How many blown up KA-Ts

[IvanAtSPRacing]

Just thought I would ask "THE" question. I think this information will HELP others decide what route they choose when they turbo their KA.

In my opinion, there are two types of failures.

First would be melting a motor down or killing it with detonation. This would be from a poor fuel system, poor turbo kit that creeps past the capability of your fuel system, or poor timing control.

Second would be actually breaking the motor. Cracked pistons, ring lands, bent rods, etc

Blown head gaskets could fall under either catagory

Feel free to post up your experiences, if you have never blown your motor let us know what your setup is and how many miles / how long its been running.

Lets make this educational so that others may decide what the best route is for their KA-T.

Thanks.

[IvanAtSPRacing]

I will be the first to chime in. I have blown up two motors now in the PK R&D S13 car. Both times due to cracked ring lands from too much power. Both motors were bone stock the first was the original 91 KA with 115k miles and the second was a 95 motor with unknown miles. Twice in a row I have shown that the stock pistons cant take 400whp for long at all.

Tuning and fueling were never an issue. The pistons werent melted, just cracked. This was using a full stand alone AEM EMS.

[IvanAtSPRacing]

My personal 5speed S14 I blew the motor up when spraying a 250 HP shot of NOS on the dyno here at the shop. I melted the number one piston.

[klattr1]

for me, took chunks out of 4 JE pistons ring lands due to assuming air fuel ratios would be fine at 15 psi with JWT ecu programmed for 72lb injectors and cobra mafs. At first I was pissed but you cant take things like that for granted. Thats why I preach to everyone now about checking air fuel ratios with wideband and confirming or tuning accordingly. I had a chip sent back within a week based on data I logged (airflow, inj. pulse width vs rpms). They told me I was a "special case." It ran perfect and optimal right after that.I learn the hard way sometimes but at least I know now.I've blown 2 stock headgaskets before but every time its been 20+psi. I've had good success with the Cometic headgasket so far.

[CodeWhore]

So what was "special" about your setup? MAF reading lower than actual flow? Low fuel pressure? Injectors on low side of the rated spec? Base timing advanced past 20 degrees? Or did JWT have a brain fart and sent you a wrong program the first time around?

[AZhitman]

I'd also like to hear about those of you running something in the 9 lb and under category. Are there any special concerns there, or are these failures pretty much confined to those that desire more than 250 hp?

For me, I want something that's reliable, gives me 230-250 hp, and will cost less than the purchase price of the car.

[IvanAtSPRacing]

I'd also like to hear about those of you running something in the 9 lb and under category. Are there any special concerns there, or are these failures pretty much confined to those that desire more than 250 hp?

For me, I want something that's reliable, gives me 230-250 hp, and will cost less than the purchase price of the car.

This would be the info I am most interested in also. The lower budget kits are the ones that make the most compromises and I am interested in others experiences.

[Structure240sx]

i blew my stock motor hitting 11-12psi with a 8:1 fmu. the wrong spring was in the wastegate. it lasted as long as it did because the spark was getting blown out. once i fixed that the next day there was smoke.

this was a combination of a poor fuel system and just some base timing retard. retard may not have taken effect since i do not believe the tps was unplugged when setting the timing

[virus77]

Ran the car on an emanage for 8,000 miles at 8-9 psi, this is on my 95 motor with 160k+ milage never been opened up, i beat on her every day. Took it up to 12-13 psi and it ran good for about 600 miles and i have a broken ring land, Most likely.

[AZhitman]

^ That's encouraging.

I'm at 125K miles, full compressionacross all four, virtually no topend wear (pulled VC and did the 2 exh cam swap), no sludge or varnish (heads shiny and silver).

Should be a good candidate for 7-9 lbs.

[BadMojo]

^ That's encouraging.

I'm at 125K miles, full compressionacross all four, virtually no topend wear (pulled VC and did the 2 exh cam swap), no sludge or varnish (heads shiny and silver).

Should be a good candidate for 7-9 lbs.

Much like Greg, I'm still toying with the idea of a low power (relatively) set-up. This survey will be very helpful.

Is it generally common for people to take the car to a dyno to check A/F ratios or is this one of the common links in our "blown KAT" survey?

[HolyShiznit]

I had a similar experience to Klattr. Mine was due to a JWT tune that was slightly lean from 3200-3600. Lean enough to pop 3 piston rings. Like Klattr, I now advocate NO ONE try ANYTHING unless they have a wideband present. This was at 1 bar of boost on an unopened 103k mile KA-T. My orignal set-up for .6 bar with the SAFC II ran perfect for 9 months of HARD abuse.

[AustinSilvia]

never blown up an engine but i'm really interested in whatever info people could supply about these low budget systems also. within the next few weeks (because of finals, otherwise i'd have it done in a few days) i will have my ka-t finished. right now the manifolds are off and i'm fitting the oil lines, building the exhaust, fitting a side mount intercooler, dealing with vacuum lines and the rest of what comes with slapping on a turbo...

I will be running 6 or 7 psi (or something very close), and i have a 12:1 fmu (i think it will be safe, or i hope rather). i'm not planning on taking this above 7 psi until my compression gets worse and i have the money to buy an sr. of course for the money i spent on everything i could have had an sr, but i wanted to do this because i have a strong ka and didn't feel like getting rid of a perfectly good engine.

anyway so any info/advice/anything could really help out a lot. i'm searching the forums for info. you think this fmu setup will be fine for my application? i will be using it for a daily car with mildly frequent (weekends, maybe 2 times a month or maybe not even that much) autocrossing and road racing and the like (read: lots of quick up and down shifting with lots of throttle, and lots of hard turning). my friend is running a similar setup on his del sol with no problems, but he has not so great compression, and is running ~10 psi (his clutch slips like crazy). hoping this setup will be okay for my car too. let me know what you guys think, or if anyone has blwon an engine up at this psi level with an fmu... thanks

[nissanfanatic]

I'm running a 6psi setup with a 8:1 FMU. This is on an unopened 135k engine. I try to take it easy on the engine but before I turboed it, it took some abuse. My pet-peeve was matinence. Oil changes every 2500 miles and Mobil 1 synthetic only. Compression is at 165. Runs great. Base timing is at 16 BTDC. I have 1k on it since turboing.

EDIT: This is my first real car. I got it last year as a graduation present for the beginning of my senior year. I did all of the work myself. First time turboing anything.

[virus77]

pretty much if you are going for 8-9 psi (~250whp range) on stock internals, as long as you have a good tune I wouldnt be worried, the motor can handle that no problem as a daily driver for a long time, about as long as not turboed. At 12-13 psi, even though the car will run for a while, it will start breaking rings with some abuse. If you are on a budget i recomend not going over the 250whp range, whether its 9 psi from a t3/t4 or 13 from a t28. Because when the motor busts its not gonna be low budget anymore.

[S14tat]

for the guys who blew up engines on the JWT ecu. what injectors programs did they write you for?

i'm running 555cc nismo/tomei ones. they have flowed plenty of those and they said that its true flow is 615cc's.

they are goin to write me up a program for those since its their most common program and i traded in my Sards for those Nismo/Tomei's.

also i know its hard for you guys to answer, but did you have any idea what a/f you guys are running before the engine gave out?

and what should be the a/f ratio be for 12-13 psi? and for 15-20 psi.?

i will take my car to the dyno and see my a/f with a wideband when i get every together.

thanks

[:: orion ::]

I broke one (cracked ring lands) KA running ~6psi, but I was using a "Hacked MAF" (tunes in the same way an AFC would...A/Fs were good at mid-11s...but I was still running a JWT N/A ECU tune, and getting close to 30 degrees of total timing near redline. Shifting at ~7200 didn't help, I'm sure...

Anyway, I voted for "Turbo with Injectors and AFC"...as that's the closest approximation to what I was running.

BTW - I kinda knew it would blow, I was just pushing it to see how far it could go. It was great for close to 2 weeks, then one cool night...it died when I was flogging the hell out of it. You live, you learn...

- Brian

[klattr1]

So what was "special" about your setup? MAF reading lower than actual flow? Low fuel pressure? Injectors on low side of the rated spec? Base timing advanced past 20 degrees? Or did JWT have a brain fart and sent you a wrong program the first time around?

dont know why still. every variable that they programmed the ecu based on originally was the same way on my car. fuel pressure was correct, etc.

[huguetpj]

Ross pistons, 7:1 Cartech FMU, 255lph HP Walbro. Was running just dandy @ 9PSI. Blew my engine by detonation at 19PSI (wrong SBC setting). Blew the head gasket which caused water to enter the engine oil, I did not notice and kept on racing. The water made the most damage. Rings, lands and pistons where ok, just scratched. Crank, block & bearings all scratched because of the water.

Tough engine, tough pistons I might say.

[Jeff240sx]

My first turbo build was 4 years ago. Non intercooled, stock fuel injectors, pump and regulator at 4.35psi off a full T04b. No fuel mods whatsoever. Auto transmission, too.My car ran like that for almost exactly 20,000 miles, until my RevHard manifold spit out a bolt for the wastegate and my friends and I repaired it. Apparently one of them disconnected the wastegate vacuum line, and I neglected to double check everything before the test drive. 0-18.5 psi, 1-2 shift, and then *clunk* as my car shut off and smoke billowed out the valvecover breather.I *SHATTERED* all four piston's ringlands. #4 cylinder had all three rings touching eachother at most points, as the lands were completely missing.

Then I lifted the head on my forged motor at 15psi, spewed antifreeze smoke everywhere and kicked the headgasket out from between the block and head. Funny thing is the antifreeze smoke went into the air compressor inlet of a body shop.. and I apparently ruined 12 paintjobs, as the antifreeze created runs and birds eyes in their paint.-Jeff

[IvanAtSPRacing]

Nice job Jeff.. That story made me chuckle... Not that you blew up the motor but the havoc it did at the body shop.

[driftjunke]

Well I have been through 2 motors, cracked ringlands on all, first setup was on a motor with 30k with a t3/t4 50 trim .48AR, running 7 psi, stock base timing, 370's safc2, AF's at 12, running 236 to the wheels, driving the piss out of the car, and it lasted for about a month, then cracked #4 ringland, popped the head off, and oil pan, re honed and re ringed the block, put the motor back together, swapped turbos over to the holset HX35W, very large FMIC, core was 32x12x3, 370's, MSD6 BTM 1 degree per pound, 370's safc, and 8 psi, lasted for about another month, a week for break in, and the rest just breaking it. Popped #2 ring land this time, I think it is more so my driving than the setup, bouncing off the limiter often, shifting at 7 grand, we are building a forged motor for the abuse now.

J.D.

[nissanfanatic]

^Thats not so encouraging. Actually it gave me the chills.lol I try to not drive mine so hard.

[sil80drifter]

Before I turboed my 140k SOHC, I've been beating on it really, really hard for about 40k miles, ever since I've bought it with 104k. Two weeks before I turboed the car, I swapped out the injectors (already had the SAFC II in, but didn't tune much, more for getting used to it) and put in some 460cc injectors. Apparently I overestimated how much I needed to tune them down for stock N/A driving on the low end (before 3200rpm) at high loads and low throttle (basically tuned the Low throttle map on the SAFC way too low). The car pinged/rattled hard, but since I didn't expect that to be a fuel problem, I thought it was a timing chain problem, especially since I was worried about the timing chain plastic guide crap in my oil pan (never flushed it after last TC job) to have been clogging my oil ways.

Did the TC job again, swapped oil pans, made sure everythign was clean. Pinging/rattling still present. For a week I pinged on it before I decided to try turning the fuel up (yes, some of us are slow or stubborn). That fixed it. But now when I went to actually turbo the car, it was a KA that has seen 40k miles of abuse and a WEEK of pinging. AND overheating (my thermostat started giving out that same week it started pinging, temps went to 250 a few times). I turboed it anyway. Before the car started pinging, my compression was 150/180/180/150. Two weeks after having turboed it, it started making lots of oil smoke (and not just from the old turbo), and I checked compression again. 105/150/150/95.I assume my rings/ring lands are shot. This was barely tuned motor, and I've done up to 10psi on it at times, and although it was always very rich when boosting, I guess the poor rings couldn't take much more abuse and added pressure.Not the best example, but pretty realistic as far as KA-Ts go.

I'll be rebuilding it this winter, taking a 70k block/rods/pistons, polishing/retapping the crank, new bearings, new rings, new stock headgasket, stock everything else. I want to run 250whp at most, and see how long a stocker in good condition, and well tuned, will last. Hopefully it'll outlive this rusty shell, and I'll be swapping it into a better hatch some time in the future.

I think it would be a good example because few of us turbo stock KAs that are new AND stock, like they came from the factory.

sil80

Modified by sil80drifter at 10:25 PM 12/13/2004
Modified by sil80drifter at 1:01 AM 12/14/2004

[574-240sx]

Me and my freinds have yet to blow a kat up. I have 137K stock motor, only boosted the last 2-3K. I have the SAFC2, knocked back stock timing, and monitor a/f closely with a wideband.

Friends 89 with 190K stock motor boosted for the last 12K, still good. Has blown 2 headgasket due to detonation problems. He just has a fmu and it leans out a little on pump gas.

Other friend has a 90 with 148K and the last 7K boosted, still fine. Has a 8:1 fmu and a rebic with 2 extra 440cc subinjectors. Runs rich at WOT but hasn't blown up yet. Very quick for a SOHC.

[95_240sx]

My car, with the full stand alone ended up detonating/melting the pistons couple days before the dyno. I actually burned the edges of the pistons off in 1 2 and 4. All of those, I deformed the pistons enough to get them to slam into the bottom of the head.

I have also had 2 head gaskets go. The first was just due to too much boost, I am thinking something messed up in the boost controller because I spiked over 32psi and it blew it out on intake side of #4, but it also blew coolant into the intake manifold and then into all the cylinders. Luckily I didnt lock the motor before I quickly shut it off. Currently though the car is lifting the head and getting blowby and has popped 2 radiators (found out the problem after #2). So, ARP's + Stock HG arent going to cut it, looking to get a Cometic soon.

Rick