Subframe Overhaul problems.... Advise needed!

[NickP]

I'd love to do mine looks like I'd need some pretty hefty lifting gear.

 

[Fat Arnie]

Front end going back together. . Would have had the engine running today had I not found a leak in the oil feed hose to the oil pump. This is the replacement, so it's off to Pirtek in the morning to get it mended.

 

[Gp79]

Excellent job, shame about oil hose stopping you getting a run.

Pirtek is good idea as there is no point trying to get one from Maserati, unless there is stock somewhere it will be after Christmas!

I ordered parts last week to be told I'll get them in the new year, nothing critical luckily...

 

[Fat Arnie]

Wheels and fornt arch liners on in the morning. set the alignment, hit the road!

122 man hours to complete work
Parts costs - £1496
External services (paint,powder coating/plating etc - £924

 

[Gp79]

Nice one, don't get it salty!

 

[BennyD]

It looks great, well done. Such a shame you still have those crappy cats in the headers, what you need is a set of 4200 catless headers.

 

[Fat Arnie]

It looks great, well done. Such a shame you still have those crappy cats in the headers, what you need is a set of 4200 catless headers.

Benny,


IMO the ROI on changing the headers, even if they were free is zero. Have you seen how big a job it is to change them and how many other parts you need to change? For a barge like a GS, its just not worth it.

 

[BennyD]

For one thing it would prevent 'suck back' if the cats start breaking up. Also, with the restriction of the cat and gas flow direction change at the bottom, there can only be an improvement in efficiency and power if removed. I certainly wouldn't put those things on mine.

 

[FIFTY]

Well done Arnie, like I mentioned before it's a very admirable project I wish I had the skills and garage to do the same to mine. Getting a smug sense of accomplishment or glad to have it behind you?

 

[Mr K]

Nice job, must be very satisfying to get it all back together in much better shape for long-term ownership.

 

[Fat Arnie]

Well done Arnie, like I mentioned before it's a very admirable project I wish I had the skills and garage to do the same to mine. Getting a smug sense of accomplishment or glad to have it behind you?

Glad to have it behind me - far more work than I anticpated.

 

[Fat Arnie]

Benny, I think there is quite a difference between choosing to fit an exhaust with possibly poorer flow and living with one if what you already have. Cat breakup is a myth. Unless there is something else wrong with the engine it is not possible to have a vacuum in the exhaust. The cats in these cases probably broke up as other engine debris exited the engine. The only other way they break up is fuel poor mapping, and they either block or get distributed down the road.

The 2bhp I might gain (possibly at the expense of torque) is academic. You'll never feel it.

 

[BennyD]

Ok mate, I'm not arguing.However, there is at least one Indy who would vehemently disagree with you, but I couldn't give a dead rate a55 to be honest. Also, if you believe there is only a 2bhp gain in removing a 600 cell cat then, good for you. I think there is more but let's just agree to disagree. I would be interested in the source of the 2bhp gain reports, personally, I think is bolloxs and if you fall foul of the 'suck back' 'theory', I promise I won't laugh. All the best.

 

[Fat Arnie]

Even in a car with considerably more valve overlap than a 4200/GS there is no point in the cycle that the pressure in the manifold is greater than the pressure in the combustion chamber. Its a rubbish theory. What's more is Googling the subject reveals it seems to largely only effect cars originating from Modena and its suburbs. Now imagine if you dropped a valve and half of the roof of your combustion chamber and piston crown headed down your exhaust, you might not expect your cat to survive.

As for power loss, my Caterham, which has a Scholar 1.9 Evo Rover K Series which is considerably more highly tuned than the GS engine (137bhp/litre) loses 1 bhp on the rolling road comparing the exhaust with cat or cat bypass. They take very little away.

Not everything you read on the internet is correct.

 

[BennyD]

Given the choice between your exhaust and mine, I would take mine everyday, for several reasons. That is all.

 

[conaero]

Ask Emtee, his primary broke up, couldn't exit via the secondary's as it blocked it, got sucked back into the engine as a sand, mixed with the oil, game over, scrap engine.

This was an issue with the Euro spec 4200 and early GS's with the two cats in one pipe. Maserati remidied it by using header cats then secondary's further down the system which remedied the cat break up choking and ingestion.

Arnies GS has the benefit of free flow secondary's which will further allow any primary break up to exit out the back, but for me, one pair of cats is enough, secondary's are just not needed and are only there at the request of the engine manufacturer to stiffer the engine output...the same as the squish pipes do.

 

[FelixV]

I just installed the larini sports cats on my car which has Euro manifolds from the factory and it is savagely loud with the x pipe and Tubis. Sounds like a race car. The car revs so much more freely too. Also had the air filter installed. Don't have to worry about cat break-up now as matt said because I have an early GS which had two cats in each pipe.

 

[mjheathcote]

Isn't one issue with the US spec cats in the headers (sorry, i'm british, manifolds!), that they can be damaged by speed bumps etc that can cause the internals to break up?
Having gutted a spare pair of EURO down pipes, a knock with a lump hammer and the internals easily break!
Regarding the power outputs, no way can the difference in flow between the US manifolds and EURO manifolds only be a couple of BHP...the US manifolds look like something you would see on a gas powered fork lift truck engine!!

 

[BennyD]

Ask Emtee, his primary broke up, couldn't exit via the secondary's as it blocked it, got sucked back into the engine as a sand, mixed with the oil, game over, scrap engine.

This was an issue with the Euro spec 4200 and early GS's with the two cats in one pipe. Maserati remidied it by using header cats then secondary's further down the system which remedied the cat break up choking and ingestion.

Arnies GS has the benefit of free flow secondary's which will further allow any primary break up to exit out the back, but for me, one pair of cats is enough, secondary's are just not needed and are only there at the request of the engine manufacturer to stiffer the engine output...the same as the squish pipes do.

It looks like we are both wrong about the cat break ups and I've also learned that 600 cell cats don't restrict gas flow because, apparently, not all we read on the Internet is true. We live and learn.

 

[mjheathcote]

This was an issue with the Euro spec 4200 and early GS's with the two cats in one pipe. Maserati remidied it by using header cats then secondary's further down the system which remedied the cat break up choking and ingestion.

Sorry not convinced about that being the case.