Comparison of the best ~2 liter N/A engines ever produced

[DarkSunrise]

Originally Posted by chrisl

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.

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

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?

[chrisl]

Originally Posted by DarkSunrise

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.

[fatoni]

Originally Posted by ThisIsChrisKim

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.

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.

[chrisl]

Originally Posted by ThisIsChrisKim

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).

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.

[DarkSunrise]

Originally Posted by chrisl

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.

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.

Originally Posted by fatoni

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.

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.

Originally Posted by chrisl

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.

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.

[Kostamojen]

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

[regal]

Originally Posted by Kostamojen

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.

[ZDan]

Originally Posted by DarkSunrise

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.

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.

It later did 255rwhp I miss that car

[DarkSunrise]

Originally Posted by ZDan

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.

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.

[regal]

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.

[Rayme]

Originally Posted by regal

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?

[Kostamojen]

Originally Posted by regal

EJ20R

Usage:

• 1996-1998 Legacy chassis code BD/BG5 Japanese domestic market - Wikipedia, the free encyclopedia 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.

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

[regal]

Originally Posted by Rayme

Your car has no transmission?

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

Originally Posted by DoomsdayJesus
I forgot to mention, one of the gems the service rep told me the techline related, is that "the car's not meant to be driven that way," i.e. shifted around 7k RPM. .

Originally Posted by Kostamojen

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

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

[chrisl]

Originally Posted by regal

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.

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).