Originally Posted by Spooler

What is Drive pressure. Drive pressure is how much energy it takes to push the turbine wheel of the turbo. How do you measure it. You can calculate the Drive Pressure ratio by the following. EMAP/MAP. The ideal pressure for a drag engine is a 1:1 ratio but for a street car this is not very fun to drive. So where is an acceptable level. On a street car, that is normally no greater than a 1.5 to 1 ratio. So, my car last time it was tuned, the max boost was at 29psi. My car stopped making power at that level so I know the Drive Pressure ratio was at least 2 to 1. 58psi at the EMAP and 29 PSI in the intake manifold. So I had 58psi of pressure from the turbine wheel of the turbo all the way back to the cylinder head. Well, that's a big problem. That's like trying to cram 58psi of boost down the intake. The VQ won't handle it and it torches the headgasket. My head bolts were still torqued to the proper TQ. That means they did not stretch under high boost but I did get #4's fire ring. So, if you are monitoring EMAP, keep the boost no greater than a 1.5 to 1 ratio and the engine will be happy as long as your headgaskets and headbolts can handle the cylinder pressure.