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Originally Posted by Denny McLain
Thanks for the information. Very informative and useful .
After getting the Cobb AccessPort and logging my timing, I've noticed the car pulls more timing out when it get hotter. Logged two runs with one at 184 water temp and the other after a couple of passes @ 207 degree water temps. The car pulled out 2 degrees of timing.
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There is a timing pull and you'll naturally heat soak sitting on a dyno table...
It's not necessarily water related though. Your fans trigger at 212 dgrees and shut off at 202 so this is relatively well conrolled when sitting. On the road,temps will run around 182. Most of it (timing pull) is coming from elevated IAT (intake air) temps. I monitor both IAT's and water temps full time on my Scangauge. I've also posted graphs here showing the timing pull on Corvettes when the IAT's elevate. It's much more significant with IAT's compared to water temps. It's not unusual to see IAT's go as high as 150 degrees on the 370 when heat soaking. As close to ambient is where you want to be, which is why the injen and stillen G3 work as well as they do...They pull air from outside the engine bay. The stock system does too for that matter. None of this design is very effective on a dyno as ther's just not enough air flow. This is one reason I designed the Fang vent system to get cool air to the intake. My temps run only 5-10 degrees over ambient when rolling for minimal timing changes. Stop in traffic and the IAT's elevate pretty quickly which is why the car feels sluggish in these condidtions. Mine will come back down virtually immediately as soon as cool air starts getting fed to the intakes. IAT's are genrated at the MAF just upstream of the airbox.
Cooler is always better, but a cooler Water temp won't necessarlily change the IAT problem which IMO is the area that needs to be addressed..
I've played with this on both my previous Corvette and Audi TT and designed systems and insulated airboxes to address it. Finding ways to reduce IAT's worked nicely on both as it has on my 370..