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TEA inflates the exhaust numbers by using a pipe. So it's good for comparison between TEA products. And that's about it.
It's not helpful because you don't know the true E/I ratio on the heads. They are not 75% efficient tho. They are probably more like 65%... which means they will want a lot more exhaust duration.
And to Martin's point on the TFS 245s... the Coefficient of Discharge is much better on the 245s. They flow nearly what the 255s flow under 600 but use a much smaller valve to get there. So they are a more efficient head. Where the 255s make a hell of a lot of sense is if you do a LLR and aim for .700" lift or more. And using a roller rocker on a head allows you to have a true 1.7:1 or 1.8:1 ratio throughout the lift range. The stock rocker is more like a 1.4 or 1.5:1 ratio at low lifts. So it doesn't help. You see the increase in power moving to a 1.8:1 ratio on stock cams and it's because duration and lift are increased across the range. But why don't you see on the hotter setups? Easy. The valve springs aren't enough to control the valve and heavier rocker with more extreme lobe profiles. Adding more spring doesn't always help because you still have a hydraulic roller lifter that can collapse as the RPMs rise. How do you eliminate that?
Martin Here are the flow numbers I just received with my sons heads !
They are TFS 255 from TEA .
Those numbers are about 5 better across the board than I have on my spread sheet for the TEA 255's. They are actually 2-4 numbers higher from .100-.300 than the TFS 245 head, again based on the numbers I've accumulated through the years. So with those numbers in mind, you would want 1-3 degrees less overlap with these TEA 255 heads than a TEA 245 cathedral head on the same engine.
TEA inflates the exhaust numbers by using a pipe. So it's good for comparison between TEA products. And that's about it.
It's not helpful because you don't know the true E/I ratio on the heads. They are not 75% efficient tho. They are probably more like 65%... which means they will want a lot more exhaust duration.
And to Martin's point on the TFS 245s... the Coefficient of Discharge is much better on the 245s. They flow nearly what the 255s flow under 600 but use a much smaller valve to get there. So they are a more efficient head. Where the 255s make a hell of a lot of sense is if you do a LLR and aim for .700" lift or more. And using a roller rocker on a head allows you to have a true 1.7:1 or 1.8:1 ratio throughout the lift range. The stock rocker is more like a 1.4 or 1.5:1 ratio at low lifts. So it doesn't help. You see the increase in power moving to a 1.8:1 ratio on stock cams and it's because duration and lift are increased across the range. But why don't you see on the hotter setups? Easy. The valve springs aren't enough to control the valve and heavier rocker with more extreme lobe profiles. Adding more spring doesn't always help because you still have a hydraulic roller lifter that can collapse as the RPMs rise. How do you eliminate that?
Solid roller.
Remember though, the engine is running with a "pipe" on the exhaust so it is actually somewhat realistic. Although I know several head porters that don't even flow their exhaust ports because you cannot accurately simulate the pressures seen on a running engine in the exhaust port on a flow bench.
I was mainly just speaking on low lift flow and how it correlates to overlap, but yes you're also correct on the COD.
As you mentioned though, in this comparison the 255's need .700+ lift to really shine.
Those numbers are about 5 better across the board than I have on my spread sheet for the TEA 255's. They are actually 2-4 numbers higher from .100-.300 than the TFS 245 head, again based on the numbers I've accumulated through the years. So with those numbers in mind, you would want 1-3 degrees less overlap with these TEA 255 heads than a TEA 245 cathedral head on the same engine.
Is this going to work with the cam you specked for me ?
Martin what's your thoughts of using the stage 2 cam on a set of ported stockers? Car is an auto with a yank 3600ss converter
Well, technically if you ordered it from me it wouldn't be a "Stage 2"...technically.
The 229/244 112+4 works very well. I started to use this cam in late 2012, early 2013. It is a great all around camshaft for a street car that doesn't want to sacrifice a ton of bottom end as a larger camshaft would, but still holds it own with the larger cams at higher RPM.
Remember though, the engine is running with a "pipe" on the exhaust so it is actually somewhat realistic. Although I know several head porters that don't even flow their exhaust ports because you cannot accurately simulate the pressures seen on a running engine in the exhaust port on a flow bench.
I was mainly just speaking on low lift flow and how it correlates to overlap, but yes you're also correct on the COD.
As you mentioned though, in this comparison the 255's need .700+ lift to really shine.
That's true. But it still props up the exhaust. If I believe the numbers TEA gave me, I'm at an 85% efficient head. And it's not. LOL
My build with MAMOFIED TFS LS3 255s employed a LLSR
with "Only" .680"/.645" lift, & "Only" +6* exhaust split
243*/249* with 115*+3* very happy with my results
690 Crank HP 7100-7300 & carry to 7600+ from
396" @ 11.7:1 Comp. I would be interested in Martins
Comments on my results "violating conventional wisdom"
Regarding cam specs for these heads.
Well, technically if you ordered it from me it wouldn't be a "Stage 2"...technically.
The 229/244 112+4 works very well. I started to use this cam in late 2012, early 2013. It is a great all around camshaft for a street car that doesn't want to sacrifice a ton of bottom end as a larger camshaft would, but still holds it own with the larger cams at higher RPM.
which sounds about what I'm wanting. Car mostly sees street action with the occasional weekend trip to the track. I plan on keeping the stock LS3 intake also for now. I'm not looking for a huge peak dyno # but a car with great usable power all around
Personally I would go cathedrals. It's a stock bottom end LS3 here on board with some TFS BTR 220s running 10s with a 6 speed naturally aspirated and the car is full weight 4th gen SS. Think the member name is SilverLSwon.
The TFS 255 heads out the box isn't worth the money. I've seen 7 hp difference between a cnc LS3 factory head vs a TFS 255 head out the box. Sorry but im not paying 1200 dollars for 7 horsepower.
Personally I would go cathedrals. It's a stock bottom end LS3 here on board with some TFS BTR 220s running 10s with a 6 speed naturally aspirated and the car is full weight 4th gen SS. Think the member name is SilverLSwon.
The TFS 255 heads out the box isn't worth the money. I've seen 7 hp difference between a cnc LS3 factory head vs a TFS 255 head out the box. Sorry but im not paying 1200 dollars for 7 horsepower.
there's a couple other things I need so for now I'm gonna go with a set of ported stock heads for half the price and I'm leaning towards the Tick stage 2 cam. I've seen great results with that cam posted on several places
Here's the flow #'s for the PRC ported stock heads if that helps which is more than likely the heads I will be going with. Seem like a good deal for a budget head. $1300 without springs. I already have a good set of BTR .660 springs to use
04-13-2017, 08:16 PM
