Going From Shit Ceramic To Gutted Cat

[Trozzle]

Sorry, I gave a search a shot, but frankly I haven't a f**king clue where to start with keywords >.<

Since I had an issue with my shitty ceramic cat which I resolved by bashing it out, my car is significantly down on power both on boost and off. I knew that it would cause my AFR to be slightly leaner, but had been told this would not be by very much. The car ran really well for about 2 weeks, but has begun to deteriorate lately...

I spoke to my workshop this morning, who advised me that the cat being bashed out would cause the AFR to become lean enough to potentially do damage...I don't necessarily think this would be the case, but I have limited knowledge and simply go by the idea that I can't fathom it making THAT much of a change. Because of this, I'm here putting it to you SAU - if my car was making 294rwkw on ~16psi through a hypergear highflow at roughly 11.5AFR, would me bashing my cat out cause this AFR to lean out enough to do damage? If NOT, how often do cam belts jump a tooth on either cam gear? The belt should be a tad less than 70,000km old. This scenario would explain the loss of power both on boost and off.

The car doesn't blow smoke on or off boost.

Doesn't burn/use a noticeable amount of oil

Hasn't thrown enough oil out of the rockers to even make it halfway to the catch can.

Thanks again for helping me out with my 9001st thread about my problems.

[Dobz]

I couldn't imagine a gutted cat would make any real diference to afr's. It's probably unlikely your timing belt jumped a tooth unless it hasn't been tightened properly or the tensioner came loose but you could whip the timing cover off and check to make sure. The best way to go if you feel it's down on power from what it was is put it on the dyno.

[StealthX]

Get a nice stainless cat in there for good measure.

shouldn't have any affect on AFRs. Unless the factory o2 sensor is located AFTER the cat, which it's not. there's simply no way the cat can effect the fuel mixtures. At the tailpipe, YES, but at the turbo/motor/head, NO.

[Moodles2]

As far as I understand it, the cat body compensates for the internal volume the castrate would normally take up.. take away the castrate the extra space inside the body creates areas of turbulence affecting exhaust flow that could make the gutted out cat worse than a normal working cat.

[Trozzle]

Well it's certainly down on power, there's no doubting that. It made 294.4rwkw on the rollers and was (as you can imagine) wheelspin central. Now it refuses to lose traction in 2nd under WOT.

I'm sure a gutted cat would create a small amount of turbulence, but certainly not enough to reduce my power throughout the rev range as I'm experiencing...Also, after first gutting the cat and refitting it, the car was running awesomely - instant wheelspin when boost comes on in 2nd, and really wanting to let go in 3rd as well...

Finally, that's exactly what i was thinking Cam. Although it is possible that they will be slightly affected due to a much more freely flowing exhaust, certainly not to the extent my workshop was suggesting. It was as though I was blaspheming to the Pope's face the way he carried on when I told him the cat had been gutted, suggesting piston damage etc...lol

Unfortunately if it ISN'T serious damage from leaning out (which is why I asked here to remove this option), if the timing belt hasn't jumped a tooth, or if my valve springs haven't shit themselves hard....then it's the turbo. I don't want it to be the turbo, nor do I really think it will be. At one stage it didn't *appear* to make full boost correctly, but I can't be entirely sure...

[17psi r33]

hi i have had a quick read with regards to you problem and think your turbo will not be the problem unless something strange like turbo overspeed has occoured from the exhaust and wheel damage has happened? is it maintaining the set boost level through to red line? if so there should be nothing wrong with is without the usual noise that you (would) notice. i hade similar problem of loss of power, im making the same levels of power you are and had a jim berry full monty clutch in the car< one of the best clutches in my opinion you can get, after a bit of chasing around like you did (and this clutch was only 10000km old) i decided to pull the box as the only explination was clutch slip even though i would not show like usual ie free rev or sudden rise and fall during wot, when clutch was removed the pressure plates were stuffed and it was from small amount of oil that had leaked in. cause heaps of problems to find what cause of power loss was, but oil leak is fiaxed now and hay presto wheels spin central here we come. oh and jim berry did a fantastic job on new replament clutchas a few mods were done this time as i do more drag racing thank street driving.

[Trozzle]

I considered clutch slip too, but the revs are very slow to rise as well...it's very steady increase in RPM, but also very slow....

It does hold boost through to red line - at least it holds it as well as it did when it was tuned. It's running straight off the actuator, so boost does drop a bit but it's consistent.

I did recently have my intercooler piping come off when my cat suffered meltdown (apparently sudden blockage of the cat can pop cooler piping? lol) which may have caused the turbo to spin somewhat faster...but Stao (Hypergear) doesn't believe this would have done anything. The turbo itself does make a very quiet sound while idling - not a whistling sound, kinda like the bearing moving (it's a bush bearing, not BB) but has done this since it was put on the car...

I'll be booking it in for some dyno time and inspection once the workshop opens up again, but unfortunately that isn't until next tuesday...so hopefully I can get it in before next Friday.

[17psi r33]

pull intake off and check shaft play by hand, you may have had oil starvation to turbo and cooked bearing, or bent shaft. but no i cant see blown intercooler pipes from blocked cat all it would do is limit the turbos ability to spool up. have you checked your waist gate? is it a built motor? its hard to say without hearing the motor run.stupid question but you didnt get any of the cat stuck down the exhuast? ie blocked exhuast.

[KiwiRS4T]

To check exhaust unbolt it and secure the loose bits. Drive away as slowly as possible from the house and then boot it to test acceleration and then sneak home before the cops get you.

[Trozzle]

Not that I know of. I'm 99% sure ALL the cat came out when I bashed it.

I'll check shaft play this evening, haven't had much time to pull stuff apart lately

I agree with the blown piping...it should only really limit the turbo due to exhaust restriction...didn't make sense at all at the time lol

engine isn't built, it's unopened to my knowledge.

[17psi r33]

yea was just checking with the built motor cause the slow reving thing might have been a big end or spun crank bearing but highly unlikely as you would hear it for sure. and a cam being skipped a tooth or to would be minimal differance maybe 5-10hp give or take 5-6 teeth skip and motor would be up the creek ie maybe valves hit piston. you might have broken a valve spring although they still not a problem at that power level but strange things do happen. i would also check your cooler pipes as you siad you had them done recently mainly the end tanks from the intercooler for anything blocking the inlet or outlet. i also wonder if you have a stuffed fuel pump thats an easy one tho check though, even fuel filter is a posibility. sorry just rattling things off to look at.

[Trozzle]

haha yeah all those things can make sense, but all unlikely...it doesn't feel like it's labouring the engine in low RPM, it just feels like it quite simply doesn't have any power. Not like it has power, but is being held back...although, there is an audible ticking sound come from under the car while idling (clutch in or out doesn't make difference) but that has been apparent quite some time ago and then went away...came back recently though, so it might be related.

if the intake cam skipped teeth, that could explain lack of power while still maintaining correct boost. Boost shown on the gauge is simply an increase in manifold pressure...doesn't mean the same volume of that air is making it into the cylinders. Depending on which direction the gear skipped teeth, it could perhaps somehow limit the amount of air entering the cylinder? Open duration would obviously remain the same, but this would be to the same effect of VCT changing power curve.

I can almost guarantee that the piping from turbo outlet all the way to throttle body is free of leaks or blockages. This is with the exception of INSIDE the intercooler, as there's no way I can guarantee that hasn't somehow become blocked. This is because I redid all the piping myself with the 10mm nut T-bolt clamps, after degreasing all parts first. Only joins that weren't redone with these bolts are the 2 on either side of the very final silicone piece before the throttle body.

Also fuel pump and filter are only a few months old. Pump is a bosch 044 running in-tank. a couple of times it has been noisier than it usually is, but I haven't been down on power specifically at these times. I put it down to cavitation or something to do with getting warm.

[17psi r33]

reason for checking boost is not quite right yes its a set value but if turbine is damage or exhaust wheel broken you will notice the boost level drop at higher rpm as the turbine will not be able to maintian the volume or pressure required. i to have an o44 intank and noise does not mean much you back off throttle and will hear the pump load up as you fuel reg closes allowing the pump to flow max back to the tank. under wot the pump will go silent as there is no resistance on it just strait to the motor supply. and slight cam change can affect how the turbo will responed on the exhuast side but it will still boost just later or earlyer depending on the direction of movement, thats also why i asked about valve springs a broken one may not clove or open valve all the way and cause i few problems thats for sure. my vct sensor was stuffed and not triggering which was found through dyno tuning but did not make that much of a difference. motor not being able to rev is verry odd, hence the direction to crank or big end. how many km on motor?

[JonnoHR31]

other way round, pump loads up under WOT

as said, drop the zorst at the dump and try again.

also to make sure clutch is fine, load it up in 5th and watch speedo vs rpm. if it doesnt slip in 5th at peak torque then its not gonna slip anytime

[Trozzle]

can guarantee it isnt the clutch. Lazy revving combined with feeling low on power doesn't seem logical. If it were clutch slipping, it would either jerk a bit on the revs under power, or give way all together and rev out. It's neither, it's just slow to build revs.

My boost drops at higher RPM as I'm not running off a controller of any kind. Straight from cooler piping to actuator.