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Last Post 29 Oct 2014 10:43 AM by  Nathan Atkins
STX Weight and power
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dwx
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02 Feb 2013 03:33 PM
Don't some of the mods on the MS3 cause the boost to increase as a result? I thought I had read something about 2-3 PSI increases based on some bolt-on changes. Not that the MS3 is the only car which this happens with, the WRX/STi also can be "influenced" to boost spike based on exhaust changes.
murph1379
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03 Feb 2013 03:38 PM
I'm sure the boost will go up with increased exhaust flow, but is more power to the front wheels really what the MS3 needs? Seems to me it already has 100hp or so more than it can really handle.
Silverspeed3
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04 Feb 2013 12:51 AM

Agreed, we don't "NEED" more power, but if it's there for the taking.....

I have yet to have my car tuned, but my guess is there will be alterations to the fuel tables in the tune when I do. That said, and I am a noob to tuning, am I modifying the "fuel system"? As per the rules, fuel pressure regulators are legal. This may be a stretch, but with direct injection, my cam driven fuel pump IS my pressure regulator. I'd like to avoid upgrading my pump just because of the expense alone, but the way I read the rules, I think I have a legitimate argument that if swapping regulators is legal (and therefore allowing higher pressures at the injectors) I'm good with the upgrade. Now that I write this, I'm thinking this is a whole different thread I should be starting.... But I can't stop myself.

"The engine management system parameters and operation may be modified only via the methods listed below. These allowances also apply to forced induction cars, except that no changes to standard boost levels, intercoolers, or boost controls are permitted."

"Fuel pressure regulators may be replaced in lieu of electronic alterations to the fuel system. It is not permitted to electronically modify the fuel system AND replace a fuel pressure regulator."

justint5387
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04 Feb 2013 02:20 AM
murph1379 wrote:
I'm sure the boost will go up with increased exhaust flow, but is more power to the front wheels really what the MS3 needs? Seems to me it already has 100hp or so more than it can really handle.

The boost goes up to around 17psi with the changes. The car does have a lot of power for FWD, that's why I didn't spend much time trying to get more power out of my tune.

The new tires with the reported stiffer sidewall will help the MS3 since it has a limited amount of front camber. Gearing is still an issue at national course tho.

Impala SS AutoXer
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Posts:249


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04 Feb 2013 02:15 PM
Silverspeed3 wrote:

Agreed, we don't "NEED" more power, but if it's there for the taking.....

I have yet to have my car tuned, but my guess is there will be alterations to the fuel tables in the tune when I do. That said, and I am a noob to tuning, am I modifying the "fuel system"? As per the rules, fuel pressure regulators are legal. This may be a stretch, but with direct injection, my cam driven fuel pump IS my pressure regulator. I'd like to avoid upgrading my pump just because of the expense alone, but the way I read the rules, I think I have a legitimate argument that if swapping regulators is legal (and therefore allowing higher pressures at the injectors) I'm good with the upgrade. Now that I write this, I'm thinking this is a whole different thread I should be starting.... But I can't stop myself.

"The engine management system parameters and operation may be modified only via the methods listed below. These allowances also apply to forced induction cars, except that no changes to standard boost levels, intercoolers, or boost controls are permitted."

"Fuel pressure regulators may be replaced in lieu of electronic alterations to the fuel system. It is not permitted to electronically modify the fuel system AND replace a fuel pressure regulator."

The way that ST has traditionally interpreted this is that you can do the fuel regulator OR an ECU tune (which is "electronically modify the fuel system") but not BOTH.

Given that, it has usually been to advantage to do the ECU over the FPR...but it'd be interesting to see if there are any cars where the opposite is true.

jeffh
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Posts:258


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04 Feb 2013 04:40 PM
Impala SS AutoXer wrote:
Silverspeed3 wrote:

Agreed, we don't "NEED" more power, but if it's there for the taking.....

I have yet to have my car tuned, but my guess is there will be alterations to the fuel tables in the tune when I do. That said, and I am a noob to tuning, am I modifying the "fuel system"? As per the rules, fuel pressure regulators are legal. This may be a stretch, but with direct injection, my cam driven fuel pump IS my pressure regulator. I'd like to avoid upgrading my pump just because of the expense alone, but the way I read the rules, I think I have a legitimate argument that if swapping regulators is legal (and therefore allowing higher pressures at the injectors) I'm good with the upgrade. Now that I write this, I'm thinking this is a whole different thread I should be starting.... But I can't stop myself.

"The engine management system parameters and operation may be modified only via the methods listed below. These allowances also apply to forced induction cars, except that no changes to standard boost levels, intercoolers, or boost controls are permitted."

"Fuel pressure regulators may be replaced in lieu of electronic alterations to the fuel system. It is not permitted to electronically modify the fuel system AND replace a fuel pressure regulator."

The way that ST has traditionally interpreted this is that you can do the fuel regulator OR an ECU tune (which is "electronically modify the fuel system") but not BOTH.

Given that, it has usually been to advantage to do the ECU over the FPR...but it'd be interesting to see if there are any cars where the opposite is true.

I read the rule as Silverspeed as well. Didn't consider a reprogramming to be an electronic modification. Maybe it is in some people eyes. If the service manual calls the fuel pump the fuel pressure regulator then it could possibly be changed in addition to a reflash..

Impala SS AutoXer
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04 Feb 2013 06:23 PM
Personally, I'd get a clarification from the STAC before showing up at a big event with both FPR and ECU mods...
VT2WA29
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04 Feb 2013 06:56 PM
justint5387 wrote:

Stock boost and stock fuel pump internals? I don't even make that much running higher boost for track...

I remember Gen2 MS3 having to upgrade fuel pump internals just from intake and cobb stage1 tune. The way I read the rules, fuel pump internals can't be changed for ST

The boost tables and fuel pump is stock. You should keep an eye on the fuel pressure as some Gen 2's stock fuel pumps can't maintain the 1650 psi demand, however, some can. You have to test a few of them to find one that is strong enough and continuously monitor it to ensure you are constantly maintaining 1650+ psi.

Knowing a person with a dozen stock Gen2 fuel pumps laying around a testing machine for them helps. :)

I do believe I currently hold the record for Gen 2 hp on stock boost levels, stock turbo and stock gas (no E85). The tuner I used was trying to get 350 hp, but the closest he could get was around 340 hp, I had him detune it a touch since the car will be put under enough abuse. He has a few people who are running stock boost, stock turbo but tuned with E85 running upwards of 360 - 375 hp, but it wasn't a route I wanted to do.

(I don't think a MS3 Gen 2 or 1 will be a competitive enough car in autocross to really warrant pushing the performance to an extremely high degree. Intake/inlet and cat-back exhaust with tune with some minor suspension mods, cornerbalancing and aggressive alignment are enough for me)

All this is a moot point though, I currently run 235/45R18 tires on the car and running 245+ would rub. Rolling the inside of the fenders (can't change the external contour per the rules) might get me the 245, but it won't make that much of a difference. My guess is that in second gear, I can only get down 75% of the power I'm making anyways.

Now on a track, 3rd and 4th gear are awesome though!

Charlie Davis
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Posts:440


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04 Feb 2013 08:36 PM

1) I'm quite certain that changing an ECU tune is considered "electronic alteration" and that you can either do that or a fuel pressure regulator but not both.

2) A fuel pump may regulate fuel flow, but it is NOT considered a Fuel Pressure Regulator. Its primary purpose is to pump fuel, so it is in fact a fuel pump. I believe that a clarification would reveal that the interpretation of FPR is one that only regulates and does not pump.

I think any other interpretation would be considered a "Tortured interpretation of the rules."

You really should get a clarification. Really. Seriously.

Silverspeed3
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04 Feb 2013 09:11 PM
I agree that clarification is required and I will do so prior to making any changes to my car. I have a downpipe to install, but I'm too chicken to do it until I do the pump. But if it bumps me out of STX I won't install the pipe and just do an ECU tune. In the end, I'm not going to challenge anyone in my car at a national event unless someone starts to design courses without turns. So who can provide the official clarification of the rule? Thanks.
Charlie Davis
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05 Feb 2013 12:57 AM
Silverspeed3 wrote:
I agree that clarification is required and I will do so prior to making any changes to my car. I have a downpipe to install, but I'm too chicken to do it until I do the pump. But if it bumps me out of STX I won't install the pipe and just do an ECU tune. In the end, I'm not going to challenge anyone in my car at a national event unless someone starts to design courses without turns. So who can provide the official clarification of the rule? Thanks.

Write the Solo Events Board at sebscca.com.

jfossum
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05 Feb 2013 07:55 PM
Charlie Davis wrote:
Silverspeed3 wrote:
I agree that clarification is required and I will do so prior to making any changes to my car. I have a downpipe to install, but I'm too chicken to do it until I do the pump. But if it bumps me out of STX I won't install the pipe and just do an ECU tune. In the end, I'm not going to challenge anyone in my car at a national event unless someone starts to design courses without turns. So who can provide the official clarification of the rule? Thanks.

Write the Solo Events Board at sebscca.com.

While I would never discourage someone from getting a clarification, I think if you read the rules in full (or better yet, read older versions to see how they have evolved), you will see it is pretty clear that a fuel pump is not a regulator and that a reflash is an electronic modification.

Jim

tkm
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06 Feb 2013 11:44 AM
If I had a MazdaSpeed3 (and I did at one time, an '09 GT), the VERY LAST thing I would be worried about is power. Getting that car to turn properly takes an act of your favorite deity, and even then that may not be enough. Spend the money elsewhere--like a very trick suspension setup and time at a test and tune trying to get the car to behave properly.

Regardless, a 3000lb+ FWD car that already has too much power down low (and not enough up top) is a fight that I would not choose to fight. Good luck.
justint5387
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Posts:176


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06 Feb 2013 04:26 PM
tkm wrote:
If I had a MazdaSpeed3 (and I did at one time, an '09 GT), the VERY LAST thing I would be worried about is power. Getting that car to turn properly takes an act of your favorite deity, and even then that may not be enough. Spend the money elsewhere--like a very trick suspension setup and time at a test and tune trying to get the car to behave properly.

Regardless, a 3000lb+ FWD car that already has too much power down low (and not enough up top) is a fight that I would not choose to fight. Good luck.

And a OS Giken LSD

Silverspeed3
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06 Feb 2013 11:00 PM
To each their own.... I enjoy the car on the street and that is it's main job. Point A to point B and put a smile on my face while doing it. I could drop $3K on a LSD that might buy me a few tenths but the downpipe (got mine used) can be enjoyed everyday on the street for a great deal less. I realize the limitations of the car (I knew them when I bought it), but it's cheap (relatively speaking), reliable, and does reasonably well at local events. The fact of the matter is I could drop $10k into the car pulling out weight, adding trick shocks, and every other aftermarket piece I can find for the car and it's biggest limitation would still be me. It's fun to try to make a wrong wheel drive hang with other street driven cars of all variations.
TeamRX8
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08 Feb 2013 01:39 AM
Charlie Davis wrote:

1) I'm quite certain that changing an ECU tune is considered "electronic alteration" and that you can either do that or a fuel pressure regulator but not both.

2) A fuel pump may regulate fuel flow, but it is NOT considered a Fuel Pressure Regulator. Its primary purpose is to pump fuel, so it is in fact a fuel pump. I believe that a clarification would reveal that the interpretation of FPR is one that only regulates and does not pump.

I think any other interpretation would be considered a "Tortured interpretation of the rules."

You really should get a clarification. Really. Seriously.

Just out of curiosity, how to you propose proving someone having done it? A clarification is just a paper tiger if it can't be enforced. And if that wasn't enough fun for one day, clarifications have been proven to be incorrect too ....

mrazny
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Posts:462


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08 Feb 2013 10:28 AM
Let's just say something like this happens...

Someguy in the same car doesn't go on forums. His reading of the rulebook also went the way of either/or. Finds another racer with the same car, but his reading was AND.

The paper tiger might stop the first guy from protesting the second. Not every time, and some other guy introduced in the mix changes the variables and all that.

But it isn't that difficult to ask for a clarification, and there are scenarios where it helps. Still worth it even if it isn't a catch-all. Or do the either/or and not worry.
mlane350z
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08 Feb 2013 12:04 PM
Somewhat speculative, but also confirmed with a few people that have ITR's...

Mid-High 2300's
190-195whp
Fair
Veteran Member
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09 Feb 2013 12:52 AM

We gave up on STX in our 2011 Mustang GT in late 2011, as it was never competitive no matter what tire brand or tricks we threw at it. Way too heavy for the class limit 265mm max width.

In STX trim we got it down to just under 3450 lbs (see above, with the temporary 18x10" wheel/275mm tire "STU" set-up, which worked a lot better than the 9" wheel/265mm tire. This was before the 2005-2013+ Mustang GT was locked into STX). Power was too easy to make... 430 whp with a cold air + headers, in STX legal trim. See the dyno below.

Power means nothing if you cannot use it. It was absolutely hopeLESS.

This car has no business being in STX, where it outweighs most cars in the class by 600 pounds or more. And yet it uses the same max tire width. In a word - F*CKED. It was more enjoyable in STU trim, but it will still lose badly there to 2900 pound EVOs (with almost the same power levels, but AWD, so it can actually use it)

Just my pessimistic two cents, about a stick axle heavyweight in a flyweight class. :) There isn't a place for 3200+ pound RWD cars in Street Touring, yet.

Torino1985
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09 Feb 2013 10:37 AM
Fair wrote:

We gave up on STX in our 2011 Mustang GT in late 2011, as it was never competitive no matter what tire brand or tricks we threw at it. Way too heavy for the class limit 265mm max width.

In STX trim we got it down to just under 3450 lbs (see above, with the temporary 18x10" wheel/275mm tire "STU" set-up, which worked a lot better than the 9" wheel/265mm tire. This was before the 2005-2013+ Mustang GT was locked into STX). Power was too easy to make... 430 whp with a cold air + headers, in STX legal trim. See the dyno below.

Power means nothing if you cannot use it. It was absolutely hopeLESS.

This car has no business being in STX, where it outweighs most cars in the class by 600 pounds or more. And yet it uses the same max tire width. In a word - F*CKED. It was more enjoyable in STU trim, but it will still lose badly there to 2900 pound EVOs (with almost the same power levels, but AWD, so it can actually use it)

Just my pessimistic two cents, about a stick axle heavyweight in a flyweight class. :) There isn't a place for 3200+ pound RWD cars in Street Touring, yet.

I have the same problem with my Mach 1. I can make power and I can even get into the 3300 lb arena but with 255 now being the biggest tire available for the class. It is really hard to get the car to turn or even go straight when I put the pedal to the floor. I even wrote up a thread about ST V8 only cars where tire sizes could be bigger, basically big cars big power minus corvettes(for obvious reasons) I was more or less told until a few fully prepped V8 cars got killed all the time no one would take the idea seriously.

I think ST classes should not have max tire sizes since we have a no fender change rule, whatever you can get inside of them with rolling should be the way it goes. Why is there a tire size rule anyway? I am a newbe so I have no clue how that rule came into effect. It only handicaps the larger cars which are already handicapped by weight anyway. I am building the car to "see" if I can be competitive this year but I have a feeling I will end up in ESP next year. At least the suspension rules are the same!

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