The good old days ?

Feck-me Tony ,that's looking the business All done ? ready to map ? Best get a wriggle on

[stephendell]

Out of interest whats the diameter of the manifolds on an A610 as opposed to a GTA

They are exactly the same. Equally rubbish.

WOW....where did you get that wall paper from

There you go, thats how you do it....

Getting there but the proof is in the pudding..

There you go, thats how you do it

Thats perfect really, the only downside (and don't think of this as a negative) is Tony has also modified his engine too. Id like to see this setup on a completely standard 2.5 engine, (obv need an ecu mod, injectors) to make a good comparison from all the normal cars.

[mettersl]

Tony- are the manifolds standard size on this (by the heads, clearly not later)?

Lee

blah blah ....

3 litre 12v Biturbo PRV ..... 550 bhp, ran at Le Mans in a Renault factory supported..... what's all the kerfuffle about

blah blah ....

3 litre 12v Biturbo PRV ..... 550 bhp, ran at Le Mans in a Renault factory supported..... what's all the kerfuffle about

Well done Andy...thats what most of this discussion was about...

Tony- are the manifolds standard size on this (by the heads, clearly not later)?

Lee

I think they are aftermarket atmo manifolds like the ones I said.

When I talk about the 'manifolds being crap' on the GTA, I don't just mean the manifold - I include the whole system before the turbo in that statement (and the exhaust turbine housing the downpipe outlet size is bad too) but thats another issue...

blah blah ....

3 litre 12v Biturbo PRV ..... 550 bhp, ran at Le Mans in a Renault factory supported..... what's all the kerfuffle about

Well done Andy...thats what most of this discussion was about...

if any one wants one..... we can get one built in a couple of weeks or so.... most of the parts are lying around in mine and Antoines garages

just a matter of ££££€€€€,

Bespoke manifolds,to match reworked heads.

Thats perfect really, the only downside (and don't think of this as a negative) is Tony has also modified his engine too. Id like to see this setup on a completely standard 2.5 engine, (obv need an ecu mod, injectors) to make a good comparison from all the normal cars.

Well I think it is still a fair comparison. The BMEP performance / ability of the engine (given the OE 2.5ltr capacity and piston is retained) is pretty much determined by the port time-area, and significantly more the inlet at that, and in this case the OE valves and 30 deg seats on the inlet have been retained. The cam in Tony’s engine is a reasonable upgrade, but certainly not race spec, hence the ability of the engine to perform as an air pump is reasonable comparison to OE; certainly to a spec the factory could have shipped originally if they so wished – pity I think.

However, more significantly the better collectors and merge header to the turbo, and indeed the turbo are going to combine to greatly reduce the back-pressure, and hence have a far greater impact on performance of the package and should show some good beans...

This is a nice build, and hope Tony gets the results he’s looking for, certainly John has put this together with a great deal of care…. about time you put this in the project section Tony with some more pics!

C'mon Tony ,stop being so shy .Post up a few more pics and some info .
I dunno ...you Southern lot all like to keep it close to your chest ?? Is it because you don't want to look foolish in front of DG ??
It's OK , we Northerners don't care .we will always think you're all caaaaants

Thats perfect really, the only downside (and don't think of this as a negative) is Tony has also modified his engine too. Id like to see this setup on a completely standard 2.5 engine, (obv need an ecu mod, injectors) to make a good comparison from all the normal cars.

Well I think it is still a fair comparison. The BMEP performance / ability of the engine (given the OE 2.5ltr capacity and piston is retained) is pretty much determined by the port time-area, and significantly more the inlet at that, and in this case the OE valves and 30 deg seats on the inlet have been retained. The cam in Tony’s engine is a reasonable upgrade, but certainly not race spec, hence the ability of the engine to perform as an air pump is reasonable comparison to OE; certainly to a spec the factory could have shipped originally if they so wished – pity I think.

However, more significantly the better collectors and merge header to the turbo, and indeed the turbo are going to combine to greatly reduce the back-pressure, and hence have a far greater impact on performance of the package and should show some good beans...

This is a nice build, and hope Tony gets the results he’s looking for, certainly John has put this together with a great deal of care…. about time you put this in the project section Tony with some more pics!

There is method in Renaults madness about the original cam profile. Like I mentioned before, Politecnic France did a 2.5 GTA with a 260 degree cam, and it made peak torque at 4000, at running a bar of boost it made less torque at 2500 than a standard GTA turbo... and the restrictive manifolds made the power cap off at still 5k - Seeing as all the other PRVs had better breathing cams as standard, you can see Renault specifically used the turbo profile cam for a reason, to boost low end torque instead of having a usable power range of under 1000rpm. I look at the GTA turbo as how you would pretty much design a diesel turbo engine. You know its not going to rev, so you need to make the best of what you have down low.

Regarding Tony's cam, its still not a fair comparison to standard, as no-one has yet done this type of good turbo/manifold conversion as standard, so say the car makes for instance 350bhp at moderate boost, we won't know if 60bhp of it is cam....but on the flip side, even on a standard engine, once you have a decent turbo manifold, turbo etc, and that is no longer a restriction, you can always simply increase the boost within reason to compensate. You may find an uncammed example could make the same power with 5lb's of more boost, and may even make more torque, but then natural efficiency within reason is always better than running more boost.

Also, changing the cam will have changed his BMEP, by the change in dynamic compression ratio.

you can't get round it with boost, if your exhaust backpressure is higher than your inlet pressure.

Forgot about the Venturi - Another example of a 3.0 with a bigger turbo and making sub 300 at almost a bar of boost.

Venturi 300 is an off-the-shelf A610 engine running higher fuel pressure , 1 bar boost and a slightly tweaked map. Everything else is the same

More boost equals less lag, so if you wind the boost up on most turbo cars it will reduce lag, it may have a more pronounced step as it comes on boost so the lag seems more pronounced but the time to get on boost will still be less.

It's chicken and egg though, not egg and chicken.