Engine Rebuild Options (Mike, James & Chip & Techy People, Advice appreciated)

[-J-]

So… I’ve been told that my Cups engine is down on compression on number 4 and as a result its down on power to 172BHP rather than the 193BHP odd it was making (I think that’s what Mike said) and that it could be a number of things –

Cracked Piston
Piston Rings
Stuck Valve

I am still using the car daily but its running rough as you would expect with hesitation, cutting out at low revs and poor starting.

The car is running an RS2 Inlet and I don’t really have any plans for Boost so I guess really I am looking to get the engine rebuilt to optimise the RS2 inlet.

Is it worth forging the Engine?
Is it worth fiddling with Compression ratios?
Should I just get the engine rebuilt to ‘standard spec?’

Chances are I will get Mike to build the engine for me as he is local(ish) and does my other bits and bob’s on the car, although for Ideas I did notice this although it does not look like Valves are replaced so I guess I would have to factor in extra cost for a set of Supertech Valves and Springs? –

http://www.engine-dynamics.com/EngineDynamicsBuilds/pid100235/cid298/ClioSportEngineBuildLevel1.asp

I have no idea about the company though.

Really I am looking to get anything worth doing to make the engine as reliable as possible whilst optimising the RS2.

What sort of timescales are realistic for an engine rebuild? Is 2 weeks reasonable?

I have thought long and hard about, selling up, breaking, PX’ing the car in standard form for a new car etc but with my future plans the best option for me is to rebuild and ensure the car is reliable long term.

 

[Dan@SJM]

J, moynes is selling my old 197'd and ARP'd engine for £400. Did 200bhp on my rs2

Chuck that in and build up a high comp motor in due course.

 

[Cub.]

If J doesn't want your old engine Dan, can you send me a link / contact details for the seller please

 

[-J-]

J, moynes is selling my old 197'd and ARP'd engine for £400. Did 200bhp on my rs2

Chuck that in and build up a high comp motor in due course.

I did think about a used engine, but it comes with potential issues, who's to say if I buy used drop it in I won't have the same situation.

Cheap option but unknown factors come with it and further unknown cost.

I've got 197 cams sat at home as well but Chip / Mike advised not much point with mikes new timing changes over standard cams.

 

[Djw John]

Dmallet is selling a cracking engine as well

 

[Martin.]

I did think about a used engine, but it comes with potential issues, who's to say if I buy used drop it in I won't have the same situation.

Cheap option but unknown factors come with it and further unknown cost. .

This was my concern when considering a spare engine.

Thought it would just be better to put together the extra outlay, knowing I had a perfect engine going in.

 

[-J-]

Just to confirm, I won't be buying a used engine.

 

[Djw John]

Fair enough, I suggested dans as it has good, documented history from 519 rather than just some random one.

 

[Chip-mk1]

The problem with a forged engine is that the pistons dont like cold starts, if you could get some 12.8:1 piston in there then I am absolutely sure from a performance point of view it would be an advantage, but I'd expect to have to rebuild it every year or two if in daily use.

And the other issue, is if you are spending money on the bottom end, you will be needing supertech valves really to avoid a valve killing your expensive bottom end, and hence its going to get expensive quite quickly.

For a daily driver, I reckon a secondhand engine makes best economic sense therefore.

 

[-J-]

The problem with a forged engine is that the pistons dont like cold starts, if you could get some 12.8:1 piston in there then I am absolutely sure from a performance point of view it would be an advantage, but I'd expect to have to rebuild it every year or two if in daily use.

And the other issue, is if you are spending money on the bottom end, you will be needing supertech valves really to avoid a valve killing your expensive bottom end, and hence its going to get expensive quite quickly.

For a daily driver, I reckon a secondhand engine makes best economic sense therefore.

So basically don't bother with a forged lump, just a fresh standard one with ARP's fresh valves and springs and piston rings.

Swap pistons (if indeed it is a crack) for new standard ones.

Will be a daily driver but in it for the long hall (House purchase on the horizon hopefully)

Would rather a fresh rebuild rather than risk used lump which potentially would fail in near future.

Current lump only has 73k on it so by no means tired.

Not really looking at economic short term repair, rather long term economy.

 

[Chip-mk1]

Forged pistons in a road car generally means 20K miles and rebuild it.

Great for taking punishment but not great for cold starts etc.

 

[MG cup]

I think the key point is anything race derived or uprated has a shorter life, spend some money on better cams and fasteners and abuse it.

 

[-J-]

I'm not interested in adding to spec of the engine as such (eg cans etc). The ONLY reason for the rebuild is due to compression issues.

My thinking was if there are improvements to be made during rebuild for performance and reliability I may as well get them done.

From the above it sounds like my best bet is to simply rebuild the engine with all new OE Renault parts

 

[Rubicon_]

Out of interest why do forged pistons etc require a engine rebuild after say 20k miles?

 

[Chip-mk1]

Out of interest why do forged pistons etc require a engine rebuild after say 20k miles?

Because they expand more than standard pistons, hence they have to be fitted looser than standard pistons, which means when cold they wear against the bore as they tip over more.

It depends on use in terms of how far they will go, if you start them from cold and drive 1000 miles, im sure you could do that hundreds of times without a problem and hence get ten times that mileage no drama at all, but if starting and only using a few miles at a time, thats where you get the biggest issues.

I think about 50K is the most I know of anyone getting out of a set of forged pistons before needing a rebuild, which was a mate of mine who never did less than about 40 miles every time he started it.

 

[Chip-mk1]

I'm not interested in adding to spec of the engine as such (eg cans etc). The ONLY reason for the rebuild is due to compression issues.

My thinking was if there are improvements to be made during rebuild for performance and reliability I may as well get them done.

From the above it sounds like my best bet is to simply rebuild the engine with all new OE Renault parts

Brace yourself when pricing up oversize OE pistons (for it to last a long time its not good really putting new pistons in old bores, although I'd consider it on an F4R just as they are particular good at not wearing the bores compared to say an XE)

Realistically if you are staying OE, I would just chance a set of secondhand pistons and new rings TBH, engine doesnt even need to come out of the car for that (can be honest in situ) so keeps costs lower.

 

[-J-]

I'm expecting at least a few thou for rebuild, I'm waiting on James to cost it up for me with a view to getting the car in early Oct.

May consider other 'improvements' for the build but it seems on a daily driver I'll be limited on what spec will work long term without needing regular strip downs and rebuilds.

Is head work worth considering with the RS2

 

[Chip-mk1]

I dont know of anyone who has done headwork with the RS2, but I would think it might help a little.

 

[Mr R.]

P1 TOM has had his head done and supertec valves fitted by Andrew @ ALD in Leeds.

The porting was £300 I belive.

There is picture s of the head being done on tom's thread.

 

[sonny172cup]

sounds like you was in the same boat as me, in the end I went for a second hand low mileage 182 lump with added ARP rod bolts. I will be adding single piece valves and keeping it as that.

My old lump I am thinking of up rating over a course of time, so I can add to it when funds permit. (might be an idea).

 

[Cupman29]

I'm expecting at least a few thou for rebuild, I'm waiting on James to cost it up for me with a view to getting the car in early Oct.

May consider other 'improvements' for the build but it seems on a daily driver I'll be limited on what spec will work long term without needing regular strip downs and rebuilds.

Is head work worth considering with the RS2

Spending a few grand on a standard engine seems daft to me. you could have many second hand engines for that.

I would get one with decent history and take the chance. Of course, its up to you but that's my opinion.

 

[-J-]

Spending a few grand on a standard engine seems daft to me. you could have many second hand engines for that.

I would get one with decent history and take the chance. Of course, its up to you but that's my opinion.

Yes you could, but you have the added labour for engines in and out, added ball ache of the car being off the road etc etc

I'm in a position where I need a car daily that's reasonably reliable and cheap to run, 2nd hand engines are a false economy long term in my eyes.

Same could be said when I had gearbox issues but rather than risk a second hand one I bought new from Renault.

 

[Dan@SJM]

New set of rings is like £200 retail for genuine ones, ARP's and head gasket set and bolts is about £300. That's excluding fluids and extras like valves. Plus machine work etc

 

[-J-]

New set of rings is like £200 retail for genuine ones, ARP's and head gasket set and bolts is about £300. That's excluding fluids and extras like valves. Plus machine work etc

Not to bad then, will start pricing stuff up.

 

[lemonnobby]

j fair play to you mate. i would be the same.

 

[Fred@BTM]

New set of rings is like £200 retail for genuine ones, ARP's and head gasket set and bolts is about £300. That's excluding fluids and extras like valves. Plus machine work etc

where the hell do you shop? Gold Plated Car Parts?

rings are £100
Arps £85
head bolts £30
head gasket £55

 

[Dan@SJM]

where the hell do you shop? Gold Plated Car Parts?

rings are £100
Arps £85
head bolts £30
head gasket £55

Prices from Adam last week...

Even at trade price, rings are £36/cylinder.

 

[Chip-mk1]

Spending a few grand on a standard engine seems daft to me. you could have many second hand engines for that.

I would get one with decent history and take the chance. Of course, its up to you but that's my opinion.

fine if you put engines in and out yourself but second hand engine supplied and fitted with fluids etc is going to be upwards of a grand a time at a specialist.

 

[Fred@BTM]

Prices from Adam last week...

Even at trade price, rings are £36/cylinder.

£25 each from my man!

 

[Dan@SJM]

Wish you'd for me that last week.

 

[Andyman]

Forged pistons in a road car generally means 20K miles and rebuild it.

Great for taking punishment but not great for cold starts etc.

I asked my engeneering place regards to this business of forged pistons only lasting 20k area. He said they should last far more miles than that, quoting car manufacturers who use forged pistons as standard in their engines.

 

[Chip-mk1]

I asked my engeneering place regards to this business of forged pistons only lasting 20k area. He said they should last far more miles than that, quoting car manufacturers who use forged pistons as standard in their engines.

Get the list of people that he quoted who use forged pistons in their engine, go and look up the grade of ally that they use, especially in terms of things like how much silicon is in it, and then compare it to small volume aftermarket forged pistons like the ones available for the F4R, and you'll find as a result of the difference in composition the standard ones have a smaller thermal expansion rate, which is what allows them to last longer than aftermarket ones.

 

[Cupman29]

I know loads in the Subaru world with forged pistons lasting way longer than 20k but haven't checked the silicone content I must admit.

All sti Subaru's had forged pistons up to V6 I recently found out.

 

[Chip-mk1]

Cosworth YB standard pistons are forged and last 150K miles no drama at all, same for the pistons in the early vauxhall XE engines, both made by mahle, but they dont seem to be the same material or process as aftermarket ones like Wossener or Omega etc which IME never last as long.

Im not saying its impossible to ever get more than 20K miles as even on aftermarket pistons it does happen, but im just trying to prepare people for the fact that if you build an F4R with forged pistons, it wont last as long as if you build one with cast pistons which can be run on tighter tolerances, ie in terms of lasting as many miles as possible with moderate load they are a downgrade not an upgrade.

 

[bartebk]

After reading this I'm thinking of not bothering with forged pistons!

 

[jay70]

I know loads in the Subaru world with forged pistons lasting way longer than 20k but haven't checked the silicone content I must admit.

All sti Subaru's had forged pistons up to V6 I recently found out.

The STI used them up to V7 although they are not like aftermarket forged pistons. From V8 they change to a hypereutectic piston on the 2.0 which run a tighter tolerance.....My old forged built Subaru engined sounded like a diesel until it warmed up.

 

[Chip-mk1]

-J- you never did update this thread to tell people what route you went down.

for you use I think you made a good choice

 

[-J-]

True... I took Chip-mk1 advice and went for a standard lump rather than rebuild I purchased a new engine.

The car is 80% a fun road car and TBH looking further at forging the engine the costs Vs benefit really didn't add up.

Had I been looking at the boosted route then I may have gone forged, but for NA 200ish BHP it seemed over kill.

Only thing I'll probably look to do beyond the standard spec is add some ARP's at some stage.

 

[Mr R.]

A new complete engine from Renault?

 

[-J-]

A new complete engine from Renault?

Yep