Since gear ratio has so much to do with 1/4 mile times and speeds, shouldn't the hp calculators take that into account? I know my 3.0 gears and my tranny not shifting into 3rd right are hurting my times, and I have alot of room for improvement, and I have no idea when I'm going to get it on a dyno. Mainly just thought I'd throw the question out there.
the calculator they have at hardcore50.com gives the disclaimer that the calculator is only as accurate as your car is... that is figuring the #'s on a car that is totally "dialed-in"...........with the correct gear and what not for the 1/4 mile.
I have often thought of the same thing. It seems like so many other factors besides weight and time would have some effect on the numbers- gear ratios, trannys, tranny ratios,tire size etc...... Like I said, it seems like it would not be very accurate. JMO Preston
and you are correct young grasshopper When using the calculator on a street car......its probably + or - 10 to 15%. Maybe more. IMO They are pretty accurate for a car that is set-up for racing. I would say with in + or - 5%. Again there is a lot of variables with the car, not to mention altitude, temperature, track conditions, driver ability and so on and on. Example: Stock street cruiser with street tires, 3.00 gear and fully dressed, Runs 14 second flat 1/4 mile. (all stock) Same car: Slicks, 4.11 gear and knock off about 300 pds. of dressing. Now it runs a 12.5 second 1/4. Is it making more HP? no, but it has been "tuned" for the calculator. Again, its only as accurate as you are. But its a neat tool to give you a "kind of ideal" what you got. And plus with the real detailed calculators, you can kind of tune your car or change things like gears and tire size and see what it says you will do.....might not be real accurate, but if you change some #'s on the calculator and it says you slowed down......might think/research further before making the change in real life. but the BIG BUTT is this: Ain't no fun punching bottons on a computer......to really know what your ride can do, getter' out on the strip and poor the coals to it! Then you know for sure
The guys have pretty much answered your question on calculators. I would just like to add my take on getting better times without changing hp ratings too much. From your spec's I think you need to seriously look at getting a deeper gear and some traction enhancers such as slap bars or cal-tracs. I also think your convertor could be a bit tight for the cam you have etc. Weight reduction will always help, and even some different driving techniques. Learned a long time ago not to dump tons of money in the engine to get a screamen demon motor and then try to run it with no other modifications to the rest of the car. HP must be able to go through the drivetrain and get to the ground effeciantly. Get online to one of the convertor mfg's and fill out one of their forms to get their recommendations for what stall you should have. Just that change and rear gears should make an improvement. Has rained for days here so I am getting a little keyboard practice in on the board. Sorry about that.
Hp calculators aren't accurate, but they get you close. As far as rear gears go, usually it doesn't make that much difference in reguards to the HP calc. The calc will actually show that you have more HP than you actually do if you have something like a 2.79 rear gear which will MPH better (usually) than...say...4.11's. The 4.11's give a better ET, but usually 1-2 mph slower at the most. There are exceptions of course. Most of the HP calcs require 1/8 or 1/4 MPH, tire size, gear ratio, weight and a few other inputs. ET is dependant on the first 300 feet of track, MPH is dependant on HP output. Thats why the calcs work on MPH, not ET.
Matt calculators are to be used in a perfect world...meaning there right if everything is working perfectly. The one I use you enter track length, ET and mph and the weight of the car and driver to determine HP. So you have to cut a .025 light, hook-up perfectly, shift perfectly and so on. Punch in my figures and it tells me I'm puttin out 389 hp which I know is incorrect because I've never had a "perfect" run. Matt posi will go a long way for you just as it did for me... I don't know if I would go much over a 3.75 gear if your using it as a cruiser. I'm running a 3.55 and like running 70 mph at less that 3 grand. Easier on the gas as long as I keep my foot out of it.
