The 205 was Peugeot's attempt
to really see off the other hot hatches such as the XR2/3 and Golf Gti. The
power output is very high compared to other engines of the time and was a
result of Peugeot paying a lot of attention to engine design detail. The legacy
of this high output is that it is not as simple to improve the power as with
other engines that are in a lower state of tune as standard. A great many
modified engines that both I and colleagues in the trade see, have LESS power
than standard and the companies selling engine conversions tend to boast the
most ridiculously inflated power claims compared to companies specializing in
other marques.
Let's compare the 1.9 Gti
engine with the Golf 8 valve and see how Peugeot got so much power. The 1.9 has
a claimed 130 PS (128 bhp) compared to the Golf's 112/115 PS (110/113 bhp) in
1.8 or 2.0 litre form. Firstly Peugeot made the bore larger at 83mm and this
allowed them to fit larger valves - 41.6mm compared to the Golf GTi's 40mm
items. This 8% increase in valve area is worth about 10 bhp. The head was given
large ports and a decent shape and flows very well for a standard item. The
induction system was carefully designed to flow well and flows enough to allow
even well modified engines to breathe ok. Peugeot got the exhaust system bang
on - it flows well, has good tuned lengths and an excellent manifold design -
whatever you do, don't waste money on an aftermarket system - you won't get
more power - you'll probably get a fair bit less. When it rusts away go and buy
a genuine Peugeot item - not a pattern part. Finally Peugeot topped the
engine off with a really good camshaft. Most 8 valve engines of this size have
about 400 thou valve lift as standard and a fast road cam from Piper or Kent
etc will add another perhaps 30 to 40 thou to that. The Pug 1.9 has 445 thou
lift as standard and fairly long duration as well. It's already more than a
match for an aftermarket fast road cam for most other engines. The good exhaust
and big cam add the other 5 or so bhp that similar engines lack.
So in effect the Peugeot
engine is already the equivalent of a fast road tuned Golf. Given that the
exhaust and induction system are so good what can we do to improve the power
further? Well the main area left to improve is the cylinder head but it takes
really well developed port shapes to give more flow and that takes flow bench
time. There is also some power available from even higher lift/longer duration
cams but at the expense of some tractability. We'll look at both areas later.
Both the 1.6 and 1.9 share
the same 83mm bore and the capacity comes from different crank strokes - 73mm
and 88mm respectively. The wet liner engine is strong and reliable with a few
idiosyncrasies to watch out for. The liners have no shims underneath and must
protrude above the top of the block by the right amount to seal properly. This
relies on accurate machining at the factory as the clearance is not adjustable.
4 to 5 thou is the figure to look for - too much lower than this and leaking
head gaskets and/or water in the sump can result. Over time the liners tend to
distort to a slightly oval shape because of the constant piston thrust in one
direction. However, if you remove the liners and leave them on a shelf for a
while they seem to go back round again - weird but true. A good tip when
rebuilding an engine that is still in good enough condition to not warrant new
liners is to refit them turned 180 degrees round in the block. Most of the wear
takes place on the thrust side of the engine and rotating the liners lets the
relatively unworn side seal against the rings better.
Beware when removing and
refitting the cylinder head not to turn the crank until the head bolts are done
back up or the pistons will move the liners. The liners just sit on machined
recesses at the base of the block and are sealed with thin rubber O rings. Move
them and they are unlikely to seal again without new O rings and the consequence
will be water leaking from the block into the sump oil.
Peugeot did a huge amount of
messing about over the years with the number and arrangement of plain and
grooved main bearing shells, the reasons for which have always eluded me. The
Haynes manual comments on the complexity of it all and states that when they
stripped their own test engine it didn't even have one of the bearing
combinations listed in the official Peugeot charts. Other engines nearly always
have 5 grooved bearings in the block and 5 plain in the caps for very good
reasons of oil supply to the crank. That's the way I build the Peugeots too,
regardless of year, and they run perfectly happily like this of course. Peugeot
actually finally settled on this combination anyway for later 8 valve engines
and the 16 valve engine.
The rods are very sturdy and
survive race use happily enough so road use is no problem for them even on
tuned engines. Standard pistons rarely cause problems either except for
sustained use over 7,500 rpm.
Early engines had an oil pump
drive which relied only on the friction of the tightened crank pulley nut to
turn it - no woodruff key or other locking system. This strikes me as one of
the worst bits of engine design I have ever seen and the first time I rebuilt one
of these engines I was convinced for ages that I'd lost a part somewhere. I
know someone whose Mi16 engine grenaded because of not tightening that bolt up
properly and after a few miles with no oil pressure everything came to a very
expensive halt. You have been warned.
Early 1.6s had smaller valves
than late models but then went to the 41.6mm inlet and 34.5mm exhaust of the
1.9 engine. From then on there is no difference between the cylinder heads of
late 1.6 and 1.9 engines and in fact they aren't even stamped with the engine
size. The exhaust valve is perhaps a bit small but little extra power comes
from fitting larger ones and the expense is not warranted except perhaps for
big budget race engines. The inlet valve can be usefully increased in size
though and 43.5mm will just clear the bores although 43mm is the normal big
valve option I offer for road engines. As I said above, more 205s get badly
modified by so called "expert" engine tuners than any other make of
car. The cylinder head doesn't escape their attentions. I've seen a £400
"fully ported" head from one of the less reputable Peugeot
"specialists" where the badly worn guides hadn't been replaced, the
seats hadn't been recut, the valves hadn't been refaced and the porting consisted
of a bit of polishing with a flapwheel in the areas that could be reached with
the guides still in the head. Not surprisingly it didn't make any more power
although 160 bhp was the claim. It must have taken nearly an hour to do that
head ! A properly ported one takes several days of carefully detailed work.
Cam bearing wear can be a
problem on high mileage engines especially if there has been any bottom end
damage. Bits of crank bearing material tend to circulate with the oil and chew
up the cam bearings and as these are machined directly into the head there is
not much you can do to rectify it. Guides wear out pretty fast too - especially
on the exhaust side and any decent head mods should include new guides if they
are outside the wear limits.
There is not as much scope
for improving flow compared with many other heads because Peugeot did such a
good job as standard in the quest for that 128 bhp. Port shape is critical to
getting better flow and it is the seats, valve throat and short side bend that
need the most work. The main part of the port is plenty big enough as standard
and needs no enlarging but as it is the easy part to reach, inept tuners take
huge amounts of metal out here to make it look as though something constructive
has been done. This drops the port airspeed and hurts low rpm power without
increasing total airflow at all. 3 angle seats are a must and reshaping the
valves in the seat area helps too. The guides have to come out to do the work
properly and one sign of a badly modified head is lumps missing from the guides
where they've been hit by the porting cutters.
With the optimum port and
valve seat shapes it is possible to squeeze about 8% to 10% extra flow and
power potential out of the standard valve sizes. So about 10 to 12 bhp on a std
engine and proportionally more in conjunction with other tuning mods. Polishing
and enlarging the straight part of the port without removing the guides or
cutting the seats properly won't achieve anything at all except to make the
head look superficially pretty. Sadly most heads fall into this category.
Given how well the std head
flows it is big valve heads that make the most sense and achieve the best value
for money per bhp gained. With larger seat inserts, 43mm inlet valves and the
port shapes properly worked to get the most out of the bigger valves it is
possible to get an extra 15% bhp. That's about 18 bhp on a std engine and 20 or
more on a tuned one. On a race engine a properly ported BV head can easily be
worth 30 bhp.
A light skim to increase the
compression ratio can add a little more driveability but 10:1 is about as much
as you need for road use with standard or mild road cams on pump fuel. Longer
duration cams can stand more CR as with any other engine. 11:1 works well with
cams around 290 degrees duration such as the PT27 (ignore the 304 degrees
duration quoted in the Kent catalogue as they don't measure anything like
long).
The standard induction is a
plenum manifold with a single butterfly and Bosch LE fuel injection. The
manifold has big runners and flows plenty of air to work nicely with even well
modified big valve heads. The LE injection system measures the air flow by
means of an air flap which opens progressively as more air flows into the
engine. The ECU then hopefully injects the right amount of fuel based on what
the air flap meter is telling it. This works fine except at low rpm with long
duration cams. The reason is that the air flap likes the airflow to be steady
and in one direction all the time. Big cams cause the airflow to pulse strongly
at low rpm and this makes the flap vibrate which confuses the ECU and leads to
erratic idling. At higher rpm once the engine has "come on the cam"
everything smoothes out and works fine again. Even with the standard cam the
engine isn't renowned for having the best idle characteristics in the world and
if you want to retain a good idle then stick to short duration cams (under 275
degrees). If you aren't bothered too much about idle quality then hotter cams
will work fine once the revs are up over 2000 or so. Fitting a mappable ECU
controlled by a throttle position sensor and doing away with the air flap meter
eliminates the idle problem but is costly. You might as well pay the extra and
go straight to throttle bodies as mess with the standard induction system to
that extent.
Fitting DCOE carbs is another
way of eliminating the air flap problem and is worth a few more bhp. Maybe 5 to
10 depending on how highly tuned the engine is. They are also easier to
calibrate than a fuel injection system but won't get anywhere near the same
economy or tractability. Note that the Mangoletsi DCOE inlet manifold, which is
the most commonly available one, needs an awful lot of work to match its ports
up with those of the cylinder head. As cast it only has tiny holes through the
runners which are very restrictive. It takes a good couple of hours with a
grinder to remove the required aluminium and port the manifold properly so be
prepared for the cost of this if you want the engine to produce the power it
should be capable of.
The ultimate induction system
is throttle bodies with mappable injection and ignition. This will add 15 or
more bhp just from the extra airflow and also allow you to use longer duration
cams without losing tractability. The total additional power potential is
therefore pretty high. Cost is around £1400 plus fitting and setting up.
This can be a nice short
section. The standard Peugeot systems are excellent and on a standard or road
tuned engine you'll be wasting your money fitting anything else. Only on rally
or race engines with long duration cams might it pay to fit a tubular 4-2-1
type manifold and larger bore system but that's outside the scope of this road
oriented tuning guide. Also beware of non Peugeot standard replacement systems.
You might save a few pounds but also lose a goodly chunk of bhp into the
bargain.
Because the standard cam is a
fairly rorty item anyway it pays not to go too mad in this area, especially if
the standard air flap induction system is being retained and idle quality is
important to you. A Kent or Piper 270 degree fast road cam is worth 5 bhp or so
(nothing like the 15 bhp you sometimes see claimed) but take note that the
bigger cam lobes might not clear the inside of the cylinder head and some
grinding may be needed to get clearance. Idle quality will suffer somewhat but
still be adequate for most people. More cam can be used while still retaining
driveability if carbs or throttle bodies and a mappable ignition system are
fitted.
There's no reason not to use
hotter cams than this with the standard induction system providing you are
aware of the downsides, which will include trouble with emissions at MOT time.
Temporarily refitting the standard cam is an option if you really want the
extra power that long duration cams allow. For example, a Kent PT22 is worth
about 10 bhp over the standard cam and a Kent PT27 about 15 bhp more than the
standard cam.
Finally, note that Peugeot
changed the bolt that holds the cam pulley on from a 12mm diameter bolt on
early engines to a 10mm bolt on later ones. As with the crank bearings, why on
earth they messed around with something which was fine to start with I have no
idea. Maybe the smaller bolt saved 0.1 of a penny per engine and they were
going through hard times. All Kent and Piper cams use blanks with the original
12mm thread in them so if you have an engine with a 10mm bolt you'll need to go
and buy the 12mm one from a Peugeot dealer to be able to fit the new cam.
STANDARD ENGINES
I don't normally have to go
into so much detail about the claimed standard power output in these tuning
guides but the 205 Gti is a bit of a minefield in this area and it has knock on
effects on how some of the less honest engine tuning companies arrive at their
own power claims. To restate the rules I use for equating flywheel and wheel
bhp on front wheel drive cars. The simple equation is to deduct 15% from the
flywheel bhp and the longer version is deduct 10% plus a further 10 bhp. The
chart below shows the wheel bhp figures we would expect to see using those two
equations on the claimed standard flywheel power.
|
ENGINE |
CLAIMED
FLYWHEEL BHP |
ESTIMATED WHEEL BHP |
ESTIMATED WHEEL BHP |
|
1.6
GTI |
113
BHP (115 PS) |
92
BHP |
96
BHP |
|
1.9
GTI |
128
BHP (130 PS) |
105
BHP |
109
BHP |
So do we see those power
levels from standard cars on the rollers? In the case of the 1.6 most
certainly. A few cars even make a tad more power. 98 bhp is about the highest I
recall seeing. Only a really bad one will show less than 90. As for the 1.9 a
few of them show that sort of power but it's a lot less common. About 108 bhp
is the most I tend to see. So we could say that on average the engines are
split by closer to 10 bhp than the 15 that the factory claim. A good 1.6 will
have its claimed 113 at the flywheel but only an exceptional 1.9 will show 128.
An average 1.9 will show anywhere between high 90s and just over 100 bhp at the
wheels (so about 120 to 125 bhp flywheel) and really poor engines as little as
90 or 95. Highly tuned engines tend to go out of tune easily and show the
effects of mileage and wear and tear more than run of the mill engines. Factor
in 100,000 miles of wear, injectors starting to clog up, non standard exhaust
and air filters and it isn't difficult to shed 15 or more bhp from an engine
that probably never really had 128 when it was new.
THE 160 BHP SCAM
Most of the tuning companies
specializing in other marques, Ford, VW etc at least give decent value for
money. Unfortunately, in the murky waters of the Peugeot tuning world there are
a couple of real sharks lurking. One company in particular accounts for 90% of
the horror stories I get told by colleagues and customers. I'd say that at
least 50% of the people who phone or email me have either had a bad experience
themselves or know someone else who has suffered at the hands of this outfit.
Naming them here in print isn't possible of course but a trawl through the
postings in the various online Peugeot forums might reveal one or two names
cropping up more often than others. The most commonly promised power claim for
a road tuned 1.9 is 160 bhp. It seems to have become a standard target. A
ported standard valve head and a fast road cam of some description (usually
some mythical French made cam for which any further details are too secret to
give out) are supposedly all that is required to get this increase.
Take the power output of a
decent standard 1.9 as being around 125 bhp and you're looking at another 35
bhp to get up to 160. If a properly modified standard valve head is worth about
10 bhp and a tractable cam another 5 then something doesn't quite add up here -
even assuming that the work was done to a high standard which it probably isn't
going to be. Even with a rally cam the figures don't make sense. Of course it
may be that other people are magically able to extract much more flow from
their cylinder heads than me but if so I don't seem to see their work on the
race track. I've had the dubious pleasure of stripping one such supposed 160
bhp engine which the owner found no faster than when he took it in for the work
to be done and later showed 108 bhp at the wheels on an independent set of
rollers - about the same as a good standard one. The head work is described earlier
in this article so no surprise that it represented no power gain. The
celebrated and rather secret "French" cam was perhaps even more
interesting. It bore all the same casting marks as a standard cam which was
intriguing. Putting a dial gauge on the lobes revealed the standard 445 thou
lift. Measuring the entire lobe profile and drawing it out on a graph failed to
spot any further differences. So almost certainly it really was made in France
- and had been living quite happily in that engine ever since Peugeot fitted it
on the production line. £300 for the pleasure of keeping the cam you drove in
with is hardly what I call value for money. The best bit was the subsequent two
page letter trying to justify how a "good" standard engine only made
90 at the wheels and so 108 bhp represented a huge gain due to their expert
workmanship and equated to the promised 160 flywheel. I think anyone who has to
rely on 52 bhp of non existent transmission losses to justify their work should
be in a different line of business.
The customer had however
failed to get a single thing established in advance or in writing. Such as the
exact make and part number of the cam he was paying for, whether the valve
seats would be recut, the guides replaced or any other detail. A Piper, Kent or
any other reputable cam will have a number stamped on the end and a
specification in the catalogue which can be checked against if required. If a
company is reluctant to tell you the lift, duration and timing figures of the
cam they are trying to sell you then ask yourself why. If you don't ask for at
least that minimum level of detail then Caveat Emptor I'm afraid. So what power
outputs are realistically possible with best quality work?
TUNED ENGINES
I hardly ever see 1.6 engines
these days but you can work on the basis they will show similar gains to a 1.9
but always remain about 10 to 15 bhp behind due to the smaller engine size.
I've pretty much said everything about power gains in the individual sections
above but to summarize them one last time. A good condition 1.9 with properly
ported standard valve head and 270 degree cam will show about 15 bhp more than
standard - say 140 bhp flywheel or a tad more (about 116 at the wheels). With a
big valve head you're up to 150 bhp (125 at the wheels). Add a pair of Weber
DCOEs and a genuine 160 bhp is possible. One I did to that exact spec some
years ago with a Piper 270 cam showed 134 bhp at the wheels on a reputable set
of rollers.
A big valve head on the
standard inlet manifold will also show about 160 bhp with a rally type cam such
as a PT27 and a skim to 11:1 CR but won't be fun to drive below 2,500 rpm and
probably won't pass an MOT unless you add a mappable ECU. No problem of course
if your car really is a rally car like the one I did to this spec in Feb 2002
which made 133 bhp at the wheels on what turned out to be a rather ropey bottom
end in need of a rebuild. I suspect there was a bit more to come with a decent
engine underneath that head. The bigger cam is adding back the 10 or so bhp you
are losing by not having the DCOEs. Add the DCOEs to that spec though and 170
bhp is there for the taking even if still a tad peaky for road use.
With throttle bodies, BV head
and rally type cam you're looking at a fairly tractable 180 bhp and that's
about the limit for road tuned engines. The TBs and mappable ECU will add a lot
of low rpm power and driveability compared with carbs or the standard induction
system.
If anyone promises you more
power for less work than the above then start reaching for the salt.
Ported standard valve head
with new guides, chemical clean, skim, 3 angle seats is £425. Fitting of the
valves is included if stem seals are being supplied by us as part of a gasket
set. Otherwise add £10 for supply of the seals. Machining of the inlet manifold
is recommended as below.
43mm valve head on big inlet
inserts, new guides is £650. Other comments as per the std valve head. To get
the best out of this head the inlet manifold needs opening up so as not to
restrict the head flow (£40) or use with throttle bodies and a properly matched
DCOE style manifold.
Shimming of the valve train
to suit the cam used - £40
Non standard cams with larger
cam lobes can foul the inside of the lifter bore area. This needs to be
machined before the valves are fitted and costs £30 if done during other head
work.