mobythevan Posted September 28, 2003 Share Posted September 28, 2003 I would like to have some baseline of where I am at before I do any more mods to turbo car. It looks like I only have two choices to measure performance, either stopwatch 0-60 or g-tech pro for like $70. Would the G-tech pro give me any idea what I am doing before and after the upgrade? I realize it is not the most accurate, but how accurate is it. It only gives 0-60, 1/4 mile, and peak hp right? Got to be better than stop watch method. Right now I am bone stock including fuel pump, injectors, FPR, stock computer, etc.. But I have MBC at 10psi, 2.5" mandrel downpipe, removed AAC, EGR. This winter I will be upgrading to MS, 240sx TB, 450cc injectors, intercooler, bigger fuel pump, maybe hybrid turbo. I would like to re-measure with the g-tech pro at each upgrade when it makes sense and see what has changed. But if the thing is not that accurate, then I'll just save the money and use the seat of the pants dyno. I don't care if it is always off by some amount, like it shows 120hp now and 140 after some upgrades, as long as it can indicate a gain or loss in hp. SO if I go out one day like last weekend and it just doesn't feel like it is running good I can see what it is showing. Quote Link to comment Share on other sites More sharing options...
Xander Posted September 28, 2003 Share Posted September 28, 2003 you might weant to checkout this thread. http://www.hybridz.org/phpBB2/viewtopic.php?t=25613&highlight=roaddyno Xander Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted September 28, 2003 Share Posted September 28, 2003 Well for one, of course it is probably going to show some improvement, if that's all you're looking for it to do... but ... do you really need the Gtech to show you that you're getting more power from those mods you're going to do? I think there is no question that those mods will add to the power you have now... Where are you getting a Gtech pro for $70 by the way?? I'd love to have one of those... anyways I've heard a lot of different things from different people but most seem to agree that the HP calculators on them are crap and will give you totally different readings every time you use it even if you haven't changed anything. However I have heard that they are more or less accurate with the speed measuring and give pretty accurate 0-60 and 1/4 mile times. However one thing about the 1/4 mile, when it gives you you're 'trap speed' it actually just gives a reading of your speed right at the end of the quarter, as opposed to how they do it at the the track where it's an average of the last 100ft or whatever, so the trap speed indicated by the gtech will always be a little faster than what you'd get at the track. Personally I would (and have) just keep using a stopwatch... the gtech looks like fun... and if I saw one for $70 I probably would snatch it up... but it just seems like one of those 'toys' that you'll play with for a week and be done with, unless you're modifying your car on a regular basis. The stopwatch method has worked well for me and is consistent as long as you do lots of runs (and who doesn't want an excuse to do lots of runs?). I haven't timed my turbo motor yet... haven't been able to perfect launching it well, but after timing my n/a motor like 50 times from 0-60 and 'perfecting the technique' I was able to get consistent readings on just about every run, in the mid 6 second range (sloooooooooowwwwwwwwww). Quote Link to comment Share on other sites More sharing options...
Afshin Posted September 28, 2003 Share Posted September 28, 2003 There are two G-tech the more basic one at ~$70 and the pro at $250 which seems absolutely great. It will give you 0-60, 1/8 ,1/4 mile time and speed, optimum shift points and a full graph of your HP and torque for the entire RPM range similar to a dyno run. It also gives you lateral G's and braking distance and maximum acceleration G's. It will also transfer all the data and plot to your computer as well. The principles behind the calculation are very sound and straight forward. My understanding is that it is actually highly accurate. The Hp reading is lower than the dyno because you are getting wind resistance and loss of HP. The results do not vary from run to run and I had heard from a good source (but did not verify it myself) that they have been used by one of the smaller car review teams. I understand everyone’s skepticism about the product since enough bogus claims have been made, however every now and then it is true. I had a basic g-tech before and it was great and my friend tried his against the track and it was very accurate and consistent. They have been around for a long time and continue to have an excellent reputation and have won some awards. Stop watch methods are phenomenally inaccurate no matter what anyone says and it would certainly be nice to accurately quantify changes in acceleration, HP, torque, braking and lateral G's as you make mods to the car. I just bought the new one myself and will put a post up as soon as I get the chance to fix my cigarette lighter and take it to an open road ( I have a huge work deadline at the moment). Quote Link to comment Share on other sites More sharing options...
mobythevan Posted September 28, 2003 Author Share Posted September 28, 2003 I'm going to hold off on starting the upgrades for another week then and get one of these to take a few measurements. If you look at their website they explain the two different products. The G-tech pro which is the old one(what I will get) and the new G-tech pro competition($250 model). 525, Since the new competition model came out, the old ones sell for around $70 on ebay. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 28, 2003 Share Posted September 28, 2003 Ive had the gtech original model for three years and I like it. My biggest problem is finding a level peice of road with no traffic to use it on. I tested my Stage 1 WRX in the pouring rain with A/C on, a full tank of gas, and a passenger - 0-60 in 5.7sec. I then tested my friends automatic WS1 Firebird and got 5.1sec (in the dry of course). I have not yet tested my Turbo 280Z........Any day now when the bad weather breaks. I like the gtech for its simplicity and repeatability. I would not rely heavily on the actual numbers it gives but rely rather on the change after the mods. Make sure you use the same peice of road before and after with closely matched weather conditions when looking for comparisons. Those new fangled models look great too..... Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted September 29, 2003 Share Posted September 29, 2003 Hmm all I know is I had a friend with a turbo supra... he would use the Gtech, the older model, and though the times seemed pretty close and accurate, it would give him hp readings of anywhere from 200hp to like 1000hp no joke!! He would get strange numbers out of that thing all the time, as far as hp and torque were concerned. In actuallity he was putting some 300ish to the wheels, dyno tested. You're right hand timing isnt that accurate at all but if you do enough runs you get pretty good at it. I had done it so much that my times rarely fluctuated more than half a second when timing myself by hand like that... and to me that can be as much attributed to how I launched the car as it could be to not starting or stopping the time right. It was accurate enough for me to see improvements in this or that mod, for instance when I put cam in... testing myself about 10 times before installing it, averaging those together, then quite a few times after having it installed... I was consistently running about .2 seconds faster 0-60. I agree that when dealing with tenths of a second no person is going to be 100% accurate with a stop watch but it gets you close enough to see if you're getting faster, IMO. Any ways now that I know the gtech can be had for less than $100 I will hopefully be picking one up soon for myself dont get me wrong I do think they are a cool gadget to have and do function well enough to merit the $$$. Now that I have boost to play with and can make adjustments on the fly like that, it'd be interesting to see what kind of gains 1psi of boost is worth Quote Link to comment Share on other sites More sharing options...
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