Engine mods for K20C2?

Romeoridgee

Honda Dealer Tech.
First Name
Rob
Joined
Mar 7, 2019
Messages
389
Reaction score
144
Location
Maryland
Car(s)
19 Sport. 17 EX-T. 16 EX-T. 12 Accord EX. 08 LX
Vehicle Showcase
1
Country flag
1.5 compression ratio is 10.3
2.0 compression ratio is 10.8
Not that much of a difference…
Drob (no disrespect to him) hasn’t tuned a boosted c2.
The slow fc2 probably has stock engine and trans, and no return fuel system (reason for heavy fluctuating afr’s). I talked to him and his mechanic did everything which makes be believe he wasn’t very knowledgeable in what had to be done exactly, especially with the tuning. I will not deny the information he was told was incorrect.
E85 kit can be utilized, with separate e85 tune and ethanol content gauge, upgraded port injectors, just can’t be hooked up to the ecu and alter/change maps.
There is no record of what the c2 can’t handle so you can’t say:
It is very much a challenge to add a turbo or supercharger due to stock ECU limitations, stock bottom end on the C2 not being able to handle more than a few lb of boost to begin with.
Advertisement

 

rwk226

Senior Member
First Name
Ryan
Joined
May 11, 2021
Messages
360
Reaction score
316
Location
Senatobia, Mississippi
Car(s)
2018 Honda Civic EX-L Hatchback (CVT)
Build Thread
Link
Vehicle Showcase
1
Country flag
1.5 compression ratio is 10.3
2.0 compression ratio is 10.8
Not that much of a difference…
Drob (no disrespect to him) hasn’t tuned a boosted c2.
The slow fc2 probably has stock engine and trans, and no return fuel system (reason for heavy fluctuating afr’s). I talked to him and his mechanic did everything which makes be believe he wasn’t very knowledgeable in what had to be done exactly, especially with the tuning. I will not deny the information he was told was incorrect.
E85 kit can be utilized, with separate e85 tune and ethanol content gauge, upgraded port injectors, just can’t be hooked up to the ecu and alter/change maps.
There is no record of what the c2 can’t handle so you can’t say:
Now you're bringing back up the L15, in a c2 thread... stick to topic.

Joking, but in all seriousness: L15 is a motor built for boost. Forged internals, and even though the HBs have weaker rods than the standard Sedan/Coupe L15s, it is still stronger than what the C2 has. Honda did not create this motor for boost, but I believe most well built motors to begin with (Honda doesn't make bad engines usually), regardless of whether they're meant for boost or not / have weaker internals, could probably handle a few lb of boost as long as tune is set conservative and focus on reliability over power.
Drob probably hasn't a) had anyone want to boost a c2, or b) he's refused to for whatever reason, but only he can really answer that question.
L15B7 has 10.6:1 in non-Si and 10.3:1 in Si, correct. But again, motor designed around boost vs not. Maybe if you could upgrade rods and reinforce the block, then you could definitely make more than single digit lb of boost.
If there are aftermarket injectors that would support e85, that might be a really good option for the C2, but you might have to replace fuel lines and do some other work to make sure you don't cause any damage.

If someone simply wants a project to work on, this would be a good one. I do wish we knew more about the C2, because you are right when you say we simply don't have enough to go off of. One or two people who claim to have boosted their C2 without a proper breakdown of what all was done, what parts were used, what work was done, and long-term reliability information simply isn't enough info to say anything. What little we do know is not exactly good news or encouraging, but maybe as these cars depreciate, someone might buy one and do the extensive testing and figure out something. This platform simply didn't have the same promise of potential as L15 has, which is why people (including myself) so quickly and easily say go for L15 instead, and while that may come across as insensitive or ignorant, I personally don't say it to mean either.
 

charleswrivers

Senior Member
First Name
Charles
Joined
Nov 3, 2017
Messages
3,689
Reaction score
4,353
Location
Kingsland, GA
Car(s)
'14 Odyssey, '94 300zx, 2001 F-150, 2018 Si sedan
Vehicle Showcase
1
Country flag
1.5 compression ratio is 10.3
2.0 compression ratio is 10.8
Not that much of a difference…
Drob (no disrespect to him) hasn’t tuned a boosted c2.
The slow fc2 probably has stock engine and trans, and no return fuel system (reason for heavy fluctuating afr’s). I talked to him and his mechanic did everything which makes be believe he wasn’t very knowledgeable in what had to be done exactly, especially with the tuning. I will not deny the information he was told was incorrect.
E85 kit can be utilized, with separate e85 tune and ethanol content gauge, upgraded port injectors, just can’t be hooked up to the ecu and alter/change maps.
There is no record of what the c2 can’t handle so you can’t say:
Compressions being close when comparing a port injection engine to a DI engine should be taken with a grain of salt. DI has allowed modern turbo cars run far higher compression than in the past. C2s gained a little compression over A3s. It’s one of the few differences on paper to help efficiency in the intervening years.
 

civil-k-2020

Member
First Name
Alex
Joined
Nov 20, 2020
Messages
26
Reaction score
13
Location
San Diego
Car(s)
2020 Civic LX
Country flag
Now you're bringing back up the L15, in a c2 thread... stick to topic.

Joking, but in all seriousness: L15 is a motor built for boost. Forged internals, and even though the HBs have weaker rods than the standard Sedan/Coupe L15s, it is still stronger than what the C2 has. Honda did not create this motor for boost, but I believe most well built motors to begin with (Honda doesn't make bad engines usually), regardless of whether they're meant for boost or not / have weaker internals, could probably handle a few lb of boost as long as tune is set conservative and focus on reliability over power.
Drob probably hasn't a) had anyone want to boost a c2, or b) he's refused to for whatever reason, but only he can really answer that question.
L15B7 has 10.6:1 in non-Si and 10.3:1 in Si, correct. But again, motor designed around boost vs not. Maybe if you could upgrade rods and reinforce the block, then you could definitely make more than single digit lb of boost.
If there are aftermarket injectors that would support e85, that might be a really good option for the C2, but you might have to replace fuel lines and do some other work to make sure you don't cause any damage.

If someone simply wants a project to work on, this would be a good one. I do wish we knew more about the C2, because you are right when you say we simply don't have enough to go off of. One or two people who claim to have boosted their C2 without a proper breakdown of what all was done, what parts were used, what work was done, and long-term reliability information simply isn't enough info to say anything. What little we do know is not exactly good news or encouraging, but maybe as these cars depreciate, someone might buy one and do the extensive testing and figure out something. This platform simply didn't have the same promise of potential as L15 has, which is why people (including myself) so quickly and easily say go for L15 instead, and while that may come across as insensitive or ignorant, I personally don't say it to mean either.
I'm pretty sure Honda has used forged internals for all it's cars, I don't see why they would change that for the C2. But I agree, I would focus on reliability and a conservative build to start out with.
 

gtman

Senior Member
First Name
Mitch
Joined
Oct 27, 2015
Messages
12,203
Reaction score
17,106
Location
USA
Website
www.civicx.com
Car(s)
2017 Cosmic Blue EX-L Sedan
Vehicle Showcase
2
Country flag
CVTs as the weak link was mentioned earlier and the question was is the CVT mated to both engines identical. They are not. The turbo engines use a beefed up CVT that was original used in the last gen Accords. The one mated to the C2 is a refined version of the unit that was used in the 9th gen Civics.

Here's the writeup taken from the 2016 Civic Press Kit:

"Two different CVT transmissions are offered in the new Civic to best suit the power output and operating characteristics of each available engine.

The Civic LX and EX which are powered by the 2.0-liter engine offer a CVT (available in the LX and standard in the EX) that is a refined version of the CVT that was offered in the previous generation Civic.
It features a retuned torque converter, and a new generation of G-Design shift logic.

Turbo Civic models offer a CVT that is an evolution of the CVT transmission that is offered in Accord 4-cylinder models. In this application, the transmission's final gear ratio is 4.69-percent taller than the Accord CVT on which it's based, to allow for lower engine rpm while cruising. A new generation of G-Design shift logic aids acceleration and has a more familiar driving feel. A new turbine twin-damper design for the torque converter provides tighter control and helps reduce turbocharger lag as the vehicle accelerates."
 

rwk226

Senior Member
First Name
Ryan
Joined
May 11, 2021
Messages
360
Reaction score
316
Location
Senatobia, Mississippi
Car(s)
2018 Honda Civic EX-L Hatchback (CVT)
Build Thread
Link
Vehicle Showcase
1
Country flag
I'm pretty sure Honda has used forged internals for all it's cars, I don't see why they would change that for the C2. But I agree, I would focus on reliability and a conservative build to start out with.
My perspective is, they used the K20C2 as the base-model engine for a reason. It is clearly cheaper to manufacture a C2 than it is a L15B7, hence why they made it. Maybe it's the same block as a K20C1(maybe???) or maybe similar, but they picked it as a base-model motor for a reason. Cheap, easy to make. They cut cost somewhere with it. Note I am no expert on these motors so I simply am making assumptions based on what I know, but that's why I came across as skeptical of boosting this motor before.
 

rwk226

Senior Member
First Name
Ryan
Joined
May 11, 2021
Messages
360
Reaction score
316
Location
Senatobia, Mississippi
Car(s)
2018 Honda Civic EX-L Hatchback (CVT)
Build Thread
Link
Vehicle Showcase
1
Country flag
CVTs as the weak link was mentioned earlier and the question was is the CVT mated to both engines identical. They are not. The turbo engines use a beefed up CVT that was original used in the last gen Accords. The one mated to the C2 is a refined version of the unit that was used in the 9th gen Civics.

Here's the writeup taken from the 2016 Civic Press Kit:

"Two different CVT transmissions are offered in the new Civic to best suit the power output and operating characteristics of each available engine.

The Civic LX and EX which are powered by the 2.0-liter engine offer a CVT (available in the LX and standard in the EX) that is a refined version of the CVT that was offered in the previous generation Civic.
It features a retuned torque converter, and a new generation of G-Design shift logic.

Turbo Civic models offer a CVT that is an evolution of the CVT transmission that is offered in Accord 4-cylinder models. In this application, the transmission's final gear ratio is 4.69-percent taller than the Accord CVT on which it's based, to allow for lower engine rpm while cruising. A new generation of G-Design shift logic aids acceleration and has a more familiar driving feel. A new turbine twin-damper design for the torque converter provides tighter control and helps reduce turbocharger lag as the vehicle accelerates."
Great info, thanks for sharing! Wasn't aware there were two different CVT options here. Looks like the last gen Civic CVTs did not hold up well with higher power than stock, which is just a bit less than what the current c2 makes...
 

gtman

Senior Member
First Name
Mitch
Joined
Oct 27, 2015
Messages
12,203
Reaction score
17,106
Location
USA
Website
www.civicx.com
Car(s)
2017 Cosmic Blue EX-L Sedan
Vehicle Showcase
2
Country flag

gtman

Senior Member
First Name
Mitch
Joined
Oct 27, 2015
Messages
12,203
Reaction score
17,106
Location
USA
Website
www.civicx.com
Car(s)
2017 Cosmic Blue EX-L Sedan
Vehicle Showcase
2
Country flag
It doesn't say anything about max power, just adjustments for a smoother driving experience. Again, stop comparing to the L15 this is not that thread
To clarify, I read it differently.

"Two different CVT transmissions are offered in the new Civic to best suit the power output and operating characteristics of each available engine"

Knowing that the turbo is the higher output motor this says to me that the CVT they used in the C2 isn't as capable of handling higher power/torque.
 
Last edited:

civil-k-2020

Member
First Name
Alex
Joined
Nov 20, 2020
Messages
26
Reaction score
13
Location
San Diego
Car(s)
2020 Civic LX
Country flag
This is not the thread topic. Stay on topic or get off.
My last post in the thread but to clarify, I read it differently.


Knowing that the turbo is the higher output motor this says to me that the CVT they used in the C2 isn't as capable of handling higher power/torque.
Sounds like this still needs to be tested. Show me the results and I will believe you.
 

Romeoridgee

Honda Dealer Tech.
First Name
Rob
Joined
Mar 7, 2019
Messages
389
Reaction score
144
Location
Maryland
Car(s)
19 Sport. 17 EX-T. 16 EX-T. 12 Accord EX. 08 LX
Vehicle Showcase
1
Country flag
The c2 internals would hold the same power as any other K series would. Of Course if you drop high performance pistons, rods and bearings with wet sleeves, valve train, and arp head studs with it obviously it would hold more power.

Knowing that the turbo is the higher output motor this says to me that the CVT they used in the C2 isn't as capable of handling higher power/torque.
It’s called the higher output motor BECAUSE it has a turbo not it, not because the engine can handle more power.
 

charleswrivers

Senior Member
First Name
Charles
Joined
Nov 3, 2017
Messages
3,689
Reaction score
4,353
Location
Kingsland, GA
Car(s)
'14 Odyssey, '94 300zx, 2001 F-150, 2018 Si sedan
Vehicle Showcase
1
Country flag
Last gen was R18s… nothing to do with an L15B7. There were turbo versions in the wild as the aftermarket supported it. I’m sure the gen 9 forums have discussed turbocharging a CVT-equipped R18 to death. I used to frequent them when I had my ‘15 but I never followed many R18 threads.
 

gtman

Senior Member
First Name
Mitch
Joined
Oct 27, 2015
Messages
12,203
Reaction score
17,106
Location
USA
Website
www.civicx.com
Car(s)
2017 Cosmic Blue EX-L Sedan
Vehicle Showcase
2
Country flag
It’s called the higher output motor BECAUSE it has a turbo not it, not because the engine can handle more power.
I was referring to the different CVTs being capable of handling more or less power (in response to an earlier question), not the engines.
 

rwk226

Senior Member
First Name
Ryan
Joined
May 11, 2021
Messages
360
Reaction score
316
Location
Senatobia, Mississippi
Car(s)
2018 Honda Civic EX-L Hatchback (CVT)
Build Thread
Link
Vehicle Showcase
1
Country flag
It doesn't say anything about max power, just adjustments for a smoother driving experience. Again, stop comparing to the L15 this is not that thread
In the post you quoted here, I never once mentioned the L15. I mentioned LAST GEN Civics which didn't have L15, so not sure where you're getting that from based off the quote you used to bash me...

The c2 internals would hold the same power as any other K series would. Of Course if you drop high performance pistons, rods and bearings with wet sleeves, valve train, and arp head studs with it obviously it would hold more power.


It’s called the higher output motor BECAUSE it has a turbo not it, not because the engine can handle more power.
I would LOVE to see your evidence/proof that C2 internals are capable of the same power as previous K series motors.

It is clear there are two different CVT options available, that one is modified from the Accord 2.4l last gen, and one from the Civic 1.8l last gen. Each CVT had its own purpose and managed different power outputs (185hp 184tq from Accord vs 143hp and 129tq from Civic both last Gens), so based on the articles it is safe to assume that the CVT in the C2 is related to the 1.8L Civic CVT of last gen, but "improved".

This is not the thread topic. Stay on topic or get off. These kinds of posts just take up space that make it difficult for C2 people to get the info they need
I replied to your post with my comment about my theory on why C2 internals MIGHT not be as stout as you guys think. If me stating a theory on why C2 internals are not as capable as imagined is not pertinent to a thread discussing ENGINE MODS (pretty sure pistons, valvetrain, etc. are considered part of the engine) for C2s, then I guess we are in two separate worlds.

I don't get the hostility from you two at all, we've been nothing but helpful and I explained my position very well, while also offering a lot of different information and evidence to support everything I've said. With you two being rude and name calling the majority of your posts, I am done with this discussion. The information I've given is common knowledge and easily searchable on both the forums and the Internet. Props to whoever cracks the code of the C2.
 

Civic_rob

Senior Member
First Name
Robert
Joined
May 13, 2019
Messages
209
Reaction score
169
Location
Virginia
Car(s)
2018 Civic LX-P
Build Thread
Link
Vehicle Showcase
1
Country flag
1.5 compression ratio is 10.3
2.0 compression ratio is 10.8
Not that much of a difference…
Drob (no disrespect to him) hasn’t tuned a boosted c2.
The slow fc2 probably has stock engine and trans, and no return fuel system (reason for heavy fluctuating afr’s). I talked to him and his mechanic did everything which makes be believe he wasn’t very knowledgeable in what had to be done exactly, especially with the tuning. I will not deny the information he was told was incorrect.
E85 kit can be utilized, with separate e85 tune and ethanol content gauge, upgraded port injectors, just can’t be hooked up to the ecu and alter/change maps.
There is no record of what the c2 can’t handle so you can’t say:
The compression ratio for the Type R is actually 9:8 with the K20C2 (NA Base) at 10:8. As far as the transmission yes that will be a point of weakness that will have to be addressed on anything over 250hp which seems to be the limit for the L15B motors. I'm doing some guestimation and saying the K20C2 will be able to handle the boost without an issue from a motor perspective but the transmission (CVT namely) will begin to score on the belt and eventually slip.

I wrote to this subject in this thread since I've been working with my K20C2 getting it prepped for some power adders in a safe and somewhat reliable way.

Limiting the torque figures, you should be able to still achieve that higher horsepower number without lighting up your trans. (Think quick versus fast; a quick car means shortest time where fast means speed). That goldilocks zone will need to be fine tuned on higher boost levels if that was the route someone went. I'd be more concerned about the area under the hp/tq curve rather than the peak numbers. More area = more powerful car. My specific modal has the following hp/tq curve based on the engine rpm here.

The KTuner alone adds ~25hp peak and greatly expands the area under the curve. With peak power being at ~4500rpm or so, with a nitrous shot it should still climb after that even though the peak has already been met. A 50shot I would expect to add a larger area under the curve (I plan on having it kick in at 5300rpm-6500 with anything higher having a cutoff since the engine on the tune now will rev to 7000). With the turbo, there's the issue of more immediate torque and having spinning the turbo since it would be built into the system. The pic attached is from the KTuner website for the K20C2 base tune they offer with no other modifications.

If there was a Kraftwerks supercharger that I could use instead that had a bolt on fitment more or less that's what I would've went with since superchargers (most) are belt driven and sap some of the hp/tq to make more hp/tq. It would be a better complement than a turbo even if they are less efficient. Supposedly there was some guy who was trying to supercharge his K20C2 but honestly I don't know what people are actually going to commit to a project like that or what people just like to say wild things with the hopes that it will be an easy 2 hour job.

Also port-injected for the K20C2 is a godsend over the Type R. Granted there's no flex fuel kit (not much gain for an NA motor anyways) but I think they can run the stock injectors for E85 whereas the 2.slow gang can't since our injectors are different? I'm not 100% sure on that specifically but an E85 kit on a boosted K20C2 would go very nicely. A water meth kit would be even better but I certainly would not want to be the tuner tuning it!

Hope this clarifies some things for everyone and let me know if anything I posted was incorrect or if you have questions about! I try to know everything I can about the K20C2 but sometimes there are things I forget or say wrong.

-Rob

K20C2GAINS.jpg
 
Advertisement

 
Advertisement
Top