I wonder why the P-Tuning 4-1 doesnt do so well in the mid-range torque dip area. They even considered the firing order designing the pipes. It's the most well made header for this car on the market, I think, in terms of craftsmanship. Performance seems to fall a little short.

Absolutely. The car's behavior has changed massively and the 4-1 header really rewards winding the motor to redline. Some may want more torque down low but I love the high-revving nature of the FA20 so the 4-1 EL is perfect for my driving style.

nearly 160 ft lbs of torque from 3600rpm up is a lot of torque, relative to stock. Relative to most aftermarket setups, for that matter.

It's a beautiful torque curve. A very peppy one.

w

Unless you have a 4-2-1 long tube header. Best of both worlds.

el 4-1 still give more peak power and in generally they make the car come alive brutally after you pass 5.5k rpm

I'm still under impression that even on track midrange & total area under curve is more important for actual goal, to accelerate/drive faster, then higher peak number. Not just peak hp for very very narrow rpm range powerband you spend second in before upshifting. Hence good longtube 4-2-1 headers like that of Ace/JDL/Nameless seem preferable choice to 4-1 .. that actually also can be as effective theoretically, if they had similar long runners to optimize scavenging at mid-rpms, but in reality are not, due packaging reasons. It was hard to get long runners in 4-2-1 design like for Ace/Nameless .. now imagine to try to get 4 tubes as long as in those 4-2-1 .. pack not just 2 but 4 tubes before engine or where overpipe goes. Hence due limited clearance 4-1 is destined to be with short tubes, which means - optimized for very highest rpm range only, and imho that is relatively rare/specific usage case (eg. built NA engine with fixed oiling limitations and running with much higher redline) where it might be beneficial over midrange or overall gains across. Even on track. Even though it's not fault of 4-1 design itself, but simply that there is no space for long enough tubes of doubled count.
Of course in hypothetical ideal world we would have as much space under bonnet as more then half a century ago to alleviate clearance/design limitations and variable adjustable (or multipath selectable) intake and exhaust tube lengths for always to be at most optimal length (IIRC like it was done in some supercars). But otherwise it's not 4-2-1 vs 4-1, but "longtube 4-2-1" vs "short tube 4-1".

JDL 4-2-1 isn’t a long tube header.

Nameless still has short 4-2 runners, it has long 2-1 runners before the merge for great mid range. But needs longer 4-2 runners for top end.

ACE has long 4-2 runners, the 4-2 runner length before the merge is as long or longer than the 4-1 EL runners. Allowing for good top end and then has the scavenging and efficiency of the 2-1 step down for mid range giving you best of both worlds. The later can be adjusted by the OP design 150/250/350 allowing more mid range or more top end by adjusting those lengths. But even the 350 has good top end because of the 4-2 length and the 150 has decent mid range because of the 4-2-1 design. In my personal opinion the ace 250 is the perfect no compromise header.

Believe it or not some people still think its all marketing the torque dip isnt a thing.

Same dyno but different correction factors and loads on all printouts. If dynos aren't under the same test setup you can't compare a thing..

E85 JDL UEL


https://i.imgur.com/8otRCTe.jpg

Hmm... I wouldn't say the performance falls short, just heavily skewed towards the top-end where it is still arguably the best performing header on the market. PTuning stated one of their design goals was to minimize sweep in front of the engine to keep engine bay temps down, so they were probably limited on space for runner length (and possibly midrange power).

Yeah it sounds like you picked the right header for your driving style. Glad you're happy with it setup - it looks like it'd be a lot of fun in everyday driving.

I'm not a dyno expert, but OP's dyno run looked like it was using a standard 1.00 correction factor. I didn't see a correction factor listed on the @PandaBRZ dyno chart. Do you have some reason to believe it was using a large CF?

Not larger just, different. The same dyno with SAE vs STD correction factor will give a different output. Also having a load off or on effects it as well.

Another thing about mid range vs top end. Mid range torque cost less fuel than top end power. Maybe? How would we test this? Hmm...

solidONE: imho fuel economy is not worth splitting hairs about. Technically similar energy should be spent to get upto speed, be it done slower with granny shifting (but for longer period), or faster (but for shorter period and then driving longer with more efficient higher gear). Of course less pumping and drivetrain frictional losses at higher gears at lesser engine rpms may save a bit .. but also will reduce acceleration rate/wheel torque due gearing. Simpler to just not think of fuel economy and have fun driving instead of sedate ecomiling. People pay for comfort, why not pay slight premium for fun. Same reason why i fill with 98 petrol even while manual states that cheaper 95 is ok, and why often from traffic lights shift 1-2-5 or 1-2-6 :).