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Funny thing about modern turbo engines is that they don’t run a boost “setting” per se. They operate off of torque demand, meaning the ecm adjusts engine parameters to achieve the desired torque. If in any given set of conditions it needs 12 psi to achieve the torque demanded then that’s all it’s going to make. If the next day the ambient temp and altitude changes, the very same truck with the very same tune might make 16. Aftermarket tunes may or may not change this.
Exactly! Which is why tuning the tq to load/load to tq tables are so important!
Boost numbers are meaningless without coupling the information of turbo size or blower size. 20psi on stock ecoboost turbos is 1000x different than 20psi on a pair of GT35R's.
You should clarify that 20psi is 20psi no matter what the size of the turbo(s) are. Assuming you're speaking of airflow at 20psi with different sized turbos.
You should clarify that 20psi is 20psi no matter what the size of the turbo(s) are. Assuming you're speaking of airflow at 20psi with different sized turbos.
Not really....20psi at 150cfm is not like 20psi at 800cfm
Boost numbers are meaningless without coupling the information of turbo size or blower size. 20psi on stock ecoboost turbos is 1000x different than 20psi on a pair of GT35R's.
Thats pretty obvious. It seems clear to me he's asking about different factory engines with factory turbos.
Thats pretty obvious. It seems clear to me he's asking about different factory engines with factory turbos.
He doesn't specify what turbos. It does make a difference, and it shouldn't matter or be a topic of comparison anyway, between different engines and different turbos, I go back to my original post: boost pressure doesn't matter without specifics on the turbo.
20psi on a GT42R (aside from maybe blowing a stock 2.7 or 3.5) is way different from 20psi on stock turbos.
I know it's cool talking about boost numbers and everything, but once you learn they don't really matter without specifics, then a conversation is useless. whipple on 8psi is different than a big single gt35r on 8psi on the same motor, etc.
After spending so much time building fast diesels these little EcoBoost turbos are funny to me. Both of them would fit inside the billet S480 I ran in a compound set up for awhile. lol
I know Hondas a bit so i'll use a sound example. A 5858 precision turbo will make about 450 whp on 16-18 lbs of boost on a k20. A 6262 will do 450 whp at 11-12 lbs, and it'll do it with more timing.
You lower cylinder pressure when you do this. Guess how. higher exhaust flow.
With turbos more in doesn't necessarily mean more out. This is why and how you can start running into ignition timing limitations with smaller turbos being pushed way out of efficiency range.
well, the reason timing becomes an issue on high boost with smaller turbos is more because, like you said, way out of efficiency range, meaning they've become massive heat generators. The much higher BAT's fight higher timing capabilities.
a 6262 flows substantially more volume even at lower boost levels, obviously, so that's where the power comes.
Of course, larger turbine housings/wheels are not necessarily a bad thing, but it's about matching up to the motor properly for the desires. I have to figure Ford just went out and found what off-the-shelf turbos Borg Warner made would work appropriately for the ecoboost. K03's have been around for decades in various forms and while simple, are reliable and make power. But BW has been making 'em with really small turbine housings and wheels, which really kills top end. Torque falls flat up top and boost efficiency falls bigtime. Especially at higher boost.
You guys are overthinking it for the new people, 20psi is 20psi as far as pressure is concerned. Is 35psi in your truck tire the same as 35psi in a semi tire, yes. Volume is different.
I guess I shouldn't have posted, I probably confused more people than the comment was worth.
Last edited by Biglipps66; 12-20-2018 at 07:42 PM.
12-19-2018, 12:45 PM
