Civic Si Engine Limits
Thread Starter
Registered!!
Joined: Jul 2019
Posts: 4
Likes: 0
Rep Power: 0 
Civic Si Engine Limits
Hey all, new member here. I'm on the fence about a new Civic Si and wanted to ask around before I pull the trigger on it. I intend to mod it and want as close to 300 whp as possible on stock internals. Is this possible on the new 1.5 turbo engine? When will reliability start to wane? Anything I should steer clear of? Is the 2.0 NA a better option for that kind of power? Lemme know what ya'll think
Dr Krieger of Modification
Joined: Jul 2010
Posts: 3,407
Likes: 84
From: canada
Rep Power: 228 
Re: Civic Si Engine Limits
There is more potential with an older si running a k20 or k24. Of course a turbo will be needed.
Simple displacement issue 2.4L > 1.5L
You can probably increase the 1.5 with a tune, larger injectors and a bigger turbo, but eventually you will reach the flow limit. Where as the 2.4L will have an easier/safer time, aproching a larger hp target.
Simple displacement issue 2.4L > 1.5L
You can probably increase the 1.5 with a tune, larger injectors and a bigger turbo, but eventually you will reach the flow limit. Where as the 2.4L will have an easier/safer time, aproching a larger hp target.
Joined: Aug 2003
Posts: 21,620
Likes: 1,252
From: Las Vegas, NV
Rep Power: 511 Re: Civic Si Engine Limits
Clutch and turbo will be limiting factors. Factory clutch, my understanding, at least, is garbage. I have a CVT Sport Hatch, so huge power like that is kinda out of reach for me, and I'm fine with that.
Aftermarket turbos are out there. PRL motorsports has a big turbo upgrade using various t25 turbos. IIRC, they were pushing 400whp on an Si 1.5T with stock internals. I'm almost certain (can't find their build at the moment) that they're running an e85 flex fuel kit, too. Now, their Si is pushing 615whp and runs an 11s quarter mile. The turbo upgrade from them will run you at least $2100, $1800-1900 at a minimum for the turbo, and another $300-400 since you have to run their SRI or CAI. You'd also need to spend the extra money on a custom tune using either KTuner or Hondata.
27WON also has an aftermarket turbo, built from the ground up, and designed to be a direct drop in replacement, and all you'd need is a tune (which they can supply the tuner presumably with the basemap for $550 or $650, if you wanna run KTuner or Hondata, respectively). They purposely designed it to give a delay in torque delivery down low to ease the engine into high torque band, proving to be safer on the engine. That, and with the stock turbo, power levels off after 5500RPM, whereas their turbo keeps producing to redline. Pump gas, they dropped it in without a tune and netted just 18whp. Tuned, +42whp. Running E85 untuned, +52whp, tuned +64whp. Reading their blog, they maxed it out at 29psi (because the OEM MAP started to go wonky there) with an ultimate gain of +122whp and +90tq. Everything on that blog page I linked was done on an Si, stock internals, CAI, upgraded FMIC/piping, catless DP and FP mated to a stock exhaust.
tl;dr: 300whp is definitely attainable on stock internals. Takes a bit of money and tuning, but can be done safely
Aftermarket turbos are out there. PRL motorsports has a big turbo upgrade using various t25 turbos. IIRC, they were pushing 400whp on an Si 1.5T with stock internals. I'm almost certain (can't find their build at the moment) that they're running an e85 flex fuel kit, too. Now, their Si is pushing 615whp and runs an 11s quarter mile. The turbo upgrade from them will run you at least $2100, $1800-1900 at a minimum for the turbo, and another $300-400 since you have to run their SRI or CAI. You'd also need to spend the extra money on a custom tune using either KTuner or Hondata.
27WON also has an aftermarket turbo, built from the ground up, and designed to be a direct drop in replacement, and all you'd need is a tune (which they can supply the tuner presumably with the basemap for $550 or $650, if you wanna run KTuner or Hondata, respectively). They purposely designed it to give a delay in torque delivery down low to ease the engine into high torque band, proving to be safer on the engine. That, and with the stock turbo, power levels off after 5500RPM, whereas their turbo keeps producing to redline. Pump gas, they dropped it in without a tune and netted just 18whp. Tuned, +42whp. Running E85 untuned, +52whp, tuned +64whp. Reading their blog, they maxed it out at 29psi (because the OEM MAP started to go wonky there) with an ultimate gain of +122whp and +90tq. Everything on that blog page I linked was done on an Si, stock internals, CAI, upgraded FMIC/piping, catless DP and FP mated to a stock exhaust.
tl;dr: 300whp is definitely attainable on stock internals. Takes a bit of money and tuning, but can be done safely
Re: Civic Si Engine Limits
Clutch and turbo will be limiting factors. Factory clutch, my understanding, at least, is garbage. I have a CVT Sport Hatch, so huge power like that is kinda out of reach for me, and I'm fine with that.
Aftermarket turbos are out there. PRL motorsports has a big turbo upgrade using various t25 turbos. IIRC, they were pushing 400whp on an Si 1.5T with stock internals. I'm almost certain (can't find their build at the moment) that they're running an e85 flex fuel kit, too. Now, their Si is pushing 615whp and runs an 11s quarter mile. The turbo upgrade from them will run you at least $2100, $1800-1900 at a minimum for the turbo, and another $300-400 since you have to run their SRI or CAI. You'd also need to spend the extra money on a custom tune using either KTuner or Hondata.
27WON also has an aftermarket turbo, built from the ground up, and designed to be a direct drop in replacement, and all you'd need is a tune (which they can supply the tuner presumably with the basemap for $550 or $650, if you wanna run KTuner or Hondata, respectively). They purposely designed it to give a delay in torque delivery down low to ease the engine into high torque band, proving to be safer on the engine. That, and with the stock turbo, power levels off after 5500RPM, whereas their turbo keeps producing to redline. Pump gas, they dropped it in without a tune and netted just 18whp. Tuned, +42whp. Running E85 untuned, +52whp, tuned +64whp. Reading their blog, they maxed it out at 29psi (because the OEM MAP started to go wonky there) with an ultimate gain of +122whp and +90tq. Everything on that blog page I linked was done on an Si, stock internals, CAI, upgraded FMIC/piping, catless DP and FP mated to a stock exhaust.
tl;dr: 300whp is definitely attainable on stock internals. Takes a bit of money and tuning, but can be done safely
Aftermarket turbos are out there. PRL motorsports has a big turbo upgrade using various t25 turbos. IIRC, they were pushing 400whp on an Si 1.5T with stock internals. I'm almost certain (can't find their build at the moment) that they're running an e85 flex fuel kit, too. Now, their Si is pushing 615whp and runs an 11s quarter mile. The turbo upgrade from them will run you at least $2100, $1800-1900 at a minimum for the turbo, and another $300-400 since you have to run their SRI or CAI. You'd also need to spend the extra money on a custom tune using either KTuner or Hondata.
27WON also has an aftermarket turbo, built from the ground up, and designed to be a direct drop in replacement, and all you'd need is a tune (which they can supply the tuner presumably with the basemap for $550 or $650, if you wanna run KTuner or Hondata, respectively). They purposely designed it to give a delay in torque delivery down low to ease the engine into high torque band, proving to be safer on the engine. That, and with the stock turbo, power levels off after 5500RPM, whereas their turbo keeps producing to redline. Pump gas, they dropped it in without a tune and netted just 18whp. Tuned, +42whp. Running E85 untuned, +52whp, tuned +64whp. Reading their blog, they maxed it out at 29psi (because the OEM MAP started to go wonky there) with an ultimate gain of +122whp and +90tq. Everything on that blog page I linked was done on an Si, stock internals, CAI, upgraded FMIC/piping, catless DP and FP mated to a stock exhaust.
tl;dr: 300whp is definitely attainable on stock internals. Takes a bit of money and tuning, but can be done safely
MAPerformance just blew their stock engine up at over 500HP but they think it was due to a tuning issue. Bent a rod slightly and then blew the oil pump apart.
For easy power I would go with the 1.5L. The K series is a tried and true engine with great potential but will take more to get it to 300HP.
Joined: Aug 2003
Posts: 21,620
Likes: 1,252
From: Las Vegas, NV
Rep Power: 511 Re: Civic Si Engine Limits
For the edification of us non-si people that want to increase the L15's performance, there are very few differences between the si and non-si L15 (despite them all using the L15B7 engine -- some sites list the Sport/Sport touring/So engine as L15BA).
The Si has a larger digital MAF than non-si counterparts equipped with a smaller analog sensor.
Si shares the same turbo as the CRV. It's literally the same size as the non-Si variant, but has different impellers on the CHRA that produce more boost for the same exhaust flow. In fact, I think the only difference is the exhaust wheel side. I'll have to double-check that one.
Engine-internals, the Si has slightly beefier rods (which have been proven to fit into non-Si engines) and pistons with a lower compression ratio (10.3:1 vs the non-Si 10.6:1). I'm assuming this lower CR is to run more boost a bit safer.
So engine rated at 205hp. Sport/ST engine at 180, all other non-Si engines at 174.
Anyways, back on topic. Lol
The Si has a larger digital MAF than non-si counterparts equipped with a smaller analog sensor.
Si shares the same turbo as the CRV. It's literally the same size as the non-Si variant, but has different impellers on the CHRA that produce more boost for the same exhaust flow. In fact, I think the only difference is the exhaust wheel side. I'll have to double-check that one.
Engine-internals, the Si has slightly beefier rods (which have been proven to fit into non-Si engines) and pistons with a lower compression ratio (10.3:1 vs the non-Si 10.6:1). I'm assuming this lower CR is to run more boost a bit safer.
So engine rated at 205hp. Sport/ST engine at 180, all other non-Si engines at 174.
Anyways, back on topic. Lol
Thread Starter
Registered!!
Joined: Jul 2019
Posts: 4
Likes: 0
Rep Power: 0 Re: Civic Si Engine Limits
Thanks for the responses everyone. I've heard from somebody else also that the stock clutch is no good after just a hair more power. This definitely makes me feel better about purchasing it though. I was afraid with such a small engine there would not be much head room to work with. Now I'm just trying to figure out a good upgrade path.
Thread
Thread Starter
Honda Civic Forum
Replies
Last Post
2016Touring
10th Generation Civic 2016-2021
5
Mar 25, 2018 01:11 PM
