Does anyone have information on exactly what temperatures that the cpu (stock and tuned) starts pulling timing? I can't find an old thread that had this info. Also do only IATs and IAT2s haveanythimg to do with this or perhaps engine coolant etc as well?
What Iat temps does the cpu start pulling timing?
- Thread starter AlCaPwn
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CPRsm
Active Member
Not sure on a stock tune. Just started doing SCT. But there are tables for engine coolant also. not sure what stock is, but the base mapping to pull timing for coolant was 200 iirc.
Would anyone know how much 150 degree IAT would afffect an engine? Could it pull 20-30 HP off a KB setup at 20 psi?
CPRsm
Active Member
It could. Timing in boosted engines is critical to making power. How much it pulls depends on the tune. I have seen people take of pulling timing as early as 150. Some as late as 165
I don't know on the GT500 pcm off the top of my head, but in the Gen2 Lightning pcms it starts pulling spark at 150*. However if you have a KB @ 20psi then you must have an aftermarket tune which means it has probably been adjusted. So I would recommend calling your tuner and speaking to them. FFS
I have the KB tune. I called and they said the tune is good. It's a long story on how I got my car on the dyno from the dyno owner running behind to me trying to burn off the 93 I had left in the tank so I could dump in some 100 octane to buring off what was left in the lines and fuel rails to nearly cutting my finger off. I made four WOT pulls on the road to see how much boost I was making with the 20 pound pulley (I know that was stupid) just before I got back to the dyno shop and they had me pull right up on the rollers. I am almost certain they forgot to turn on their fan. This is a race engine shop that builds dirt track outlaw cars up in the hills. I had cudzoo rubbibg on my car to get in the back of their shop. The car spun on the rollers the first pull. On the second it made 650 rwhp SAE and 600 rwt. I have the KB Stage 3 and also have an o/r x-pipe. I was real disappointed. According to their website I should have been over 700. I feel heat soak may have taken 20-30 off my numbers. I did not know the SCT tuner would data log or I would have looked at it when I made the 3 pulls.
When I/m driving I can feel this studder every 5 seconds or so. I also notice my AF gage reflects this studder bouncing a point or two. I put my stock x-pipe back on so I can get it inspected in a few days and the studder is more pronounced. As soon as I put my o/r x-pipe back on I am going to order a Jon Lund tune from Lethal. I plan on doing a set of LT's but it may be some time before I get around to it. I want that 700 at the tire on the stock logs.
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