Street Car with 3071R : 5 speed with 3.9 OK? - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Suspension, Brakes, Drivetrain discuss the wondrous effects of boost and your miata...

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 10-20-2015, 09:39 PM   #1
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2005
Location: Los Gatos, California
Posts: 67
Total Cats: -4
Default Street Car with 3071R : 5 speed with 3.9 OK?

Trying to figure if the original 57K miles 5 speed will be fine on the street with built 1.8 and 3071R turbo?
About 320whp DJ.
Gentle on transmission and clutch, no drag racing, no full throttle shifts, no 30 minute racing.

I know racers break 5 speeds, and 6 speeds, and it seem to be related to both- loss of lubrication of the gears and thermal overload weakening material: racing without oil cooler causes miniscule amount of gearbox (and diff) oil to get real hot, to the point of not providing nor lubrication nor cooling.

5 speed with 3.9 ratios are very nice for MIata turbo, only matched by 6 speed with expensive 3.6. So I view swap to 6 speed as 6 speed trans + 3.6 R&P, which ends up being a $1200+ upgrade. I know all why yes, but would love to hear if some have actually used their cars on the street with 5 speed without issues, with 300+whp?


thanks
alpinaturbo is offline   Reply With Quote
Old 10-20-2015, 09:47 PM   #2
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,362
Total Cats: 1,323
Default

No
Savington is online now   Reply With Quote
Old 10-20-2015, 09:57 PM   #3
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,184
Total Cats: 2,582
Default

Mechanical empathy will keep it alive for a little while but eventually it will fail
18psi is offline   Reply With Quote
Old 10-20-2015, 10:09 PM   #4
Elite Member
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,796
Total Cats: 248
Default

Quote:
Originally Posted by 18psi View Post
Mechanical empathy will keep it alive for a little while but eventually it will fail
This is my experience. If you're super easy on it as you say, it will probably work for a while. If you give it hell, you'll kill it. I lost 3rd in my 5 speed the first time I hit 3rd gear hard with 28 PSI on a GT3271.
patsmx5 is offline   Reply With Quote
Old 10-20-2015, 10:12 PM   #5
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,184
Total Cats: 2,582
Default

Mine lasted about a year at exactly 300 wheel and serious mechanical Empathy Street only

Last edited by 18psi; 10-20-2015 at 10:51 PM.
18psi is offline   Reply With Quote
Old 10-20-2015, 10:36 PM   #6
Junior Member
 
Join Date: May 2008
Location: Grants Pass, OR.
Posts: 449
Total Cats: 14
Default

3:90 work great with 6spds, I've had both and prefer 3:90's.
jmann is offline   Reply With Quote
Old 10-21-2015, 02:09 AM   #7
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2005
Location: Los Gatos, California
Posts: 67
Total Cats: -4
Default

Andrew,
Thanks...

I like to prod every technical dilemma, until I exhaust the options.
Reason for considering keeping the 5 speed is that I am over budget- way over - without 6 speed, on this "pushed by pushy MX-5 friends into build". Andrew knows the story, but it started by friend negotiating Codrus sale of our "community AEM ECU" to me...than worse yet buying a VVT Miata to use for core- its actually a nice Miata may I say. Sad to break it.

I enjoy soo soo much MX-5 community and love the modified cars you all produce, that its an incredibly satisfying experience. So the cost of the build is almost like paying dues, to enjoy the "culture". It's my 6th Turbo Roadster.

18PSI, Pat'sMX, thank you.
I can totally understand your experience based on other's friends experience.

Jmann, - you know, I just remember-ed that indeed it's been said that for track the 6 speed with 3.9 and turbo, is actually very good.
I've driven friends (MikeS) 1.9 w/3071 6 speed and 3.9, and never really thought anything other than it worked well together of it. 3.9 was not at all some kind of handicap, too close ratios.Now that I recall the experience.


OK. I guess I have to kiss goodbye more $$.
alpinaturbo is offline   Reply With Quote
Old 10-21-2015, 02:25 AM   #8
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,992
Total Cats: 1,459
Default

I didn't like 5 speed and 3.9. Felt slow. My car didn't like it either. 3rd gear went out at ~200ft/lbs.

What the hell is mechanical empathy? Pussies
aidandj is offline   Reply With Quote
Old 10-21-2015, 07:03 PM   #9
Senior Member
 
Join Date: Jun 2015
Location: TAMPA, FL
Posts: 644
Total Cats: 27
Default

Quote:
Originally Posted by 18psi View Post
Mechanical empathy will keep it alive for a little while but eventually it will fail
This has been my experience. You can keep it alive for quite a while by being gentle and careful, but it will eventually just die at those power levels. You really have to baby it. Definitely not suitable for track use or drag racing.
AlwaysBroken is offline   Reply With Quote
Old 10-21-2015, 11:55 PM   #10
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2005
Location: Los Gatos, California
Posts: 67
Total Cats: -4
Default

I've given in.
Now its decision time, which 6 speed to fetch.
Have choices form $450 to $900.
alpinaturbo is offline   Reply With Quote
Old 10-22-2015, 12:11 AM   #11
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,091
Total Cats: 90
Default

As long as you only floor it in 4th it'll last forever.
Leafy is offline   Reply With Quote
Old 10-22-2015, 12:57 AM   #12
Elite Member
 
codrus's Avatar
 
Join Date: Mar 2007
Location: Santa Clara, CA
Posts: 3,877
Total Cats: 344
Default

Quote:
Originally Posted by Savington View Post
No
Studying to be like Tony?

--Ian
codrus is offline   Reply With Quote
Old 10-22-2015, 12:59 AM   #13
Elite Member
 
codrus's Avatar
 
Join Date: Mar 2007
Location: Santa Clara, CA
Posts: 3,877
Total Cats: 344
Default

Quote:
Originally Posted by alpinaturbo View Post
I've given in.
Now its decision time, which 6 speed to fetch.
Have choices form $450 to $900.
You want one out of an MSM, and a 3.636:1 to go with it.

--Ian
codrus is offline   Reply With Quote
Old 10-22-2015, 02:02 AM   #14
Junior Member
iTrader: (1)
 
Join Date: Feb 2009
Location: Kamloops B.C.
Posts: 206
Total Cats: 24
Default

I'm running a MSM 6spd and 3.63 gear on the street with a GT 3071 . I went this route after watching a friend gernade two 5 speeds at 250ish hp and no mechanical empathy. Running 12-14 psi you're going to find the first three gears go by awful fast.
fredb is offline   Reply With Quote
Old 10-22-2015, 03:43 PM   #15
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2005
Location: Los Gatos, California
Posts: 67
Total Cats: -4
Default

Ian,

Tony is 1 of 1: his own customers find him "tight lipped" but I actually have spoken to him at work(his company) and off work a few times and he was quiet outspoken. And informative.

I am not going to indulge into 3.6..we'll leave this setup compromised to track-ability.

You are worse than drug-pushers, ruining a perfectly responsible family man into an emotional wreck filled with missed parts-buying/upgrades opportunities regrets.
alpinaturbo is offline   Reply With Quote
Old 10-22-2015, 11:27 PM   #16
Senior Member
 
Join Date: Dec 2010
Location: Auckland, NZ
Posts: 783
Total Cats: 23
Default

6 speed 1600 with 250 whp and 3.9 works great. Your power will be perfect for it.

A bit revvy on the road but track works well.
mx5-kiwi is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Transmission Heat Shield Thread patsmx5 General Miata Chat 46 06-06-2016 11:27 AM
Turbo stuff for sale at [email protected] this weekend gesso Miata parts for sale/trade 18 10-23-2015 10:26 PM
1.8 Crankshaft skou WTB 4 10-11-2015 04:42 PM
miata veteran, turbo n00b! 220swift Meet and Greet 2 10-07-2015 08:39 AM
Miata new person and a what's it worth! Model192 Meet and Greet 16 09-29-2015 09:50 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 07:03 PM.