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

Hollywoo0220

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For understanding purposes only:

FACTS

* Stock exhaust system is more than capable of supporting maxing out the turbo's capability. Pre-Cat is large, Mid-Pipe is 2.125" and exhaust is 2". Stock Turbo is the shortfall.
** The WG is is electronically controlled and the ECU uses "slope logic" to bring in spool. You can achieve increased spool with base tunes by adjusting the level of Ramp Rate already.

Previous testing of a downpipe system showed a reasonable bottom end to midrange improvement, but nowhere near the gains an ECU reprogram delivers. (et al Hondata)
***
(Corrected)

There are a few owners (as of this date) that have modified the stock turbo with the 27WON on a CVT.
As to the 'reliability' or 'daily driving' longevity it is uncertain. However, one owner has posted a 13.4s 1/4 mile @108mph on E85 blend. There is another owner who has opted for the Si turbo on a Non-Si (w/Full bolt-ons) and is just shy of that mark using Race Fuel.



THEORY

* The CVT has been tested for "capability"; however, no hard data has been reported as of this date.
WHAT is "Maximum" Torque? My estimation stands with a reputable individual that guesstimated approx 230-240lb/ft. Is that V6 levels of torque? The lower (under the threshold) the torque is kept in the gearing, the more reliable the CVT will be over time. The TSP tune reports a torque of 250lb ft; however, that number is limited under 4000RPM on CVT models and will arrive further to the right.
** It is important that when increasing torque, that the RPM band from which it is generated be moved further right (easier to achieve on the upgraded turbos / obtainable on stock with appropriate tuning).

*** The M/T models are about the same level of stock clutch safe operation; but closer to 240lb ft than higher.
**** There are numerous owners that have reported clutch slippage using higher than stock boost tunes.

1) Let's determine our Maximum Turbo Efficiency:


Maximum turbo CFM output = (3.14)(turbo compressor wheel size ÷ 2)2 / 3
So:
(3.14) x (39.1mm stock compressor wheel / 2) = (3.14) x (19.55)2
(3.14) x (19.55 x 19.55) = (3.14) x (382.20)
(3.14) x (382.20) = 1,200.11

Now, divide 1,200.11 by 3 = 400 (corrected)
Thus, the Maxium Turbo CFM output of the non-si turbo is 400 CFM.

a) A stock set-up is more than capable of handling the power that the turbo can produce effectively.
Using the highest Octane possible will get you to those numbers (i.e. Race Fuel, E-Blend, etc...)
b) **Max Flow DOES NOT equal "efficient" flow.
- Our stock turbo operates at 70-72% peak efficiency. That brings actually air flow down from 400 to around 280-290CFM (See Image #2).
c) From factory @5500rpm HP reaches it's peak; to get past that hump a more efficient turbo is required. This is the tranistion from boost is higher than exhaust back pressure TO exhaust pressure higher than boost. The power capability remains in the turbo's ability to push and pull.
d) Non-Si Turbo Exhaust Exducers are "11" Blades as opposed to "9" Blades for the CRV & Si models.
- The lesser blade # can exspel exhaust gases more efficiently; thus a bit higher RPM power.


2) Let's determine Spool time:

Spool time in seconds = turbo compressor wheel size2 / (exhaust PSI)(100)
So:
(39.1mm x 39.1mm) = 1529
(14.7psi barometric + 16.5psi Max Stock level x 100) = 3120
1529 / 3120 = .49
.49secs is your spool time


a) You can add your tuned PSI into the equation and see how your spool time is dropped at that level.

3) CONCLUSIONS:


Downpipes and aftermarket exhausts DO NOT add favorable power gains with the stock turbos. Aftermarket intakes are a "preference", not required.
--It is ideal to keep with the designed Bypass Valve and not migrate to a Vent to Atmosphere.

An Upgraded IC would be advantages in heavy duty "Street or Racing" applications that are utilizing higher PSI tunes, but not required for regular street driving.

Notes:
#1 In a FI vehicle, the air entering the combustion is after the IC. So, adding an aftermarket intake (claiming to provide more "cold air") is a moot subject. That colder air is being compressed and heated up by the compressor, then through the IC to be cooled - before being added to the combustion.
A more recent tuner on the market stated this in regard to the development of a Turbo Inlet Pipe (constructed of aluminum) and it's tendancy to transfer heat:

"Not like you would think, the air is always moving through it so it does not heat the air that much. Plus its pre-compressor so its important to have a good IC to help out."
A higher efficiency drop-in filter would function just the same (especially on a limited turbo). All that is needed is to meet the demand of air intake with velocity.
The optional MAF's available (Street/Race) are what provide for a bit more HP. You need a specfic tune to register the use of them; otherwise, your fuel trims will be off. That HP will only be available very high in the RPM and for a very short time.

#2 Upgrading the charge hoses (when increasing PSI) will decrease radiating heat, premature wear, collapsing, and provide a longer lifespan (dependability).

#3 By adjusting ignition, fueling and VTC, the Base Tunes (of both Hondata / KTuner) provide safe performance - even on a completely stock vehicle.

Things can be pushed a bit further with custom tunes and increased octane.

#4 The Stock spark plugs are the best option for ignition. Pre-gaps of .028-.030 for the turbo models are about standard. When increasing boost past stock (+/=4psi) it would be wise to gap down an addt'l .002 (on stock turbos). I will not cover extreme boost conditions, ask your tuner for recommendations.

#5 Monitor your Oil levels and increase your change schedules based on your driving styles (frequent short trips, stop & starts, increased spirited driving, etc.)
It is recommended to use oil brands that contain a higher volume of detergents & disperants to assist with cleaner piston burn and lowering the carbon signature (due to increased oil dilution issues).

#6 There has been a recent discovery about the differences between the stock air boxes of both Non-Si & Si models. Just understand, that they were designed for the differences in turbo specifications for each model (e.g. 9 blades breathes better than 11).

Just understand the limitations.


***For the Si and 6MT models, the sky is the limit with correct modification(s).

Now for a little entertainment:
It has become apparent that our vehicles may very well be equipped with TD025 turbos. However, given the boost levels of Base Tunes available from the two prominent tuners, we are more so likely on a TD03 turbo (as claimed by Honda). Let's look at the information available for both the TD025 and TD03 (See Image #1).

IMAGE #1

upload_2019-3-6_9-39-20.png


TD025:

The Max Pressure Ratio is 2.2.
So, if we were on a 21psi Tune then:


Pressure Ratio = Absolute Discharge Pressure / Absolute Turbo Inlet Pressure
(14.7psi + 21psi) / 14.7

35.7 / 14.7 = 2.42

The arguement here is:
How can our turbo achieve a Pressure Ratio of 2.42 if it is a TD025?

TD03:
The Max Pressure Ratio is 2.9
So, if we were on a 21psi Tune then the 2.42 Pressure Ratio falls within the capability of the turbo.
That is engineering logic.

***The contention is that our TD025's are a "HYBRID" that possess a higher PR than a standard TD025.
***Which I would have to agree with. As what was released by HONDA displays the Compressor Map of our 1.5L turbos. (See Image #2)


IMAGE #2

upload_2020-2-27_10-59-26.png


With a Pressure Ratio of 2.4 on a turbo with a ceiling of 2.9, you will be in the higher efficiency islands of the compressor map more sustainably; without maxing out the stock turbo's capability.

The turbo will be working harder to obtain a boost target. For example:
The MAP is registering 19psi but the compressor is operating at 21ps and your target is 21psi. That difference is "System Pressure Loss" and is a thermodynamic principle; better known as Bernoulli's principle. Which in simple terms means that when you draw air from outside, you are drawing air in at atmospheric pressure. However when it gets pulled through the filter and air tubing, the pressure actually drops BELOW atmospheric. So, your ECU then increases the compressor PSI to reach your target of 21psi - so, your turbo is actually in a higher PR than your target.

I would also like to point out that Honda (or any other manufacturer) are in fact providing you correct technical information as it pertains to boost pressure. Just understand that from this point forward, as you are reading the MAP level on your tuner or datalog - that your turbo is actually producing more PSI than that to achieve the target.

Hope that helps....

*Article Update as of 6APR20



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Myx

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@Hollywoo0220 Big thanks for this post.

I just happen to be looking for max torque numbers the CVT can hold and max horsepower the turbo can make to determine my full modification route. This post/thread is gold. Kudos!

And thanks for stating what I'm trying to do with my current setup. I actually posted a thread asking about pressure loses and you answered it. I am currently trying to reduce any pressure lose associated with everything from the air filter to the throttle body. I just purchased a manometer to check this (Never used one before) but I procrastinate.


Edit: Cubit Feet Per Minute to Grams Per Second (CFM to G/S Conversion).
 
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Hondanickx

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Where's the proof a stock exhaust isn't a restriction? I've seen several people going from stock 182hp to 200hp with just a 2.5" exhaust ,everything else stock.
 

Myx

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I've seen several people going from stock 182hp to 200hp with just a 2.5" exhaust ,everything else stock.

Where did you see this?
 
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charleswrivers

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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
20171229_104114.jpg
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.
 

Hondanickx

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Where did you see this?

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
 
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"*** Not one tuner or developer has tested an upgraded turbo on a CVT model (as of this date)."

I realize several months have passed but I believe a PRL customer has their big turbo kit on a 1.5 CVT car now.
 
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Hollywoo0220

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This 2.5” Exhaust talk is relative to the Si - that’s what I see.
Like the “Metric” reads:
You can gain the same power with the stock exhaust - it is not restrictive. The difference is “Tuning”, not just simply throwing on exhaust and getting power.
The Si & CR-V can expel a bit more exhaust than the non-Si variants. Neither model however, have restrictive exhausts.
 
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Hollywoo0220

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"*** Not one tuner or developer has tested an upgraded turbo on a CVT model (as of this date)."

I realize several months have passed but I believe a PRL customer has their big turbo kit on a 1.5 CVT car now.
Have not seen any reports of that matter.
 

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This 2.5” Exhaust talk is relative to the Si - that’s what I see.
Like the “Metric” reads:
You can gain the same power with the stock exhaust - it is not restrictive. The difference is “Tuning”, not just simply throwing on exhaust and getting power.
The Si & CR-V can expel a bit more exhaust than the non-Si variants. Neither model however, have restrictive exhausts.
You are blind , they are all Untuned , and all FK7's so where does this even come from....?:dunno:

However it could be that the restriction is from the downpipe/cat and that a bigger exhaust helps to extract more exhaust gasses and the gain is from that. All these dyno's are with a stock " restrictive " cat.The theory of what a certain size exhaust flows can't tell you if the whole exhaust system isn't restrictive somewhere.All oem honda exhausts are made tapered because exhaust gasses cool down the further away they go and they take up less space in the exhaust.To keep the exhaust pulses going at the same velocity the exhaust size gets smaller.
 
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You are blind , they are all Untuned , and all FK7's so where does this even come from....?:dunno:

However it could be that the restriction is from the downpipe/cat and that a bigger exhaust helps to extract more exhaust gasses and the gain is from that. All these dyno's are with a stock " restrictive " cat.The theory of what a certain size exhaust flows can't tell you if the whole exhaust system isn't restrictive somewhere.All oem honda exhausts are made tapered because exhaust gasses cool down the further away they go and they take up less space in the exhaust.To keep the exhaust pulses going at the same velocity the exhaust size gets smaller.
Let’s try this again.
Swapping the stock exhaust for a 2.5” is not going to net more power by itself.
Be mindful of what you read and question everything you only see.
You can achieve 280-290hp from a 2” exhaust, if you have a turbo that will get you there. Try maxing the turbo first before adding many another item.
 
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gtman

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Let’s try this again.
Swapping the stock exhaust for a 2.5” is not going to net more power by itself.
What he said.

No way just increasing exhaust piping a half inch and using aftermarket mufflers on an otherwise stock base Civic is legitimately adding 18 hp in and of itself.

If that was the case, 2.5" aftermarket exhausts would be selling like hotcakes.
 

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Let’s try this again.
Swapping the stock exhaust for a 2.5” is not going to net more power by itself.
Be mindful of what you read and question everything you only see.
You can achieve 280-290hp from a 2” exhaust, if you have a turbo that will get you there. Try maxing the turbo first before adding many another item.

That's theory of what a 2" pipe can flow max .You can never achieve that if the exhaust is 2" right after the downpipe (cat). .All of them who get 280-290hp enlarge the downpipe and/or front pipe .
 
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Myx

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This all is making for some interesting discussion. I'm only running a PRL Downpipe as my PRL front pipe was damaged from a bad install. The dyno chart above is interesting as well.

I'm still looking for the dyno post/link/thread that PRL stated (It was PRL If I remembered right) when they removed the piping from the front pipe, no horsepower was gained. This was why they never developed an exhaust for the Non-Si. Can't find it at the moment though. I purchased a 3" Injen despite that, that I had modified to be 3" from the front pipe back but I never ran a faster 1/4 mile time or trap speed with it. I didn't run a worse time, just not faster than my stock piping.
 

Hondanickx

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This all is making for some interesting discussion. I'm only running a PRL Downpipe as my PRL front pipe was damaged from a bad install. The dyno chart above is interesting as well.

I'm still looking for the dyno post/link/thread that PRL stated (It was PRL If I remembered right) when they removed the piping from the front pipe, no horsepower was gained. This was why they never developed an exhaust for the Non-Si. Can't find it at the moment though. I purchased a 3" Injen despite that, that I had modified to be 3" from the front pipe back but I never ran a faster 1/4 mile time or trap speed with it. I didn't run a worse time, just not faster than my stock piping.
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.
 
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