Autox with 2.4L Ion3 - help w/ suspension

[FunkyStickman]

Which SCCA rules are you getting these out of? I'm looking at a 2008 copy, and here's what it says under Street Prepared: (parts pertaining to Red Lines are highlighted) And it also says that our cars fall into their SP category relative to the stock class they run in. So if we're in DS, then we'd fall into DSP as long as we don't break the rules.

C. Induction allowances are as follows:
1. Carburetors, fuel injection, and intake manifolds are unre-
stricted, subject to 15.10.D. Alternate throttle linkage and
connections to facilitate installation of allowed induction
systems are permitted, but may serve no other purpose. If an
induction system item is allowed to be removed and its origi-
nal mounting bracket can be removed by simply unbolting it,
the bracket may be re-moved as well.
2. Except for standard parts as defined in these rules, the exter-
nal use while on course of liquids, ice, dry ice, refrigeration
systems, vaporized compressed gases, etc. to reduce the
temperature of the intake air charge is prohibited. Wrapping
of intakes with liquid-soaked fabric is not permitted.
3. As utilized only on engines originally equipped with forced
induction, induction charge heat exchangers (known as “in-
tercoolers” or “charge air coolers (CACs)”) are unrestricted in
size and configuration. Air-to-air CACs and radiators for air-
to-liquid CACs must be cooled only by the atmosphere, except
for standard parts. Body panels, fascias, or structural mem-
bers may not be cut or altered to facilitate CAC installation.
4. Turbochargers and/or superchargers (“forced induction”)
may not be added, changed, or modified (this does not allow
ceramic coating of turbochargers). On vehicles originally
equipped with forced induction:
a) No hardware changes or alterations to turbocharger(s) or
supercharger(s), in size or number, are permitted. Turbo-
chargers or superchargers may be updated/backdated
only in conjunction with the accompanying complete
engine unit.
b) No changes are allowed to waste gate(s) size, number, or
location. No changes are allowed to variable-geometry-
turbine (VGT) hardware.
c) No changes are allowed to supercharger drive system
pulleys. Belt tensioners may be added/changed to reduce
belt slip.
d) No changes are permitted to blow-off/pop-off valves.
e) Compressor bypass valves (CBVs) are considered part of
the air intake system, and may be replaced or updated/
backdated independently of the other components of a
forced induction system.
f) Boost regulation systems, either electronic or mechanical,
and electronic fuel cuts referencing boost pressure may be
altered or modified except as prohibited herein. Boost
pressure changes resulting from authorized changes are
permitted.

[scottherbert]

Originally Posted by FunkyStickman

Which SCCA rules are you getting these out of? I'm looking at a 2008 copy, and here's what it says under Street Prepared: (parts pertaining to Red Lines are highlighted) And it also says that our cars fall into their SP category relative to the stock class they run in. So if we're in DS, then we'd fall into DSP as long as we don't break the rules.

C. Induction allowances are as follows:
1. Carburetors, fuel injection, and intake manifolds are unre-
stricted, subject to 15.10.D. Alternate throttle linkage and
connections to facilitate installation of allowed induction
systems are permitted, but may serve no other purpose. If an
induction system item is allowed to be removed and its origi-
nal mounting bracket can be removed by simply unbolting it,
the bracket may be re-moved as well.
2. Except for standard parts as defined in these rules, the exter-
nal use while on course of liquids, ice, dry ice, refrigeration
systems, vaporized compressed gases, etc. to reduce the
temperature of the intake air charge is prohibited. Wrapping
of intakes with liquid-soaked fabric is not permitted.
3. As utilized only on engines originally equipped with forced
induction, induction charge heat exchangers (known as “in-
tercoolers” or “charge air coolers (CACs)”) are unrestricted in
size and configuration. Air-to-air CACs and radiators for air-
to-liquid CACs must be cooled only by the atmosphere, except
for standard parts. Body panels, fascias, or structural mem-
bers may not be cut or altered to facilitate CAC installation.
4. Turbochargers and/or superchargers (“forced induction”)
may not be added, changed, or modified (this does not allow
ceramic coating of turbochargers). On vehicles originally
equipped with forced induction:
a) No hardware changes or alterations to turbocharger(s) or
supercharger(s), in size or number, are permitted. Turbo-
chargers or superchargers may be updated/backdated
only in conjunction with the accompanying complete
engine unit.
b) No changes are allowed to waste gate(s) size, number, or
location. No changes are allowed to variable-geometry-
turbine (VGT) hardware.
c) No changes are allowed to supercharger drive system
pulleys. Belt tensioners may be added/changed to reduce
belt slip.
d) No changes are permitted to blow-off/pop-off valves.
e) Compressor bypass valves (CBVs) are considered part of
the air intake system, and may be replaced or updated/
backdated independently of the other components of a
forced induction system.
f) Boost regulation systems, either electronic or mechanical,
and electronic fuel cuts referencing boost pressure may be
altered or modified except as prohibited herein. Boost
pressure changes resulting from authorized changes are
permitted.

My take exactly!

Which means you can use sub-frame connectors (I have them), add an additional rear swaybar (I have one), add a stage 1 kit (it's ordered), add a cold air (don't need it), use any disk brakes (I already use Brembo & Hawk), use any springs (including lowering springs -- which I'm not a fan of for autocross), use any shocks (I have Konis), you can have the rear wheels 'shimmed' out to as much as 1.5 degrees of negative camber and you can take the front out to as negative as you want (I like 2.0 degrees of negative) and you can even add tow-out to the rear wheels if you're really fast (both ends negative next week), you can change to eurathane mounts (maybe), you can add a torque limiter (a 'Stiffy' -- maybe) and you can run any wheels and tires (so I'm going to have custom wheels made -- 17" X 10" wide, with about 15mm of positive offset -- to use 295/35 x 17 Hoosier A6s or 315/35 x 17 Kumho V710s), another reason to not like lowering springs since these wheels/tires will likely stick-out past the body edge.

I think the above is enough.

Scott

[Eagle_f90]

Re-read part c "No changes are allowed to supercharger drive system
pulleys" Which means no Stage 1 pully allowed.

[qwikredline11]

Originally Posted by Eagle_f90

Re-read part c "No changes are allowed to supercharger drive system
pulleys" Which means no Stage 1 pully allowed.

I understood that stage 1 is a tune only stage 2 is a pulley

[scottherbert]

Originally Posted by Eagle_f90

Re-read part c "No changes are allowed to supercharger drive system
pulleys" Which means no Stage 1 pully allowed.

There is no pulley change with a stage 1 kit, it's strictly new injectors and a reflash. Legal in SP. the Stage II has the pulley change.

Scott

[Eagle_f90]

Originally Posted by scottherbert

There is no pulley change with a stage 1 kit, it's strictly new injectors and a reflash. Legal in SP. the Stage II has the pulley change.

Scott

My mistake, I thought the Stage I had a pully change also. So then yes, legal in DSP

[Shabodah]

Moving from a 215 to a 315 seems like a bad idea without changing the gearing or torque output significantly. Furthermore, I'm not sure how far said tire would stick out of the wheel wells and how bad it would rub. What all tires have you been running in the past?

[scottherbert]

Originally Posted by Shabodah

Moving from a 215 to a 315 seems like a bad idea without changing the gearing or torque output significantly. Furthermore, I'm not sure how far said tire would stick out of the wheel wells and how bad it would rub. What all tires have you been running in the past?

I've been running Hoosier A6 225/40 x 17s and 225/45 x 17s. 295/35 x 17 Hoosier A6s are about the same diameter as the 225/45s (less than an inch taller than the stock 215/45 x 17 Dunlop). 315/35 x 17 are 1" taller (go to Tirerack and check-out the diameters for the tires). The biggest problem with the Redline is sliding (or spinning) the tires in the corners and/or under power (I have a qaife).

Summary Stats:
TIRE BRAND/MODEL SIZE DIAMETER TREAD WIDTH
Dunlop SP 9000 215/45 x 17 24.6" (stock) 7.9" (stock)
Hoosier A6 225/40 x 17 23.8" (-0.8") 8.9" (+1.0")
Hoosier A6 225/45 x 17 24.7" (+0.1") 8.8" (+0.9")
Hoosier A6 295/35 x 17 25.3" (+0.7") 10.8" (+2.9")
Hoosier A6 315/35 x 17 25.6" (+1.0") 11.6" (+3.7")

Both the 295/35 and the 315/35 are about 1% larger than stock -- not a big deal with as much torque as the Redline puts out. But differences in adhesion with almost 4" of additional tire with a 315 are HUGE!

The tires will likely sit outside the body width -- which is the biggest reason I have no plans of using lowered springs. Maintaining speed in the corners is the biggest potential gain I can make on an autocross track -- there's plenty of power, particularly if I can carry 1st up to 7000 RPM. Actually reducing the torque (1% taller tires) improves performance because there's less likelyhood of spinning the fronts coming out of a corner. Higner entry speed, higher cornering speed, and less tire spin on exit = faster times. I don't expect any rub, but it it happens, I'll deal with it. There are lots of suspention tricks to stiffen the suspention or increase roll stiffness (the reason for the added reas swaybar). BTW, the rear wheels are being shimmed out to 1.5 degrees of negative camber tomorrow -- and the front camber is being upped to 2.0 degrees of negative. Did I mention that I usually drive this only to autocross events, not normally on the street, it's usually garaged.

There are a number of very fast DSP & FSP cars racing in this region with tires as much as 2-3" outside the body -- BMWs mostly -- and some very low HP cars (Rabbits and Scirrocos -- <110 horses) with huge rubber and very high corning speeds.

Scott

[Shabodah]

I'm personally running 245/50r16's myself, for many of the same reasons you list. It does look like you've done most your research pretty well, but don't forget the effects of a heavier wheel & tire combination. Having messed with things a bit, I personally would recommend going with a tire wider than 255 if you ever intend on driving on them on the street in the redline. If you're buying track only wheels and tires, that's fine, but most people do tend to tell themselves they are "track only" and then drive them on the street anyway.

[BigBrother]

First - to reiterate, yes, we are in DSP.

Second - Poly mounts are legal in STX, and so is HP Tuners. You can't change the injectors in ST, but you COULD get the stage 1 flash to get the higher redline and retune w/ HPT to keep your 42# injectors. As long as you run premium fuel only, you should be fine. Regardless - you don't have to run in SP if you don't want to just becuase of poly mounts.

Third - I think you'll find that tire idea not as swell as you think. Try it - you may be right and I wrong - but that's a LOT of tire under a car and almost all of the extra width will be outside. That's good - except it changes your scrub radius DRAMATICALLY, which will make the cars turn-in awkward. Also - hard to tell how the EPS will handle it. I really think that lowering the cars CG and tuning the suspension properly in conjunction with 245/45/17 rubber would out-handle a stock ride height on really wide tires. Maybe not out-grip, but certainly out handle. Autocross is a grip race - but it's also a handling race. If it was an oval with constant radius turns, sure - but it's not. I think you'll learn to hate slaloms with those shoes on. I could be wrong though... Oh - and your math is WAAAAAY off. a one-inch increase in radius - almost 2" overall diameter - is a LOT more than 1%, lol. In fact, it's almost 10%. I'm all for gearing it up a little for 1st, but teh VAST majority of an autocross course is spent in the middle of 2nd. I wouldn't want to lose that much gearing in the sweet spot to gain a tad more throttle at exit, dude. Modulate the throttle better, lol. A rear sway and stiffer springs - a good bit stiffer in back - will increase the effectiveness of the stock LSD many times over, so put some trust in it. Or try a very light left foot brake action with the hammer down leaving a corner - works wonders for getting teh LSD involved if you're getting too much spin. Oh - and more negative camber, too. I've got -2.5/-2.7 on stock suspension on 245/45/17 Hoosiers, and it's not enough according to the pyrometer. If you're not taking tire temps, you don't know if your camber is right.