Pistons - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 10-19-2014, 10:06 PM   #21
Hug Life
iTrader: (3)
 
Monk's Avatar
 
Join Date: Apr 2014
Location: Huntington, Indiana
Posts: 2,804
Total Cats: 494
Default

Quote:
Originally Posted by sixshooter View Post
With 250whp in a very light chassis either transmission will last just fine.
I was thinking this as well, but OP seems to be the type to overbuild things ( not a bad thing).
Monk is offline   Reply With Quote
Old 10-19-2014, 10:40 PM   #22
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,370
Total Cats: 1,332
Default

Quote:
Originally Posted by BadGT View Post
actually thats very close to the truth
It's nowhere near the truth, actually. Built Quaife boxes start at about $2500 for used boxes and ~$4k+ for brand new boxes including case modifications, synchros, forks, etc. You also assume that a built 5-speed is stronger than a stock 6-speed, and those of us who are following the gearbox thread in the Race Prep section know that to be false at this point.

OTOH, 6-speeds can be had for $600-800 depending on mileage. In no world is a built 5-speed "cheaper" than a 6-speed. The OP's desired power level (250whp) is well within the reliable limits of a 6-speed, and your opinion about the gear ratios is not one that is shared by very many people, especially in a motorsport application.

Quote:
Originally Posted by BadGT View Post
loads of posts on miata.net agree with me
i lol'd IRL. M.net is not the place to be looking for advice on this sort of stuff

Last edited by Savington; 10-19-2014 at 10:53 PM.
Savington is offline   Reply With Quote
Old 10-19-2014, 10:59 PM   #23
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,198
Total Cats: 2,584
Default

Quote:
Originally Posted by BadGT View Post
actually thats very close to the truth and loads of posts on miata.net agree with me simply hit the google button.

btw FM used to have some very nice upgrades for the 5sp cant find them on their website any longer however.

Stop posting rudely just because you disagree with someone.
m.net you're joking right?....right?

HMM, I wonder why FM would discontinue something? lol

I was being polite in that post. I didn't even get rude yet

Simply put: your claims are plain wrong. Way off. Not even close. So please stop spreading misinformation.
18psi is offline   Reply With Quote
Old 10-20-2014, 12:32 AM   #24
Elite Member
iTrader: (2)
 
Mobius's Avatar
 
Join Date: May 2008
Location: Portland, Oregon
Posts: 3,178
Total Cats: 267
Default

Quote:
Originally Posted by BadGT View Post

Stop posting rudely just because you disagree with someone.
Nobody has been rude to you yet; you have actually been treated quite gently. You've been a member since June and you haven't figured out how this forum works yet?

You may not be in fact be a moron, but you are making factually incorrect, moronic statements. People that do so get banned quickly. Our moderators separate the wheat from the chaff and right now you're on the wrong side of that equation.
Mobius is offline   Reply With Quote
Old 10-20-2014, 01:46 AM   #25
Newb
 
Join Date: Jun 2014
Posts: 33
Total Cats: -14
Default

Let me explain my train of thought and clarify a few things

When i said i can get a few 5 speeds for the price of a 6 speed i meant a few normal non - built 5 speeds

also when i said cheaper i was referring to doing that as apposed to possibly breaking 1 or 2 6 speeds

(can get the by the truck load at pick and save )

I assume with any used transmission, not just those used for racing most people will go through it post purchase and at least inspect it.

Why not just upgrade with internals and feel good about it. (again personal preference i have yet to read the post savington spoke of)

I am the type to way over build for the future so i avoid doing it again if i would like more power.

I found out after asking a few people FM discontinued the 5 speed upgrade kit due to people having unrealistic ideas about how much power the upgraded 5 speed could handle and they got complaints (is not actually confirmed by anyone working for FM)

Quote:
You also assume that a built 5-speed is stronger than a stock 6-speed, and those of us who are following the gearbox thread in the Race Prep section know that to be false at this point.
Ill really have to read that thread after this im very interested. I helped a bit with the build up of a friends that is drag raced at our natural bridge track his has held up to hard launches for several years now. 1.8 @ 20~ psi does very well at our import night.

I also found out the photo i posted above was a 6 speed @ 272~ rwhp
Was used mainly for autocross


Yes i may prefer my methods and suggest them while others may suggest something else, that however does not mean i am attempting to mislead anyone just to be mean i am expressing my opinion based on my experiences. Which may or may not conform with what the masses consider standard.

Also i just preferred the 5 speed box, once again its a personal preference
BadGT is offline   Reply With Quote
Old 10-20-2014, 02:01 AM   #26
Junior Member
Thread Starter
 
paulw's Avatar
 
Join Date: Oct 2014
Location: Leeds,UK
Posts: 62
Total Cats: -6
Default

I'll stick with the 5 speed oem box and see what happens. In sprinting we are never on high revs for long. The circuits are very technical. In my vauxhall engined racer I locked 5th gear out. 6 gears will be useless unless there is significant proof of them being stronger.

I will build a stronger box when I see if the 5 speed is a week point.
paulw is offline   Reply With Quote
Old 10-20-2014, 02:02 AM   #27
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,198
Total Cats: 2,584
Default

Quote:
Originally Posted by BadGT View Post
Let me explain my train of thought and clarify a few things

When i said i can get a few 5 speeds for the price of a 6 speed i meant a few normal non - built 5 speeds

also when i said cheaper i was referring to doing that as apposed to possibly breaking 1 or 2 6 speeds

(can get the by the truck load at pick and save )

I assume with any used transmission, not just those used for racing most people will go through it post purchase and at least inspect it.

Why not just upgrade with internals and feel good about it. (again personal preference i have yet to read the post savington spoke of)

I am the type to way over build for the future so i avoid doing it again if i would like more power.

I found out after asking a few people FM discontinued the 5 speed upgrade kit due to people having unrealistic ideas about how much power the upgraded 5 speed could handle and they got complaints (is not actually confirmed by anyone working for FM)



Ill really have to read that thread after this im very interested. I helped a bit with the build up of a friends that is drag raced at our natural bridge track his has held up to hard launches for several years now. 1.8 @ 20~ psi does very well at our import night.

I also found out the photo i posted above was a 6 speed @ 272~ rwhp
Was used mainly for autocross


Yes i may prefer my methods and suggest them while others may suggest something else, that however does not mean i am attempting to mislead anyone just to be mean i am expressing my opinion based on my experiences. Which may or may not conform with what the masses consider standard.

Also i just preferred the 5 speed box, once again its a personal preference
You have a personal preference, cool, you're entitled to it, even if it may be extremely misguided and outside the norm. Tons of people do all sorts of weird things.

But that's a far cry from your original post, for which you got a bit of heat.

The gearing on the 6 is better for track. The 6 is significantly stronger. And when you say you can get a bunch of 5's for the price of one 6 you obviously don't consider the time or the effort swapping the trans. You're also ignoring the fact that there are a significant amount of broken built 5 speeds.

Search around, and you'll quickly realize why we have so many transmission discussions around here, and why everyone above 300whp is really itching for the "solution" that would work reliably and not break the bank. We've a lot of really long discussions about it here. And they are done by people making enough power and going fast enough on track to actually have something to say, not some m.net wine-n-cheezers or clubricer stancebroz
18psi is offline   Reply With Quote
Old 10-20-2014, 02:08 AM   #28
Newb
 
Join Date: Jun 2014
Posts: 33
Total Cats: -14
Default

Quote:
Originally Posted by 18psi View Post
You have a personal preference, cool, you're entitled to it, even if it may be extremely misguided and outside the norm. Tons of people do all sorts of weird things.

But that's a far cry from your original post, for which you got a bit of heat.

The gearing on the 6 is better for track. The 6 is significantly stronger. And when you say you can get a bunch of 5's for the price of one 6 you obviously don't consider the time or the effort swapping the trans. You're also ignoring the fact that there are a significant amount of broken built 5 speeds.

Search around, and you'll quickly realize why we have so many transmission discussions around here, and why everyone above 300whp is really itching for the "solution" that would work reliably and not break the bank. We've a lot of really long discussions about it here. And they are done by people making enough power and going fast enough on track to actually have something to say, not some m.net wine-n-cheezers or clubricer stancebroz


Ill agree i should have worded it better. Ill take caution to do so in the future cheers
BadGT is offline   Reply With Quote
Old 10-20-2014, 03:18 AM   #29
Elite Member
iTrader: (2)
 
Mobius's Avatar
 
Join Date: May 2008
Location: Portland, Oregon
Posts: 3,178
Total Cats: 267
Default

Well it will be interesting to see if the 5 speed survives for any length of time. If you really can get that chassis down to where it weighs less than Lewis Hamilton's underwear, maybe it will.
Mobius is offline   Reply With Quote
Old 10-20-2014, 12:45 PM   #30
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,370
Total Cats: 1,332
Default

Quote:
Originally Posted by paulw View Post
6 gears will be useless unless there is significant proof of them being stronger.
1. there is significant proof of 6-speeds being stronger
2. gear ratios don't work like you think they do
3. 6-speeds are faster
Savington is offline   Reply With Quote
Old 10-20-2014, 03:16 PM   #31
Newb
 
Join Date: Jun 2014
Posts: 33
Total Cats: -14
Default

Just leave this here for the OP

All below values based on tire size 205/50/15 yours may vary slightly
All below values are based on the final drive of 4.10

5 Speed manual 1990-12
gear ratio mph @7200 rpm
1st 3.163 38.1
2nd 1.888 63.8
3rd 1.333 90.4
4th 1.000 120.5
5th .814 148.1
6th NA NA
-- -- --
6 Speed Manual 1990-05
gear ratio mph @7200 rpm
1st 3.760 32.1
2nd 2.269 53.1
3rd 1.645 73.3
4th 1.257 95.9
5th 1.000 120.5
6th .843 143.0

Stock rear end ratios for North America
1990-93 5-speed 4.30
1994-97 5-speed 4.10
1999-05 5-speed 4.30
1999-03 6-speed 3.909
2004-05 6-speed 4.10
2006- all trans 4.10

Quote:
gear ratios dont work like you think they do
Ill attempt to explain as best as i can gear ratios and how they work for the op


Lets take a look at the 5 speed vs the 6 speed in 1st gear

5 speed

1st 3.163 38.1

6 speed

1st 3.760 32.1

now with the 5 speed the gear ratio is 3.163 this means for every 3.163 turns of the engine we are getting one turn at the rear end multiplying torque.

Now with the 6 speed its 3.760 so that means for every 3.760 turns of the engine we are getting 1 turn at the rear end

(the turns are actually measured at the output shaft of the trans i am just trying to make it easier to understand)

Now this means for several reasons the 6 speed is quicker

More torque multiplication and for turbo cars more time spent in the higher rpm range which is good for boost making more power.

Now you will find on almost every car forum or at any car meet guys arguing
I like the 6 speed its quicker i like the 5 speed its quicker!
This is because some people feel they would rather shift less and have a bit more room to use the boost they have made before shifting and having to start building boost again. The solution for this is almost always a upgraded head (valves, springs w/e) to allow you to safely rev higher.

Now lets look at the 4th gear of the 5 speed, and the 5th gear of the 6 speed.

These ratios are

5 speed 4th 1.000 120.5

6 speed 5th 1.000 120.5

notice the mph are the exact same? This is because its a 1:1 ratio meaning for everyone 1 turn of the engine (or transmission input shaft) you get 1 turn of the rear end (the output shaft)


Now lets look at the 5th gear of the 5 speed and 6th gear of the 6 speed

5 speed 5th .814 148.1
6 speed 6th .843 143.0

Now notice we have less than 1:1

The 5 speed 5th .814 148.1 meaning for every .814 turns of the engine (input shaft) we get 1 full turn of the rear end (output shaft) this is what is called an overdrive as the output shaft is spinning faster than the input shaft.


I hope i explained this properly and clearly.


adding some image below to help clarify the explanation.

Attached Thumbnails
Pistons-gr2a.gif  

Last edited by BadGT; 10-20-2014 at 03:53 PM.
BadGT is offline   Reply With Quote
Old 10-20-2014, 03:19 PM   #32
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,198
Total Cats: 2,584
Default

Don't forget though that the rear end fd changes those posted speeds quite a bit and the 5 and 6 come with different ones, not the same one

3.9 vs 4.3 is quite different
18psi is offline   Reply With Quote
Old 10-20-2014, 03:23 PM   #33
Newb
 
Join Date: Jun 2014
Posts: 33
Total Cats: -14
Default

Quote:
Originally Posted by 18psi View Post
Don't forget though that the rear end fd changes those posted speeds quite a bit and the 5 and 6 come with different ones, not the same one

3.9 vs 4.3 is quite different
Thanks cleaned up post to state that all values are based on the 4.10
BadGT is offline   Reply With Quote
Old 10-20-2014, 04:25 PM   #34
Junior Member
Thread Starter
 
paulw's Avatar
 
Join Date: Oct 2014
Location: Leeds,UK
Posts: 62
Total Cats: -6
Default

Bloody hell guys what have i started

I'll chuck a bit more fuel on the fire then because we run very soft Avon slick tyres in sprinting and hill climbing and the best choice of tyres is in 13" that is what i run could BadGT scale the ratio to suit? I run 7.5/20/13

So a six speed would fit?

Paul
paulw is offline   Reply With Quote
Old 10-20-2014, 04:37 PM   #35
Newb
 
Join Date: Jun 2014
Posts: 33
Total Cats: -14
Default

Quote:
Originally Posted by paulw View Post
Bloody hell guys what have i started

I'll chuck a bit more fuel on the fire then because we run very soft Avon slick tyres in sprinting and hill climbing and the best choice of tyres is in 13" that is what i run could BadGT scale the ratio to suit? I run 7.5/20/13

So a six speed would fit?

Paul
Sure i can to properly convert it would you like the 4.10 rear end conversations to i can accurately get you the values?

And yes the 6 speed is very easy to swap in out in my opinion
BadGT is offline   Reply With Quote
Old 10-20-2014, 04:39 PM   #36
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,198
Total Cats: 2,584
Default

I used to play with the gearing calculator FM has online for hours.

6sp+3.6fd=purrfect
18psi is offline   Reply With Quote
Old 10-20-2014, 04:41 PM   #37
Junior Member
Thread Starter
 
paulw's Avatar
 
Join Date: Oct 2014
Location: Leeds,UK
Posts: 62
Total Cats: -6
Default

Quote:
Originally Posted by BadGT View Post
Sure i can to properly convert it would you like the 4.10 rear end conversations to i can accurately get you the values?

And yes the 6 speed is very easy to swap in out in my opinion
That would be cool cheers

The 6 speeds are quite expensive over here.

Paul
paulw is offline   Reply With Quote
Old 10-20-2014, 04:42 PM   #38
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,198
Total Cats: 2,584
Default

18psi is offline   Reply With Quote
Old 10-20-2014, 04:47 PM   #39
Newb
 
Join Date: Jun 2014
Posts: 33
Total Cats: -14
Default

Quote:
Originally Posted by 18psi View Post
thats even better
BadGT is offline   Reply With Quote
Old 10-20-2014, 04:56 PM   #40
Senior Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Sweden
Posts: 1,391
Total Cats: 58
Default

Quote:
Originally Posted by paulw View Post
Bloody hell guys what have i started

I'll chuck a bit more fuel on the fire then because we run very soft Avon slick tyres in sprinting and hill climbing and the best choice of tyres is in 13" that is what i run could BadGT scale the ratio to suit? I run 7.5/20/13

So a six speed would fit?
6sp the same length as a 5sp, and the outer dimensions are not that much different either, swapping between then is easy.

Use a gear calc to find what total ratio you need at the fastest place for the hills/sprints you will run (rev and tire dependent).
Then use a 6sp and the highest final drive you can use. The higher you go in the gears the smaller the drop between gears.

In my case a 6sp with my 4.875 would be ideal (I don't need to go faster).

And there are 4.44, 4.77, 4.875 and 5.11 available beyond the Miata OEM list (which include 3.636 if you include EU and AUS markets).

Having two different rear ends to choose from would be vise, and better spend effort than doing anything more to a 6sp than changing oil. Even having OSG diffs in both may not change that judgement.
NiklasFalk is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 59 Yesterday 09:00 PM
OTS Bilstein to motorsports ASN conversion stoves Suspension, Brakes, Drivetrain 5 04-21-2016 04:00 PM
NEW-Wiseco Piston, K1 Rods, Supertech Valves & Spring/Retainer, TB&C pedals Rudes333 Miata parts for sale/trade 17 11-05-2015 02:16 PM
WTB Stock NB Pistons pdexta WTB 0 09-28-2015 12:18 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 08:42 PM.