+1mm or 44/37 valves

[wowzer]

needing a ported head to support 400+ whp. it will be for my SC with a he351 turbo, fwd f4 cam package, custom ported intake and ported stock exhaust mani. i have a new set of 44/37 valves on the shelf for the '88 782 head currently on the SC. i also have a spare 782 head off a 89 common block. my 2 part question is:

1) should i stay with a +1mm valve or use the big valves, and
2) should i switch to a G head vs the swirl.

this is a daily driver with periodic strip use. lots of threads debating both types of heads/valves which confuses me more than clarifies things. since i have the 782 and big valves that seems like the cheapest way. however, don't want a vehicle i hate to drive on the road unless its doing 5000 rpm! so before i invest money in porting the 782 i want to make sure i start with the best setup. not looking to get to 500whp either (at least for right now!)

[Shadow]

Going to a big valve 782 shouldn't hurt drivability if that's what your asking. The issue with running big valves vs the +1mm's is that most heads are Not ported well enough for those big valves to be any benefit. If you can get the headwork to match the valves you should be fine.

As far as the 782 vs G-head debate; the Charger is still running the +1mm G-head at 550whp and is the fastest spooling HE351 turbo'd 2.2/2.5 that I'm aware of. So tune and supporting mods are what ppl are missing out on when they think the 782 is the better head for drivability.

You say "should I stay with +1mm valves"? What head do you have that already has the +1's? Cause if you already have a +1mm valve head, that sounds like the cheapest way to go, as opposed to building a big valve head properly.

[wowzer]

i currently have a basically stock valved 782 head with just a slight port. i will be getting it professionally ported but want to make sure that using the big valves is not overkill for my desired horsepower level. since i have them on the shelf i wanted to use them if possible. secondly, i want to make sure that using a 782 with big valves is not a waste of money vs a similarly ported G head with big valves.

[5DIGITS]

i currently have a basically stock valved 782 head with just a slight port. i will be getting it professionally ported but want to make sure that using the big valves is not overkill for my desired horsepower level. since i have them on the shelf i wanted to use them if possible. secondly, i want to make sure that using a 782 with big valves is not a waste of money vs a similarly ported G head with big valves.

Recently, I opted for a 'G' head with +1mm valves vs a FB with big valves and over-sized seats because the large seats had already been installed.
The key factor for the choice was over-all flow capability but more importantly the increased squish of the G-head and it's lower tendency to detonate.
To explain, the reason this material was removed from the fastburn was to contribute to swirl charge motion, for emissions purposes.
Where this worked reasonably well for production applications to reduce emissions, it remains one of the largest down-sides when considering a fastburn, for a performance engine.
The key contributor is the 'dead area' on the long side of the intake valve and over-all lack of material on the front side of the chamber.
These characteristics allow the flame front to manifest in that corner rather than being compressed at the center of the chamber near TDC and why the head is so conductive to detonation.
Additionally, this non-centralized burn expansion contributes to uneven energy distribution and why pistons in fastburn applications sometimes suffer skirt fatigue/collapse.

With all this said, fastburn heads are used all the time on performance engines BUT are very receptive to having the chamber welded to avoid spark advance reduction, especially when attempting to use pump gas.
If your going to go through the effort and cost to machine a FB for big seats, weld the chamber prior to having the seats installed, to obtain what the 'G' head has by design.

Thanks

[wowzer]

thx for the info. the cam journals on the head are in tough shape anyhow so instead of trying to save the 782 head by installing cam bearings also i may just hunt for a good G head.

[Shadow]

Recently, I opted for a 'G' head with +1mm valves vs a FB with big valves and over-sized seats because the large seats had already been installed.
The key factor for the choice was over-all flow capability but more importantly the increased squish of the G-head and it's lower tendency to detonate.
To explain, the reason this material was removed when the fastburn was design was to contribute to swirl charge motion for emissions purposes.
Where this worked reasonably well for production applications to reduce emissions, it remains one of the largest down-sides when considering a fastburn, for a performance engine.
The key contributor is the 'dead area' on the long side of the intake valve and over-all lack of material on the front side of the chamber.
These characteristics allow the flame front to manifest in that corner rather than being compressed at the center of the chamber near TDC and why the head is so conductive to detonation.
Additionally, this non-centralized burn expansion contributes to uneven energy distribution and why pistons in fastburn applications sometimes suffer skirt fatigue/collapse.

With all this said, fastburn heads are used all the time on performance engines BUT are very receptive to having the chamber welded to avoid spark advance reduction, especially when attempting to use pump gas.
If your going to go through the effort and cost to machine a FB for big seats, weld the chamber prior to having the seats installed, to obtain what the 'G' head has by design.

Thanks

Nice explaino there bro!

[zin]

Love those "pearls of wisdom"!

Mike

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Love those "pearls of wisdom"!

Mike