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Greg G.

ST 5/6 (PT 5/6) Rules Proposal Thread--give your input here

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ILIKETODRIVE
Just like currently, I don't see much TTErs using A7 compound at 22pts in the lettered classes because the penalty isnt worth it, I'd much rather spend 22pts elsewhere.

Exactly why I hope slicks and A-tires get the heave-ho from PT6/TT6. No one will probably want to take that huge PTW adjustment anyways.

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JamesMilko

What is the reason that the HP calculation only looks at +- 2500rpm from max HP? Is there any reason why it shouldn't be the 3 highest intervals (500rpm spaced as is in the rule proposal) across the entire power band?

 

I think when looking at ST the problem isn't apparent since pushrod v8s only spin so fast. But I think this can be gamed when looking at smaller displacement motors with FI. Taking an example of a hypothetical Miata with a GT2554R and enough head/block work to spin to 8,500rpm. With the OEM transmission this car would not spend any meaningful time under 6,300RPM.

 

RPM HP

2000 50

2500 70

3000 75

3500 105

4000 134

4500 130

5000 130

5500 130

6000 130

6500 130

7000 170

7500 170

8000 170

8500 170

 

 

By the formula this would be a 131 avg HP car. Not saying it would be fun to drive or cheap to build, but I'm sure there are better examples. AP1 S2000s immediately come to mind. Closer gear ratios and higher stock red line.

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Greg G.
What is the reason that the HP calculation only looks at +- 2500rpm from max HP? Is there any reason why it shouldn't be the 3 highest intervals (500rpm spaced as is in the rule proposal) across the entire power band?

 

I think when looking at ST the problem isn't apparent since pushrod v8s only spin so fast. But I think this can be gamed when looking at smaller displacement motors with FI. Taking an example of a hypothetical Miata with a GT2554R and enough head/block work to spin to 8,500rpm. With the OEM transmission this car would not spend any meaningful time under 6,300RPM.

 

RPM HP

2000 50

2500 70

3000 75

3500 105

4000 134

4500 130

5000 130

5500 130

6000 130

6500 130

7000 170

7500 170

8000 170

8500 170

 

 

By the formula this would be a 131 avg HP car. Not saying it would be fun to drive or cheap to build, but I'm sure there are better examples. AP1 S2000s immediately come to mind. Closer gear ratios and higher stock red line.

170 +170 +170 +170 /4 = 170, not 131

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JamesMilko

Got a bit of tunnel vision there with the numbers, but the problem still does exist. These should be obtainable numbers with a small turbo on a BP. As long as it spools early it doesn't really matter what size turbo you use since you'll be blowing all the boost out to the atmosphere once you get past the RPM you need to trigger the max HP condition on the formula.

 

RPM HP

2000 50

2500 70

3000 75

3500 105

4000 145

4500 130

5000 130

5500 130

6000 130

6500 130

7000 140

7500 140

8000 140

8500 140

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RockLobster

At the very least any PT# class representing some hybrid between PT & ST but more like PT should ditch the engine and weight sections of the point system and require a reclass for all competitors or even better adjusted P:W using a basic website/smartphone calculator which would provide the adjusted P:W, factoring in area under the curve.

 

This is coming from someone who has never once run his car with a dyno reclass...

 

The other thought i have is instead of ditching the points system. Keep it, except for engine and weight, but assign each car an actual numerical value for base classing rather than the * system. Then have ranges of points for each class. This allows fine adjustments to specific models and trims without totally handicapping some special trims.

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Ev

I think it's safe to say that any rules package will have it's warts, PT does, ST does, all except the spec series suck, and even Spec series rules have issues.

 

If it was easy, someone would have already done it, and no one has.

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Salvisol

What are the problems with the current PT system? I've been doing HPDEs for a few years now. My target was to get into TTF/PTF. The current rules are easy enough to understand and I think the points system seems like a good concept. One of my reasons for picking PT instead of something like Spec Miata is that I don't want to have to pay crazy money in order to have a competitive car. The engine mods that I will need for my car to get to the power limit are not extensive, and will run me less than 1k. Most of my money will go to suspension, drive train parts, and consumables.

 

I've been buying parts and putting my plan together for the last few years. I really hope these new rules don't make my current plan and part purchases completely useless.

 

I might be ready for W2W by 2018. Whatever happens with the rules please make sure there is the possibility of good competition between the different cars and for sure make sure that people in the lower classes at least can still race on the cheap.

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RockLobster

Problems with the current PTB/TTB thru F system:

 

1. Enforcement

2. Enforcement

3. Complexity and thus accessibility

 

The system actually works very well on paper and if an army of tech inspectors were available for only PT/TT every weekend at every regional event, much less national event it would be great.

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RockLobster

I'd also vote to make PT5&6 strictly OEM aero (except vents and intakes). No aftermarkent wings, diffusers, side skirts, dams, splitters, canards, etc

 

I cant think of a single car that has meaningful down-force aero from the factory in the P:W realms of what would constitute PT5&6. There are some smooth underbodies these days for fuel economy improvements but i dont know that the benefits would be all that great. So, i dont think it would matter or give any car a significant advantage at all.

 

It would make TT5&6 more accessible and ultimately more competitive IMO.

 

Keep the "no-points" mods in all cases.

 

Find a good system of P:W adjustment that is even more comprehensive than TT/ST 3 & 4.

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Mrsideways

Here is the issue, There needs to be a better adjustment for weight.

 

Take a 2000lbs car that's 200 hp (10:1) and start accelerating at 140 mph.

Now take the same car (for aero reasons)

Add 100 hp and 1000lbs and start accelerating at 140 mph. The heavier car will win..... by a lot.

 

Because lets say it takes 200hp to push that car though the air at 140mph. Weight doesn't matter the 200hp car won't move, But the 3000lbs car has a 100hp to help it move forward.

 

Yes the Heavier car also has make that extra 1000lbs stop and turn. But with as good as big tires are these days, weight is less of an issue. Because in a racing situation, the light slow car might get through the corner quicker, but then the heavy car gets the advantage of the draft and the peak mph to make the pass a lot easier. Besides as my friends who run GTR's on the one lap joke "The weight is just free downforce at low speed". And the more aero you throw at the ligther car the more the highspeed is going to hurt it. Where as the heavy car can toss the aero on with a much lower disadvantage at speed. But look at the one lap of america, a GTR wins it nearly every year at 4000lbs on street tires. In order for something other then a GTR to win that event in the near future they are going to have to start allowing stickier tires.

 

As for the avg. I'd like to see more then 3 data plots used for the avg. But that's just me. Even with my relatively close gearing I'll drop below my lowest data point for the average on track regularly. But thats because it's higher revving engine. a diesel would be fine with 3 data points. Perhaps the amount of data points needs to be based on how high the thing revs.

The Idea I had was use the Max RPM as the basis for how often your data points are. So a 8000 rpm motor pulls a data point every 800 and a 5000 rpm motor would pull it every 500.

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sellier

The Idea I had was use the Max RPM as the basis for how often your data points are. So a 8000 rpm motor pulls a data point every 800 and a 5000 rpm motor would pull it every 500.

This sounds like a great idea. Are there any downsides to doing this other than the "complexity" as this would certainly make things fair regardless of where you engine revs to.

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ndogg

The Idea I had was use the Max RPM as the basis for how often your data points are. So a 8000 rpm motor pulls a data point every 800 and a 5000 rpm motor would pull it every 500.

This sounds like a great idea. Are there any downsides to doing this other than the "complexity" as this would certainly make things fair regardless of where you engine revs to.

 

I concur with this. As its written now the rule is supposed to "help" the high reving peaky engines. But the higher you rev, the broader the RPM range that is used.

 

Also, I disagree with only allowing oem aero. There is going to be cost to build a race car, you can get some pretty functional aero for pretty cheap these days. I'd rather spend $900 on a wing and make a DIY splitter. Feel free to skip the aero and you get extra power to make up for it.

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Mrsideways

I'll be honest I screwed up and put this in the ST5 discussion. This should apply to 3, 4 and 5

 

Also the OE aero thing is kinda interesting cause some cars have crazy good oem aero.... And those cars happen to be some of the fastest in each class. 911 GT3 comes to mind. GT4 comes to mind. Viper comes to mind.

 

Should Limit Aero to Wing and modest splitter. Start giving aero mod factor for canards, under body and different bumpers and such. Lots of time to be had from playing with the under body. Allow aero under the car from center line of axles to the front bumper and to the rear axle to the rear bumper.

 

Also mod factor for increasing track width. You can make some serious time from widening a car and that's completely legal right now.

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RockLobster

To be clear i'm only advocating strictly OEM areo for PT/TT 5/6. You really will not see substantially effective aero from the factory on any car that can slot into what is currently PTF, E, & D. I can't think of a single one. Are they all different aerodynamically? Yes. The point is none of it is designed to create downforce or even appreciably limit lift. It's all for aesthetics and fuel mileage. 911 GT3 need not apply.

 

I dont think anyone would argue that a heavier higher HP car vs lighter/lower in the same class will have an advantge in a W2W race at MOST tracks. But in TT i think the system actually is pretty balanced for simply nailing a lap time. That's the crux of the problem. The P:W rules and adjustments i think work pretty well for TT but for W2W racing lighter is a handicap.

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ndogg

Yes probably not many TT5/TT6 cars going to have great oem aero. That's still no reason to ban aftermarket aero for those classes. I like Mr Sideways idea of separate mod factors for each piece of aero. That keeps anyone with lots of money going totally crazy on aero, but allows simple wings / splitters.

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RockLobster

Yeah, the reasons are many though. Makes the higher W:P ratio (ST5/6) more accessible and easier to police, and cheaper to run. I think there should be a home where people don't have to worry about or even consider aero and if they are buying/building something effective or only marginally so vs competitors. Plus in all honesty the home built aero often looks well......home built, and brings a definite air of amateur to the series compared to other classes. Especially the giant air dams made from sheet plastic, etc. I think you would have much more participation if the 5/6 classes had OEM only aero.

 

For those that have to have aero to play, go play in ST 1,2,3, or 4.

 

The whole point of this is to make it easier to enforce and understand and make it more accessible to folks. So, making it any more complex than a single modification factor for non-oem aero in 3 and 4 is too much a sideways move.

 

ST 1/2 Open Aero

ST 3/4 Modification Factor for anything non-OEM

ST 5/6 OEM ONLY

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ndogg

If you want a competitive car in a class, you aren't just going to roll in off the street and throw down because it doesn't allow aero. It takes time and work and money to get that. Whats the difference if you spend the money on HP, spend it on weight reduction, spend it on 5k shocks, or spend it on aero.

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jpreston
Whats the difference if you spend the money on HP, spend it on weight reduction, spend it on 5k shocks, or spend it on aero.

 

Agreed. If ST 5 and 6 become OEM aero only, I'll probably move to Spec Miata. Most of the guys that are currently running aero miatas in PTE are in PT because the aero makes the car faster and so much more fun to drive than a spec miata. Take away the aero and there's not near as much reason for us to stay in PT/ST. A pro-built SM motor is cheaper than aero, a standalone ECU and tuning, and a good set of PT-legal shocks. ST4 power levels in a miata requires an engine swap or boost, which I (and probably a lot of other guys) have no interest in because of cost and reliability.

 

7 months later, I still fully stand behind my post back on page 5. The only thing I've thought about since then that I'd like to see change is to remove all mod points for chassis stiffening and reinforcement, except maybe the one about the cage going through the firewall. I've always thought it was silly that we allow caged cars to run against non-caged cars in TT, but the non-caged cars get penalized for any chassis stiffening modifications. And as someone who has been behind the wheel of a bone stock E36 M3 when the trailing arm mounts ripped out of the chassis while driving home from work at 30mph through a neighborhood, I also think cars like the E36 and E46 should be able to fix major safety issues without taking modification points.

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J.R. Smith

Yeah, the reasons are many though. Makes the higher W:P ratio (ST5/6) more accessible and easier to police, and cheaper to run. I think there should be a home where people don't have to worry about or even consider aero and if they are buying/building something effective or only marginally so vs competitors. Plus in all honesty the home built aero often looks well......home built, and brings a definite air of amateur to the series compared to other classes. Especially the giant air dams made from sheet plastic, etc. I think you would have much more participation if the 5/6 classes had OEM only aero.

 

For those that have to have aero to play, go play in ST 1,2,3, or 4.

 

The whole point of this is to make it easier to enforce and understand and make it more accessible to folks. So, making it any more complex than a single modification factor for non-oem aero in 3 and 4 is too much a sideways move.

 

ST 1/2 Open Aero

ST 3/4 Modification Factor for anything non-OEM

ST 5/6 OEM ONLY

 

Nice and simple - I like it.

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flier129

Any updates on ST5/6 being implemented in 2017 or is it a definite 2018 time-frame?

 

 

My main concern with the current TTB-F rule-set.... 0-point engine builds. Why is it legal with no penalty, in a low-cost class, to build a ~$4000 engine that will make 10-15 more hp than my un-opened engine? Where as I get hit with points if I want to add a $300 intake manifold and $700 ecu to see similar gains? Yes, yes I know "just do a dyno-reclass!", but I'm talking about the down-falls of the current rule-set.

 

 

On another note, I think 1pt = 0.14 lb/hp would ultimately lower the ceiling on how fast ST5/ST6 could go, but not necessarily lower the costs of them(see concern above, lol). Though, something along those lines could work, but I'll be sad if I see the new classes end up being slower than the old.

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ndogg
Yeah, the reasons are many though. Makes the higher W:P ratio (ST5/6) more accessible and easier to police, and cheaper to run. I think there should be a home where people don't have to worry about or even consider aero and if they are buying/building something effective or only marginally so vs competitors. Plus in all honesty the home built aero often looks well......home built, and brings a definite air of amateur to the series compared to other classes. Especially the giant air dams made from sheet plastic, etc. I think you would have much more participation if the 5/6 classes had OEM only aero.

 

For those that have to have aero to play, go play in ST 1,2,3, or 4.

 

The whole point of this is to make it easier to enforce and understand and make it more accessible to folks. So, making it any more complex than a single modification factor for non-oem aero in 3 and 4 is too much a sideways move.

 

ST 1/2 Open Aero

ST 3/4 Modification Factor for anything non-OEM

ST 5/6 OEM ONLY

 

Nice and simple - I like it.

 

So you are basically telling anyone that doesn't drive a high HP car, that they can't use aero. I don't agree with that. If you don't want aero, then add the extra HP to make up for it. Simple rules don't necessarily make a good class. Good rules do.

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takjak2

While I agree that some aero should be allowed for ST 5/6 the problem is balancing the rules so it doesn't become a requirement. I can tell you that the 0.4 factor in TT3 was never balanced.

 

In order to prevent aero from becoming a huge sink in development time and $$, good rules have to present a limit. Balancing and enforcing those rules is no easy task. So where can we draw the lines?

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RockLobster

Exactly my point. You cant. So anyone with cubic dollars can beat up those on a budget in a class with open aero or an aero mod factor. Further, prescriptive stuff to me never works because they affect the performance of different makes and models differently. A prescriptive air dam on one car may offer more benefit than on another car. This has been proven in SCCA many times over.

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RockLobster

How about we just adjust the mod factor then.

 

OEM Aero +1.5

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ndogg
Exactly my point. You cant. So anyone with cubic dollars can beat up those on a budget in a class with open aero or an aero mod factor. Further, prescriptive stuff to me never works because they affect the performance of different makes and models differently. A prescriptive air dam on one car may offer more benefit than on another car. This has been proven in SCCA many times over.

 

Lol. It's been well regulated in the letter classes for a while now.

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