Approaching 60 MPG after the Drop!

Discussion in 'Fuel Economy' started by krousdb, Mar 6, 2006.

  1. krousdb

    krousdb Defiant NX-74205

    Before this morning, my best trip to work was 55.0 MPG. Today, under very similar conditions, it was 58.4! Same temps (28-30F), same road conditions (dry), similar wind conditions (less than 10 mph), same trip attributes (made the important lights). The only difference that I can find is the lower ride height. The benefit is better cornering (saving momentum) and longer, higher speed coasting.

    Of course this is not a very scientific test but at least the MPG didn't suffer. The ride was bumpier, but not at all unbearable. It didn't take long to get used to.

    My best trip home was 51.4 MPG at 41F, dry roads with a 10 MPH headwind. says that on the drive home it will be 37F, dry with a 9 MPH headwind. Hopefully I can improve upon the 51.4 personal best this evening.

    Later this week the temps will be 40's morning and 60's evening. Unfortunately rain is in the forcast. Not perfect conditions, but hopefully better than today.:D
  2. hawkgt647

    hawkgt647 Well-Known Member

    Excellent preliminary results!

    I like hearing about modifications & experiments, and the MPG gains from the "tweaks".

    Have you tried a warm air intake yet? Do you think it would benefit your Del Sol?

    When it's time for new tires, maybe a change to LRR, if they are made in your size.
  3. krousdb

    krousdb Defiant NX-74205

    Yes I have a warm air intake and grille block. I havent done any testing to determine what if any improvement that results. I did look at LRR tires, the Bridgestone RE92 and the Goodyear Integrity, but the Integritys have terrible treadlife, wet traction and snow traction and according to Tire Rack, the RE92's have the same shortcomings. If I didn't need to be able to get around in the snow, I would choose the RE92's. I am considering a set of summer tires on 13" Honda VX wheels (9 lbs each) with RE92's but I need to locate the wheels first.
  4. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Dan:

    ___I cannot wait to see where you push that monster too in mid-summer. I can see 65 + over a tank in the very near future! Talk about kicking @$ and taking names … Makes my Accord look like a fuel sucking pig ;)

    ___Nice job so far! I hope you try out those Air dams in front of the tires too. Honda and Toyota spent some wind tunnel time on those and there has to be something to it … Maybe some RE92’s for summer driving? I used them year round here in Chicago and they worked ok. Eric is from the Madison area and is still using them on his Insight. Not great in the wet and snow by any means but they were ok.

    ___Good Luck

    Last edited: Mar 6, 2006
  5. krousdb

    krousdb Defiant NX-74205

    Thanks Wayne, can you post a side view picture. It will help me visualize how to build and mount them.

    Yes, I was looking at the RE92's. But research at tire rack shows the 165/65/14 size used on the Insight is only 13 lbs and has a tread width of 5.0". The smaller 165/65/13 has a weight of 19 lbs, a tread width of 5.2 inshes and only 35 PSI rating. This leads me to believe that that particular size is very special and that using any other size may not give the good results expected. So that means that I really need to find 14" lightweight wheels, maybe from an insight or a Civic CX/HX.

    One upside is that with 13" and 14" tires, the ride height is lowered by 1" and 1/2" respectively. I am tempted, but it is difficult to justify the expense. Maybe someone will let me borrow the wheels/tires off of an Insight for a short time for testing purposes. Then, once the difference can be quantified, I could make an informed decision.
  6. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Dan:

    ___I have to get to the bank and then ready myself for work. Please remind me about this thread on Friday so I can upload a side profile of the dams for you.

    ___There are junked Insight’s around the country. Keep your eye’s peeled for a set being advertised from IC as they have been discussed time and again over the years. IIRC, retail was a crazy $340.00 per rim not including the RE92’s themselves! I bet you could pull a set off a totaled Insight for < $175 for all 4 including the RE92’s! I did not follow your del Sol closely enough to know your speedo error with the OEM rims and tires? Would the RE92’s diameter from an Insight bring you closer or move you further away from right on?

    ___The non-Insight RE92’s as found on the older Camry’s and first gen Prius I’s are definitely not the same as the Insight’s. Wear ratings and sizing are all wrong. If the Insight’s rims are a direct bolt on, you might have a winner … if the diameter is proper for your VSS?

    ___Good Luck

  7. Chuck

    Chuck just the messenger

    If this is "all" you could do - what would you have done with an Insight? :D

  8. krousdb

    krousdb Defiant NX-74205

    Lets find out shall we? Are you headed my way any time soon?:cool:
  9. krousdb

    krousdb Defiant NX-74205

    I will keep my eyes open for a set and maybe you can ask around for me? The Insight RE92's are 22.5" diameter which is exactly what the stock Del Sol diameter was. The would give me 57 actual at 60 indicated. No problem because I can adjust for that with the SuperMID distance parameter. And when I change to a CX transmission, 3.25 final drive vs. current 4.06, I will have to do it again. I have no idea what the speedo will say after that swap.
  10. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Dan:

    ___I will keep my eyes open for a set of RE92’s for you … That is to bad about the diameter being a bit too small though. The Insight’s register an approximate 2% distance over actual with the slightly undersized RE92’s as well :(

    ___And if you had an Insight for a week, oh my ;)

    ___Good Luck

  11. philmcneal

    philmcneal Has it been 10 years? Wow

    some stiff competition ahead to reduce global warming eh?
  12. krousdb

    krousdb Defiant NX-74205

    Well I havent gotten around to taping yarn on my trunk lid and watching for turbulence with the windows closed and then with the top off and the rear windows down... But I did have some interesting results today....

    Every weekend I drive to the inlaws house to check on it while they are in Florida. It is about a 25 mile round trip. The elevation is about 100ft lower at thier house than at mine.

    So the trip out was 60.11 MPG, starting with the engine fairly warm, about 130F.

    Before leaving for the trip back I removed the top and rolled down the rear window. Temp was 54F and the winds light and variable. While driving I put my hand out the rear window, over the trunk lid and could feel the air flow, so there is a possibility that the air flow could actually help the areodynamics by smoothing out the turbulence on the trunk lid due to the targa roof. Hopefully it offsets the drag created by having the roof off.

    The trip back home was 62.7 MPG at a 100ft+ elevation change.

    While this is not a scientifically valid test (really need to do two round trips, one with and one without the roof) it seems evident that driving with the roof off at 25-40MPH speeds does not significantly hurt FE.

    Current tank, which also includes the trip back from the gas station...

    32 miles, 59.5 MPG. :D :D :D

    Last tank, 591 miles, 54.42 MPG.:D
  13. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Dan:

    ___Keep those excellent results coming! I hope you get a chance to do some testing with the moon hubcaps as I see another area for a nice improvement with very little effort spent. Although you do have to like the looks???

    ___There is a Photoshop modded pic of a silver Insight out on the web I want you to look at. Give me a few hours and I will try and locate/post it. I think you might find a few things to make the del Sol a world class streamliner from that pic. I am tempted to moon cap the Accord but it’s already sitting at a decent .30.

    ___Good Luck

  14. krousdb

    krousdb Defiant NX-74205

    So I finally got around to taping yarn on my trunk lid. One row at the end of the lid, one across the middle and one across the front, near the rear window. It didn't take much speed to see what is going on back there. The rear ones flail about toward the rear of the car. But the front and middle rows immediatly flip over and flail about toward the front of the car. No matter what speed, same results. Rear window open with side windows open, no change. Rear window open with roof off, no change. One hell of a lot of turbulance.

    So I headed toward I-79 to take a highway test run to see what sort of mileage I can get now that I am SuperMID equipped. Temp was 60F with 8 MPH tailwind to start. Of course on the way back ot was a headwind. Terget speed 55 but I bled off speed going up hill down to 50, and let speed increase to 60 on the downhills.

    - 22 miles with an 8MPH tailwind, 58.4 MPG.
    - 22 miles with an 8MPH headwind, 56.5 MPG.
    - 44 mile RT, 57.4 MPG.

    What a pleasant surprise. I was only expecting 50MPG. The Prius is good for 65 MPG under the same conditions.

    Lots of errands today also.

    Current tank, 144 miles, 58.8 MPG.
  15. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Dan:

    ___That kind of FE is hot!

    ___To go along with that, here is that Photoshop modded Insight I promised you. It was a bit tougher to find then I had first thought …


    ___I have a pic of Billy’s Insight with the mirror removal for LCD mod you might want to consider as well?

    ___Good Luck


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