Intake valves...2.00, 2.02, 2.04? Stock LS1 w/ big cam
10-12-2016, 10:45 PM
#1
Intake valves...2.00, 2.02, 2.04? Stock LS1 w/ big cam Trying to decide where to send a set of 243's to get worked. I am down to three companies, but i have a question about intake valve size:
I am getting new valves regardless, so what difference will 2.04 or 2.02 inake valves have over stock sized 2.00 valves?
More air, but less velocity?
For a stock LS1 shortblock, big cam, 1 7/8 headers, LSXR 90 right now, might go LSX 102 (throttle body is already 102mm).
I am getting new valves regardless, so what difference will 2.04 or 2.02 inake valves have over stock sized 2.00 valves?
More air, but less velocity?
For a stock LS1 shortblock, big cam, 1 7/8 headers, LSXR 90 right now, might go LSX 102 (throttle body is already 102mm).
10-13-2016, 10:23 AM
#3
Its all dependant on how your building your set up. being that it's a stock Short Block, I personally would just run the 2.02 valve.
You really should discuss your package with who ever you chose to get your heads ported with. Be realistic with your goals too when discussing your build with them. They will be better able to steer you in the right direction.
You really should discuss your package with who ever you chose to get your heads ported with. Be realistic with your goals too when discussing your build with them. They will be better able to steer you in the right direction.
10-13-2016, 10:26 AM
#4
More than likely, the best thing for me to do is to just get heads and a cam from the same place, to make sure I don't have PTV issues.
If I get a cam, I'm probably going with PRC stage 2.5 (2.02" intake valve) since they can match a cam that won't have PTV issues.
If I don't get a cam, I'm probably going with PRC stage 1 (2" intake valve).
Since I want new valves either way, the price difference is about $50.
10-13-2016, 10:54 AM
#6
Trying to decide where to send a set of 243's to get worked. I am down to three companies, but i have a question about intake valve size:
I am getting new valves regardless, so what difference will 2.04 or 2.02 inake valves have over stock sized 2.00 valves?
More air, but less velocity?
For a stock LS1 shortblock, big cam, 1 7/8 headers, LSXR 90 right now, might go LSX 102 (throttle body is already 102mm).
I am getting new valves regardless, so what difference will 2.04 or 2.02 inake valves have over stock sized 2.00 valves?
More air, but less velocity?
For a stock LS1 shortblock, big cam, 1 7/8 headers, LSXR 90 right now, might go LSX 102 (throttle body is already 102mm).
We have done a few of these combos lately for the stock bottom end guys.
10-13-2016, 11:12 AM
#7
One nice solution is to use the MAST Motorsports 11 degree heads. These heads have .100" more piston to valve clearance than a conventional LS head. You can even mill them some more to get more compression and still have ample valve clearance.
We have done a few of these combos lately for the stock bottom end guys.
We have done a few of these combos lately for the stock bottom end guys.
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10-13-2016, 11:20 AM
#8
Wherever you decide the send the heads, just have them give you the "valve-drop" measurement when complete. If you have that measurement we can create a custom camshaft for you to optimize your engine combo that will have sufficient valve clearance.
~Steven
10-13-2016, 10:56 PM
#10
Depending on how 2.04" intake valves affect air velocity, this looks like the TEA heads have the most velocity out of the three, above .2 lift.
10-14-2016, 10:43 AM
#11
Also, any of those head porter/suppliers can measure and tell you the "valve drop" measurement is on their heads. Find out what that is on both intake and exhaust valves and I can tell you what the valve clearance will be with a given camshaft. Or, create one.
10-14-2016, 05:00 PM
#13
I'd be curious how much of a power difference there would be between the 3.. I believe TEA is around 3-400 more than AI.. and AI is more expensive than PRC.. I'm curious which one would be a better bang for the buck. Plus what would AI flow with larger valves? All different flow benches too which doesn't help lol
10-15-2016, 07:40 PM
#14
TECH Addict
I, personally, think the TEA stage 2 heads would provide you with the most advantage. Even if it requires fly-cutting the pistons.
I feel that the large-ish ~230cc intake runner volume will allow you to use more of your large-ish ~230* intake duration cam, and allow adequate airflow higher into the rpms. Stepping up to a Fast102 would just further show this advantage, in my opinion.
And, the 2.04" intake valve is perfect for a 4.00" bore, if you ever step up to a 364-408 iron block. Once again, I feel the TEA stage 2 gives you the most room to grow.
I feel that the large-ish ~230cc intake runner volume will allow you to use more of your large-ish ~230* intake duration cam, and allow adequate airflow higher into the rpms. Stepping up to a Fast102 would just further show this advantage, in my opinion.
And, the 2.04" intake valve is perfect for a 4.00" bore, if you ever step up to a 364-408 iron block. Once again, I feel the TEA stage 2 gives you the most room to grow.
10-15-2016, 08:18 PM
#15
I'd be curious how much of a power difference there would be between the 3.. I believe TEA is around 3-400 more than AI.. and AI is more expensive than PRC.. I'm curious which one would be a better bang for the buck. Plus what would AI flow with larger valves? All different flow benches too which doesn't help lol
10-15-2016, 08:20 PM
#16
I, personally, think the TEA stage 2 heads would provide you with the most advantage. Even if it requires fly-cutting the pistons.
I feel that the large-ish ~230cc intake runner volume will allow you to use more of your large-ish ~230* intake duration cam, and allow adequate airflow higher into the rpms. Stepping up to a Fast102 would just further show this advantage, in my opinion.
And, the 2.04" intake valve is perfect for a 4.00" bore, if you ever step up to a 364-408 iron block. Once again, I feel the TEA stage 2 gives you the most room to grow.
I feel that the large-ish ~230cc intake runner volume will allow you to use more of your large-ish ~230* intake duration cam, and allow adequate airflow higher into the rpms. Stepping up to a Fast102 would just further show this advantage, in my opinion.
And, the 2.04" intake valve is perfect for a 4.00" bore, if you ever step up to a 364-408 iron block. Once again, I feel the TEA stage 2 gives you the most room to grow.
10-15-2016, 08:48 PM
#17
TECH Addict
Are you opposed to fly-cutting the pistons for the larger valves? In my opinion, people shouldn't be purposefully ruining LS1/6 blocks with boost or bottles anyways, so fly-cut stock pistons shouldn't pose any problems as far as durability or integrity are concerned. I understand that it is another expense and another process to schedule and wait for, but I think it is the best way to be able to use the best heads for this application, and the heads you want to use.
10-17-2016, 10:38 AM
#18
10-17-2016, 11:10 PM
#20
TECH Addict
Velocity is going to be determined a lot by the size/volume and shape/length of the intake runner, and the intake manifold design. You can have the airflow stall with big valves and/or small valves if the port is lazy.
Generally speaking, though, the larger valves increase curtain area. This the the umbrella of fuel/air that extends from around the valve as the valve opens. Larger valve diameter equates to a larger curtain area... pretty much more fuel/air per unit of valve lift, in juxtapose to a smaller valve.
Larger curtain area is generally always a good thing.
There are factors such as shrouding from the cylinder wall that effect how much additional curtain area you will experience when going up in valve diameter, but generally speaking the bigger valve usually wins when comparing flow due to the immediate mathematical increase in curtain area.
Generally speaking, though, the larger valves increase curtain area. This the the umbrella of fuel/air that extends from around the valve as the valve opens. Larger valve diameter equates to a larger curtain area... pretty much more fuel/air per unit of valve lift, in juxtapose to a smaller valve.
Larger curtain area is generally always a good thing.
There are factors such as shrouding from the cylinder wall that effect how much additional curtain area you will experience when going up in valve diameter, but generally speaking the bigger valve usually wins when comparing flow due to the immediate mathematical increase in curtain area.