Hi all, looking for some advice.

Running a cossie engine (352bhp and 380ft lb of torque) in a rear wheel drive fiesta. Its got an atlas axle with a 4.6 diff in it. I broke something on a track day yesterday, think its a rear half shaft. Got to fix that and wanted to change the CWP while i am at it; wondered what people are using as the 4.6 is way too short for track days I feel.

I am using a standard T5 box.

Also, would i need a remap once new CWP is in?

Thanks

Matt

 

Shafts are the weakest link on an atlas, I change too uprated 21 spline ones on my car.
the 4.6 ratio would be a p100 ratio and quite sought after, I found the 3.75 standard fitment on a mk3 1.6 Capri the best compromise. Still have a top speed of close too 160mph but good acceleration too. My car is 500hp with a standard t5 and 3.75 atlas.

 

Great that is really helpful, thanks. Do you think the acceleration will still be ok on a 3.75 with only 350bhp? What sort of speeds do you get in 2nd and 3rd? Doubt I will ever get up to 160mph haha

 

Depending if your running 15 inch wheels 4.1 would be good ,still have the acceleration and will still be good for over 140mph

 

Thanks for this, running 16" wheels so assume this would be even more than 150 top end? Was only getting around 127 with the 4.6

Thanks!

 

depends what your reving to but even if it’s 7000 rpm on 16s it will be between 140-150 and 4th Gear will be 120 Something

 

I just remembered I had a mk2 van ybt on 13s and 4:1 that pulled over 140 mph,on t34 and greens

 

perfect, thanks for your help. Revving 6800 so I reckon 4.1 will be bob on!