Boost vs. Timing -- Optimal Power?
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From: Oxfordshire
Thats the Jack Sparrow school of tuning! If you get to close to that meth, you'll end up with the Keith Richards school of tuning " hey man give me a middle C"
Jack Sprat could eat no fat
His wife could eat no lean
And so betwixt the two of them
They licked the platter clean
MB
Jack Sprat could eat no fat
His wife could eat no lean
And so betwixt the two of them
They licked the platter clean
MB
I think a question still stands out, what is better, more timing OR boost.
assuming the correct amount of timing in either case.
I'll guess there is a point where the gains cross, and that the cross point is dependent on modifications to the power-plant.
iow there should be a sweet spot where timing and boost are at their relative best with each other.
and a bit more of one at the expense of the other lowers the overall.
depending on your turbo it should have psi range that suits it, beyond which it offers more psi but at less efficiency and with more heat.
timing tends to work in defense against what you have done with psi.
general thought is the more timing you can get the better. BUT, as said by others, knock and the ecu retarding gains nothing.
assuming the correct amount of timing in either case.
I'll guess there is a point where the gains cross, and that the cross point is dependent on modifications to the power-plant.
iow there should be a sweet spot where timing and boost are at their relative best with each other.
and a bit more of one at the expense of the other lowers the overall.
depending on your turbo it should have psi range that suits it, beyond which it offers more psi but at less efficiency and with more heat.
timing tends to work in defense against what you have done with psi.
general thought is the more timing you can get the better. BUT, as said by others, knock and the ecu retarding gains nothing.
Last edited by nothere; Mar 18, 2007 at 06:32 PM.
Up until the point that EGT's get out of hand because the timing has been retarded too much for the octane used, Boost is better.
Why is boost better you might ask? All other variables taken into consideration if you move more lbs. of air per minute you make more power. The limiting factor is going to be fuel. If you run 100 octane unleaded vs running 91-93, you will make more power because you are running more boost and probably some more timing. Its the boost that makes the power though. Running E85 you run inherently more timing because of the nature of the fuel (slower burning needs more advance for proper combustion). This doesnt mean you made more power becuase of timing, it just happens that E85 has some pretty cool properties in addition to the timing quirk. This has been discussed ad nasuem before, one of the threads should be a sticky so it doesnt keep getting rehashed.
Why is boost better you might ask? All other variables taken into consideration if you move more lbs. of air per minute you make more power. The limiting factor is going to be fuel. If you run 100 octane unleaded vs running 91-93, you will make more power because you are running more boost and probably some more timing. Its the boost that makes the power though. Running E85 you run inherently more timing because of the nature of the fuel (slower burning needs more advance for proper combustion). This doesnt mean you made more power becuase of timing, it just happens that E85 has some pretty cool properties in addition to the timing quirk. This has been discussed ad nasuem before, one of the threads should be a sticky so it doesnt keep getting rehashed.
Thanks guys...I was hoping that someone had found or determined the turbo spec's (flow) and figured what the ideal boost per rpm band would be for our IXs...I know folks have seen the compressor maps for the 8s, but I have yet to see one for a 9...The other reason I was wondering about the boost was that a lot of big name shops, tune for a peak of 24 psi on 93 octane on the 9....I just wonder if they know something I don't or are just being a tad more conservative...
From what I have 'heard' more like 22 psi, but the best way to determine is to play with different variables on your car I guess. At least that is what I am getting from this thread....I would have thought there was more scientific data based upon the cars, but so far I have not seen any. That said, my gut is telling me that guys like John Bradley and JCSBanks and others have determined the max based upon their tuning...
I have attached my DLL dyno graphs for your perspective (corrected and uncorrected)...Thanks Naji!
I think my WGA is lazy (opening too soon) and or my BOV as the boost comes on a bit slower than other IXs (has happened since new, with MBC, and now with modified BCS).
I think my WGA is lazy (opening too soon) and or my BOV as the boost comes on a bit slower than other IXs (has happened since new, with MBC, and now with modified BCS).
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From: Virginia Beach, Virginia
mine's an evo 8 but for comparison...
Mellon -- I have a UR cat. on the car and think that is killing the top end. I am able to hold boost nicely (19.5 psi at 7K), but timing is at least 3* lower than before due to the cat. and knock. Jestr tuned the car with a solid 11.5 AFR from 3300 - 7250. My guess is that the Cat. + timing is robbing the top end of ~10 - 15 hp and a lot of area under the curve...Just my guess as boost is really solid. Thanks
Just so you know, any of these HP/TQ calculators use a slope function that is affected by several subsequent samples.. so if you cut the run short, or include too many or too few samples after your run is over, you will get it to trend up or down slightly which will affect your HP numbers.
In his case, I think he mentioned he might have a lazy wastegate actuator. I had trouble with mine because the pre-load was too light, the tradeoff of increasing the preload is you can get boost spiking. Other possibilities are a weak DV opening slightly (I saw this on a dyno tune I had done recently)
In his case, I think he mentioned he might have a lazy wastegate actuator. I had trouble with mine because the pre-load was too light, the tradeoff of increasing the preload is you can get boost spiking. Other possibilities are a weak DV opening slightly (I saw this on a dyno tune I had done recently)
i still think these are respectable numbers for a mustang dyno (the original 315/315)...
your cat is probably hurting you a little up top... but i think MJ is correct with his post above.
cb
your cat is probably hurting you a little up top... but i think MJ is correct with his post above.
cb
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From: Virginia Beach, Virginia
Mellon -- I have a UR cat. on the car and think that is killing the top end. I am able to hold boost nicely (19.5 psi at 7K), but timing is at least 3* lower than before due to the cat. and knock. Jestr tuned the car with a solid 11.5 AFR from 3300 - 7250. My guess is that the Cat. + timing is robbing the top end of ~10 - 15 hp and a lot of area under the curve...Just my guess as boost is really solid. Thanks
No knock there?
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From: Virginia Beach, Virginia
Just so you know, any of these HP/TQ calculators use a slope function that is affected by several subsequent samples.. so if you cut the run short, or include too many or too few samples after your run is over, you will get it to trend up or down slightly which will affect your HP numbers.
In his case, I think he mentioned he might have a lazy wastegate actuator. I had trouble with mine because the pre-load was too light, the tradeoff of increasing the preload is you can get boost spiking. Other possibilities are a weak DV opening slightly (I saw this on a dyno tune I had done recently)
In his case, I think he mentioned he might have a lazy wastegate actuator. I had trouble with mine because the pre-load was too light, the tradeoff of increasing the preload is you can get boost spiking. Other possibilities are a weak DV opening slightly (I saw this on a dyno tune I had done recently)
he has an 06 car so I figured his DV would be solid... I'm running the stock evo 8 DV for what it's worth, but I'm not spiking to 26psi.. only 23-24 at the most.