C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

CARB legal L98 headers

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Old Jul 18, 2001 | 11:04 PM
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I'm sure this has been asked before, but I haven't had any luck finding CARB legal headers for a 90 L98. The other question is would there be enough benefit? I plan some serious mods in the future (I have many SBC race parts, 400 short blocks, etc.), but since I live in the police state of CA everything I do, that is visible, has to pass smog inspection.

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Old Jul 18, 2001 | 11:19 PM
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Thats because they dont exist. Trust me, no matter what anyone says, they don't exist. You can get ones that have all the smog hookups, but no carb #. I am hoping that wath all the smog stuff hooked up, some moron will let it through since there are many smog legal headers, just not for us.

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Old Jul 18, 2001 | 11:33 PM
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Couldnt find any when i was looking!
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Old Jul 19, 2001 | 02:15 AM
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Another idea: Maybe it is possible to modify an LT1 complete system and bolt it up. Most smog check people would not know the difference as long as they look right and have an EO number. Anyone ever look into this? The only other options I've thought of would be swapping the stock system on and off every two years, or getting the stock manifolds extrude honed.

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Old Jul 19, 2001 | 04:09 PM
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Why is the c-k being filtered?

________________________________________ __

I was looking into doing this as well, also had a few Emails with Vash/(Kale) about it which has had me thinking.

I have been looking around, I see the LT1 systems which look like the L98's, except for the emissions stuff. So I figure you weld on the emmisions stuff and it should look st-o-c-k to the average joe.
In this case, I dont think you would need the EO#'s, and I would try to hide them mainly because I thought EO#'s went along with a year that they are for?

If you got cermic coated shorties I think they would catch the smog guys eye. Dont know if that would be good or bad. I think I would get bla-c-k shorties and force fit the st-o-c-k heat shelds on them if I were going to do this, to fully pull off the scam.

The L98's exhuast manifolds look like it has 1 to 1.25" primaries tubes. I tried to open all mine up, I may of took as much as 1.5" tubes on 2-3 of em. I was worried about the weld because they are on the inside's of the tubes so I stopped there.

The LT1 aftermarket systems have 1 5/8 primaries and would be nice on a modded L98, match that up with 2.5" pipes and high flow cats, instead of the st-o-c-k 2.25" and I think you would have a decent exhuast system, asuming you have a few mods to breath in the upper rpms.

Something I noticed looking at LT1 shorties, they dont have the exhaust bolt spacers welded on in the pics I have seen. You need these to use the st-o-c-k exhuast bolts. This means you have to use header bolts. I hate header bolts and find them to be a total PITA! Maybe these pics were not correct, but that is something to consider as well. For this reason alone I payed more $$$ for the TPIS headers with the spacer attached. (yes, I am a headers user)

the other alternative, try and find a guy to clone your st-o-c-k manifolds using bigger tubes.

[This message has been edited by bill mcdonald (edited 07-19-2001).]

[This message has been edited by bill mcdonald (edited 07-19-2001).]

[This message has been edited by bill mcdonald (edited 07-19-2001).]
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Old Jul 19, 2001 | 05:10 PM
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Does the '90 still have pre-cats? You gonna weld those on?
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Old Jul 19, 2001 | 05:25 PM
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Get in touch with Edelbrock and see if their TES will fit, they have a CARB number.

I recently heard that Random Tech makes now a 3-stage hi-flow cat to replace the precats and the main cat.

Maybe we should pressure TPIS to get their headers CARB certified. It would be to their benefit as more states get pickey about this stuff.


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Old Jul 19, 2001 | 05:39 PM
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Thanks for the info. I'm going to see what I can come up with. I wish it was easier. It seems like there must be others out there facing the same issue. If I find a good solution I'll let you know what it is.

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Old Jul 19, 2001 | 06:03 PM
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The '90 has pre cats, I dont think I am going to put them on. I havent decided what to do yet, headers are sitting in the box still.

I had hedmen headers on there before, no cats at all with true duals. I pulled it to pass smog, and have been stock since.
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Old Jul 19, 2001 | 08:07 PM
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Originally Posted by 65Z01
Get in touch with Edelbrock and see if their TES will fit, they have a CARB number.[/color]
CARB# is vehicle specific. Yes the TES have a carb but not for a vette. Doesn't mean it wouldnt pass a dumb inspector, but I don't know it they fit either.
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Old Jul 20, 2001 | 04:57 AM
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In that case our only option is to convince TPIS or someone to qual their headers with a CARB number. Once one MFG does it you'll see others follow to stay competitative.

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Old Jul 20, 2001 | 11:44 AM
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If I understood the rule book correctly, if you have a mod or component that is not CARB certified, you can take it to a referee station and if you pass emmissions then they will certify your car. Has anyone tested the rule book? (the rule book is online I just can't remember what the link was)
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Old Jul 20, 2001 | 12:27 PM
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Hi

I am fairly new here but my car uses the stock tubular headers. It sounds awesome and the numbers speak for themselves. Dyno in the next 2 weeks, but it is just as strong as a ZR-1 I drove under WOT.

I would have your heads ported and maybe your headers extruded?

Just an idea...

Rich

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Old Jul 20, 2001 | 01:21 PM
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87ZZ4 - Please post the dyno numbers when you get them. I opened up my stock manifolds as much as possible and still only got 1.3" ID. Plus, the bends are so restrictive. I ran over budget and haven't put together the money for my exhaust, so I'm basically running a stock exhaust minus cats and it has negated everything I've done to the motor. The top end flow and power range just don't work with that exhaust on my setup. Oh well, back to topic

2many - I think your best bet would be to bend up some stock looking manifolds. I'd like to move to California, but CARB is the main reason I stay away.
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Old Jul 20, 2001 | 01:35 PM
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It looks like the best way to solve this is to swap the stock system in and out every two years. In the mean time I will run something that has all of the emissions connections and keep them from being too flashy. I can live with that I guess... I think CARB is a bad deal. Passing the specs is really what matters, but not to CARB.

Thanks for all the info

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