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LT headers worth it on an L98

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Old 03-13-2018, 12:47 AM
  #21  
aklim
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Originally Posted by GREGGPENN View Post
I like the idea of improving the intake too...whether just the tubes or a superram. Without a cam change, these two mods might run fine w/o a tune -- though it never hurts to get TunerPro to see what's going on. TunerPro is a good tool for general diagnosis as well...and is cheap.
MAYBE it is because I was speed density and it didn't like the changes but my F-body did have hesitation issues with the Superram and LPE Tri-Y headers till they returned the chip. Do you know if the F-body had a different cam? I know it had iron heads. Is the F-body L98 that different from a Y-body L98?
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Old 03-13-2018, 03:47 PM
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I think it's because the MAF setup prior to 90 was more forgiving.

FP increase might help too...as many have noted in other threads. Personally, I've always been a bit surprised when people say more FP helps (stock cars). From what I've seen in the stock tune(s) posted online (and as I used as a starting point for my mods), it's already pretty rich. Though, not so rich as to fall outside correctable range. Maybe that's what people like as a result....better tip-in? As WOT, more fuel might also provide better torque at the expense of HP....but who's looking for HP on an L98?!?!
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Old 03-13-2018, 05:14 PM
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The best way to port L98 manifolds is to replace them with LT1 manifolds. They're not long tubes, but the difference between the L98 and LT1 manifold is significant
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Old 03-13-2018, 05:21 PM
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If doing this again, I would be very tempted to start with something like this (with the manifold down pipes) or equivalent:

http://pypesexhaust.com/i-12200821-8...em-scc40r.html

http://pypesexhaust.com/i-12200746-8...pes-dcc40.html

Gotta admit that I don't like the tips, but it does sound good in the video.

Note: I gained nothing by adding lpe 1 5/8" long tubes and an x-pipe to a pre-existing 2 1/4" true dual system without cats. Car was already in the mid-13s at this point in time with and without long tubes.

I think replacing the rest of the exhaust first is the way to go on an L98. Can always easily add long tubes later if you really want them.

Last edited by tequilaboy; 03-13-2018 at 05:26 PM.
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Old 03-13-2018, 05:34 PM
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Originally Posted by vette196 View Post
The best way to port L98 manifolds is to replace them with LT1 manifolds. They're not long tubes, but the difference between the L98 and LT1 manifold is significant
Did the EGR hook up too? I suppose if not you can blank out the EGR code and remove the problem part? Assuming you do not have the smog **** state bothering you.
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Old 03-13-2018, 05:37 PM
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Originally Posted by aklim View Post
Did the EGR hook up too? I suppose if not you can blank out the EGR code and remove the problem part? Assuming you do not have the smog **** state bothering you.
The ones that were installed had a big brass screw blocking the hole
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Old 03-13-2018, 06:12 PM
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Originally Posted by vette196 View Post
The ones that were installed had a big brass screw blocking the hole
But would it have lined up for installation with the EGR stuff? Just curious
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Old 03-13-2018, 11:10 PM
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Originally Posted by aklim View Post
But would it have lined up for installation with the EGR stuff? Just curious
LTx manifolds have the EGR fitting in a different location. If you wanted EGR function, you'd have to fab something up (to replace the EGR pipe). L98s have the EGR manifold fitting ONLY in the PS. LTx have a fitting on both sides.

For appearance sake, shorties would look better than LTx manifolds...specifically because of the EGR fittings. Sometimes they cost nearly as much as longtubes though. There's been a set of shorties in C4 parts for months and months but the price is too close to long tubes. Mid 2017, I remember someone ported a stock set of L98 manifolds then had them coated. They were priced right. I assume they were sold.

I like the look of those OBX headers for a stock motor w/o much else being modded. Obviously mixed feedback -- but so were the "custom" headers I bought back in 2007. Once all was said/done, I considered the feedback (including my own) a bit too whiney. They weren't "bolt-on" like TPIS but I enjoyed the bracketology. Really surprising considering my install wasn't during March Madness!
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Old 03-14-2018, 10:28 AM
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Originally Posted by aklim View Post
But would it have lined up for installation with the EGR stuff? Just curious
He deleted all of the emission stuff and the LT1 manifolds came with the brass bolt already in the EGR hole
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Old 03-14-2018, 10:58 AM
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Originally Posted by vette196 View Post
He deleted all of the emission stuff and the LT1 manifolds came with the brass bolt already in the EGR hole
Then it's all good if he doesn't have to pass visual emissions or better yet, emissions as a whole.
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Old 03-15-2018, 01:14 AM
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Default You're getting a lot of comments but...

You might want to get a copy of John Lingenfelters book on modifying the small block Chevy. He makes an interesting comment about the tubes that came on the L98s Vs long tubes.
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