Yo all ..

Have a WRX MY04 with PPP which I love....

In this hot weather it seems gutless compared with the cooler weather. Is that simply because the intercooler can not do its job as well. Is it a feature of the scoob engine, or do I have to start looking closer to home (e.g. somethings wrong with mine?)

cheers

Mark

 

Search on Heat Soak

 

All turbo cars are affected by high ambient temperatures, because the inlet air temp is higher, meaning the air is less dense, the turbo has to work harder to compress this air and produce boost. Because the air is worked harder, it leaves the turbo hotter, so the intercooler has to do more work, yet it has less dense/cool air to exchange this hotter charge air into. So turbo cars suffer a double whammy with regards to performance compared to a NA engine.

What you will also notice is that when you are stationary for a while, the first few hundred yards after you set off the car feels less performant. This is because the PPP engine mapping limits boost until the inlet temperature in the air filter drops below 30 degrees, in standing traffic this can be as high as 70 degrees on a hot day.

It takes a few hundred yards for the ram air to bring the inlet temps down. The reason the engine is mapped this way is to reduce the chances of engine det occuring due to high charge temps.

 

Daz and John..

Thanks both - understand this now. At least I do not need to go to the garage. Having had the car for a few weeks, and a couple of weeks ago with cooler weather it was ...fab......, can not wait until a cold frosty winter morning ....!!

(not that I am wishing summer away of course !!!

Mark

 

So how down on power do people think their cars are in the heat?

 

Went for a blast across the Moors today and noticed the Scoob seemed a little lethargic....always the same though with this sort of heat. Still we shouldn't complain should we

 

Inlet temps on mine have been hotter this weekend than at any other time in my ownership....30 degrees minimum, 65 when stood in traffic . Really calms you down when you see them that high!

 

So, John, is it entirely safe to use foot-to-the-floor acceleration after sitting in traffic for a while, or should things be taken gently until the intercooler / intake temperatures fall. In other words, is the PPP map a fool-proof defence against detonation in hot weather or does the driver play a part too? Thanks.

 

Dont know to be honest, i would expect its been mapped on the safe side. Myself, i use a charge temp guage which is far more usefull than something that measures intake temperature, but the Impreza doesnt have a charge temp sensor fitted that the ECU can read, so thats the best you can do with the stock sensors.

I personally wouldnt nail it from the lights in very hot weather if i didnt have monitoring sesnors, but thats me being careful, most wouldnt think twice so i would expect the PPP is designed around that type of aproach.

 

Hi john! do you still have the sti5 ra? just that I have not heard much about it for a while and i seen you at the scooby shoot out in a nissan 200sx?

 

No, i sold my Impreza a few months ago, i miss a great deal.

I have taken a year out from work so had to cut back on outgoings, hence the 200SX. That stayed standard for about 5 minutes unfortunately.

I had a good run on track in a WR1 and STi8 last weekend, it was nice to find i can still drive a scoob quickly enough. Bit like riding a bike really.

 

Jiggerypokery, just in case you`re interested, when inlet temps are high after standing, driving with a little boost will reduce temps faster than driving with no boost

 

I've removed the blanking plates from under my bonnet vents for the summer to allow the heat to escape more easily. I'll re-fit them when the weather gets worse. It seems to work well as you can feel the heat escaping when the car is idling and even more so when the rad fans kick in.

 

how about the under engine tray - does this not help by trapping hot air beneath the engine ?? Would it be worth removing during summer - refitting during winter ?? Just a thought (I wait to be shot down in flames)

 

Funnily, I didn't have a tray fitted to mine when I bought it. I've never seen the need to fit one as I only use my scoob on the road anyway.

 

What about wrapping or sticking some heat reflecting material (foil like) on the air filter box? I changed the filter the other day for an STI panel filter and I had a hard time grabbing the top of the box. It was really hot because of the two hoses which are attached above it. This can't be good for the inlet air temp...Perhaps some insulating material between the box and hoses would help. Any ideas?

 

I've heard Bob Rawle talking about removing the undertray to reduce temps, and if it's good enough for him...

 

Wouldn't removing the undertray result in a cracked turbo if you hit some water? I thought that was it's purpose. Please correct if I'm wrong.

 

You'd have to go through a pretty large puddle to get water up to turbo height!

 

V interesting thread for a newish scoob owner like me . Also explains why I didn't see one Scoob in Gran Canaria over the last two weeks. 42 degrees during the day and 38 degrees at night ..... how much power would you expect to loose in these weather conditions ??

Stiks

 

10-15bhp without trying.

 

as much as that btk ??

Blimey explains the lack of power lately

 

BigGuy,

Interesting yes. I wonder if you did wrap the inlet pipe and airbox with insulating material what differences it would make to the temps.

Anyone else done anything similar here ?

 

This guy had the same idea...
http://forums.sidc.co.uk/messageview...threadid=20846







Everyone see the pics ok?

 

Well I think I'll try the same. It definitely can't make it worse!

 

also on a ppp sti if the intake temps go above 40c it lowers the power to save the engine doing any damage to itself.

 

So, is the inlet temp sensor, inside the unit which houses the maf ?

Is so, what about putting some heat reflective material around the inlet pipe ? as well as the airbox..