size pistons. SLAPPITY SLAP SLAP!!! :o This has given me the oppurtunity to take some measurements and compare 4k-c and a 5k bore wall and bore to water jacket thicknesses. First is the 4k then my 5k which is 20 thou over. Adding the 10 and 20 thousandth of an inch increase respectively i've come to the following conclusion... Measurements as follows 5k bore wall- 9.03mm 4k bore wall- 12.93mm 5k bore wall to inner jacket- 6.92mm 4k bore wall to inner jacket- 6.55mm Now i'll say these are not precise, exact as standard measurements. But what it tells me is that if you take the 4k's 75mm bore and 12.93mm bore wall out 5.5mm to 80.5mm, you'll end up with a bore to water jacket wall of 1.05mm. Which is f@$k all! Thank you and good night! Not that i wish to contradict anyone, and i can only talk from my personal experience when building my twin cam 4k. but.. using a normal car block (not a forklift) i sonic tested the block before i started and the walls were uneven side to side, and front to back by .25mm to 1.5mm so by repositioning each bore to the centre of each individual casting i was able to bore the block to 81mm while retaining a 3mm minimum wall thickness. the absolute minimum wall thickness i would go would be 1.5mm but it would crack eventually. maybe i stumbled upon a freak block, I'm not sure but, it can certainly cam be done and i have been driving mine for 3 monthe with no problems. hope this helps answer some questions -phil Quote Link to comment Share on other sites More sharing options...
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