my perspective on the 'dip'

[ichitaka05]

Originally Posted by Scrappydoo

I have.

If those info wasn't enough, you can take my statement as a false or grain of salt.

[Scrappydoo]

Originally Posted by ichitaka05

If those info wasn't enough, you can take my statement as a false or grain of salt.

That info.

And that's the point I'm making, opinions as stated as fact. The kind of crap that makes a lot of the internet worthless.


Am I going to quietly disappear again? Or are you bigger than that.

[ichitaka05]

Originally Posted by Scrappydoo

That info.

And that's the point I'm making, opinions as stated as fact. The kind of crap that makes a lot of the internet worthless.

Am I going to quietly disappear again? Or are you bigger than that.

Take however you like. It's up to you to research from there. I thought Summerwolf & I were just discussing our knowledge and view instead of proving our statement. If you want me to say, my statement isn't a fact. Okay, it's not and only an opinion. Just my experiences from working on boxer engine (few blow ups lol) and learning from someone knows more than me.

Which reminds me, from his dyno post DOHC EJ tq line was interesting, so I gonna see if it's same for FB engine or FB gonna follow FA engine tq line.

Oh but please don't stop you from proving me wrong. I'm interested to learn if I'm wrong or not. If I'm wrong, cool. If I'm right, cool... either works for me.

[Scrappydoo]

Originally Posted by ichitaka05

Take however you like. It's up to you to research from there. I thought Summerwolf & I were just discussing our knowledge and view instead of proving our statement. If you want me to say, my statement isn't a fact. Okay, it's not and only an opinion. Just my experiences from working on boxer engine (few blow ups lol) and learning from someone knows more than me.

Which reminds me, from his dyno post DOHC EJ tq line was interesting, so I gonna see if it's same for FB engine or FB gonna follow FA engine tq line.

Sorry.

My fault. I didn't realise you didn't know that there were other boxer engines.

i don't want to start fetching facts into this but they've been around as a type of engine for over a century.

None of them as far as I know famous for torque dips.

Exactly the opposite.

But what does everyone else know?

[strat61caster]

Originally Posted by Scrappydoo

i don't want to start fetching facts into this but they've been around as a type of engine for over a century.

None of them as far as I know famous for torque dips.

Exactly the opposite.

Here's 3 pages of VW Beetle dyno charts, not all of them have a dip, some do, a few way worse than the FA20.

http://www.thesamba.com/vw/forum/viewtopic.php?t=362087

Here's a stack of Porsche dyno's from the 80's and a few outliers, most of them don't make within 15% of peak torque below 4k or 4.5k rpm, even at the bottom of the torque dip the 86 is better than that.

http://www.911chips.com/dyno.html


The only reason it's noticeable in the 86 is because the 86 makes incredible torque at ~3k rpm, honestly I almost wish they just detuned it just so I wouldn't have to see three threads a week about it. I mean, it makes as much torque <3.5k rpm as the S2000 puts out peak for crying out loud.

This is not unique to the FA20.

[Lantana frs]

Its easy to pass the fa20 off as "underpowered" til you compare it to other na 4 bangers. Its a very efficient motor that meets some very stringent noise and emission standards.

[Somerandom18]

Originally Posted by Lantana frs

Its easy to pass the fa20 off as "underpowered" til you compare it to other na 4 bangers. Its a very efficient motor that meets some very stringent noise and emission standards.

Right.. NA 4s seems to average 150 at the crank. The fa20 is far from underpowered for what it is.

Sent from my Pixel XL using Tapatalk

[Lantana frs]

These things love the corn. Smoother idle, much more power and I have a station one block away.

[stevesnj]

Originally Posted by churchx

I'm also thinking like that. UEL or Ace header and dip is gone? How it's "engine's characteristic" then?

I saw a video on the use of UEL headers by that engineering guy with the whiteboard and Beatle haircut, it was very interesting. Basically an UEL header isn't a great solution for power increases.

* Edit.. found it, basically if you want the rumble and not significant power gains if any get UEL or EL for power gains though slight it's better than UEL. Subaru uses EL on WRX's now apparently.

[ame="https://www.youtube.com/watch?v=SUiyNud1FX0"]https://www.youtube.com/watch?v=SUiyNud1FX0[/ame]

[Lantana frs]

Slight?

[perryair]

Originally Posted by stevesnj

I saw a video on the use of UEL headers by that engineering guy with the whiteboard and Beatle haircut, it was very interesting. Basically an UEL header isn't a great solution for power increases.

* Edit.. found it, basically if you want the rumble and not significant power gains if any get UEL or EL for power gains though slight it's better than UEL. Subaru uses EL on WRX's now apparently.

i can definitely confirm that the jdl uel that i installed along with tune makes for a much more than a 'seat of the pants' type of increase in power. i dont care enough to spend time and money on a dyno but my driving experience and lots of internet available dynos for uel's that are all readily out there show significant gains through a lot of the usable portion of powerband.

[Hyper4mance2k]

The torque dip has nothing to do with it being a boxer engine. It has nothing to do with it being a flat 4 instead of a flat 6. Correlation does not imply causation.
The torque dip exists due to variations in runner length and port tuning. Boxer engines often have different length exhaust runners between cylinders and thus different torque peaks across cylinders. Subaru does this for easier packaging and lower costs. If all the exhaust ports in the FA20's heads were equal in size, shape, length, and port tuning there would not be a torque dip.
There are plenty of flat engines without torque dips and not coincidentally they have equal length exhaust ports throughout the engine.
Also, Intake port tuning does not need to match exhaust port tuning. Some manufacturers design intake tuning to make peak torque at slightly higher RPM than where the exhaust port tuning makes peak torque for a broader power band, but spread the peaks too far apart in the RPM band and you get peaks.
It is much more complicated than this, but it's a dumbed down explanation. For a real comparison look at power outputs between engines with varying port tuning and you will see torque dips. The VW VR6 is an ensy example of this in an engine that is a cross between an I6 and V6. Really it's a shallow V6 with one head, making it an I6.
I have done all sorts of crazy things building rotaries with varying port tuning to make all sorts of weird power bands. I can make a 13B with a flat torque curve from 3k-8k, and I have also built 13B's with torque dips.
What the madness, a NA 13B with 2 torque dips?!?! This was done by shortening the intake tract, thus moving peak torque tuning for the intake to a higher RPM range(7k goal), and changing the exhaust tuning to make peak torque at 6k.

The same engine. Both intake and exhaust are tuned to make peak torque at 6700 RPM, Before:


Remember, port tuning isn't always going to be perfectly linear up to and down and away from the RPM where peak torque is made, UNLESS the runners are perfectly straight with zero variations (not the real world). With variations in intake runner lengths and shapes you gett all sorts of flow characteristics that favor a few RPM points and even throttle positions. You can actually design an engine that makes more part throttle torque at say 3k rpm than it would at 3k and wide open throttle due to port flow, velocity, etc.

[Hyper4mance2k]

Also, there is no real UEL vs. EL header debate because you don't honestly know which headers are EL. Are they EL in just runner length, or in volume length, or if they're just equal from the back of the valves with no consideration for variations in port volume.
Hell your UEL headers might work so well because they're actually EQUAL length in exhaust port volume, though probably not. Maybe just by happenstance they are equal for both banks, and that's why they work. You simply cannot make a scientific argument based on anecdotal evidence.
If you want to know why the ACE header works so well, they claim it is equal length in port volume and length from the back of the valves to the collectors. I can't confirm this, but if that's true, if you actually measure the runners they will not be "equal length."
One of these days I would like spend the time designing a 4-1 equal length header, equal in exhaust pulse length tuning at a specified RPM, with a true scavenging collector. However packaging something like that in this chassis would be horrendous.
You can actually do it without math. The easiest way to do it would be to run the engine with perfectly straight runners attached to each exhaust port, with a load, at the RPM you want to make peak torque and the hottest point on the each runner would be where you would have them collect into a scavenging collector. Of course runner size and a million other things come into account, but it can be done.
If you have a chrome header, install it, and run it on a dyno. Then take a look at it and note where the purple hot spots are. If they're not on bends, and other obvious flow restrictions, than your header isn't properly designed to maximize peak torque, across cylinders, at a specified RPM. Ideally, the runners should only discolor right at the collector and at the collector.

[Scrappydoo]

I only know that skinny dipping is good and double dipping bad