Cylinder Blocks, Sleeves, Pistons and Heat

OK, here's a question for you guys. I went from a 1229cc kit to a 1260cc kit over the winter and still have the stock block. This is as big as I can go with the sleeves that I currently have installed. Everything was measured and confirmed before boring to make sure it was OK to bore (enough material left in the sleeves). So let's assume that all tolerances are in spec and all work was done correctly. Here's the question -

Would a big block with a relatively small bore tend to run cooler than a stock block with a relatively large bore? I have noticed that the 1260 is running quite a bit hotter than the 1229 did - same block and sleeves remember. I'm wondering if a larger block with the same bore size would run cooler.

In other words, would a big block on its first bore tend to run cooler than a stock block on its maximum bore. For example, maybe a 1327cc kit in a big block would run cooler than a 1260cc kit in a stock block. What do you guys think??

A 1327 in a stock block would have thicker sleeves than a stock KZ1000. Do you know the OD of the sleeves in your 1260?

How "cool" the engine runs actually deals with a lot of complex variables like total surface area radiating heat, how close together the individual heat sources are and the thermal impedance the heat encounters flowing out to the surface. In other words: bigger surface area equals better heat transfer to air but having the internal heat sources farther away from the radiation (cool) surface point raises the internal temperatures which is bad. This is something I'll bet they model with computer sims.

APE Jay wrote:

A 1327 in a stock block would have thicker sleeves than a stock KZ1000. Do you know the OD of the sleeves in your 1260?

1327 in a stock block? :blink: :laugh:

PLUMMEN wrote:

APE Jay wrote:

A 1327 in a stock block would have thicker sleeves than a stock KZ1000. Do you know the OD of the sleeves in your 1260?

1327 in a stock block? :blink: :laugh:

I think Jay is referring to a STOCK big block.
I think what Jay is getting at is the kz bock , sleeves are getting thin at 1260cc’s. this can cause warpage. the sleeve thickness should be .100” min after boring.

My 1327 big block hit 250* easily. My 1200cc stock kz bock runs cooler. usually 180* at cruse.225* when I run it at the track.

I thought 1197 was as big as you could go on a stock 1000 block and 1260 was the smallest big block?

Mark1122 - Where are you measuring that temperature? is that oil temperature in the pan? or cylinder block temperature?

I am just interested because I am planning to go from stock 904 to 1015 which I believe is as big as I can go on stock liner and was wondering how hot that will run compared to what you guys are talking about (maxing out
a sleeve size)

I believe the liner goes down to .060" per side.

I ment 1327 in a big block.

We have sleeves that allow 1260 in a 1000 block without leaking.

kzzone.com/blocks.html

Injected wrote:

Mark1122 - Where are you measuring that temperature? is that oil temperature in the pan? or cylinder block temperature?

I am just interested because I am planning to go from stock 904 to 1015 which I believe is as big as I can go on stock liner and was wondering how hot that will run compared to what you guys are talking about (maxing out
a sleeve size)

I believe the liner goes down to .060" per side.

u want no less than .100" thickness after bore. .080" is getting thin
i'm not sure what a stock 1015 temp would be? 170* ???
anyone??
i have a temp gauge in the oil gallery.
u can get a stock 1015cc kz block (cheap)and bore it to 1075cc's. it is the best mod for the money out there. if u are going to buy pistons and a bore anyways. u may as well find a cheap 1015 block on e bay or from a member.
the only thing u need to be aware of is the 1015cc liner outside diameter. and your cases ID. sometimes they dont fit , and u must grind the cases out a bit.
oh i just remembered , u are talking about a kz650 with 903 block right?

We have a local guy putting stock 1000 pistons into stock 900 blocks/liners just to freshen them up... my buddy's bike has one of these conversions and seems to run fine.

Liner ends up at .060" without any issues - lots of aluminum around it to support load and take away heat.

We never checked the oil temp, but could make provisions to do it somewhere on the block.
Do you have a gauge ridgidly mounted? Your talking the lower gallery under the crank?
170F - is that with an oil cooler?

I do have a stock KZ650 block bored to 70mm (1000 piston) using 900 liners... also comes out to .060" wall liner - this is a bit more aggressive than the above situation as the block is bored out (remove aluminum) to accept that sleeve... more chance for the liner to move around and less aluminum to wick away heat - it is a drag race motor so we are not concerned about too much useage.

i just removed the oil cap from the galley and drilled it to fit a meat thermometer. i just silicon ed the thermometer into the cap.
maybe the bigger bores produce enough more heat to cause issue with thinner sleeves? it seems to be common practice to leave .100" wall thickness.
i think it was APE Jay who said that.

I can't easily find the block measurements at the moment but I'll keep looking - I'm curious now too. I think I actually posted it here and Jay gave it his OK. I'll search for it...

OK, found the thread on KZR. It was started over 4 years ago!! Anyway, here's what I wrote:

From what I have been able to measure with calipers, the sleeve OD is around 3.2400 and the bore is 3.029. That would leave around .211 (.1055 wall thickness) or around .085 thickness at 3.070 (1261cc).Is there a minimum wall thickness for the sleeve to be considered reliable?

Here was Jay's reply from way back when:
If it is indeed a 3.240 ( have never seen that size sleeve in the aftermarket ), then you could put 78 mm pistons in it.

Jay