• Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech

Stock Auto Tranny MAx Horsepower

  • Thread starter Thread starter wide
  • Start date Start date Dec 31, 2004
W

wide

New Member
Dec 31, 2004
4
0
0
Dec 31, 2004
#1
  • Dec 31, 2004
  • #1
I just bought a 2000 GT Convertible last week.

What I would like to do is add a little more power to make up for the fact that I bought an Automatic. I was gonna start with an air intake and exhaust. I figure that should be good for the 25 horses I probably lost relative to the manual. My question is this though...

How much horsepower can I get my engine to produce with absolutely no problems from the stock automatic transmission. I have no desire (at the moment) to add more than 50 HP. Is this OK on the stock tranny?

Thanks
 

speed545

Member
Mar 21, 2003
458
1
18
Montreal, canada
Dec 31, 2004
#2
  • Dec 31, 2004
  • #2
wide said:
I just bought a 2000 GT Convertible last week.

What I would like to do is add a little more power to make up for the fact that I bought an Automatic. I was gonna start with an air intake and exhaust. I figure that should be good for the 25 horses I probably lost relative to the manual. My question is this though...

How much horsepower can I get my engine to produce with absolutely no problems from the stock automatic transmission. I have no desire (at the moment) to add more than 50 HP. Is this OK on the stock tranny?

Thanks
Click to expand...

Welcome to the board
First mod to do to compensate your desavantage to the 5sp is 4.10 gears.
Beleive me it s working
As far as HP goes, 4R70W can take WAYYYYYYYY much than 50RWHP. Those tranny can probably handle, when taking care of, 400RWHP.

Dont forget a good tranny cooler also!!!!

Have fun
 
W

wide

New Member
Dec 31, 2004
4
0
0
Dec 31, 2004
#3
  • Dec 31, 2004
  • #3
speed545 said:
Those tranny can probably handle, when taking care of, 400RWHP.

Dont forget a good tranny cooler also!!!!

Have fun
Click to expand...

400 RWHP,, holy shi$, I find that a little hard to believe, but I hope it's true.
 

speed545

Member
Mar 21, 2003
458
1
18
Montreal, canada
Dec 31, 2004
#4
  • Dec 31, 2004
  • #4
wide said:
400 RWHP,, holy shi$, I find that a little hard to believe, but I hope it's true.
Click to expand...

On MD forum, a guy manage to race a full season on a stock 4R70W with around 550RWHP before getting some problems. Another one is putting around 300 RWHP on also a stock 4R70W without anyproblems.
They are good tranny, just need to take care of it.
 

CManT1914

New Member
Feb 5, 2004
3,172
2
0
Killeen, Texas
Dec 31, 2004
#5
  • Dec 31, 2004
  • #5
You shouldn't have any problems with the tranny, but first you should get some gears (maybe 4.10's) for sure. That will make a HUGE difference in the performance. You might do those and decide to leave well enough alone.
 
B

bdcardinal

tree hugger
Jun 10, 2003
3,612
16
69
santa barbara, CA
Dec 31, 2004
#6
  • Dec 31, 2004
  • #6
you can leave the transmission stock internally, however adding an auxillary cooler will help a lot. also keep the fluid in there flushed and pink. change it evey year with a good synthetic Mercon V ATF. also make sure when you change the fluid to change the filter and to never do the flush type thing that dealers and quick lube places offer.
 

Gearbanger 101

Straight Outta Locash
20+ Year Stangneter
Aug 10, 2002
9,457
1,377
234
Ontario, Canada
Dec 31, 2004
#7
  • Dec 31, 2004
  • #7
Mehhh, some say that the 4R70W sucks in comparison to a 5-speed (usually 5-speed owners )....and in stock trim, I might tend to agree. But couple it with shift reprogramming, a stall converter and 4:10 gears and you'll be showing 5-speed guys your taillights and running more consistent times as speeds than them all day long.
 
W

wide

New Member
Dec 31, 2004
4
0
0
Jan 2, 2005
#8
  • Jan 2, 2005
  • #8
Gearbanger 101 said:
Mehhh, some say that the 4R70W sucks in comparison to a 5-speed (usually 5-speed owners )....and in stock trim, I might tend to agree. But couple it with shift reprogramming, a stall converter and 4:10 gears and you'll be showing 5-speed guys your taillights and running more consistent times as speeds than them all day long.
Click to expand...

Sounds like a plan to me
 
W

wide

New Member
Dec 31, 2004
4
0
0
Jan 2, 2005
#9
  • Jan 2, 2005
  • #9
Anybody know what kind of 1/4 mile differences you get from switching gears only. on the auto
 

CManT1914

New Member
Feb 5, 2004
3,172
2
0
Killeen, Texas
Jan 2, 2005
#10
  • Jan 2, 2005
  • #10
As long as you don't have traction problems already, then maybe .5 seconds.
 
S

STNGLVR

New Member
Jan 2, 2005
1
0
0
NY
Jan 2, 2005
#11
  • Jan 2, 2005
  • #11
I HAVE A 99 GT AUTO W/80K MILES. I BOUGHT IT W/50K MILES AND I GUESS THE PREVIOUS OWNER BEAT ON THE CAR CAUSE THE WAY THE TRANNY SHIFTS SUCKS BIG TIME! ANY HELP TO IMPROVE?
 
B

bdcardinal

tree hugger
Jun 10, 2003
3,612
16
69
santa barbara, CA
Jan 2, 2005
#12
  • Jan 2, 2005
  • #12
STNGLVR said:
I HAVE A 99 GT AUTO W/80K MILES. I BOUGHT IT W/50K MILES AND I GUESS THE PREVIOUS OWNER BEAT ON THE CAR CAUSE THE WAY THE TRANNY SHIFTS SUCKS BIG TIME! ANY HELP TO IMPROVE?
Click to expand...

first off try hitting the caps lock, we dont need to yell around here.

check the condition of the fluid, how does it look? is it brown and stinky, or pink? if its brown try changing it, dont go get a flush, drop the pan, change the filter, drain the torque converter, and refill with fresh Mercon V. this should help out a decent amount. just be aware that if the fluid is like black and it smells like a BBQ then you are looking at getting a trans rebuild. ive seen 4R70Ws go bad within 15k miles of hard driving.
 
You must log in or register to reply here.

Similar threads

A
2001 Mustang GT, scorched metal smell and noise from trans/diff?
  • AndyE2255
  • Dec 1, 2025
  • SN95 4.6L Mustang Tech
Replies
4
Views
465
SN95 4.6L Mustang Tech Dec 28, 2025
gkomo
Progress Thread Progress Thread- From6to8's 95 GT/Saleen Supercharged 331 install
  • from6to8
  • Mar 22, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
24
Views
935
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- May 6, 2026
from6to8
0
V6 to V8 Swap info
  • 02_2v_Curtis
  • Jan 11, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
731
1996 - 2004 SN95 Mustang -General/Talk- Jan 11, 2026
02_2v_Curtis
0
J
Progress Thread Family member 1989 GT- Backstory and updates
  • JRC99
  • Apr 19, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
15
Views
1K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Oct 26, 2025
JRC99
J
T
  • Locked
1990 2.3L automatic - real bad engine sputtering
  • the_steve_randolph
  • Jun 13, 2024
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
10
Views
1K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jun 14, 2024
the_steve_randolph
T
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?