The good old days ?

No argument here but it's not the be all and end all of the inherent problems ...but hey what do Martin and I know ..after all we've only gone and built half a dozen lumps in various guises .

I dunno ...you lot are just so easily led ....feck ya all !! I will not say another word till JIL blasts ya tits off

Lee, count me in.
I just love a good blast on tits
Really looking forward to the success.

As we all know I know nothing about these things but a question for you both:

Are there other manifolds that exist from other PRV applications with better flow?

Probably not but worth an ask

Yeah, use a pair of aftermarket Atmo 3-1 manifolds, and put the turbo down low at the front of the engine, like on a Porsche 911. Keep the engine bay cooler down there too.

Heres a car with a V6 that does that...





....and its a Renault.


Like this but instead of two turbos, put a link pipe between the two manifolds with a turbo flange on it



It makes me laugh, that if someone was tuning an Atmo, they would buy those manifolds without question - look at the size of the flow, and those are what you need if you want only 200bhp....

....Yet, when it comes to a turbo, and dreams of 350bhp, some people think the pencil dicked '3 straight into 1' within 2" of coming out of the head manifolds are perfectly fine

So why one larger turbo rather than the two smaller ones Dave?
is it a single large turbo pumps more ultimately where as the current road car trend ( or atlantique) of two or even three turbos gives less lag and less ultimate power?
Lee

So why one larger turbo rather than the two smaller ones Dave?
is it a single large turbo pumps more ultimately where as the current road car trend ( or atlantique) of two or even three turbos gives less lag and less ultimate power?
Lee

Two turbos are always better that one on a V engine, hence why later that Renault turbo engine went to two turbos.

On that single turbo setup it will be laggy - and some of the method in the madness why Renault put small bore pipes on the GTA.

The only benefit of putting a big single turbo on is cost, and ease of plumbing, and setting up. Two turbos means two intercoolers (or CC's), Y plumbing into a single throttle body - making sure one turbo isnt making more boost that the other (nigh on impossible to check on a single throttle body system) Costs will be doubled, at least, and lots more work.

Here it is in twin turbo guise...



And here are some more single turbo setups















This is the beauty of the GTA engine bay - once you ditch the rear silencer, you have lots of room to put a turbo in front of the engine, or even more if you offset it to one side.

Nice pics... anyway, 'ave you guys got too much spare time on your hands??

Look away for 5 mins and the thread has grown legs, and hairy at that

[BIG_MVS]

The manifolds are definitely the issue, i thought we all new that.

Never mind all this engine tosh...Back to school Tony - You needed a capital I and a k is missing in front of the new. Back of the net

Something I just remembered, and more real world evidence..

Has any one noticed (or paid attention to the fact) that all the GTA's running the 0.36 (Standard) turbo exhaust housing make around 230bhp max, yet all the cars running the 0.48 turbo exhaust housings are the ones that can make 260..PeterG, Steve, Prima, Politecnic...

Tony is running a 0.63 housing (same as original A610) and makes 300..

Now a .48 is good enough for 320bhp, and a 0.63 good enough for about 370, but on the Alpines you still have a 2" downpipe outlet to cope with, so this basically knocks both down to about 300 again...

So basically, decent 3 into 1 manifolds, a GT32 or GT30 turbo with a 2.75" or 3" outlet, and a 3" downpipe. All on a standard engine - you will see over 300bhp.

Its all very well mentioning cams and heads, and yes they are crap on this engine, but as many different engines have shown, you 'can' get around this with more boost - but you can't get round it with boost, if your exhaust backpressure is higher than your inlet pressure.

I really hope that Lee and Martin get some great power because they deserve it with all the effort they have put in. But I think what Dave G (good to have you back by the way) is saying is there is only so much polishing can be done to a turd and while pretty much any engine can produce good power if enough time and money is thrown at it if you look at other turbo engines they make much higher specific output for given boost. i.e 2.5 PRV at 1 bar on standard turbo makes about 85bhp a litre, compare that to some other turbo engines of the time - 2.0 Cossie , Nissan GTiR, Skyline GTR all make around 140bhp litre at 1 bar, Toyota GT4, Impreza, 300zx, all make 120-130 bhp a litre at a bar. Alot of this is to do with turbo sizing, and installation in the cars but when I talked about the 3.0 litre being a better engine than the 2.5 I meant in a standardish spec not what the potential of the engine was or the quality of the materials used in it. I drove a modded 2.5 running 240ish bhp for 10 years remember so I'm well placed to judge, in comparison the 3.0 is smoother, less laggy, much faster obviously, revs much better, has a power band more suited to a sports car, is no worse on fuel. I can honestly say I can't think of 1 thing better about the 2.5 as an engine to drive behind. From an engineering or design pov it may not be better but does that really matter if your not building an engine to nowhere near its optimum spec?

I think the main thing you can't argue with and some people are choosing to ignore, is Renault themselves have proved its the exhaust system on the GTA/610 that is the issue.

You have an A610, and Safrane Biturbo. Both engines are identical, same cams, heads, pistons, everything.

Yet one makes 250bhp at 11psi, and the other makes 270bhp at only 7psi.

As an n/a 3.0 does 170bhp, you could say crudely say that on a 610 every psi is worth 7bhp, yet on the Safrane its 15bhp on their standard power levels. And it documented that the Safrane was set at that power because the transverse gearbox can't handle anymore.

It makes no odds on having two compressor wheels v's one on the 610, as both are still flowing air through a single throttle body, so the only difference is the exhaust side.

Fact.

I thought you'd enjoy this

Safrane Biturbo produces 258bhp (262ps) at 8psi (1550mB abs). Figures from the Renault manual.

Safrane Biturbo produces 270 ft-lbs (366Nm) at 2500.
Venturi 300 produces 309 ft-lbs (420Nm) at 2500 (1 bar boost on an A610 engine)

Its weird that most english worded webpages list the car at 262ps (258bhp), yet all of the French pages say 268ch/cv (268bhp)

At it makes peak power at 5500rpm, which is 21.7 millibars, which is 7psi

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