Roush 427RX Engine

[Stefano75]

anyone installed this racey 675HP@7500RPM engine in his 40 and if so what about the zf transaxle with longer gear ratios?

what if fuel is premium 100 octane gasoline not 110 as suggested by roush??

thanks in advance
Stefano

 

[Simon Rider]

Hi Stefano,
i'm sure more knowledgable folk will chime in, but i think this is a pretty hardcore race engine that might be a bit of a handfull on the road if that's your intention. Things like single plane manifolds suggest the power is in the top end at the expense of low end drivability, also flat tappits need more maintainance to keep the proper lash clearances.
As for the suggested octain - the US use a different rating than in Europe, so 110 ovwer there equates to more than 110 in Europe - even if available anywhere outside a racetrack. Using lower rated fules will bring about damaging 'detonation' caused by premature ignition of the fuel-air mixure under high compression.
I'd go for something softer if you're looking for a streetable motor.

Just my .02p

 

[Stefano75]

i have found in this forum :heart: an utility that calculates speed in each gear just setting each gear ratio, tyre size and rev limit of the engine....
the output is outstanding every single thougt i made for the configuration of the car i made..

that engine revving at 7500Rpm can push my 40 over 300Mph (480Kmh) :stunned: simply by switching medium to long final ratio or 265Mph (424Kmh) without any change to the standard setting suggested by superformance!!!
the only doubt left is the acceleration time....

i wander what i can do to a ferrari enzo or lamborghini murcielago if they want to push....
i think it is too much even for a racecar.... maybe is the case of switcing the final for a shorter one?

 

[Stefano75]

Hi Stefano,
i'm sure more knowledgable folk will chime in, but i think this is a pretty hardcore race engine that might be a bit of a handfull on the road if that's your intention. Things like single plane manifolds suggest the power is in the top end at the expense of low end drivability, also flat tappits need more maintainance to keep the proper lash clearances.
As for the suggested octain - the US use a different rating than in Europe, so 110 ovwer there equates to more than 110 in Europe - even if available anywhere outside a racetrack. Using lower rated fules will bring about damaging 'detonation' caused by premature ignition of the fuel-air mixure under high compression.
I'd go for something softer if you're looking for a streetable motor.

Just my .02p

thanks for your appreciate suggestion i'll be thankful to anyone who'll share his knoledge as you...

 

[EGLITOM]

i have found in this forum :heart: an utility that calculates speed in each gear just setting each gear ratio, tyre size and rev limit of the engine....
the output is outstanding every single thougt i made for the configuration of the car i made..

that engine revving at 7500Rpm can push my 40 over 300Mph (480Kmh) :stunned: simply by switching medium to long final ratio or 265Mph (424Kmh) without any change to the standard setting suggested by superformance!!!
the only doubt left is the acceleration time....

i wander what i can do to a ferrari enzo or lamborghini murcielago if they want to push....
i think it is too much even for a racecar.... maybe is the case of switcing the final for a shorter one?

Hi Stefano

Although your calculation is correct ( 5th gear 0,642 and final ratio 3,2) it is very theoretical.

• All assumptions on this forum end at top speed of 200 mph, max 220 mph
• this because of the aerodynamics of the GT40
• in standard config ( without splitter or ground effect bars,) the car is not known to create a downforce at high speeds, it is rather more known to create a lift. Although i haven´t seen any windchannel test.( some info is on Ford GT Replica - supercar - custom classic - Xtreme Classics)
• So i wouldn´t be trying anything higher than 200 mph
• drag is increasing dramatically at this speeds and i doubt that even with this power the car would go faster than 200 mph.
• it is a 40 year old construction, which in no way is up to the standards of the cars you refere to ( this cars are actually creating a heck of downforce at speeds)

The fascination of the GT40 is more related to the history, to one of the greatest designs ever; to the feeling the car gives back to you. In terms of perfomance it is definitely a very fast car and will outperform almost every car on the street with a very capable driver at the wheel, but 500 HP is plenty to give you a thrill and challenge all the time.
Don´t let yourself drive away by unrealistic expectations which afterwards won´t be fullfilled and leaves you very dissapointed.

Hope you accept my transparency and open communication

TOM

 

[Stefano75]

of course your appoint is more than correct it was my same thaugt it is impossible for a car run that speed even with higher power unless it is a 4 weel rocket :shocked2:
that's why i was thinking how lower the final ratio i can't figure anyway how much it could be correct.... :thinking2:

same thing about horsepower i agree too much power is useless and the stress given to the drivetrain may cause serious damage to the gearbox that is not tested for powers exceeding 500hp....
i made a mistake not considering this things, and there is also the problem about the fuel that engine needs that is unavailable here in italy

thank you for your advices i really appreciate that