Quote:
Originally Posted by SteveN
Rod Bell has built OSG RB30s at 7.5:1 for customers who wanted a reliable 700bhp on pump gas, has he not?
Granted, that dont stop the crank pulley flying off mid journey, but it stops melted pistons.
Id not go to 7.5:1 unless i was running coming on for 2bar held on pump gas tho, and the 7:1 thats been mentioned sounds like "2.5bar held, on pump gas and mild duration cams" style compression to me.
Shocked if lower comp affects boost threshold much tho, certainly not as much as big ports and lairy cams do (which also compounds any bad effects lowering comp would).
Certainly would lose some off boost power, but not actual boost threshold really, unless it was mapped for the higher compression still.
Im bored of RBs anyhow, bloody things  |
Are you attempting to have a dig? Or Am i just reading it wrong???
I'm not aware of any RB30's that we've built for customers that have been under 8:1 and I've built all of the RB30's apart from the first one in the country which Rod did at Middlehurst's years ago. Maybe it is that one you are refering to?
If you are agreeing you lose off boost power, then how can you assume you don't alter boost threshold, it's exhaust gasses which drive the turbo, and quantities of exhaust gasses are linked to how much power the engine is making.
We've run engines in near identical states of tune but with diferent CR's and the differences do exist. I am only speaking from my own experience so that others don't need to go to the time/expense of experimenting. If you have evidence to prove my thinking incorrect I would be VERY interested to hear it.