Converting whp to Bhp

[Hussain Alzubaidi]

Hello everyone 

Recently I got my Exige s v6 tuned and got 304whp on a mustang dyno I would like to know how much is it in BHP 

Regards 

Hussain 

[Hussain Alzubaidi]

I tried to Google it but I got different results some say BHP to whp I have to minus 25% some say 20%  other say 15% I'm confused 😅

I really need some help 

Regards 

Hussain 

[andydclements]

By WHY , do you mean Wheel Horse Power?

If so, there's no "conversion" calculation that's true for all cars.  The dyno can be used to estimate the power lost through the drivetrain (they do it as part of the run), and then add that proportion to the WHP to calculate the estimated flywheel BHP. It's always an estimate, and the same car putting out the same power at the wheels could give two wildly different results for BHP estimates from different dyno machines. The flywheel BHP will be higher than the power at the wheels, (because the drag of the gearbox, differential etc doesn't generate additional motive force) but how much they'll differ depends on the car, lots of things that affect it such as the type of gears, the lubrication used, the list goes on..... 

Some dynos will be more accurate than others, as to why? Well, people want to be able to say their car has a massive power output, some do it by modifying almost every component to reduce power drains (such as @Changes has ), others do it by adding a free-flowing exhaust and going to a dyno place that gives high estimates.

[Hussain Alzubaidi]

Thanks for the reply 

A friend of mine said that I should buy a vbox sport reading so that I can get reading of the car from 0 to 100 and 200 then do modifications and do another reading but I have done some modifications such as exhaust system intake and supercharge TVS1900 Harrop 

I still feel I can get more wheel horsepower 🤔

[Mark030358]

From what I gather a tvs1900 in an Exige should make around 415hp at the flywheel. So let’s say 20% losses therefore on your BEST run your only making 360 at the flywheel. On your second run the powe is well done, maybe heatsoak. For sure it’s not 415. However as Andy said no two dynos read the same.

cheers

[Hussain Alzubaidi]

Thank you  mark for your reply 

You are absolutely right it should at least give me 332 whp (wheel horsepower) I should go back to the tuner and ask him to increase the boost or something at least the range of 330whp because I'm sure the TVS1900 can go up to 440bhp around 352whp ya?

[Mark030358]

Is it an SSC upgrade? Or a bespoke fir? If SSC then either the dyno or your car has an issue.

cheers

[Hussain Alzubaidi]

Yes it's ssc tvs1900 

I think the tuner is using mustang dyno therefore is showing less maybe 🤔

Or the tuner himself 

[BfranklynV6]

Have you tried it with the standard SSC map? 

[Jack]

Many people believe that Mustang dynos read lower than DynoJet units -- comparing RWHP numbers measured on different dynos (even the same style of dyno) and under different conditions (ambient temps, humidity, etc) is like comparing apples to oranges.  As as also been mentioned, the operator of the dyno can manipulate the numbers, typically to show greater gains from their product. As far as drivetrain loss to calculate BHP, 12-15% would probably get you close with a Lotus (it's a pretty efficient layout).  All wheel drive vehicles will show a greater drivetrain loss, more like 20-25%.  All of the numbers re: drivetrain loss you've heard are just guestimates.  

A good explanation and I believe a good read of the Mustang vs DynoJet approach to measuring RWHP:

DynoJets are inertia dynos, and have been around for years, much longer than any type of load cell dyno. Inertia dyno's work on the principle of the acceleration of a known mass over time. Their rollers are the known mass. Weighing in at over 2500lbs or so. Your car gets strapped down to the machine, and the dyno collects it's data. It is able to calculate horsepower by measuring the acceleration in rpm of the rollers in regards to RPM. This is why gearing can affect the dyno results, more on that in a bit. Now that the dyno has recorded the horsepower curve, it can take the integral of that curve and get the torque curve. Since the dyno’s power calculations are based on the acceleration of mass over time in regards to RPM, gearing is very important. Since a vehicle with a lower gear ratio can accelerate the mass to a higher speed using less engine RPM, it will show a higher horsepower number than a car with a higher gear ratio. If a car is able to accelerate the dyno’s rollers from 200rpm (roller) to 300rpm (roller)in 1500rpm (engine), then the dyno is going to record more power than a car that did that in 2000rpm (engine).

Now we go to Mustang dyno’s and other loaded dyno’s. Our Mustang MD-1100SE dyno’s rollers weigh 2560lbs. That is the actual mass of the rollers, much like the DynoJet. That’s about where all the similarities end. When we get a car on our dyno, we enter two constants for the dyno’s algorithms. One being the vehicle weight, the other being what’s called “Horsepower At 50mph”. This is a number that represents how much horsepower it takes for the vehicle to push the air to maintain 50mph. This is used as the aerodynamic force. Mustang dyno’s are also equipped with a eddy currant load cell. Think of a magnetic brake from a freight train. This magnetic brake can apply enough resistance to stall a big rig. Off one side of the eddy currant load cell, there is a cantilever with a 5volt reference load sensor (strain gage). As the rollers are spinning this load sensor is measuring the actual torque being applied. So as the rollers spin, the load sensor is measuring the force being applied, sending that information to the dyno computer, taking into account the two constants entered earlier, computing the amount of resistance needed to be applied to the rollers to load the car so that the force of the rollers resistance is as close to the force the car sees on the street. The dyno is then able to calculate the total force being applied to the rollers in torque, and then taking the derivative of that torque curve to arrive at the horsepower curve. Since torque is an actual force of nature, like gravity and electricity, it can be directly measured. Horsepower is an idea that was thought up by man, and cannot be directly measured, only calculated.

I like to state it like this. . . I start by asking how much your car weighs, lets say 3500lbs. Now you take your car and you make a make a WOT rip in your tallest non overdrive gear, how much mass is your engine working against? 3500lbs right? Now you strap your car on a DynoJet and you make a WOT in the same gear, how much mass is your engine working against? 2500lbs right? Now you strap your car on a Mustang dyno, how much mass is your engineworking against? 2500lbs. Plus the resistance being applied by the eddy current generator. We’ve seen anywhere for 470lbs of resistance to over 700lbs of resistance as measured in PAU force in the data logs. So which one is more accurate? Well they their both accurate. If a DynoJet dyno says you made 460rwhp, then you made 460rwhp. If a Mustang dyno says you made 460rwhp, you also made 460rwhp. Now which one of those numbers best represents what your car is doing when its on the street. That’s a different question.

The most important thing to remember is that a dyno is a testing tool. If the numbers keep increasing, then you’re doing the right thing. We try to look over at NET gain, instead of Peak HP numbers. A 30rwhp increase is a 30rwhp increase regardless of what dyno it is on.

Now I can address how to calculate the difference between one type of dyno and another. Simply put, you can’t. Because Mustang dyno’s have so many more variables, it’s not a simple percentage difference. We’ve had cars that made 422rwhp on our Dyno, two days later make 458rwhp on a DynoJet the next day. We’ve also had cars that made 550rwhp on our dyno, make 650+rwhp on a DynoJet a few days later at another shops Dyno Day. For instance, my 2002 Z28 with a forged internal LS6 Heads/Cam/Intake, makes 460rwhp on our dyno. I thought that was a little low, since I’ve had cam only LS6 Z06 vettes make 450rwhp. So I overlaid the dyno graphs. Guess what, the PAU force for my car was almost 200lbs more than the C5Z06 that made 450rwhp with cam only. So I entered the weight and horsepower at 50 number for a C5Z06 and did another horsepower rip with my car. The only reason I did that was to compare Apples to Apples. This time my car made 490rwhp, no other changes. Now I don’t go around saying my car made 490rwhp, I say what it actually did with the correct information entered into the computer. It made 460rwhp. Now if I ever get a chance to take it on a DynoJet (which I plan to in the spring), I have no doubts it’ll be over 500rwhp. I know this based on airflow and fuel consumption on the data logs.

But since we’re asked this question constantly we're fairly conservative, and hence tell our customers that the difference is closer to 6-7%, but as you make more power, and the more your car weighs, the difference increases as well. You must remember, Dyno's regardless of the type are tuning tools, and are in no means meant to tell people how fast their car is. Now which one is more "real world" is a totally different question. I like to explain it like this..... If you drive your car in a situation in which you have no mass and you're in a vacuum, so basically if you do intergalactic racing in space, use a DynoJet. If your car sees gravity, and has an aerodynamic coefficient, and you race on a planet called Earth, then use a Mustang Dyno

 

16 hours ago, Hussain Alzubaidi said:

Yes it's ssc tvs1900 

I think the tuner is using mustang dyno therefore is showing less maybe 🤔

Or the tuner himself 

 

[GFWilliams]

Dynos are a magic thing... 

for a layman, this is my dyno graph which shows whp and then engine PS. I’m sure someone can work out the percentage difference.

[Hussain Alzubaidi]

7 hours ago, Jack said:

Many people believe that Mustang dynos read lower than DynoJet units -- comparing RWHP numbers measured on different dynos (even the same style of dyno) and under different conditions (ambient temps, humidity, etc) is like comparing apples to oranges.  As as also been mentioned, the operator of the dyno can manipulate the numbers, typically to show greater gains from their product. As far as drivetrain loss to calculate BHP, 12-15% would probably get you close with a Lotus (it's a pretty efficient layout).  All wheel drive vehicles will show a greater drivetrain loss, more like 20-25%.  All of the numbers re: drivetrain loss you've heard are just guestimates.  

A good explanation and I believe a good read of the Mustang vs DynoJet approach to measuring RWHP:

DynoJets are inertia dynos, and have been around for years, much longer than any type of load cell dyno. Inertia dyno's work on the principle of the acceleration of a known mass over time. Their rollers are the known mass. Weighing in at over 2500lbs or so. Your car gets strapped down to the machine, and the dyno collects it's data. It is able to calculate horsepower by measuring the acceleration in rpm of the rollers in regards to RPM. This is why gearing can affect the dyno results, more on that in a bit. Now that the dyno has recorded the horsepower curve, it can take the integral of that curve and get the torque curve. Since the dyno’s power calculations are based on the acceleration of mass over time in regards to RPM, gearing is very important. Since a vehicle with a lower gear ratio can accelerate the mass to a higher speed using less engine RPM, it will show a higher horsepower number than a car with a higher gear ratio. If a car is able to accelerate the dyno’s rollers from 200rpm (roller) to 300rpm (roller)in 1500rpm (engine), then the dyno is going to record more power than a car that did that in 2000rpm (engine).

Now we go to Mustang dyno’s and other loaded dyno’s. Our Mustang MD-1100SE dyno’s rollers weigh 2560lbs. That is the actual mass of the rollers, much like the DynoJet. That’s about where all the similarities end. When we get a car on our dyno, we enter two constants for the dyno’s algorithms. One being the vehicle weight, the other being what’s called “Horsepower At 50mph”. This is a number that represents how much horsepower it takes for the vehicle to push the air to maintain 50mph. This is used as the aerodynamic force. Mustang dyno’s are also equipped with a eddy currant load cell. Think of a magnetic brake from a freight train. This magnetic brake can apply enough resistance to stall a big rig. Off one side of the eddy currant load cell, there is a cantilever with a 5volt reference load sensor (strain gage). As the rollers are spinning this load sensor is measuring the actual torque being applied. So as the rollers spin, the load sensor is measuring the force being applied, sending that information to the dyno computer, taking into account the two constants entered earlier, computing the amount of resistance needed to be applied to the rollers to load the car so that the force of the rollers resistance is as close to the force the car sees on the street. The dyno is then able to calculate the total force being applied to the rollers in torque, and then taking the derivative of that torque curve to arrive at the horsepower curve. Since torque is an actual force of nature, like gravity and electricity, it can be directly measured. Horsepower is an idea that was thought up by man, and cannot be directly measured, only calculated.

I like to state it like this. . . I start by asking how much your car weighs, lets say 3500lbs. Now you take your car and you make a make a WOT rip in your tallest non overdrive gear, how much mass is your engine working against? 3500lbs right? Now you strap your car on a DynoJet and you make a WOT in the same gear, how much mass is your engine working against? 2500lbs right? Now you strap your car on a Mustang dyno, how much mass is your engineworking against? 2500lbs. Plus the resistance being applied by the eddy current generator. We’ve seen anywhere for 470lbs of resistance to over 700lbs of resistance as measured in PAU force in the data logs. So which one is more accurate? Well they their both accurate. If a DynoJet dyno says you made 460rwhp, then you made 460rwhp. If a Mustang dyno says you made 460rwhp, you also made 460rwhp. Now which one of those numbers best represents what your car is doing when its on the street. That’s a different question.

The most important thing to remember is that a dyno is a testing tool. If the numbers keep increasing, then you’re doing the right thing. We try to look over at NET gain, instead of Peak HP numbers. A 30rwhp increase is a 30rwhp increase regardless of what dyno it is on.

Now I can address how to calculate the difference between one type of dyno and another. Simply put, you can’t. Because Mustang dyno’s have so many more variables, it’s not a simple percentage difference. We’ve had cars that made 422rwhp on our Dyno, two days later make 458rwhp on a DynoJet the next day. We’ve also had cars that made 550rwhp on our dyno, make 650+rwhp on a DynoJet a few days later at another shops Dyno Day. For instance, my 2002 Z28 with a forged internal LS6 Heads/Cam/Intake, makes 460rwhp on our dyno. I thought that was a little low, since I’ve had cam only LS6 Z06 vettes make 450rwhp. So I overlaid the dyno graphs. Guess what, the PAU force for my car was almost 200lbs more than the C5Z06 that made 450rwhp with cam only. So I entered the weight and horsepower at 50 number for a C5Z06 and did another horsepower rip with my car. The only reason I did that was to compare Apples to Apples. This time my car made 490rwhp, no other changes. Now I don’t go around saying my car made 490rwhp, I say what it actually did with the correct information entered into the computer. It made 460rwhp. Now if I ever get a chance to take it on a DynoJet (which I plan to in the spring), I have no doubts it’ll be over 500rwhp. I know this based on airflow and fuel consumption on the data logs.

But since we’re asked this question constantly we're fairly conservative, and hence tell our customers that the difference is closer to 6-7%, but as you make more power, and the more your car weighs, the difference increases as well. You must remember, Dyno's regardless of the type are tuning tools, and are in no means meant to tell people how fast their car is. Now which one is more "real world" is a totally different question. I like to explain it like this..... If you drive your car in a situation in which you have no mass and you're in a vacuum, so basically if you do intergalactic racing in space, use a DynoJet. If your car sees gravity, and has an aerodynamic coefficient, and you race on a planet called Earth, then use a Mustang Dyno

 

 

Thanks for your reply Williams 

Great information on the mustang dyno and dynojet I think it will be good to check on dynojet as well just to see what difference between them 

7 hours ago, GFWilliams said:

Dynos are a magic thing... 

for a layman, this is my dyno graph which shows whp and then engine PS. I’m sure someone can work out the percentage difference.

Nice graph and very good whp number 💪👍

[Hussain Alzubaidi]

11 hours ago, BfranklynV6 said:

Have you tried it with the standard SSC map? 

Yes I tried but not very good results for some reason maybe wether or wrong map 

[Cain-it]

Marhaba Hussain

Is the transmission manual or auto.... there'll be a difference in transmission losses.

If auto, according to this post, there are some tweaks required to get more than stock power to the wheels : https://www.lotustalk.com/forums/f170/better-ips-460660/

Even the larger SSC 1900 will heat soak over sustained use, just less so than the stock 1320 - neither have any cooling of the charge as part of the design. Considering the typical ambient temperatures in the UAE,  are you aware that there's a version of the Harrop TVS 1900 SC with integrated charge cooler? BOE aren't the only vendor to offer it, SSC, EliseRacing, Calibrated Performance  & others are options too : https://www.boefab.com/collections/evora/products/evora-chargecooler-series http://www.eliseracing.com/harrop-supercharger

The UAE has poor quality automotive fuel compared to other countries. Cars that need higher quality fuel to achieve their optimum do suffer here

HTHs

 

 

 

 

Edited October 20, 2018 by Cain-it

[Cain-it]

Oh, BTW, did you do a dyno run pre Vs post 1900 install?

Dyno's / operators / conditions vary, but the difference pre Vs post install should be a better indication of what you've gained compared to what was expected.

[Hussain Alzubaidi]

Thanks for the information 

Yes It's automatic transmission but I did run before and it gave me 245whp then I installed the kit now it gives me 304 wheel horsepower 

I think the whether is the real factor 

Maybe I should look in to ssc water intercooler kit if they can sell me only the water intercooler without the supercharger because I already bought the TVS1900 supercharger before therefore no point of buying another TVS1900 

 

[BfranklynV6]

How about water-meth? 

Would be much simpler and lighter than a charge cooler. I havnt heard of anyone trying it on these non-charge coolest exiges, which suprises me.

[Hussain Alzubaidi]

49 minutes ago, BfranklynV6 said:

How about water-meth? 

Would be much simpler and lighter than a charge cooler. I havnt heard of anyone trying it on these non-charge coolest exiges, which suprises me.

Thanks for your reply franklyn

Yes I have installed water methanol kit from aquamist hfs-4 it's  50/50 mixer and it's holding on so far. The temperature goes up to 100°c after 4 laps then I get one lap for cooling down.

I don't know wether it's safe to drive at higher temperature like 120°c or I should stick with 100°c 

[Hangar 111]

On 18/10/2018 at 16:28, Hussain Alzubaidi said:

Hello everyone 

Recently I got my Exige s v6 tuned and got 304whp on a mustang dyno I would like to know how much is it in BHP 

Regards 

Hussain 

Very clear demonstration of heatsoak right there.

Dave

[BfranklynV6]

20 hours ago, Hussain Alzubaidi said:

Thanks for your reply franklyn

Yes I have installed water methanol kit from aquamist hfs-4 it's  50/50 mixer and it's holding on so far. The temperature goes up to 100°c after 4 laps then I get one lap for cooling down.

I don't know wether it's safe to drive at higher temperature like 120°c or I should stick with 100°c 

Oh, very nice! Is it plumbed in pre or post-charger?

Did you notice it bring the intake air temps down significantly?

[Hussain Alzubaidi]

The Spray nozzle installed at the air intake before the supercharger and yes there is some reduction of temperature.

The fact is the temperature is high in August in my country but the system worked well.

I don't know at which temperature is going to reach the limit because I'm planning to increase the boost with smaller pulley. I hope  I don't snap anything 😅

[Bravo73]

7 hours ago, Hussain Alzubaidi said:

The Spray nozzle installed at the air intake before the supercharger and yes there is some reduction of temperature.

Tuners with lots of experience of SC’d 2GR engines advise against this. The bearing in the SC won’t appreciate the water & meth mixture for long. 

https://www.mr2oc.com/188-v6-mr2-forum/664993-water-injection-s-ced-2grs.html#/topics/664993

[Hussain Alzubaidi]

Thanks bravo 

Yes you are right on the water methanol injection but some time you have no choice.

I'm looking for intercooler water cooled that I can fix to the supercharger then I can remove the water methanol kit.

[Jack]

On 18/10/2018 at 08:28, Hussain Alzubaidi said:

Hello everyone 

Recently I got my Exige s v6 tuned and got 304whp on a mustang dyno I would like to know how much is it in BHP 

Regards 

Hussain 

Hussain, do you have a better/different copy of your dyno run w/o that MIN/MAX/AVG overlay.... I'd like to make sure I'm reading your A/F numbers accurately, as they correspond to RPM's.

If I am making it out correctly, it sure looks like you are running very lean......"lean is mean" until it's not.

Also, too lean (before it does catastrophic engine damage) could impact power numbers.  

[Hussain Alzubaidi]

Yes your right it is lean and I have taken the car back to the tuner to fix the lean problem, install carbon fibre intake and a smaller pulley.

Once I get the new chart I will post it in this page 👍