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y8s 01-31-2017 11:48 AM


Originally Posted by Godless Commie (Post 1389659)
Matt, no.

A downhill skier does not accelerate at 1 G. Their acceleration would be a function of G, the angle of the slope and wind resistance + friction.
It's not freefall in a vacuum.
And acceleration is not constant.

There are many tracks with tight turns and short straights where a car would not be able to exceed 100 mph, so that is not a deal breaker.
Besides, I was asking about whether or not a car and a skier would follow identical lines through identical turns.
Speeds could be different, but that does not mean lines should be.

You'd be surprised how much braking skis are capable of.
I'd be willing to bet a skilled skier would be able to outbreak a lot of cars at sane speeds.
Skis also turn quicker than a car.

And, a pair of downhill skis are nothing like rock hard tires.
You can generate pretty impressive lateral G forces on a decent pair of skis.
Yes, you can slide if you like, and that really bleeds off speed in a hurry.
If your boots are cant-adjustable, or if you have perfect stance (I do) you can maintain a lot of speed when you need to.

----

I was watching men's downhill races and started paying attention to all the different lines the racers were using.
That got me thinking.
Inevitably, those who turn in early and get an early apex are faster overall.

I misread your original post. And yes, I know skis can lock into a groove and maintain serious lateral G. You're right about acceleration, there's a vector diagram in there reducing the maximum acceleration.

Cars can also slow down considerably without brakes. My dad once told me a story of his race days when he lost his brakes and continued to race since he was in a good position. They eventually black flagged him though, because he was scrubbing speed by doing 360s to slow down for tight corners.

Dad loved telling stories.

Godless Commie 02-01-2017 07:13 PM

It's just no fun riding a 432 lb bike on icy roads. At night.
I made home in one piece, and without dropping the bike, but I have somehow mastered turning with zero lean.

Hadn't realized the temp had dipped below freezing, and a lot of road surface is wet, jut waiting to turn into nasty.

Godless Commie 02-01-2017 07:20 PM

İn completely unrelated news, I may be going to Bansko, Bulgaria for a week of skiing to celebrate my right knee's first birthday.

This week marks the first anniversary of reconstructive surgery on my knee.
Ligaments, ACL, fracture, meniscus, the works.

Couple hundred Euros + lift tickets and incidentals for 7 days and 5 nights.
Not a bad deal.

G3ML1NGZ 02-01-2017 07:43 PM

"my knee is good now. Let's fuck it up" ;)

bahurd 02-01-2017 07:59 PM


Originally Posted by Godless Commie (Post 1390125)
İn completely unrelated news, I may be going to Bansko, Bulgaria for a week of skiing to celebrate my right knee's first birthday.

This week marks the first anniversary of reconstructive surgery on my knee.
Ligaments, ACL, fracture, meniscus, the works.

Couple hundred Euros + lift tickets and incidentals for 7 days and 5 nights.
Not a bad deal.

Good luck. Remember, weight centered with pressure on the outside ski and whatever you do... get the hell out of the way if there's a Miata gaining on you.

Godless Commie 02-01-2017 09:35 PM


Originally Posted by G3ML1NGZ (Post 1390132)
"my knee is good now. Let's fuck it up" ;)

Not necessarily.
I had emergency back surgery in late 06, and I was skiing exactly 21 days later.
That is how I get back into my "regular life". I need to know that I can do the things I enjoy after a traumatic event.

I also happen to be a pretty accomplished skier - just a little over 30 years on the slopes.
I used to average 45 days a season back in the day.

Erat 02-01-2017 10:49 PM

Talking to some fellow boat builders regarding their engine and setup today.
I ask about how they are overcoming the challenge of tuning their engines; when typically you get one maybe two test sessions which is 3 miles per. I got a simple no hesitation answer, "read the plugs". Which was confirmed by two other people standing in on the conversation.
Not wanting to sound like a fool, i didn't ask him / them to elaborate.

I come home, find this:
Spark Plug Reading 101 by Mike Canter - Dragstuff

This has to be a joke, right? In 2017, we're still tuning engines this way? So you mean to tell me, that you need to go out, burn up a test session. Come back, read plugs, make blind adjustment on carburetor and hope you can get a second test session in to see if the changes were beneficial. Having only ever tuned using a computer to tune, this in my mind is an absolutely absurd and inefficient way of doing this. Not to mention using ones personal opinion / best judgement on the matter. Nothing like blindly changing things with no scientific data. Unless you have 40 years of "plug reading" under your belt, i don't think i (personally) should be doing this.

Or am i just an idiot and really it's just that simple?

Edit* if someone could send me a youtube video or good literature regarding initial spark plug reading, tuning the carb via the findings, and then an after analysis "plug reading" to verify suitable changes have been made i'd appreciate it.

EO2K 02-01-2017 11:12 PM

It is and it is not that simple, that's the problem.

A lot of these guys tune by smell, or by feel, or by pitch, or by 60' time because they have no other reliable source of data other than a vacuum gauge and like you say, 40 years of experience. Sometimes they remain willfully ignorant because they just don't want to learn another way of doing things. CAN they get other data? Sure! Innovate Motorsports has the LM-1 and LM-2 wideband dataloggers that were perfect for this stuff, and they've been available for decades. But remember, these are guys who barely understand why they have to reset mechanical dwell on a points distributor when they advance timing, why would they ever want to understand a wideband output or deal with, horror of horrors, a computer datalog? If it bogs off the line, go one step smaller on the accelerator pump nozzle and see if you can stretch out the shot. If she knocks under load, step it up a size on the primary jets to drown the knock with fuel, or spin the distributor back a couple degrees. It all makes sense to these guys because they've done this for so long they can do it by feel.

I deal with this shit all the time at work, because I work for a multi generational farming company. The old guys who have been growing shit in the ground the same way for the last 300 years don't understand the point of direct monitoring/logging things like temperature, rainfall, actual water content of the soil at different depths, evapotranspiration losses, or even soil content. I've literally stood in a field and watched a guy smell the dirt and then make a fertilizer recommendation. He learned how to do that from his father, who learned from his father, who learned from his father before him. Why does he need a computer to grow crops?

The trick is that he does not, and he is right, we've been growing shit in the ground for thousands of years. What they fail to realize is that by leveraging the data we can save money by increasing efficiency and decreasing operating costs. They don't understand how historical trend data and meticulous record keeping will allow you to anticipate growing conditions and yields before the plants even come out of the ground. The old guys don't want to deal with it, but the younger generation who all went to CalPoly and have computer and ag science backgrounds understand this stuff. They understand that you've got to work smarter, not harder, if we expect to continue to feed the ever expanding mass of humanity with the limited resources available. We keep making more people, but we sure as hell are not making more ag land.

So yes, there are better ways to do it, but you've gotta wait for all the old guys to die off before anyone takes it seriously.

/rant

aidandj 02-02-2017 01:34 AM

Skip the plug reading and get an LM-2. Or a megasquirt. Or any real data logging.

Erat 02-02-2017 05:20 AM

I don't see anywhere in the rules that say you can not data log.
​​​​​​Maybe if I do it they will create a rule just for me.

Edit*
They also tell me that in any given season they will need to do 2-3 rebuilds. It makes sense now.

sixshooter 02-02-2017 07:42 AM

Not casting aspersions or anything, but a certain Miata drag racer on this forum has a carbureted setup and no O2 monitoring. When I went to the drag strip to watch him run he was determining he needed to richen or lean out the full throttle mixture by a combination of perceived feel and throwing a handful of SAE wrenches in a hubcap and reading how they landed. No plugs were pulled in the process.

As a heathen, I still am in unbelief of the efficacy of the process. And to his credit that drag racer intends to use a wideband to tune his carburetors in the next iteration of his build. And he is considering fuel injection in a couple of years.

fooger03 02-02-2017 07:46 AM

What are you racing in?

Erat 02-02-2017 07:53 AM


Originally Posted by fooger03 (Post 1390212)
What are you racing in?

5 liter hydroplane.

TurboTim 02-02-2017 08:13 AM

There's a dyno cell where I work, we rent it out. In the 11 years I've been here, the WBO2's haven't come out of their drawer. These engines tend to be worth a few times more than my gross annual salary, and the builders/tuners are paid many monies to do it. Some of these guys are scary.

Further proof that most experts in life are just good at marketing themselves, and if you want something done right, do it yourself.


Originally Posted by Erat (Post 1390214)
5 liter hydroplane.

VP Manufacturing is running a 2.5 Liter Stock Hydro this year. It looks like a fun boat.

Joe Perez 02-02-2017 08:19 AM


Originally Posted by sixshooter (Post 1390210)
...and throwing a handful of SAE wrenches in a hubcap and reading how they landed.

:bowrofl:

It's true, of course. Lots of engines got built and tuned before the invention of the wideband O2 sensor, or any O2 sensor for that matter. And lots of guys grew up doing it that way, and got good at it.

Those of us who came of age during the transition into EFI got comfortable with it, and never learned the secrets of the Old Ones.

TurboTim 02-02-2017 08:48 AM


Originally Posted by Joe Perez (Post 1390220)
:bowrofl:

It's true, of course. Lots of engines got built and tuned before the invention of the wideband O2 sensor, or any O2 sensor for that matter. And lots of guys grew up doing it that way, and got good at it.

Those of us who came of age during the transition into EFI got comfortable with it, and never learned the secrets of the Old Ones.

Reading plugs is how I tune the carbs on my 2 strokes.

I suck at it, but my dad is good. Thank god.

http://www.absurdflow.com/challenger/challenger27.jpg

Erat 02-02-2017 09:11 AM


Originally Posted by TurboTim (Post 1390219)
There's a dyno cell where I work, we rent it out. In the 11 years I've been here, the WBO2's haven't come out of their drawer. These engines tend to be worth a few times more than my gross annual salary, and the builders/tuners are paid many monies to do it. Some of these guys are scary.

Further proof that most experts in life are just good at marketing themselves, and if you want something done right, do it yourself.


VP Manufacturing is running a 2.5 Liter Stock Hydro this year. It looks like a fun boat.

I want to say 2.5 and 2.5 mod run in the same class as 5 liter. But do not compete against each other for national points.

I hope someone on the team is good at reading plugs and tuning carburetors with such techniques. Because if I do it im sure it won't be right.

hi_im_sean 02-02-2017 09:29 AM

Then there are 2 stroke dirtbikes, that not only wont support any sort of o2, but would be a waste of time. I mean, I guess you can temporarily rig up a 12V battery, or maybe spend $300 on a stator kit if they make one for your bike. I can do 5 plug chops and associated carb adjustments in 20 minutes and be jetted right. I think its a matter of platform. Will I do plug readings on my MS equipped Miata? never (except maybe when severe, drawing straws troubleshooting madness occurs)

The first mass produced 2 stroke dirtbike comes out in 18'. They will get my money immediately. I don't like doing plug chops, but on certain vehicles it makes sense.

bahurd 02-02-2017 10:39 AM


Originally Posted by TurboTim (Post 1390227)
Reading plugs is how I tune the carbs on my 2 strokes.

I suck at it, but my dad is good. Thank god.

Same when I raced Kawasaki H1 & H2 bikes. The middle cylinder was the bitch.

y8s 02-02-2017 11:38 AM

the next generation of tuners will look at us and laugh about how we used distillates of petroleum from random sources to make fire in side our engines happen earlier or later as "tuning"

And they will hand us a laptop and say "here is my motor's precise power output at all possible atmospheric and road conditions, yaw angles, and sun spot activity tied to GPS coordinates of the car"


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