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What will this do for Horsepower increase..........

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Old Aug 9, 2013 | 11:02 PM
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Default What will this do for Horsepower increase..........

My forged iron 390ci. Right now it has my old LS1 ported heads that only flow 304cfm. Along with my LS6 intake. Stock ported TB.

If I swap those three with L92 ported heads that flow 350+cfm and a ported L76 intake and 90mm TB.......and a new cam to match.

What do you think I'll pick up for RWHP....?

It dynoed a little over 400 RWHP now. It's only 10.8:1 compression because its waiting for a turbo kit.

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Old Aug 10, 2013 | 10:23 PM
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That should be a substantial increase, like 10-15% or so.
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Old Aug 11, 2013 | 11:21 AM
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Give or take 420-430ish
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Old Aug 11, 2013 | 12:36 PM
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Originally Posted by xdanny510x
Give or take 420-430ish

You think that'll only be good for about 25 HP increase......?

What about the 1.5 HP increase per cfm increase. Just the heads alone should provide about 50 x 1.5 = 75 HP.........right?

Then with the supporting better intake and TB....maybe 10-15 more.???

People were getting 500 RWHP back in 2001-2002 with STOCK CUBES and head/cam kits........how were they doing it?
Like "Tomtheroofer" running 10 second 1/4 miles and over 500 RWHP......

Morgan Motorsports.....500 RWHP with their "500 Aggressor Head/Cam kit". Stock cubed engines.


HOW....?

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Old Aug 11, 2013 | 12:37 PM
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Originally Posted by San Diego Car Guy
That should be a substantial increase, like 10-15% or so.
That sounds more like it........

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Old Aug 11, 2013 | 05:30 PM
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Originally Posted by San Diego Car Guy
That should be a substantial increase, like 10-15% or so.
Somewhere around there^
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Old Aug 12, 2013 | 06:45 PM
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Originally Posted by Blackpanther99
Somewhere around there^
That's what I figured too.

Guess I'll slap the PRC 247's on.

What intake and TB do you think would best for my TT kit that's going on later..?

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Old Aug 18, 2013 | 04:37 PM
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L92 wont fit a 3.90 bore. Must be 4.0 or larger
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Old Aug 19, 2013 | 12:42 AM
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Originally Posted by my406cid
L92 wont fit a 3.90 bore. Must be 4.0 or larger
My 390ci is 4.030" bore.

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Old Aug 19, 2013 | 07:28 AM
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What about the 1.5 HP increase per cfm increase. Just the heads alone should provide about 50 x 1.5 = 75 HP.........right?
You are not going to see 75rwhp just from going from ported 241s to stock LS3s. And certainly not on a less than ideal 4.030 bore.

We don't know the cam you have now and the cam that you will go with the new heads to really say, but I would expect in the mid 400s at the wheels.
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Old Aug 21, 2013 | 12:20 PM
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Only one way to really know, do it and prove ppl wrong! lol
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Old Aug 30, 2013 | 01:43 PM
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Originally Posted by redtan
You are not going to see 75rwhp just from going from ported 241s to stock LS3s. And certainly not on a less than ideal 4.030 bore.

We don't know the cam you have now and the cam that you will go with the new heads to really say, but I would expect in the mid 400s at the wheels.
Just did one just like that with a Comp X281HR (alu block, not iron), each pull hit around 455-465 rwhp on E85 through a T56 with 3.5 rear end.

Build thread here: https://ls1tech.com/forums/conversio...r-ls-drop.html
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