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Discussion Starter · #1 · (Edited)
I picked up this Insight this year during pandemic while unemployed and put together a car that is my "Cake and Eat It Too" commuter. Goal was to build a commuting supercar that get great MPGs for its speed. MPG wise I'm looking to average in the 50s for mile 50 mile daily commute. Here is my parts list.
Engine is K20, a2 block, a3 head which gives 11.5:1 CR
Turbocharger is Garrett gt2554r which maxes out at 240hp, boost is @6psi
2.25" exhaust including 2 Manaflow muflers, car is quiet.
Kpro V4, AEM wideband for closed loop
Intercooler is Frozenboost air to water kit
transmission 1-5 is Accord set and FD is 4.1 from CRV diesel, LSD from civic Si
Tires are Toyo Extensa 185/55/16
Pioneer deck, 1400 watts of JL amps, 2 JL 10w3 and front and back Polk Audio
Cluster is from 93 Del Sol

Initial dyno runs are 200whp @ 6500 and 195# @ 2500, car feels like a V8

I have not been able to get a good MPG number yet due to a few gremlins I've run into including few that I want to run by this forum, but I figured before I get into all that I'd introduce the car to the group
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Discussion Starter · #2 ·
The first thing I can't explain is every time I unplug the battery the passenger side window stops operating, sometimes for a few hours, sometimes a few days......

Next, My brights are permanently on when lights are on, Im about to start digging on this since it is a new thing but I thought I would check here first

The other issue I have is directed to anyone who know Scangauge2...... Mine doesn't work in the insight.... Considering I do have a K swap and did have to run a data wire to the OBD2 port to pass emissions, maybe there is a way to either reprogram the Scangauge or rewire the port wiring as so long as I can still pass emissions.
 

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Really like the car. I prefer a digital dash though. Keeps the character of the car. What hubs are you using for the 5-lug swap? Does it have bigger brakes too?
 

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Really nice build. I don't think your MPG goal is going to be met. I think you'll be lucky to be in the mid30s. That power is not free after all. I imagine it's going to be a hoot to drive.
 

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Really nice build. I don't think your MPG goal is going to be met. I think you'll be lucky to be in the mid30s. That power is not free after all. I imagine it's going to be a hoot to drive.
It's definitely possible to get near that number with a decent lean burn tune. I have seen a couple K-Swaps here on these forums where people are getting 42-55mpg without too much of an issue.
 

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It's definitely possible to get near that number with a decent lean burn tune. I have seen a couple K-Swaps here on these forums where people are getting 42-55mpg without too much of an issue.
I'm a shade tree mechanic on a good day so take what I'm about to write with a grain of salt; I thought it was not "good" for an engine to run lean. Our Insights were made to so they are the exception. Swapping a K-series engine (a turbo charged one at that) and making it run lean to achieve better MPG seems like a bad idea to me. If you want power and speed then throw a turbo 2L engine in and have fun with it. I'm kinda old (53) and grew up with the expression "you can't have your cake and eat it too". Seems appropriate in this case.
 

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I'm a shade tree mechanic on a good day so take what I'm about to write with a grain of salt; I thought it was not "good" for an engine to run lean. Our Insights were made to so they are the exception. Swapping a K-series engine (a turbo charged one at that) and making it run lean to achieve better MPG seems like a bad idea to me. If you want power and speed then throw a turbo 2L engine in and have fun with it. I'm kinda old (53) and grew up with the expression "you can't have your cake and eat it too". Seems appropriate in this case.
It's the high compression that makes it possible. As long as you keep learn burn to low in the load range, and a little bit of extra fuel on tip in, you shouldn't have any issues.

[Edit]: Now that I think about it, I don't think it's the CR, the CR just helps. My Volvo, which pushes 20psi at the top end, has a 'lean cruise' tune where it sits around 15.5-16.1 at cruise. Not to mention my CR is only 9.0:1 so, yea.
 

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It's the high compression that makes it possible. As long as you keep learn burn to low in the load range, and a little bit of extra fuel on tip in, you shouldn't have any issues.

[Edit]: Now that I think about it, I don't think it's the CR, the CR just helps. My Volvo, which pushes 20psi at the top end, has a 'lean cruise' tune where it sits around 15.5-16.1 at cruise. Not to mention my CR is only 9.0:1 so, yea.
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I'm not being sarcastic here but you're way smarter than I am with regard to this stuff. I always thought turbo engines needed to run a lower CR. What you guys are doing is way above my pay grade and I'm speaking from a place where I'd probably blow up my engine trying to get extra MPG. I can adjust my valves, clean an EGR plate, do brakes and an oil change.....messing with an ECU tune and blammo.....I've got a paperweight for a car. Ha.
 

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I'm not being sarcastic here but you're way smarter than I am with regard to this stuff. I always thought turbo engines needed to run a lower CR. What you guys are doing is way above my pay grade and I'm speaking from a place where I'd probably blow up my engine trying to get extra MPG. I can adjust my valves, clean an EGR plate, do brakes and an oil change.....messing with an ECU tune and blammo.....I've got a paperweight for a car. Ha.
You do generally want a lower CR for boost. However if your goal is to run low boost (both for longevity and fuel efficiency) then it's great to get the little bit of extra power from higher CR, since you aren't going to be going into boost levels that would conflict with the CR. There is also static CR (which is what most people know) and dynamic CR, but that's a story for another time.
 

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Here is a little info to really get you to thinking:
 

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GT2554R is a horrible match for your car. Look at the compressor map, even at 6psi your engine output is almost outside the turbo's efficient range. You can gain more power and efficient by going with a bigger turbo.

Your transmission gearing is not going to get your MPG you're looking for.
Your big wheels and tires is going to hurt MPG.
Having easily accessible power is going to hurt your MPG as you'll be tempted to step on it.
 

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Discussion Starter · #13 · (Edited)
GT2554R is a horrible match for your car. Look at the compressor map, even at 6psi your engine output is almost outside the turbo's efficient range. You can gain more power and efficient by going with a bigger turbo.

Your transmission gearing is not going to get your MPG you're looking for.
Your big wheels and tires is going to hurt MPG.
Having easily accessible power is going to hurt your MPG as you'll be tempted to step on it.
"Even at 6psi" you assume I want more and if it's "almost" out of range that would mean its still within range? You assume I'm looking for more power than I already have and you assume my gearing was chosen for MPG. The engine builder who specified the turbo and engine parts has the cred so I chose his opinion over yours. Easy access to the power is the point as well, this wasn't built only to get good mileage but to do so if I choose
 

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Really nice build. I don't think your MPG goal is going to be met. I think you'll be lucky to be in the mid30s. That power is not free after all. I imagine it's going to be a hoot to drive.
I averaged 57mpg on my way home from work today with a ~230hp K24. It was below freezing outside.
 

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Discussion Starter · #15 ·
Really nice build. I don't think your MPG goal is going to be met. I think you'll be lucky to be in the mid30s. That power is not free after all. I imagine it's going to be a hoot to drive.
If I use the turbo/ all the power all the time then yes, mid 30s, the idea is If I can hypermile the whole way which means no boost at all then I can get great hwy mpg, does that mean I will average that for the year, probably not but we're gonna find out, Scangauge 2 is all but working and probably a good month away from actual data logging..... Still trying to figure out some electrical issues.

I did take it on one 150 mile interstate trip (Vegas to Sima Rd the long way), averaged 77mph, top speed 124, MPG was 35, this was done with GPS app and bookended with fill ups.
 

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BongoBennie, you probably know this but there is FB group called K swapped Insights. I have found it very informative. I'm sure the K can cruise 16.5 afr but datalog with percentage of throttle opening to find if a different afr will lead to a smaller TB opening which indicates more efficiency, all things being equal.
 

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Discussion Starter · #17 ·
BongoBennie, you probably know this but there is FB group called K swapped Insights. I have found it very informative. I'm sure the K can cruise 16.5 afr but datalog with percentage of throttle opening to find if a different afr will lead to a smaller TB opening which indicates more efficiency, all things being equal.
I love that group, best FB group for sure.... I actually have 2 Insights, the other is an L15 A/T (2008 Honda Fit Sport 5sp A/T paddle shift) and have been it the group since then, If you count the red one I parted out, this is my third Insight..... If this car goes as planned, it will be short lived in its current form, 2 years max.
 

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Here is a little info to really get you to thinking:
Interesting article. It seems to lean toward American iron. There are a lot of head designs that are less det challenged. One of the keys to choosing a compression ratio is the ecu you have avaliable to control detonation. Retarding timing and air fuel ratios are key. Another is the octane you have avaliable, are you running 91, 93, E85? With current technology 10.5:1 is increasingly more common in 4V head designs allowing boost levels that were impossible 10 years ago for the average gearhead.
 

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Discussion Starter · #19 ·
Interesting article. It seems to lean toward American iron. There are a lot of head designs that are less det challenged. One of the keys to choosing a compression ratio is the ecu you have avaliable to control detonation. Retarding timing and air fuel ratios are key. Another is the octane you have avaliable, are you running 91, 93, E85? With current technology 10.5:1 is increasingly more common in 4V head designs allowing boost levels that were impossible 10 years ago for the average gearhead.
Several things... friends of mine have built the crap out of these engines and run 12.5:1 on pump gas, the engine was purpose built using all (mostly) Honda parts. The K20a3 head has more quench and on the side as well to promote swirl for economy, not power...... which is exactly why posting about anything a3 related on race/boost/swap related groups draws nothing but hate.... opposite of this group where I get hated for the "bad mileage". It's hard to brag about a boosted K that puts 200 to the wheels..... this car is basic and fun, not even a boost gauge. right now it has a very basic tune, it also has an AEM wideband wired in with a fancy bosch sensor wired in so I can mess with the lean burn but under full power it pulls hard anywhere in the powerband in an instant, wastegate is set at 6psi and there is no knock on 91.

Right now I'm working on the cluster which is a challenge to say the least, those $700 S2K units are looking nice as well as AEM maybe. I'm debating on a few things right now with the dash.
 

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Discussion Starter · #20 ·
Update, finally run 3 tanks through the car commuting.... gearing is right on, when driving aggressive this thing is an absolute blast however the tuning was basically full throttle pulls ..... driving it in traffic is a bit herky jerky and Im also averaging 33mpg which is meh......... so I sent my money to Evans Tuning which many consider one of the best in the business and we will be doing his very popular E-tuning service. I hope to have my first upload in the morning and get the car running like a Honda. Also scheduled my tint and alarm. Exciting!!
 
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