Went on the rollers today

[Ceptik]

First time ever on the rollers and first time for the Supra i think too! Ive had her about a month now (should post some pics really) and have kept the engine completely standard.

I went with my old chums from uk-mkivs.net (golfs) and went on at the end. I was chuffed to say the least!

 

Its completey standard (engine-wise) and pulled a hefty 337.3bhp @ 5949rpm (107mph) and 390.1lbft @ 3830rpm. I was expecting around 260ish. Is it commonly known for standard j-spec supras to dyno at this rate?

 

The rollers were acurate too as they were tested against other well known locations.

[Jurgen-Jm-Imports]

flywheel figures right that pretty decent

[Jake]

The BHP is believable but that torque figure is frankly impossible for a standard Supra.

You say "standard engine wise" but is it decatted or what?

[hadyn]

Yeah the torque should be around the 330 mark if the figure is correct

[Bobbeh]

390 ft/lbs! Haha where did you take it?

[Ceptik]

Its still got both cats on it and standard exhaust. I'll post up a pic of the graph tomorrow cos i can scan it in at work. Does seem high doesn't it?!

[Kopite]

Torques well off i think too!

[Ceptik]

390 ft/lbs! Haha where did you take it?

 

It was at Engine Advantages in Witham, just past Chelmsford, Essex. Need 3 people in it to keep the rear wheels from spinning.

[Bobbeh]

Sounds like you need to go to a dyno center meant for cars over 200bhp m8.

[Ceptik]

Maybe. But saying that, they work on Skylines and cosworths a lot. Had a rather nice R33 in there too

[Jake]

Does seem high doesn't it?!

yeah, impossibly high. It's a sound business stategy by a rolling road company though, folks won't take their car to places that give lower figures.

[Homer]

The torque figure isn't really realistic unless you have a fully decatted car with ALL associated mods.

 

I had a calculated flywheel torque of 390ib/ft and 429bhp with my current mods.

 

If the torque is incorrect then as far as I know you can bin the bhp and most other results they gave you... rolling roads only measure torque so if they can't get that right then all results will be wrong.

[Bobbeh]

You shouldnt need anyone sitting in your boot if they've got it on the rollers correctly.

 

Take it to THOR or someone with a hub dyno, or a rolling road that can support large power cars like G-Force in Aylesbury, otherwise people will just pour scorn on your figures.

 

Do you have engine mods? As the flywheel sounds about 15bhp high for a stock engine, and the torque figure is way out.

[Homer]

It was at Engine Advantages in Witham, just past Chelmsford, Essex. Need 3 people in it to keep the rear wheels from spinning.

 

If they need people in the car to get it to grip then they have a shite rolling road! Go somewhere decent mate!

 

EDIT: Bobbeh beat me to it!

[Ceptik]

Everything under the bonnet is bog standard. I also recorded 220bhp at the wheels.

 

I dont know. This was my first time and first car of this spec so i had no idea what she'd be pushing out.

 

Bit upset now

[Bobbeh]

220 at the wheels is NOT 337hp.

 

Thats more like.. 270bhp.

 

What are you , auto or manual? if its auto that figure will be higher. I wouldnt worry, sounds like the figures you have are all over the shop, just take it somewhere better next time.

[TimH]

Bring her down to ipswich matey.... put her on my friends rollers, you will get a good reading from him (LPS) pm me if you are interested

[Jake]

If an auto Supra loses 25% through the drivetrain then 220bhp at the wheels = 293.3333 BHP at the flywheel.

(293.3333 *75% = 220)

 

293bhp is a very respectable figure for a std J-spec Supra. Besides, any rolling road figure is pretty much bullshit, it just shows what the RR operator wants it to.

[Class One]

220bhp at the wheels?

 

Did you have your aircon on??

[slick]

If an auto Supra loses 25% through the drivetrain then 220bhp at the wheels = 293.3333 BHP at the flywheel.

(293.3333 *75% = 220)

 

293bhp is a very respectable figure for a std J-spec Supra. Besides, any rolling road figure is pretty much bullshit, it just shows what the RR operator wants it to.

 

 

I thought a rolling road reads the torque at the wheels and then calculates/estimates the power back at the flywheel. It doesn't get the fly estimate and then work out the real wheels figure surely? Thats going about it back to front. Correct me if I'm missing something obvious.

 

This being the case it would be get the figure of 220bhp at the wheels and then calculate based on this reading, so if your saying 25% (which I think is a little high TBH as much as it suits me to believe it ) it would be 220 + 25% (55) = 275 bhp

 

Both figures look way out, as already said you'd be best to just ignore that data completely

[Ceptik]

So ive basically paid £30 for nothing? All the other readings were acurate though. What gives?

[JohnA]

220 was adjusted up to 337 eh?

 

50% fluff to account for transmission losses etc....gee, these guys are good...

 

I bet the VW people will go back soon, it never hurts to keep the punters happy.

[Jake]

I thought a rolling road reads the torque at the wheels and then calculates/estimates the power back at the flywheel.

That's correct

It doesn't get the fly estimate and then work out the real wheels figure surely? Thats going about it back to front. Correct me if I'm missing something obvious.

The only thing you're missing is that I didn't say any of that.

This being the case it would be get the figure of 220bhp at the wheels and then calculate based on this reading, so if your saying 25% (which I think is a little high TBH as much as it suits me to believe it ) it would be 220 + 25% (55) = 275 bhp

I only used 25% as an example because it's about the highest drivetrain loss figure anyone ever uses.

 

Look at it like this : if you lose 10% from a quid you have £0.90p

but if you add 10% on to £0.90p you only have £0.99p

 

In your example : 220 + 25% (55) = 275 bhp

you are only allowing 20% loss from the flywheel figure, not 25%.

(275fwhp * 0.80 = 220 rwhp)

[Ian C]

Aren't percentages fun This is why airflow mapping is

 

-Ian

[slick]

That's correct The only thing you're missing is that I didn't say any of that.

I

Look at it like this : if you lose 10% from a quid you have £0.90p

but if you add 10% on to £0.90p you only have £0.99p

 

In your example : 220 + 25% (55) = 275 bhp

you are only allowing 20% loss from the flywheel figure, not 25%.

(275fwhp * 0.80 = 220 rwhp)

 

Sorry your still getting it wrong Jake: 220 + 25% is definately 275 I'm afraid.

 

You have to start with the figure the rollers get first, WHEELS.

They don't know the Flywheel figure untill after its done its calculations/estimates.

 

Why you keep starting the calculation with the figure they get last after the calculation is done is beyond me.

 

I know how percentages work both adding and subtracting them thanks, but thats not the issue.... where your going wrong is starting with the end figure and trying to work back using a simple percentage when it doesn't work like that unfortunately. Adding and subtracting VAT anyone?

 

It would go something like this:

 

(220 read from the rollers)

'Right what shall we bung on top, ok 25% will do'

(220 + 25% = 275)

275 at flywheel, £30 thanks very much... cya

 

 

They don't know the end Flywheel figure untill after they've factored in a 'loss' percentage or calculation, so how can you start the calculation with it as you have done there (293.3333 *75% = 220)

Think about it and you'll realise what I mean m8, you should be starting with the 220. Hope that helps

 

 

In your example : 220 + 25% (55) = 275 bhp

you are only allowing 20% loss from the flywheel figure, not 25%.

(275fwhp * 0.80 = 220 rwhp)

 

No again, in MY example of 220 +25% I am allowing just that.. 25%.

In YOUR version of my example (275fwhp * 0.80 = 220) you are again making the mistake of starting with the end figure and therefore throwing the percentage out. Deducting 25% from 275 is totally different to adding 25% to 220, as you pointed out in your £1.00p example even though you still don't seem to get it in this case.