Power

24 hours, you've got to be kidding... I don't remember any of the WM cars lasting more than about 4 hours...

Though very fast down the Mulsanne straight!

24 hours, you've got to be kidding... I don't remember any of the WM cars lasting more than about 4 hours...

Though very fast down the Mulsanne straight!

405kph, if revved to 8500...

what cams are you fitting in the twin turbo ie what lift duration

Who told you that about the cranks, they are bespoke forged oddfire cranks..

Kevin Did. Are you talking about the WM engine or the Venturi 600LM engine - that did run a bespoke even fire steel crank

Who told you that about the cranks, they are bespoke forged oddfire cranks..

Kevin Did. Are you talking about the WM engine or the Venturi 600LM engine - that did run a bespoke even fire steel crank

No, the WM. Three different companies made forged cranks for them (DMC)

[stephendell]

He OWNS one of the WM LeMans engines, but as far as I know, has never run it.

Any idea which one?

They ran a PRV atmo in the WM P76

Then turbos from WM P77 up to the WM P88 & P489

The WM P88 used a reputed 950bhp max output Peugeot ZNS4-WM V6 engine.

I'll probably post a WM engine page up shortly as it's all part of the PRV history but need to double check some of the facts first and collect a few more photos.

Any contributions welcome!

Best off just ringing him and asking. I know it' s a twin turbo 24v odd-fire with bespoke gear driven twin cam heads.

[stephendell]

Here's a road legal PRV racer with a claimed 700bhp + on the dyno

http://www.belgoexports.com/_FR/&03_fic ... d_car=130#

Hmm, see I have a alot of data on the ZNS4-WM, and none of it says they were twin cam (as they used factory pulleys and timing gear) and a standard timing cover (but in magnesium)

The heads are not wide enough for two cams, even with direct to valve actuation, and the pictures I have of the last engine certainly don't look like DOHC...

Here's a road legal PRV racer with a claimed 700bhp + on the dyno

http://www.belgoexports.com/_FR/&03_fic ... d_car=130#

Probably correct. If you go by the size of the restrictors listed, two 36mm ones are good for about 550bhp, which is close to what it had...

[stephendell]

This is the only spec I have:

WM-Peugeot P87/88 'Objectif400'(Gr.C1-1988)
　Peugeot ZNS4-WM 90deg V6 93.0mm*73.0mm/2973.8cc(Twin Garrett turbochargers)
DOHC 910bhp(2.8bar) 8200rpm 122kg

Apparently it was built on a Peugeot 604 bottom end with production crankcase, block, crankshaft and rods. Pistons and heads were non standard. But that's all just hearsay...

lol, I should have read my own notes, they were DOHC, in the last generation...

In 1977 it started off as a production engine (2.7). It had a single turbo running a KKK blower and K-Jet fueling. In 79, they ditched the K-Jet and switched to Kugelfisher mechanical and WM designed their own 4 valve heads (not dohc - designed by Meunier (the M in WM)

The engine was still based on a production 4 bearing block. but Peugeot pioneered the side bolting of the main bearing caps to prevent any cracking. Federal Mogul produced all the engine blocks and castings for Pug, Renault and Volvo (the Espace block is actually from Pug), but WM gradually phased in their own pistons, rods, cranks. Each piston also had an oil spray to the base. The new 4 valve head was produced outside of Peugeot, but retained the normal production chain drive system as we have on our normal PRVs

In '79, they saw 500bhp running 1.2bar of boost on a 2.7 4 valve engine.

Later on they revised the rocker covers, front casing which allowed the enigne to run fully stressed and took the bore up to 91mm with the 73mm crank which brought the capacity up to 2849cc. 223mph was acheived in this guise, running Garrett twin turbochargers.

In 1983, engine development was pushed over to Dennis Mathiot Competition, who introduced electronic efi control to the Kugel injection cam to allow it to be responsive to boost, throttle and revs (like VVT now - but still really primative) Race power was 600bhp at 7000rpm and 62m/kg at 6000rpm.

In 84, this car ran 227mph, in 85 they raised the compression and used oi gallery pistons and pushed over 600bhp

WM had planned for 400kph (250mph plus) in the P87 car running twin KKK blowers again, 8200rpm redline and 1.6bar of boost and 850bhp.

1988, At 1.8 bar of boost it saw 910bhp with 93mm bore and 3000cc. This engine was still built on a factory fresh block from Federal Mogul, ie bog standard as we get today. This made it very cheap to use and had no further modifications to it. All the engines ran standard factory cast liners, but machined to WM specs, and side bolted main caps again. It had a light alloy dry sump and magnesium cam covers and the same bespoke heads, now twin cam with the seperate tappet block.

WM replaced the steel iron crankshaft with its own forged odd fire version. Several companies produced forged crankshafts for WM. The production stroke was retained but concentrated on balanced web design (not t'internet )

The oddfiring nature was unchanged, and it was run as two 3 cyl engines with twin Motronic MP1.2 management per bank, twin injectors per cylinder, and each bank having its own water and oil circuits. Ignition was normal Bosch CD with a seperate dizzy per bank running to 10mm Champion plugs.

The crank was run without any type of balancer shaft with a usual steel flywheel with starter gear and 7 bolt fixing. The crankpins were larger than standard and carried WMs bespoke I-beam forged rods, turning oil gallery fed pistons (Mahle Forged) with base squirters and chrome plated Goetz top piston rings. The pistons had traditional gudgeon pin fittings.

Between the front main cover and the engine was the tradition 3 sproket arangement as found on the production PRV, one to each head, the other to a scavenge oil pump which is mounted on the outside of the cover (unlike inside) The crank nose also went through the cover to provide drive for the alternator (sat in the middle of the V), the water pumps. There were 4 pickups for oil pumping, one for each head externally and one for each turbo.

The combustion chambers were tradition pent roof type, valves at 31 degrees to the vertical. Special valve seats, Nimonic valves (I don't know the diameter, most likely 33/28.), dual springs on steel buckets with normal shim adjustment. The heads had the usual 8 bolts, and the twin pulleys were single gear fed so they could use the traditional production change drive setup.

Throttle setup was before the compressors of the turbos, compression ratio was 6.5:1 and 1.8 bar maximum boost where the max made was 910bhp. Race boost was 1.3-1.4 bar (around 700bhp and a lower rev limit - 7500rpm)

Some engines revved to 8200, another to 8500. Drivers were asked to keep to 7500, unless going for the 400kph run..

So it would be fair to say that 300 horsepower is the most anyone has regarding street legal GTA's, 610's in the UK? What is the reason that most do not take it any further, is it due to lack of funds/dedication or is the scene very much based around reliability?

What happened to the the GTA race series cars, does anyone in the UK own/race one. They obviously have the potential to make 500bhp on the road- what are the weak points of the PRV by design?

The problem in the GTA is the ancillaries restrict the power to around 300. The throttle is small, the intercooler is pretty restrictive and the air has to go through some nasty turns.

Others say it's exhaust related. I personally think a better downpipe is number 1, then intake pipework. But until either is done properly by someone, nobody really knows for sure.

The PRV's weakest point is that it's only a SOHC engine. Internally it's fairly bomb-proof, but getting the air in and the exhaust out represents the biggest problem. Once you near 350, you have to start worrying about the gearbox anyway, and having been in Tony's, I think it's fair to say 300 is anough......!

What the PRV lacks in out-and-out power, it makes up for in torque by the shedload. And torque = accelleration.

Others say it's exhaust related. I personally think a better downpipe is number 1, then intake pipework. But until either is done properly by someone, nobody really knows for sure.

.

Theres where somebody like me comes in as I tried various downpipe diameters and lengths on my GTA with lots of dyno time, and it made no difference. It gained when losing the silencing, but the downpipe made no difference.

We know its the manifolds that cause the restriction as with the factory setup at 1 bar nearly 300 bhp has been seen, yet with the same boost biturbod, 400 has been seen. End of the day both the diameter area of the manifold pipes is smaller than the downpipe diameter, so that is not a restriction.

Martin thinks the throttle is a problem which is silly as SR20 DETs, Cosworth YBs acheive 400bhp on the same size intake, even C1J Renault 5s have hit nearly 300bhp with a 27mm throttle venturi.