Why is stock 930 headers bad ?
 

Just wonder why the late model ones (86/87/88) are bad compared other after market ones like B&B, GHL, ... And I mean the headers only, not cat/muffler.

Is it because the primary size are too small? Anyone took one apart before? Pictures?

thanks.

I am not an expert, but from my understanding OEM headers are often compromise flow for ease of manufacturing and cost.

In other words, there really isn't anything "wrong" with OEM headers, but there are much better aftermarket headers out there...

It is all about exhaust length to the turbo. Stock exchangers "wrap" around to the FRONT of the engine before joining up with the j pipe which feeds the turbo and wastgate. Headers like B&B, GHL, Schnell, etc. are oriented such that the primaries and collecters run to the rear of the engine prior to meeting up with the turbo. It is my understanding that 4 feet of tubing is removed when using the aftermarket headers. As a result the exhaust gases have a shorter route to the turbo thereby greatly decreasing turbo lag.

JP

Thanks guys...

I suspect my GHL is cracked - I smell exhaust in the passenger compartment. I still have my stock heat exchanger in the garage, so may be I can do some experiement with it; but thought I'll ask the experts before doing anything silly.

Don't really feel like spending another $2.5K for a new one - this one only last 2.5 years :(

I smelled exhaust in my car too... so I dragged my CO detecter in there with me and drove around for a long time. It never even peeped (thankfully). I tightened a few fittings, and it seems to have went away. Maybe it is a 930 "feature?"

If your GHL cracked after 30 months, I'd give them a hollar first!

What RSR said. They're also at least 20 lbs lighter, even with heat exchangers, where it counts most. I've got the actual weights somewhere and post them.

Flow with the stock J pipe version is not too terrible, however, the turbo will operate better with the more direct heat and flow from B&B type headers, although I'll bet its usable lifespan is probably shortened.

umm... maybe I'm over sensitive then? I don't see any cracks visually so I suspect if I smell something, the crack is inside the heat exchanger.

I only smelled the exhaust when under heavy boost. Do you smell it all the time? Just when the heat is on? Under boost?

The smell is very obvious under 2 conditions -
a) on start up, kinda a puff
b) sudden heavy boost when its cold outside. But then, I can instantly see the windows fog up too

Rest of the time, I think I can smell a little. As a habbit, I always keep the windows opened a tiny bit.

That should delay your being poisoned by carbon monoxide a tiny bit. ;-)

ok - I hear ya.... that is why the original question ;)

Why is stock header bad?

The stock later 930 heat exchangers are the same design as the early/late Euro 930 heat exchangers.
They are not bad, aftermarket heat exchangers are just better. As previously stated the stock exchangers dump into a tube that wraps 2/3 of the way around the engine making for a very long run. Aftermarket exchangers are typically short runs strait to the turbo. Shorter runs allow for heat retention and quicker gas travel time = less lag/more power.
Are they $2000 better? Not to me, but if you want your engine to be all it can be they are a must.

Euro/Late 930 Exchangers:

http://forums.pelicanparts.com/uploa...1159663088.jpg

I think more than power, the primary advantage of aftermarket headers is drivability. Having owned a 4spd and 5spd turbo, I would say that the effect/drivability on the 4 spd was much more pronounced, and the first upgrade I would make on any 930.

Well, my GHL is cracked (I suspect) so I'll be looking for some solution. And with my now 3.4, I am thinking about custom fabing something from the stock ones i still have hence the question.

So, if I can shorten the factory design and fix the GHL problem (WG dump section too small) at the same time, it may worth something as opposed to cut open the GHL heat exchanger and fix that?