[fuseryder]

so I looked at the website and I'm a bit confused with the charts they posted, my car (MY18 430I RWD) has a factory rated HP of 248 however they say measured 288 and with the piggyback going all the way to 325hp, is this possible? or is this all sales talk? I mean $900 and I can get over 300hp?

[rjd_F30]

All crank numbers not wheel, hence why they seem so high. BMW uses crank numbers for marketing as do almost all manufacturers, but Dinan is one of the few aftermarket companies that does the same. We don't know what drivetrain loss percentage they're using either so their ratings are to be taken with a grain of salt. That said, those numbers seem believable, though slightly high, but I guess not out of the range of possibility.

[fuseryder]

is this normal practice for manufacturers to use crank HP? I'm really considering getting the dinan tune while waiting in BM3.

[enemigo13]

Originally Posted by fuseryder

is this normal practice for manufacturers to use crank HP? I'm really considering getting the dinan tune while waiting in BM3.

lol which planet you're from? no manufacturer declares how much power is down to the wheels as it would be different for e.g. 4wd and 2wd models with the same engine and nobody is interested about it. Every manufacturer on planet called Earth specifies how much HP(kw)/NM(lbft) engine does itself without any transmissions, wheels etc.

[rjd_F30]

Originally Posted by enemigo13

lol which planet you're from? no manufacturer declares how much power is down to the wheels as it would be different for e.g. 4wd and 2wd models with the same engine and nobody is interested about it. Every manufacturer on planet called Earth specifies how much HP(kw)/NM(lbft) engine does itself without any transmissions, wheels etc.

What he said ^

It's certainly the standard for manufacturers, but not for aftermarket companies. Almost all aftermarket companies use whp as thats really all that matters.

[fuseryder]

Originally Posted by rjdnyy224

What he said ^

It's certainly the standard for manufacturers, but not for aftermarket companies. Almost all aftermarket companies use whp as thats really all that matters.

so we are clear, BMW List HP as 248 but dinan says it is measured at 288, which theoretically means dinan is measuring the engine itself and BMW is measuring at the wheels or else this became more confusing.

[rjd_F30]

Originally Posted by fuseryder

so we are clear, BMW List HP as 248 but dinan says it is measured at 288, which theoretically means dinan is measuring the engine itself and BMW is measuring at the wheels or else this became more confusing.

No.

BMW lists 248 at the crank (crank meaning engine horsepower). Dinan lists 288 at the crank. This means that BMW originally underrated the engine.

The way that Dinan got this 288 figure was by measuring the wheel horsepower on a dyno, and then using a formula to translate it to crank horsepower. They do this because crank numbers are bigger than wheel numbers and are thus better for marketing, however, this is not the standard for aftermarket companies, as almost every other aftermarket company will list wheel horsepower, as that is much more telling and is also a direct measurement. Engine horsepower can also be a direct measurement on an engine dyno (where the engine is removed from the car), but aftermarket companies don't typically have engine dynos, and I suspect Dinan doesn't either.

In short: BMW measures and lists 248 crank horsepower, which is underrated. Dinan measures wheel horsepower and then translates it to crank horsepower, and that's how they got 288.

OEMs use crank horsepower, aftermarket companies use wheel horsepower (except for Dinan).

[fuseryder]

Originally Posted by rjdnyy224

No.

BMW lists 248 at the crank (crank meaning engine horsepower). Dinan lists 288 at the crank. This means that BMW originally underrated the engine.

The way that Dinan got this 288 figure was by measuring the wheel horsepower on a dyno, and then using a formula to translate it to crank horsepower. They do this because crank numbers are bigger than wheel numbers and are thus better for marketing, however, this is not the standard for aftermarket companies, as almost every other aftermarket company will list wheel horsepower, as that is much more telling and is also a direct measurement. Engine horsepower can also be a direct measurement on an engine dyno (where the engine is removed from the car), but aftermarket companies don't typically have engine dynos, and I suspect Dinan doesn't either.

In short: BMW measures and lists 248 crank horsepower, which is underrated. Dinan measures wheel horsepower and then translates it to crank horsepower, and that's how they got 288.

OEMs use crank horsepower, aftermarket companies use wheel horsepower (except for Dinan).

perfect explaination, thank you

[N420i]

The official BMW figures might be underrated, but they sure as heck aren't underrated by 40+hp...

[enemigo13]

yes yes, dynojet whp that's really all that matters )) just don't forget to minus 10-15% from dynojet whp numbers

Originally Posted by rjdnyy224

What he said ^

It's certainly the standard for manufacturers, but not for aftermarket companies. Almost all aftermarket companies use whp as thats really all that matters.

[rjd_F30]

Originally Posted by N420i

The official BMW figures might be underrated, but they sure as heck aren't underrated by 40+hp...

Its not out of the realm of possibility

[N420i]

My stock 420i put down 192 crank bhp and the stage 1 flash raised that to 272hp.
On the same day, on the same dyno, a stock 330i made 256bhp, and 310bhp with a Stage1 flash. Considering I smoked a stock 330i no problem on the street on a controlled pull from second gear up to the rev limiter in third (the flash also means quite q bit more torque on the 20i than a stock 30i) I tend to believe those numbers.
On another dyno a couple of years ago my same stock 420i made 194bhp to the crank, so the figures are consistent.

All pulls on 95octane european, so 91 American.

So yeah it's not out the realm of possibility but I don't think that's quite what's happening here. I think Dinan's dyno is pretty optimistic.

[rjd_F30]

Originally Posted by N420i

My stock 420i put down 192 crank bhp and the stage 1 flash raised that to 272hp.
On the same day, on the same dyno, a stock 330i made 256bhp, and 310bhp with a Stage1 flash. Considering I smoked a stock 330i no problem on the street on a controlled pull from second gear up to the rev limiter in third (the flash also means quite q bit more torque on the 20i than a stock 30i) I tend to believe those numbers.
On another dyno a couple of years ago my same stock 420i made 194bhp to the crank, so the figures are consistent.

All pulls on 95octane european, so 91 American.

So yeah it's not out the realm of possibility but I don't think that's quite what's happening here. I think Dinan's dyno is pretty optimistic.

The numbers you're quoting are crank numbers, but you say they're being measured on a dyno. What drivetrain loss percentage did you use? What wheel numbers did it put down? RWD or AWD?

[enemigo13]

all engines in the world are underrated if you would listen to dynojet guys (well maybe except e92 m3 which usually give 390-395PS in stock form instead of 420 advertised). let's take e.g. N20 2.8i. on usual dynojet it will give ~233whp in stock form, dynojet guys will add 15% "drivertrain loss" and they get crank 268 SAE hp or crank 272PS, while manufacturer declares 245PS/240SAE hp/180kw. so, it's 27PS or 11% more than specified, everybody will scream how underrated this engine is. Really? Do you know that in some EU countries police has mobile dynos (not dynojet of course ))) and if car is suspected to have more power, they will measure it and you get 30eur fine per every 1 extra kw (there is some toleration, car can give few kw more than specified, usually up to 10kw). Also, if power would be that higher compared to advertised - every insurance company could start legal process against manufacturer and would win it for sure. they calculate risk of insured person for 180kw car while actually it is 200kw? The fact is that average stock N20 gives ~250 _CRANK_ hp or 183kw on correct dyno, ~280-290hp after good stage1 tune, that's it. dynojet numbers are probably ok for checking delta - stock vs tuned, otherwise their numbers for sure are not whp, it's their invented horsepower unit which is actually between crank hp and real whp. General rule is to add 5% to dynojet "whp" and you get approx _crank_ hp of the engine.

Originally Posted by N420i

The official BMW figures might be underrated, but they sure as heck aren't underrated by 40+hp...

[N420i]

Originally Posted by rjdnyy224

The numbers you're quoting are crank numbers, but you say they're being measured on a dyno. What drivetrain loss percentage did you use? What wheel numbers did it put down? RWD or AWD?

At least in most dynos in Europe, there isn't a generic 15% loss applied to every pull, it is actually measured by the roller spindown with the transmission in neutral. They measure the WHP at the wheels, and they they measure how much energy is taken out of the dyno to spin the wheels, diff and tranny on the way down. Afterwards the losses number is added to the WHP. If anything the losses will be lower than the actual number because the drivetrain isn't loaded and so the friction will be slightly lower, giving a higher final crank BHP number. But it's nowhere near as high as the "Wheel HP" that dynojet is measuring.

The "wheel HP" Dynojets are measuring is awfully, AWFULLY close to the crank HP numbers that the dynos over here are returning for the same cars in the same state of tune.

[rjd_F30]

Originally Posted by N420i

At least in most dynos in Europe, there isn't a generic 15% loss applied to every pull, it is actually measured by the roller spindown with the transmission in neutral. They measure the WHP at the wheels, and they they measure how much energy is taken out of the dyno to spin the wheels, diff and tranny on the way down. Afterwards the losses number is added to the WHP. If anything the losses will be lower than the actual number because the drivetrain isn't loaded and so the friction will be slightly lower, giving a higher final crank BHP number. But it's nowhere near as high as the "Wheel HP" that dynojet is measuring.

The "wheel HP" Dynojets are measuring is awfully, AWFULLY close to the crank HP numbers that the dynos over here are returning for the same cars in the same state of tune.

Ok gotcha. That makes more sense and is definitely more accurate than adding a correction factor to get crank HP.

Also agree with your last statement. Dynos are really good for testing the improvement of a modification, and aren't the best for comparing cars on different dynos, but it is a ballpark.

[fuseryder]

I'm actually quite surprised at all the conversation this started, I assumed everyone was aware of the power differences but it appears that mostly everyone is ok with the guesstimate method when considering how much actual power you get from these piggyback tunes, I got the dinan on the way and I hope my butt Dyno makes me feel like it was worth the money.