tips for engine rebuild, ka24de

hey guys,

blew the engine. the block was relatively stock, head was built. most likely spun a bearing, lost oil pressure.

i had a question about bearings and making hp. are we able to run them loose like the honda guys to squeeze out a little more hp?

if there's someones e-mail address i can e-mail about this kinda stuff, i'd love to have it. to be honest, i'm one of the few 240sx owners i know who is making an attempt to compete with his car. so that means i don't know much about this car as far as racing is concerned.


thanks,

zach
allstock[at]gmail.com

I can't specifically answer your question about the bearings - but from attempting to enduro the car, here's what I've found out on the motor side:

- Oil temps run HOT - even with a cooler, its hard to keep 'em down for long runs.

- Oil starvation in hard right handers is a possibility. Run a decent gauge set with an adjustable oil pressure warning light that you can set somewhat high to see if you are getting drop. I found that mine went down to about 45 PSI, and would wobble its way back to the 70's as the car got straight.

- Water temps get hot with a stock or close to stock radiator. Spring for a very decent sized one, and water temps should no longer be a concern.

- If you get the front of the motor apart, replace the timing tensioners. The bottom one seems to last reasonably well - but I've had a genuine Nissan replacement fail in less than a year after I had put it in. The rat-a-tat-tat of the chain is a sure giveaway that this is needed.

- If its in any questionable shape at all, spring for a real Nissan high pressure PS hose. The aftermarket ones can't seem to stand up to the rigors of racing, and PS fluid ignites pretty nicely off the headers. Yes, I know from experience.

- When you get headwork done at a shop, always check that the oil plug just in front of the 1st intake port on the head is there. And if they drilled it out and replaced it with a threaded insert - make sure the insert is tight.

- Also when getting the headwork done, make sure that the valves can be shimmed once you get it back. I receieved a head from the shop where the valves were way under the limit with clearance to the cam. Nissan doesn't even make shims that small - so they had to redo the work.

what kind of pistons/rings are available to me in 0.040" oversize?

i thought nissan carried some, but they are discontinued, and i don't know where i can find cast pistons! i wanna order some asap.

These guys still list the piston, although you'll probably have to call about the oversized pistons: http://www.everythingnissan.com/

Or, call Lynchburg Nissan - 434.385.7733 - and ask for Riley Curtis. If they're still available anywhere he will know, and he's really kind to racers.

thanks for the reply, i'll try him altho, i've spoken to a few dealers and they have informed me that nissan has discontinued the oversize versions (0.50mm and 1.00mm) for the pistons and rings.

is there any other reliable brand? autoparts usa (kragen/checker) carry the brand clevite, and i see some builders use their bearings, but how good are their pistons?

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- Oil temps run HOT - even with a cooler, its hard to keep 'em down for long runs.
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Do you run a stock oil pan? How about an Accusump or similar pressure saving device?

if anything do some searching about robello engines. I saw online quite some time ago, and a customer had listed the bearing sizings and clearances/tolerances on the motor. considering the 8,000+ rpm levels the robello engine spun too. i'd look into that direction. Aside from going accusump, and getting a crankscraper/windage tray not much else you can do for oil control without getting into coatings and enlarging oil passages.

For cooling. get the system properly ducted. From the bottom, sides, and top. An oil cooler is a must, if you are tracking it for more then 3-4 laps w/o a cooler you are just not thinking properly. If you can run a cam do it. They really wake up the mid/top end on these motors.