First KA-T build, question/issue

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First KA-T build, question/issue

Postby shftqikr » Wed Sep 07, 2016 6:16 pm

Hello Everyone,

I've been browsing for some time while putting my '90 ka-t together and have my first real question. I've been searching for a couple of days, but have no real answer yet on this. I am trying to find a more performance oriented head gasket for my sohc ka-t project. I have stock internals on all fresh machine work for the head and block. I am using the CXracing turbo kit which seems o be working fine at this point. I started engine up after build held rev at 2500rpm per builder's guide to seating the new rings correctly. I took the car up on the highway for a total of 2 miles, never running it hard. boost is set low at 7psi, but feels extremely smooth in operation. The issue is this, after all of 33 miles on the build, I took the car up to 5000rpm in 3rd gear 1 time, and at the end of this short pull I had a stuttering engine, and the tell tale cloud of white smoke so thick that the road behind me could not be seen. It smoked like this for the 1/2 ile ride home (watching the temp gauge the whole time), and used up all the coolant. I first checked compression which was solid a 155 on 3 cylinders, but only 120psi on #3. I added coolant, and cranked engine with no plugs in it, and of course out shot coolant from plug 3's home. I have not yet pulled it apart, but I guessing this is either a gasket blowout, or crack in head. It is held with ARP studs torqued at 70, so I don't think that is the issue. If there is a better gasket out there can someone please point me in the right direcrtion. I have already read about the mod of the dohc cometic but I'd rather have something made for this engine.
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Re: First KA-T build, question/issue

Postby SIL8D » Sun Oct 02, 2016 5:20 pm

any luck on this ?
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Re: First KA-T build, question/issue

Postby shftqikr » Tue Oct 11, 2016 8:18 pm

Yes, and no. I ended up replacing the head gasket as it was obvious that it was blown. I used a felpro replacement this time with the ARP studs. Torqued with atp lube to the needed 70ftlbs. This lasted much longer, but when I put the DSM 450cc's in with resistor, turned up to 10psi and tuned to 11.2 afr through the rpm band above 40% throttle....it lasted about 60 miles and blew again. Now on a hunt for a better head gasket option. The cars like a top at 7psi, and ran well with hard pull when I upped it to 10psi, just back to a blown gasket issue.
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Re: First KA-T build, question/issue

Postby BigLoukaT » Thu Oct 13, 2016 5:10 pm

What are you tuning with?

Does not seem normal at all to blow at 10psi. I have beaten my 200k mile sohc relentlessly for 5 years at 8psi so it seems that you have a mechanical fault with your specific engine
1990 S13
Boosted single slammer
MS DIYPNP

npx from 240sxforums wrote:i figure from my very limited knowledge about the 240 and under the hood about cars in general i would follow the sr20det trend.
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Re: First KA-T build, question/issue

Postby shftqikr » Sat Jan 14, 2017 12:34 pm

Hello again,
Sorry I let this die for awhile, life took a front seat to fun for awhile. So to catch back up, I have not yet taken it apart from the new blown gasket, but to answer your question, i am only using the SAFC 2 with an LC2WB right now. I am going to ditch that option for a Jim Wolf tuned ECU and 740cc injectors. This way I am ready from a fueling stand point to turn this thing up after I figure out why I keep blowing HG's. I agree with you about it not being normal to blow gaskets like this. This is a fresh rebuild, with all fresh timing and needed parts. So the surface is level, so not sure why this keeps blowing. I also beat the hell out of another engine I ave in my DSM, that has 150k and I run 30psi on a never opened engine with no issues. Just wondering if this is something that is seen on the KA24E engine hen using just a felpro head gasket.
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Re: First KA-T build, question/issue

Postby Crack240 » Wed Feb 01, 2017 5:09 am

I've boosted a few stock sohc engines and was able to take them up to 13 psi reliably. I don't see why your having head gasket failure. It must be an imperfection in the mating surface. Even my semi bukit motor with 22psi didn't have any head gasket failures
89 Ka24e-t
completely stock
49k miles
550cc injectors
z32maf
GSP.50 trim
38mm WG
10 psi
260wtq
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Re: First KA-T build, question/issue

Postby adamky » Sat Feb 04, 2017 12:51 pm

Do you have a way to monitor knock? And did you retard your base timing at all? You HAVE to do this with a SAFC. I've personally known of two people who blew KAs this way. You've either got too much timing causing knock, or some kind of defect in the head and/or block.
*Daily-driven* PT5857 @ 20psi, 1600cc Bosch, Nistune w/ flex fuel, etc...
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