[Keanu443]

I have a 2010 LXS w/ no VTEC and I've been reading all around the forums and internet about which engine I should have in my car. I've gotten different answers all around. So from what I understand the K24Z2 is the lower of the two which I assume would be mine and the VTEC i4's are the K24Z3's?

 

[outersquare]

The coupes all have 190HP K24Z3

 

[Keanu443]

K24Z3 VTEC and Non-VTEC

Is there a difference in hp for this generation between the two or does it all come down to tuning?

 

[Hudouc]

Is there a difference in hp for this generation between the two or does it all come down to tuning?

K24Z3 190hp/162 lb⋅ft Redline @ 7100RPM Compression at 10.7:1
K24Z2 177hp/165 lb⋅ft Redline @ 6800RPM Compression at 10.5:1

If I remember correctly, the Z2 and Z3 have slightly different internals (thus the difference in Redline)

The K24Z3 also had different tunes, the K24Z3 in the TSX is rated at 201hp/172 lb⋅ft with Redline @ 7100RPM and Compression at 11.0:1

 

[Keanu443]

Right, so as the previous person stated, the coupes all are the Z3's but then it branch's into VTEC variant's and Non-VTEC variants? So is there a difference in HP when that's applied?

 

[Hudouc]

Right, so as the previous person stated, the coupes all are the Z3's but then it branch's into VTEC variant's and Non-VTEC variants? So is there a difference in HP when that's applied?

I believe all K24Z3 came with i-VTEC. I don't think any K24Z3 came without i-VTEC.

 

[Keanu443]

Right so that brings me to same info i keep finding all over. If all coupes are Z3's and i have an LX-S which has no VTEC then is it a Z2?

 

[Hudouc]

Right so that brings me to same info i keep finding all over. If all coupes are Z3's and i have an LX-S which has no VTEC then is it a Z2?

Sorry for the misunderstanding. Your coupe (in LX-S trim) has a K24Z3 Engine equipped with i-VTEC. Making exactly 190hp/162 lb⋅ft.

 

[outersquare]

You can find all these answers with search but because I am nice I typed out a reply;

All the K24Z accords have the same compression ratio, it is 10.5:1. Last I looked, the K24Z2 and K24Z3 had all the same major engine internals, pistons, rods, crank, cams. The valve springs and bearings had different part numbers but that doesn't say what the difference actually is. Parts lists can be found on estore.honda.com

Consequently, all K24Z accords have full VTEC but only on the intake side. None of the K24Z accord/TSX/civic SI have full VTEC on the exhaust side, all of these engines have only one cam lobe. The PZEV/CA model K24Z accord does have some sort of VTEC-E on exhaust, but it only runs 1 valve at low rpm does nothing else.

The K24Z2 only came in LX, LX-P and SE sedans. As far as I ever saw, the power difference is just tuning, Honda artificially capped the K24Z2 engine with a lower redline and a smaller exhaust. During Ktuner development, Ktuner and one of our members/testers basically recovered all the power with the raised redline and bigger exhaust.

http://owners.honda.com/vehicles/information/2012/Accord-Coupe/specs#mid^CS1B3CEW

08-12 Accord i4 ? KTuner, LLC

 

[Keanu443]

Okay, so correct me if i'm wrong, when it comes down to the Z3 saying VTEC across the engine and not across the engine, all it means is how many valves will run at certain RPM's?

 

[BanzaiRocket]

Okay, so correct me if i'm wrong, when it comes down to the Z3 saying VTEC across the engine and not across the engine, all it means is how many valves will run at certain RPM's?

Let's make it simple. There's no such thing as a "Non VTEC" 8th gen Accord. All 8th gen Accords have VTEC.

The V6 has 2 different versions: the "VCM" iVTEC found in the automatic transmission equipped V6's. And the non VCM regular VTEC (not iVTEC) V6 found in the manual transmission equipped V6's.

The 4 cylinder has 3 variations (2 of which are slight variances of the Z3): The K24Z2, and the K24Z3. The Z2 is found in the Accord sedans, in the model trims: LX, LX-P, and SE (SE is a Canada only car). The Z2 was more restricted in terms of it's ECU tuning, and the exhaust being smaller diameter than the systems on the Z3 models, as well as the muffler being more restrictive. The K24Z2 is an iVTEC engine.

All of the 4 cylinder 8th gen Accord coupes (yes, all trim levels: LX-S, EX, & EX-L, both manual and automatic transmissioned) all came equipped with the Accord tuned version of the Z3, which are all iVTEC engines. The Z3 version has a larger diameter exhaust system than the Z2, and a higher flowing muffler, and more performance oriented ECU tuning.

The other variable of performance between the Z2 & the Z3 is the transmission and the PCM tuning. The Z2 is geared a little differently, and the PCM tuning is not intended for performance, but rather for economy and efficiency.

The automatic transmission in the Z3 equipped cars is more performance oriented in the PCM tuning, and has "sportier" gear ratios.

Now, for the "3rd version" of the K24Z, being the 2nd version of the K24Z3, which is the Acura TSX version, not the Accord version. It has slightly higher compression than the Accord, different ECU tuning, and electric power steering instead of a traditional power steering pump. Further, the TSX with automatic transmission has a magnesium transmission case which is approximately 9-10 pounds lighter weight than the Accord transmission case. The TSX also comes with a performance tuned PCM and oriented transmission, and is a little more refined than the Accord's transmission.

Furthermore than that, the 2nd gen TSX ('09-'14) has the option of paddle shifters for it's version of the K24Z3 with 5 speed automatic transmission.

The other variation on the 2nd gen TSX with K24Z3 is that they had the option of a 6 speed magnesium cased manual transmission with close gear ratios.

There are other variations of the K24Z series, but not in the Accord or "Accord related platform being the TSX".

As stated by someone else, the K24Z2 & Z3 in the Accord utilizes iVTEC only on the intake cam, not on the exhaust cam. The only thing the exhaust cam has "special" is the "VTEC-E" feature as mentioned, in which what it does is only activates 1 exhaust valve per cylinder below 2,500 rpm, once the engine reaches 2,500 + rpm, a mechanism is activated which operates both exhaust valves.

The purpose of the "1 exhaust valve" per cylinder in low rpm is optimization of fuel efficiency and low rpm torque delivery. It's actually not a bad thing, it helps reduce emissions, more effectively uses fuel, generates more power and torque in the low rpms, and is helpful in performance applications by optimizing swirl and quench for more effective ignition which helps reduce knock, ping and predetonation. But that's a totally different conversation.

 

[GreenMM]

I have an '11 LX-S Coupe. As stated they are all 190 HP engines with the i4. They don't come in the lesser HP version.

 

[rigostar1931]

Okay, so correct me if i'm wrong, when it comes down to the Z3 saying VTEC across the engine and not across the engine, all it means is how many valves will run at certain RPM's?

Let's make it simple. There's no such thing as a "Non VTEC" 8th gen Accord. All 8th gen Accords have VTEC.

The V6 has 2 different versions: the "VCM" iVTEC found in the automatic transmission equipped V6's. And the non VCM regular VTEC (not iVTEC) V6 found in the manual transmission equipped V6's.

The 4 cylinder has 3 variations (2 of which are slight variances of the Z3): The K24Z2, and the K24Z3. The Z2 is found in the Accord sedans, in the model trims: LX, LX-P, and SE (SE is a Canada only car). The Z2 was more restricted in terms of it's ECU tuning, and the exhaust being smaller diameter than the systems on the Z3 models, as well as the muffler being more restrictive. The K24Z2 is an iVTEC engine.

All of the 4 cylinder 8th gen Accord coupes (yes, all trim levels: LX-S, EX, & EX-L, both manual and automatic transmissioned) all came equipped with the Accord tuned version of the Z3, which are all iVTEC engines. The Z3 version has a larger diameter exhaust system than the Z2, and a higher flowing muffler, and more performance oriented ECU tuning.

The other variable of performance between the Z2 & the Z3 is the transmission and the PCM tuning. The Z2 is geared a little differently, and the PCM tuning is not intended for performance, but rather for economy and efficiency.

The automatic transmission in the Z3 equipped cars is more performance oriented in the PCM tuning, and has "sportier" gear ratios.

Now, for the "3rd version" of the K24Z, being the 2nd version of the K24Z3, which is the Acura TSX version, not the Accord version. It has slightly higher compression than the Accord, different ECU tuning, and electric power steering instead of a traditional power steering pump. Further, the TSX with automatic transmission has a magnesium transmission case which is approximately 9-10 pounds lighter weight than the Accord transmission case. The TSX also comes with a performance tuned PCM and oriented transmission, and is a little more refined than the Accord's transmission.

Furthermore than that, the 2nd gen TSX ('09-'14) has the option of paddle shifters for it's version of the K24Z3 with 5 speed automatic transmission.

The other variation on the 2nd gen TSX with K24Z3 is that they had the option of a 6 speed magnesium cased manual transmission with close gear ratios.

There are other variations of the K24Z series, but not in the Accord or "Accord related platform being the TSX".

As stated by someone else, the K24Z2 & Z3 in the Accord utilizes iVTEC only on the intake cam, not on the exhaust cam. The only thing the exhaust cam has "special" is the "VTEC-E" feature as mentioned, in which what it does is only activates 1 exhaust valve per cylinder below 2,500 rpm, once the engine reaches 2,500 + rpm, a mechanism is activated which operates both exhaust valves.

The purpose of the "1 exhaust valve" per cylinder in low rpm is optimization of fuel efficiency and low rpm torque delivery. It's actually not a bad thing, it helps reduce emissions, more effectively uses fuel, generates more power and torque in the low rpms, and is helpful in performance applications by optimizing swirl and quench for more effective ignition which helps reduce knock, ping and predetonation. But that's a totally different conversation.

Awesome post! I understand my 2010 EX engine better now. Thank you for writing this up.

 

[Jsern9]

Let's make it simple. There's no such thing as a "Non VTEC" 8th gen Accord. All 8th gen Accords have VTEC.

The V6 has 2 different versions: the "VCM" iVTEC found in the automatic transmission equipped V6's. And the non VCM regular VTEC (not iVTEC) V6 found in the manual transmission equipped V6's.

The 4 cylinder has 3 variations (2 of which are slight variances of the Z3): The K24Z2, and the K24Z3. The Z2 is found in the Accord sedans, in the model trims: LX, LX-P, and SE (SE is a Canada only car). The Z2 was more restricted in terms of it's ECU tuning, and the exhaust being smaller diameter than the systems on the Z3 models, as well as the muffler being more restrictive. The K24Z2 is an iVTEC engine.

All of the 4 cylinder 8th gen Accord coupes (yes, all trim levels: LX-S, EX, & EX-L, both manual and automatic transmissioned) all came equipped with the Accord tuned version of the Z3, which are all iVTEC engines. The Z3 version has a larger diameter exhaust system than the Z2, and a higher flowing muffler, and more performance oriented ECU tuning.

The other variable of performance between the Z2 & the Z3 is the transmission and the PCM tuning. The Z2 is geared a little differently, and the PCM tuning is not intended for performance, but rather for economy and efficiency.

The automatic transmission in the Z3 equipped cars is more performance oriented in the PCM tuning, and has "sportier" gear ratios.

Now, for the "3rd version" of the K24Z, being the 2nd version of the K24Z3, which is the Acura TSX version, not the Accord version. It has slightly higher compression than the Accord, different ECU tuning, and electric power steering instead of a traditional power steering pump. Further, the TSX with automatic transmission has a magnesium transmission case which is approximately 9-10 pounds lighter weight than the Accord transmission case. The TSX also comes with a performance tuned PCM and oriented transmission, and is a little more refined than the Accord's transmission.

Furthermore than that, the 2nd gen TSX ('09-'14) has the option of paddle shifters for it's version of the K24Z3 with 5 speed automatic transmission.

The other variation on the 2nd gen TSX with K24Z3 is that they had the option of a 6 speed magnesium cased manual transmission with close gear ratios.

There are other variations of the K24Z series, but not in the Accord or "Accord related platform being the TSX".

As stated by someone else, the K24Z2 & Z3 in the Accord utilizes iVTEC only on the intake cam, not on the exhaust cam. The only thing the exhaust cam has "special" is the "VTEC-E" feature as mentioned, in which what it does is only activates 1 exhaust valve per cylinder below 2,500 rpm, once the engine reaches 2,500 + rpm, a mechanism is activated which operates both exhaust valves.

The purpose of the "1 exhaust valve" per cylinder in low rpm is optimization of fuel efficiency and low rpm torque delivery. It's actually not a bad thing, it helps reduce emissions, more effectively uses fuel, generates more power and torque in the low rpms, and is helpful in performance applications by optimizing swirl and quench for more effective ignition which helps reduce knock, ping and predetonation. But that's a totally different conversation.

Thank you very much

Let's make it simple. There's no such thing as a "Non VTEC" 8th gen Accord. All 8th gen Accords have VTEC.

The V6 has 2 different versions: the "VCM" iVTEC found in the automatic transmission equipped V6's. And the non VCM regular VTEC (not iVTEC) V6 found in the manual transmission equipped V6's.

The 4 cylinder has 3 variations (2 of which are slight variances of the Z3): The K24Z2, and the K24Z3. The Z2 is found in the Accord sedans, in the model trims: LX, LX-P, and SE (SE is a Canada only car). The Z2 was more restricted in terms of it's ECU tuning, and the exhaust being smaller diameter than the systems on the Z3 models, as well as the muffler being more restrictive. The K24Z2 is an iVTEC engine.

All of the 4 cylinder 8th gen Accord coupes (yes, all trim levels: LX-S, EX, & EX-L, both manual and automatic transmissioned) all came equipped with the Accord tuned version of the Z3, which are all iVTEC engines. The Z3 version has a larger diameter exhaust system than the Z2, and a higher flowing muffler, and more performance oriented ECU tuning.

The other variable of performance between the Z2 & the Z3 is the transmission and the PCM tuning. The Z2 is geared a little differently, and the PCM tuning is not intended for performance, but rather for economy and efficiency.

The automatic transmission in the Z3 equipped cars is more performance oriented in the PCM tuning, and has "sportier" gear ratios.

Now, for the "3rd version" of the K24Z, being the 2nd version of the K24Z3, which is the Acura TSX version, not the Accord version. It has slightly higher compression than the Accord, different ECU tuning, and electric power steering instead of a traditional power steering pump. Further, the TSX with automatic transmission has a magnesium transmission case which is approximately 9-10 pounds lighter weight than the Accord transmission case. The TSX also comes with a performance tuned PCM and oriented transmission, and is a little more refined than the Accord's transmission.

Furthermore than that, the 2nd gen TSX ('09-'14) has the option of paddle shifters for it's version of the K24Z3 with 5 speed automatic transmission.

The other variation on the 2nd gen TSX with K24Z3 is that they had the option of a 6 speed magnesium cased manual transmission with close gear ratios.

There are other variations of the K24Z series, but not in the Accord or "Accord related platform being the TSX".

As stated by someone else, the K24Z2 & Z3 in the Accord utilizes iVTEC only on the intake cam, not on the exhaust cam. The only thing the exhaust cam has "special" is the "VTEC-E" feature as mentioned, in which what it does is only activates 1 exhaust valve per cylinder below 2,500 rpm, once the engine reaches 2,500 + rpm, a mechanism is activated which operates both exhaust valves.

The purpose of the "1 exhaust valve" per cylinder in low rpm is optimization of fuel efficiency and low rpm torque delivery. It's actually not a bad thing, it helps reduce emissions, more effectively uses fuel, generates more power and torque in the low rpms, and is helpful in performance applications by optimizing swirl and quench for more effective ignition which helps reduce knock, ping and predetonation. But that's a totally different conversation.

Sorry my ignorance but , is the k24z2 ( just bought one/accord LX ) prone to oil consumption? Thanks !

 

[Honda Virgin]

Let's make it simple. There's no such thing as a "Non VTEC" 8th gen Accord. All 8th gen Accords have VTEC.

The V6 has 2 different versions: the "VCM" iVTEC found in the automatic transmission equipped V6's. And the non VCM regular VTEC (not iVTEC) V6 found in the manual transmission equipped V6's.

The 4 cylinder has 3 variations (2 of which are slight variances of the Z3): The K24Z2, and the K24Z3. The Z2 is found in the Accord sedans, in the model trims: LX, LX-P, and SE (SE is a Canada only car). The Z2 was more restricted in terms of it's ECU tuning, and the exhaust being smaller diameter than the systems on the Z3 models, as well as the muffler being more restrictive. The K24Z2 is an iVTEC engine.

All of the 4 cylinder 8th gen Accord coupes (yes, all trim levels: LX-S, EX, & EX-L, both manual and automatic transmissioned) all came equipped with the Accord tuned version of the Z3, which are all iVTEC engines. The Z3 version has a larger diameter exhaust system than the Z2, and a higher flowing muffler, and more performance oriented ECU tuning.

The other variable of performance between the Z2 & the Z3 is the transmission and the PCM tuning. The Z2 is geared a little differently, and the PCM tuning is not intended for performance, but rather for economy and efficiency.

The automatic transmission in the Z3 equipped cars is more performance oriented in the PCM tuning, and has "sportier" gear ratios.

Now, for the "3rd version" of the K24Z, being the 2nd version of the K24Z3, which is the Acura TSX version, not the Accord version. It has slightly higher compression than the Accord, different ECU tuning, and electric power steering instead of a traditional power steering pump. Further, the TSX with automatic transmission has a magnesium transmission case which is approximately 9-10 pounds lighter weight than the Accord transmission case. The TSX also comes with a performance tuned PCM and oriented transmission, and is a little more refined than the Accord's transmission.

Furthermore than that, the 2nd gen TSX ('09-'14) has the option of paddle shifters for it's version of the K24Z3 with 5 speed automatic transmission.

The other variation on the 2nd gen TSX with K24Z3 is that they had the option of a 6 speed magnesium cased manual transmission with close gear ratios.

There are other variations of the K24Z series, but not in the Accord or "Accord related platform being the TSX".

As stated by someone else, the K24Z2 & Z3 in the Accord utilizes iVTEC only on the intake cam, not on the exhaust cam. The only thing the exhaust cam has "special" is the "VTEC-E" feature as mentioned, in which what it does is only activates 1 exhaust valve per cylinder below 2,500 rpm, once the engine reaches 2,500 + rpm, a mechanism is activated which operates both exhaust valves.

The purpose of the "1 exhaust valve" per cylinder in low rpm is optimization of fuel efficiency and low rpm torque delivery. It's actually not a bad thing, it helps reduce emissions, more effectively uses fuel, generates more power and torque in the low rpms, and is helpful in performance applications by optimizing swirl and quench for more effective ignition which helps reduce knock, ping and predetonation. But that's a totally different conversation.

ec
Thanks for the information, I have been looking for a couple hours trying to find out if my (new to me) 08 Accord Coupe has vtec only on the intake cam or on both. You provided the answer that I could find nowhere else
I have 250K on the engine and I want to change the timing chain and associated parts. Thanks!

 

[duke.seastone]

Let's make it simple. There's no such thing as a "Non VTEC" 8th gen Accord. All 8th gen Accords have VTEC. The V6 has 2 different versions: the "VCM" iVTEC found in the automatic transmission equipped V6's. And the non VCM regular VTEC (not iVTEC) V6 found in the manual transmission equipped V6's. The 4 cylinder has 3 variations (2 of which are slight variances of the Z3): The K24Z2, and the K24Z3. The Z2 is found in the Accord sedans, in the model trims: LX, LX-P, and SE (SE is a Canada only car). The Z2 was more restricted in terms of it's ECU tuning, and the exhaust being smaller diameter than the systems on the Z3 models, as well as the muffler being more restrictive. The K24Z2 is an iVTEC engine. All of the 4 cylinder 8th gen Accord coupes (yes, all trim levels: LX-S, EX, & EX-L, both manual and automatic transmissioned) all came equipped with the Accord tuned version of the Z3, which are all iVTEC engines. The Z3 version has a larger diameter exhaust system than the Z2, and a higher flowing muffler, and more performance oriented ECU tuning. The other variable of performance between the Z2 & the Z3 is the transmission and the PCM tuning. The Z2 is geared a little differently, and the PCM tuning is not intended for performance, but rather for economy and efficiency. The automatic transmission in the Z3 equipped cars is more performance oriented in the PCM tuning, and has "sportier" gear ratios. Now, for the "3rd version" of the K24Z, being the 2nd version of the K24Z3, which is the Acura TSX version, not the Accord version. It has slightly higher compression than the Accord, different ECU tuning, and electric power steering instead of a traditional power steering pump. Further, the TSX with automatic transmission has a magnesium transmission case which is approximately 9-10 pounds lighter weight than the Accord transmission case. The TSX also comes with a performance tuned PCM and oriented transmission, and is a little more refined than the Accord's transmission. Furthermore than that, the 2nd gen TSX ('09-'14) has the option of paddle shifters for it's version of the K24Z3 with 5 speed automatic transmission. The other variation on the 2nd gen TSX with K24Z3 is that they had the option of a 6 speed magnesium cased manual transmission with close gear ratios. There are other variations of the K24Z series, but not in the Accord or "Accord related platform being the TSX". As stated by someone else, the K24Z2 & Z3 in the Accord utilizes iVTEC only on the intake cam, not on the exhaust cam. The only thing the exhaust cam has "special" is the "VTEC-E" feature as mentioned, in which what it does is only activates 1 exhaust valve per cylinder below 2,500 rpm, once the engine reaches 2,500 + rpm, a mechanism is activated which operates both exhaust valves. The purpose of the "1 exhaust valve" per cylinder in low rpm is optimization of fuel efficiency and low rpm torque delivery. It's actually not a bad thing, it helps reduce emissions, more effectively uses fuel, generates more power and torque in the low rpms, and is helpful in performance applications by optimizing swirl and quench for more effective ignition which helps reduce knock, ping and predetonation. But that's a totally different conversation.

Well put...thats the best explanation of the K24v3 and the small variations of the engine I have seen. I drive a 2010 Acura TSX I4 so the K24Z3 versionTSX 5 speed with tech package (which is key since it makes it still relevant as a daily driver simply due to Bluetooth less so the nav screen but hey nice to have) Pushing 240k miles right now...just changed the coils and plugs 15k miles ago..and other than regular maintenance youd expect from 240k plus car...synthetic oil...IMO its one of the best 4 cylinders ever made. I believe on top of all of the additional features they added on the TSA k24v3 that already were mentioned...they also added strengthened internals not sure if it was thicker piston arms or cross members but it also added to the engines reliability. If this one ever kicks the bucket on me...im going to for sure look for another close model year or same with like 70 or 80k...why throw away money on a new car that is falling apart after 7 years and nothing at all serviceable

 

[duke.seastone]

Let's make it simple. There's no such thing as a "Non VTEC" 8th gen Accord. All 8th gen Accords have VTEC.

The V6 has 2 different versions: the "VCM" iVTEC found in the automatic transmission equipped V6's. And the non VCM regular VTEC (not iVTEC) V6 found in the manual transmission equipped V6's.

The 4 cylinder has 3 variations (2 of which are slight variances of the Z3): The K24Z2, and the K24Z3. The Z2 is found in the Accord sedans, in the model trims: LX, LX-P, and SE (SE is a Canada only car). The Z2 was more restricted in terms of it's ECU tuning, and the exhaust being smaller diameter than the systems on the Z3 models, as well as the muffler being more restrictive. The K24Z2 is an iVTEC engine.

All of the 4 cylinder 8th gen Accord coupes (yes, all trim levels: LX-S, EX, & EX-L, both manual and automatic transmissioned) all came equipped with the Accord tuned version of the Z3, which are all iVTEC engines. The Z3 version has a larger diameter exhaust system than the Z2, and a higher flowing muffler, and more performance oriented ECU tuning.

The other variable of performance between the Z2 & the Z3 is the transmission and the PCM tuning. The Z2 is geared a little differently, and the PCM tuning is not intended for performance, but rather for economy and efficiency.

The automatic transmission in the Z3 equipped cars is more performance oriented in the PCM tuning, and has "sportier" gear ratios.

Now, for the "3rd version" of the K24Z, being the 2nd version of the K24Z3, which is the Acura TSX version, not the Accord version. It has slightly higher compression than the Accord, different ECU tuning, and electric power steering instead of a traditional power steering pump. Further, the TSX with automatic transmission has a magnesium transmission case which is approximately 9-10 pounds lighter weight than the Accord transmission case. The TSX also comes with a performance tuned PCM and oriented transmission, and is a little more refined than the Accord's transmission.

Furthermore than that, the 2nd gen TSX ('09-'14) has the option of paddle shifters for it's version of the K24Z3 with 5 speed automatic transmission.

The other variation on the 2nd gen TSX with K24Z3 is that they had the option of a 6 speed magnesium cased manual transmission with close gear ratios.

There are other variations of the K24Z series, but not in the Accord or "Accord related platform being the TSX".

As stated by someone else, the K24Z2 & Z3 in the Accord utilizes iVTEC only on the intake cam, not on the exhaust cam. The only thing the exhaust cam has "special" is the "VTEC-E" feature as mentioned, in which what it does is only activates 1 exhaust valve per cylinder below 2,500 rpm, once the engine reaches 2,500 + rpm, a mechanism is activated which operates both exhaust valves.

The purpose of the "1 exhaust valve" per cylinder in low rpm is optimization of fuel efficiency and low rpm torque delivery. It's actually not a bad thing, it helps reduce emissions, more effectively uses fuel, generates more power and torque in the low rpms, and is helpful in performance applications by optimizing swirl and quench for more effective ignition which helps reduce knock, ping and predetonation. But that's a totally different conversation.

I drive a 2010 Acura TSX I4 so the K24Z3 versionTSX 5 speed with tech package (which is key since it makes it still relevant as a daily driver simply due to Bluetooth less so the nav screen but hey nice to have)
Pushing 240k miles right now...just changed the coils and plugs 15k miles ago and other than regular maintenance...synthetic oil...its one of the best 4 cylinders ever made. I believe on top of all of the additional features they added on the TSA k24v3 that already were mentioned...they also added strengthened internals not sure if it was thicker piston arms or cross members but it also added to the engines reliability.
If this one ever goes I am for sure getting another with like 70-90k miles...why throw money away on a new car that will be falling apart in 7 years or sooner and literally nothing user serviceable.

 

[YaBoiWulf]

I have a 2010 LXS w/ no VTEC and I've been reading all around the forums and internet about which engine I should have in my car. I've gotten different answers all around. So from what I understand the K24Z2 is the lower of the two which I assume would be mine and the VTEC i4's are the K24Z3's?

Actually, the k24z2 engine does have vtec, its actually I-vtec but that’s a different story, as far as the difference, the k24z3 engine has I-vtec cams on both the intake as well as the exhaust, whereas the k24z2 only has it on the intake, commonly called eco vtec (don’t ask me why idk, I just like vroom vroom) or single-stage vtec. The k24z3 however does have its drawbacks, as the increased position of the vtc sprocket can cause cam sensor problems. They also have different compression ratios, the k24z2 has a 10:5:1 ration whereas the z3 has either a 10:7:1 for Honda or an 11:1 for Acura tsx. As for power output they still have yet another difference, the z2 produces a stock 177 hp and as for tuning friendliness it’s a meh, but can still achieve decent power output if well modified and tuned, however the z3 produces a stock 190 hp and can be easily tuned, both have the capability for forced induction however the z3 offers more adaptability and makes it hella easier lol. Hope this helps, I’m kinda a nerd when it comes to my cars and I currently have the z2 which I’m modifying with forged internals so I’d already done my research xd.

 

[Hudouc]

the k24z3 engine has I-vtec cams on both the intake as well as the exhaust, whereas the k24z2 only has it on the intake,

Nope. Both only have VTEC on the intake side. You're thinking of the older K24A family.