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  1. #51
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    right, so wheel tq is what counts is it not? thats the component that transfers the power to the ground, which is what moves the vehicle. so regardless of final drive, axel tq or anything else, those wheels are moving the rotating at xxxx rpm, with a higher (dyno tq) reading # meaning it can move said vehicle further, faster?

  2. #52
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    Click here to enlarge Originally Posted by DBFIU Click here to enlarge
    Why does that torque curve plummit like that? This turbo is supposed to be much more efficient than stock and yet it looks like torque is pulling out real hard top end even with flat boost? Someone explain.
    It looks like that because HP/TQ is not scaled the same.

  3. #53
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    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    right, so wheel tq is what counts is it not? thats the component that transfers the power to the ground, which is what moves the vehicle. so regardless of final drive, axel tq or anything else, those wheels are moving the rotating at xxxx rpm, with a higher (dyno tq) reading # meaning it can move said vehicle further, faster?
    Your wheel torque doesn't take into account the gearing multiplication, that is what I'm telling you. It isn't all that matters, part of the whole pictures. Use your wheel torque to get your crank torque and then do this:

    So how do we make a car that has a motor putting out such weak torque faster? That's when gears come in. Gears will multiply the torque by certain factors depending on their size/teeth count. Take a GS-R in first gear (3.23), when the motor spins 3.23 times, the driveshaft will turn once. And for every 4.4 turns of the driveshaft, the differential (final drive, 4.4) will turn once. That is directly connected to the axles which turn the wheels. You can simply multiply 3.23*4.4 to get an absolute gear ratio of 14.212:1. This means for every 14.212 turns of the motor the wheels will turn once. So if the motor gets to turn 14.212 times in order to only turn the wheels once, the amount of torque the motor is applying to the wheels gets multiplied that many times.

    Multiply it out, 14.212 * 110 lbs-ft = 1,563 lbs-ft of torque to the wheels. Now does that look better? Yes I think we can accelerate a car decently with that amount of torque.
    So, multiply absolute gear ratio X torque.

    Examples, BMW M3:

    E92 M3 DCT 1st gear: 4.78 x final drive 3.15 = 15.057.

    15.057 is the absolute gear ratio, multiply x torque 295 pound-feet = 4441.815 torque at the axle.

    BMW 335:

    335 manual 1st gear: 4.06 x final drive 3.08 = 12.5048

    12.5048 is absolute gear ratio, multiply x torque of 300 lb-ft = 3751.44 torque at the axle.

    In first gear, the M3 has more torque than the 335 even though the 335 has a higher torque rating. Get it?

  4. #54
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    no, its still doesnt make sense, because thats not what is actually happening. wheel tq is the last place power is transferred, so on a dyno, the axles are rotating the wheels, which are in turn moving rollers @ xxxrpm, applying more force. same as on the road, thats how its getting the higher dyno # to begin with.

    so on the actual road, same thing, a 335 IS putting down more tq that the m3, this is evident by the fact that a m3 wont move as fast, in 1st gr as the 335, hence why when a 335/m3 owner switches cars, the first thing they notice is the tq difference

    example, 1st gr, apply 25% throttle in an N54, and it puts you in your seat, repeat with the M, and its a much weaker force.

    i am failing to see how a component, thats not the last stop for power transfer means its applying more force

  5. #55
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    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    no, its still doesnt make sense, because thats not what is actually happening. wheel tq is the last place power is transferred, so on a dyno, the axles are rotating the wheels, which are in turn moving rollers @ xxxrpm, applying more force. same as on the road, thats how its getting the higher dyno # to begin with.
    Yes, it does make sense because the dyno is reading it in 1:1, not in axle torque. I've changed my final drive, dyno'd, as long as it is 1:1 it doesn't matter even though I increased the torque multiplication by going to shorter gearing. The engine torque turning those gears never changed.

    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    so on the actual road, same thing, a 335 IS putting down more tq that the m3, this is evident by the fact that a m3 wont move as fast, in 1st gr as the 335, hence why when a 335/m3 owner switches cars, the first thing they notice is the tq difference
    Uh, no, the M3 is putting down more torque hence why it accelerates much faster in 1st gear compared to the 335.

    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    example, 1st gr, apply 25% throttle in an N54, and it puts you in your seat, repeat with the M, and its a much weaker force.
    No, it isn't, and this is completely subjective. The physics, math, and actual acceleration results reflect this.

    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    i am failing to see how a component, thats not the last stop for power transfer means its applying more force
    Ever changed gears on a bike?

  6. #56
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    Isn't the ability to accelerate anything only limited and dependant upon power in our case whp, the gearbox only helps us to stay in a hp sweet spot (if geared correctly for your engine and prefered speed "zone"). A diesel has tons of tq but doesn't stand a chance against a petrol engine (with less tq but more hp), of course the gearing must be done correctly.

    This is my understanding of applied high school physics stuff like f=m*a...

  7. #57
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    Click here to enlarge Originally Posted by xbox_fan Click here to enlarge
    Isn't the ability to accelerate anything only limited and dependant upon power in our case whp
    No, there is far more to it than just whp.

  8. #58
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    does changing the gears affect the tq # put down on the dyno?

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    1 out of 1 members liked this post. Reputation: Yes | No
    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    does changing the gears affect the tq # put down on the dyno?
    Nope

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    It only affects the total hp output, torque will more or less remain the same reading in all gears.

    It makes perfect sense to me. Take a step back and look it over again LM Click here to enlarge

  11. #61
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    Click here to enlarge Originally Posted by xbox_fan Click here to enlarge
    Isn't the ability to accelerate anything only limited and dependant upon power in our case whp, the gearbox only helps us to stay in a hp sweet spot (if geared correctly for your engine and prefered speed "zone"). A diesel has tons of tq but doesn't stand a chance against a petrol engine (with less tq but more hp), of course the gearing must be done correctly.

    This is my understanding of applied high school physics stuff like f=m*a...
    This is true....to a point. When you start throwing a lot of power at a diesel, torque goes through the roof due do how diesel burns and the basic properties of a diesel engine. This is why a dodge ram with a big single turbo or compounds will put a hurting on a vette and be down in the 11s or 10s. A diesels torque never changes in all the gears...in 5th you are still making 1500ft/lbs.

    If you've ever been in one, you will notice that it keeps pressing you back in the seat harder and harder with each gear change...while a gas car feels really fast in the 1st 2nd gears, then kinda stops having any g force effect on your body

  12. #62
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    Click here to enlarge Originally Posted by Matt@Camber-Toe Click here to enlarge
    A diesels torque never changes in all the gears...in 5th you are still making 1500ft/lbs.
    What kind of gearing do they have? a 2.1 final drive? lol. They rev so low they must fly through the RPM and gears otherwise. Also, what kinda tranny do they use, what kind of parts are inside?
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  13. #63
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    Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
    What kind of gearing do they have? a 2.1 final drive? lol. They rev so low they must fly through the RPM and gears otherwise. Also, what kinda tranny do they use, what kind of parts are inside?
    I gotta go back and dig up the article where I read it. Its pretty much based around how a diesel engine runs and the amount of energy stored in diesel fuel....you can take a Cummins these days and spin it to 4 or 5000rpm and make huge torque numbers....diesel fuel also burns very slow compared to gas and this is one of the reasons why its torque curve is as flat as a table and goes to redline....it burns for almost 40-50 degrees of crank rotation..its still burning and pushing the piston down, where as a gas engine ignites right away and the resultant force kinda 'shoves' the piston down...diesel keeps constantly expanding after injection and burn which allows more force to be exerted on the piston.


    There are some great diesel shops that make some great transmissions...ATS is one, as well as Suncoast, Browns Diesel, etc. A big majority of the market runs Suncoast converters, they are some of the best in the market bar none...and yes the final drives are pretty low, most factory final drives are in the 2.8 or 3:1 range. A lot of guys who drag race run 3.80s or even 4:1......the engine revs very fast and you need a bigger RPM band to take advantage of the shorter gearing....otherwise you max out at 80mph LOL. The one downside is that the transmissions have very short lifespans if it does strictly drag racing....a lot of guys who run competitively bring 4-5 transmissions just in case...when you use a torque multiplier in 1st gear the truck is really making something like 15,000ft/lbs, and people wonder why they snap axles, output/input shafts, CV joints, etc.

    It takes a lot...a LOT to move a 5-7000lb truck down the 1/4 at 120-130 mph in the 11s.

    I always wanted to buy a diesel truck, I did a lot of reading and research on them over the past few years...as I said before Im a total gearhead so trying to learn how things work always interests me Click here to enlarge

  14. #64
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    im trying to understand it, and im not trying to be argumentative, but it still escapes me.. time to dig deeper

  15. #65
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    Diesels are amazing powerplants. They are simple and very very efficient compared to gas engines. There are 30 year old diesel engines getting 40+ mpg, look how much technology they put into gas engines to get there and only recently.

    As for power, diesels love boost, what else is there to say.
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  16. #66
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    Click here to enlarge Originally Posted by DBFIU Click here to enlarge
    Diesels are amazing powerplants. They are simple and very very efficient compared to gas engines. There are 30 year old diesel engines getting 40+ mpg, look how much technology they put into gas engines to get there and only recently.

    As for power, diesels love boost, what else is there to say.
    What else is there to say? Why the hell hasn't the USA embraced diesels? There isn't even a decent mid-size diesel truck option.

  17. #67
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    most of the bimmers in EU are diesels.
    07 335i AT - MOTIV 750 - MHD BMS E85 - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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  18. #68
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    What else is there to say? Why the hell hasn't the USA embraced diesels? There isn't even a decent mid-size diesel truck option.
    Because the liberals in america have scared the masses into thinking its dirty and unreliable. Thank chevy for trying to take a small block chevy in the 70s and trying to turn it into a diesel...they failed miserably...then you had the 300D benzes..the ones you always see huffing black smoke down the parkway...yeah they tainted it too for us.


    Not to mention the govt is corrupt with tax rebates on gasoline...diesel? Pffft

  19. #69
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    Click here to enlarge Originally Posted by Matt@Camber-Toe Click here to enlarge
    Not to mention the govt is corrupt with tax rebates on gasoline...diesel? Pffft
    So what you are saying is I should run things?

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    Here is another update!!

    Last night we went back to a DynoJet facility near us that we used back in the day. Corrected numbers often bother people because they say it isn’t accurate. Unfortunately we are at 5700ft above sea level and anything uncorrected will show VERY low numbers. Before I get into releasing the results I want to give some technical / factual data for why dynos up here read so low and why we use corrected values.

    We want to thank a handful of individuals before continuing.First and foremost you guys for following along our journey to take the n54 to a higher level of performance. We’d also like to thank our friends who have helped along the way – the guys at cp-e, Tobz Performance and Tuning, Dustin Jones, James McCotter and the dyno shops for working around our schedule.

    Back to business!! Elevation has 2 primary affects on a boosted car's performance, those are turbo efficiency and decrease in barometric pressure.

    TURBO EFFICIENCY
    Pressure ratios play a large role in how efficient a turbo can sustain airflow (power). The higher the pressure ratio, the faster the fans must spin, which requires more pressure differential across the turbine, thus more exhaust manifold back pressure and a hotter, less efficient charge temp from the increased fan speed (friction). Pressure ratio's are generally on the Y-axis of a compressor map, and as you move higher, you move away from the ideal efficiency islands. Here are 2 calculated pressure ratios to give you an idea of how altitude affects turbo performance.

    Pressure ratio = (boost + baro) / (baro).

    - 14psi at sea level: (14psi boost + 14.7psi baro) / (14.7psi baro) = 1.952
    - 14psi at 5500 ft: (14psi boost + 12psi baro) / (12psi baro) = 2.167

    That is an increase of 0.215 PR, not huge, but still significant depending on the turbo used.

    Let's look at 30psi next, and show how the difference becomes worst at higher boost levels

    - 30psi at sea level: (30psi boost + 14.7psi baro) / (14.7psi baro) = 3.041
    - 30psi at 5500 ft: (30psi boost + 12psi baro) / (12psi baro) = 3.5

    That's an increase of 0.46 PR, which is significant on most any turbo.

    This shows why a turbo must work much harder to sustain a given boost pressure at altitude.

    BARO PRESSURE DROP
    We all know that dyno correction factors aren't the most accurate for a boosted car. But we can calculate close to what the real losses are. I'll show 2 examples, but simply speaking, when running 14.7 psi of boost (same as sea level baro), and when running 29.4 psi boost.

    % performance loss = 1 - (elevation max pressure / sea level max pressure) x 100.

    Car running 14.7psi boost loss at 5500 ft:
    1- [ (14.7psig + 12psia) / (14.7psig + 14.7psia) ] = 9.2% loss due to elevation

    Car running 29.4psi boost loss at 5500ft:
    1- [ (29.4psig + 12psia) / (29.4psig +14.7psia) ] = 6.1% loss due to elevation.

    So as the boost pressure increases, the affect of elevation decreases. Said differently, when running lower boost, you’re more susceptible to barometric losses of elevation. This is why boost is so cool – and why only running 14psi as a baseline for the power we plan on making is hurting us in reference to our numbers. Had we been pushing 30psi the loss due to elevation wouldn’t affect us as much.

    In summary, there are 2 primary affects that elevation has on a boosted cars performance, and they are inversely related.

    - As boost pressure increases, the losses due to elevation are decreased. This is a good thing.
    - As boost pressure increases, the turbo efficiency at elevation becomes worse. This is a bad thing.

    But regardless, delta numbers are what matters most on any dyno!

    So the best logical solution on any car is to run as much boost as possible, on a turbo with lots of head room – enter the AR Single Turbo Kit for the BMW n54.

    SO – with this understood I will present the incredible results we were hoping for from last night’s tuning session. Last night our goal was to get the AFR leaner (we had been running very rich intentionally up to this point) and get timing how we wanted it. The next dyno session will be dedicated to turning up the boost little by little until we run out of fuel – then we’ll throw race gas or meth or both at the car – followed by our fueling upgrades which we have been actively building.

    Our baseline is a slightly modified stock twin turbo pull and that rang up 313.23whp and last night we reached 485.97whp at only 14lbs on 91 octane and the stock exhaust. This was done with a bone stock fuel system and no additional fueling or cooling from water/meth injection. Right there with very poor gas you are looking at 172.74whp. Not a bad start. Considering this turbo is efficient at over twice the boost we are running right now – it can only grow exponentially.

    So here is the chart. As in every community/platform/forum there will be people that want to bash. If you’d like to make a comment or criticize please PM me and we’ll talk. Clouding this thread with more banter (most of what has been posted as negatives is simply misunderstanding of facts – so I will help you clarify and then we can post if theres something I missed). THANKY YOU GUYS!!
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  21. #71
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  22. #72
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    well.....it seems there is a lot of potential for this thing.. i want to see what happens on the higher boost, say 18 psi, not on stock exhaust, with pumpgas and then with meth ect.. this looks like its getting good real soon

  23. #73
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    Wow, exactly what I was hoping for! Look at the torque curve finally! It spools a lot later but who gives a $#@!, look at that, beautiful!

    486WHP THROUGH STOCK EXHAUST ON 91 OCTANE RUNNING ONLY 14PSI AT 5500FT!!!

    I have some faith in the N54 head now, this is AWESOME!


    This is assuming everything posted is true. I wish they had plotted boost, but I have no reason to believe they are lying.

    The N54 is headed in the right direction. Click here to enlarge

  24. #74
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    yeah, they certainly are great numbers. i can say i was wrong when i said i didnt expect anything from AR, but this turned out to be good. i hope they can continue to tweak it and push more power out of it. 91 oct and 486 wheel is awesome. no meth too right? very impressive. what tuning did they end up with cp-e?
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  25. #75
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    Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
    what tuning did they end up with cp-e?
    Yes, CP-E is tuning and involved with the project.

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