Trick flow heads & cams with NPI bottom end - TCCoA Forums
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post #1 of 5 (permalink) Old 03-08-2019, 05:47 AM Thread Starter
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Trick flow heads & cams with NPI bottom end

Im curious how the NPI pistons would hold up with the bigger cams and if the valve clearence would be an issue

What kind of gains would I be looking at?
Already did a PI swap but lets face it those heads seem really nice LOL
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post #2 of 5 (permalink) Old 03-08-2019, 10:49 AM
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Valve clearance and strength is no different than with a PI piston, the dish doesn’t allow for more valve clearance.

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post #3 of 5 (permalink) Old 03-08-2019, 11:09 AM
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That all completely relies on how much you're willing to spend, and how big you're willing to go...

The Trick Flow twisted heads ARE really nice, but they are high-performance heads meant for people with deep pockets and big ambitions....

For example, even with the smallest TFS cams on the TFS heads, the engine won't really wake up until around 4k and will live from there to 6k, the ports flow a lot more where it counts. Get the big cams, and you'll need to wind it out past 7 to make any real use of the heads. Bottom-end torque unfortunately falls flat with these heads/cams, but you get it all back in the upper range. You can get them in 44cc chambers or 38cc chambers. Intake valves are I think 1.85" compared to stock 1.74".

The heads themselves relocate the intake valves, so non-TFS cams will not work with TFS heads. This relocation helps the engine breathe, improves swirl, and (they claim) greatly reduces PTV issues... though you will need TFS pistons for anything bigger than "Stage 1" (ironic considering the same can be said for any other brand).

The exhaust ports are D-ports as opposed to the O-ports on the stock heads, and the heads themselves are designed similar to Windsor castings (they accept both valve covers and most timing covers). The cam journals are individual cap (Romeo are girdled) and are not only better at holding and oiling the cam, but are entirely replaceable should a cam wipe out... no line-bore required.

You can expect a TFS setup with "Stage 1" cams to outperform a PI setup by at least 20hp in stock trim, that gap getting exponentially bigger as you mod the hell out of the thing.

They are completely worth the money -- if not for the performance aspect then for the peace of mind from the improved oil pressure, deeper spark plug threads, greater cam stability, and ability to replace cam bearings (caps and towers) -- but keep in mind they are a performance head and meant for high-revving builds.
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post #4 of 5 (permalink) Old 03-08-2019, 03:23 PM Thread Starter
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Well, in the grand scheme of things I want to turbo it.
Ideally keeping the stock block, and eventually replacing internals with a studly & tuff sort of rotating assembly. No particular brand in mind at the moment, but the internals wouldnt handle a turbo with the miles on the engine. Also the peace of mind would there LOL
Currently dressing up the exterior & suspension, then it will be back to the motor and tranny..

That 4r70w needs some love and a proper valve body rework if shes gonna handle the HP 🤔
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post #5 of 5 (permalink) Old 03-08-2019, 03:31 PM
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If you're gonna boost it, then TFS heads are the way to go for sure. Lots of folks swear by Manley parts for the guts, but there are lots of good brands out there to choose from.

I'm actually about to tear apart my 4R70 soon as I slap my gas tank back in, so probably this weekend if I'm lucky. Will be doing rebuild with valve body mods and Stage 1 Ray clutches with kolene steels, also Fairbanks pistons, and lots of other stuff. Nothing too serious, it's just a warmed-over NA PI build.

I would recommend getting the Sonnax zip kit and forward drum, fix all the weak spots.
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