My Goal of 30mpg and 300hp

[Mikey B]

Why would california care if you were ELH?

 

And more confused that you'll somehow be able to go with an aftermarket DP but NOT ELH? headers and/or up are WAY more "hidden" than a DP.

 

Could also just go JDM twinscroll and it'll all look stock... you'll even get your bellmouth DP and be able to use it as is if you get a version 9 JDM STI DP.

 

Topfeed conversion (and deletes even) would be equally simple and easy to "hide".

 

 

Not alot of this makes sense. Do you really want input or do you just want to do what you said you wanted to do in your first post?

 

 

And forget all the engine mods, you don't need any of that for 300hp. 300hp is reliable and completely doable on a stock engine.

 

 

Understanding CA smog laws will really, really make your head hurt.

 

 

It has to pass a visual inspection of all emissions related parts, everything pre cat and post maf have to be %100 OE visually.

 

then they plug in to see if you have any pending or set codes with complete monitors. if its clear, your done. no tail pipe emissions. it could be full VW pouring black smoke out the tail and they wouldnt care.

 

But thats beside the point.

 

I just dont want to swap header and uppipe come smog time.

 

i may even just leave the stock DP just for sake of the damn "random inspections"

 

and im not ignoring posts just to do what i wanted in the first post.

 

My first post is what i plan on doing and i wanted to hear everyones opinion on what i could do to improve on that idea. Just because I dont want to take the path of what you recommend doesnt mean im ignoring it. Im taking in information and opinions and experiences to see whats going to work best for me.

 

Thank you for the help

[mondtster]

Understanding CA smog laws will really, really make your head hurt.

 

 

It has to pass a visual inspection of all emissions related parts, everything pre cat and post maf have to be %100 OE visually.

 

I wondered if smog laws and emissions inspections would need to be considered. This is even more reason to abstain from major configuration changes and stick to ECU program changes (reversible at smog time) and drag reduction.

 

Presumably the inspector will check for the up pipe catalyst in addition to the downpipe ones?

[Nightmaresmk]

This what i have for visual inspection.

http://www.daddysscp.com/product_p/mdmv21p.htm

If you get an JDM ELH you will have a stock look. if you get the the stock Twinscroll JDM Header, up and stock down combine with a 1.5xtr TS turbo. efficient 300whp with response and is completely stock.

[covertrussian]

My suggestions would be Equal length header. Get the header/up/turbo hotside and downpipe ceramic coated. get a grimmspeed TMIC. maddad or nameless catted downpipe. A blouch 18gxt-r, tomioka racing billet 18g(i have this one) or similarly sized as the trans sucks a lot of power.

I get 25mpg with my setup but i have 6spd gearing on my side.

Get the cylinder bores WPC treated if you can afford it. Your basically trying to make the engine as efficient as possible.

 

Not trying to dog on you, but 25mpg is really low, especially after couple k in mods. I've been toying the idea of equal length headers myself, or more efficient unequal length ones, but I just can't justify the cost of with possibly negligible mpg gains.

 

All those things should really increase gas mileage, WPC shouldn't hurt it either. The only thing I can think of is the tune on your side.

 

Slightly off topic but I watched a video yesterday of a guy who achieved around 40mpg while cruising at 55mph with his 2015 wrx! Unbelievable. At 70-75mph, he consistently achieves 33mpg. And he is not trying to hypermile or anything. Just use the cruise control. He is stock btw.

 

With direct injection, 6 speed, Dual AVCS, I can't say I'm surprised. I bet our EJ's could achive 35mpg stock going 55mph too, but I can't even find a road to do that test on where I live. If I got below 70mph I'll get run off the road or pulled over here...

 

I'm actually surprised that the new WRX's are rated at only 28mpg, but from the sounds of it Subaru purposefully under-rated them otherwise EPA really gets in your business when you say a car gets over 30mpg.

 

One thing nobody has mentioned is tires and alignment. I was easily pulling 29-31 mpg until I bought a new set of tires for it. That immediately dropped the mileage 2 mpg and I've never been able to get it back no matter what I do with it. I won't be getting another set of these tires...

 

Different tread patterns have different rolling resistance, rubber compound does too. This is why TireRack started testing MPG's on the different tires they test, which is awesome of them.

 

Right now I'm running Cooper RS3-A's that are wider then oem (225's vs 215) and they still get awesome gas mileage.

 

 

I'd focus more on what you can do aerodynamically and reducing losses within the driveline and less on the engine.

 

You want efficiency and are really planning on overhauling the motor? Put higher compression pistons in it. Off boost efficiency should be improved. Or just put an EJ20Y in it and call it a day.

 

Compression is where it's at, higher compression means more efficiency in power and gas mileage. But with higher compression you hit boost limits much faster. My other car is a 9.5:1 CR motor that I turbo charged, makes more power at less PSI then the legacy and gets much better gas mileage, but I wouldn't run more then 16psi on it daily on a VF40 sized turbo.

 

There is no way, no how that you're going to get 300 horsepower and 30 mpg at concurrently. The same engine may be able to do both however, and what you need to do to get mileage is to reduce the horsepower required to move the car or keep it moving. That should also help make that 300 horsepower more fun when you decide to use it.

 

Why is it no way possible to get both 300whp and 30mpg? With fuel injection, unlike carburated cars, 3d fuel and timing maps enable you to do that fairly easily. Granted if you drop in even lower compression pistons then sure that will hurt you, but as we've seen stock compression is more then able to get 300whp and 30mpg separately. It's just no one really cares about modding for gas mileage, so they don't care.

[mondtster]

Why is it no way possible to get both 300whp and 30mpg? With fuel injection, unlike carburated cars, 3d fuel and timing maps enable you to do that fairly easily. Granted if you drop in even lower compression pistons then sure that will hurt you, but as we've seen stock compression is more then able to get 300whp and 30mpg separately. It's just no one really cares about modding for gas mileage, so they don't care.

 

Reread my post. I said you could not do 300 horsepower and 30 mpg concurrently. A 300 horsepower engine running at rated power is going to consume around 30 gallons/hour, give or take a couple of gallons. At the power settings needed to maintain highway speeds (low) you ought to be able to net 30 mpg. But the engine will not be making 300 horsepower at that point.

 

This is the reason I suggested targeting drivetrain efficiency and aerodynamics rather than obsessing over an engine. Any excess drag in the drivetrain or aerodynamics area is going to cost you because it requires more power to move the car, and you're at cruise power settings way more often than you are at full power.

 

Maybe I'm weird, but I tune/modify stuff with efficiency in mind. I like power too, but will sacrifice a bit of peak power for drivability and a more efficient engine and vehicle.

[covertrussian]

Reread my post. I said you could not do 300 horsepower and 30 mpg concurrently. A 300 horsepower engine running at rated power is going to consume around 30 gallons/hour, give or take a couple of gallons. At the power settings needed to maintain highway speeds (low) you ought to be able to net 30 mpg. But the engine will not be making 300 horsepower at that point.

 

I wasn't sure what point you were trying to stick to since it was fairly contradicting, but sarcasm is hard to convey over text without smileys . Sure you can't get 30mpg instantaneous and 300hp as your flooring, but no one, outside of a race track, drives full throttle everywhere.

 

This is the reason I suggested targeting drivetrain efficiency and aerodynamics rather than obsessing over an engine. Any excess drag in the drivetrain or aerodynamics area is going to cost you because it requires more power to move the car, and you're at cruise power settings way more often than you are at full power.

 

Maybe I'm weird, but I tune/modify stuff with efficiency in mind. I like power too, but will sacrifice a bit of peak power for drivability and a more efficient engine and vehicle.

 

While I agree with you to a point, engine has far more fixable inefficiencies then a drivetrain does. With drivetrain most fixable inefficiencies are related to maintenance (like old fluids, sticking brakes, slipping clutch). To gain more efficiency out of drive train you would have to do lighter 15" wheels (which wont clear the brakes), Smaller brakes with lighter rotors would help too, from there lighter flywheel, driveshaft, and axles is about the only things left. Lighter flywheel is a bit of a toss, on my other car I didn't gain anything noticeable, especially not highway.

 

For my legacy most of the gains came from the tune alone, only reason I went with Stage 2 downpipe is because I destroyed my stock one by running a dear over. Highway Gas mileage stayed the same going from stock to stage 2 though. With new downpipe I did learn a few more tricks with the tune which is what finally got me to 31mpg range.

 

Now I'm back to 30mpg because I disabled D learning by setting the D learning from 40 to 80, which reduced the resolution amount and gas mileage. But it prevents me from leaning out in open loop, so engine reliability is more important for me.

[covertrussian]

A week after I got the car, I drove it from Schenectady to Rochester, then to Toronto, and back (pretty much I-90 the whole way). On the way back I managed to average 29mpg, stock tune going around 70mph.

 

The hardest thing is keeping it out of boost due to a combination of both the VF40 being a tiny turbo that spools like yesterday, and self-control. The car would probably be easier to drive efficiently with a larger turbo, actually. I was catching it making a few PSI going up hills, watching the instant MPG readout (didn't have my AP yet) and lifting when it would start to spool up/tank the fuel economy. Just letting the cruise control do its thing often resulted in unnecessary boost and the accompanying hit to fuel economy.

 

 

29mpg on a stock car is actually really impressive, unless it was all downhill?

 

Anyway, I used to think the same about the VF40 that it was hitting boost too easily on the highway, pressing the cruise control up would lunge you back into the seat too much. The main cause of this is actually the ECU's doing with Wastegate Duty Cycle tables.

 

Here's why: without a boost controller, wastegate actuators will start opening up as you start building boost, wastegate gates are not on-off valves basically. Since the gate is cracked open, wont be building boost as quickly, aka turbo lag. An Electronic Boost Controller (stock on our cars) will start bleeding off the amount of pressure the wastegate actuator sees, keeping the gate closed longer, thus reducing turbo lag.

 

One way to fix this is to tell the ECU not to build boost under certain throttle/rpm conditions. This is what I did with my tune and the car is much tamer on the highway now.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/Boost/05LGT_STG213psi_Boost_v1.0.png~original

[MTBwrench]

29mpg on a stock car is actually really impressive, unless it was all downhill?

 

Anyway, I used to think the same about the VF40 that it was hitting boost too easily on the highway, pressing the cruise control up would lunge you back into the seat too much. The main cause of this is actually the ECU's doing with Wastegate Duty Cycle tables.

 

Here's why: without a boost controller, wastegate actuators will start opening up as you start building boost, wastegate gates are not on-off valves basically. Since the gate is cracked open, wont be building boost as quickly, aka turbo lag. An Electronic Boost Controller (stock on our cars) will start bleeding off the amount of pressure the wastegate actuator sees, keeping the gate closed longer, thus reducing turbo lag.

 

One way to fix this is to tell the ECU not to build boost under certain throttle/rpm conditions. This is what I did with my tune and the car is much tamer on the highway now.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/Boost/05LGT_STG213psi_Boost_v1.0.png~original

 

Not trying to derail the thread for my own purposes here, but very interesting you said that about CC acceleration. My biggest gripe has always been exactly that. With my new tune, I'll hit 14psi easy, way too much acceleration. Maybe next tune I'll ask for a modified WGDC table.

[Phate]

29mpg on a stock car is actually really impressive, unless it was all downhill?

 

Anyway, I used to think the same about the VF40 that it was hitting boost too easily on the highway, pressing the cruise control up would lunge you back into the seat too much. The main cause of this is actually the ECU's doing with Wastegate Duty Cycle tables.

 

Here's why: without a boost controller, wastegate actuators will start opening up as you start building boost, wastegate gates are not on-off valves basically. Since the gate is cracked open, wont be building boost as quickly, aka turbo lag. An Electronic Boost Controller (stock on our cars) will start bleeding off the amount of pressure the wastegate actuator sees, keeping the gate closed longer, thus reducing turbo lag.

 

One way to fix this is to tell the ECU not to build boost under certain throttle/rpm conditions. This is what I did with my tune and the car is much tamer on the highway now.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/Boost/05LGT_STG213psi_Boost_v1.0.png~original

 

Rochester to Schenectady is, on the whole, slightly uphill in terms of overall elevation change. Too many hills in between to really count it as such, though. On my most recent long trip, I managed just over 26 average, which includes getting ~28 on I87 heading to Montreal and back, along with a good chunk of probably 13mpg city driving that drove the average down a lot. The biggest gains that I see on the highway seem to come from carefully watching manifold pressure on the accessport, and lifting off the throttle when engine load starts to increase. You can feel the car start to load up and see the instant MPG tank. Lift and lightly reapply throttle and the car doesn't lost speed but cruises along at lighter load/more vacuum.

 

I was actually thinking about how to adjust the wastegate duty cycle tables to accomplish what you're showing. If I really want to hit boost, I can just push the gas pedal farther. I'll have to take some datalogs at cruise to see what things are doing, but I don't know how well the chinacharger is going to behave with that. It took a bit of fiddling to make it behave the way it's supposed to out of the box.

 

I might just have to get my hands on a stock VF40 wastegate actuator.

 

I was mostly bummed that I couldn't hit the 36-37 mpg that my accord got on the same drive.

[covertrussian]

I can't help you with Cobb, since I never laid hands on it, but table names are usually somewhat similar.

 

Keep in mind the stock map sensor is very inaccurate in vacuum, it reads -10 psi (really it's positive in/hg but for simplicity sake I'll call it psi), while a real boost gauge will read -23psi idling and is usually around -15psi cruising. Stock map sensor only starts reading correctly as you get close to 0psi, so just use it to confirm that you are below 0psi and you should be fine.

 

Why bother with the VF40 actuator? Different turbo has different flow rates and those table values will look very differently then what mine do. Just keep it similar, force 0 WGDC and -10psi in most cruising points and you should be fine.

 

 

I'm actually surprised that you would expect 36mpg out of an AWD low compression turbo car. It's a battle for me getting to 30mpg (in colder temps, warmer temps make it easier). My personal goal is 35mpg with a bigger turbo, but realistically probably wont happen with 8.2:1 pistons.

[Phate]

Why bother with the VF40 actuator? Different turbo has different flow rates and those table values will look very differently then what mine do. Just keep it similar, force 0 WGDC and -10psi in most cruising points and you should be fine.

 

I'm actually surprised that you would expect 36mpg out of an AWD low compression turbo car. It's a battle for me getting to 30mpg (in colder temps, warmer temps make it easier). My personal goal is 35mpg with a bigger turbo, but realistically probably wont happen with 8.2:1 pistons.

 

The VF40 actuator would be to ensure things are behaving exactly as they should, rather than being tuned to behave as they are now.

 

I wasn't expecting 36 out of it (although my mom's 2012 2.5i cvt does 33, likely because of some sort of part time awd), that's just what I was used to from the last car I took on a long trip. I'm pretty okay with 28 on the highway.

[covertrussian]

The VF40 actuator would be to ensure things are behaving exactly as they should, rather than being tuned to behave as they are now.

 

You can try, but the only thing that actuator does is determine the base boost pressure, which is around 6psi. Aftermarket ones will usually have higher base pressure, which does mean different WGDC tables.

 

I wasn't expecting 36 out of it (although my mom's 2012 2.5i cvt does 33, likely because of some sort of part time awd), that's just what I was used to from the last car I took on a long trip. I'm pretty okay with 28 on the highway.

 

Your mom's 2.5i is full time AWD too, there are a ton of reasons for why it gets better gas mileage. For one it's a completely different motor, but here are some more details...

1. CVT - CVT is more efficient then automatics and manuals. This alone accounts for 2-3mpg (My 6 speed 2012 Outback is rated at 27mpg hwy, while CVT is rated for 29mpg)
   
2. Higher static compression: 10:1 vs 8.2:1. Higher compression means more efficiency off boost
   
3. Cam Design: SOHC vs DOHC, SOHC boxers have two rotational masses, while DOHC's will have four rotational masses. Along with two extra cam sprocket weights.
   
4. AVLS - Basically the motor has variable valve lift on one of the intake valves that introduces a swirl in the airflow which helps atomize the fuel
   
5. No LSD's to go bad, 2010+ have open differentials and use VDC instead.
   
6. Tunes will be vastly different
   

 

As you can see there is always more to it and you can't just say well this car gets better gas mileage thus mine should automatically be better too.

 

I personally have been having issues getting above 28mpg lately with winter gas and colder weather (below 60F), while the same car/tune will do 30-31mpg when it's 70*F out.

[heiche]

Keep in mind the stock map sensor is very inaccurate in vacuum, it reads -10 psi (really it's positive in/hg but for simplicity sake I'll call it psi), while a real boost gauge will read -23psi idling and is usually around -15psi cruising. Stock map sensor only starts reading correctly as you get close to 0psi, so just use it to confirm that you are below 0psi and you should be fine.

 

Just fyi - I think the stock map sensor is actually quite accurate, but it reports PSI whether negative or positive. A typical boost gauge is really 2 gauges in 1: above atmospheric it reports PSI boost, and below atmospheric it reports inHg "vacuum".

 

To convert, 1 psi = 2.036 inHg

 

So at idle, a boost gauge might say -23 inHg, but your ECU will report -11.3 psi

[covertrussian]

Just fyi - I think the stock map sensor is actually quite accurate, but it reports PSI whether negative or positive. A typical boost gauge is really 2 gauges in 1: above atmospheric it reports PSI boost, and below atmospheric it reports inHg "vacuum".

 

To convert, 1 psi = 2.036 inHg

 

So at idle, a boost gauge might say -23 inHg, but your ECU will report -11.3 psi

 

I cannot like this post enough, this is amazing and eliminates the need for an electronic boost gauge to manually feed into RomRaider! I wonder if I can write a RomRaider gauge that will automatically convert the numbers for me .

 

I'm used to my GM 3.5 Bar with NismoTronic in my Nissan, the software I use is smart enough to do these conversions and shows me vacuum correctly

[cBax]

I had my evo set up to log kPA so it was super easy to correlate to the load columns as well as helped get VE tuning dialed in for Speed Density. If the RR logger is anything like EvoScan, I'm sure it wont be hard at all to display in PSI, BAR, kPA, etc.

 

Ive had my car running for an entire weekend since I purchased it (rod bearing, click link in sig) and barely had enough time that weekend to pull the rom and check things out. But I did not know the sensor read + pressure. How big is the sensor? 2 bar (14.5psig)? 3 bar (29psig)?

[covertrussian]

I might have to switch to kPA, I think Romraider lets display that. My mind is just so programmed with in/hg and psi that it's hard to correlate KPA to a certain psi.

 

Sounds like OEM MAP sensor is good for around 23psig. So around 2.5bar.

[Phate]

I cannot like this post enough, this is amazing and eliminates the need for an electronic boost gauge to manually feed into RomRaider! I wonder if I can write a RomRaider gauge that will automatically convert the numbers for me .

 

I'm used to my GM 3.5 Bar with NismoTronic in my Nissan, the software I use is smart enough to do these conversions and shows me vacuum correctly

 

Yup, AP reports boost and negative boost in PSI, rather than boost in PSI/vac in in/hg. -10psi is about right for idle.

 

 

I wonder if anyone on ecomodder has messed around with a 4th gen legacy. People there get crazy with aero to make their cars slippery (and sometimes goofy looking) as hell.

 

There was a guy on there that modified like 6 load cells on his boosted del sol to pretty much lean the crap out of the tune at the specific cruising rpm. In addition to some aero mods, he pulled something like 72mpg out of a turbocharged D16 that made over 300whp. Something similar should be possible with the LGT, but engines for these are a bit more expensive (and seeming less tolerant of pinging than the near-indestructable SOHC honda engines).

[FLlegacy]

My 5th gen can do 30mpg all day long on the highway!

[covertrussian]

I'm usually not a fan of trick modding or trick driving for improving gas mileage. I want to be able to get good gas mileage without pulse gliding and without using cardboard boxes

 

My 5th gen can do 30mpg all day long on the highway!

 

That's pretty awesome, 6 speed is probably helping (though it doesn't seem like 4th gen spec b's really get into 30's either). So maybe new manifold, turbo and tune?

[Nightmaresmk]

Mine has a 6spd with outback sized tires and i don't even hit 30mpg. Mind u i am over 335/377 to the wheels. Can i hyper mile it and get 30 probably but whats the point of the power at that point.

[covertrussian]

Just curious, what kind of size tires are those? Generally speaking going bigger tires can help since you reduce rev's per mile, but to a point since you are moving heavy weight out.

[covertrussian]

Just a quick update about the Romraider gauge.

 

I copied the logger file and added another unit conversion to E113 - Manifold Relative Pressure (4-byte). You can see the full thread here.

 

This basically says, if X is less then 0 use vacuum (in/Hg) calculation, else use boost (PSI) calculation.

<conversion units="psi/inHg relative" storagetype="float" expr="if(x*0.01933677<0,x*0.03937,x*0.01933677)" format="0.00" gauge_min="-40" gauge_max="60" gauge_step="10" />

 

 

Here's the log of the gauge, you can see it matching to the in/Hg of another gauge in vacuum and then matching boost of a third gauge. Since all 3 gauges use different calculation methods the values will slightly vary between them.

Manifold Relative Pressure (psi)	Manifold Relative Pressure (4-byte)* (psi/inHg relative)	Manifold Relative Pressure (Corrected) (inHg)
-7.25	-14.84	-15.06
-7.4	-15.02	-15.06
-7.4	-15.12	-15.36
-7.55	-15.56	-15.36
-8.42	-17.39	-16.83
-9.14	-18.87	-18.6
-9.72	-19.91	-19.79
-10.01	-20.45	-20.38
-10.16	-20.7	-20.67
-10.16	-20.38	-20.97
-6.67	-12.87	-14.47
-5.66	-11.34	-11.81
-5.8	-12.25	-11.81
-6.67	-13.63	-13.58
-6.82	-13.76	-13.88
-6.82	-13.86	-13.88
-6.82	-13.86	-13.88
-6.82	-13.83	-13.88
-6.82	-13.81	-13.88
-6.67	-13.63	-13.88
-5.8	-10.89	-12.11
-2.47	-3.08	-7.09
0.29	0.49	0.3
1.16	1.31	2.07
2.03	2.15	3.84
2.9	3.12	5.32
3.92	4.01	7.68
4.93	5.14	9.74
5.95	6.3	12.4
7.25	7.46	14.76
8.27	8.61	17.13
9.43	9.52	19.19
10.16	10.18	20.67
10.45	10.64	21.56
10.88	10.84	22.15
10.88	10.89	22.44
11.03	11.06	22.74
11.03	11.08	22.74
11.03	10.85	22.74
4.5	2.52	12.11
-2.76	-7.62	-4.13
-6.09	-13.42	-12.11
-8.13	-17.08	-16.24
-9.43	-19.45	-18.6
-10.01	-20.48	-20.38
-10.3	-21.08	-20.67
-10.45	-21.25	-21.26
-10.45	-21.25	-21.26
-10.45	-21.2	-20.97
-10.45	-21.15	-20.97
-10.45	-21.14	-20.97
-10.45	-21.14	-20.97
-10.45	-21.22	-20.97
-10.45	-21.24	-21.26
-10.45	-21.24	-21.26
-10.45	-21.24	-21.26
-10.45	-21.24	-21.26
-10.45	-21.22	-21.26
-10.45	-21.19	-20.97
-10.45	-21.15	-20.97
-10.45	-21.12	-20.97
-10.3	-21.07	-20.97
-10.3	-21.05	-20.97
-10.3	-20.95	-20.97
-10.3	-20.8	-20.67
-10.01	-20.51	-20.38
-10.01	-20.17	-20.08
-9.72	-19.8	-19.79
-9.72	-19.48	-19.49
-9.43	-19.18	-19.19
-9.29	-18.86	-18.9
-9.29	-18.77	-18.6
-9.14	-18.72	-18.6
-9.14	-18.69	-18.6
-9.14	-18.77	-18.6
-9.29	-18.79	-18.6
-9.29	-18.84	-18.6
-9.29	-18.94	-18.6
-9.29	-19.09	-18.9
-9.43	-19.17	-19.19
-9.43	-19.19	-19.19
-9.43	-19.19	-19.19
-9.43	-19.19	-19.19
-9.43	-19.19	-19.19
-9.43	-19.19	-19.19
-9.43	-19.19	-19.19
-9.43	-19.19	-19.19
-9.43	-19.14	-19.19
-9.43	-19.14	-19.19
-9.43	-19.14	-19.19
-9.43	-19.12	-19.19
-9.43	-19.1	-19.19