Martin2005

A question for the technically minded.

I read on here a couple of weeks ago that the PPP remap retards the boost pressure in the intake temperature, get too warm (above 40c I think).

Now this may be the answer to why my car ran so slow at Santa Pod, as I basically kept it ticking over all the time (upto 30mins waiting in the cue).

Now my question is, is there anyway to trick the sensor into not retarding the boost......

......or does anyone have any good tips as how to avoid this problem on RR days or when 1/4 mileing

Gutmann pug

If the boost is being retarded as you say then its being done for a reason? The car is therefore not ready to be bounced off the rev limiter for the next 1/4 mile?

Daniel-S

Speaking of retarded posting three times

justanotherperson

you will make your engine go pop if you try to do that,

Gutmann pug

Martin2005

It doesn't mean anything of the sort, the reason it retards is that the sensor is telling the ECU that the ambient temp is over 40c, when it isn't, it's just warm under the bonnet with no air outside air moving past the sensor.

Gutmann pug

so drive with your bonnet open then .......

Martin2005

Isn't there anyone sensible on tonight?

Gutmann pug

whats the problem ...... If the air temp is so hot around the sensor due to sitting on tick over for such a long period open the bonnet or turn the engine off and push the car along like most other people do .....

It appears to me like I am being sensible.......

silent running

Yes, and the engine is UNDER the bonnet, just the same as your intake air is, and your intake temp sensor. When you're waiting to stage at Santa Pod, your number 1 enemy, especially with a turbocharged car, is HEAT. That's why everyone who's not mucking about pushes their car a quarter of a mile in the height of summer down the staging lanes or leaves them idling with the bonnet open, only closing the bonnet when they have to.

If it's hot under your bonnet, that's what your intake air will be. Hot air into turbo = even hotter air out of turbo. An intercooler can only do so much cooling of the air, and sitting at standstill with the bonnet down and the engine running (or even if it's just been switched off) is about the most punishment you can ever give a Scooby's TMIC.

So let's break it down: every component under you bonnet is hot. The air under the bonnet is hot. The engine is drawing in hot air. The turbo, when it's boosting will add a load more heat. The intercooler is soaked with heat and can't do anything to get rid of the heat that the turbo is pumping into it. The super hot air is being pulled through into the inlet manifold and then the engine, on idle, where the ECU can just about manage to keep everything running fine by keeping the radiator fan on, plus it's not being asked to make any kind of serious power anyway.

Now you are going to ask you car to perform at its very best up the quarter mile - full boost, full throttle, not enough airflow over at least half the run, far more heat than the engine can get rid of...BANG there goes your engine.

That's why we have intake temp sensors. They do a job that you shouldn't try to get around. What you SHOULD be asking is not how can I fool the temp sensor into thinking that it's colder than it really is, but how can I actually MAKE the underbonnet area colder? How can I manage the heat under there?

I could go on for hours but I won't. People who've never been quarter miling themselves don't know the half of it that's for sure. As you've found out yourself, it's not just a case of driving in a straight line.

Hope this helps

Martin2005

Thanks for this.

I think my post may have been a bit misleading, what I was really looking for was advise as to how to get the best out of my car on quarter mile runs (I went for the first time a couple of weeks ago, and was surprised at how poorly it pulled at higher revs.

Thanks for taking the time to respond, next time I'll know!

Cheers

Gutmann pug

So perhaps my answer wasnt as stupid as you thought fella? Doubt I will get an apology for but hey such is life .....

Gary

Butty

iTrader: (2)

You could always try those great MAF inlet temp tricking devices on Ebay that do exactly what you are looking for.
When you have installed it can you post on SN that you will be running at SP on a very hot day.
We will all come and sit down with our popcorn to watch the results.
Why trick a sensor that is trying to help you preserve you engine???

As to sensible answers - you need a cool air feed into the turbo and across the IC. The answer would be the holy grail of turbocharging though.

silent running

Glad that's all cleared up then...

Heat management, that's what it's all about when trying to extract performance from turbocharged motors. Get it wrong or forget to tackle it, and you will never see the best from your engine.

In simple terms, keep the hot bits hot and the cold bits cold and you can't go far wrong. Not easy when they're all under the same bonnet. But sometimes it works out nicely. For example for both NA and turbo cars it's a good idea to heat wrap the headers/manifold to keep the heat inside the pipe. On an NA car the idea is that the hotter the gas the more energy and the faster it will travel, giving a scavenging effect on the cylinders. On a turbo it's even more crucial as you want to retain as much of the exhaust energy as you can before it hits the turbine. The more heat in the headers, the more energy drives the turbine, the more efficiently your compressor works.

And then there's the double bonus that keeping the huge amounts of heat IN the headers and uppipe means it stays OUT of the engine bay which is just what you want.

It's worth doing a bit of reading around the subject.