Timing.......FAO, MWM, Fred, Chip, 519, Birchdown

[Chip-mk1]

Just to give me an idea if they throw out a crazy number which I think £150 is tbh, thats 2/3's of the way to a remap.

I think you are being a bit hopeful if you expect someone with the correct gear to alter it to get involved in booking it in in the first place for 50 quid or something, so I reckon most people will be in the 100-150 ballpark so I was just giving you a worst case scenario, but like I said its not for me to quote on behalf of others.

 

[MG cup]

Fair enough, it is going in there for MOT, geo and maybe a power run so I hopefully I can get a deal done.

 

[ben_r1]

The vvt on the 197 allows you to map in variable advance, not having that isn't an improvement at all, if yours had it and was mapped properly to use it all it would do is gain you torque, you wouldn't lose anything. Only down side to the vvt is reliability if revving really hard and if using very high lift cams you run the risk of contact if it doesn't operate correctly. Performance wise though its all round win for the vvt

With the 403s I ran it was advisable to delete VVT not to mention with the cam cover laser cut out the exhaust cam can be adjusted in seconds on the dyno. If your keeping the revs above 5k I see little more the VVT can do. Have driven same car with 402s and VVT and 403s with solid pulleys and the power delivery is much much smoother without it. I'm not speculating this is personal experience. Granted its dead under 5k but for a track setup is ideal.

 

[2Damnsly Andy]

So the group N engines ran on standard cams and it's just the advance on the timing that gives them the added performance? Or did I miss something?

 

[Chip-mk1]

With the 403s I ran it was advisable to delete VVT not to mention with the cam cover laser cut out the exhaust cam can be adjusted in seconds on the dyno. If your keeping the revs above 5k I see little more the VVT can do. Have driven same car with 402s and VVT and 403s with solid pulleys and the power delivery is much much smoother without it. I'm not speculating this is personal experience. Granted its dead under 5k but for a track setup is ideal.

Its a variable setup, so with the right mapping could be made to do what yours does now, and then under 5K it could be better.

BUT I do agree that spending that amount of time on mapping it isnt worth it if its a pure track car that never goes under 5K anyway, would be different if it was road legal and driving to and from events etc though, and there are reliability issues with the dephasor too and these only get worse with hotter cams and harder springs etc as the load is increased.

 

[Chip-mk1]

So the group N engines ran on standard cams and it's just the advance on the timing that gives them the added performance? Or did I miss something?

Well its not just that, everything about a group N engine is slightly optimised, even the cams themselves are only the same on paper and in reality are slightly different, but essentially yes mate you are correct, the most signfiicant difference is the cam timing itself.

 

[MG cup]

Group n engines are blue printed if you understand that term, squeezing every last bhp/torque from the car by having tighter machining tolerances than when they left the factory.

Things like cam timing and ECU are played with to give the absolute best performance from Renault parts, they are a compromise for road driving typically, got to keep the engines on the boil a bit more.

 

[Chip-mk1]

Group n engines are blue printed if you understand that term, squeezing every last bhp/torque from the car by having tighter machining tolerances than when they left the factory.

Things like cam timing and ECU are played with to give the absolute best performance from Renault parts, they are a compromise for road driving typically, got to keep the engines on the boil a bit more.

The compromise is on cost as well for the road cars, blueprinting is expensive. If a group N engine is "standard" to the blueprints, then the average road car is substandard to the same, lol

 

[MG cup]

Not quite getting what your at there Chip but yeah it's expensive to blueprint an engine. The best run of parts are usually put aside at factory for things like group n so actual blue printing of the engine hardly takes place but the tolerances throughout the engine are as close to perfect as possible making your typical road engine substandard. Hence why you get that odd car that has freaky power when in reality all the stars have aligned and the tightest tolerance pieces have been bolted together.

If your really anal, you can do a pretty good job of blueprint ing by stripping 3 engines, measuring everything and choosing the best, cheapest way to so it if you have the know how

 

[Chip-mk1]

Not quite getting what your at there Chip but yeah it's expensive to blueprint an engine.

Yes you are:

The best run of parts are usually put aside at factory for things like group n so actual blue printing of the engine hardly takes place but the tolerances throughout the engine are as close to perfect as possible making your typical road engine substandard. Hence why you get that odd car that has freaky power when in reality all the stars have aligned and the tightest tolerance pieces have been bolted together.

Exactly, selective assembly of the parts and then exactly setting the tolerances during build is how the engines COULD have all been made for the road too, but its expensive, Type R honda engines for example though are made "as standard" much more in common with this way.

If your really anal, you can do a pretty good job of blueprint ing by stripping 3 engines, measuring everything and choosing the best, cheapest way to so it if you have the know how AND PLACE NO VALUE ON YOUR TIME

Yes I have a friend who builds a lot of competition engines and one of the series he builds for banned the machining of conrods to balance and lighten them, so now he has to strip 20 engines and pick the lightest 4 conrods that are the closest balance.
So where it used to cost a bit of labour, it now costs a lot and shed loads more money for parts, so the series organisers trying to make the engines cheaper to build by getting rid of "expensive" machining have now replaced it with MUCH more expensive selective assembly, lol.

 

[Andrewclio]

As for the group n engines I've actual got the homologation papers for the car and you won't believe the amount of tolerance there is.
If anybody is interested i can send them a copy to them..but bare in mind most of its in French lol

 

[jon_r]

Does anyone on here have the proper group N tool? I'd love to give it a go on mine just to see what happens. I don't care if it runs as rough as houses on idle either, it rarely gets used.

 

[Chip-mk1]

That's why renault knocked the exhaust cam back a touch, to keep them alive at the top end. That's on the full grp n settings of course.
When mines alive again I will be able to give a report back as to how much it holds on as I've got the full grp n tool and the grp n ecu to match. Assuming people would be interested that is.

Jon, see above.

 

[MG cup]

I poofed out and just set mine to standard timing today, needing it to pass an mot this week so thought it better to be safe, I will give it a try after the mot hopefully with power runs for both on standard inlet.

 

[rich83]

With the 403s I ran it was advisable to delete VVT not to mention with the cam cover laser cut out the exhaust cam can be adjusted in seconds on the dyno. If your keeping the revs above 5k I see little more the VVT can do. Have driven same car with 402s and VVT and 403s with solid pulleys and the power delivery is much much smoother without it. I'm not speculating this is personal experience. Granted its dead under 5k but for a track setup is ideal.

Hi Ben,
Would you mind answering a few questions on your 197 engine, I've got a 403 engine too but making very poor power (~205bhp, I also have pistons and an R3 manifold) and you're about the only other person I've found who's used 403's!

• How much power did you make on 403's?
• What pulleys did you fit on them? - I haven't looked but I was under the impression they didn't have a key for verniers?? I am however kindly being lent a rocker cover that has been properly cut to allow easy cam timing, so I might not need verniers anyway?
• Who did your timing on the cams and do you recal what settings worked? Mines apparently timed to stock at the moment.

Cheers

 

[ben_r1]

Hi mate mine made 230bhp with ITBs and high comp forged pistons in its final setup.

It had CatCam adjustable vernier cam pulleys with a hole cut out of the cover to allow the exhaust cam to be adjusted whilst running. ( as in turn it off, adjust and fire up again. Not actually adjusting it whilst idling ).

Matt at TDF built the engine and mapped it on the dyno but I haven't a clue as to the settings he used and unfortunately he has little interest in RenaultSports these days.

 

[rich83]

Cheers mate, interesting that the vernier's fitted your cams, I was under the impression there was no keyway for them. Trouble is it is not easy to check!
No worries on the timing settings, was a long shot!

I've got a cut up rocker cover here also but that is to allow measuring lift at TDC to set it up, then from there it will have been the verniers that allowed you easy dialing of the cams I think? Otherwise as I understand it you need to untension the belt and slacken off the pulley bolts etc if you want to rotate the cams, regardless of the rocker access.

I 've since spoken to RST though and they have the proper catcams tool so we are just going to use that to make sure the cams are properly timed using a dial guage. I did initialy suggest maybe looking at retarding the exh cam for more overlap but it could make it worse and without the verniers it's just too damn unfeasibly expensive to bugger about testing. So I am going to stick with the corrected default settings which should be a vast improvment over my current settings anyway which are likely quite a bit out from everything I have seen of catcams machining!

If your car had ITB's then it must be the white one thats occasionally mentioned still over on 197! Other than a proper rally car I know it's still the only other mk3 I've seen with ITB's. Hopefully I'll get mine on them before long.

Cheers

 

[ben_r1]

Yes that's the one matey, I do miss her