Anyone bored out an F4R?

[Chris205]

As title really, has anyone done it and what sort of experiences/reliability have you had afterwards?

 

[Fred@BTM]

a few of us have, no real point really as you can't go more than 2.1 (ish)

so why then you ask?

our block was a bit tired on the bores so we went up a piston and started from fresh, but we increased the comp ratio by a fair old chunk, so it turned out nigh on a 2.0 still

 

[f0xy]

http://www.cliosport.net/forum/showthread.php?364943-Racing-Blue-ph1-ITB-2010-track-season-updates/

 

[Icarus]

You can go to 84mm without any real issue which gives you just over 2061 CC but that's about the limit.

 

[Chris205]

Not really from a performance perspective just wondering if the F4R block handled being opened up. Were 'said' cars reliable etc afterwards. My car is a daily so it needs to work fine lol

How would the car run bored out with standard cams and intake but once ran in custom mapped?

 

[Fred@BTM]

from memory you have about 6mm between the bores on a stock block which isn't much!

 

[Icarus]

Why do you want to increase the bore size? An extra 60CC in the real world with mostly stock bits above it will do very little.

 

[Fred@BTM]

what was it you said to me the other week matt? something about sqeazing and banging harder? i forgot to make a note

 

[Chris205]

Well its engine failure and one of the pistons has been damaged so thinking it will have to be bored out slightly. Have been told by someone that the F4R bottom end doesnt take kindly to being opened up that's all, so want to be certain it's the right thing to do and it will be reliable

 

[Fred@BTM]

wwait ANOTHER engine? or the same one?

 

[Chris205]

wwait ANOTHER engine? or the same one?

The second engine Fred.

 

[Fred@BTM]

i assume you're using someone else for the work now then?

 

[Icarus]

what was it you said to me the other week matt? something about sqeazing and banging harder? i forgot to make a note

More squeeze with cams to suit is generally good. Larger bore needs carful consideration due to affects in burn rate across the chamber i.e. more area, longer burn time, less complete burn likely at higher RPM. 84mm is too small a difference to really bother doing the math on though, when you get to high 90mm bore sizes and 18K RPM odd then it gets a bit more critical

 

[Fred@BTM]

you missed my joke completley

 

[Icarus]

you missed my joke completley

No no I got it, just the usual deadpan'ness

 

[Chris205]

i assume you're using someone else for the work now then?

You best believe it lol lesson well and truely learnt. It's going to a propper Engineering place who specialise in building competition engines etc so it should be in safe hands. We've had plenty of work done off the company in the past and they've been spot on. I'm going to scrap the standard crank pulley set up as well as I don't trust them

 

[Fred@BTM]

nothing wrong with the stock pulley on a stock engine, hope you new "specialist" has the tools and experience of F4R's!

 

[Icarus]

Exactly, stock pulley works fine and is working fine on 500,000 odd F4Rs worldwide! For use over 8000RPM we keyway them but that's only because for those revs the valve train load is much higher which takes it outside of Renault spec.

 

[Chris205]

I'm going to use the meg 225 set up anyway, the safer the better tbh and one day it might get boosted if I feel stupid enough to put a few more grand into it

 

[sideways danny]

I dont see the big issue with floating pulleys really. Just requires correct tightening.

Going back to re-boring for a second, it's generally good practice to start with a brand new bore, so stepping up from 82.7mm to 83mm would be what i would do. I've put together a few engines with 84mm bores and they're still healthy and strong, but I dont believe the extra cc gave any measurable gain. 83mm gives you the best all round of a new bore, and not thinning the cylinder walls. IMO anyway