ka-t blew headgasket, can someone review timing map

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91boostedb20
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ka-t blew headgasket, can someone review timing map

Post by 91boostedb20 »

Well my ka-t blew the headgasket the other day. Im getting coolant in cylinder 1 and 2. I have it tuned to 10psi, engine runs strong under full boost and everywhere throughout the rpm range. My afr's in boost hold 11:1 which should be pretty safe. What I thought was weird was it happed when I turned the car off after just cruising around not even hitting any boost, out of nowhere it started pouring coolant out of the overflow tank. I did notice it runs a touch lean in the cruising area under 2500 rpm's, afr's in the mid 16:1 range. I just pulled 1 degree of timing per pound of boost from my max timing at 0 psi. Seems comparable to other ka-t timing maps I looked at. The engine has a felpro head gasket and arp head studs. The block and cylinder head was decked when I built the engine. Maybe I was getting slight detonation in the cruising range because of it being a little lean. All opinions are appreciated[img
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p00t
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Re: ka-t blew headgasket, can someone review timing map

Post by p00t »

Both times when my head gasket went it was well after the dyno. Depends on how bad it is and how long it takes for air to pile up and screw with the water pump.

I have never been able to run the low load stock timing values because it would ping/stumble when I would blip the throttle. Other people have been fine... not sure why. I think I am down around 36-38 there where you are at 46. But every setup is different.
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91boostedb20
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Re: ka-t blew headgasket, can someone review timing map

Post by 91boostedb20 »

Im thinking about pulling some timing in the cruising area for sure. Im not looking to be on the limit of knock, I'm just looking for a safe tune for an everyday car. Im probably gonna pull a point or 2 at 10psi too just to be safe.
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supakat
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Re: ka-t blew headgasket, can someone review timing map

Post by supakat »

What turbo you running, how much psi, and when full boost hits?
12.96 @ 116.36 - 2.1 60ft - 11/2011
13.1 @ 114 - 2.3 60ft - 8/2012
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91boostedb20
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Re: ka-t blew headgasket, can someone review timing map

Post by 91boostedb20 »

t3/t4 50 trim, 10psi, full boost around 3000-3500 rpm depending on what gear im in.
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supakat
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Re: ka-t blew headgasket, can someone review timing map

Post by supakat »

10psi @ 3k puts you at 16* which is good but the ramp up could be the issue with tq and causing you to blow coolant. If it is instant boost, then timing may be too advance for your boost threshold curve. Meaning that in between 170 kpa and 135 kpa, the timing may not retard enough or fast enough for your spool. This is one reason why I have map switching enabled. I can have good resolution for idle/cruise and boost. That is the only thing I can think off. If you take a 3rd gear pull log and put into Virtual Dyno, you will see where your tq curve is.
12.96 @ 116.36 - 2.1 60ft - 11/2011
13.1 @ 114 - 2.3 60ft - 8/2012
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91boostedb20
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Re: ka-t blew headgasket, can someone review timing map

Post by 91boostedb20 »

Yeah the spool up is pretty quick. I was thinking about using the dual table feature to run more resolution with the fuel and timing tables. Just thought I would start as simple as I could first you know. Once I fix the head gasket I will have to do a log and see how it is in virtual dyno. So if I kept the timing values I have in my tune now for the 135 and 170kpa section, and just add more resolution and blend in the timing values in between, then I should be pretty safe? I think the megasquirt has an interpolation feature when you add more columns in the map, I just need to find it. It seems that a 1 degree reduction per psi is conservative on these engines.
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