World's first FT86 Anti-Reversion,(A/R) Header
 

I had been swapping out intake and exhaust parts for the best low-end torque and best mileage. When I opened up the exhaust with over pipe, mid pipe, and muffler, I would lose about 5 MPG. I could accelerate quicker, but only if I shift down. The low-end torque was not there for traffic acceleration. That is, quickly accelerating 5-10 MPH. That's where the V6's and V8's rule. When I run the stock exhaust the low-end torque is there, but the high-end power suffers. Back-pressure is required for better MPG and torque, but power suffers at high RPM's. After much research I learned that engines DON'T just pump air in a steady stream. They pulse at varying RPM's and varying velocities. If the RPM never varied the perfect manifold would be easy to design, but since it does, therein lies the problem. The best low-end torque is produced by a hot, high-velocity flow, through a narrow, straight pipe. I found a nice 4/2/1 header with accessible center flange bolts,(they didn't cover the center bolt with a primary) and bought 4 Harley A/R cones, then got replacement flanges and had a shop cut off the existing flanges and counter-sink the A/R cones into the new flanges and weld onto the header. See Pics below. I just got installed today and man is it fun! It pulls from 2000 RPM's all the way up to redline. If the power drops off at redline, I couldn't tell. More torque AND more power! The cure for the automatic FT86 is here! :burnrubber:

Do you have any dynos to back this up?

Wow that looks nice

DAT ASS

I'm going to dyno test it in the next few weeks. Have to find a dyno that will test down to 1000 RPM's to show improvement in low-end torque. All the headers I've tried before made it run like a 2-stroke dirt bike, no power down low, but once it's wound up it moved OK. Just OK. Remember I'm driving an A/T so my gearing is way taller than a manual's. I'll post video's once I get them. It's hard to believe this isn't FI the way it drives now. The torque dip is gone completely and it accelerates like it's supercharged. I'll have to find someone else in the Portland/Vancouver area to bear witness to my claims. Who should I ask to test drive it?

Try Wryann at VIP Performance, Portland. He has a dyne shop and a FRS.

I wanna drive this magic torque beast!

PM me your phone number. I'll call and set something up. I'm in Portland all the time.

Interesting. Theoretically you should be able to minimise the reversion with a tune and headers with the right length of runner. It depends a little on why you are lacking torque down low tho. Traditionally if you had a lot of overlap with your cams you could adjust the length of your runners to add some reversion at low RPM to help the air fuel mix in your cylinder and to also scavange from the cyinder at higher RPM. However VVTI makes this fairly redundant.

I am looking forward to seeing the dyno results. A quick google showed mixed opinions in the Harley world. Good on you for giving it a go OP.

Very interested in before/after dyno sheets.

FWIW my AT FRS gained 10-15 ft lbs between 3-7k rpm with just a Borla UEL header, HFC front pipe and a tune. There was no loss of tq or mpg.


IMO you need a tune.

I have been using the OpenFlash tablet for tuning, and even when I had the turbo I noticed the same thing, when I installed larger aftermarket exhaust I lost low-end torque and MPG. I've had catted and catless headers midpipes, flow-through and restrictive mufflers, and the results have always been the same, the less back-pressure there is, the less torque and MPG, regardless of which tune I was running. Maybe this A/R header is finally giving enough restriction for me to run a free-flowing exhaust. I don't know why it works, but it definitely works. I'll try getting some video today.

interesting! keep us posted.

AKA torque cones....These have been around forever..Any Harely rider that's been around a while will recognize them. Here is a dyno http://www.nrhsperformance.com/tech_arcones.shtml

I'm pretty sure there's a good reason why none of the mfg use these "torque cones". Guess some dynos will be able to explain!

If your ever up in bellingham area on the weekends give me a shout, I'll drive down from the border to come drive this, also drive an auto FRS so can help you give some good impressions and would love to find a solid solution to low end torque. I've got the headerback and just installed GS intake which makes the car pull significantly harder from 4000+ need to do something about the low end tho

This is so far from good science it's not worth dissecting. The cure for your automatic acceleration woes is a 4.5FD, not statically reducing the effective diameter of your exhaust ports. You guys are looking for low end torque in a NA high strung 2.0 four cylinder engine. The mind boggles.

Just softened my rear springs by 3/8" to loosen them back up from tightening them by 1/2" to compensate for droop and weight of pc repair parts and tools I always carry in the trunk. Took it for a test drive to my favorite 90 degree corners. Wow, the traction control have never been so annoying! Someone says they have low-end torque, ask them if their TC light keeps flashing every time they gas it in a corner. I would have just turned it off, but I have my snows on and I don't want to wear them out. I didn't have this much TC/AS/SC trouble when I had my turbo. I've got to get this on a dyno!

Seems like a lot of work (and extra exhaust manifold turbulence) for something you can fix with a better header or 4.5FD or 4.88FD or better fuel or driving the car the way it's supposed to be (not in manual mode at < 2000rpm). Skeptical. Good on you for trying something different though.

People who drive the car the way it's supposed to be live on a flat earth and drive a completely stock sports car holding up traffic granny shifting to get better mileage. I've learned to question authority, always, and this car isn't built right. The seats are too hard, the bolsters too tight, sway bars too thick, suspension compression damping too high, wheels too large and heavy, tires too narrow, stereo missing rear midrange/woofers, intake too restrictive, exhaust too restrictive, and I could go on. I love the car, and so I fix what i can, new suspension, new intake, and new exhaust have done wonders. I've got so much more torque now that I can't even touch the throttle in a corner without lighting up the "nanny" dashboard lights, cutting the throttle and buzzing the brakes. How hard do you have to push it before the "nannys" light up?

While I commend your effort in trying something new and look forward to results, I disagree with your above statement. Everything you just said was subjective, I could make counter-points for all the negatives you listed.
Engineers build to the best of their ability while taking into account the parameters they are confined to including safety, emissions, reliability, cost, and scalability. And you can't fault them for that, otherwise we would not be driving these cars today.

bro we are all questioning your butt dyno. either you had the world's worst turbo setup or your mind has truly dissuaded your ability to sense power levels because you're so wrapped up in the idea that these things actually will provide the solution to these FA20s' (designed) lack of torque through the low RPM powerband.

Get it on the dyno then come back to us, until then these videos mean nothing. Looks about as fast as a stock manual imo.

While you may be confident making definitive conclusions based upon your butt-dyno and rudimentary comparative mpg measurements, I shall reserve my judgment pending before and after dyno results.

I do appreciate what you're trying here but think thus far it is too much subjective opinion and not enough science. As for your opinion of the GT86, I agree somewhat. I would rather have a Porsche Cayman S but I couldn't find a new one for $25k.

I'd love to see some dynos as well, I'm willing to bet there are a few things going on here that make me question the validity of this.

First, you've moved to a more efficient catless 4-2-1 header, you would have picked up some power/torque regardless of what diameter your runners are. If I recall, Nameless Performance experimented with smaller diameter runners and did find more low-mid end torque but with a significant drop off up top.

Second, what are you doing tune wise? If you're changing backpressure and flow characteristics without accounting for them properly in your tune you are likely to not be running at optimal performance or efficiency. That doesn't necessarily say it's a better setup, more that it just behaves closer to what the computer is expecting and thus it can run your setup fairly efficiently.

Again, I love to see people experimenting and testing, but if you can get some data around the seat of your pants feeling it would solidify a lot here.


Personally I saw no MPG drop with overpipe/frontpipe/catback nor when I installed my UEL header. Potentially this is more of a problem with automatics based on gearing/shifting differences?

Oh, and when was the last time YOU lit up your TC dashlight?

Everytime I stomp on the accelerator like a moron in 1st gear mid corner.
Sounds like suberman is back again.

nothing a stroker kit wont help with. but its not like everyone going to cross shop a stroker kit with some new header designs...

How much does that header cost?
How much do those AR cones cost?
How much does it cost to get them welded in?

Why didn't you just get a different/better header with dyno proven results? But good on you for doing something different, but i feel its just a waste of money and time if you didn't have any data to back up your subjective feelings.

Let's clarify a few things. I'm driving an automatic BRZ. It's geared much taller than the manual. It takes a lot more umph to break a tire loose in an automatic. My 4th gear is equal to the manual's 6th gear. I have already tried the Unichip piggyback unit, and have been using the OpenFlash tablet for tuning. I have had a completely catless exhaust with dual flow-through mufflers. I have had a turbo, but it wasn't right for a variety of reasons. This is the 3rd after-market header I've tried. I'm using the Unichip CAI for a low-restriction intake right now, but I feel there are better CAI's out there. For whatever reason, an open, unrestricted exhaust has always been disappointing below 3500 RPM's, moving the torque further up the power band, rather than further down, where it needs to be for an automatic, and the mileage has always gone down. I've seen dyno's of AR inserts in Harley's and they show less low-end torque and less top-end power. Experts mentioned they would only recommend them for extremely over-sized exhausts. From what I've read, my header should not perform like I say it does. All I can say is maybe I got lucky. I'll try to line up some test drives with other automatic owners in the area. I don't expect you to believe my lame video or butt-dyno impressions, especially when the "facts" contradict them, but maybe you'll believe other drivers, after they've driven my car. I'm being real here. I don't know all the answers, but if people don't question limitations, how can they get past them?

I should have gone this route instead of blowing my wad on a supercharger. :bonk:

Why not have both, a super exhaust, and a super charger. I'm actually on the list for the Full throttle electric supercharger. You aren't still running the stock exhaust are you? Is yours an auto or a manual? Your supercharged low-end torque would work well with an automatic.

AT 4 and MT 5 are both 1:1, not 6th. You can manually shift down to 1st in AT which you wouldn't manage very well in MT so apart from launches, you have the same number of usable gears. Ratios are different but no it doesn't take any more effort to break traction in AT, you would just be doing it at a different ratio/speed.

I still don't know why you'd want more torque below 2000rpm or even 3500rpm. Shift down or put it in auto mode and press the loud pedal, it takes 0.2 seconds. You're going to give other AT drivers a bad name.

Come back with empirical data if you want anyone to take you halfway seriously.

I don't light that thing up. Either they stay on the street, or I pedal dance/holdtrac in the course or lot.

Can you blame us for wanting some logs/data? Most of us are engineers or scientists in one way or another, if not for the profession

The ratio is the amount of leverage the engine has over the wheels. A stock manual has more wheel horsepower then an automatic because it has more leverage. Dyno tests have proven this over and over. You're telling me to get MY facts straight?

Every time you say something else you come off worse. You obviously haven't seen dynos for AT and MT taken the same day for this car and base all your assumptions on shit from all kinds of older slush boxes. Unsubscribing, no point getting trolled by this joker any more.

Quote because that's funny. A butt dyno is empirical. :D

Empirical - capable of being confirmed, verified, or disproved by observation or experiment.


And while it does say "observation," common usage tends to associate "empirical" with "quantitative" or "verifiable."


A "butt dyno" doesn't provide a useful measurement, you can't quantify it.




Now if he said, his 40-70 times dropped by 0.X amount, that would be useful.

Cherry picking part of the definition that fits your argument doesn't make it the only correct answer.

His empirical evidence is your anecdotal. You can chose to ignore it if you so wish. :D

No engine in the history of 4 stroke internal combustion needs backpressure. The exhaust needs velocity to scavenge all the spent energy from the combustion chamber. There are may ways to do this, but back pressure is not one of them. You are parroting misinformation and a lack of understanding of fluid dynamics.
For an engine to make peak torque at any RPM it must expell as much exhaust as it can at any given RPM. The key to doing this is exhaust gas velocity, not back pressure. Correct diameter pipes that maintain exhaust gas velocity, at the desired RPM and throttle position, are the key to making power.
The reason the back pressure myth continues is bacuse of people putting on too large of an exhaust system which is only effective at a small and high RPM range. At other RPMs and throttle positions too large of an exhaust pipe will cause the exhaust gas to have little to no gas velocity, and can add turbulant exhaust flow which will ultimately cause low RPM drivability issues; it's the reduction in velocity and flow rates that casue problems, not the reduction in back pressure.

"You keep using that word. I do not think it means what you think it means..." 😂

[ame]http://youtu.be/G2y8Sx4B2Sk[/ame]