Boosted folks with taller final drives... happy? - Page 2 - 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 10-31-2015, 04:36 PM   #21
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,199
Total Cats: 2,584
Default

1st/2nd gear sensor?
You mean just control boost by gear or boost by speed with the abs/speed sensors?
We've had that for years.

It's not the wheel spin most of us loathe, it's the constant shifting.
18psi is offline   Reply With Quote
Old 11-01-2015, 01:16 AM   #22
Senior Member
iTrader: (4)
 
2manyhobyz's Avatar
 
Join Date: Feb 2011
Location: Joliet, IL
Posts: 622
Total Cats: 16
Default

Quote:
Originally Posted by slmhofy View Post
I've got the Getrag 3.28 swap in my car. And coming from the MSM 4.10 w/6 speed which I pretty much hated once I started making power; I absolutely LOVE it.

Running 20psi ~ 275whp, there's still enough power to smoke the RS3s in 1st if they're not warmed up, second feels a little long, but everything else is great.
Where can I find out more about this rear end. I googled Getrag 3.28 and got stuff about mopar stuff. Sounds interesting.
2manyhobyz is offline   Reply With Quote
Old 11-01-2015, 01:22 AM   #23
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,199
Total Cats: 2,584
Default

search his threads. he's got a thread about it
18psi is offline   Reply With Quote
Old 11-01-2015, 01:23 AM   #24
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,199
Total Cats: 2,584
Default

18psi is offline   Reply With Quote
Old 11-01-2015, 01:11 AM   #25
Junior Member
iTrader: (5)
 
Join Date: Oct 2011
Location: San Diego, CA
Posts: 402
Total Cats: 21
Default

Quote:
Originally Posted by 2manyhobyz View Post
Where can I find out more about this rear end. I googled Getrag 3.28 and got stuff about mopar stuff. Sounds interesting.
It's awesome, beautiful and amazing. But not exactly what I'd call plug and play. Sorry. Drunk comment is still drunk
slmhofy is offline   Reply With Quote
Old 11-01-2015, 11:03 PM   #26
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,370
Total Cats: 1,332
Default

I've run a 6-speed with 4.10s, 3.909s, and 3.636s.

4.10s are ideal for track cars under 240whp or so. 3.909s work between 270 and 350whp, and north of 350whp, you want 3.636s for better traction in 3rd and 4th. 3.63s are too tall for ~270whp cars - 5th gear feels doggy on track with so much gear.

On the street, 3.636s are great, 3500rpm at 78mph, and you're never beating on the car in 5th on the street (or at least you shouldn't be), and the other gears are short enough that you don't feel like you NEED to downshift to go someplace.

I wouldn't mind a little more rev drop on the freeway with the 6sp/3.63s. A T5 box with G-Force's .75 overdrive will solve that, though.
Savington is offline   Reply With Quote
Old 11-02-2015, 12:03 AM   #27
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,999
Total Cats: 1,466
Default

Quote:
Originally Posted by AlwaysBroken View Post
I think the main problem everyone is trying to solve here is that high power turbo miatas are incredibly slow off boost and incredibly fast on boost and the transition happens about the middle of the rpm band.

This means that pretty much every first gear that is short enough to not bog off the line will bounce off the rev limiter once boost hits and any first gear long enough to not spin will either bog or eat clutches trying to get off the line fast. If the miata had a flat torque curve from 1500 rpm to redline, everyone would just run 50 mph first gears and call it a day.

The best solution (short of going SC or v8) is probably to just run a shortish first gear and limit power until 2nd/3rd to prevent spin. How hard would it be to rig up a 1st/2nd gear sensor for the miata? Once you have that, lowering the boost would be easy.

edit- I suppose you could just derive gear from the speedo cable- ie, below 30mph turn off boost control or substitute a pulse width of your choosing (selectable with a dial on the dash?)

edit2- wait a second I just remembered the miata uses a cable rather than electronic speedo cable... so where is my ECU getting the car's speed from? Anyone remember where to get a speed signal on the miata for something like an arduino?
Speed sensor is very easy. Use the search function. Run a single wire to the ECU for NA6, otherwise its already at the ECU. and profit.
aidandj is offline   Reply With Quote
Old 11-02-2015, 12:38 PM   #28
Junior Member
Thread Starter
 
Join Date: Sep 2015
Location: Memphis, TN
Posts: 165
Total Cats: 19
Default

Quote:
Originally Posted by AlwaysBroken View Post
I think the main problem everyone is trying to solve here is that high power turbo miatas are incredibly slow off boost and incredibly fast on boost and the transition happens about the middle of the rpm band.
Actually, that's not the problem I'm trying to solve at all....

Quote:
Originally Posted by AlwaysBroken View Post
This means that pretty much every first gear that is short enough to not bog off the line will bounce off the rev limiter once boost hits and any first gear long enough to not spin will either bog or eat clutches trying to get off the line fast.
Foremost, first gear is always going to spin. Nothing we're talking is meant to "solve" 1st gear traction loss. More to the reality, 1st gear is so incredibly short that it's useless for damn-near anything unless towing or a 15% incline are involved. Maybe both.

Also, why are the ONLY two options bog or bounce redline? Are we talking on the strip or the street? Because I'm reasonably confident that a turbocharged application can be reigned in with throttle management. Unless the pedal is pinned to the carpet, I can be reasonably sure of keeping it off the revlimiter.

Quote:
Originally Posted by AlwaysBroken View Post
If the miata had a flat torque curve from 1500 rpm to redline, everyone would just run 50 mph first gears and call it a day.
This seems like a non-sequitur. I'm never going to "launch" at 1500RPM under race circumstances, and if I"m just tooling around on the streets I'm never going to be at such low RPM's unless I've completely stopped. Nobody is asking for a 50mph first gear, unless we're talking about a 250mph Miata here...

Quote:
Originally Posted by AlwaysBroken View Post
The best solution (short of going SC or v8) is probably to just run a shortish first gear and limit power until 2nd/3rd to prevent spin. How hard would it be to rig up a 1st/2nd gear sensor for the miata? Once you have that, lowering the boost would be easy.
Throttle management solves all of this.

The best solution for me is to stretch ALL the gears rather than invoke even more pain with electronic management that further removes me from the decision making. The only place I *might* consider electronic management is in 6th gear, and ONLY because the NC's 6th gear with ~350tq applied tends to rip off all the teeth. Since I have zero interest in EVER going for land-speed records, I have considered using some gear-aware EBC just to ensure I keep it low and slow in 6th.

Based on the other feedback in this thread, it looks like my head is in the right direction. The lowest I've found (native, factory option) for the NC is the 3.72 set, but I can also see other options either with replacement pumpkins or special kits to retrofit other R&P sets.

For what I'm trying to accomplish, the 3.7 is probably fine.
albuquerquefx is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Turbo ND? Cool car Corky Bell Prefabbed Turbo Kits 23 02-11-2016 02:42 PM
Ok flame me but idle question 90 Turbo MEGAsquirt 11 11-16-2015 08:13 PM
My Flyin' Miata v-maxx review from track records to cruising with my gal blkmkiii Suspension, Brakes, Drivetrain 15 11-05-2015 11:58 AM
AFRs read rich and car bogs on acceleration Chiburbian MEGAsquirt 6 10-27-2015 03:27 PM
Anyone in the Sacramento, CA area have storage space? miata, tools, one set of tires thumpetto007 General Miata Chat 2 10-26-2015 01:58 AM


Tags
nc boost ring pinion n00b

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 04:17 AM.