I suppose the torque wasnt relevant since most small displacement NA motors are fairly anemic that way. Not sure if that is due to longer stroke being less efficient or emissions.

You cannot compare voluemetric efficiency on a rotary displacement since it works completely different. Suffice it to say I'll take reciprocating over rotary any time

now that i mostly agree with. i just dont understand why you say you cant compare volumetric efficiency. why is that the only thing you dont want to compare? nobody has any issues comparing the mileage or maintenance but when it comes to its most significant upside, all of a sudden we cant compare it.

Im no expert but I think earlier in the thread someone said the rotary displacement is equal to 2 x so 1.3 L is actually equal to 2.6 L, so its less efficient. Maybe since it isnt 4 stroke.

thats pretty much what they mean. i think its because a 4 stroke piston engine has to turn the crank 720* while a rotory only uses 360*. the thing is, that doesnt make it less effecient. it just means its not twice as efficient. we can make equivocations but at the end of the day, the 13b is still only 1.3l.

that being said, i still dont think its one of the greats. i just get a little frustrated by these "all things equal" kind of points. in my opinion, "all else equal" means "if you take away all of its advantages and leave only this specific disadvantage i am bringing up, it is at a disadvantage." im not saying thats your intention but i feel thats kind of what is happening

my thoughts are that if the rotary engine was so great why didn't other manufacturers license it is well. to me it's more of a novelty item something Mazda needed to differentiate itself as a relatively small fish in a big sea.

In 89/90 I sold Mazda. The RX7 wasnt selling so well and at the time it ocurred to me that the 240SX had a better engine and was a better overall value.

the boxer isnt exactly ubiquitous either. the rotary is simply millions of hours behind piston engines in technology and it suffers from that.

Anyone who has worked with the K20A motor knows that there is something next to godly in the way that motor was built. It is literally a race motor tamed for the street via the VTEC mechanism which the FA20 unfortunately lacks. Case in point, if the FA20 had cams as big as the K20A it would not be able to idle.

Also in response to Honda not building ultra high power NA motors anymore, that is directly related to the move in the motorsport world to a unified 1.6L turbo engine.

The KA20A has a forged crank vs the cast cranked FA20. I thought that the K20 also had piston oil squirters? FA20 just wasn't built for variable lift or high revs like a K series or the F20C. Time will tell if the FA20's open deck can really handle boost without head gasket issues.

My vote goes to the F20C for NA and the SR20DET for FI. Bullet proof reliable engines that have stood the test of time.

I've personally never been a fan of cars with variable lift. That jekyll and hyde low-RPM/high-RPM behavior was always a turn off for me.

Making the same amount of power over a linear curve of powerband is preferable to the erratic behavior of an engine with variable lift. 2ZZ-GE is also similar in that regard. I feel as if the high-RPM power is too big a trade off for the horrendous low-end power. Luckily, the other famous DOHC VTEC engine (NSX's C32B) doesn't exhibit that on/off behavior of the B and K series engines.

You like 6 cylinders. Very rare for a 2L 4 cylinder to have a linear powerband, maybe the old BMW S14.

The 3S-GE BEAMS and SR20VE both have fairly linear powerbands. The power delivery of both engines are more similar to that of the FA20. That doesn't mean I don't think the Honda engines aren't fantastic, they make great power, it's just not my ideal power output. However, given the choice between the FA20/3S-GE/SR20VE like delivery and the erratic variable lift engines with an additional dallop of power, I still think it's silly not take the F20C or K20A which have between 10-30HP more than the previously mentioned engines. Then again... emissions and efficiency need to be assessed, too? Aye, it's a hard choice. But given our current day choices in a new car, it's a FA20 or... something turbo charged, right?

What you need were Toda Vtec killer cams. It basically swaps the Vtec lobe so it's on all the time. There are also guys who would take the K24A1 out of a CRV (which you can get for super cheap..300-400 usually) and add the K20A2 valvetrain and put down solid numbers. An average dyno would be 200/180 and along with some elbow grease you could pay about $800 for that motor.

Also, I'd say the K and B series engines were much different in their power delivery. Yes there was a noticeable gain even in the Ks but it was a much smoother progression than the sharp break of the B series. So much that many people didn't like the K series when they came out because they were too smooth.

They don't all have a dramatic change from low to high RPM. Check out the engine in the Porsche Cayman, which has VVT and 2-stage lift on the intake side. Look how flat the torque curve is (within 15 lb-ft of peak from 2300rpm onwards! From a N/A engine!)- there's no jekyll and hyde behavior here:

http://caymanregister.org/images/FAQ...rque_curve.jpg

Wow the shape of that torque curve looks very reminiscent of the FA20, just scaled higher.

- Torque peak at 2500 rpm
- Torque dip from 3200-4500 rpm
- Flat torque from 4500-6500 rpm
- Power drops off at 6500 rpm
- 7400 rpm redline

http://media.ed.edmunds-media.com/sc...011123_600.jpg

im pretty sure the reason vtec exists is to negate what you are blaming it for causing.

Yep - I've always found it pretty neat how qualitatively similar the Cayman and BRZ torque curves are - they really do look like nearly the same engine rescaled. The Cayman S has pretty much the same shape as well (but scaled even higher). The torque dip around 3.5k is noticeable, though not too bad on the CS. Note that both the Cayman curve I posted above and this CS curve are from the old (pre-2009) engine, but the new one also looks pretty similar, just with a bit of extra power.

http://caymanregister.org/images/FAQ...rque_curve.jpg


As a point of comparison, here's the new one:

http://www.autozine.org/0_News/Archi...an_S_power.jpg

It's not an issue when you're driving on a track. Unless there are some very low speed turns if driven properly the engine will never come off the larger high lift cam. As an aside, it's also worth noting that Honda's VTEC system is bulletproof. There has never been a warranty claim made on the system, ever. And after 300k miles I can say that I haven't had a single issue with VTEC on my Integra. Truly amazing.

I wonder what the difference is in newer cars (say like our FA20) single cam profile versus a VTEC 2-stage lift cam profile on a K or F series engine. The reason for the 2-stage lift is to improve idle as the primary function but also to provide improved responsiveness at low-RPM, but for some reason, didn't most of those engines have lesser torque at a given RPM than their less performance oriented counterparts (ie. 1ZZ vs. 2ZZ; B18A vs. B18B, etc)?

The F20/F22 have less torque in the low-RPM range than the FA20 does at similar RPM.

Yeah, Honda does have super reliable engines. I've always been blown away by that.

That's really interesting. I wonder if being a 6-cylinder engine helps negate that jekyll and hyde power delivery? Or maybe the cam profile switch is just so much more gradual (the low-high profile is much less aggressive than on the K and F series engines).

Interesting, thanks for posting. I've seen a couple of NA engines now that have this kind of torque curve with a dip in the middle. I wonder if they are a byproduct of manufacturers pushing for more low-end grunt at the expense of the midrange.

Can you eliminate the torque dip on the Caymans with a header/tune?

Maybe? I don't know - I honestly haven't felt a need to on mine. It's making 222 lb-ft at the lowest point on the dip, so even though it's noticeable, it definitely doesn't feel anemic anywhere in the rev range. For performance-oriented driving, I just keep it above 4300, and for non-performance oriented driving, the dip isn't severe enough for me to have any real complaints, so I haven't looked into it. It would be interesting to find out though.

well a pretty big difference besides being a decade newer would be the addition of direct injection. if the 2 stage lift was for the benefit of idling, why would they keep that first cam active up into the 5k range? the primary reason for that was to keep the low end tq without impairing the motors ability to scream up top.

I would tend to guess that it's a much more gradual switch. Looking at the torque curve on a Vtec engine, I almost wonder if Honda intentionally tunes it to be an abrupt shift so people can feel vtec kicking in.

Yeah good point, with more torque to begin with, it's probably less of an issue. The driving style on the FR-S is similar, have to keep the revs above 4500 rpm for performance.

Yep agree, DI (and consequently, the high compression ratio you can run with DI) would be the reason the FA20 produces relatively good low-end torque vs. the older Hondas from what I understand.

Honda stated they used to tune engines that way for marketing, to let people know what VTEC was doing. Recent Honda engines have a seamless transition though.

GM Quad-4 W41
Subaru EJ20R (Its in in a JDM Legacy model, put out over 190hp without DI)

EJ20R

Usage:

• 1996-1998 Legacy chassis code BD/BG5 [ame="http://en.wikipedia.org/wiki/Japan_Domestic_Market"]Japanese domestic market - Wikipedia, the free encyclopedia[/ame] manual RS-B and GT-Bs (206 kW (280 PS; 276 bhp) Manual)

Yes this was a performance engine, in direct contrast to the FA20. The EJ20 series was developed in the 80's and the whole series was built to last and perform, the R even had forged pistons. Oh high far we have declined.

The dip is nothing new at all. My ancient 3.1 liter SOHC Datsun engine with a big cam had this exact feature. It is an artifact of tuning for higher-rpm performance, you end up "anti-tuned" and get very low volumetric efficiency at some lower rpm range. It's an inherent feature of most NA engines.
http://www.classiczcars.com/photopos...4sep02run7.jpg
It later did 255rwhp :) I miss that car :(

Yeah I could understand the dip in cars that are limited to a single cam profile (and esp those without VVT), but it's interesting that the Caymans have the same dip. Don't they have variable lift and timing? You would think they could tune that dip out.

The problem with the FA20 dip is it drops to 100ft-lbs at the wheels, that is just not enough for a 2800 lbs car.

Your car has no transmission?

No, thats not the EJ20R I was referring to... There is actually a Legacy model named the EJ20-R

http://www.google.com/url?sa=t&rct=j...,d.cGE&cad=rja

I do but remember the OEM has claimed driving near redline is considered abusive for this engine, this is coming from corp. technical sevice reps according to posts on this forum.

This was reported just last week


The whole Ej20 series was based on solid engineering, led to the ground breaking first gen WRX.

You missed the point - even in the torque dip, you're making a LOT more than 100 ft-lbs at the wheels because of the transmission. Specifically:

1st gear: 1480 ft-lbs at the wheel in the torque dip (for 6MT)
2nd: 897 ft-lbs
3rd: 632 ft-lbs
4th: 497 ft-lbs
5th: 410 ft-lbs
6th: 314 ft-lbs

(all assuming no loss, 100ft-lbs at crank).

Yes but that's relative. Those numbers are very low for a sporty 2800lb car. If it had 18 gears maybe your point makes sense to me :lol:

It is relative, if your complaining about it you're the one who bought the wrong car. Complaining about the torque dip is as stupid as about complaining about a turbo engine boost lag, or the lack of top end power of a diesel.

People often complain about the dip but rarely praise having two power bands.

How is pointing out a fact complaining? This a list of the best 2L N/a engines of all time. In stock form the FA20 just doesn't belong on the list IMHO. Many people including professional auto reviewers point out the torque dip and the FA20 never gets raves reviews by any auto reviewers. The existence of a dip isn't the issue, its the severity of it right as you rev over 3k.

BTW the torque dip is easily eliminated with proper tuning and headers, no reason to label stupid the majority who rightly believe 100ft-lbs at the wheels (in the dip) is not enough for a 2800lb car. Smart is CI and that is typically started by identifying areas of deficiency.

I mentioned this before.. I test drove the car before I bought it. To tell you the truth.. The tq dip is not really an issue in everyday driving.. Most of these people complaining about it wouldn't even know it existed if it wasn't for the dyno printouts. It looks worse on paper than it actually feels in the real world.
If it was as bad as some mention.. Why did they buy the car in the first place?
You can always maintain rpms to where you land above or below the "dip" if necessary. The OEM did a good job of keeping tq low and high in the powerband considering the engine size, rpm range and budget they had to work with.
The overall package works great! The compromises made are reasonable and still deliver a great driving experience.. Especially considering the cost of entry.
I wouldn't want to lose my warranty over a tune trying to fix something that's not really an issue to begin with..

What fact? C&D, motortrend and every other review by a professional reviewer I have seen has never mentioned the tq dip or driveability issues.
Not everyone wants to void their warranty with a tune.. Or thinks there is a need for a tune, headers.
It's not the engine that makes this car so special.. It's the right combination of parts.. While the engine is no huge stand out.. It's 100hp per L and fuel economy are respectable and match the chassis well.. Not to mention the awesome throttle response and CR.. Not much to complain about IMO.

That Alfa Romeo 16v 2.0 in the old 164

And every recent review I've read wants more engine output with the twins, even Pobst's latest comments are "add a turbo", and this thread is about the best 2L NA engine's ever. The FA20 just isn't there. As you say it isn't a huge stand out.