afr vs. etp
Originally Posted by uberLS-1
I don't get it, you just suggested the least proven of all three? Why, got some hidden results somewhere?
For an all out NA typ app. then yes go with a head that has the last Nth of tricks up its sleeve to 'entice' the air into the engine.
There are plenty of turbo cars with just ported/valved 6L heads putting down >800whp. Save your money.
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6600 rpm clutch dump of death Administrator
Joined: Dec 2001
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From: Texas
Originally Posted by mr2guru
When you're not 'pulling' air into the engine anymore (boosted) head flow characteristics and intake characteristics become less of a concern. As for heads, what you need to look for is port volume and valve sizing. Let the turbo/supercharger and cam do the work. These expensive heads focus on port velocity to get killer flow numbers with smaller ports. Something that makes an NA engine really shine. But it's $$$.
For an all out NA typ app. then yes go with a head that has the last Nth of tricks up its sleeve to 'entice' the air into the engine.
There are plenty of turbo cars with just ported/valved 6L heads putting down >800whp. Save your money.
For an all out NA typ app. then yes go with a head that has the last Nth of tricks up its sleeve to 'entice' the air into the engine.
There are plenty of turbo cars with just ported/valved 6L heads putting down >800whp. Save your money.
In fact power gains will be higher with better heads on an F/I setup than a N/A setup.
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Originally Posted by J-Rod
Good flowing heads don't care if they are N/A or F/I. Boost is a measurement of restriction. A better flowing head will make power at a lower boost level than a restrictive set of heads. Yes, a power adder is a crutch, but it is not a cure to poor flowing heads.
In fact power gains will be higher with better heads on an F/I setup than a N/A setup.
In fact power gains will be higher with better heads on an F/I setup than a N/A setup.
The power adder is a 'crutch' that would've made christopher reeves a sprinter.
An additional 2psi will/would surpass any gains made by trick heads.
If you going MAX effort....buy the expensive heads. But when you break down cost/benefit/other alternatives in an FI situation. It just doesn't make sense.
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
Posts: 4,983
Likes: 13
From: Texas
Case in point. People mistaken believe they don't have to worry about head flow as boost will fix everything. I'll use a Buick GN as an example. You take a motor with a 109 block and the stock iron heads. Lets say as an example the car runs 10.0 at 28lbs of boost. Now you swap it out for a Stage II motor. It'll only take 10 psi to run the same ET.
Originally Posted by J-Rod
Case in point. People mistaken believe they don't have to worry about head flow as boost will fix everything. I'll use a Buick GN as an example. You take a motor with a 109 block and the stock iron heads. Lets say as an example the car runs 10.0 at 28lbs of boost. Now you swap it out for a Stage II motor. It'll only take 10 psi to run the same ET.
I am sure the stock iron heads flow like dog poop too without much runner volume.
NA:
310cfm and a 240cc runner (average for ported stockers) isn't as impressive and doesn't put down the midrange or even peak like an AFR 205 that runs the same flow with a 205cc runner. The ported stocker is cheap, the AFR is expensive. For NA you want port velocity.
Boost:
That same 240cc runner that flows 310cfm would probably do better than the small runner AFR with the same flow. Velocity is moot when boosted, your backing the air up against the valve anyway.
This is why I said go with the darts. They are cheap, they have a few tricks like raised floors, thicker decks, etc..... They are perfect for boost.
I am just trying to help the guy out. It's his money and when the questions are asked "which one should I buy?" Of course, most will say the most expensive....it's not their money. But the cost/benefit value of uber expensive heads go WAY down when boosted. This has been proven over and over.
I'm done here... were going in circles.
Originally Posted by mr2guru
They are perfect for boost.
But seriously, why run two more pounds of boost when you're just increasing IAT's? AFR's and ETP's are both proven heads. I would go with the ETP's if you can find someone with a set in stock. Otherwise go AFR's.
Nate
I have a sweet set of All Pro's that are turbo ready I'm going to sell. They haven't been run. Flow 332 CFM/248 cfm, have 2.08/1.60 Ferrea valves(Super Alloy high temp exhaust valves), Berillium Copper exhaust seats and Cryo'ed Patriot dual golds. Let me know if you are interested. Thanks
Originally Posted by mdhmi
Means nothing. Set your CR via pistons.
Mark
Mark
Nate
Why is it you guys keep saying the Darts have a thicker deck... they have a 1/2" deck (.500").
Also the 62cc chamber is crap for FI. Mark, stick to what you know... IT. If you can avoid it, you never want to use a small chamber head and remove material out of the pistons to regain proper CR with FI. Pistons tend to be the weak link with FI to begin with, why make them weaker? Plus, to get the CR back to where you'd likely want it to be, you might be looking at having to use custom pistons to get you there with the 62cc heads... which cost $$$. And as Nate stated, burn rate is also effected. Stick to 70+cc chambers.
I'd also suggest you go with the larger runners rather than the smaller ones you've listed. This is a big inch FI engine engine so go with 240+cc heads. As stated, port velocity isn't a concern with FI so bigger is better (up to a point).
My 2 cents.
Also the 62cc chamber is crap for FI. Mark, stick to what you know... IT. If you can avoid it, you never want to use a small chamber head and remove material out of the pistons to regain proper CR with FI. Pistons tend to be the weak link with FI to begin with, why make them weaker? Plus, to get the CR back to where you'd likely want it to be, you might be looking at having to use custom pistons to get you there with the 62cc heads... which cost $$$. And as Nate stated, burn rate is also effected. Stick to 70+cc chambers.
I'd also suggest you go with the larger runners rather than the smaller ones you've listed. This is a big inch FI engine engine so go with 240+cc heads. As stated, port velocity isn't a concern with FI so bigger is better (up to a point).
My 2 cents.