Tuning to avoid head lift

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Spoolin6er
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Tuning to avoid head lift

Post by Spoolin6er »

I was recently fighting an intermittent overheating issue that turned out to be due to head lift and the head gasket showing signs of very small leaks, but in 9 places!

Engine is (finally) back together with felpro and ARP 2000 head studs tq'ed to 75 ftlb. I am running 9.5:1 CR with an EFR 6758 @15psi on pump gas. MS3 EMS, here is the timing map I was running: https://drive.google.com/file/d/0B1cQUb ... sp=sharing

I'm looking for suggestions to ensure I don't repeat history. I wasn't getting audible knock, but I suppose it was a possibility. I'm shooting for 400whp, I'd really like to avoid E85 if possible, but if that's my only option, that's all there is to it.

Thanks for any help!
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supakat
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Re: Tuning to avoid head lift

Post by supakat »

The overheating issues could be that your timing is too far retarded. @15psi with a .5:1 reduction, you should be around 17*. You have roughly around 10*. Bump up the timing across the map to meet a .5:1 reduction. Remember to start pulling timing from just before boost starts.
12.96 @ 116.36 - 2.1 60ft - 11/2011
13.1 @ 114 - 2.3 60ft - 8/2012
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Spoolin6er
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Re: Tuning to avoid head lift

Post by Spoolin6er »

It wasn't overheating from timing retard. The headgasket was allowing leakage and the head was lifting at 15psi+.

That timing map I posted was only tuned up to 220kpa, above that is retarded further in case of boost spikes. The numbers in the 220kpa break point were knock limited (audible with no headphones/knock sensor). I for sure can not increase timing further.
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supakat
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Re: Tuning to avoid head lift

Post by supakat »

Were you using stock head studs? That would explain lift at such low power. Rosado ran saturn studs to 621whp then swapped in ARP2000 and made 700+ with no lift. 220kPa is 17.1 psi. With 93 and .75:1 reduction, that puts you at 12* which is close to what you have. A little more retarded which is fine. I used a .5:1 above because I am use to doing this with corn. My bad. I just did the same with another post.

People usually lift heads when TQ is highest. Make sure your timing retard happens before the onslaught of full boost.
12.96 @ 116.36 - 2.1 60ft - 11/2011
13.1 @ 114 - 2.3 60ft - 8/2012
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Spoolin6er
Dreams of owning a 240!
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Re: Tuning to avoid head lift

Post by Spoolin6er »

I was using saturn studs. (although i did not install or tq them, but they seemed evenly tq'd when I removed them).

I agree that I should not have been lifting my head at such low boost. (although this turbo does build 15psi before 3,000rpm.) I'm thinking that detonation that I could not hear must have been my issue. Thats why I wanted to compare to other people's timing maps, to see if that is a possibility.

Also, I think i need to invest in some form of knock detection. Suggestions?
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supakat
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Re: Tuning to avoid head lift

Post by supakat »

MS3 can use the stock knock sensor. If you have a log, we can see when you start building boost to make sure the timing is retarded when this happens.
12.96 @ 116.36 - 2.1 60ft - 11/2011
13.1 @ 114 - 2.3 60ft - 8/2012
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