jevs Posted September 2, 2014 Share Posted September 2, 2014 (edited) I already placed my order because they are having a 15% off sale. I used the gauges recommended by Brunton except I customized them to my own liking and added turn signal and high beam indication to the speedometer and the shift light option to the tach. Anyway, without thinking about it, I ordered the 160 MPH speedo that was recommended. However, I know of at least one car with my motor that is hitting 170+ on track. I am wondering if I should change my order to a 180 MPH or 200 MPH speedometer? If so, which one? See pic for the three options in the style I came up with. Edited September 2, 2014 by jevs Link to comment Share on other sites More sharing options...
powderbrake Posted September 2, 2014 Share Posted September 2, 2014 At 170 mph in a Seven.... who has the time or the guts to look at a speedometer? Link to comment Share on other sites More sharing options...
jevs Posted September 2, 2014 Author Share Posted September 2, 2014 The camera pointed at your speedometer Link to comment Share on other sites More sharing options...
xcarguy Posted September 2, 2014 Share Posted September 2, 2014 jevs, Ran Speedhut in my Birkin; nice gauges. I've had my relatively small 346 cid LS6 powered car near the limit of my 160 speedo with a little room to spare. If I had a choice, I'd opt for the 180 . . . . or the 200 if your a complicated man. :jester: This may very well be something you have already considered, but on a more serious note, if you plan on running your car well into triple digit speeds (as I know you are ), you will need to address the issue of adding down force to the car. M-Spec or not, the inherent design of these cars transfers weight to the rear wheels at speed. John Meyer, who hit 170+ at VIR running the UTCC, ran with a large wing up high and just forward of the roll cage (about mid chassis). Without down force at such speeds, your front end will have a weight deficient. Link to comment Share on other sites More sharing options...
jevs Posted September 2, 2014 Author Share Posted September 2, 2014 Changed my order to the 200 MPH. This makes it future proof and the resolution difference is pretty insignificant as far as choosing something lower. The ZL1 Camaro and the Corvettes have 200 MPH speedos. The ZL1 top speed is 184 MPH. I figure if someone is hitting 170's on track with the same motor, that is going to be right at the extent of the 180. If they ever put it on the salt flats they might peg the speedometer This makes it more future proof if anyone buys it and turns it into a track only car or something. I will still have no problem telling I am going about 55 MPH. Link to comment Share on other sites More sharing options...
MightyMike Posted September 3, 2014 Share Posted September 3, 2014 I went with the 200mph speedo in my Storker. Kids love it. Link to comment Share on other sites More sharing options...
Kitcat Posted September 3, 2014 Share Posted September 3, 2014 Didn't MigetRacer hit 187 mph at the backstraight of VIR in his V8 Stalker? He started this whole V8 in a Stalker trend. That was with lotttsa wing as I recall (and a pretty wimpy roll cage, at least to my fading eyesight). I know 120 in my Caterham feels like 200 mph! Link to comment Share on other sites More sharing options...
subtlez28 Posted September 3, 2014 Share Posted September 3, 2014 I had to go look at mine, I couldn't remember. I have a 160 mph speedo. The GPS one. However, I have my fuel gauge in the speedo, so that took up some real estate. I offset mine to the passenger side, to add to the thrill for them. I was watching Scott's when I got my ride the day I picked up my kit. I'm sure my car is capable of over 160... But in any event where that really matters, like standing mile or salt flats... Timing equipment will give me the magic number when I outrun my speedo. The two main tracks I run are around 2 miles long (road courses), so I won't see over 160 too often... Link to comment Share on other sites More sharing options...
xcarguy Posted September 3, 2014 Share Posted September 3, 2014 Didn't MigetRacer hit 187 mph at the backstraight of VIR in his V8 Stalker? He started this whole V8 in a Stalker trend. That was with lotttsa wing as I recall (and a pretty wimpy roll cage, at least to my fading eyesight). I know 120 in my Caterham feels like 200 mph! John hit 173mph at VIR: QUOTE=midgetracr;58656]The calculation used the following data: 6791 RPM from datalogger, 3.23 rear axle ratio, 0.82 5th gear ratio in the TREMEC TKO 600 5 speed trans, 71.3" actual measured tire circumference from Goodyear 22.5x10.0x13 slicks, 60 minutes per hour and 5280 feet per mile. This yields 6791/(.82*3.23)*(71.3" /12) *(60 /5280) = 173.12 MPH The RPM data was from my AIM EVO3 data logger on the quickest lap during timed session #1, measuring the tire with a tape measure, specs from TREMEC on the trans and counting teeth when I installed the differential gears. The above neglects both tire slip (which I think is minimal because of the downforce at that speed) and tire growth because of centrifical force which I have no way of estimating. Using the above formula it would require 7060 RPM or a larger tire to go 180 MPH if my math is correct. Because the soft rev limiter begins to retard timing at 7000 the engine will actually rev that high even if the limiter was not changed. I think the valve train would be OK to around 7500 but have never tried it. 200 MPH would require a narrower 80" tire to fit inside the fenders. Link to comment Share on other sites More sharing options...
jevs Posted September 3, 2014 Author Share Posted September 3, 2014 I noticed my VW Passat Diesel has a 160 MPH speedometer. This sealed my faith in my decision to get the 200 I also had a couple past cars with 200 speedos and I never really noticed it. The tiny resolution loss is a non existant issue, so why put anything in that the car could potentially peg.... Link to comment Share on other sites More sharing options...
Croc Posted September 4, 2014 Share Posted September 4, 2014 I think you are all wimps - go for 220mph! :jester: Link to comment Share on other sites More sharing options...
jimrankin Posted September 4, 2014 Share Posted September 4, 2014 Hey, just go digital and everything up to 999 MPH shouldn't be a problem. Oh, just thought of a problem, digital might have a "highest speed reached" memory so there goes the "I'm sure I hit at least" slightly upgrades story. Link to comment Share on other sites More sharing options...
BusaNostra Posted September 4, 2014 Share Posted September 4, 2014 (edited) Yeah! just like JIMRANKIN said....digital and peg or wot that pedal all the way to infinity! I did it once and I jammed it to 999 mph....what a ride! hehehe ! Edited September 4, 2014 by BusaNostra Link to comment Share on other sites More sharing options...
xcarguy Posted September 4, 2014 Share Posted September 4, 2014 Hey, just go digital and everything up to 999 MPH . . . . shouldn't be a problem. Okay, Jim's new forum name . . . . . . . Rocket Man. :jester: Link to comment Share on other sites More sharing options...
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