Ford Mustang Forums banner

1 - 17 of 17 Posts

·
Registered
Joined
·
471 Posts
Discussion Starter #1
So, if you dyno at 362 RWHP through an AoD with a lockup converter, what would the RWHP be with a 5-speed? Is it better to use a percentage change or go with a fixed amount for the AoD like 40HP?
 

·
Registered
Joined
·
471 Posts
Discussion Starter #3
..but...but...but I had to use 347 cubic inches to get my 362HP and you only needed 302 cubic inches to generate 368 HP. From a horsepower stand point, you are getting more done with less. When I was running the 302 short block with the same setup and a Cobra intake I only managed 302 rwhp. Once again falling way short of the horsepower number you generated. Now, to be honest, that combo ran [email protected] in great air.
 

·
Registered
Joined
·
1,684 Posts
but... but... but... LOL!
maybe you need to come drive mine for me:).
how great was the air, and what was the race weight? Just asking for comparison given the 113mph, as, I know my car has more in it... errr... the driver really needs work, but the 11.75 sounds great for 113mph, giving me hope... or shame... I go back and forth on that.
 

·
Registered
Joined
·
471 Posts
Discussion Starter #5
Race weight was right around 3050. No driver mod could save me, hence the AoD transmission. Back then I was putting down 1.57 60fts on 235-15 MT Drag radials. I was running in a 12.0 index class that was run on a pro tree. In the heat with DAs around 2500-3000 I was running 12.1x deep staged. The 11.75 was run shallow staged and the DA around 250ft. Tom Moss ported the Cobra intake and Buddy Rawls spec'ed the cam in that combo.
 

·
Registered
Joined
·
471 Posts
Discussion Starter #7
What would the RWHP and RWT differences be if the only change was from an AoD with lockup to a T5 manual transmission? The only data points for reference I have are for a car going from a regular 3 speeds automatic (904) to an overdrive automatic (A500). Both transmissions used the same torque converter as I had the A500 converted to non-lockup. The result was the car with the overdrive transmission slowed down 4 tenths and 4 MPH.

Does anyone have any before and after dyno numbers when they swapped from an automatic to a manual?
 

·
Premium Member
Joined
·
2,572 Posts
What would the RWHP and RWT differences be if the only change was from an AoD with lockup to a T5 manual transmission? The only data points for reference I have are for a car going from a regular 3 speeds automatic (904) to an overdrive automatic (A500). Both transmissions used the same torque converter as I had the A500 converted to non-lockup. The result was the car with the overdrive transmission slowed down 4 tenths and 4 MPH.

Does anyone have any before and after dyno numbers when they swapped from an automatic to a manual?
Don't have dyno numbers, but it is generally assumed that the difference is about 5% or so. Another benefit is that the T-5 is substantially lighter than an AOD. There is also a big difference in one auto to another. As an example a built PG weighs 70 lbs less than a AOD and consumes 70 less HP less to operate at max load.
 

·
Registered
Joined
·
471 Posts
Discussion Starter #9
So...if I put a PG in my car in place of the AoD I would run 10.XX at 127.55 MPH? Maybe 125MPH with the additional converter slippage ;-)
 

·
Premium Member
Joined
·
2,572 Posts
Depends on the gearing and power. A glide can slow you down in the wrong application. Generally the 2 speeds are 1.84:1 in low and 1:1 in high. If you don't make enough power then the tall low gear can kill your 1/4 times.
 

·
Registered
Joined
·
4,138 Posts
I went from 720hp to 580hp when I swapped in the 4R70 from a manual with no other changes. The converter was locked so no slipping.

ks
 

·
Registered
Joined
·
471 Posts
Discussion Starter #12
Wow!!! Losing 140 HP with a transmission change is crazy. Tell me the car didn't slow down like it lost 140 HP.
 

·
Registered
Joined
·
4,138 Posts
Wow!!! Losing 140 HP with a transmission change is crazy. Tell me the car didn't slow down like it lost 140 HP.
It was a turd after the swap. We eventually got it back up to 700hp with more boost and a tune change but it was a night and day difference. Now the car is making 900hp with more boost and a few other changes but that trans swap ate up a lot of HP.

ks
 

·
Registered
Joined
·
5,227 Posts
You'd be around 400-420 rwhp through a manual. But it's really a pointless metric - way too many variables (dyno type, tires, rear gear, correction factor, weather (yes that makes a difference even with correction), etc.) Use the dyno as a relative tuning tool. I dyno'd ~560 rwhp and went 9.88 at 137.xx at 3,443 lbs. Found out that the dyno loads the car harder than the strip, causing my converter to slip 30% on the dyno, and about 11-12% on the track.
 

·
Registered
Joined
·
32 Posts
I had a friend switch from 4R70W to a C4 and times improved 2/10 ths. Factor in the C4 was 60 lbs lighter and converter was now a 8" instead of 9.5". I always figured the AOD was about 5% to 8% more parasitic loss compared to stick car.
 

·
Registered
Joined
·
38 Posts
It was a turd after the swap. We eventually got it back up to 700hp with more boost and a tune change but it was a night and day difference. Now the car is making 900hp with more boost and a few other changes but that trans swap ate up a lot of HP.

ks

On a smaller scale, I experienced the exact same. My street car would run mid 7s in the 1/8 @ 92 mph with a C4. Swapped to a 4r70w and it slowed down to 7.9s @ 85 mph. I got it back to run 7.6s with the same motor but the mph is way off at 87.

The internal mass of a 4r70w is about 50 pounds more than a C4, and most of that is parasitic rotational mass. That is why they cost so much in e.t. and mph.
 
1 - 17 of 17 Posts
Top