V6 Clio engine blown

[CB1A]

Ahhhh, the joys of nitrous. (Running at 380bhp) - Piston ring meltdown and stuck to cylinder wall.

http://members.lycos.co.uk/jamesavy/P8200002.JPGhttp://members.lycos.co.uk/jamesavy/P8200002.JPG

http://members.lycos.co.uk/jamesavy/P8200004.JPGhttp://members.lycos.co.uk/jamesavy/P8200004.JPG

http://members.lycos.co.uk/jamesavy/P8200005.JPGhttp://members.lycos.co.uk/jamesavy/P8200005.JPG

http://members.lycos.co.uk/jamesavy/P8200007.JPGhttp://members.lycos.co.uk/jamesavy/P8200007.JPG

http://members.lycos.co.uk/jamesavy/P8200008.JPGhttp://members.lycos.co.uk/jamesavy/P8200008.JPG

http://members.lycos.co.uk/jamesavy/P8200010.JPGhttp://members.lycos.co.uk/jamesavy/P8200010.JPG

 

[m@thew]

damn thats bad luck, hope its all up and running again soon

 

[paddymph]

doh?! fixable?

 

[rockport]

 

[CB1A]

damn right fixable - me and my mate are going to re-build it with a few mods (forged pistons etc) will be ready for york dragway on 14 sept

 

[Slugger]

oops

 

[BenR]

lol!

thats excellent mate, hope you had fun doing it anda bit of a giggle after.

Whenever we blow an engine we are rolling on the floor after.

But it looks like a fueling problem caused it.....nowt to do with the pistons not being up to it.

How much that gonna set you back!

 

[paddymph]

hahahahaaaaaaaaaaaaaaaaaaaaaaa. LMFAO!

only BenR could look at that and say thats excellent mate!

Only on Cliosport

 

[BenR]

lol, ive blown and seized too may engine when messing about, so i know it can be a right laugh....we actually built and spent a week modding a golf engine once to see how far we could get before blowing it BIG stylee....lasted about 4 days too, but used about 4ltrs of water every 10 miles lol.

CR of 14.5:1 lol

 

[CB1A]

the problem was down to the fuel pump ( with the increase in hp it was insufficiently supplying fuel ) - the cylinder that went was no 6 which is the furthest away from the fuel rail. Im ordering some forged pistons and an increased fuel pressure valve for the pump. This should cure the problem and along with a 200 hp jet it should get me into the 11 - 12 sec qtrs.

 

[BenR]

eh?

how will a higer pressure solve your flow rate suppy problems?

TO double the flow you need to increase the pressure by 4 times through the same oriface.

We used to get vapour lock problems with the non return system on the V6.

 

[CB1A]

spoke to project 254 about this and he has the modified fuel pump kits that renault use on there trophy cars to increase fueling. Ive spoke to a lot of nitrous specialists and sent them pictures of the damage and theyve more or less put it down to what i diagnosed it as originally. I only need another 25 - 30 % increase in supply for the n20 jet i need to run and the kit 254 has will do the trick. Its all taken care of ben.

 

[BenR]

cool cool.........just checking!

 

[philip]

can you explain how insufficient fueling can ruin a piston ring please. My reason for asking is that on an F4R the injectors are good for 52bhp max (208 bhp), optimum at 168 bhp or so. If various modifications take the power to 195-200 or above, could lack of fueling cause a problem such as the one you describe, only a milder form leading to increased blow-by? (to help diagnose, which is the furthest cylinder on the F4R, may be interesting to run a compression check on that and see if its lower than the others) In summary should the injectors be upgraded on a car thats running 200bhp?

how involved is it to replace piston rings (I assume it also depends if the cylinder etc has been damaged and needs a rebore), and does somebody supply uprated pistons for the F4R?

Many thanks, P

 

[Roamer]

Philip, insuffient fueling leads to one thing........ a mixture which goes away from stoichiometric toward lean, lean mix causes temperatures to rise, which causes the lean fuel mix to pre-ignite...... causing damage.

 

[philip]

I would assume that an engine running lean would be detected and corrected during a remap. So theoretically, as the engine is nearing the 208bhp max theoretical injector limit, the mix would be getting leaner, causing temperatures to rise and gradually damaging piston rings, right? does a piston ring get damaged gradually and if so does it lose its sealing capability partially (i.e you get increased blow by) or does it just go pop?

 

[BenR]

Yes, running injectors that cant supply enough will damage your valve (most exhaust) and piston.

In CB1As case, runing nitrous is sensitive, you have to run it spot on or slightly rich. His combustion temps would of increased, i dont think it caused an exhaust valve lip to get extreemly hot or a hotspot on the piston/chamber and the piston since there is no marking and no detonation damage, it just got too hot and expanded in the bore.

When we talk about stoichiometric its refering to the a/f ration which the catalytic converter needs to operate, not peak power a/f ratio as this can change slightly.

The cylinder firthest from the pump in the F4R ic ant remember, but there is only one line with it being non return, just look. The fuel line will join the rail at one end, and at the other is the furthest cylinder, but pressure along this rail will not vary.

The injectors should be upgraded yes.

Have you checked your car on a gas analyser, they will be able to tell you if your engine is burning correctly.

As for damaging a ring, could well do yes, and changing rings is an engine out job basically.

 

[Roamer]

The fuel rail is fed from the offside of the vehicle, so its the cylinder closest to the curb that you would question Philip.

 

[BenR]

cylinder number 4 then, or the one nxt to the flywheel, unless you number them 1-4 from the flywheel lol!

 

[philip]

do you have the compression values per cylinder in bar for the F4R, does 9.25, 10, 10.9, 9.8 for cylinders 1 to 4 (1 being the curb side, i.e furthest from the f/wheel) sound ok?

 

[Roamer]

Sorry, lets go through this again LoL the cylinder on the offside (Cam pull side) is number 1, and therefore the cylinder on the flywheel side is number 4......

I think? LoL

 

[Roamer]

Oh sorry matey I forgot about the compression values, well, I dont know about the official ones, but when running a compression test its said that they should be within 10% of each other

 

[zeemax]

CB1A, any news on the price for that fuel pressure valve? gota get one for mine asap, not running nitrous till I get one. I have the car booked into bhp in Byfleet in 2 weeks time for a set up on the rollers.

 

[Roamer]

Surely if you increase the fuel pressure the standard injectors will be pushing more fuel per opening? so are you having a new ecu or a remap to sort it? or am I wrong?

 

[Tom]

sod that bin the v6!!

lob in a 3.5 litre twin turbo lotus v8 (bound to be one at a scrappy) uses a renault box dont it? cant be that hard

 

[Scudetto]

Im very impressed with Bens technical knowledge. I havent a clue what hes talking about but he seems like a handy chap to have about when theres a fuse that needs replacing

g

 

[Tom]

i still cant find my oil cap?

 

[Scudetto]

its in the kitchen love, just by the fridge.

g

 

[BRUN]

is it just me that those pics wont work for.........?

 

[172nightrider]

NOPE they dont work for me either

 

[STICKER TWONK]

Pics dont work for me either

 

[BenR]

phillip, i cant remmeber the actual spot on compression values, but 10% is about the max varying limit.

Each cylinder should be up to maximum pressure within 3 chugs, anymore and something needs to be checked. Also, pour a teaspoon of oil down the cylinder that is weakest and if it bumps up the max value then you have ring sealing problems, if not and its still low, you can start thinking about valve sealing or head gasket problems..........jsut methods, not saying anything is wrong with yours yet.

Get a leakdown test done.

 

[CB1A]

its a new engine - stripped it today and 2 pistons cracked - cyl scored and head damage. 255 hp block mk 2 lined up. With de cat and r -sport ecu should see close to 300 hp. If it dont work im gettin me another corvette.

 

[edde]

How different is the Mk 2 block i would have thought it was the same.

Is the engine the same as fitted to the other V6 cars etc LAguna.

Why not use the Renault Vel Satis 3.5 V6 I would have thought that had more potential or is it weeker as its most likly a bored out 3 liter.

Isnt 300hp a little high an estime to get with so few modifications?

Why not turbo the engine its a 3 litre so with a low pressure turbo it would make loads of power. 500hp would be obtainable with 1 bar I guess with enought work.

Please dont get a corvette there arnt many V6 owners here and none with any real tunning like Nos as you have. the car looks excellent by the way even up on the ramps.

EDD

 

[Mike T]

Mk 2 is the same its the top thats different

Yes

Doesnt fit!

No that would be fine - TWR had 280 before closing down for emmisions and warranty reliabity required by Renault out of the 255 unit

I have supercharged and 400+ BHP at 1 BAR is easy (320bhp at .5 bar is a lot in the Clio (4.5 - 60mph) and very reliable and the torque has to be driven to be believed (20mph - 170mph in top at 7500rpm)

NOS is not real tuning (thatll get the forum active!!) - it improves combustion for ltd periods and without other mods is very risky - as you can see



yours - stirring a hornets nest, Mike

 

[zeemax]

Any idea how much a mk 2 top end would cost? Dan.