Manifold Advice

[chrispitman]

After a bit of advice nearly got the manifolds off the car (chimera 4.5) got a couple stubborn bolts left. I was looking to do a few things

A - Remove Pre Cats as every body says it dosent effect the emissons for MOT.
B - Looking to get the manifolds and Y Piece ceramic coated inside and out to reduce heat, but dose this cause problems with more head buildup under the car. Any recommendations of company which do a good coating job.
C - Befor doing above is it worth porting the manifold to gasket or are these generally OK.

[900T-R]

Logic would say more of the heat contained by the exhaust gases would stay inside with a ceramic coating, keeping the outside of the coated parts cooler (well, relatively speaking) and keeping exhaust gas velocities higher so that the exit is found more quickly. I'd wager a guess that exhaust gas temperatures at the tailpipe would be a bit higher, then.

But then again, I could be awfully wrong about all of this (you saw that one coming, didn't you?...

[spend]

A, precats just enable emissions to be met when cooler ~ just heat car up first. Seems a very cost effective power upgrade.

B. No noticeable heat effects in lower exhaust. Manifolds have a few very hot spots ~ these are removed with coating.
You cant have the Y-piece internally caoted where the cat is Cam-U-Coat are the company that all use AFIK.

C. Manifold port should be OK ~ any porting reqd is normally on the heads, but your heads may already be ported to some extent.

Dave

[clive f]

Agree with Spend, as for the camcoating, contact Tim at Act, he will get them done cheaper via camcoat than you will get done by going direct to camcoat yourself.

[im]

spend said:

A, precats... Seems a very cost effective power upgrade.

How does removing the pre-cats increase power? Perhaps 1 or 2 bhp but not really "cost-effective" - unless you DIY.

I had my pre-cats out and it didn't increase bhp by even 1.

I understand the point I think you'll make re: back pressure but I don't think it'll make any "real" difference - certainly not a noticable one.

IMHO

[spend]

im said:

I had my pre-cats out and it didn't increase bhp by even 1.

The contents of your pre-cats were probably living in your Y-piece in that case

I think 3-5 BHP is norm quoted as the outcome of this surgery.

Dave

[im]

spend said:

im said:

I had my pre-cats out and it didn't increase bhp by even 1.

The contents of your pre-cats were probably living in your Y-piece in that case

they were fine - I was having my manifold gaskets replaced. They (Austec Racing) asked if I wanted the pre-cats out at the same time as they were in the area anyway. I asked what this would do and was told that it would change the 'exhaust note' a little but that they couldn't say that it would have any effect on bhp.

Sure enough, as measured on a RR - No difference at all.

spend said:

I think 3-5 BHP is norm quoted as the outcome of this surgery.

Dave

Hmmm, I think that has more to do with the 'quoter' wanting your cash than it does anything else

[andy-w]

sure there used to be an advert for a place that would do an exchange service for your y section and manifold....thought i had it saved in my favourites but i havent....which is annoying because i was going to swap mine...

IIRC it was up near Blackpool....

[chrispitman]

Thanks for the replys

When you go for stage 1 or 3 heads are the standard exhuast ports OK, or do they have to be enlarged. This is what I would like to know before coating them.

[CHEF_GOLF]

just do what i did removed all the cats and had a stainless manifold made and found a sympathetic garage to mot