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New 90MM 8.1L Intake Manifold

Old 04-06-2014, 07:38 AM
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Originally Posted by Raylar Engineering
We ran all of our manifolds on Sunday and learned a few things. The cool gap manifold, with it's longer runners made slightly more torque than the shorter runner new prototype manifold. However, the shorter runner manifold really takes off past 4500rpm, and it makes more power than the cool gap by 5400-5500 rpm.

The modified stock manifold produces great torque and midrange, but even with all the modifications we make to it starts to fall off around 5200 rpm.

The motor we used was a marine engine so it's rev limiter was (non-adjustable) set at 5400-5500 rpm, so we don't have a really good idea yet of where the short runner prototype manifold falls off, but we're guessing around 6200-6400 rpm based on what we saw. We'll be running more tests with the 540 engine soon to see what's possible with a street motor.
Same issue I had with the one I made engine loves the long runners. twin turbos forcing air into it may be an interesting test.
Old 04-18-2014, 09:31 AM
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I think this about solidifies my plan to swap to a 540ci 8.1. My modded TBI runs stronger than a new stock 8.1 Burb but at that, the TBI is tapped out. Also, this OBD1 computer bullshit is for the birds, it might be cheap but that's about the only advantage I see.
Old 04-18-2014, 09:55 AM
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Originally Posted by 1BadAction
I think this about solidifies my plan to swap to a 540ci 8.1. My modded TBI runs stronger than a new stock 8.1 Burb but at that, the TBI is tapped out. Also, this OBD1 computer bullshit is for the birds, it might be cheap but that's about the only advantage I see.
I just did a 496 swap on a 1993 3500. And it runs mucho better then before. If you need help with swap info send me an email. Edward.coss@Gmail.com
Old 04-18-2014, 10:15 AM
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Originally Posted by xx_ED_xx
I just did a 496 swap on a 1993 3500. And it runs mucho better then before. If you need help with swap info send me an email. Edward.coss@Gmail.com
I'm just keeping my eye out for complete 8.1s with harnesses at this point so I can get it on a stand and start the tear down and build. My current engine build is 6000 miles old so I'm not in a big rush to get rid of it, but I do know the OBD1 just can't do what I want it to in the future.

I did finally get moved to Dallas, BTW.
Old 04-18-2014, 10:41 AM
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Are you in still in dallas might be able to hook you up with a setup
Old 04-18-2014, 10:46 AM
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Yep, Job, house, etc. I'm here for good as far as I know.
Old 04-18-2014, 10:47 AM
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I got a pull out with all accessories etc i may sell if you are interested
Old 04-18-2014, 10:55 AM
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Shot you a PM with some info.
Old 04-18-2014, 10:58 AM
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Texted ya
Old 04-18-2014, 12:45 PM
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Originally Posted by 1BadAction
I think this about solidifies my plan to swap to a 540ci 8.1. My modded TBI runs stronger than a new stock 8.1 Burb but at that, the TBI is tapped out. Also, this OBD1 computer bullshit is for the birds, it might be cheap but that's about the only advantage I see.
Pretty much. Dump the old motor, toss a stroker 8.1L in it with the 203 cam, iron head springs (if you're planning on keeping the stock heads), along with the ported intake manifold and go. Or, toss on the aluminum heads and make even more power.

The 540 suburban just got the ported manifold, made a huge difference over 3k! The power delivery doesn't end at 4k now, it pulls solid to 5500 or so. Also the exhaust note has changed at WOT. The engine sounds like its got a four barrel on it whereas before it sounded very... asthmatic / stock chevy truck. Dyno day is this week, I'll report back.

If I haven't already posted this, here's the baseline dyno video: 540 Stroker Kit Baseline Dyno

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