Hot weather and performance

Anonymous · July 17, 2003, 20:22

Did anyone else notice a slight loss of performance as the temperature went to 90+ degrees earlier this week (pretty rare in Manchester).

It was cooler today and my '2 seems to have gone back to its normal zippy self.

Is it me, or can ambient temp cause a noticable effect?

Mike

Anonymous · July 17, 2003, 20:38

Yep, it's all down to air density. Hot air tends to hold less oxygen in it, so therefore, performance suffers as there is less oxygen per volume of air going into the cylinder. The cooler the air, the more dense the oxygen content and therefore, more power. You weren't making it up. It's a real phenomenon.

That is why the Impreza STi has a water spray on it's intercooler. You spray water on to it, it acts like a radiator and removes some of the heat, the air cools down, more oxygen and hey presto, more power!!!

Ta da!

Anonymous · July 17, 2003, 20:51

You'll sometimes hear them mention this during F1 commentary. And John's given you a nice explanation why.

Anonymous · July 17, 2003, 20:53

Yes colder weather means denser colder air entering your engine, so there's more air so more fuel is added which =more power which = s:D

s:D

Anonymous · July 17, 2003, 20:55

Which = by the time i typed my reply John had already answered!!!! s:lol: :lol: s:lol:

Anonymous · July 17, 2003, 20:58

so all you need is one of those water sprayers gardners use and you well away s:roll: :roll: s:roll:

Just attach it to teh front of the car and attach a cord to the lever and thread it to the driver seat and when the weather gets hot just pull the cord LOL

I come up with the best ideas s:wink: :wink: s:wink:

Anonymous · July 17, 2003, 21:16

Buster, have you been on the strange stuff this evening? s:lol: :lol: s:lol: s:lol: :lol: s:lol: s:lol: :lol: s:lol:

markiii · July 17, 2003, 21:25

not as daft as it sounds.

Steve and I have been toying with the idea of water injection for a while. Just not sure the returns would be worth it for an na car at £200 a shot. Definately a goer ona turbo though.

Now there a thought Martin can by one and I'll dyno it on mine before he fits it.

Anonymous · July 17, 2003, 21:50

Quote from: "cstevens"Buster, have you been on the strange stuff this evening? s:lol: :lol: s:lol: s:lol: :lol: s:lol: s:lol: :lol: s:lol:

craige read markii's LOL s:lol: :lol: s:lol:

see im a natrual born geneusis s:wink: :wink: s:wink:

Anonymous · July 17, 2003, 22:43

Thanks,

Laughed a lot at Busters idea, hope all that go to the JAE have a great time (hope to be there next year).

Mike

filcee · July 18, 2003, 10:12

And what a difference it makes ...

It rained here yesterday, so the 'power boost' plus wet roads made for a bit of fun on the way home last night ... ultimately breaking traction in an uphill 2nd gear left hander. Don't know exactly how I did it, and it wasn't too dramatic - requiring only about 1/8th turn of opposite lock - but it was fun s:)

s:)

Must remember to see what happens when I switch off traction control when I get my new one s:D

s:D

Anonymous · July 18, 2003, 10:19

Quote from: "filcee"Must remember to see what happens when I switch off traction control when I get my new one s:D s:D

NO NO NO NO NO NO..... well not in the wet anyway! s:shock: :shock: s:shock: s:wink: :wink: s:wink:

Comer · July 18, 2003, 11:27

Hmmm that may explain the hesitation from my car last night. I Tried to poodle along in 3rd (or was it 2nd??) whilst in traffic doing 25 - 30mph and it felt jumpy. Never been a problem before but I have just fitted an Apexi which I've checked (as part of my rattle problem!) and it's very secure.

But then I got to a dual carriageway and instant ban speed and it seemed fine.

GSB · July 18, 2003, 11:39

Just to put some numbers on the effects of hot weather and poor induction for you:

Dyno run on my car, pre H&S install...

Temperature outside - 30degC ( hotter still in the workshop! )
Atmospheric pressure - 900mBar

(The DIN standards here for engine testing are 20degC and 1013mBar)

So with the car sat in a very hot workshop, with unusually low air pressure and with the usual dyno cell airflow over the car, (i.e. barely sufficient...) and a 20,000 mile old air filter element full of leaves and insects (should have been changed at the service, but was overlooked s:evil: :evil: s:evil: ...) I had 126 bhp at the flywheel... s:cry: :cry: s:cry:

Thankfully, with more normal weather, and a new filter, I am back to embarassing Boxter owners again... Normal Service has been resumed...

Anonymous · July 18, 2003, 21:01

I've got the aquamist water injection kit about to go on my car. This is basically what your on about as it sprays a fine mist of water into the path of the hot air,cooling it down. Not really simple to just attach it to a NA just to try it as it involves drilling into a inlet pipe and threading it for the spray nozzle, and cuttting into the injector signal wire to get a pulse signal.
Have a look here though m http://www.racetep.com/wik.html m spearco do a kit for NA cars for about £200 if anyone's tempted to try it.

Anonymous · July 22, 2003, 11:09

I've just been down to Power Station in Cheltenham for a power run. Unfortunately part of their software wasn't working so it didn't record the temperature or bar pressure. However, with the new K&N filter (which they say adds 2 bhp) it recorded 131bhp at 116mph or 6560rpm. Maximum speed 121mph at 6880 rpm. Torque was 110 lbf-ft at 80mph or 4560rpm.

All the above doesn't mean much to me but I do know that the K&N filter HAS improved performance. Don't hesitate, go for it!!!!!!

s:)

s:) s:)

s:)

Anonymous · July 22, 2003, 11:14

I probably wrong, but that sounds down a bit to me?!?

Anonymous · July 22, 2003, 11:31

Kris is right, Toyota state the BHP as 138, 127lbf-ft of torque and max speed as 131mph. I guess the first two depend on where you're measuring (flywheel or at the wheels), but even if they were measuring flywheel, surely the output at the wheels would be a lot lower?

As for the top speed, not sure why you're 10mph down... that's rather a lot.

Roger, did you get a chance to get readings with the stock filter rather than K&N? If not, then we've no real way of knowing if it boosts power or not.

Anonymous · July 22, 2003, 12:02

Kris,

Fuel octane, temperature and bar pressure can all make individual differences, which totalled could add 4 or 5 bhp. We don't know what fuel MrT was using or even whether in the UK or Japan's humidity when they achieved 138bhp.

My bhp might be down, but this is intended as a check without and then with the H&S exhaust.

Anyway numbers are un-important if the car is faster with a K&N filter and then even better with an exhaust change.

s:)

s:) s:)

s:)

Slacey · July 22, 2003, 12:15

Who did the runs for you Roger?

Anonymous · July 22, 2003, 14:08

Come on you guys, get it together s:roll: :roll: s:roll: s:roll: :roll: s:roll: s:roll: :roll: s:roll:

phil4
Using 4th gear they get to maximum speed then pop the clutch when it hits the rev limiter.
When I go back with the H&S on I hope to screw them for 2 runs (stock filter, then K&N) They say it adds 2 bhp.

slacey
Yet another IT bod who can't read s:roll: :roll: s:roll: s:roll: :roll: s:roll:
"I've just been down to Power Station in Cheltenham for a power run"
See m http://www.powerstation.org.uk/ m also shown on my previous posts.

Anonymous · July 22, 2003, 14:39

Quote from: "Roger H"Come on you guys, get it together s:roll: :roll: s:roll: s:roll: :roll: s:roll: s:roll: :roll: s:roll:

phil4
Using 4th gear they get to maximum speed then pop the clutch when it hits the rev limiter.
When I go back with the H&S on I hope to screw them for 2 runs (stock filter, then K&N) They say it adds 2 bhp..

Ooops. I know very little about how you test a car s:)

s:) At least now I know a little more.

Slacey · July 22, 2003, 14:57

Quote from: "Roger H"slacey
Yet another IT bod who can't read s:roll: :roll: s:roll: s:roll: :roll: s:roll:
"I've just been down to Power Station in Cheltenham for a power run"
See m http://www.powerstation.org.uk/ m also shown on my previous posts.

I meant who at Powerstation did the runs - if you remember from further up the thread, I asked you to say hi to Curtis while you were there! s:wink: :wink: s:wink: s:roll: :roll: s:roll:

GSB · July 22, 2003, 15:24

Quote from: "Roger H"I've just been down to Power Station in Cheltenham for a power run. Unfortunately part of their software wasn't working so it didn't record the temperature or bar pressure.

What you have then is an uncorected power reading. i.e. the dyno computer hasn't applied correction factors to compensate for losses or gains caused by ambient conditions. It would be worth you finding out what your local air conditions were at the time as it'll help when it comes to comparing later results. If the next time you go its colder, or the air pressure is higher, you'll make more power, even if you do nothing to the car...

Anonymous · July 22, 2003, 18:07

Slacey
I thought that I might be allowed to control the car whilst it was being tested, but realised that wasn't possible when it was being prepared. Rich did the run. I believe his surname is Fenton. Isn't he one of the owners?

I did remember to say "Hi" to Curtis for you,but as I don't know your real name he couldn't remember you!!! Apparantly he has worked on 15/20 Roadsters for a firm in Liverpool, I think that imports them.

Grant
Unfotunately the part of their system that records the extra information has let them down twice and they are changing the software instead of paying again to have it fixed. I didn't know this so hadn't asked for the information to put on the print-out by hand and Rich Fenton can't now remember the detail. BOLLOCKS!!!!!!!!!
Of course what you say is spot on, so I am hoping to get TWO runs out of them next time for the price of one.

phil4
I wasn't being rude. I have picked up a hell of a lot of information from you guys so nautrally thought you would have a much greater knowledge than me!!! I was only repeating what I had read on the forum.

s:)

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s:)