When do the stock valves become a restriction?
Sep 20, 2015, 05:43 PM
#1
When do the stock valves become a restriction?
2.0
standard rod length turbo tuffs
10.5:1 compression wiseco 1400hd
mivec head
GSC S3s
Kiggly beehives
T3 super 99
At what point will my stock valves and stock head porting become a restriction? Head is already on the block, debating on taking it off for oversize valves and porting. Anyone been over 900 hp on stock sized valves?
standard rod length turbo tuffs
10.5:1 compression wiseco 1400hd
mivec head
GSC S3s
Kiggly beehives
T3 super 99
At what point will my stock valves and stock head porting become a restriction? Head is already on the block, debating on taking it off for oversize valves and porting. Anyone been over 900 hp on stock sized valves?
Sep 21, 2015, 08:26 AM
#3
EvoM Guru
iTrader: (1)
When do the stock valves become a restriction?
Your head is a restriction on that setup. So is the stock intake mani and TB..
Sep 21, 2015, 12:38 PM
#4
The Evo X head has bigger intake valves (35mm vs 34mm) than the Evo 8/9 and smaller exhaust valves (29mm vs 30.5mm). So, you may want to consider doing what Mitsubishi engineers decided for the Evo X.
If you're running a super-huge (800whp+) turbo, then the rules change further.
If you're running a super-huge (800whp+) turbo, then the rules change further.
Sep 21, 2015, 12:55 PM
#5
EvoM Guru
iTrader: (1)
The head needs ported, plain and simple. A magnus IM or ported skunk2 IM should also be on that motor. With that turbo, you're going to want to rev that thing deep into the 9k range, and maybe even touching into the 10k range. A stock head and stock (even if ported) IM will not support that. I hope you put the hardware in the bottom end to do it, IE mains studs upgraded rod bolts (better than the standard ARP 2000's), as well as higher end head studs (L19's or 625+). I hope the rotating assembly and clutch/flywheel are all balanced as well.
Sep 21, 2015, 02:04 PM
#6
To gain an understanding of what this means in real-world terms, you might want to read these:
https://www.evolutionm.net/forums/au...cnc-heads.html
https://www.evolutionm.net/forums/au...0whp-gain.html
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Sep 21, 2015, 05:43 PM
#8
The head needs ported, plain and simple. A magnus IM or ported skunk2 IM should also be on that motor. With that turbo, you're going to want to rev that thing deep into the 9k range, and maybe even touching into the 10k range. A stock head and stock (even if ported) IM will not support that. I hope you put the hardware in the bottom end to do it, IE mains studs upgraded rod bolts (better than the standard ARP 2000's), as well as higher end head studs (L19's or 625+). I hope the rotating assembly and clutch/flywheel are all balanced as well.
Sep 21, 2015, 05:46 PM
#9
EvoM Guru
iTrader: (1)
I would port the head. You'll be leaving a lot on the table if you don't..
Sep 21, 2015, 05:47 PM
#10
The capabilities of the stock valve sizes exceed the capability of the factory ports/bowls. The factory head is nothing special when it comes to flow potential. It presents a restriction to everyone who is interested in more power. The greater the power target, the greater the drawbacks of the factory head.
To gain an understanding of what this means in real-world terms, you might want to read these:
https://www.evolutionm.net/forums/au...cnc-heads.html
https://www.evolutionm.net/forums/au...0whp-gain.html
To gain an understanding of what this means in real-world terms, you might want to read these:
https://www.evolutionm.net/forums/au...cnc-heads.html
https://www.evolutionm.net/forums/au...0whp-gain.html
Sep 21, 2015, 05:52 PM
#11
EvoM Guru
iTrader: (1)
Those CNC heads are real nice, I knew there was power being left on the table with stock ports and valve sizes was just trying to gauge how much it will really effect it. I wish I had the money for a CNC head but that is simply just out of my budget. I've always heard good things about Curt Brown heads, any other places I should consider?
Sep 21, 2015, 06:49 PM
#12
CNC heads are expensive, but they deliver. It wasn't in my budget either until I observed third-party flow data from some of the hand-ported heads being sold around here, including one that I owned. I had no trouble making my decision after that. Regarding the budget, just keep in mind that where you want to go is expensive territory.
Sep 21, 2015, 07:01 PM
#13
Here is a clear answer. NO you don't need over size valves or porting. I am currently running stock size intake valves, stock exhaust valves and a stock head that is not ported. I have ran as fast as 177mph with this setup. I would guess its making 1000+hp . Also have seen 11k+ rpm and my average gear change is at 10,800rpm.
I will say it took about 5psi more to achieve those numbers compered to a fully ported head with oversize valves. Remember boost is a measurement of restriction.
Long story short there are gains with good port work and over size valves but you can spin 10k+ and make 1000+hp without it.
I will say it took about 5psi more to achieve those numbers compered to a fully ported head with oversize valves. Remember boost is a measurement of restriction.
Long story short there are gains with good port work and over size valves but you can spin 10k+ and make 1000+hp without it.
Last edited by gr8stevo; Sep 21, 2015 at 07:04 PM.
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Dec 3, 2015, 10:21 PM
#14
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Here is a clear answer. NO you don't need over size valves or porting. I am currently running stock size intake valves, stock exhaust valves and a stock head that is not ported. I have ran as fast as 177mph with this setup. I would guess its making 1000+hp . Also have seen 11k+ rpm and my average gear change is at 10,800rpm. I will say it took about 5psi more to achieve those numbers compered to a fully ported head with oversize valves. Remember boost is a measurement of restriction. Long story short there are gains with good port work and over size valves but you can spin 10k+ and make 1000+hp without it.
Feb 21, 2021, 11:24 AM
#15
🙏
Here is a clear answer. NO you don't need over size valves or porting. I am currently running stock size intake valves, stock exhaust valves and a stock head that is not ported. I have ran as fast as 177mph with this setup. I would guess its making 1000+hp . Also have seen 11k+ rpm and my average gear change is at 10,800rpm.
I will say it took about 5psi more to achieve those numbers compered to a fully ported head with oversize valves. Remember boost is a measurement of restriction.
Long story short there are gains with good port work and over size valves but you can spin 10k+ and make 1000+hp without it.
I will say it took about 5psi more to achieve those numbers compered to a fully ported head with oversize valves. Remember boost is a measurement of restriction.
Long story short there are gains with good port work and over size valves but you can spin 10k+ and make 1000+hp without it.