Are Holden cats the same as HSV

[zer05]

just bought my car and old owner gave me a set of HSV headers he had bought but not fitted to the car. Have read heaps of threads about people fitting them with aftermarket cats or the hsv ones that came with the headers but are the factory Holden cats different to what HSV fit. They seem to have the same part numbers #92183835/6 but can't find anywhere that says they are different in some way. If they are the same will the existing Holden ones bolt straight onto the hsv headers.

 

[monstar]

Different

#onethousandwords

 

[lmoengnr]

Externally different, but the inner substrate is the same.

 

[Poontang]

Is there much of a performance benefit in doing this?

 

[monstar]

Is there much of a performance benefit in doing this?

Yes slightly. Better sound and more useful torque.
The next stage is to fit decent downpipes and HFCs, CAI and tune and yeah loads more power (see illustrations below).
Back to back clear to see the HSV are hand made extractors whereas the stock manifold is a cast log.

Stock log is functional and easy to predict using stock tune but not ideal:

HSV extractors are better design and respond to tuning (for better or worse) but the better volumetric flow highlights an issue with the location and type of cat:

So the next stage mentioned above requires a tune but yeah is worth it. Simply a short 2" mandrel downpipe section to a stubby universal HFC barrel:

You can DIY as above, get the shop to make it or buy something online:

Bottom line is a shop can fab these out of 2" mandrel and cheap steel HFCs, flange out for as low as $450. Ready made parts from HM and I think X-force sell for $600 a pair
Plenty of information about this mandrel bend mod via search, is good for up to 300rwkw. It is important to note there's more to performance than top RPM hp though, and as such there are better headers (and collectors). But few as cheap and bolt-up like this.

 

[Poontang]

Thanks for the reply, great info.

 

[zer05]

Thank you Monstar very helpful stuff, how easy is it to install the hsv headers and cats. Is it take off and bolt the new stuff on or are some mods required.

 

[monstar]

Thank you Monstar very helpful stuff, how easy is it to install the hsv headers and cats. Is it take off and bolt the new stuff on or are some mods required.

Yes you can swap the whole header and cat each side easy. Again this a cheap basic improvement that's worthwhile to do yourself, vs Stage II with CAI and tune that is more involved but makes a big difference.

 

[dgp]

I installed the HSV headers and cats on my VEII Ute, no other mods at all, it sounded better and picked up some torque down low (seat of the pants)

 

[ozNick]

HSV 340 headers had bigger cats than standard HSV ones.
The outlet on the HSV 340 cat is 2.5 inch rather than 2.25 inch.