'91 L98 Head Porting
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'91 L98 Head Porting
Not sure there is even any interest in this anymore. I recently purchased a 3rd Gen Camaro with a '91 L98 in it and decided to take the existing top end and rework it.
I started with the cylinder heads. I'm in the process of porting on them so I thought I would share..
First set of numbers are right off the car, to the bench.
Second set of numbers are the existing port shape just cleaned up and finished chamber with factory valve job and 1.94 valve
Third set of numbers are my custom multi-angle cutter and 1.94 valve
I'm going to use a 8mm 2.00/1.57 LS valve and LS spring kit.
I will post as I go if interest!!
I started with the cylinder heads. I'm in the process of porting on them so I thought I would share..
First set of numbers are right off the car, to the bench.
Second set of numbers are the existing port shape just cleaned up and finished chamber with factory valve job and 1.94 valve
Third set of numbers are my custom multi-angle cutter and 1.94 valve
I'm going to use a 8mm 2.00/1.57 LS valve and LS spring kit.
I will post as I go if interest!!
Last edited by Chad Speier; Nov 10, 2018 at 10:35 AM.
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
Looks like the chambers have had some massaging, Nice improvement over stock so far
Many underestimate what the right valve job can do , maybe you could elaborate.
Keep it coming!
Many underestimate what the right valve job can do , maybe you could elaborate.
Keep it coming!
Last edited by cv67; Nov 10, 2018 at 11:51 AM.
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Melting Slicks
Joined: Nov 2013
Posts: 3,451
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From: Greater Cincinnati Area.
Pardon my ignorance, but you didn't reshape anything, right?
You're smoothing the valve guide and all the edges, but not re-engineering the port shape?
If so, that's a heck of an improvement just from cleaning it up.
You're smoothing the valve guide and all the edges, but not re-engineering the port shape?
If so, that's a heck of an improvement just from cleaning it up.
Last edited by confab; Nov 11, 2018 at 11:36 AM.
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More after a crisp sound than a 500hp engine.
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reshape might be the wrong word. I haven't moved any wall yet.
But yes, it responded and after you see the nastiness of the OEM port, it's easy to see why.
Melting Slicks
Joined: Nov 2013
Posts: 3,451
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From: Greater Cincinnati Area.
Cool...
This stuff is very interesting to me. I just bought a set of SLP Runners and a Plenum from the used section yesterday, and I've been looking into porting and port matching.
Wondered if it was worth bothering with.. But those numbers are fantastic. As much flow at .300 as the stockers had at .700!
That was totally worth doing.. Thanks for posting. Keep going!
This stuff is very interesting to me. I just bought a set of SLP Runners and a Plenum from the used section yesterday, and I've been looking into porting and port matching.
Wondered if it was worth bothering with.. But those numbers are fantastic. As much flow at .300 as the stockers had at .700!
That was totally worth doing.. Thanks for posting. Keep going!
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I'm going to say confidently GM was in the weeds on the bottom manifold. Head is 1205ish and the manifold is 1204ish and couldn't go 1205 without weld. It's getting .300 on all the tops start to finish.
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But no matter what, even with big tube, it's still going to peak low because of the total length.
Last edited by Chad Speier; Nov 11, 2018 at 11:00 PM.
