Booting up the PSA 16 Valve motor.

Alan S

Alan S

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Location
Queensland, Australia
We often hear about the UK spec BX 16 Valve/Mi16 motor having more zap in European form than the Aussie one.
One guy from over there who is a registered member of this board & who has asked questions regarding Cat removal in the past has just posted that he has at last (after about 12 months) found out the difference & what is required to convert to UK specs or in the case of a BX to Mark 1 specs.
Maybe I'm getting a complex but; this is what HE said, NOT ME!! I recently posted a message from another board along with the same type of disclaimer & finished up with everybody basically calling me a tosser based on the other guys comments - maybe they're right - just didn't know how to tell me before :rolleyes: :rolleyes: :p :eek:

Hi folks
Useless info time again! I've been trying to find out what the differences are between my cat-equipped 16V and a non-cat version - and at last I have what I hope will be the definitive answer!!

I got my local main dealer to look into the differences in engine part numbers between 2 chassis numbers - 1 cat 1 non-cat.

I was led to believe that cams and/or pistons could be different and therefore trying to get the full 160BHP out of my engine wasn't possible.

It turns out that the main difference is down to the use of unleaded petrol. The valves are slightly smaller in diameter due to larger valve seats designed to cope with the higher temperatures generated in an unleaded and cat-equipped engine. The ONLY other difference is a different head gasket designed to cope with higher temperatures also.

I therefore can guess why my head gasket is beginning to weap to the outside world (apparently as I haven't seen any evidence myself) since the gasket was changed 3 years ago when the head was rebuilt after the belt snapped. Seems likely that the standard gasket was used by mistake assuming they checked the head was flat before putting it back together!

The good news is therefore that if I'm prepared to fork out for a head job and new valves I can easily get the 'lost' power back and if I opt for cams also a bit more besides. Guess that stainless exhaust will be right near the top of my shopping list after I get married in July!!

I'm now a bit happier about the potential for more power out of the old girl - anybody got a ported head for sale?!

Adrian



:D
 
Sorry guys,
but there are a two very important differences between an XU9J4 and an XU9J4Z.

1. CR
The dirty XU9J4 has 10.4:1 CR by way of lumpier pistons. There is no way of getting an XU9J4Z from 9.5 to 10.4 with a head job. You need the lumpy bits. The low CR pistons have an X on the crown.

2. Valve Timing
The XU9J4Z has the inlet timing retarded by 4 degrees crank, by way of different cam shaft pulley.

These two factors combine to create a "peaky" torque curve in the XU9J4Z, which comes alive at approx. 4000RPM. The XU9J4 has a lot more bottom end torque, and thus has a flatter (and higher), less peaky torque curve.

The heads are otherwise identical. The 89/90 model 405 ran on unleaded or leaded. The CR determined the type of fuel used, not valve seat material.

The XU9J4Z also has a completely different ECU, which has addition of an O2 sensor input. The XU9J4 does not have a sensor, as continued use of leaded petrol would kill it.

Advancing the timing will flatten the torque curve, resulting in better flexibility. There are several ways to do this, but you just can't beat good fuel and good compression. The XU9J4 on 98 octane is a very nice thing to drive.

Happy to fax a copy of the original Peugeot documentation to anyone who's interested.
 
Hi Guys,

running optimax, wouldn't you be able to shave the head (just a little to raise the compresion). Then Alan (with Brads help) should be able to tune his engine more for outright power rather than down low torque, making driving the thing much more like the earlier car. The early one certainly were MUCH quicker than the later cars (couple of seconds + difference in the 0-100km/h sprint).

Possible???

seeya,
Shane L.
 
are we talking about the difference between the series 1's and 2's here
i found that my series one was always all over a series 2 car
it was quicker and revved smoother
especially when you hit about 4500rpm it got a real kick to it
gave a bloke in a 5litre holden a big shock one day in QLD
 
Having had one of each, Aus and Euro Series, I can testify that the latter is heaps quicker. As I said before, it doesn't have that rush at 4-4500 because of it's superior flatter curve. It will hose off most Aus spec 205GTi. The easiest way to improve the smog model is find a spare exhaust pulley and fit it to the inlet. On the XU9J4 they are the same part number.
 
Thought I'd come and check out what Alan's been getting as a response to my post on the BX Forum!

Thanks for the info - one more question though. My engine has a code of 'DFW' stamped on a little plate riveted to the top of the block which I know was used when the fault code memory was read, does this mean anything to anyone ref. XUJ*** type codes?! The head is stamped with 1CWH9 000588 any ideas what that means?

I guess it's possible that there are 2 types of cat-equipped engines depending on the market it was intended for. My car certainly didn't feel stupid slow compared to the much earlier Phase 2's that convoyed to a track day here recently. Most of those also had induction kits and stainless free-flow exhausts so I'd expect to be a little slower.

The dealer probably didn't check the timing wheels so I can see that's a possibility - but the pistons and cams are identical (compared between mine and a non-cat Phase 2).

Help! I thought I'd got there, but now not so sure....

Adrian
 
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