Turbo 1.8 NA, 240whp, 7.5 Ford rear, what gears? - 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 08-01-2013, 01:47 PM   #1
Newb
Thread Starter
 
Join Date: Aug 2013
Posts: 6
Total Cats: 1
Default Turbo 1.8 NA, 240whp, 7.5 Ford rear, what gears?

Hey all! I picked up a '97 NA Miata, and I'm trying to sort out what gear set I want to swap to. The car is on 12 psi, currently makes 240whp. It has a Ford 7.5 rear end, currently with 4.10s in it. With the torque this car makes, I don't see any reason to run around at 4,000 rpm at freeway speeds, as well as first through third gears being practically unusable. So, I'm going to step down the gear ratio, but I'm unsure exactly what I want to run. I'm in between a 3.73 and probably a 3.55. I've researched and seen people saying that under 18 psi you want a 3.73, but I'm not sure that a 3.73 will drop my freeway rpm all that much, and would give me a little more headroom for more power later. Conversely, I don't want to go too long of a gear and put too much stress on the motor trying haul around too long of a gear. I just don't want to do the one and then wish I went the other way. What are your thoughts? I'm all ears, thank you!
20psirabbit is offline   Reply With Quote
Old 08-01-2013, 01:50 PM   #2
Elite Member
iTrader: (5)
 
Erat's Avatar
 
Join Date: Oct 2011
Location: Detroit
Posts: 4,191
Total Cats: 260
Default

240whp
180torque

What's wrong with the 4.10? Can't use the first 3 gears? Why not? Put a better tire on it, i hooked with a 195 tire, a little less HP and 4.10 gears.
Erat is offline   Reply With Quote
Old 08-01-2013, 01:52 PM   #3
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,171
Total Cats: 2,574
Default

First - is this is a street car or race car?
Second - is the engine built? Do you plan to run more in the future?
Third - is it on the stock 5 speed or 6 speed?
18psi is offline   Reply With Quote
Old 08-01-2013, 01:52 PM   #4
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,831
Total Cats: 1,786
Default

Quote:
Originally Posted by 20psirabbit View Post
With the torque this car makes...I'm going to step down the gear ratio [to] 3.55...
Attached Thumbnails
Turbo 1.8 NA, 240whp, 7.5 Ford rear, what gears?-huge_bow_rofl_crowd.gif  
Braineack is online now   Reply With Quote
Old 08-01-2013, 01:58 PM   #5
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,171
Total Cats: 2,574
Default

Not enough smileys need moar
18psi is offline   Reply With Quote
Old 08-01-2013, 02:15 PM   #6
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,831
Total Cats: 1,786
Default

Quote:
Originally Posted by 18psi View Post
Not enough smileys need moar
Attached Thumbnails
Turbo 1.8 NA, 240whp, 7.5 Ford rear, what gears?-rolleyesbarf2.gif  
Braineack is online now   Reply With Quote
Old 08-01-2013, 02:19 PM   #7
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,653
Total Cats: 1,559
Default

You aren't making enough horsepower for the 355 gears. use the 373.
sixshooter is online now   Reply With Quote
Old 08-01-2013, 02:36 PM   #8
Elite Member
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,460
Total Cats: 782
Default

Quote:
Originally Posted by 20psirabbit View Post
Hey all! I picked up a '97 NA Miata, and I'm trying to sort out what gear set I want to swap to. The car is on 12 psi, currently makes 240whp. It has a Ford 7.5 rear end, currently with 4.10s in it. With the torque this car makes, I don't see any reason to run around at 4,000 rpm at freeway speeds, as well as first through third gears being practically unusable.
Are you running Walmart MayPop tires or something?

Quote:
So, I'm going to step down the gear ratio, but I'm unsure exactly what I want to run. I'm in between a 3.73 and probably a 3.55. I've researched and seen people saying that under 18 psi you want a 3.73
I wasn't aware that psi was a direct correlation to rear end gearing.... unless you're talking about tire pressure?

Quote:
, but I'm not sure that a 3.73 will drop my freeway rpm all that much, and would give me a little more headroom for more power later. Conversely, I don't want to go too long of a gear and put too much stress on the motor trying haul around too long of a gear. I just don't want to do the one and then wish I went the other way. What are your thoughts? I'm all ears, thank you!
With how little power you're making, i'd do like... a 3.9. Maybe a 3.73 if you're feeling especially froggy.


Sincerely,

Someone who makes more power than you yet manages to dead hook 1st, 2nd, and 3rd with a 6spd and a 4.10.
concealer404 is offline   Reply With Quote
Old 08-01-2013, 04:18 PM   #9
Newb
Thread Starter
 
Join Date: Aug 2013
Posts: 6
Total Cats: 1
Default

This forum is spicy, I like that
Sorry about that, I had a feeling missed a couple of pieces of information.
-The car is a street car that may see some track days, but primarily a street toy.
-It's a 5 speed trans.
-While I'm not under the impression that the car is terribly fast, what I meant with the torque comment is that it's got enough bottom end that a little less gear isn't going to make it call on it's face. But I hate driving around at 4,000 rpm on the freeway at ~75mph. Also, I live in Las Vegas, and the streets are fairly greasy (my c6 z06 goes sideways at WOT till 150mph, even my bolt-on 135i spins through the top of third)
-At this point, the car is on a stock block. Whenever it decides to check out, I'll build it bigger and better.
20psirabbit is offline   Reply With Quote
Old 08-01-2013, 04:23 PM   #10
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,355
Total Cats: 1,322
Default

I'd do a 3.55 and a Miata 6-speed to match. Gears should be similar to what you have now with an extra cog for cruising. The 6-speed also has shorter drops between gears so the car should be a little faster.
Savington is offline   Reply With Quote
Old 08-01-2013, 04:25 PM   #11
Elite Member
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,460
Total Cats: 782
Default

Funny you mention that...

I was just in LA about 3.5 weeks ago. My car had no problems hooking. I'm betting you have other problems.


Anyways, the Miata motor is perfectly happy turning those RPMs. If for some reason it bugs you, i'd suggest the 3.73 at the most. Going further will start to suck when it comes to the bottom gears if you're only making 180wtq.

I did 7500 miles of this in 3 weeks and it wasn't a big deal. Do i want a 3.9 or a 3.63? Sure. Is the 4.10 ruining the car? Nah.

Attached Thumbnails
Turbo 1.8 NA, 240whp, 7.5 Ford rear, what gears?-20130629_173836.jpg  
concealer404 is offline   Reply With Quote
Old 08-02-2013, 09:52 AM   #12
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,091
Total Cats: 90
Default

Lets see upgraded the diff that can easily handle north of 300ftlbs, left the transmission that asplodes at 250ftlbs.

Attached Thumbnails
Turbo 1.8 NA, 240whp, 7.5 Ford rear, what gears?-guinness-brilliant-1-tagged-2-1.jpg  
Leafy is offline   Reply With Quote
Old 08-02-2013, 10:41 AM   #13
Newb
Thread Starter
 
Join Date: Aug 2013
Posts: 6
Total Cats: 1
Default

Quote:
Originally Posted by Leafy View Post
Lets see upgraded the diff that can easily handle north of 300ftlbs, left the transmission that asplodes at 250ftlbs.

I didn't build the car smart ***, I just picked it up as is. Nice try.
20psirabbit is offline   Reply With Quote
Old 08-02-2013, 10:56 AM   #14
Elite Member
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,460
Total Cats: 782
Default

Doesn't matter either way if he's only making 180ftlbs. I can only imagine how slow that thing is.
concealer404 is offline   Reply With Quote
Old 08-02-2013, 12:41 PM   #15
Newb
Thread Starter
 
Join Date: Aug 2013
Posts: 6
Total Cats: 1
Default

Quote:
Originally Posted by concealer404 View Post
Doesn't matter either way if he's only making 180ftlbs. I can only imagine how slow that thing is.
It might be slower than your car, which is slower than my other cars. Your point?
20psirabbit is offline   Reply With Quote
Old 08-02-2013, 12:44 PM   #16
Elite Member
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,460
Total Cats: 782
Default

Quote:
Originally Posted by 20psirabbit View Post
It might be slower than your car, which is slower than my other cars. Your point?

The point is that it's going to be almost unenjoyable going much lower than a 4.10 numerically.


What sort of turbo is on this thing that it's making 240whp/180wtq? That's really bizarre and uncommon, and stupid.


I don't know why we're bringing my car into this. It's not relevant, nor do you know what it is. Get your e-thug on though, hotshot. *** in my ***.
concealer404 is offline   Reply With Quote
Old 08-02-2013, 12:46 PM   #17
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,091
Total Cats: 90
Default

Quote:
Originally Posted by concealer404 View Post
The point is that it's going to be almost unenjoyable going much lower than a 4.10 numerically.


What sort of turbo is on this thing that it's making 240whp/180wtq? That's really bizarre and uncommon, and stupid. *** in my ***.
GT3571R on low boost
Leafy is offline   Reply With Quote
Old 08-02-2013, 12:48 PM   #18
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,171
Total Cats: 2,574
Default

his point is you're wasting your time asking the wrong questions.

what you should be researching is a transmission upgrade, then a motor upgrade, and only after all that you should be considering changing the fd
18psi is offline   Reply With Quote
Old 08-02-2013, 12:48 PM   #19
Elite Member
iTrader: (5)
 
Erat's Avatar
 
Join Date: Oct 2011
Location: Detroit
Posts: 4,191
Total Cats: 260
Default

I don't think he said how many torques it makes. I just assumed it was 180 because he claimed 240hp. And we all know the horsepowers count.
Erat is offline   Reply With Quote
Old 08-02-2013, 12:52 PM   #20
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,171
Total Cats: 2,574
Default

get a proper transmission in there, then build the engine, then turn it up ALL THE WAY and only then go to a low fd like 3.55 or whatever your lowest option is
18psi is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
91 1.6l turbo complete part out. Tony the Tiger Miata parts for sale/trade 63 12-29-2016 03:23 AM
Twitchy car (tail happy problem) bigben Race Prep 16 09-11-2015 04:41 PM
WTB 1.8 manifold and turbo (preferred ball bearing) AnotherDamnMiata WTB 13 09-11-2015 11:56 AM
Grinding into 5th and coasting shanesauce General Miata Chat 1 09-06-2015 09:47 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.