4th gen ND Mazda MX-5 Miata

[nikitopo]

Originally Posted by mrg666

240 hp? Give me a break, please. You keep repeating these power gain claims. How hard it is to go get a dyno and provide proof? 2017 model got only 5hp extra with several other changes combined in addition to header. We don't even know if header itself is making any change by itself. Either provide the proof or just keep posting and I will keep calling this .

I am getting ~26% better acceleration comparing to stock. It is known that acceleration is proportional to force. If you rate the first cars as 190bhp, then it feels like a 240bhp stock car. For me it doesn't make sense to make a dyno because some changes will not appear there. However, what it counts is what you have in reality and not just a plain number. So, acceleration figures are more important to me.

[why?]

Originally Posted by fatoni

Google what Los Angeles looked like before things like carb and Google how much hp the mustang had before that damned fuel injection became mandated. Not saying there aren't better ways but to say nothing comes from regulation is simply wrong.

Sorry but that has nothing to do with cars. It has everything to do with factories. The cost of the filters that they need to use now is insane. However that insane cost keeps air clean. Regulation has its place, sometimes it is needed to slap idiots around. Why you think regulation created decades ago still has a use today is the issue. What was good 40+ years ago just hurts everything modern.

Originally Posted by wbradley

Some people are so far to the right that they think everyone should have their very own country. So the private sector will fix things when it goes back to this?
Please...

Why would it go back to this? What else from the early 80's is still in use? If nothing else from the early 80's is worth using, maybe we also need to evolve regulation and car technology. There is still zero proof smog is from vehicles, and not from actual factories, you know the things that actually throw massive amounts of smoke into the sky and now have to spend tens of thousands on filters and the like to clean that air.

Originally Posted by mav1178

So what is a modern technology that is better and less costly than a catalytic converter to reduce NOx and CO emissions out of a car?

We have modern day gas vehicles that actually put out air cleaner than what they take in. Volvo especially was having fun advertising that fact. If we can do that, why do you think we cannot come up with something better? A carb is tech from the early 80's. Not much else from then is in common use today for a reason.

Originally Posted by NoHaveMSG

Ever see what the inside of a modern big rig exhaust looks like? Freightliner drove one from Mt Holly, NC to OR to show the company my father just retired from, the exhaust tips were clean. Since he started there from the time he retired truck fuel mileage also nearly doubled.

Yes and that is great. And that can easily happen without onerous government regulations for tech that is almost 40 years old. Also note that bigs rigs have very little in common with cars. Cleaner is always better. The people making the vehicles are better at figuring out how to make them better than a clueless moron bureaucrat could ever be.

[funwheeldrive]

Originally Posted by nikitopo

I am getting ~26% better acceleration comparing to stock. It is known that acceleration is proportional to force. If you rate the first cars as 190bhp, then it feels like a 240bhp stock car. For me it doesn't make sense to make a dyno because some changes will not appear there. However, what it counts is what you have in reality and not just a plain number. So, acceleration figures are more important to me.

Assuming the original models made 190 at the crank, and the revision makes 205 at the crank, thats still 35hp to make up for. What "other things" do you have done? I can't imagine you have more than 100lbs shed from the car right?

Do you have better tires? Wouldn't that account for a lot of the acceleration differences you are talking about?

[Tcoat]

Originally Posted by nikitopo

I am getting ~26% better acceleration comparing to stock. It is known that acceleration is proportional to force. If you rate the first cars as 190bhp, then it feels like a 240bhp stock car. For me it doesn't make sense to make a dyno because some changes will not appear there. However, what it counts is what you have in reality and not just a plain number. So, acceleration figures are more important to me.

How did you measure this?

[nikitopo]

Originally Posted by funwheeldrive

Assuming the original models made 190 at the crank, and the revision makes 205 at the crank, thats still 35hp to make up for. What "other things" do you have done? I can't imagine you have more than 100lbs shed from the car right?

Weight of car is ~2620 lbs.

I didn't measure all the before and after changes, so I cannot tell which one gave the most. My last change was a lightweight flywheel change which gave a 6% gain in a 2nd gear pull. Details here:

http://www.ft86club.com/forums/showp...7&postcount=74

[ZDan]

Originally Posted by funwheeldrive

Assuming the original models made 190 at the crank, and the revision makes 205 at the crank, thats still 35hp to make up for.

But even +15hp for '17+ seems very optimistic to me. Mag tests showed about a tenth of a second improvement in 0-16 and 1/4-mile which could be attributed to diff ratio change from 4.1 to 4.3. 1/4-mile trap speed unchanged, which suggests no additional power. Or only enough to offset a slight weight gain.

[nikitopo]

Originally Posted by ZDan

But even +15hp for '17+ seems very optimistic to me. Mag tests showed about a tenth of a second improvement in 0-16 and 1/4-mile which could be attributed to diff ratio change from 4.1 to 4.3. 1/4-mile trap speed unchanged, which suggests no additional power. Or only enough to offset a slight weight gain.

I believe the '17+ cars were also heavier. It looks they added some extra reinforcements to pass newer crash tests in US and Canada. Check here:



In other regions same trim levels were ~20kg lighter.

And a 4.3 fd doesn't mean that will make you EVERYWHERE faster. In certain tests it can give worse results comparing to a 4.1 fd. It depends the test.

[ZDan]

Originally Posted by nikitopo

I believe the '17+ cars were also heavier.

Yeah, about 50 lb. But it's not enough to allow for '17+ cars having +15 more hp, more like the advertised +5hp
Power/weight with driver:
pre-'17 (2770 lb. + 170 lb.)/200hp = 14.7 lb/hp
'17+ PP (2820 lb. + 170 lb.)/205hp = 14.6 lb/hp

And a 4.3 fd doesn't mean that will make you EVERYWHERE faster. In certain tests it can give worse results comparing to a 4.1 fd. It depends the test.

Fully aware of this, but for 0-60 both the 4.3 and 4.1 diff require a shift to 3rd gear, and for 1/4-mile both do it in 4th, so specifically for those tests, 4.3 should be a slight advantage. Looks like about a tenth...

0-57mph, 4.1 would have a HUGE advantage, on the order of 1/2 a second, due to no 2-3 upshift. But that's not the case here.

[WolfpackS2k]

Originally Posted by nikitopo

It depends if you want to cheat or not. If not they'll just fail the test. Why do you think they put a piece of metal if it was not absolutely necessary? A catless header should be for racing use ONLY. Everything else is about pretending to be ethical and not obeying the laws. And of course we are also pretending that we are car enthusiasts by removing just a cat. Why don't we do other things like buying the new factory header, doing weight reduction or in general try other approaches that don't have any impact on the regulations? Because it is not that easy or it is more expensive? Then we are not really car enthusiasts. And I don't buy the argument that it is OK a 5% or less of enthusiasts to go catless, because there is not so much impact. It is like sticking the finger to the rest of the people out their who obey the laws and respect the others.

Just because you removed an exhaust manifold with integral catalytic converter doesn't mean you're running a catless exhaust. Doesn't the BRZ have 3 catalytic converters? Sure it's illegal to remove cats, but at least here in NC you can pass annual emissions testing as long as there is at least one cat in the exhaust. And one cat, believe it or not, actually cleans the exhaust up pretty well.

If you want to cry about exhaust emissions, point your ire towards the soot emitted by direct injection gasoline engines. Which is considerably worse for the environment, and yet also legal.

[mav1178]

Originally Posted by why?

We have modern day gas vehicles that actually put out air cleaner than what they take in. Volvo especially was having fun advertising that fact. If we can do that, why do you think we cannot come up with something better? A carb is tech from the early 80's. Not much else from then is in common use today for a reason.

Yes, but how many of these are without a catalytic converter?

A catalytic converter is still vital to reduce CO and NOx emissions. There's no other solution out there that is as simple and as cost effective.

[nikitopo]

Originally Posted by ZDan

Yeah, about 50 lb. But it's not enough to allow for '17+ cars having +15 more hp, more like the advertised +5hp
Power/weight with driver:
pre-'17 (2770 lb. + 170 lb.)/200hp = 14.7 lb/hp
'17+ PP (2820 lb. + 170 lb.)/205hp = 14.6 lb/hp

Fully aware of this, but for 0-60 both the 4.3 and 4.1 diff require a shift to 3rd gear, and for 1/4-mile both do it in 4th, so specifically for those tests, 4.3 should be a slight advantage. Looks like about a tenth...

0-57mph, 4.1 would have a HUGE advantage, on the order of 1/2 a second, due to no 2-3 upshift. But that's not the case here.

You are correct.

It depends also WHEN the tests were performed. Check a dyno test of a stock '17 BRZ here:
http://www.ft86club.com/forums/showp...28&postcount=1

On first run the AFR is similar to an aftermarket tune. On second run it starts adding fuel, the AFR is getting similar with pre-'17 cars and it loses power. This is also the reason why we never agreed in the forum if the actual gain was +5hp or +15hp. I mean apart from catalog numbers.

[ZDan]

Originally Posted by nikitopo

It depends also WHEN the tests were performed. Check a dyno test of a stock '17 BRZ here:.

I wouldn't compare dyno vs. dyno results unless testing a '17+ vs. '16-, both totally stock, on the same dyno the same day. And even then it wouldn't be enough to conclusively nail it down.

Fact is, 2017+ cars are testing at the same 1/4-mile trap speeds vs the previous cars, and lo the weight difference between non-PP Limiteds isn't all that much after all, 2764 lb. for 2013 and 2777 lb. for 2017:
https://www.caranddriver.com/reviews...ed-test-review
https://www.caranddriver.com/reviews...al-test-review

1 tenth quicker, 0mph faster in the 1/4 at the same weight.

I don't think the 17+ are making much if any more real-world usable power.

[mrg666]

Originally Posted by nikitopo

Weight of car is ~2620 lbs.

I didn't measure all the before and after changes, so I cannot tell which one gave the most. My last change was a lightweight flywheel change which gave a 6% gain in a 2nd gear pull. Details here:

http://www.ft86club.com/forums/showp...7&postcount=74

I don't believe your engine mods made any significant changes in power. There is no proof. Looking at your build thread they are just expensive nonsense. If you really saved 200 pounds, which I don't believe either, the acceleration difference cannot be better than 7% (200/2800*100) using f=ma equation. Keep posting but I will be ignoring all your posts from now on.

[nikitopo]

Originally Posted by ZDan

I wouldn't compare dyno vs. dyno results unless testing a '17+ vs. '16-, both totally stock, on the same dyno the same day. And even then it wouldn't be enough to conclusively nail it down.

Fact is, 2017+ cars are testing at the same 1/4-mile trap speeds vs the previous cars, and lo the weight difference between non-PP Limiteds isn't all that much after all, 2764 lb. for 2013 and 2777 lb. for 2017:
https://www.caranddriver.com/reviews...ed-test-review
https://www.caranddriver.com/reviews...al-test-review

1 tenth quicker, 0mph faster in the 1/4 at the same weight.

I don't think the 17+ are making much if any more real-world usable power.

You know that 0-60 , 1/4-mile and the rest of the measurements are not very accurate. Right? They involve a car launch. Especially on a MT car you can have big differences. There is a reason why I made my acceleration measurements with a rolling speed and using 2nd gear.

The result of the dyno cannot be ignored. You can argue all day about the accuracy of a dyno, but you cannot ignore the fact that the '17+ cars have better AFR's, BUT not constantly. After a point they will add fuel and lose power and in this case I agree the difference between an old and a new car is smaller. However, when the AFR is better you have much better engine output. If you don't know it, then ask whatever tuner you like.