Building for 400WHP

Vincent@27WON

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One of the most popular blogs on our website is “How to make 300 hp on a 10th generation Civic L15”. It has successfully guided many of you to this milestone in performance. With full bolt-ons and some ethanol-blended fuel, we find the majority pull in the 310-340 whp range which is solid numbers for a fairly small 1.5L 4-banger.

BUT LIKE ALL THINGS IN LIFE WE LOOK FORWARD TO THE NEXT PROGRESSION. SO WHAT COMES AFTER MAKING THE 300HP MARK? WELL MAKING 400HP OF COURSE.

However, going from 300whp to 400whp requires more effort and time than it did going from 200whp to 300whp. The parts needed and the skills required are greater. Today we are going to dive into that in some detail.

Honda Civic 10th gen Building for 400WHP 1678311693831


I want to preface this by saying there is no specific magic # of horsepower that the stock bottom end can hold before bad things happen. And by bad things I mean - “my engine blew up”. We have seen engines let go as little as 280 and have seen a few get pushed over the 400 mark with correct tuning and fuel upgrades. That being said, when customers call us and tell us how much power they get on the stock engine my answer is always the same. Experience tells us that around 375 whp is when one should consider a built engine. Again this is not to say that it will run all day at 374 or blow up at 376. This is to say that as you get closer to that power range you should realize that you are on borrowed time. Don’t be surprised if she happens to let go when you get up in this range. Let’s talk about how to avoid a blown motor.

Honda Civic 10th gen Building for 400WHP 1678311706425


OUR 10TH GEN SI HAS LIVED HAPPILY AND HEALTHY IN THE ~350 WHP RANGE FOR A WHILE BUT IT’S TIME FOR 400+. OUR GOAL IS A SOLID ~435 DAILY ON SETUP CAPABLE OF DOING 500WHP. TO GET TO THAT GOAL AN ENGINE BUILD IS IN ORDER. WHILE STILL WORKING ON AND DAILY DRIVING OUR 2018 CIVIC SI; WE SOURCED A SPARE L15B7.

Honda Civic 10th gen Building for 400WHP 1678311727538



Our goals for the build were simple; make an engine that could easily support 500hp and do it with off-the-shelf parts. We didn’t want a build that would require custom this or really exotic that. It was to be a build for the people. A build that most any well-equipped machine shop could do and with parts you can easily get.

The recipe was quite easy in terms of beefier internals: forged connecting rods, forged pistons, head studs, and valve springs. Nearly everything else used was OEM parts and of course a full suite of 27WON goodies for all the power adders.

Honda Civic 10th gen Building for 400WHP 1678311739890



We know that on these cars the biggest hurdle to 400+ HP after the engine is fuel. The OEM fuel system simply can’t support 350+ HP. An upgrade is required. We will share details about that with you in a later blog.

Before you can start building a new engine you need to teardown the old one, so check out this sweet video and see ours done in 2 minutes flat!

Will post some follow up write ups later
 

borcth

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:popcorn:

I love this kind of breakdown, research and science stuff. I like to learn. Keep it coming 27won!
 

Ap1 George

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Are you going to start offering built L15Bs soon? I may just need one 🤔
 

Redwing

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Unfortunately, (or not) I am in dire need of this thread. I have been scouring the internet for reliable 375+ hp in the L15B form factor. I have been looking everywhere for off-the-shelf parts to make my build happen. At this point, I just don't want to end up sacrificing my first born child, my kidney, and what's left of my sanity for more POWER.

At my current depth down the rabbit hole, I have been eying the Skunk2 Ultra cams, stuff for a built bottom-end, 7500+ RPM redline, Drop-in Big Turbos (like the W2) and I don't know what for the fuel system. I know there are a lot of supporting mods I will need for reliability reasons: i.e. head studs, valve springs, a built transmission, and so much more...

Something of note is that I have no intention of using E85 fuel blends. I know that means I will be leaving a lot of performance on the table, but I do not plan on utilizing E85 for a number of reasons like the already established fueling constraints, excess reliability stuff, and the fact I am blessed with plentiful 93+ octane fuel among other things.

TLDR: Thankyou Vincent and the whole 27WON team for pushing and giving more love to us die hard 1.5L fans!!!
 


Redwing

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P.S. - if ya wouldn't mind... could someone give me advice on how cams (like the Skunk2's) would do in higher RPM's on this platform? I've looked at the advertised specs and RPM range improvements over stock, but I am a bit skeptical. Wouldn't there be a bottleneck in the head/exhaust ports that would make the improvements with a cam close to negligible? (Skunk2 advertises testing +30hp/lb-ft over stock... which is not close to negligible...) In addition, if the cams do in fact work as described, could they help improve spooling characteristics therein by reducing lag for a larger turbo (like the W2)?

P.P.S - Sorry if this is not the right place for this question, but I don't know who will entertain my lunacy. :D
 

ChefRyeSi

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Unfortunately, (or not) I am in dire need of this thread. I have been scouring the internet for reliable 375+ hp in the L15B form factor. I have been looking everywhere for off-the-shelf parts to make my build happen. At this point, I just don't want to end up sacrificing my first born child, my kidney, and what's left of my sanity for more POWER.

At my current depth down the rabbit hole, I have been eying the Skunk2 Ultra cams, stuff for a built bottom-end, 7500+ RPM redline, Drop-in Big Turbos (like the W2) and I don't know what for the fuel system. I know there are a lot of supporting mods I will need for reliability reasons: i.e. head studs, valve springs, a built transmission, and so much more...

Something of note is that I have no intention of using E85 fuel blends. I know that means I will be leaving a lot of performance on the table, but I do not plan on utilizing E85 for a number of reasons like the already established fueling constraints, excess reliability stuff, and the fact I am blessed with plentiful 93+ octane fuel among other things.

TLDR: Thankyou Vincent and the whole 27WON team for pushing and giving more love to us die hard 1.5L fans!!!
Axion fuel system is the best, safest and easiest to install. No BS wiring bypass stuff. $1600. Get it
 

ChefRyeSi

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P.S. - if ya wouldn't mind... could someone give me advice on how cams (like the Skunk2's) would do in higher RPM's on this platform? I've looked at the advertised specs and RPM range improvements over stock, but I am a bit skeptical. Wouldn't there be a bottleneck in the head/exhaust ports that would make the improvements with a cam close to negligible? (Skunk2 advertises testing +30hp/lb-ft over stock... which is not close to negligible...) In addition, if the cams do in fact work as described, could they help improve spooling characteristics therein by reducing lag for a larger turbo (like the W2)?

P.P.S - Sorry if this is not the right place for this question, but I don't know who will entertain my lunacy. :D
Dont get the cams. Our cars arent made for high RPM. These are low-mid end torque monsters
 

Redwing

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Dont get the cams. Our cars arent made for high RPM. These are low-mid end torque monsters
Thankyou for pointing me in a direction, but I want to reduce the peak torque of my engine if at all possible. I know these little 1.5's are capable of making ridiculous low end torque, but I also know motor internals, trans, gears, axles and everything else doesn't like that ridiculous torque.

A large part of my build is to stretch out the powerband as far as possible. I already know I will need to be going to a higher redline, its now about far I can stretch that powerband out. Do you think those cams will help with that?
 

ChefRyeSi

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Thankyou for pointing me in a direction, but I want to reduce the peak torque of my engine if at all possible. I know these little 1.5's are capable of making ridiculous low end torque, but I also know motor internals, trans, gears, axles and everything else doesn't like that ridiculous torque.

A large part of my build is to stretch out the powerband as far as possible. I already know I will need to be going to a higher redline, its now about far I can stretch that powerband out. Do you think those cams will help with that?
Dont get the cams. Get a drop in turbo for that if anything. Or just get a conservative custom tune.
 


ChefRyeSi

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Thankyou for pointing me in a direction, but I want to reduce the peak torque of my engine if at all possible. I know these little 1.5's are capable of making ridiculous low end torque, but I also know motor internals, trans, gears, axles and everything else doesn't like that ridiculous torque.

A large part of my build is to stretch out the powerband as far as possible. I already know I will need to be going to a higher redline, its now about far I can stretch that powerband out. Do you think those cams will help with that?
Anything above 280-ish tq is pushing it. The internals will break before anything else, so dont worry about that stuff
 
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Vincent@27WON

Vincent@27WON

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Vincent@27WON

Vincent@27WON

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Axion fuel system is the best, safest and easiest to install. No BS wiring bypass stuff. $1600. Get it
Can you post a link to that kit? I am not familiar with it.
 
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Vincent@27WON

Vincent@27WON

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Thankyou for pointing me in a direction, but I want to reduce the peak torque of my engine if at all possible. I know these little 1.5's are capable of making ridiculous low end torque, but I also know motor internals, trans, gears, axles and everything else doesn't like that ridiculous torque.

A large part of my build is to stretch out the powerband as far as possible. I already know I will need to be going to a higher redline, its now about far I can stretch that powerband out. Do you think those cams will help with that?
If you are looking to stretch out the powerband as you say, so rev out to like 7500-8000 rpm then you will for sure want the valve springs and retainers and in your case the upgraded oil pump.

Getting north of 400hp on just the 93 octane will not be easy. it will require a lot of fuel. Are you open to the idea of port injection or are you trying to stick with GDI only?
 

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