Manifold I just finished for a client.
Top Mount S366 for SRT-4
Twin TiAL MVS wastegates
Divided T4
4" donwpipe.












And of course the Hoosiers! We're wrapping them now

 

I've always used rear TOE IN (1/8th inch total for both wheels) to keep the rear planted, never had much problems with understeer either so I was dealing with oversteer mainly

 

That exhaust is a work of art.

 

haha don't get me wrong i know your car is very fast and you build incredible machines. Im just saying sometimes a little bit of a slow car (less boost) can be a little bit quicker (lap times i mean lol) But keep up the good work i will deff follow this thread

 

Fronts will be about 30deg inside hot, i'm just sayin.

 

Ok,
I spoke with the Hoosier rep and he said I should have ideally no more than about 20 degrees difference from inner->outer tire... and then I told him I was planning on running toe out, and he then raised that to nearly 30 degree maximum difference.

I suppose I could try running less toe out to attempt to keep the tire temps happy. Do you think 1/16" out is acceptible? I would like to have some toe out, I REALLY liked the feedback

I've been reading RCVD, and from my understanding... the amount of steering torque transmitted to the steering wheel falls away as the limit of the tire is exceeded. By running that much camber WITHOUT toe out, my steering force is MUCH MUCH less. Of course its all dampened by the PS, but with the Hoosier slicks my assumption is that they will convey the limit via steering response and NOT audibly like the RE-01R's did.

 

Depending on how low you are running the car, I wouldn't run that much camber. Our car is 0 toe all the way around and 3.5 degrees front to achieve reasonably well balanced temperatures across the face of the tire. You also want to balance the amount of tire available for braking which is something we are fighting with right now.

Tire pressures, it might make sense to you that increasing rear tire pressures decreases grip, but that isn't always true. If you are at 34 f and 34 r and then go to 34 f and 36 r, I'd say chances are you would increase rear grip because you are within the normal working range of the tire. Now if you go from lets say 38 f and 38 r to 38 f and 44 r, well now you are outside the working range of the tires and would probably lose rear grip. Make sense? It all has to do with tire slip angles and a good place to read about that is here.

The last thing I will say is you should never focus on reducing grip either front or rear to make the car handle better... That's like dating an ugly girl and telling her to gain weight so her face becomes her nicer feature. I once read something that has stuck with me, if you have a problem with the front of the car, work there, if you have problems with the rear of the car, work there. If you feel the car is understeering horribly into turns, focus on making the front of the car grip better.

Dan

P.S. Your line on track is more important then anything else in regards to setting fast laps.
P.P.S. Girodisc Titanium Shims are the ****!
P.P.P.S. We used AMsoil DOT 4 Brake Fluid and will be switching back to ATE Super Blue most likely.

 

The power steering swamps out any tire feedback, these aren't exactly FSAE cars here.

Keep in mind that your experience thus far with how the car handles isn't doing you any favors. Where as you may have needed lots of toe out to get good feel in the car before, you're on the right track now to get the same feel with out needing all the toe. Street tires are sloppy compared to hoosiers. Massive understeer sucks, fix that and the steering will feel much better.

 

Understood. Good points, I'll make the toe out almost immeasurable!

Rawkus I see your point on the tire pressures. My assumption was that I had optimized or was within a psi or two of the premium setup... and was further raising pressure beyond that point. Of course if I'm in the weeds with low tire pressure, then raising the rears might actually improve rear grip.

You may not have read every post, but I certainly reiterate the point of not reducing grip to maintain balance, but to increase it on the corner that lacks.

I read the section on slip angles from RCVS, I'll check out that link you posted when I have some free time to read. Thank you for the link!

Experience on the track sure helps, but Hoosiers sure made a helluva difference!

Since you use the Ti shims... do you have them F&R or just front? I was considering picking up a set of fronts for the next event. lmk I know with the DTC60's and Hoosiers I'll be generating MORE heat than before.

Thank you all for your contributions! I really do appreciate it!

 

dont forget to get a good amount of caster in if possible...

 

A few things that may be of more help. I am a street tire driver, so I have no personal experienced with Hoosiers but, on our friend's Speed World Challenge RX8 the working pressure for their Hoosiers was 40 psi hot. They would make small adjustments from that point, but they always wanted 40 psi. Again, completely different car, but perhaps something to think about.

As far as not reducing grip, I'm picking up what your putting down, no need to reduce grip to gain balance.

On our car, we are using the shims just up front. You may find you create less heat because the Hoosiers and pads slow you in a shorter time frame that you won't be on the brakes as much. Regardless, these shims helped an amazing amount on our car and I would recommend them for anyone that does on track driving.
Dan

 

well the ringer driver that we're up against will be driving an R35 with 335 Hoosier A6's... I guess I just need to practice at this point and see what kind of lap times we're able to turn.

We need to be in the 1:09:xx range to take the Lap Record...and probably closer to 1:08:xx to beat the GTR.

I'm pulling some strings to make some things happen.

Found a nice tire pressure gauge 0-45psi as well as a Tire pyrometer with a nice case.
Borrowing an air tank... MIGHT be borrowing a lightweight seat.

Looking to make a carbon front splitter for some downforce.

I watched an in car video of that 1:10:xx S2000 and watched the course speed... mostly 28-37mph cornering speeds. He hit 76mph on the front straight before braking. I don't know how much the front splitter will help, but Bundy seems absolutely convinced it will increase grip. We'll see. I might have to throw back on the factory wing :P

 

At 28-37mph cornering speeds, the factory wing shouldn't be helping much... But since you're racing, every bit helps. Get a gourney flap on that wing aswell etc... Every little bit that makes a slight difference should help you.

 

rear diff won't be back in time, so I'm not sending mine. I'm hoping to borrow one from English to get rebuilt.... we'll see what Aaron and Luke say.

 

I'm going to wait on the rear diff... until the time between the July and August race.

I got all the bushings in and the coilovers on.
Hoosiers mounted

I bought some more brake parts
Girodisc rear rotors
ST43 rear pads
Girodisc Ti front shims
Girodisc caliper piston dust seals.

Tonight I'll set ride height and bleed the brakes. Alignment is on Friday.

Got my tire temperature probe I still need to replace the valve cover gasket and fix the catch can.

Griceiv,
I will run 1/64" toe out in the front