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Discussion Starter #1
Finally got my transmission fully sorted, and thought I'd share my fuel economy numbers.

Details on my car can be found in these two threads:



The short of it : K24 (TSX) engine with some modifications, TSX 6 speed transmission with some modifications.

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To get my current gearing, I ordered a custom 3.4 final drive and the 6th gear from a 2012 Civic Si, inspired by Mike Lewin's setup. Resulting 6th gear is ~2% taller than the Insight's stock 5th gear. I also upsized the tires by ~1.5%, resulting in a cruising RPM of just over 2100rpm @ 65mph.

Today, outside temperature was ~35F, sunny. Roads were mostly dry, some damp spots from melting snow. A light breeze, mostly a crosswind. Car was fully warmed up. It was difficult to tell if I was on entirely level ground at times, but these numbers should be accurate to within 2-3mpg.

40mph - 55mpg
50mph - 52mpg
65mph - 47.5mpg
75mph - 43.5mpg




With the stock engine and in good weather I was able to get nearly twice the fuel economy at 50mph. However during similar weather I'd typically be looking at 65-80mpg at 50mph. I'll be interested to see how it improves in summer, but for now it's looking like I'm using around 1.5x the fuel in similar conditions. Subjectively? Worth it for 3.5x the horsepower.

 

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You have a great car.
You've been really good at posting details of your progress along the way.
There have been a lot of things that have interested me in your posts across many forums.
Thanks for all your posts.
I'm curious about your fuel mileage. In another post either here or elsewhere, you mentioned you'd like to achieve 60+ MPG. (And I think I recall you getting nearly 65 not long ago.) Do you suppose the MPG you just posted is due to winter weather or do you think there is more to gain here. Certainly 40+ MPG from a 200+ HP car at 70MPH is pretty good. Just wondering where you think this is going.
Thanks
 

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What wheels/tires?
 

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Discussion Starter #5
You have a great car.
You've been really good at posting details of your progress along the way.
There have been a lot of things that have interested me in your posts across many forums.
Thanks for all your posts.
I'm curious about your fuel mileage. In another post either here or elsewhere, you mentioned you'd like to achieve 60+ MPG. (And I think I recall you getting nearly 65 not long ago.) Do you suppose the MPG you just posted is due to winter weather or do you think there is more to gain here. Certainly 40+ MPG from a 200+ HP car at 70MPH is pretty good. Just wondering where you think this is going.
Thanks
I've already had a full tank over 65mpg. I did it with pulse and glide on a round trip from Burlington to Boston and back. I expect with a kill switch I can probably push into the 70's with careful driving. It was 35F that I recorded these numbers and undoubtedly there will be some improvement in summer.


What wheels/tires?
Stock rims, RE92s in the rear at 45psi, Vredestein Quatrac 185/60r14 in front at 48psi.

Last night I swapped my snow tires on, Nokian Nordman 5's in 165/65r14, and this morning I averaged 48mpg on my commute to work with outside temps around 25F and snow on the roads. I was generally at 55-65mph.
 

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wait so you're running stock width tires with 3.5x the HP? Isnt' that sort of pointless? Doesn't it just break traction, even in 4th or 5th?
 

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Discussion Starter #7
wait so you're running stock width tires with 3.5x the HP? Isnt' that sort of pointless? Doesn't it just break traction, even in 4th or 5th?
I have a limited slip differential so I can put down power with both front wheels rather than just one. Plus, the car has a really silly weight distribution now, something like -150lbs in the back and +300lbs over the drive wheels, which is favorable for traction. In good weather it will keep the road even in 1st, and the car accelerates like a ballistic missile. 0-60 is similar to that of a current generation Corvette.
 

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That's awesome.
 

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So basically your K-swapped G1 gets about the same mileage as my OEM G1 MT... sometimes I don't like living on a mountain ;), where my commute is basically down and up the mountain 2 whole miles. I dropped below 50 mpg last winter.
 

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Awesome that’s my goal as well !

I don’t even have an insight and that all I think about 50mpg in Cali weather and 200whp!

dream daily
 

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So basically your K-swapped G1 gets about the same mileage as my OEM G1 MT... sometimes I don't like living on a mountain ;), where my commute is basically down and up the mountain 2 whole miles. I dropped below 50 mpg last winter.
I think your biggest problem is your short commute. Try a block heater so your car can be warmed up before heading out.
 

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Discussion Starter #12
Drove around 5 hours round trip for a work event. Outside temperature was 8F, maybe 1/3 of the trip was through a snowstorm with accumulation on the roads. Net elevation change was near zero. First and last 30 minutes were at 65mph, the rest of the trip was typically 50mph with some 40mph stretches. Averaged a hair over 50mpg on the way there and approx 49mpg on the way back.

EDIT: Tires right now are Nokian Nordman 5's at ~48PSI cold. I'm running 25mm spacers in the rear and much of the belly pan is missing right now.
 

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How are you tabulating your MPG?
 

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Discussion Starter #14
I use an MPGuino. It counts frequency and length of injector pulse, and compares it with the speed sensor to show MPG. I reset it at the beginning of a tank, it counts fuel, and at the next fill I compare gallons into the tank with how many gallons it counted and I can either adjust fuel flow rate up or down or slightly tweak the delay it has for injector opening. I'd say it's accurate within 1-2% right now.

This is probably similar to the method used by the cluster with the stock motor. Traditional OBD-based instrumentation doesn't take air fuel ratio into account, and ends up with wildly inaccurate numbers if the AFR deviates from 14.7:1, and I'm running slightly lean at part throttle.

 

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I have a limited slip differential so I can put down power with both front wheels rather than just one. Plus, the car has a really silly weight distribution now, something like -150lbs in the back and +300lbs over the drive wheels, which is favorable for traction. In good weather it will keep the road even in 1st, and the car accelerates like a ballistic missile. 0-60 is similar to that of a current generation Corvette.

So how much am I going to have to pay for one of these? :love:
 

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Discussion Starter #18
I think I was over $10,000 in parts but this build could be done in a lot less, depending on how much you can make yourself. Minimum of the major parts I think would be mounts ($500 from Hasport or Innovative), engine ($250-800 before shipping depending on which you want), transmission ($200-800), KPro ECU is nice to have but with certain engines you could use the factory ECU, and you'll need an exhaust system. The engine might come with a wiring harness already. If you use the RSX or Civic Si transmission you can bolt the cables to the Insight's stock shifter but you'll probably need cables. Maybe some converter boxes for tach and VSS signaling.

Where I sunk a lot of money was in the transmission (custom gears) to get RPM down as far as I did, and some other performance and economy modifications such as a balance shaft delete in the engine, different camshafts, 50 degree VTC actuator, featherweight flywheel, etc.

Every now and then I see a pretty basic but complete K Swapped Insight go up for sale on Facebook for as little as $4-5,000.
 

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Nice build. I would do one in a heartbeat...CA emission laws...lame
 
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