Ford Scorpio Forum - Print Page


    
      
        Ford Scorpio Forum
        (https://www.fordscorpio.co.uk/cgi-bin/yabb/YaBB.pl)
      

        General >> Give/Need advice to/from others >> Surprising rolling road results!
        
(Message started by: cossieguy on Dec 14^th, 2006, 11:06am)

Title: Surprising rolling road results!
Post by cossieguy on Dec 14^th, 2006, 11:06am

Well had to endure the torture of someone revving the guts out of my Cossie, the results are now in:
204.3 BHP @ 5400 rpm @148MPH!
226.7 LBFT @3177 rpm

My question know is what would be the BHP(And speed) if the engine was unlimited? on the graph the power is still rising sharply at 5400 rpm.

Really happy that at 10 years old she is still producing the exact same BHP as when she came off the line.
Guy.

Title: Re: Surprising rolling road results!
Post by scorpio_man on Dec 14^th, 2006, 11:32am

hi there

some results! there was a lot of talk about getting a bit more mph out of the 24v, but the 'box would have been stressed.

what did the diagnostics turn up (if anything)?

Title: Re: Surprising rolling road results!
Post by cossieguy on Dec 14^th, 2006, 11:50am

Diagnostics found nowt wrong. Emissions spot on. Only negative was i need to secure my Viper kit as it moves around a bit hence moving the MAF and its plug. Also noted that engine was mechanically noisy but i've already posted about that, sounds like a diesel on start up and still tappety when hot.

Title: Re: Surprising rolling road results!
Post by martin_rowe on Dec 14^th, 2006, 3:07pm

cracking results gromet.
not bad for a car with an auto box, i take it the figures were 'corrected' for flywheel figures.

Title: Re: Surprising rolling road results!
Post by cossieguy on Dec 14^th, 2006, 4:15pm

Yep. Bloke said he hadn't had a cossie scorp in for ages and he's got another booked in within the next week as well! Any one on here? Sally or Doug maybe?

Title: Re: Surprising rolling road results!
Post by TiberiuS on Dec 14^th, 2006, 4:32pm

Guy, the way I understand it is that a well looked after engine like yours shouldn't suffer a decrease in BHP with age unless there's a problem.

Engine revs aren't limited as far as I know, the top speed is where the engine power equals drivetrain losses and drag, you could cut 10mph plus from the top speed out on the road with wind resistance. Hence Highlander may get a higher top speed even with the shorter diff...

If you get the time I'd love to see the plot uploaded, still working on the physics for the Scorpio model, anything appreciated...

Cheers, Bruce.

Title: Re: Surprising rolling road results!
Post by cossieguy on Dec 14^th, 2006, 4:36pm

Bruce, i could be wrong but i'm positive the Cossie is limited to around the 5400 rpm mark when in 4th(O/D). if you look on the main site front page there's a picture of a cossie speedo doing 140mph @5500 rpm as well. Anyone back me up or agree with Bruce. Best i could do is take a piccie of the graph and post it, would that do Bruce?
Guy.
PS just tried to get a piccie but it's rubbish,really need to scan it but haven't got a scanner soz!

Title: Re: Surprising rolling road results!
Post by TiberiuS on Dec 14^th, 2006, 5:48pm

Cheers Guy, would be handy but no probs if you can't. Any ideas what the uncorrected value was at the wheels? The sim uses torque@wheel so just putting the max engine torque value in gives you about 10% too much power.

The way I see it is that the top speed was around 135-137mph because at those revs the engine torque is on a decreasing slant and they balance at about 5100rpm. Hence the 2.3 can manage about 125-130 (if you was very lucky ;)) yet the cossie can manage 10 more even with the taller diff...

Also, the speedo reads over the real speed, so 134 or so might come out as 140 or more on the speedo.

Getting into anorak mode, if I put the 24v torque curve/autobox ratios into Racer, with the 3.64 diff the tops is 135mph, with the 4.27 it rises to 144mph, no limiter. The Chap who developed Racer also does a commercial version so it's pretty accurate. The shorter diff really opens the cosworth up it seems.

That's my take on it but if anybody can go more into it, I'm curious ;)

Regards, Bruce.

Title: Re: Surprising rolling road results!
Post by cossieguy on Dec 14^th, 2006, 6:02pm

Bruce, will have to bow to your greater knowledge on this one, but a few points that you might be able to explain:
The speed registered was 148mph, I assume this was the roller speed? If so no speedo error occured, I understand the fact the car wasn't moving hence no drag but if that was the speed of the rollers as driven by the car then even if you take 10 mph off for drag etc then it equates to 138 mph at 5400 rpm, what's stopping tha car using the extra 800ish revs? I might be missing something here so help me out ???
Guy.
PS Just had a think: If the 148mph was the speed of the rollers being driven by the car then the diff/gearbox/engine will do 148mph, in reality on the road it will be less. So the only thing stopping the car going faster is the fact that the revs will not rise above 5400. Make sense?

Title: Re: Surprising rolling road results!
Post by Paul B on Dec 14^th, 2006, 6:43pm

Tell you what Guy... I'd be well chuffed to get those results.

As you say, from a standard car, to get the same figures quoted by Ford... thats pretty good I'd say.

Oh, and I'm jealous. I want a go now :)

Title: Re: Surprising rolling road results!
Post by TiberiuS on Dec 14^th, 2006, 6:44pm

Guy, I'm curious too mate. Mabye somebody with more knowledge will be able to explain more but the way I see it is that any engine will have a decrease in torque at a certain rpm (like although an engine may be able to free-rev up to 7000rpm, it won't develop any useable power at that speed, the Cosworth develops max torque at 4250rpm, it tails off above this). The top speed of most cars is where the engine torque@rpm equals the combined drag/drivetrain resistance, so if you drove your car up a hill the top speed might only be 120mph but going down a shallow hill you might get it upto 150mph plus. Normally it's only cars capable of very high speeds which get fitted with limiters, my 4.0 hasn't got one (145-150mph tops, like your cossie) but the later Super V8 XJR (375bhp) did have, set at 155mph...

Your car is geared to be economical at motorway speeds and return good economy rather than hit 150mph, hence you have a tall diff fitted and at the mid 130's on a flat road the engine can't provide any more torque to make it go any faster (why do you need more than 136mph lol?). But with highlander's mod, when his engine hits the same speed, it's still a few rpm lower in the power band (hence slightly more power) and can go a few mph higher until it too is in balance with drag and friction etc...

Was the 148mph on the readout of from the dash?

Blimey, what a rant :D. I'm very interested in all this, if someone can enlighten us it would help me a lot with this bleedin' model ;)

Regards, Bruce.

Title: Re: Surprising rolling road results!
Post by Highlander on Dec 14^th, 2006, 6:48pm

on 12/14/06 at 17:48:34, TiberiuS wrote:

with the 3.64 diff the tops is 135mph, with the 4.27 it rises to 144mph, no limiter. The shorter diff really opens the cosworth up it seems.

It does!! Yeeehaaaaaa ;D

Title: Re: Surprising rolling road results!
Post by taliban on Dec 14^th, 2006, 6:55pm

you also need to take into account airflow into the air filter (i take it no blowers were used?), if the engine is at full revs but in a staionary position the air flow into the air intake will be much lower than it should be, this will be especially so if the cossie airbox is pressurized with a constant flow velocity, this typically adds between .3 up to .9 bar of pressure at the top end of the scale which in turn adds mph.
also what is the mileage of the cossie? a new engine is always slightly down on power as it needs to bed in. i dont know about cars, but sportsbikes typically return their best power figures between 13 and 20 thousand miles.

Title: Re: Surprising rolling road results!
Post by cossieguy on Dec 14^th, 2006, 7:03pm

Bruce the 148mph was on the readout/printout so i assume it was the measured speed of the rollers. Just looked at the printout and the torque was peaking at 226.7lb/ft @ 3177 rpm and plateaued till
4400 rpm where it dropped off to 198lb/ft at 4800rpm at this point it plateaued again till the 5400 rpm point. So at the crucial 5400 rpm point the bhp was rising sharply and torque had levelled off (But wasn't dropping).
Guy.

Title: Re: Surprising rolling road results!
Post by TiberiuS on Dec 14^th, 2006, 7:19pm

Guy, this is the one I was looking at, from the main site:

http://www.fordscorpio.co.uk/images/pow24v.jpg

If the torque levelled at 5400rpm surely you wouldn't get any more mph out of it unless it increased sharply again. Speed on the road would decrease by a few mph, if you'd taken the wheels off the ground completely you'd be able to get it to rev to the redline in 4th, probably over 150 on the speedo. Then the limiter would cut in, stopping the engine going over 6000 or so rpm.

Just be happy and enjoy your 204 horses, who else do you know who privately owns over 200 horses? :D. The general opinion seems to be that if you have a good engine in the first place and look after it, you shouldn't get a decrease in power with any reasonable mileage, my XJ12 had 128k on the clock but low for a Jag of that age, idled and ran as smooth and powerful as any mint low miler could.

Regards, Bruce ;).

Title: Re: Surprising rolling road results!
Post by cossieguy on Dec 14^th, 2006, 7:43pm

I know your right about just being happy ;)
The graph above looks the same as mine for BHP however i've got alot more torque (306 NM as opposed to 280NM)and mine doesn't fall off as dramatically, this might be down to the Viper induction kit I don't know?

Out of interest then to improve top end speed and overall acceleration are "we" saying that torque improvements are more important than BHP increases?
Is everyones (Mine included) obsession with bhp gains misguided and really should we be looking at improvements/mods that give the best torque improvements?
If so what are the best things to do to get that?
Guy.

Title: Re: Surprising rolling road results!
Post by TiberiuS on Dec 14^th, 2006, 8:37pm

Well, someone please correct me if I'm wrong but as far as I know, bhp is a product of torque and rpm. Look at the pic below, it's a program which you can use to make torque curves, the torque plot is in red and the faint grey one is horsepower calculated from the torque, the torque is a steady 1nm from 0-7000rpm but the hp goes from 0,0 right upto a peak at 7000rpm. That's why the torque can start tailing off but the bhp still rise because the engine is spinning that much faster, less power per rpm but more rpms...

http://i94.photobucket.com/albums/l89/TiberiuS1250/Standardcurve.jpg

And then there is the plot I made for the Cosworth in the same program, the horsepower is calculated by the program from the input torque, no bhp input from me. It closely matches the Ford one too.

http://i94.photobucket.com/albums/l89/TiberiuS1250/Cosworthcurve.jpg

You can have an engine with massive peak bhp at skyhigh revs but no low end spread of power so it'll be useless on the road unless you thrash it to the high rpms all the time. then you get engines (like diesels) with masses of low end torque but which can't reach the rpm's high enough to get a good peak bhp.

I figure the one to ask would be howie ;)

Regards, Bruce.

Title: Re: Surprising rolling road results!
Post by bootiful-scorpios on Dec 14^th, 2006, 8:55pm

on 12/14/06 at 16:15:23, cossieguy wrote:

Yep. Bloke said he hadn't had a cossie scorp in for ages and he's got another booked in within the next week as well! Any one on here? Sally or Doug maybe?

no not me guy. bet you were chuffed with that result .

Title: Re: Surprising rolling road results!
Post by cossieguy on Dec 14^th, 2006, 9:17pm

Certainly was pleased. Though I must admit that i'm a bit confused now! Just showing my lack of knowledge :-[
We move to Telford in 3 weeks, so evrything is a bit hectic with that and Xmas ;) Hope your all well.
Guy.

Title: Re: Surprising rolling road results!
Post by bootiful-scorpios on Dec 14^th, 2006, 9:31pm

:o you are moving that soon guy its come round so quick.
we are all well apart from some git last night >:(nicked our chrome dust caps again ! and not only that they decided to give the poor scorp a load of nice scratches (not) >:( wondering if it should be an insurance claim or will scorp get wrote off ? and having one side fully resprayed would prob allways look diffrent in diffrent light ? sally

Title: Re: Surprising rolling road results!
Post by howiedintheplace on Dec 15^th, 2006, 3:34pm

Yes torque & horse power are related to each other.

Torque is the actual force of the engine, what pushes you back in the seat etc.
Horse power is the engines ability to do work over time.

So if you have a engine that makes 400lbs of torque at 3000rpm but only 200lbs at 5000rpm it will have a lower horse power figure than a engine that makes 200lbs of torque at 3000rpm & 250lbs at 5000rpm.

The first engine actually creates 150lbs more power/thrust/force, whatever but hp wise is less than the 2nd engine.

HP is a maths equation based on torque & revs not a measure of force.

Road cars need torque, race cars need HP both should be treated differently as they are but are relative to each other ;)

Hey where is the graph then ;D
& did he do the run in 3rd gear as he should of????
148mph sounds too fast ;)

Title: Re: Surprising rolling road results!
Post by taliban on Dec 15^th, 2006, 7:09pm

or, as someone once explained it to me;

imagine you're hammering a post into the ground, the torque is the size/weight of the hammer, the bhp is the amount of times you hit it....

Title: Re: Surprising rolling road results!
Post by TiberiuS on Dec 15^th, 2006, 8:10pm

Ok, so I can understand a thing or 2 about torque and bhp etc.

But I am a little confuzed too...

On the road, what is better about having masses of top end bhp than low end torque?

I know all the stuff about diesels being handicapped because they have a low rev range and suffer from turbo lag etc etc but torque is torque, is bhp just touted around as a measure of how high in the rev range an engine can sustain torque output or what?

An answer would be nice, my brain is just about to baloon its radiator...

Regards, Bruce.

Title: Re: Surprising rolling road results!
Post by howiedintheplace on Dec 15^th, 2006, 11:35pm

Mate to fully understand it you need to add gearing into the equation assuming your in identical cars except for the engine.

On the road do you really want to race about doing 5000rpm + to use the HP of your engine. (more torque higher in the rev range)
Think how long the engine would last, petrol consumption, funny looks etc etc

Now think of the gearing. Gearing can increase force or decrease it, so if you have a engine that is high reving & makes force high in the revs the gearing does not have to be high (i.e less than 1:1)
If the engine makes most of it's force low down the revs you have to change the gearing to suit so the engine has to make more force to drive the car at the same speed. (gear less than 1:1)

Now you have a engine that actually makes more force than another but at lower revs ending up less powerful by the time the force gets to the wheels.

That's why on the track, where engine wear, fuel, noise etc etc don't matter much the engines are tuned that torque is high in the rev range.

But on a road car the lower the torque the better as it reduces fuel, engine wear, noise etc etc.

A good road car is not usally that good at the track & a good track car is usally almost undrivable on the road ;D

i.e My 2.9 12V TT uses custom made 3.14:1 diffs & a 0.73 top gear.
The car makes more actual power than a STD engine is capable of by the time it hits 1500rpm, with the custom gearing it can do 35mpg on a run which makes it better on fuel than a STD engine yet it has super car performance ;)

Of course if a floor it then I can actually watch the petrol gauge go down ;D

Title: Re: Surprising rolling road results!
Post by howiedintheplace on Dec 15^th, 2006, 11:42pm

P.S
HP is mis-understood by most people.
It is not a true figure of how much welly a engine has.
All it means is it makes alot of torque high in the rev range.

A true figure is torque but as I hope you can now see now HP plays it's part too ;D