Collapsed Metalcat

[Tangles]

When it collapsed, what did the car actually do? Did it just lose all power and not make any more? What made you know it was the cat?

was on the dyno for a tune, but made same as before with too much timing

as soon as I picked it up it felt restricted, could tell really, tuners said check the cat and fix the fmic pipe

so checked the cat, was all warped inside and bent, cleared it out, then back on the dyno to fix the crap tune

206kw at 14psi, but the turbo is now the restriction - then redid the fmic so it works real well now, as 1 corner was warped and not letting thru 100% volume

now with 16psi feels fantastic, reckoning around 210kw dynobum

down 25kw with the turbo, so looking for a garret bb I can alter with my housings to harness 235awkw (auto heavy stag)

headwork makes the engine feel like a 25/30 so Im happy as larry, just need to get a better flowing bb turbo

[GTRsean]

I had a metal cat (barrel type) last for two years then finally kark it on a dyno tune. Went from 20psi to 11psi due to guts of cat blocking the exhaust a little. It was rattling around due to it separating from the body. Bits were shooting out the back lol.

Anyway, ended up getting a new one and this seems to be the mark II. It has a rod welded across the back of the matrix to stop the guts moving around I guess when it heats up and cools down.

I'll see how it goes.

[PM-R33]

Hmmm im nearly convinced that it's the cat to blame on my car now. Cheers for the replys guys, ill let you know if it was the cat.

[Fastrotor]

I reckon thats more work than unbolting the exhaust from the front pipe (because you've gotta get a pressure sensor then )

Yeah i guess so for those , but its something to keep in the tool box forever once its done...... i should make a heap up and sell them i think !

I do far to many cars to not have one with me..... and ALL dyno shops should have one anyway ! So easy to just whack it in and log on a second map channel. !

Hey i just re-read your comment and you said "you've gotta get a pressor 'sensor'" ...... all i mean is make up an adaptor (18*1.5mm thread to hose barb adaptor, and using some silicon hose , plumb it to a spare, or your current, "BOOST" gauge ...) ...can't get much simpler than that !

Gary

[R31Nismoid]

Thats true - not too hard... but then its not a one-fits all thing (GTR 32 and 33 i know are different in size for one)

So ye, overall long term it would be.

Once off though arguable

[666DAN]

Magnaflow FTW, I avoid the "other" branded one like the plague due to the amount of epic fails I've seen them have.

[badhairdave]

my 5inch catco went the same way as sean gtr's.

It just worked it's self loose around the edges and proceeded to unravel from the outside of the substrate.

The outsides of the cat didn't have a mark on it from scraping or anything so i figured it was a manufacturing fault. other than the separation the guts looked good, no melting or whatever. It got punched out and flames started to appear on over run

[PM-R33]

Yep was the stupid f**king cat afterall! Power went straight away from 170kw to 240kw....however now it won't make more and we don't know why. God it never ends!!

[hotchoc]

Yep was the stupid f**king cat afterall! Power went straight away from 170kw to 240kw....however now it won't make more and we don't know why. God it never ends!!

that's a 70kw gain mate, what else do u want : D

[PM-R33]

Nope, its a 20kw loss still. Before the head and the cams the car used to make nearly 260kw on around 17-18psi. Now with the headwork, poncams and 20psi it only makes 240kw.

[Fastrotor]

Measure the TIP , if turbos out of puff and TIP is high, larger cams with more overlap can cause power to go backwards.

Gary

[PM-R33]

Sorry what's TIP?

[Fastrotor]

Turbine Inlet Pressure. Anothers words, measure the pressure in the exhaust manifold. This will give you the info to work out the MIP to TIP ratio ( boost to exh mani pressure) , If its over 2:1 then your in trouble.

With high exh backpressure, due to small turbo housings or restricted exhaust, larger overlap cams just give it more time to pollute the intake charge more, and drop the knock point, resulting in less power.

Hence why changing to a larger exh housing generally allows more timing to be added, due to less intake charge poluting.

If you've run out of things to check, this is the ultimate thing to check to check the turbo sizing to the job your asking it to do. Bit of an effort , but its quality data when you get it.

Gary

Edited March 26, 2009 by Fastrotor