Off the Shelf Exhausts -How good at handling EXTREME heat?

[Blue_Joe 0]

Ok

 

The situation I have is this.......

 

With all the Mods I have now done to the car it seems that custom made exhausts just can't cope with the heat!!!!!!! My last centre baffle box was replaced due to it cracking. When we took it off not only had it burn't out all the baffles inside but the actual 1.5mm steel "mesh" that holds it in place had MELTED!!!! That was 2 weeks ago. I went back at the weekend to do my engine mounts and guess what. In 2 weeks the centre box is burn't out AGAIN!!!!

 

Bearing on mind if I floor it, it will flame out the exhaust on EVERY gear change! And it's not through overfuelling as such the car is set up to perfection!

 

But it just can't cope with the extreme heat. If you look under my car when on a ramp the entire system has turned bright blue with it. And the tail pipe that was originally stainless steel silver went gold in about 2 days.

 

The company that do the exhaust have been great but they have now changed the centre box about 6 times but there is going to come a point where although they will change it the manufacturer is just going to say no more to them when they take ANOTHER box back! And to be honest they are friends that run the company and I don't want to keep putting them in that situation!! And lets face it if they wanted to argue it - my car is FAR from standard and is far from the spec it was when they fitted it!!

 

So my thoughts are as to how well the likes of Milltek, Magnex etc be at coping with the heat! Will they fair better than the Longlife that I have at the moment. I can't fault the Longlife - it's lasted FAR FAR better than the powerflow - that just completely disintegrated in a few months. The longlife's only failing is on the centre baffle box so far (although I don;t think the other 2 will last too much longer!) But I'm not going to just remove the centre box and just have 2 silencers as my car (for those who haven't heard it!) is definatly loud enough and with only 2 boxes would be FAR to loud.

 

The exhaust company have said if I do want to have a different exhaust then they will fit it for nothing so no worries there!

 

But are they up to the job?????

[W3RKD 0]

i would be fitting an EGT gauge if i were you as if its melting exhausts its not right. Either that or there is some restriction in the offending box. What o/d is the system you are running ?

[Blue_Joe 0]

I don't think restriction is overly an issue - from the 4 branch which all 4 pipes don't meet until under the car and go into 1 with a diameter of 2" into the centre box and opens on the outlet of that box to 2.5".

 

Can't see what else could really be causing the heat to be that high other than the extremes of the engine. Everything is running spot on.

[Supercharged 2]

Could it be running lean?

[Crasher 3]

Could it be running lean?

 

Spot on Supercharged, it's not rich it is way too lean-too much oxygen and not enough fuel. If you had an 020 box with rod shift gears you would have melted the linkage bushes as well. You need to get the fuelling increased.

[dr_mat 0]

Can't see what else could really be causing the heat to be that high other than the extremes of the engine. Everything is running spot on.

 

I'd say something's wrong fuelling wise. Otherwise, by this logic, a Bugatti Veyron would melt the entire car body..!

[Blue_Joe 0]

Could it be running lean?

 

Spot on Supercharged, it's not rich it is way too lean-too much oxygen and not enough fuel. If you had an 020 box with rod shift gears you would have melted the linkage bushes as well. You need to get the fuelling increased.

 

It's not running lean. It's been set up to perfection when it had a full custom map at ship wizards. The running of the car is spot on. I've had it all checked over and it runs spot on.

 

But at the end of the day you have to remember that this is not an ordinary G60 engine. G60 engines generate alot of heat when they are standard so I think this is at the end of the day an exageration of that.

 

And at the end of the day it's going to be running even leaner soon as soon as the water/methanol injection is hooked up!!!!!

[dr_mat 0]

It's not running lean. It's been set up to perfection when it had a full custom map at ship wizards. The running of the car is spot on. I've had it all checked over and it runs spot on.

 

And is it still spot on? I mean was it cooking the exhaust when it was first mapped? If not chances are something's changed. What about the exhaust valve timing? Ignition timing?

[Jim 1]

I appreciate that its a tuned car Sam, but I think what these folks are saying is right. I just don't see how it can be right that even a well tuned G60 is destroying exhaust systems like this...

[Blue_Joe 0]

I appreciate that its a tuned car Sam, but I think what these folks are saying is right. I just don't see how it can be right that even a well tuned G60 is destroying exhaust systems like this...

 

But the only thing that could be increasing heat is really if as the others say it is running too lean - But as I keep stating we know it isn't!!!!!!!

 

As I've said before the car is running spot on - It's been looked at enough. With all the hassle I've had with building this car I get it checked and rechecked all the time as I'm paranoid about it!

 

The rest of the system is fine but at the end of it all it comes down to the centre box is quite close to the manifold join and this particular exhaust system can't seem to cope with the heat coming out of it and yes it is very hot.

 

Looking at all the aftermarket systems they all seem to run only two boxes and run a decat straight through pipe to the rear 2 boxes. This is where my car differs and I am running an extra cylindrical baffle box where the cat used to be to try and quieten the car somewhat as we all know it is a VERY loud car. I think this is where the difference lies.

 

To this end I think that perhaps aren't going to get a resolution with an off the shelf on e either by the looks of it.

 

My only other thoughts are a different custom made exhaust such as Blue Flame and see if they are up to it. But with a long conversation with them first so they know what they are letting themselves in for!

[dr_mat 0]

Bit worried about the "flames out the exhaust" bit too.. That's not normal..

[Blue_Joe 0]

It's always done that. I don't mean they come out the back of the exhaust but they can be seen in the exhaust when behind. That I think may be caused by the cam - I've heard you can get an of overlap IIRC but I might be wrong and talking out of where the sun shines again! :lol:

[dr_mat 0]

It's always done that. I don't mean they come out the back of the exhaust but they can be seen in the exhaust when behind. That I think may be caused by the cam - I've heard you can get an of overlap IIRC but I might be wrong and talking out of where the sun shines again! :lol:

 

Sounds like a reasonable explanation (the overlap, not the speaking bottom!), but it still means you're igniting air/fuel mix in the exhaust, not in the cylinders, which is somewhat detrimental to the exhaust unless it's a competition zorst ..

 

Perhaps you should ring Nasa and get some 2nd hand tiles off challenger?

 

You're lucky you don't have to run a catalyst .. you'd be replacing them everytime it flamed the exhaust..

 

(Should add that I think most cams overlap a little, but it's not usually enough to cause this kind of effect..)

[GazzaG60 0]

id go with lean and/or timing too.

 

thats the problem with mapping on the rollers and not on the road.

 

the cam in aG60 is phased for this reason. overlap is usally an issue in twin cam cars where the phasing is adjustable

[Supercharged 2]

Perhaps you should ring Nasa and get some 2nd hand tiles off challenger?

 

:lol:

[Kevin Bacon 5]

I reckon it's the quality of the exhaust personally. If the baffles are being destroyed, they're not made properly. If the fuelling is correct on the AF and the timing correct as far as you can tell, then it's got to be shoddy workmanship...... but my first instinct was lean running too, but you've assured us it's not that, so I'd change brands of exhaust personally. Stainless melts at around 1400 deg C (depending on grade) so you've got plenty of scope yet!!

[flusted 0]

Whats mike_g60 using? Im using a completley bodged 2 1/2" system that someone made and thats holding out fine

[vwdeviant 0]

I reckon it's the quality of the exhaust personally. If the baffles are being destroyed, they're not made properly. If the fuelling is correct on the AF and the timing correct as far as you can tell, then it's got to be shoddy workmanship...... but my first instinct was lean running too, but you've assured us it's not that, so I'd change brands of exhaust personally. Stainless melts at around 1400 deg C (depending on grade) so you've got plenty of scope yet!!

 

I'd go with that, I used to work in M/sport and that's when things get really hot! Stainless is the way to go for most club-sport (and Pros). You can see manifolds cherry red when some of the cars come in (Mazda Rotary-based single seater esp!) but they run silencers that don't "Melt". I've also run a number of styles on my air-cooleds with modded engines and much shorter runs, and even mild steel boxes have been fine.

Joe I know you say that everything's spot on but if it is generating that much heat (get it on a ramp and run it, see what happens) then I'd also look to a mix issue an maybe ask a second opinion?

[GazzaG60 0]

can't see why an exhaust would melt before an alloy head.

 

can anybody explain.

 

if fueling good id check timing. seen a manifold blow due to heat with lack of timing in the map. good job the manifold was weak or the head would be poo.

[Toad 0]

I think I'd try increasing the bore of the exhaust system. and the first silencer. A greater volume might not get so hot.

[Blue_Joe 0]

I think I'd try increasing the bore of the exhaust system. and the first silencer. A greater volume might not get so hot.

 

Thats exactly the conversation I had with Blue Flame today. They think the bore size is too small and think I should move up to 3". Also I need to modify my manifold as I think that is where the restriction is causing pressure build up and in turn heat build up. The manifold goes down to a 2" bore size before we increase it to 2.5". So basically I need to get a good engineer to cut off the end of the manifold and open it up to a bigger bore size more like 3" - then change the entire systems to 3" possibly!

[Toad 0]

Just increasing the bore size from 2.5 to 3 inches would increase the sectional area of the pipe by 42%

 

2 inch to 3 increases the area by 120% odd. So a fair increase in flow...

 

You'll probably see a bit of an increse in power too, well it'd be nice anyway...

[Lippy 0]

but dont do it before the RR day!!! you promised yourself no more projects ;)

[Blue_Joe 0]

No worries there fella - I'm not taking this task on until January fella!!!

 

Have a few plans for the beginning of the year before the shows kick off!!

 

Primarily exhaust system and respray!

[dr_mat 0]

Or drive slower .. ? ;)