Extrude Hone

Some co-workers and I were discussing CA-emissions friendly mods (lame emissions I know). Since I don't know of any "friendly" test-only stations, I can't have LT's, and the consensus on this forum is that shorties don't do anything. A co-worker mentioned having the stock exhaust manifolds extrude honed. I never heard of it (I know what it is now), but I want to know if there are any performance gains to be had/noticed?

on an lt1 or ls1?

Lt1.

What about mid length headers? Better ground clearance too.

Or r&r lts every 2 years :lol:

Any headers that move the cat and I will fail smog test. Remember this is Cali.

Ya but I'm sure you can find someone that will overlook the visual part. Do you have to take your car to a test only station? If you do then you're hosed. If not, then go with mids and just hit up the ghetto when smog time comes to have someone overlook the cat being moved (if they notice at all). If you know anyone with smog legal headers, have them get you a carb sticker and you're good to go.

Yeah, I have to use a test-only station.

the consensus on this forum is that shorties don't do anything.
lol... ok. You think shorties don't "do anything"? :rolleyes:

Seriously, extrude honing stock manifolds will have WAY less flow than shorties would. It's an option for those with no cheap header option (rare engines/chasis), or for those who insist on orginal numbers-matching castings... but cost per hp its pointless for our purposes.

I think you should look into shorties more seriously.

Well I guess that's my only option.

I think there used to be maybe one or two midlenth headers that didn't move the cat for the LT1's, but I think they are hard to find now/they don't make them anymore. I had smog legal mids on the V6.

I don't share the opinion that shorties are worthless. But yes, they are pretty much your only option.

compared to stock lt1 manifolds, shorties are an improvement.

the real "shorties are pointless" arguement pertains to the later model LS1 manifolds.

I think there used to be maybe one or two midlenth headers that didn't move the cat for the LT1's, but I think they are hard to find now/they don't make them anymore. I had smog legal mids on the V6.

I don't share the opinion that shorties are worthless. But yes, they are pretty much your only option.
If he's talking about the 97 SS, than ANY headers other than shorties will move the cat. 96-97 cars have 2 cats.

Yep, that's why I didn't even address mid-length headers.

For 1, I only know of AS&M mid-lengths for the LT1 (which I have), and 2) all the AS&M headers are single-cat now... so you have to convert to a 94-95 style path/cat-location.

AS&M's obviously won't pass visual inspection in the Republik of Kalifornia.

At one time I belive AS&M actually HAD a dual-cat design for 96-97 cars... but demand was low since the single-cat version flowed better and they dropped it many years ago... and I belive it was only a mid-length on the passenger side, with the driver's side being a shortie-style keeping the cat up top near the stock location. :p

Go with SLP shorties and be happy with your new-found plug access and hp gains. Besides... once you go turbo you'll need shorties anyway. :)

AS&M had a set of CARB dual-cat headers, but they had major problems with the heat melting everything in the engine compartment, becasue of the way the driver's side primaries had to wrap up over the valve cover to keep the drivers side cat in the stock location. I think that's why they stopped making them.

A buddy of mine bought a used set of the AS&M dual-cat headers for his 97 Z28. They came with a complete firewall heat shield pad. We added shiedling to the heater box. They still melted stuff in the engine compartment, like the plastic dipstick handles.

The guy pulled the AS&M's out, and junked them. He contacted a friend at SLP, and bought a set of extrude honed LT1 exhaust manifolds. I think SLP had them made for the LT4 97 F-Bodys (not sure if they actually installed them). He was very happy with the extrude honed stockers, but I don't think he ever dynoed them.

Good to hear, I guess its still an option.

I remember an article out of CAMARO saying they only added about 3hp so they decided to scrap that idea. I've always thought they were intending to use those on the 1996 SLP cars, and LT4's but ditched them at the last minute. I've seen the extrude hone as an SLP option from a dealer sticker on an 96 SS I was going to buy though :shrug:

The cost/benefit was to high so they dropped them I imagine. I still think there are some SLP cars out there that may actually have them though as a stock option, and SLP just sold the extra's online... :)

I still have my SLP LT4 exhaust manifolds, but I've put headers on since. If I had my to do-over, I would have left them on instead of investing in the shorties.

They are stainless steel and are port-matched to my LT4 heads. My LT4 setup.. hotcam, heads, exhaust and intake manifolds etc., pulled 349 RWHP with a stock tune.

Were they stock on your car? Or did you add them yourself when SLP was selling them online?

I added them aftewards. The stockers have flashing and otherwise rough internal casting anomalies, along with being cast iron. The SLP LT4 exhaust manifolds are very smooth inside.

There is an Extrude Hone company in Huntington Beach near my city. I was thinking aobut calling them up and getting a quote.

If you get a quote please share. I'm curious to see what they would charge.

depends on the place, but http://www.gethoned.com/price_list.php# charges ~$700 for V8 manifolds.

Headers are cheaper.

Plus... headers are proven hp, where results from extrude honing seems to range from nothing to a few ponies.

On a side note, you CAN extrude hone your headers... I've read NASCAR, F1, and many other high-cost teams use it to knock out the carbon after a few races and probably helps clean up the welds inside custom tubes as well.

Not a bang-for-the-buck option IMO... but if you can get the LT4 ones from SLP it may be comparable to shorties, just with a few less ponies and crappy plug access.

Yeah, there's no point really imo to go ahead and have your manifolds extruded honed, gains are less than minimal.