Thread: P11 Auto-X Setup help

Here is a quick video just to give you an idea of how the car runs and how tight the course is setup. this is with a sr18(long ratios) open diff gearbox.

Judging by those videos, your front tires are constantly being over worked in corners. I can hear them screaming first immediately which means stiffen the rear, conversely, loosen the front, in whatever way you want.

That open diff is certainly killing your ability to put the turbo power to the ground.

As well as I had the 235 tires on 7" wide wheels which was horrible. maybe why the tires do what they did in those runs. they are now on 8" wheels and are 100 times better. I had to run 45psi in the tires before to get any repsonse and lessen the roll when on the 7" wheels. My camera was acting up and could not record any runs of the most recent one. i hope to get some this weekend.

I install a p11 lsd GB last week so that has been dealt with. need to save up for an aftermarket diff though since this one has seen better days. but that to be added to the bottom of the list because of cost.

Suspension-wise, lose the front bar, increase the rear rate and decrease the front rate. If you haven't already, have the ream beam bent to zero toe. You shouldn't be so much concerned with body roll as you should be with chassis rotation, or the lack there of, in your case. Plowing through turns and getting on the gas late in the turns is the slow way around. When taking those 90 and 180 degree turns in the video, your car should want to oversteer the entire way around the turn. If you're not finishing it with a slight counter steer at corner exit, it isn't rotating enough. 45psi cold is too high. You're actually decreasing contact patch at those pressures. Start @ 38F 32R and tune from there. In wet conditions, lower works better...like sub 30's.

The other glaring issue I see is your car's power delivery. It's either on or off. It's either roasting the tires or bogging. If you're serious about improving times, I'd look at lowering the power or somehow make it more linear.

Loving the feedback guys, a lot of information here, cant thank u all enough. Gonna work on the beam for next year. i have a parts p11 that I can take out the beam to work on. I can disconnect the fsb and test it out, do you think it would be worth swaping the springs, as in using the 600lb in the back and the 400lb in the front?

I only used 45 when i had the 7" wheels, with the 8" wheels i am around those numbers. I might have used 36 last time when i was open diff. Will try it with ur numbers this weekend.

IMO the power delivery is fairly linear, but at that event with the open diff and long final drive ratio did not match so I had to hold out with the power and in turns the inside wheel just lights up with little power. i have a GT28 BB turbo from a S15 silvia so it has good power delivery. I just could not use the power as you can see. So it does seem that the power band is spikey.

My butt dyno tells me that peak power is somewhere between 3800 and 4500.
i will get my camera working for this event to have some good comparison videos before and afer the GB swap.

Swap the springs and see what happens. Just make sure they are they same diameter and length before you do so.

The current front springs are 8" tall and 2.5" dia, the rears are the original Front tein springs, 7" tall and 2.5". The original rear spring is a 8" spring so should fit if I use the oem top hat. I will give this a try.

Some other tuning things you can do once the springs are sorted are alignment settings and ride height. If you need more bite in the front put negative camber on the front using Kyle's hook up. Start @ zero toe and move in the direction of a little tow out if you need more turn in. Since you have CO's, having the car corner balanced would also something to look into if you're looking to get the most out of the car.

The other thing to look into are lighter wheels than what you have in the picture. That's make a huge difference. The whole car will feel lighter including the steering response. That's a big advantage when you're tossing it in the tight stuff.


Edit: Corrected comment about camber plates on a P11....doh!

P11 has no struts therefore camber plates are out of the equation.

Post corrected....p11's blah!