1.5T Power Metrics & Limitations for 1.5L Turbo (Non Si models)

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Hollywoo0220

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It was PRL that said that indeed and is still the only one that says that.27Won says it is a restriction ,and others as wel.Most tuners i know around here also say it's a restriction.
Imo they never tested it properly, a full (larger) exhaust vs a stock exhaust would be a good test.Unbolting a stock exhaust after the front pipe isn't.
For me the best front pipe or downpipe would be tapered in size .For example starting at 3" at the turbo flange going true the cat into 2.75" then into the front pipe going from 2.75" to 2.5" .After that the exhaust can go from 2.5" to 2.36" and end up into a twin 2" or single 2.36" pipe. This keeps the exhaust pulses going and exhaust velocity up .Unbolting after the front pipe ,slows down the exhaust pulses into a very large area which could also mean hp loss.
You do understand (if you read the metrics) that the stock set-up is already tapered. You aren’t making the power to surpass the stock exhaust system w/o an upgraded turbo.
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It was PRL that said that indeed and is still the only one that says that.27Won says it is a restriction ,and others as wel.Most tuners i know around here also say it's a restriction.
Imo they never tested it properly, a full (larger) exhaust vs a stock exhaust would be a good test.Unbolting a stock exhaust after the front pipe isn't.
For me the best front pipe or downpipe would be tapered in size .For example starting at 3" at the turbo flange going true the cat into 2.75" then into the front pipe going from 2.75" to 2.5" .After that the exhaust can go from 2.5" to 2.36" and end up into a twin 2" or single 2.36" pipe. This keeps the exhaust pulses going and exhaust velocity up .Unbolting after the front pipe ,slows down the exhaust pulses into a very large area which could also mean hp loss.
I understand your thinking. I tried this philosophy on my 2015 Honda Fit. Even made a thread about it ~~~> Myxal Reducing Exhaust Diameter And another thread, longer, at FitFreak ~~~> Myxal Reducing Diameter Exhaust (Fitfreak)

In the meantime, since I have a PRL down pipe attached to the stock front pipe and stock exhaust (That are both tapered from the factory), I guess just changing out the downpipe would fit this thinking in a sense, right? :headbang::)
 

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I understand your thinking. I tried this philosophy on my 2015 Honda Fit. Even made a thread about it ~~~> Myxal Reducing Exhaust Diameter And another thread, longer, at FitFreak ~~~> Myxal Reducing Diameter Exhaust (Fitfreak)

In the meantime, since I have a PRL down pipe attached to the stock front pipe and stock exhaust (That are both tapered from the factory), I guess just changing out the downpipe would fit this thinking in a sense, right? :headbang::)
I don't know what size the PRL downpipe is on the exit ,but they start at 3" afaik. I know Wagner tuning also makes the downpipe for the fk2 type-r (which is the same engine as the FK8) and they start at 4" and exit in 3" .They also use the highly reputable HJS catalytic converters which are designed this way . (Any properly designed cat converter has a wide(r) entry taper and a shallow(er) exit taper)
 
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It is the Exhaust Turbine of the stock turbos gents that is the restriction. Once the turbo is upgraded the flow stream (at that point) can be improved.
Higher octane fuel and a proper tune can achieve that on the stock system. An intercooler is beneficial when consistency is desired.
 
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Good stuff. Everything I've seen on our turbos has shown they've been either HP or LP variants of TD025s. Could they actually be a hybrid of the two? (shrug) maybe. I'd heard the Accords with their K20C4s also had conflicting info as to what turbo that had compared to what Honda advertised.

TD025Tag.jpg
IMG_20171230_135417.jpg
UfG70eh.jpg
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IMG_20180121_110129_778.jpg


In the end... we got what we got. It's responsible for a quick spool when you get rid of the slow ramp up and makes for rapid massive midrange power... it just can't flow enough to make the top end power match other competitors that have 2L engines mated to ~TD04 sized turbos that are tuned on pump gas.

I still am very interested if Honda decides to recycle the L15 engine if they did testing with a larger turbo to make well more the 200 hp but intentionally gimped gen 10 to leave a little more on the table for a gen 11 car. We're still a couple years out from knowing. Unless Honda is looking at variable compression or HCCI, I'm not sure what other tricks they have to improve economy on the L-engine for gen 11. I thought the number to reach was 50 mpgs by 2025. We'll have had the Si stuck at ~200 flywheel HP for over 20 years by the time gen 11 hits. I'm not sure where Honda will go next. I imagine they'll target more efficiency before power.
@charleswrivers
Yes, I agree with you wholeheartedly. The Gen11 will have an increased Volumetric Efficiency and more than likely remain at the same power levels - thus increase fuel economy.
As I understand, Mazda’s SkyActiveX (when released later this Fall’19) is a high compression combustion ignition and will have an incredible VE. Basically a supercharged system with responsiveness, power production, and fuel economy.
 


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It is the Exhaust Turbine of the stock turbos gents that is the restriction. Once the turbo is upgraded the flow stream (at that point) can be improved.
Higher octane fuel and a proper tune can achieve that on the stock system. An intercooler is beneficial when consistency is desired.

Understood! With this in mind, I'll be keeping the stock turbo. Already using higher octane, a tune (Base) and upgraded intercooler. Getting fairly close to what people are saying the torque limits are with the CVT (240ft-lbs or thereabouts). No point getting a bigger to go past this point.
 
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Understood! With this in mind, I'll be keeping the stock turbo. Already using higher octane, a tune (Base) and upgraded intercooler. Getting fairly close to what people are saying the torque limits are with the CVT (240ft-lbs or thereabouts). No since getting a bigger to go past this point.
Well...
If you are yet using one of the BASE tunes (probably the 21psi)? You are not nearing the high-end limitation of the CVT; nor @/or near 240lb/ft. You will need to custom tune for that and require a percentage of E85. The only way to keep the torque curve at a higher RPM is to upgrade the turbo (to prolong the CVT). Me personally, I wouldn't venture into that realm.
With your DP, you are probably feeling a tad (400RPM) slower in the lower RPM, until your exhaust pressure builds for torque - but, running a bit smoother in the Mid all the way to 5600rpm. The Intercooler is truly the way to go to recover from heat soak faster. :)
 
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Well...
If you are yet using one of the BASE tunes (probably the 21psi)? You are not nearing the high-end limitation of the CVT; nor @/or near 240lb/ft. You will need to custom tune for that and require a percentage of E85.
I only based this off my recent trap speeds and using online 1/4 mile calculators. Like THIS or THIS ONE. These probably aren't entirely accurate but they are guides. Either way, it's all good info. I appreciate your knowledge and input on this subject matter.
 

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Stock with 2.5" exhaust https://www.civicx.com/threads/apexi-n1-x-exhaust-for-hatchback-review-with-dyno.32041/

Post from Kytos https://www.civicx.com/threads/ktun...p-switching-and-more.35199/page-3#post-592596
First dyno is stock (stock ecu) with 2.5" exhaust And k&n drop in filter
https://civicx.club/t/votacion-de-estimacion-de-potencia-stage-1-y-stage-2-ktuner/1875/10

TDI North (UK) tuning this fk7 stock car with spoon 2.5" exhaust.Dashed line is stock ( and stock Ecu ) with 2.5" exhaust

TDI north tuning fk7 spoon 2 .jpg
The reason this fk7 has gained horsepower is because tdi north fitted him with a ktuner running the dual 21psi starter. This explains the gain in power. After the first dyno run tdi north then tuned his ktuner to produce 250hp with 255lbft torque. Also spoon exhaust comes with a fronpipe and yes the cat is still stock.
 

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The reason this fk7 has gained horsepower is because tdi north fitted him with a ktuner running the dual 21psi starter. This explains the gain in power. After the first dyno run tdi north then tuned his ktuner to produce 250hp with 255lbft torque. Also spoon exhaust comes with a fronpipe and yes the cat is still stock.
Not quite …
Dashed is stock tune, dotted is stock boost level with optimized AFR & IGN and Solid is their custom 22psi map.
The stock tune produced 205hp but I don't think they have a base before changing the exhaust (front-pipe included)
 


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The reason this fk7 has gained horsepower is because tdi north fitted him with a ktuner running the dual 21psi starter. This explains the gain in power. After the first dyno run tdi north then tuned his ktuner to produce 250hp with 255lbft torque. Also spoon exhaust comes with a fronpipe and yes the cat is still stock.
If you read the description you'll see that TDI north says:
The dashed line ( the lowest in that graph) is stock map and the spoon exhaust was already fitted and that made 205 bhp.
Stock car has 182hp ...
The solid Line is the ktuner dual map.

Also Hollywoo0220 according to the compressor map of MHI itself the SI turbo only flows 300CFM Max .So 400cfm was way off. (0.14mÂł/s = 296cfm. )
 
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If you read the description you'll see that TDI north says:
The dashed line ( the lowest in that graph) is stock map and the spoon exhaust was already fitted and that made 205 bhp.
Stock car has 182hp ...
The solid Line is the ktuner dual map.

Also Hollywoo0220 according to the compressor map of MHI itself the SI turbo only flows 300CFM Max .So 400cfm was way off. (0.14mÂł/s = 296cfm. )
The MAX CFM is approx 400. What you are not accounting for is “turbo efficiency”.
If you perhaps read further, you would find this explained in 1(b).
 

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If you read the description you'll see that TDI north says:
The dashed line ( the lowest in that graph) is stock map and the spoon exhaust was already fitted and that made 205 bhp.
Stock car has 182hp ...
The solid Line is the ktuner dual map.

Also Hollywoo0220 according to the compressor map of MHI itself the SI turbo only flows 300CFM Max .So 400cfm was way off. (0.14mÂł/s = 296cfm. )
There has been no single FK7/FC1 that measured 182hp... most measure 175-182 at the HUBS, so 200'ish at the crank
 

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The MAX CFM is approx 400. What you are not accounting for is “turbo efficiency”.
If you perhaps read further, you would find this explained in 1(b).
Yes this was for the non si turbo, but the si turbo flows 300cfm @ aprox 65% efficiency. The non si turbo flows less then that ...
 

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There has been no single FK7/FC1 that measured 182hp... most measure 175-182 at the HUBS, so 200'ish at the crank
Could be Yes but i also seen a few around here that dyno stock 185-190hp at the crank.
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