STi8

...on the rolling road.

If I have a car that is supposed to produce 340/340 am I hoping for too much if I expect it to produce more than 320/320?

Neilo

its likely yes, it can make a big difference....my car certainly doesnt like the hotter weather.

Varboy

yes it does, but I don't know how much by

pslewis

A hot day wipes out £1000's spent on Engine Performance measures!!!

Good value then!!

Har Har

Pete

Chelspeed

It's easy with normally aspirated:

PV=mRT

Where P is pressure, V is volume, m is a constant, R is something else (forget what but not important) and T is absolute temperature.

So on a 0 degC winters day T is 273k, on a very warm summers day temp is 30 degC so T is 303k. So for a given pressure increasing T from 273 to 303 will mean V falls by 273/303 = 0.9009, in other words you get 10% less air in which means 10% less power. A reputable dyno will measure air temp and baro pressure on the day and correct the dyno output to a standard set of conditions. If his standard conditions are 15degC he'll knock 5% of power of a car tested at 0 degC and add 5% onto a car tested at 30 degC.

But on a turbo the air density outside the car is 10% less but that just means the turbo pumps a bit harder before the wastegate kicks in. So you get the same volume of air in but it's been pumped more. More pumping means more heat in the air and it's that which limits power. The ECU limits power because the inlet air charge is too hot, I think it retards the ignition because warm air is more prone to det. How much it does this depends on the correction map in the ECU which is down to the original mapper.

So hard to answer your question unless someone with the same car has had it rolling roaded at 15 degC and on a warm day.

With the PPP whenver it's tested it comes out around 280bhp and prodrive say this is due to the above effect and that when it's developed with proper cold air it makes 301bhp. So around 20bhp sounds quite feasible.

pslewis

But aren't Rolling Roads simply for those who have no real friends??

Bunch of geeky anoraks relieved of a few ££££££ to get a useless graph print-out whilst all the time feeling like having lots of similar 'mates'

Sad, very sad

Pete

Varboy

I'm sure you've dreamed of taking your blue invalid carriage down to the rolling road at some point Pete

pslewis

I have had those sorts of nightmares, yes.

There I am stood with a bunch of saddo geeks talking about CockLinks and Oil Change Procedures, playing with their ******* when their car goes on the RR.

IT WAS HORRIBLE, really HORRIBLE!!!

Pete

scooby_matt

Didn't they have anything to say about you playing with their *******?

Varboy

Pete, you have some weird dreams, must be the sweeties they give you at the nursing home

~DrEaM~

~DrEaM~

my scoob with 310/300 does feel abit tired when its a Hot day...

the difference between 15C and 28C is alot...!!!

pslewis

Ah, but, the real question ....... do you get more 'activity' on your CockLinks??

Pete

hoskib

iTrader: (1)

pete, on a hot day like today do you think i should use my intercooler waterspray alot more than usual?

i can really feel the difference when i use it, would you know how much more BHP i'm producing?

cw42

iTrader: (1)

Doesn't "do" rolling roads, but has a post count of 17000 +! Who's sad now pete?

Anyway, I can answer your question regards rolling roads and whether the weather does effect your cars performance.

MY03 STI, K&N PANEL FILTER, 3 PORT BOOST SOLENOID, 3" MILLTEK EXHAUST (with sports cat downpipe) TEK 3 REMAP AT POWERSTATION IN JANUARY.

FEBRUARY ROLLING ROAD AT PROSPORT: 350BHP/343LBFT
JUNE ROLLING ROAD AT PROSPORT: 312BHP/302LBFT

Nothing has changed on the car between the 2 dates, so it's all down to the weather. Mine was the first to run in June too, at around 9am. It ran 3 times, with this last run, after an ecu reset, being the best. Pete explained, and showed me later on the diagnostic, that the mulitplier was down. (he did explain it very well, but soon went over my head )

My car doesn't feel that much slower though, certainly not in day to day driving. However, today, up in Yorkshire, it did feel slower on the way back on the motorway.
It's all relative though, as, at the end of the day, as the weather gets colder, the car gets more powerful

STI JASE

HAD MY STI ON THE TRACK YESTERDAY, IT WAS 27 DEGREES AND I GOT THE WORST TRACK TIMES THIS YEAR

SO HEAT DOES MAKE A DIFFERENCE

CHEERS JASE

P.S. HI TO EVERBODY OUT THERE ,

STi8

So should the tuning companies advertise "It's 340/340 but only when the temperature's below 15ºC" ?

theotherphil

Unless like Prodrive, they quote the warm weather figures?

alloy

Not as much as a **** driver

jasonius

iTrader: (1)

It would seem that Prodrive quote the 'best' figures, just like everyone else..!

Chelspeed: Good explination..!

Pete, keep taking the Worthers..!

pslewis

I would recommend carrying at least 100Litres of water ....... thats 100kg - or, another fat passenger.

The BHP may go up, but you need that extra power just to carry the lard **** water!!

Pete

New_scooby_04

iTrader: (4)

Subjectively - because I don't have any figures- mine does feel more "flat" under certain conditions, especially driving about town. At Motorway speeds with the bonnet scoop directing gale force cold air into the intercooler, it's not really noticable though......Not surprising I guess!!!

I'm not an engineer (unlike Pete) but my understanding is:

Cold dense air = better combustion = more power
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And less kn(c)ocklink activity :

Ns04

pslewis

"Turbochargers compress incoming air, causing it to become heated (see the universal gas equation).

Since hot air is less dense than cooler air at the same pressure, the total charge delivered to the cylinders is higher than non-compressed air, but still less than it could be.

By cooling the charge after compression, even more charge can be delivered, increasing power. Additionally, intercoolers help to increase the total amount of boost possible without causing engine knocking"

So, hot ambient air = less cooling can take place therefore lower charge delivered = less power.

Hotter air could induce engine knocking - so, a cocklink could be argued for on a HOT day But, not very convincingly - as you would just adjust it until the RED light never showed!

Pete

ex-webby

Of course...... the higher ambient temps can have an effect on power produced.

My car produces virtually the same boost profile regardless of atmos conditions. I was driving the Spec C on Friday getting things ready for next weeks Time Attack and even though the inlet temps were 30deg's, the car didnt feel much different tbh. When I got home, I even plugged in Delta Dash and the multiplier was still at 16.

Heaven forbid Pete..... a tuned car as reliable (if not more reliable) than a standard car!!!!

Regards,
Shaun.

New_scooby_04

iTrader: (4)

Mine is on "super **** max setting" Pete and it's staying that way!!!

Ns04

pslewis

WRONG!!!

Subaru would produce their cars with power outputs of 400BHP if tuned cars were as reliable as standard cars ........... if they were actually MORE reliable, then Subaru would make HUGE amounts of money from selling such cars.

No warranty issues, big power deliveries, no break-downs, EVO KILLERS!!

So, in short, SUBARU agree with me - a modified/tuned car is - by definition - going to break down more often than a standard car as supplied by Subaru!!

Pete ...... backed up by Subaru Multi Million £££££ Corporation and 100's of TOP Auto Engineers .... the voice of reason!

ex-webby

Pete,

Mitsubishi NEVER MANUFACTURED a 400bhp car off the prduction line.... 3rd party companies did that with backing from the UK importers and distributors..... but it came with a full warranty. Subaru didnt produce a 305bhp car for the EU, but Prodrive did with the full backing of a warranty with IM. So your point is???????

As per usual you are speaking out of your dump valve!! No change their then!

Tuned cars CAN BE just as reliable as a boggo standard manufactured cars.... and it don't matter which way you roll the dice, Prodrive and other developers have been doing this for years.

Your voice of reason is blinkered by the fact that you are factually incorrect most of the time!

You maybe hear to readdress the consensus..... but I am hear to readdress YOU!

Regards,
Shaun.

pslewis

Would that be HERE or HEAR

FACT is that a modified/tuned car is NOT as reliable as a standard one - stands up to any logical argument!!

Now, if you want to talk the language of fairy, fairy land then SN is just the place to get away with it

I, however, speak for the reasoned, seasoned, mature soul who knows his onions

Pete

cw42

iTrader: (1)

How typical that you start to pickup on peoples grammer when you're losing the debate Mr.Lewis What a grade a tosser you are

ex-webby

Pete,

Sorry.... we have got it all wrong and your the man!

More unfounded dribble from the Pslewis camp.

Regards,
Shaun.