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Turboh Turboh is offline
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Default 07-25-2018, 04:49 PM

Hi MasterYous,

Great questions. I wonder myself at times about them.

I am not targeting speed per se. i just want to get a sense of how timing, boost and IAT affect the selection of the map. More boost sounds great but if timing is depressed by it, where is the optimal boost vs timing point? Lots of boost could simply blow a lot of partially used fuel right out the exhaust, yet the pressure could help acceleration. So the question is, IMO, what is the minimum boost to get maximum power for the engine, fuel, temperature in question.

RPM is a rate of revolution, which is easily converted to speed by known gear ratios and tire size. Measuring change in rpm is equivalent to measuring acceleration. To me speed it not the issue.. engine performance is. So there must be a boost pressure which creates the maximum rpm change without over pressurizing and driving timing advance to zero.

I will send you a summary of results tomorrow, once I clean them up. All I did is log data during a standard WOT run (2000-6000 rpm). That range is very linear. Boost is not.

As far as comparison of rpm/time rates to different IACs, as you said, I have no control but for when the outside temperature is hot or cold. Do enough runs and a good portion will fall into the same IAT for different boost maps.

It is good fun too. My bride knows I am out doing doing WOTs and looks for handcuffs when I walk in.


2017 340iX with M track handling package, 6 speed manual, BMS intake, and JB4 piggyback; EWG and FP wires; 93 octane; and fun with Honda S2000; Ninja Z1000.
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MasterYous MasterYous is offline
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Default 07-26-2018, 09:21 AM

Your goals are interesting, albeit different from mine. I really didn't think much about that sweet spot of boost efficiency till you mentioned it. I'm just looking for the fastest possible acceleration in the smoothest manner, and increased top speed (and for how long). In other words, the racing scenarios, I suppose.

Yes, I guess you could derive velocity from RPM + gear + tire size + carried weight + a few other variables I can't think of. I may be oversimplifying but I suspect MPH or KPH (true velocity as measured by the car) controls for all those variables.

I agree that there is probably a boost pressure which creates the "maximum X change" without timing going to 0, I guess for me, X is speed.

Thanks for the tip on observing IATs... I am going to try to observe IAT behavior as well, that is interesting...


2017 F23/M240i Convertible (B58) / 6MT / FF Wires / EWG Wires / BMS Air Intake / Stock Exhaust / BMS Meth (100%) / 93 Octane
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Default 07-26-2018, 10:59 AM

Thank you for the reply. We all have different views and can learn from each other that way.

FYI, I did complete my "optimal" evaluation. I compared map6 at 15.5, 15.0,14.5 and 13.5 at the same IAT. All flat boosts. FF does have some effect but seems to average out.


The optimal map for me is 15.5 psi. It gives the highest R/T and the best ignition advance average. Funny, you might think lower boost would do better, but that is not the case as far as R/T ratio. To me that makes a lot of sense and what I expected.

IAT is very important. I learned that too. In time I will look at minimal ethanol injection to bring the IAT down. IAT at 90F seems good. But that will be another story.


Take care.


2017 340iX with M track handling package, 6 speed manual, BMS intake, and JB4 piggyback; EWG and FP wires; 93 octane; and fun with Honda S2000; Ninja Z1000.
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MasterYous MasterYous is offline
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Default 07-26-2018, 11:11 AM

Quote:
Originally Posted by Turboh
IAT is very important. I learned that too. In time I will look at minimal ethanol injection to bring the IAT down. IAT at 90F seems good. But that will be another story.


Take care.
Your IAT findings will be very interesting to me as I try to figure out how much meth to inject to try and bring IAT down. This may also be the one time you'll hear me say that I might look forward to colder weather, also.

All of this might get blown to hell when flashes are widely available... because more octane allows you to deal much better with higher IAT and its effect on timing. What if you could fuel with 100% E85 without worrying about running too lean, because the DME (and upgraded fuel hardware) allowed you to throw as much fuel as you needed?


2017 F23/M240i Convertible (B58) / 6MT / FF Wires / EWG Wires / BMS Air Intake / Stock Exhaust / BMS Meth (100%) / 93 Octane
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Default 07-27-2018, 06:23 AM

Hi Masteryous,

I have attached a summary of my M615.5 runs and the effect of IAT change on boost, acceleration, etc.

In short acceleration will drop 7.8%.


Hope this helps...

Alex
Attached Files
File Type: xls WOT 15.5 Summary.xls (83.5 KB, 39 views)


2017 340iX with M track handling package, 6 speed manual, BMS intake, and JB4 piggyback; EWG and FP wires; 93 octane; and fun with Honda S2000; Ninja Z1000.
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Default 07-27-2018, 11:09 AM

More data for Masteryous.

Attached two wot runs at low and high iats at 15.5 flat

hope this helps.
Attached Files
File Type: xls 15.5 at high iat.xls (80.0 KB, 41 views)
File Type: xls 15.5 at low IAT.xls (78.5 KB, 41 views)


2017 340iX with M track handling package, 6 speed manual, BMS intake, and JB4 piggyback; EWG and FP wires; 93 octane; and fun with Honda S2000; Ninja Z1000.
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MasterYous MasterYous is offline
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Default 07-29-2018, 01:48 PM

thanks! Checking out all of this.


2017 F23/M240i Convertible (B58) / 6MT / FF Wires / EWG Wires / BMS Air Intake / Stock Exhaust / BMS Meth (100%) / 93 Octane
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Smile Best map for B58 - 12-21-2018, 08:11 AM

I continued many WOTs on various maps. I totally agree with previous comments on this thread and others, that boost must be balanced against timing advance, for best performance (acceleration).

IAT is very important and so WOTs must be compared again the same IAT and for each map. For performance I have found the simple ratio of rpm/time (slope) is quick and easy for seeing how the engine responds on each WOT run. Take enough of these runs for each map and you can set up an equation (slope) based on IATs for that set of runs, in excel, and then calculate the R/T for each map at the same IAT.

In short, maximum boost is not as important. Many WOTs have better acceleration at lower boost, since timing advance is much better.

Results so far are that map6 additive with 4 psi flat is best, with map 2 a close second IMHO.



2017 340iX with M track handling package, 6 speed manual, BMS intake, and JB4 piggyback; EWG and FP wires; 93 octane; and fun with Honda S2000; Ninja Z1000.
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