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Message: [QUOTE="CamTom12, post: 263699, member: 2662"] This is a pretty accurate statement when dealing with proper timing. When timing advances too much you'll get spiking CPs and much lower power output. Boost has more to do with CPs than backpressure. I don't know what DCR usually runs on diesels so I'll just use SCR for an educational example here. You've got a cylinder with 18:1. Put 50psig on that and you're looking at ~1,165psi before combustion occurs. That's around a 79:1 ratio to atmospheric pressure. Say you're now putting 100psig to that same cylinder, now you're looking at ~2,065psi prior to combustion and around a 140:1 ratio to atmospheric. The cool thing about that is you now have roughly 140 more times oxygen in the cylinder than you would if you were running NA - so you can now inject a BUNCH more fuel than you could NA while still getting a good combustion event and make a BUNCH more power - which means even higher CPs during combustion. Timing plays a big factor still. Want to lower CPs? Retard your timing. You'll see a resultant power drop related to the lower CPs. The piston is now further along in it's downward motion when combustion begins and peaks. The larger and expanding container has less pressure on it's walls as the hot gases expand. Advance your timing back and you'll gain that power back as you transfer more energy to the piston due to the higher CPs. Go too far advanced and your combusting, heating, expanding cylinder fuel/air mass will fight the piston during it's travel up to TDC. That'll usually end in mechanical failure because of spiking CPs as combustion spreads, heat builds, and the air tries to expand against a shrinking container - creating very high pressure on its walls. [/QUOTE]