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Corsa Z16 engine builds
Z16 / A16 / B 16 Engine failure recovery – P4 problem
Why does the 1600CC engine like to kill piston 4?
Through data logging many cars with this engine installed we have found there are reasons why the little engine has a poor chance of surviving.
Its actually a compound issue that contributes towards them not lasting, hardware related and mapping related too. If you data log the Z16/A16 series engine through a dyno pull , you often see that on the stock tune with 100% stock hardware , the injector duty cycle will already be over what you would aim for in a performance tune. Basically the injectors fitted run flat out under a nice long dyno pull through 5th gear , the same happens out on the road. This alone is a worrying factor , running the injectors so flat out in a performance tune we find that on the odd occasion the injectors will start to open erratic making them unable to provide the right amount of fuel at the right time.
Considering that under a constant pull the injectors already cap out the injector duty cycle, considering our opinion of the stock already too lean mid range fuelling, then consider that the Corsa VXR has the overboost feature mapped into the ECU . This allows some extra power for a short time for overtaking, probably a more powerful feel in general when you hit the throttle hard too.
Our opinion of the standard injectors is that they are too small , our opinion of the mid range fuelling is that it is too lean , our opinion of adding overboost function on top of that is just crazy ! When we do a high load dyno pull starting from low down in the RPM , we out run the overboost timer before we start the dyno pull , the injectors are already running too high at the peak power region . At peak torque we already think it runs too lean for the boost , adding over boost to either area makes for a certified disaster !
In a nutshell , if you were to prepare for an overtake on the motorway , you drop a gear to 5th gear , pull out and let the overboost feature deliver the extra power – the engine is solely staying together on the ECU's knock control. Its impossible for the ECU to demand the right amount of fuel as the hardware does not support doing so , it only ever leaves you with the kind of fuelling that makes you abandon a dyno run.
What can ou do about it ?
If the car has never been driven hard and you don't plan to do so then there is not so much need to worry. If you plan to use all of the HP for most of the time then you probably know already a lot about this subject.
Fitting 395CC injectors on a stock tune without hardware upgrades
Our opinion one solution to help towards a longer life without issue . These injectors are such a small size increase over the standard item that they help cure the issue. Removing the front Oxygen sensor from the car and running the engine lets you see the fuelling output without the ECU making any corrections – it cant see the fuelling so it cant correct it . Doing this on a Corsa VXR you will find that on idle , light load and light cruise , the whole fuelling output is on the lean side of stoich for petrol. Some areas run towards the lambda 1.1 area , making the engine stumble slightly and lightly misfire. With the front Oygen sensor fitted, the Ecu will see the mismatch from target and correct the fuelling so you don't notice this , to us as a tuner it makes us suspect that the ECU is set up wrong or needs a slightly larger injector to deliver the fuel for the current given settings.
Under full load the ECU goes into a more open loop fuelling strategy where its adding fuel for measured air , predetermined by the ECU map. We already think the ECU runs too lean in this area so a slightly larger injector again has no downside, especially more so when it seems like it runs right with them installed. There are some minor differences with the characteristics between the stock injector and the upgrade 395CC data wise. The dead time and non linier small pulse width chart do vary slightly , this small difference in these areas must be deemed acceptable by a lot of people, we are still yet to see any of the other softwares feature this data entered correctly. It is often just the single value injector scale that most tuners will change to allow the ECU to cope with the bigger injectors roughly. The stock injector and the 395CC version are a very close match to each other , the differences are very small , you are better off in having the engine run that little bit richer all the time.
The end result from fitting the 395CC will be that the car will idle closer to stoich , drive in part throttle closer to stoich and be a bit richer in the mid range and flat out. Refitting the front oxygen sensor so that the ECU can see the fuelling output will leave with a short term fuel trim similar to what you would see on the stock injectors , just to the richer and safe side of things all the time.
The 395CC injector are also able to deal with the over boost feature in a much less frightening manner , its almost as if they intended to fit this injector from the start …........
Map it with bigger injectors.
For the same reason as above , running loo lean and too much boost is frightening. When it comes to software changes we would recommend a bigger injector again. The smallest injector we would actually sell you for the Corsa VXR in a performance sensor would be the 613CC injector .
This injector is a good increase in size increase so software changes are necessary, changing the injectors and mapping to suit will often help increase the life of the engine . We run the engine with a bit more fuel when you are requesting power and this over the long term keeps them safer. Its not the be all and end all solution , you may find that if you car has already had a hard life and is already on its way out , this solution would not help the situation. This only works really if you know the engine has had a good life and is in good health.
Forge and forget
Making the engine stronger from the start is another approach , more costly but more reliable , even more so if combined with the above 395CC method. The end result will be likely to be down on HP a little through the engine having a bit less compression , down on power through being a little rich but certainly you should have no issue with the engines life . The forged engine build can be further optimised with larger injectors again as we would the 613CC versions – on a good condition stock turbo , full 3” exhaust , stage 2 type intercooler you will see peak power to be in the 245+HP region. Hybrid turbos on the forged engine with the same supporting modifications are now available to more or less le you hit the 300HP on a standard type turbo. More again with a bigger one
When the P4 issue comes around there really are 3 main scenarios that we help our customers solve
1- Customer notices something is not right very soon onto the issue happening,
in not all cases will the engine sound bad , the engine may not smoke , all you will notice is a bit less power and the engine seems to stumble lightly at times, the compression on cylinder 4 will have also dropped at this point. In this case its often that an area of the ring land material -
has cracked but not yet broke away enough to give any serious issue.
2- Customer notices smoke and lack of engine performance – turns engine off straight away
In this case the same issue has happened and the engine has run for a little longer ,or a little harder.
In respect to the P4 issue with regards to smoke , this is usually when the ring land material has broke away enough to contact the bore wall . This causes a build up of aluminium on the bore walls meaning the rings are un-able to seal up. The longer the engine is run for in this case the worse the damage will be. In most cases we can fix this by over boring the engine and forging to get back to being right.
3 Customers engine stops/ sounds terrible – will not start again – smoke – oil
In this case its likely that P4 has seen a total failure to the point that serious damage has been done – in some extreme cases it can be best to search for another bottom end . A lot of them can be overbored and saved but depending what you want from the car it may not be an option.
Fixing It
Catching the problem at the soonest point is the best case you can hope for. If there is no major debris or damage at this point we can dismantle the engine keeping this relatively clean , machine hone the bores over ever so slightly to give some new rings a surface to bed into – clean the block out thoroughly and re assemble the engine with some new bearing shells and a clearance report. This makes for the first step on the pricing ladder of fixing the problem , this is a solution that is perfect for those just wanting to fix the engine and maybe only seek a little more performance from the engine as a whole.
As part of this engine building service we will run the engine in fully and adjust the map to be safe should it be needed , the car will be returned to you ready to use as normal without worry. The exact output will vary for all as every case as they are all different. In instances where you already have a performance tune that is locked out we can make recommendations or also discus changing the software should you wish.
Wossner pistons
FCP H beam conrods
OE Spec gaskets
OE spec bolts
Fully run in
Map adjusted to be safe
Power / Torque reported
Further recommendations for tuning
Filled with Millers oil
£2600 INC Vat *
Fixing it and making it faster
More often than than not , fixing it and making it faster is what we are asked to do. After forging, the only components that stop your engine putting out even more power are the clutch and flywheel ( as well as air con delete if you wish for the most power – the AC pump is prone to failure at higher RPMS than the stock limiter )
The stock dual mass flywheel system and original clutch are fine for standard power – they are happy to sit and take nearly 100K miles before you will have to change this as a service item . The problem happens when you want to turn the power up . Firstly come a point the clutch will no longer hold the required torque , secondly if you need to raise the RPM limiter to get the performance out of your engine more than likely the dual mass flywheel will get a bit of a wobble on and potentially nock out the bottom end. You can tell if your car is doing this a bit when the clutch pedal starts to firm up higher in the RPM . Eventually this wobble gets too much for the bottom end shells and often they will either knock out the main bearing on that end , or sometimes the dual mass flywheel will give up before this happens.
As the 1600CC engine needs the RPM to make power , the solid lifter buckets in the Corsa VXR cylinder head have no issue with 8000RPM+ , its essential to balance the engine while its being assembled as best you can. Its impossible to do so with a worn dual mass flywheel , its very hard to do on a new dual mass flywheel even when you have the right equipment. The more normal thing to do in this instance is to go for a solid type flywheel and upgraded clutch. This can all be balanced as a rotating assembly , keeping the vibration in check will always lead to a longer engine life.
In all of our full performance engine builds we use a solid flywheel , if you already have one and the clutch is good too then we can still balance them all together. It does not have to be new but sometimes it can make things last longer and be more straight forward to complete. Our best advise is to use something from TTV – we use their billet flywheels in all our builds, we have put our trust into them for the last 10 years and never seen a failure.
Wossner pistons
FCP H Beam Conrods
OE Spec gaskets
OE spec bolts
Fully run in
supply and install 613 CC injectors
Map optimised for full potential of setup
TTV billet flywheel
TTV billet Clutch
ARP flywheel bolts
Balanced rotating assembly
Air con delete
Power / Torque reported
Further recommendations for tuning
Filled with Millers oil
£4400 Inc Vat *
This setup above with the right turbo setup will take 360-380HP
estimated power
Stock intercooler – any exhaust – Cone filter 200-210HP
Stock turbo + 2.5” Decat Exhaust + Big intercooler + Cone filter 225-230HP
Stock turbo +3” Decat Exhaust + Big intercooler + Cone filter 230-245HP
Stock turbo +3” Exhaust + Big intercooler + Cone filter+ Turbosmart actuator and recirc valve 245+HP (MAX Seen 256HP Stock turbo )
To add a 3” piper exhaust to this package or a decent intercooler get in touch .
If you already have a single mass flywheel remove 1200 from this price
Fixing it and making it really fast
Our reputation has been built on performance output , this is what we specialise in the most. We have some relatively crazy options for the 1600 CC engine should you want to make the most. We have been involved with tuning multiple 500HP Corsa's ,we are also involved with the parts too . If you like billet camshafts , crankshafts , flywheels and clutches then this is what we are about.
300-350 Hp 7700RPM Limit
This power bracket is a really good area for the 1600CC engine , they perform well on track and road with this kind of setup. Keeping the turbo on the smaller side of things will make them transition into boost at part throttle nicer often feeling less “lazy”. Using a hybrid turbo also keeps the setup much more simple to install, being built into more or less the factory fit turbo setup there are minimal modifications needing to be made to make things work. We have tested and used KRS turbos for years , they have been pushed past the safe limit and tested there to without fail. Our hybrid 350HP package is hard to beat if you are looking for all round performance without going to a tubular manifold.
Wossner pistons
FCP H Beam Con rods
OE Spec gaskets
OE spec bolts
Fully run in
supply and install 613 CC injectors
KRS Stage 2 KO4 turbo with turbosmart actuator
80MM Maffless inlet system and large filter
Catcams billet fast road cams + new buckets
Map optimised for full potential of setup
TTV billet flywheel
TTV billet Clutch
ARP flywheel bolts
Balanced rotating assembly
Air con delete
Power / Torque reported
Further recommendations for tuning
Filled with Millers oil
£6500 Inc Vat *
Full 3” turbo back exhaust must be used
Airtec Intercooler or better required
If you want to make the engine even more safe then the addition of ARP head studs is possible but not needed at 350 HP
Going big
This is probably the area we specialise in most , we have a lot of experience in the high power builds. We have tuned some of the highest power 1600CC road running standard ECU Corsa's and we are also currently cooking up another spicy Corsa build to move the goal posts a little bit further back again. We can cater with off the shelf developed and proven parts for 500HP + , we would also be fairly confident that we know the ingredients for a solid 600 HP too. When we get to this kind of power there are a lot of things we have to take into consideration , more than likely we will need to speak with you about anything like this so please get in touch !
*car is in something like the state suggested