crank to rwhp ? dyno tpyes ?

[ghostrider7953]

#1 Using an example of 625 crank hp on an automatic. I know there is a 20% reduction ; so 625 crank theoretically becomes 500 rwhp. Does a 3:31 gear ratio reduce that rwhp or does it have any affect at all ?

#2 I've been told a Mustang dynojet reads lower than a dynojet; if so how much lower ?

Thanks
TD

 

[manolith]

taller gearing like the 3.31 usualy gives a few more ponies on the dyno than lower gearing like 3.73 or 4.10

mustang dynos are usually heart breakers meaning read low and sometimes really low. but again dyno numbers are not to show off on the forums is mostly only to tune the car and see if you gained anything from mods on that same dyno.

 

[ghostrider7953]

Thanks

 

[AntiHeightPunk]

ricer math

 

[UnleashedBeast]

ricer math

:lol:

 

[mhyjek]

I don't know the average what and auto does but for example say your auto mustang dynoed 355 stock. I would say the driveline takes away 65 hp so a 625 hp auto should dyno 560 hp.

 

[AntiHeightPunk]

what are all these guesses based on

 

[01bluesnake]

Newer autos are pretty good about loss, I would guess about 15%. As far as dyno, they are all pretty close and should be used as a tuning tool. SAE and standard settings for the dyno graph make a difference as well

 

[Blazer707@TBR]

taller gearing like the 3.31 usualy gives a few more ponies on the dyno than lower gearing like 3.73 or 4.10

mustang dynos are usually heart breakers meaning read low and sometimes really low. but again dyno numbers are not to show off on the forums is mostly only to tune the car and see if you gained anything from mods on that same dyno.

Wasn't this disproved multiple times. Gearing does not change your RWHP output.

-Thomas

 

[nosympathy]

Newer autos are pretty good about loss, I would guess about 15%. As far as dyno, they are all pretty close and should be used as a tuning tool. SAE and standard settings for the dyno graph make a difference as well

I've heard 14-15% loss on the autos and 11-12% on the manuals. Neither of the two loose as much power as they used too.

 

[manolith]

Wasn't this disproved multiple times. Gearing does not change your RWHP output.

-Thomas

no i dont think so.. if you have 4.10s your engine will have to do more work to turn the tire once when compared to a 3.31 gear for example.

 

[ghostrider7953]

Now for the rest of the story....
I had the Roush 625 hp upgrade installed on my 2011 automatic. Dyno'd on a Mustang dyno in 3rd gear , on a day with a heat index of 104 and dyno'd 439 at 5000 rpms. I wanted the Roush tune cleaned up. Better throttle response, no more discolored tail pipes and more safe power.
I spoke with different tuners, different forum members and did my research. I felt comfortable with JDM Engineering (Jim sr, JimIII & Nick Sezz) and had them do a tune for my ride. I still don't understand the black box voodoo of tuning; all I know is their tune gave me 500rwhp & 455 TQ on a mustang dyno. The throttle response is there, idles smoothly with/ without Ac on and definitely has more power. Jim told me that if I wanted more power then move from an 85 mm pulley to an 82 mm with a retune I should pick up another 25-30 rwhp. He also suggested going to a dyno jet which seems to be the norm for dynos; it will give me a better picture of my rwhp.

 

[ghostrider7953]

PS: I'm 60 yrs old ,very old school and really amazed how cars today are "tuned." My first ride, probably when most of you were in diapers, was a 71' Mach 1. The 71' s power couldn't hold a candle to my 11' Roush charged pony.
I can't imagine what it would be like to control the power that some of you guys have.
Have a good one.
Pappy