Quote:
Originally Posted by Knifeedge2k1
Ok there's a lot to unpack here. Firstly I want to say I thought you were talking about purely ICE output, if you're referring to ICE + Hybrid Drive output, then sure you're probably easily be making 320hp at the crank easily (though probably not 370). If it's ICE only then it's doubtful if you have no additional modifications (the stock catalytic converter and OPF if you have it are quite restrictive).
You won't be able to tell without a dyno if what you care about is the actual BHP/WHP. This is ultimately a stupid game to play as which dyno, conditions, how it accounts of drivetrain losses to back out the crank horsepower. HP/Dyno charts between individuals are never comparable, they should be viewed as tools to help you tune/setup YOUR car in YOUR specific application, not as something that's comparable between individuals thousands of miles away from one another under different conditions. Dyno charts ... even from SAME dyno manufacturer ... are not SAT scores .... it's more like comparing your grades in english class (comparing within your class with the same teacher is "ok" but comparing between schools or districts is questionable).
If what you actually care about is how fast it is in the real world, dragy or actual dragstrip numbers from the same day/place are comparable and if you want to look at it from a more engine centric perspective what really matters is the entire shape of the power curve with a focus on the part of the curve you'll use ...i.e if shifting at 7000rpm redline drops you to 5000 rpm in the next gear, and you're an absolute driving god, really only the 5000-7000rpm "matter" .... assuming the power curve didn't fall off the side of a cliff .... which CAN happen
Ultimately what you "feel" are G-forces.
None of the stuff above are surprises to you but I think it's just important to reiterate the importance of the real world info/measurements over "random math and figures provided on the internet".... Even if you get on a dyno and it shows you're putting down *calculated* 380 brake horsepower .... does it matter if the guy next to you who only puts down 300 BHP is 0.2s faster in the 1/4 mile ?
Now for the thinking/logic which you've kinda missed on (to be fair, you're in the same boat as 95% of people on the forums/internet who do this, but you have the right attitude)
Firstly, take the BM3/MHD numbers with a grain of salt. In the real world things don't work like they do in a simulation or a model. Your car can respond tremendously well to a tune and your friend's car which is otherwise identical might not. It's important to know that the figures that BM3 provides are at best an average expectation and at worst extremely cherry picked figures. Also, is the % increase quoted the % increase at a given RPM associated with peak power in run 1 or run 2 ? is it the percentage increase of peak power ? is it the maximum percentage increase of power at ANY part of the curve ?
My 520i which has the B48B20B motor (mechanically identical to the 30i) struggles to make more than 300bhp on a random all wheel dyno ... I have 98RON fuel and I experience pretty severe timing retardation on full throttle, even a full can of Torco octane booster still results in intermittent timing retardation. Should I be upset at BM3 for this ? Maybe when stock my motor wasn't putting out the 184hp claimed. Ultimately what do I care more about ? The number on a graph ... or maximizing what I can do with my platform (for performance/reliability) as it exists sitting in my garage ? If you chase after numbers on a screen, two things will happen... 1) you WILL manage to achieve that number because these things are easily manipulated and 2) you'll lose sight of having fun with the thing because you will probably end up making dumb decisions which prioritize the number on the screen as opposed to something more real like reliability, turbo lag, etc.
Secondly, you also need to understand that electric motors also have a power curve just like the ICE motor. Yes electric motors tend to have a very flat power curve (relatively speaking) but it isn't a constant output. It would be VERY "handwavy" to simply just add the max power output of the electric motor to your peak power on the ICE and say combined power = A+B. The real world just doesn't work this way. To be fair to you, you WERE conservative in your estimate by taking 60 something (~50% peak electric power) + estimated ICE BHP but there's the underlying assumption that the electric motor is actually helping when the engine is operating in it's max load, max throttle/boost, high rpm state (which isn't neccesarily a reasonable assumption for lite-hybrids)
Thirdly, just forget about "adding torques". While it's actually "ok" to do in this instance because the electric motor is placed before the gearing in the transmission (taking the place of the torque converter), in most scenarios of hybrid drive the motors are situated after gearing which makes the concept of "adding torques" completely retarded. On top of all this, torque as a "performance paramater" also means basically nothing, all you care about is the shape of the power curve, torque at the engine is multipled by gearing. Saying an engine make 300ft-lbs of torque at the engine is quite useless because what matters is WHERE you're making the torque, 300ft-lbs of torque at 1000 rpm is extremely impressive (.... because that's the equivalent of 1500hp) whereas 300ft-lbs of torque at 5000rpm is a "meh" 290hp.
Fourth, I'm nitpicking here as you're actually doing well by comparing with the 540i conceptually but you're also making a LOT of hand wavy assumptions.
*weight: no one knows the weight of literally any car, there's massive variance between individual examples and manufacturer quoted weights often times are inconsistent even with themselves, ultimately you don't know the weight of your car unless you put it on some scales, how much does my G30 520i weigh ? i've seen numbers as low as 1500 kg and some as high as 1800 kg depending on the source... I have literally zero idea.
*power/weight: you're relying on a figure of questionable accuracy (weight) to predict/extrapolate an unknown quantity (power) based on your realized acceleration figures compared to some numbers you found online presumably (absolutely inapproriate to be doing this) AND you're using the worst acceleration metric (0-60mph) as it's literally the MOST manipulated number both in terms of how it's calculated (with or without rollout) as well as it's succeptibility to conditions (prep'd surface ? launch control ? brake boosting ? etc.)
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Whoa......ok first off thank you so much for unpacking all of that for me. I truly appreciate you helping me understand how all of this works. I'm going to keep this somewhere safe for future reference
I legitimately did not know that dynos, tuning software power gain numbers, 0-60 times, weight-based metrics, and general information on the internet could be unreliable. I also had no idea you shouldn't really be adding torques.
. Thanks for clearing that up as well.
I should mention that I do have upgraded coil packs from Dinan (idk what they do but they look cooler), a FTP charge and intake pipe, and a "hot" air intake from Burger Motorsports. I don't have a upgraded downpipe yet (though working towards getting an AA one possibly within the next year).
And yes, I do want to chase the numbers, but I also don't want to chase the numbers. I'm just looking for my car to have plenty of power in normal driving, but I can also hoon around if need be and actually use 100% of its power without too much to worry about, such as losing complete control. My car pulls hard enough as is, and I don't really need it making more than what it is making currently...although an extra 20-30hp wouldnt hurt.. I'm happy with it
I feel like I'm doing you a disservice by not going over every single point you covered in your reply to mine, but I can assure you I read over everything, and I now have a much better understanding of what to do and what not to do when it comes to the large and undeniably vast world of tuning.
I definitely know who to come to the next time I have questions
Thanks agaaaain