1.2bar with 1st cat still in

Ive been thinking and kind of worrying a bit about the boost levels my car is running with the 1st cat in place, the exhaust system itself is very free flowing and its hitting 1-1.1 in the summer and 1.1-1.2 in the cooler weather, now here is the thread that has got me thinking

http://www.mkivsupra.net/vbb/showthread.php?t=139380

My thinking is, should I invest in some water/meth injection to bring my EGT's down...at the moment im getting 6/700 with the probe mounted after the 1st cat in the 2nd one.

Anyone got any views?

It's probably a very good idea to get your EGTs lower.

http://www.mkivsupra.net/vbb/showthread.php?t=139380

It appears that leaving the first cat in is believed to be responsible for this poor fellas woes.

I can't comment as to whether water/meth injection is a better solution than removing the first cat. Is there any way you can swap your decats i.e. decat 1st and put 2nd cat back in?

Mike

just realised you posted on that thread Mikey

Mike

It's probably a very good idea to get your EGTs lower.

 

http://www.mkivsupra.net/vbb/showthread.php?t=139380

 

It appears that leaving the first cat in is believed to be responsible for this poor fellas woes.

 

I can't comment as to whether water/meth injection is a better solution than removing the first cat. Is there any way you can swap your decats i.e. decat 1st and put 2nd cat back in?

 

Mike

Trouble is, I have tried and the boost is still higher than stock and is fighting a restriction all the time ie the cat be it first or second in place :(ive tried both out and was hitting 1.35/1.4 bar so I need to find a happy medium as it were I still need some big restriction otherwise the boost runs riot which is why I stuck the 1st cat back in as 1-1.1 is where I want to be

 

just realised you posted on that thread Mikey

 

Mike

Just edited my original

Ive been thinking and kind of worrying a bit about the boost levels my car is running with the 1st cat in place, the exhaust system itself is very free flowing and its hitting 1-1.1 in the summer and 1.1-1.2 in the cooler weather, now here is the thread that has got me thinking

 

http://www.mkivsupra.net/vbb/showthread.php?t=139380

 

My thinking is, should I invest in some water/meth injection to bring my EGT's down...at the moment im getting 6/700 with the probe mounted after the 1st cat in the 2nd one.

 

Anyone got any views?

Why are you still running 1 cat??

I'd suggest taking the 1st cat out. If you must run one, get hold of a second instead.

Trouble is, I have tried and the boost is still higher than stock and is fighting a restriction all the time ie the cat be it first or second in place :(ive tried both out and was hitting 1.35/1.4 bar so I need to find a happy medium as it were I still need some big restriction otherwise the boost runs riot which is why I stuck the 1st cat back in as 1-1.1 is where I want to be

Oops. Can you get restrictor ring put in along with 2nd cat to bring the boost down to 1 or 0.9 bar?

I'd certainly get a egt gauge and controller fitted if possible Mikey.

Why are you still running 1 cat??

See my post above sorry if its not clear.....its because I was hitting 1.4bar with both out and a restrictor as well so put the first back in to limit boost levels

Oops. Can you get restrictor ring put in along with 2nd cat to bring the boost down to 1 or 0.9 bar?

I'd certainly get a egt gauge and controller fitted if possible Mikey.

im reluctant to fit a second cat as the dynamics worry me a bit....ie no restriction for a large length of exhaust tubing and then all the gas hitting a restriction when it reaches the 2nd cat pipe, where as the other way round the restriction ends after the 1st cat back! not sure if this makes any difference or not. Maybe its me being anal. I already have an EGT gauge mounted in the 2nd de-cat pipe, I know its far from ideal as its far away from the turbos but its reading 6/700degrees in there which to me is high

I already have an EGT gauge mounted in the 2nd de-cat pipe, I know its far from ideal as its far away from the turbos but its reading 6/700degrees in there which to me is high

do you wish to expand on the shocked smileys...whats shocked you. Thats figure is after a right caining

Is this a bad thing?

I already have an EGT gauge mounted in the 2nd de-cat pipe, I know it's far from ideal as it's far away from the turbos, but it's reading 6/700degrees in there which to me is high.

See my post above sorry if its not clear.....its because I was hitting 1.4bar with both out and a restrictor as well so put the first back in to limit boost levels

 

 

 

 

im reluctant to fit a second cat as the dynamics worry me a bit....ie no restriction for a large length of exhaust tubing and then all the gas hitting a restriction when it reaches the 2nd cat pipe, where as the other way round the restriction ends after the 1st cat back! not sure if this makes any difference or not. Maybe its me being anal. I already have an EGT gauge mounted in the 2nd de-cat pipe, I know its far from ideal as its far away from the turbos but its reading 6/700degrees in there which to me is high

I've got some UK turbos for sale.....then you'll be able to run fully decatted.

do you wish to expand on the shocked smileys...whats shocked you. Thats figure is after a right caining

I am guessing because your EGT at port will prob be in excess of 900deg.

Don't cats function at higher temperatures than that, though? If the EGT gauge is after the cat......

hmmmm, I find this really weird then, my cat temp sensor is not showing up as a warning on the dash so I dont know whats happening unless the EGT gauge im using is reading wrong? Its a greddy gauge as is mounted about 3-4inches into the 2nd decat

im worried now

General rule of thumb is add 200-300deg if the probe is after the turbos and cats.

See my post above sorry if its not clear.....its because I was hitting 1.4bar with both out and a restrictor as well so put the first back in to limit boost level.

 

 

im reluctant to fit a second cat as the dynamics worry me a bit....ie no restriction for a large length of exhaust tubing and then all the gas hitting a restriction when it reaches the 2nd cat pipe, where as the other way round the restriction ends after the 1st cat back! not sure if this makes any difference or not. Maybe its me being anal. I already have an EGT gauge mounted in the 2nd de-cat pipe, I know its far from ideal as its far away from the turbos but its reading 6/700degrees in there which to me is high

General rule of thumb is add 200-300deg if the probe is after the turbos and cats.

So with Wez's calcs below your range is either 800 - 900 degrees but could be 900 - 1000 degrees. Second range is too high Mikey. As it's a rule of thumb your temps could in fact be higher. Doubtful 'cos you've still got turbos.

At the risk of being torn to shreds I'd advise re-siting the egt, putting the restrictor ring in and lose the cats altogether. Just keep the first cat for MOT if needed. I would say this will give you peace of mind and preserve your turbo life. Hope it comes out ok bud.

do you wish to expand on the shocked smileys...whats shocked you. Thats figure is after a right caining

 

Is this a bad thing?

I Would move your egt probe to your 5th or 6th cylinder manifold runner as i think you will be in for abit of a shock.

Normally the hottest place in a turbo exhaust system is at the turbo exhaust housing as all the heat energy combines here and hits a restriction which is the turbo. Bigger Ar housing cause less of a restriction so less heat builds up then.

I always recommend fitting the EGT probe in the runner but some worry that it will break and go through the turbo. Fix here is buy a decent EGT probe.

When the exhaust gas exits the turbo into the downpipe it generally loses around 150c-200c depending on wrapping, exhaust diameter and if there is a cat in place.

BUT When a very restrictive 1st cat is in place the heat energy barely drops when it exits the turbo due to the pressure build up from the restriction and then actually causes the whole temp back from the exhaust port to rise.

Measuring the temp at the 2nd cat is like fitting one of those narrow band o2 gauges. A complete waste of time!

Based on other supra's i have seen which are only running 1bar with the 1st cat i would expect your temps to be easily over 950c at the manifold when running 1.2bar.

Ryan

might be overlooking something here but as steel/iron approaches 900-1000 degrees it is usually glowing quite noticibly.

Maybe take it for an extended burn and pull over quickly and look for a glowing manifold?

Maybe take it for an extended burn and pull over quickly and look for a glowing manifold?

So if you are unsure the car is running too hot, take it out for an extended thrashing and see if it glows

Prob not the best idea is it.

i find it incredible that people go to the trouble of getting something like an EGT gauge then fit it completely wrong just to look cool, what is the point

So if you are unsure the car is running too hot, take it out for an extended thrashing and see if it glows

 

Prob not the best idea is it.

You are right its not a good idea but the method behind the obvious madness was that the car is been driven anyway and its got to be worth a look after a drive.

my car has both cats and on occation i have upped the boost to just under 1 bar. I have not had any problems yet but then i dont tend to push my car for long, just the odd short burts of acceleration.

I am guessing because your EGT at port will prob be in excess of 900deg.

Shite.... its been like this for over 2 years now, but only been highlighted since my EGT has been in

So with Wez's calcs below your range is either 800 - 900 degrees but could be 900 - 1000 degrees. Second range is too high Mikey. As it's a rule of thumb your temps could in fact be higher. Doubtful 'cos you've still got turbos.

At the risk of being torn to shreds I'd advise re-siting the egt, putting the restrictor ring in and lose the cats altogether. Just keep the first cat for MOT if needed. I would say this will give you peace of mind and preserve your turbo life. Hope it comes out ok bud.

It did run lower temps when the 1st was out but my boost was totally out of control, I couldn't be arsed messing about trying to get it spot on which in my opinion is more hassle than its worth given the crude method of raising it in the first place, I could imagine getting a smaller Restrictor for winter a slightly larger one for summer and also getting a cat put back in for MOT's....to me thats way to much greif getting it changed all the time:(

I Would move your egt probe to your 5th or 6th cylinder manifold runner as i think you will be in for abit of a shock.

Right im officially worried now what damage has been done might end up going single quicker than I first though

What sort of damage can occur from these sort of tempratures?

BUT When a very restrictive 1st cat is in place the heat energy barely drops when it exits the turbo due to the pressure build up from the restriction and then actually causes the whole temp back from the exhaust port to rise.

 

This is the part I always get confused with.....so what happens with a stock car with a stock exhaust, surely that is even more restrictive? how are the EGT's effected when its stock

This is the part I always get confused with.....so what happens with a stock car with a stock exhaust, surely that is even more restrictive? how are the EGT's effected when its stock

If you have a stock exhaust system then you will be running stock boost. So the exhaust energy will be less