Question on turbo for m8 need some info

[vans]

On the ho motor a lot of people use timing key to retard the timing to save from deto correct? If u are using that key it cause u done have the fuel octane, fuel injector are max, and boost is set to high. Correct? If so turnning the boost down and run good fuel should prevent this being needed correct? I know the h.o motors are pron to deto cause of the higher compression head hence why most kits recommend it to be reworked correct? If so wouldn't u be lowering compression so u can run higher boost safe? Thus having less hp at the same boost your could run safely on the old head correct? On an h.o m8 at around 4000-8000 ft with stock injector and head u should be able to run about 8lbs of boost on 100 av correct? With the head reworked and extra injectors at the same elevation and fuel I can't see making more hp cause your lowering compression in head so you maybe able to run higher boost pressure but your not makin a lot more hp correct? Reason I am askin all this is cause if I only plan on running av gas and I know up in election means less octane needed I think that unless I am above 10000 ft even with secondary injectors I wouldn't have high enough octane to support 10 psi or better correct. Runnin in revy, mcbride Ect you run pump and max injectors at about 8 psi add secondary u would run out of octane around 2-4 psi later correct. Don't want to run race gas have no problem with avg but is it worth the extra cost to buy race gas and only gain a few psi or add a timing key which will save you motor for low elevation deto and I guess also high if the fuel can't support the boost at elevation than your running say 12 psi on gauge but cause of timing key you have the hp of say 10psi correct?

 

[gibsons]

That is a lot of quesions. I don't know much about the timing key, and correct me if I'm wrong, but I believe most turbo kits that run the pump gas on the H.O sleds run the lower compression heads, and are good from 6-10 lbs. boost for that reason you mentioned because the system can't deliver enough fuel, race gas turbos run an extra set of injectors. I was always told 6-8 lbs pump, 8-12 lbs av gas, or just run av gas all the time which is what I have been doing. You can mix race gas with pump gas, and many do, to get there octane up to the 100 mark.

 

[bgraff1]

your HP is limited by your octane and fuel delivery. they way you get that HP doesnt really matter. high comp/ low boost, low comp/higher boost, either way you will be at the same HP number in the end. i run 10-12lbs all day on straight av with a pump cut head and 2 secondary injectors.

 

[dvst8r]

...high comp/ low boost, low comp/higher boost, either way you will be at the same HP number in the end...

This actually isn't true, low compression with higher boost will make more overall horsepower, however higher compression with lower boost, will be more rideable off boost.

 

[snowbuster]

My Pg Tm8 has the timing adjusted by cutting the cylinders down, so Linderman said as long as I run good fuel (av or mixed pg/rg) the timing key isn't necessary. I have the adjustable boost, just keep it turned down on lower elevations and turn it up when you get to elevation. Usually 9lbs is the most unless up at 10000 ft. My understanding is that the duty cycle and volume of fuel the 2 stock injectors can deliver is maxed out at 8-10 lbs of boost. Any more boost you will create a lean condition regardless of octane level. Adding secondary injectors allows more fuel therefore you can push the boost right up to 18lbs or so. The octane level is critical to prevent detonation and also makes it run a lot cleaner.