NC Catted Header

[LuckyCat]

If you want I can measure the clearance between the “standard” Goodwin header and the steering shaft. With this information you may be able to get Brian to give you an answer on clearance.

Yes please that would be most helpful.

I did find a picture of an OEM header at http://competitiontyres.com.sg/trackday ... ed-mx5-nc/ . It's an ugly looking piece of plumbing, wouldn't look out of place on a star wars set.

But yes, thank you if some measurements can be taken !

c

[Charlie Brown]

Clearance is tight to the steering shaft from the GWR headers.
The closest tube is #3 which is 6mm from the steering shaft, at a point 100mm vertically below the rear bolt that attaches the heat shield to the body.
Hope that helps.

[LuckyCat]

Clearance is tight to the steering shaft from the GWR headers.
The closest tube is #3 which is 6mm from the steering shaft, at a point 100mm vertically below the rear bolt that attaches the heat shield to the body.
Hope that helps.

Thank you!
That info plus Neils photos have been very helpful indeed.

regards
chris

[Charlie Brown]

FYI, I sent the dimension to Brian on Saturday and this was his reply.

Hi Phil

The upper half of the new header and our full header...is the same part. To make the original prototype of the new catted header we cut off the bottom half of the full header and then add collector and converter. We then make lots of small adjustments to gather the tubes down into the collector a bit cleaner. Thus, I expect the results will be about the same in terms of fitment.

Early next week I will lay the two on the ground and compare how much each comes off the ground. That should confirm that the new header does not come any further from the motor than the old header....at least at the point the steering shaft passes in the photos I have seen today.

Brian Goodwin
Good-Win Racing
http://www.good-win-racing.com

[NitroDann]

any reason someone hasn't taken an aftermarket header to a local shop and have the extra cat added? perhaps a 3" cat?

Dann

[Charlie Brown]

any reason someone hasn't taken an aftermarket header to a local shop and have the extra cat added? perhaps a 3" cat?

Dann

CAT on header really defeats the purpose of adding the header in the first place, that being getting as much power as you can.

It’s different in the US (California) with their strict yearly exhaust emission testing, but the US boys are very keen to gain just a few extra kW and still pass the exhaust test, so the catted header is the way to go for them.

Remember the NC has two CATs standard. When we add a header it deletes the first CAT. I believe that there’s been some NC’s checked with just the second CAT fitted and have passed our testing, others have failed. If it doesn’t pass, all that needs to be done is to cut out the second CAT and put a bigger CAT in its place to pass emission.

I think going down the catted header route in AU is a waste of money. You’d gain more power from a reflash, which is something you need to do when adding the header anyway.

[Sailor]

Agree totally with you Phil!
Why go to the trouble and expense of fitting the still restricted catted header which is still NOT ADR compliant?
The ONLY reason that cat is installed so close to the engine is so it will heat up almost instantly, something that is required for the -7 degree? cold startup required for the original emissions test (Euro 3 IIRC).
This test is not required on our NCs to pass emissions REtesting.
As you say some have passed with only the small rear cat but I'd bet it was very close.
Fitting a larger free flowing cat to the midpipe after installing a nice free flowing header is a much more viable option..

AND I still have reservations about putting the aftermarket catted header UNSHIELDED in that location so close to vitals where originally heavy insulation with an airgap was required on the original cat.

[NitroDann]

I guarantee that compliant turbo NCs will have a cat before the first factory flanges as well as the stock secondary cat.
A 3" cat on a 2" exhaust is a compromise in flow velocity but certainly is not a restriction in a 2.5" exhaust system.

Dann

[wozzah1975]

any reason someone hasn't taken an aftermarket header to a local shop and have the extra cat added? perhaps a 3" cat?

Dann

CAT on header really defeats the purpose of adding the header in the first place, that being getting as much power as you can.

It’s different in the US (California) with their strict yearly exhaust emission testing, but the US boys are very keen to gain just a few extra kW and still pass the exhaust test, so the catted header is the way to go for them.

Remember the NC has two CATs standard. When we add a header it deletes the first CAT. I believe that there’s been some NC’s checked with just the second CAT fitted and have passed our testing, others have failed. If it doesn’t pass, all that needs to be done is to cut out the second CAT and put a bigger CAT in its place to pass emission.

I think going down the catted header route in AU is a waste of money. You’d gain more power from a reflash, which is something you need to do when adding the header anyway.

Bingo. Best to fit the best headers you can find rather than muck around with something that will never work correctly. As soon as you fit a Cat in a header system it upsets the function of the header, defeating the purpose of it in the first place.

IMO, Either you fit a decent header and a cat after the end collector on the header, or forget about the process all together. The catted header is a waste of time and money.

Cheers
Woz

[NitroDann]

So hang on, the catted header has the cat BEFORE the collector?! That's what's wozzah implied. that is silly.

Dann

[wozzah1975]

So hang on, the catted header has the cat BEFORE the collector?! That's what's wozzah implied. that is silly.

Dann

Maybe not before the collector Dann, but I would suggest that the merging point, in this case the Cat would be
-in a compromised place giving the wrong length for the runners
-more than likely making a 4-1 design, also a compromise
-creating an expansion area in a bad place

Cheers
Woz

[NitroDann]

Understood. The other solution is of course a complete replacement exhaust built for the purpose which I imagine would have flanges in different spots.

That's one if the problems I always have when building exhausts parts for people who want it to fit other 'bolt on' parts, flange count and location as well as pipe location and muffler location are dictated by factory design.

A complete custom system removes all compromises. I bet a set of 4-2-1 NC headers opening into a long but low cell count cat fitted around the same place the stock first flange is and followed by a free flowing 2.5" system would achieve all of the goals here. However needing each part to bolt onto stock flange locations doesn't allow this.

Dann

[wozzah1975]

Understood. The other solution is of course a complete replacement exhaust built for the purpose which I imagine would have flanges in different spots.

That's one if the problems I always have when building exhausts parts for people who want it to fit other 'bolt on' parts, flange count and location as well as pipe location and muffler location are dictated by factory design.

A complete custom system removes all compromises. I bet a set of 4-2-1 NC headers opening into a long but low cell count cat fitted around the same place the stock first flange is and followed by a free flowing 2.5" system would achieve all of the goals here. However needing each part to bolt onto stock flange locations doesn't allow this.

Dann

Looking at a direct comparison between the OE header and the GWR item, there is no doubt it is better. The runners are longer, and collect much nicer than the OE item. However, as far as the advertised gains and dyno results go, as always with self dyno'd results they'll be inflated, and the worst result compared with the best result over all of there dyno runs. I only ever trust independant results, and even then I'm wary as dyno people can be persuaded to fudge figures as well. I have no doubt that there would be a power increase, but no where near the advertised figures.

However, if you were to compare the OE header with a decent 4-2-1 header, and a cat mounted in the correct position the results would be far better than the GWR item above. But as you stated not a direct fit.

I guess it comes down to the individual, but there is no way I'd spend that sort of money on a sub standard header arrangement for any car.

Cheers
Woz

[Charlie Brown]

Pictures, details and dyno results here: http://www.good-win-racing.com/Mazda-Pe ... -1155.html

[wozzah1975]

Pictures, details and dyno results here: http://www.good-win-racing.com/Mazda-Pe ... -1155.html

You beat me to it

Cheers
Woz