F4R lightened crank

[BRT Motorsport]

anyone done any work on there F4R Crank

 

[marinemackay2003]

The 197 cranks are a little lighter iirc about 1.5kg rings a bell

 

[BRT Motorsport]

not much more to come off a 197 crank then ?

 

[Ph1 Tom]

Wouldn't have thought so. I'm sure there's a picture of them side by side somewhere.

 

[NorthloopCup]

You need to match the entire rotating assembly mate, not just the crank. Pistons and rods play a big part in how the engine balances out.

 

[EVOgone]

Are any mods needed to fit the crank, or is it a direct straight swap?

 

[BRT Motorsport]

have engine with steel rods,high comp pistons,cams, have a few months break, just looking to get bit more out of the engine

 

[BRT Motorsport]

are bolt patterns not different on the 197 crank

 

[NorthloopCup]

Are any mods needed to fit the crank, or is it a direct straight swap?

Direct swap mate

 

[NorthloopCup]

have engine with steel rods,high comp pistons,cams, have a few months break, just looking to get bit more out of the engine

Your better off going to a steel crank. What part broke?

are bolt patterns not different on the 197 crank

No they're the same.

 

[MiniCooper1380]

The 197 cranks are a little lighter iirc about 1.5kg rings a bell

Are you sure? I have these weights for F4R cranks:
172 Ph1 xx.xkg (but I think it's similar to 182 Ph3)
172 Ph2 12.8kg
182 Ph3 13.8kg
197 Ph1 14.5kg

 

[BRT Motorsport]

Hi Northloopcup
i was meaning few months break before competing again
no nothings broke just trying to get bit more power

 

[NorthloopCup]

Are you sure? I have these weights for F4R cranks:
172 Ph1 xx.xkg (but I think it's similar to 182 Ph3)
172 Ph2 12.8kg
182 Ph3 13.8kg
197 Ph1 14.5kg

Interesting. I weighed a 197 crank and a ph1 crank. The ph1 was heavier than the 197. I have a ph2 172 crank I can weigh for comparison to your figures.

Where did you get them from out of interest?

 

[NorthloopCup]

Hi Northloopcup
i was meaning few months break before competing again
no nothings broke just trying to get bit more power

You'll only get a few hp increase - if that tbh. You'll just gain a bit of reliability.

 

[BRT Motorsport]

ok cheers

 

[MiniCooper1380]

Where did you get them from out of interest?

I got them from Clio RS French forum.
F4R736 - Ph2

F4R738 - Ph3

 

[MiniCooper1380]

I think the 197 F4R830 crankshaft is the best for its 8 counterweight!:up:

 

[NorthloopCup]

I think the 197 F4R830 crankshaft is the best for its 8 counterweight!:up:

It's also the only one that was developed for a 7600rpm! I'll be using that in my build anyway.

 

[MiniCooper1380]

It's also the only one that was developed for a 7600rpm! I'll be using that in my build anyway.

Which weights did you mesure for Ph1 and 197 cranks?

 

[NorthloopCup]

Which weights did you mesure for Ph1 and 197 cranks?

I got the same as you have for the 197 crank and the ph1 172 weighed in at either 16kg or 15.8kg. Can't quite remember now.

 

[MiniCooper1380]

This is the minimum weight from fiche FIA for Clio 172 Ragnotti/Light/Cup:

 

[EVOgone]

So it heavier? Never heard of a crank break when using 8k, why use the 197 one then ?

 

[NorthloopCup]

So it heavier? Never heard of a crank break when using 8k, why use the 197 one then ?

Yep, but lighter than the ph1 172 crank. There's a relationship between rod weight, piston weight and crank weight but my mate who knows substantially more about these things can't explain/describe it to me. A lighter crank isn't necessarily the best way forward in some cases.

 

[EVOgone]

But the big point it was lighter which it isn't it heavier so why would you use a 197 one? 172 cranks don't break, or never heard of one doing so why bother.

 

[NorthloopCup]

But the big point it was lighter which it isn't it heavier so why would you use a 197 one? 172 cranks don't break, or never heard of one doing so why bother.

Why did Renault change the weight of the crank? Simple answer - I don't know mate and I'm not especially sure I care tbh. We've all learnt that the 197 crank isn't the lightest one so at least we all know. Nope f4r cranks don't break, but they can and do flex.

 

[BRT Motorsport]

anyone got standard torque figures between the different models, might give us a better answer

 

[gambit]

Big thread dig here: but over the last few years do we know anymore about the 197 crank weight combination with 197 rods and pistons in a 182 long block for higher rpm reliability etc?

 

[Coops Mk1]

depends how far you want to go but my build is totally stock 172 bottom end, phase 1 so maybe the heaviest crank but no one knows, and that's revved to 7800 limiter and mostly used for track. done 20 trackdays so far an nothings let go.....yet