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Tech Talk Technical Discussion About The Nissan 240SX and Nissan Z Cars |
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#1 |
Another dead ka-t (pics)
My freinds Ka-t decided to take a dump on him.... He was had just filled his tank with gas, as he was leaving the gas station his car started stalling and shut off. He rolled over to the vacuum and air pump at the station(he didnt get to far), opened his hood a white smoke was flooding out of his valve cover. He had thought that it was a head gasket. When I told him it sounded more like a broken ring, he decided to rebuilt it. When he finally got it all apart he started cleaning up the pistons when.... they fell apart. In all three of the four pistons broken and missing pieces. He was running a t25 of a redtop SR20 on only 7psi.
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#5 |
he sent his ecu to JWT to have it tuned for SR 370cc injector , SR t25 turbo, stock MAF, and full exhaust. the ECU was tuned to run 10psi but he was only running 7psi. I dont think running a little rich could cause that.
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#11 |
Zilvia Addict
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370cc injectors are not enough for 7-10 psi. You were probably at extremely lean points especially when the stock KA ecu likes to advance timing at about 3500 RPMs. Next time spend the money on a good wideband and a map ecu or go stand alone. It will cost less in the long run.
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UGR.....SOMETHING WICKED THIS WAY COMES.... |
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#12 | |
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#13 |
Zilvia Junkie
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stock cast KA pistons suck for turbo. you'll eventually blow a ring land because the rings are so close. one detonation off sync will blow every piston into pieces.
im surprised it lasted as long as it did. my stock KA-T lasted 6 weeks at 10psi with my personal dyno tuned eprom. was pushing about 280whp. then i blew a ring in #4 cylinder.. just rebuild the motor with forged pistons and you'll be fine. its the best 400 you'll spend and it should be able to handle anything that t25 could spin |
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#15 |
Zilvia Junkie
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My wideband 02 read 12:1 flat from Hi throttle map at 3,000RPM all the way to redline with 370's and a T25 on my KA-T. 15-16:1 off boost cruising. It'd fluctuate lean a little off boost, but, ran perfect. Definitely the motors condition before boost determines its overall reliability. My KA was bone stock internally, just was always a strong engine. To date, it's the heathliest KA I had ever driven. KA's are awesome engines, I'm almost sorry I have as much invested into my SR that I do. My daily KA-T with half the money invested would take mine, and most, SR's to cleaners.
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#16 |
compression is unknown. the mileage was 58,xxx. the engine came out of a 96 s14. my friend only used it because low miles and it was free(from another friend who got an sr) like I said it was pretty stock. 96 KA, ssautochrome headers, dump and down pipe, full exhaust, SR injectors, SR t25(7psi) , ssauto front mount, and JWT ECU. He drives pretty easy. Ive only seen him drive it hard once. It was turbo for only 8 months and driven only a handfull of times cause he has two other daily drivers. I knew it wouldnt last that long but I figured it would have lasted longer then it did. and I would have never guess it would crap out with the light driving he does.
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#17 |
Leaky Injector
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12:1 is a little risky. most people will say 12:1 is ok on low boost applications, as it is the "optimal" a/f ratio to tune for in FI, but most of the time it is lower for safety reasons.
being that little hairdryer pumps out so much air, 12:1 might have been a tad on the lean side. depends what kinda timing jwt decided to throw into it and what the base timing was at in the first place. sucks it happened. rebuild better.
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#18 |
Zilvia Junkie
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yeah something isnt right. Only thing I can think of is JWT didnt touch the timing or something, and it started to detonate. Thats the only thing. My timing was left stock, ECU stock, and 10psi was ran through it, and still is. Too bad, cause KA-Turbos are a proven setup if you arent a tard. Assuming it wouldnt last long is definitely not smart, unless you know your friend doesnt do things right (which sounds like he covered his bases well) KA's are tanks, your SR would be blowing oil before before a well tuned KA-T would come close to having a problem. It's all in how you treat them I guess.
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#19 |
Nissanaholic!
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Well, you know it's from detonation.
The ECU was fine, I'm sure...otherwise it would have died in week 1. If the base timing was not recently changed, then rule timing out. ... The fact the ECU was "tuned for 10psi" and he was only running 7 means jack sh!t. MAF based engine management optimizes the fuel based on airflow. 7psi = less airflow as measured by the MAF, so less fuel. ... SO...that leave fuel pressure, or bad gas. If he has a Walbro, or some other upgraded pump...is it hardwired? If not, it might not have been getting enough voltage = low flow. Bad gas...who knows. - Brian
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#23 |
Post Whore!
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wow that sucks.. some one probably went to aggressive with timing and didnt give her enough fuel... ouch
well you live and learn... tear her apart throw some pistons and rods and start again.. ive been on a shitty safc tune for a yr with a stupid big turbo even spiking to 14psi and i still have 180psi across all four on a ka that has 116k on it... timing kills ka not boost
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#24 |
Super Moderator
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Way to fail and bump a two year old thread.
Using the search option is great and all, but try to keep your eye on the post dates.
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