Changing Stacks on a 60s detroit

Thank you. Well said.

 

12.7 Detroit, 171702, tuned by Leon, 14" resonator, 7" straight pipes. Yes, this is a true statement. By friday nite coming home I'm feeling rather deaf. God forbid it's a nice day out and I have the windows open
Sounds the same most of the time...sometimes I love it and sometimes I hate it lol

 

That's the only part in your text I'd disagree with, on a couple points. 1) 15-20 hp may be true for 1 lb of boost on some motors, not in this case. I can make 47 lbs of boost and certainly don't have hp numbers that high. 2) I get the best power from the boost about mid 30's in boost psi, not that I run it around at that pressure generally: however, pulling a grade I'll let it ride at 40 to maintain a gear and rpm speed.

Also on a side note: I have been told by several folks that have extensive Detroit mod. knowledge that the head gasket won't take much over 50psi in stock form. I feel that's pretty fair, realistically if you're pushing that kind of boost you aren't hauling general freight down the highway...or expecting to do it for long anyway So I'm right there with you on "who wants 60 lbs of boost".

Otherwise all good information in comparison to what I know on the subject.

 

Not saying that anyone couldn't create more boost. When i made that statement that 1 lb of boost equates to 15-20 hp, my intent is that running more boost than necessary is essentially over fueling and wasted energy. The statement was a general calculation of boost required for the hp one is able to use. For instance, 30 lb boost x 15 hp = 450 hp. It makes no sense to use more than 30 lb boost to get full power out of a typical 450 hp engine. It takes fuel to make boost, and running more boost than necessary is just wasting fuel. As you stated, you get the best power at 30 lb more or less. That would be correct in most cases with most stock engines. Running substantially higher than that is wasted energy. It is easier on an engine, not to mention more fuel efficient, if one is not throwing more than 30 lb at a typical engine (not a 800hp fire breather) to maintain speed, it would be more efficient, require less fuel, and lower EGT's by dropping a gear and keeping boost at 30 lb. If I am running 1500 rpm at 30 lb boost compared to another running 1300 at 40 lb boost, I am using less fuel to get the job done with very little difference in road speed (with the likes of a 13 spd tranny where 200-250 rpm splits are the norm). There is no need for higher boost pressures, when a typical engine is operated properly. That is how many with engines putting out 500+ hp are able to get better mpg than one would expect (some even approaching 8 mpg territory) compared to lower hp engines, and are still able to walk comfortably on hard pulls. There is a lot more to operating an engine efficiently than pressing the accelerator.

As an example, one gal I know... Jackie Wormley.. an O/O with Landstar can put down almost 600 hp to the ground from her Detroit 12.7, yet she consistently gets over 7 mpg. She knows the relationship between boost, rpm, and hp to get the most from that engine and do it efficiently. And no.... she doesn't haul light. You can find a video at Pittsburgh Power website of her discussing this.

 

Ah ok Cowpie, I understand. So each pound of boost is essentially capable of supporting 15-20 hp not that it will necessarily be produced in any given engine.

 

Bingo! I looked back at what I had written and probably didn't put it in the best words. The doctor warned me that some days I would be "in" and "out".

 

Mine said, "Wow, you're f*****" lmao
Oh well, I'm still doing alrite all things considered