How much boost can I run with 87 octane on an LS
Apr 11, 2020 | 01:51 PM
#42
Lol. The real answer is actually nonzero, but for the general intent of people who install aftermarket turbos and the ***** they have to turn to control them, staying closer to 0 is the better option. I can explain if anyone really wants to understand why.
Food for thought...my little DD Sonic is factory turbo at 9.5:1 and runs 87 octane. But there's a long reason for that
Food for thought...my little DD Sonic is factory turbo at 9.5:1 and runs 87 octane. But there's a long reason for that
Apr 11, 2020 | 02:06 PM
#43
And the SkyActiv motors are 13 and 14:1 and run 87
EcoBoosts (except the RS that I know of) are rated to run 87
but we are talking about motor tech that is dang near 30yrs old, electronics that at nearly 20yrs old and pretty archaic as far as knock detection goes
whether the answer is truly 0 or slightly above nonzero, the effort will not outweigh the gain, and gain def does not outweigh the penalty
EcoBoosts (except the RS that I know of) are rated to run 87
but we are talking about motor tech that is dang near 30yrs old, electronics that at nearly 20yrs old and pretty archaic as far as knock detection goes
whether the answer is truly 0 or slightly above nonzero, the effort will not outweigh the gain, and gain def does not outweigh the penalty
Apr 11, 2020 | 02:37 PM
#44
Lol. The real answer is actually nonzero, but for the general intent of people who install aftermarket turbos and the ***** they have to turn to control them, staying closer to 0 is the better option. I can explain if anyone really wants to understand why.
Food for thought...my little DD Sonic is factory turbo at 9.5:1 and runs 87 octane. But there's a long reason for that
Food for thought...my little DD Sonic is factory turbo at 9.5:1 and runs 87 octane. But there's a long reason for that
Apr 11, 2020 | 03:50 PM
#45
The smaller the bore diameter, the more resistant to detonation. Plus an ideal combustion chamber shape with centrally located spark plug reduce the tendency to detonate. They probably enlist the variable valve timing into some kind of anti detonation strategy. Probably other trickery, too.
Apr 12, 2020 | 09:57 AM
#47
Best watch that mouth!
You can run quite a bit of boost on an LS with 87 octane. The specific amount would depend on the modifications. But the problem is you can't do it for very long. You end up having to yank spark out which rejects excess heat the exhaust and coolant. The extra heat buildup lowers the detonation threshold even further, requiring more spark to be removed. The result is a thermal runaway scenario. Manufacturer boosted applications use much more elegant solutions to prevent thermal runaway, the most notable being high temp boost reduction. Lowering the boost allows temperature control via airflow instead of spark so thermal runaway is prevented.
So while it is possible to run boost on 87, you stand to lose more than you gain unless you have ECM integrated boost control. I can run full throttle on the old port injected Sonic for miles up a hill on 87 without issue because the ECM pulls boost back when needed. Even my current truck's boost controller will pull boost back if ECT or IAT gets too high. But most boost controllers don't. Just stick with 91 or better!
Best watch that mouth!
You can run quite a bit of boost on an LS with 87 octane. The specific amount would depend on the modifications. But the problem is you can't do it for very long. You end up having to yank spark out which rejects excess heat the exhaust and coolant. The extra heat buildup lowers the detonation threshold even further, requiring more spark to be removed. The result is a thermal runaway scenario. Manufacturer boosted applications use much more elegant solutions to prevent thermal runaway, the most notable being high temp boost reduction. Lowering the boost allows temperature control via airflow instead of spark so thermal runaway is prevented.
So while it is possible to run boost on 87, you stand to lose more than you gain unless you have ECM integrated boost control. I can run full throttle on the old port injected Sonic for miles up a hill on 87 without issue because the ECM pulls boost back when needed. Even my current truck's boost controller will pull boost back if ECT or IAT gets too high. But most boost controllers don't. Just stick with 91 or better!
Apr 12, 2020 | 03:26 PM
#48
Best watch that mouth!
You can run quite a bit of boost on an LS with 87 octane. The specific amount would depend on the modifications. But the problem is you can't do it for very long. You end up having to yank spark out which rejects excess heat the exhaust and coolant. The extra heat buildup lowers the detonation threshold even further, requiring more spark to be removed. The result is a thermal runaway scenario. Manufacturer boosted applications use much more elegant solutions to prevent thermal runaway, the most notable being high temp boost reduction. Lowering the boost allows temperature control via airflow instead of spark so thermal runaway is prevented.
So while it is possible to run boost on 87, you stand to lose more than you gain unless you have ECM integrated boost control. I can run full throttle on the old port injected Sonic for miles up a hill on 87 without issue because the ECM pulls boost back when needed. Even my current truck's boost controller will pull boost back if ECT or IAT gets too high. But most boost controllers don't. Just stick with 91 or better!
Best watch that mouth!
You can run quite a bit of boost on an LS with 87 octane. The specific amount would depend on the modifications. But the problem is you can't do it for very long. You end up having to yank spark out which rejects excess heat the exhaust and coolant. The extra heat buildup lowers the detonation threshold even further, requiring more spark to be removed. The result is a thermal runaway scenario. Manufacturer boosted applications use much more elegant solutions to prevent thermal runaway, the most notable being high temp boost reduction. Lowering the boost allows temperature control via airflow instead of spark so thermal runaway is prevented.
So while it is possible to run boost on 87, you stand to lose more than you gain unless you have ECM integrated boost control. I can run full throttle on the old port injected Sonic for miles up a hill on 87 without issue because the ECM pulls boost back when needed. Even my current truck's boost controller will pull boost back if ECT or IAT gets too high. But most boost controllers don't. Just stick with 91 or better!
Going to try going back to the old 3 port setup and see if its a solenoid issue.
Apr 14, 2020 | 05:30 PM
#49
2018 f-150 CCSB 2.7 w/ 3:73 gears and tool box in the bed (100lbs) + 36gl tank.
Been averaging 25mpg with empty freeways during this covid thing. Otherwise I’m around 22mpg.
Ford for daily, Chevy for play.