I found a service bulletin TS89-072

[Bill Roberts]

http://wac.addr.com/auto/240sx/240sx.html


Scroll down the page.

Does anyone have the complete bulletin somewhere to read exactly what was done and how?

I have searched the site, the web, and even called Nissan. (dealer)

I want to read about how they lowered the compression ratio.

[AKADriver]

Pistons.

Cars built from 7/88-10/88 have a flat top piston, part# 12010-40F10.

Cars built from 10/88-7/90 have a 2.8cc dished piston, part# 12010-30R10.

[deviousKA]

i have a couple threads on this subject at FA. basically the the 8.6:1 have a .020" or slightly larger dish. i dont think it is quite 2.8cc but its about right. i have never seen 9.1:1's in person, but im under the impression that these actually have a slight dome to the piston. there is no such thing as "factory 9.5:1 pistons" which i have only seen 1 place (a website) and part numbers were same as 9.1:1. i was going to offer a sweet deal on the 9.1's but my wholesaler only carries the 8.6. i have looked through most stock aftermarket piston catalogs and none list the 9.1:1 flat top or dome piston. as far as i know the 9.1's are only available from nissan motorsports, and the price is way to high. im still searching for the "magic piston" or to market my high compression ka24e kit. 2 prototypes are in the mix. my pistons will come with 2 top rings in 2mm. also the pin journal must be honed.

just fyi: the early 89 high compression ka24e had 135 hp so other things were also changed beside the unit in the airbox

[Bill Roberts]

Thank both of you for the input. (!)

Actually, I want to get the entire "white paper" of the mod to see about it and learn. I am looking into why mine runs a sold 14.8 to 14.6 on the track 1/4 and sifting through previous documents as well pertaining to the mods the original owner did.

I do have the temp sens, but also I have the boring docs (40 over) and really, all learning is good learning. My date of Manufacture is April 89.

Another thing, 7300RPM is where the 1-2-3 is set.

40/69/94MPH shifts. Max RPM

4th Shuts at exactly 115 on the clock as does 5th.



I want to see if the dealer did the ECU and then look at the other mods and compare for a fuller understanding.

Of course all info is good.

The 25 page PDF file of that bulletin is what I am really after.


I am documenting and comparing at this stage.

(BTW, I did run a solid 6.8second (laser measured) Zero to 60..

So this is why I want to see.


It has the sporting package as well.

[deviousKA]

you could go to your local nissan dealer and see if they have more info on that bulletin and other early ka24e information. your car came stock with the 8.6:1 pistons as well as 140hp. if your car has those miles there would be no reason to go .040 overbore unless someone thought that would improve performance (actually i have no room to talk im at 91mm ) , or just ordered some 9.1:1 90mm pistons. it would be interesting to see the difference between the early and late ka24e powered 240s. particularly the ecu difference. someone told me the early ka24e block was different, well the timing chain anyway there is some difference to be noted, plenty of empty pages in my notebook waiting to be filled