over sized valves are they worth the extra effort +money
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ONPSI
10 second monster
Are you building a full engine or just looking to do an upgrade? If your trying to get everything you can out of the engine and big hp i would say yes
BMGTZ
Grumpy old man from the school of hard knocks
In my opinion yes....why....they can provide the benifits of a cam upgrade without the idle attracting unwanted attention. The cam holding the valve open longer....where as the valve being bigger allows more flow straight off the bat
I have used 1mm oversize and 264 exhaust cam.....big difference
I have used 1mm oversize and 264 exhaust cam.....big difference
CYBORG-X
Well-Known Member
with the oversize, you can get a nice 7 angle valve job done.... unlike the shit factory 3 angle....
4piknup
master of none
It will make a bigger % improvement without those other bits as bigger valves help with low lift flow more than high lift flow that is governed more by port size.
I definitely getting them for the 2.4 as there is a larger bore that won't shroud the valves
Agree - it would be a worthwhile thing to do if you had the opportunity. I was just weighing up the cost vs benefit side of things and in my case it wasn't worth the cost for the benefit. When I build up my 2.4 (at some stage) I'll certainly be pulling out all the stops to try and extract as much from the setup as possible.
Ask yourself these questions....
* Is changing from an OEM exhaust to a 3" worth the extra effort and money? If it is, how much more power does it give you?
* Is changing the OEM cams to 264's or 272's etc worth the extra effort and money? If it is, how much more power does it give you?
* Is changing the OEM ECU and AFM to a programmable ECU worth the extra effort and money? If it is, how much more power does it give you?
* Is changing the OEM intercooler, piping and intake manfold worth the extra effort and money? If it is how much more power does it give you?
* Is changing the OEM turbo to a 20G or bigger worth the extra effort and money? If it is, how much more power does it give you?
If you answered 'yes' to all the above then the original question is a retorical one lol
Basically each item may make a small or noticable impact on its own, but together as an accumulation they have the potential to significantly make a massive difference to what you first started out with.
The same goes with the oversize valves. Its just another mod that falls within the above price range that can help add some more ponies to your overall package.
Shayne, even though you'll still notice a difference if you're running low duration low lift cams, the benefits wont be much going oversize valves alone. However the most gains are made by how much air/fuel you can squeeze into the combustion chamber during the time the valve is open. So yeah, big boost, high lift long duraton cams, ported intakes and oversize valves all help with airflow. Note that this is also the extreme end of the scale when you're trying to squeeze the most power you can out of the engine. Dont let somebody convince you that you shouldnt fit 1mm oversize valves unless you're at the latter end of the scale because its bullsh!t. There's a whole lot of ground in between where gains can and will be made by installing them, for the same costs as, plus similar gains as the items I first listed above.
* Is changing from an OEM exhaust to a 3" worth the extra effort and money? If it is, how much more power does it give you?
* Is changing the OEM cams to 264's or 272's etc worth the extra effort and money? If it is, how much more power does it give you?
* Is changing the OEM ECU and AFM to a programmable ECU worth the extra effort and money? If it is, how much more power does it give you?
* Is changing the OEM intercooler, piping and intake manfold worth the extra effort and money? If it is how much more power does it give you?
* Is changing the OEM turbo to a 20G or bigger worth the extra effort and money? If it is, how much more power does it give you?
If you answered 'yes' to all the above then the original question is a retorical one lol
Basically each item may make a small or noticable impact on its own, but together as an accumulation they have the potential to significantly make a massive difference to what you first started out with.
The same goes with the oversize valves. Its just another mod that falls within the above price range that can help add some more ponies to your overall package.
Shayne, even though you'll still notice a difference if you're running low duration low lift cams, the benefits wont be much going oversize valves alone. However the most gains are made by how much air/fuel you can squeeze into the combustion chamber during the time the valve is open. So yeah, big boost, high lift long duraton cams, ported intakes and oversize valves all help with airflow. Note that this is also the extreme end of the scale when you're trying to squeeze the most power you can out of the engine. Dont let somebody convince you that you shouldnt fit 1mm oversize valves unless you're at the latter end of the scale because its bullsh!t. There's a whole lot of ground in between where gains can and will be made by installing them, for the same costs as, plus similar gains as the items I first listed above.
I remember reading something along the lines that; if you put in oversize valves without the right head port work leading up to the larger valve, you will actually loose flow.
If I remember right it had something to do with, if the port is not opened up to the larger valve, a larger cross section of air can not get to the larger valve anyway, so now you have created 1mm larger valve the air has to curve past to enter the cylinder.
Anyone heard of this?
If I remember right it had something to do with, if the port is not opened up to the larger valve, a larger cross section of air can not get to the larger valve anyway, so now you have created 1mm larger valve the air has to curve past to enter the cylinder.
Anyone heard of this?
Around 13 years ago (i know, im an old fart)on a stock big port head I made 320 kw at the wheels, with a port job bigger valves, 272 cams, valve springs etc, I made
370 odd kw on the same boost(30 psi), but it did change the powerband to later in the rev range.I had to rev it to 8500 to make the power.
After that I remember making 400kw at the wheels with a head that was ported and running stock valves, but with valve springs, 272 cams etc.
But I had to run alot more boost(+40psi).I ended up running ported head, with 1mm o/s valves, over 300 duration cams,all the good fruit
I made 480kw at the wheels on c16 and 28 psi, and 515 kw at the wheels on 32 psi.
On e85 it made 480 on 28 psi.
What im trying to say is on a budget head you can make 350-400 kw at the wheels if you are prepared to run a lot of boost, but the
downside is you might be driving a time bomb.If you invest a few thousand dollars more you can make the same power but
with a lot less boost and it will be much safer.
It will cost you more now but if set up right it will cost you a lot less in the future.
370 odd kw on the same boost(30 psi), but it did change the powerband to later in the rev range.I had to rev it to 8500 to make the power.
After that I remember making 400kw at the wheels with a head that was ported and running stock valves, but with valve springs, 272 cams etc.
But I had to run alot more boost(+40psi).I ended up running ported head, with 1mm o/s valves, over 300 duration cams,all the good fruit
I made 480kw at the wheels on c16 and 28 psi, and 515 kw at the wheels on 32 psi.
On e85 it made 480 on 28 psi.
What im trying to say is on a budget head you can make 350-400 kw at the wheels if you are prepared to run a lot of boost, but the
downside is you might be driving a time bomb.If you invest a few thousand dollars more you can make the same power but
with a lot less boost and it will be much safer.
It will cost you more now but if set up right it will cost you a lot less in the future.
4piknup
master of none
I agree with robevo.
I pretty sure they running mid 10s and better on standard valves. Plenty of boost tho
I pretty sure they running mid 10s and better on standard valves. Plenty of boost tho
Exactly, just because you 'could' do it, doesnt mean that you 'should' leave the oem valves in.
How reliable and how long do you think the OEM cast valves would last with the extra heat and stresses that more boost, higher rpm and lift/duration cams would put them under.
Jase, even if you decide not to go the 1mm oversize, IMO if you can afford to buy forged pistons and rods (stronger and lighter than OEM) to provide more reliability under higher boost, heat and rpm levels, then you should also anticipate to install ss valves as part of the package for exactly the same reasons.
How reliable and how long do you think the OEM cast valves would last with the extra heat and stresses that more boost, higher rpm and lift/duration cams would put them under.
Jase, even if you decide not to go the 1mm oversize, IMO if you can afford to buy forged pistons and rods (stronger and lighter than OEM) to provide more reliability under higher boost, heat and rpm levels, then you should also anticipate to install ss valves as part of the package for exactly the same reasons.
thats exactly right.It will bite you in the arse later on if you dont do it.
