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Since making the gear change would you say that your car has more or less of a tendency to spin the rear wheels when accelerating from a stopped position?
I am looking for maximum stoplight to stoplight performance. Currently Jags setup is "I believe" to limit rpm to 6500 and use the supercharger to make torque. I have always felt that a 7500 redline is way more versatile. So what I am thinking about doing is installing a larger supercharger pulley (Under drive instead of the usual overdrive), run the 2 speed rear with a very low gear, increase redline to 7500 and run a programmable throttle stop. So I would limit the throttle opening from a 0mph situation (When in manual gated mode) so that the maximum amount of torque will be applied to the tires without wheel spin. The throttle stop will be stepper activated and programmed to increase the throttle opening as MPH increases thereby providing maximum constant torque to the rear wheels. I think this may also provide better mileage when back in the stock final drive ratio as the supercharger will consume less power and make less heat and belt life will be improved as well.
I don't see 7500 being a problem as long as the chains/guides are in good shape. Any thoughts based on your experience?
Much less tendency to spin the tires, but that is due to LSD as opposed to the normal one wheel fire open diff from the factory. I also run 285s in the rear which helps hook up. If the gears were changed to 3.58 w/o LSD obviously it would spin the one tire even easier, but I have created a great balance imo. I can brake stand it, but when I let off the brake it just hooks up almost immediately and goes. I made a custom rear sway bar so I can "play" on the track more and take advantage of the LSD at the limits and have some fun. As you can tell I usually don't just throw parts at a job just to say I did, its usually for a purpose.
Personally I don't think increasing rev limit with an m112 is going to help you. Efficiency and output runs out much earlier than 7500. If you came to me and I was doing the work, I would recommend throwing on a Kenne Bell and just throw in an LSD with 3.58s, pretty much a proven set up and I bet you would be happy. But since i'm not doing the work, its all you buddy . Plus with your background I could see why you would want to lean toward your own engineering.
Hood vents are actually a donation from an '87 trans am, saw them at a junk yard one day and had to have them! They purpose dually to let some extra air flow over the intercoolers and I have it cut so it flows air directly into the air box.
Since making the gear change would you say that your car has more or less of a tendency to spin the rear wheels when accelerating from a stopped position?
I am looking for maximum stoplight to stoplight performance. Currently Jags setup is "I believe" to limit rpm to 6500 and use the supercharger to make torque. I have always felt that a 7500 redline is way more versatile. So what I am thinking about doing is installing a larger supercharger pulley (Under drive instead of the usual overdrive), run the 2 speed rear with a very low gear, increase redline to 7500 and run a programmable throttle stop. So I would limit the throttle opening from a 0mph situation (When in manual gated mode) so that the maximum amount of torque will be applied to the tires without wheel spin. The throttle stop will be stepper activated and programmed to increase the throttle opening as MPH increases thereby providing maximum constant torque to the rear wheels. I think this may also provide better mileage when back in the stock final drive ratio as the supercharger will consume less power and make less heat and belt life will be improved as well.
I don't see 7500 being a problem as long as the chains/guides are in good shape. Any thoughts based on your experience?
Thanks
PS where did you get the Hood Vents?
May I ask how do you change the 6200rpm rev limiter in stock Denso ECU or remove other limiters in this box?? How do you modify gear change rpm from max 6000rpm in EGS51? I guess you do not have plan to change all the engine and transmission control units to aftermarket ones. Do you know how soft the stock valve springs are if you try 7500rpm? When you change upper or lower pulley you just make the same power at lower rpm. Stock M112 almost dies over 5500rpm if well overspinned.
I did figure that I would need to change the valve springs although they dont need to be super strong due to the relatively low valve train mass. Since these cars have dual cams one can alter the cam timing to shift the power peaks around a little or enhance cylinder pressure. For 7500 I would definitely be wanting to run a ms3-pro ecu which looks to be awesome ! It has sooo much tunability and it speaks canbus and has outputs for methanol/water injection etc. so it would really be slick. I also don't think it will freak out and put you in limp mode at in opportune times. Hearing that wheel spin is just not a problem with a LSD is going to keep me restrained. I will do the rear end first and then add torque until it won't take it.
I have decided to put a 6 speed and the 7500 mod in my XK8 with probably a 3.25:1 gear
PS for 7500 I said that I would slow the blower so the blower speed was the same (at 7500) as a 3# pulley is at with stock ecu at 6000 The blower speed is a limiting factor just like a propeller diameter is the limiting factor in an airplane. All hell breaks loose when any part of it goes supersonic
08-17-2016, 07:50 AM
. Plus with your background I could see why you would want to lean toward your own engineering.
