MC
22-10-03, 12:09 PM
Tuning the 1600 8v
When people ask me how to tune the 1.6 lump, I have a definitive answer. Unfortunately most people either don?t have the money to do that, or aren?t as dedicated to gaining power as I. For this reason, I thought I?d give a few examples on how to tune these engines when on different budgets. I haven?t gone into great detail as this isn?t a detailed ?How to?, but I?ve told you what changes are required for power.
Before I start, I?ll give one pearl of wisdom. If you plan to modify to any particular degree, don?t do it bit by bit. Save the money and do it all at the same time. This saves money in rebuilds, gaskets, bolts, fluids and setting up.
This first level of tuning, and possibly the most fun for money is simple. Just like every ?Lax Power? mag says, fit a performance filter and zorst. No rocket science here, except unlike on your average Saxo or Fiesta, it works. The 1600i Vauxhall lump responds very well to simple mods.
Start by adding the filter of your choice, the Piper cone filter works as well as any. You might want to just use a panel filter and supply it with cold air, but either way, you?ll notice the benefit.
Whilst the filter assembly and air flow meter (AFM) are removed, there is more to be done. The AFM can be modified by reducing the spring tension on the flap. This a) allows the flap to open further, allowing more air through, and telling the engine to add fuel too, and b) allows the flap to move more quickly, reducing resistance to air flow and increasing response to fuel needs. I suggest that you read the book ?How to Tune and Modify Bosch Fuel Injection? or ask someone that knows what they are doing. Don?t get greedy or you?ll make things worse. You can try to locate a larger AFM from another model. As long as the flow to signal ratio doesn?t change, it will work and reduce restriction. I haven?t tried this, but if someone does, let me know.
By removing the trunking that leads to the throttle body (TB), you will be able to see the butterfly. Open the throttle, and you?ll see that the butterfly has a large wedge on it. Remove this to allow MUCH more air into the engine. You can go further on the butterfly, but at this stage of tune, it?s not worth it. When working on the TB, make sure you do it removed from the engine. Last thing you want to do is to drop any objects into the engine.
Whilst working on the TB, check that the butterfly opens fully to 90 degrees. Most won?t, and this is a simple fault. The throttle mechanism relies on a small nylon bush to move through a slot in the gear. As this wears, it fails to open the throttle fully. Get a new one. It may sound vague, but have a look and you will see what I mean.
The zorst on the 1600i Nova isn?t too bad, but a decent performance one will finish off the transformation and unleash all the potential of the other mods. In itself it will gain quite a few pony power. My recommendation is a mild steel competition system and four branch. Don?t bother matching the exhaust to the head, as a slight lip on the exhaust side acts as an anti-reversion measure. It stops exhaust gases moving back through the head.
Your ignition system needs to be in good order. Get new plugs (not Bosch 4?s in my opinion) and leads. Nothing flash. I recommend champion leads, they seem to be put together better than any others I?ve played with. NGK plugs do the job well and don?t cost a fortune. So your ignition now works, but is it set-up correctly? Even though you haven?t done loads to your car, get it on a rolling road. There will be more power available, and you can check that all is working as it should.
Now at this point, you won?t have had to disturb your engine yet. From this point you can decide how much further you wish to go. The wise thing to do if you go any further is to get everything else done together.
It is difficult to know which to cover first, the head or the cam, which comes first? I?ll cover the camshaft as most people attack this first. Simple really, get a cam, fit it. Not really, my recommendation would be to go for a Piper 285 or a Kent AST2. Anything less and you?ll soon get bored of it and want more. Before you ask, no, it won?t make it too lumpy or difficult to drive. Fit new followers, either ones from the makers of the cam or genuine Vauxhall ones. Don?t but cheap ones, they are poor quality. Worn cam followers can loose as much lift as you?ve gained from your cam!
Cylinder heads. The more you can do the better. To put the price of a Bill Blydenstein (BB) head into perspective, I?ll give you a glimpse of machining costs. Buying and fitting larger valves to a head will cost around ?300-?350. Now add on the price of porting and wasting the valve stems. A (BB) B+ head will set you back around ?460, and you can?t argue with the performance gains. It?s worth it, no question.
If you?ve already decided you want to go further, and you have the money to do so, but you?re not a millionaire and like to drive round with subtle performance, the next step is for you. Your first purchase of the air filter is still needed, so having spent that money wasn?t a waste. In fact everything you did is still useful except the AFM modification. You are going to ditch the airflow meter, fit the filter direct to the TB and go for full mapping.
The AFM isn?t the worst that Vauxhall ever used, but it is still very restrictive. First thing to do is to ditch all of the trunking, AFM, ECU and remove the loom. You?ll be using a new ECU, such as DTA (?300-350) and you?ll need to add some new parts. You?ll need a lambda sensor, so if you?re manifold doesn?t already cater for this, you?ll need one fitting. The standard throttle position sensor isn?t good enough, so that needs replacing, and you won?t be using your dizzy anymore. A dis-pac will do the honours. There is a lot more too it, and I?m being very vague. I can?t talk you through this one, you need someone to show you how to do it. The benefits of the extra flow and full mapping will be instantly noticeable. You can sit like a pro with a laptop playing till your hearts content. You will have a data log and instant read out to help you fine tune the running, and you can raise the stupidly low RPM limit. One more thing to think about is that the 1600i has a similar size throttle body to the one that touring cars are limited too, and they make around 300bhp.
If you plan to modify your bottom end, its something that you should consider doing when playing with the head and cam, and possibly with the inlet (you need to remove the head to do a good job when fitting different induction systems). I wouldn?t recommend lightening and balancing. It?s not cheap, and unless you are in real competition and have screwed every last ounce of power from all else, it won?t be really beneficial. Start by getting things straight. Have a re-bore with 1mm larger pistons. Whilst at it, have your crank re-ground with oversized bearings. It?ll set you back a few hundred pounds, will make the block as good as new, will increase capacity, compression and therefore power.
Next step is to have the con-rods de-seemed and shot peended for extra strength. Fit ARP bolts and have the block decked/skimmed. Aim for around 12:1 compression.
Fitting Webber Twin 40 DCOE?s is the classic route for the 1600. It?s probably the most cost-effective way of gaining big power from the engine. To get them to work properly, use the ignition system from a carbed model, make sure you match the inlet manifold to the head, and get them set-up correctly. Use a recommended Weber expert. You?ll need to regulate the fuel, and there are a number of other issues to straighten out, but that can be answered elsewhere. You can run the carbs with the DTA management, but using the ignition side only.
Top of the list are multiple throttle bodies, they?ll need the engine management and the gubbins mentioned earlier. They?ll cost a few hundred from Jenvey, and they?ll extract the most from your engine.
You?ll notice that this list has become progressively vague. That is because most of the more serious mods, you?ll either understand, or pay someone to do. It?s not something you can pick up from a simple guide. You can go for turbocharging, but to be honest, to do it right you have to spend money. All turbocharged 1600 Vauxhalls run well short of the quickest NA cars with exception of one, and that one has been converted properly at great expense, and after learning the hard way that you can?t successfully TC on the cheap.
I've locked this post as even though others might have points to add or not agree, this is intended to pass on some ideas.
MC
When people ask me how to tune the 1.6 lump, I have a definitive answer. Unfortunately most people either don?t have the money to do that, or aren?t as dedicated to gaining power as I. For this reason, I thought I?d give a few examples on how to tune these engines when on different budgets. I haven?t gone into great detail as this isn?t a detailed ?How to?, but I?ve told you what changes are required for power.
Before I start, I?ll give one pearl of wisdom. If you plan to modify to any particular degree, don?t do it bit by bit. Save the money and do it all at the same time. This saves money in rebuilds, gaskets, bolts, fluids and setting up.
This first level of tuning, and possibly the most fun for money is simple. Just like every ?Lax Power? mag says, fit a performance filter and zorst. No rocket science here, except unlike on your average Saxo or Fiesta, it works. The 1600i Vauxhall lump responds very well to simple mods.
Start by adding the filter of your choice, the Piper cone filter works as well as any. You might want to just use a panel filter and supply it with cold air, but either way, you?ll notice the benefit.
Whilst the filter assembly and air flow meter (AFM) are removed, there is more to be done. The AFM can be modified by reducing the spring tension on the flap. This a) allows the flap to open further, allowing more air through, and telling the engine to add fuel too, and b) allows the flap to move more quickly, reducing resistance to air flow and increasing response to fuel needs. I suggest that you read the book ?How to Tune and Modify Bosch Fuel Injection? or ask someone that knows what they are doing. Don?t get greedy or you?ll make things worse. You can try to locate a larger AFM from another model. As long as the flow to signal ratio doesn?t change, it will work and reduce restriction. I haven?t tried this, but if someone does, let me know.
By removing the trunking that leads to the throttle body (TB), you will be able to see the butterfly. Open the throttle, and you?ll see that the butterfly has a large wedge on it. Remove this to allow MUCH more air into the engine. You can go further on the butterfly, but at this stage of tune, it?s not worth it. When working on the TB, make sure you do it removed from the engine. Last thing you want to do is to drop any objects into the engine.
Whilst working on the TB, check that the butterfly opens fully to 90 degrees. Most won?t, and this is a simple fault. The throttle mechanism relies on a small nylon bush to move through a slot in the gear. As this wears, it fails to open the throttle fully. Get a new one. It may sound vague, but have a look and you will see what I mean.
The zorst on the 1600i Nova isn?t too bad, but a decent performance one will finish off the transformation and unleash all the potential of the other mods. In itself it will gain quite a few pony power. My recommendation is a mild steel competition system and four branch. Don?t bother matching the exhaust to the head, as a slight lip on the exhaust side acts as an anti-reversion measure. It stops exhaust gases moving back through the head.
Your ignition system needs to be in good order. Get new plugs (not Bosch 4?s in my opinion) and leads. Nothing flash. I recommend champion leads, they seem to be put together better than any others I?ve played with. NGK plugs do the job well and don?t cost a fortune. So your ignition now works, but is it set-up correctly? Even though you haven?t done loads to your car, get it on a rolling road. There will be more power available, and you can check that all is working as it should.
Now at this point, you won?t have had to disturb your engine yet. From this point you can decide how much further you wish to go. The wise thing to do if you go any further is to get everything else done together.
It is difficult to know which to cover first, the head or the cam, which comes first? I?ll cover the camshaft as most people attack this first. Simple really, get a cam, fit it. Not really, my recommendation would be to go for a Piper 285 or a Kent AST2. Anything less and you?ll soon get bored of it and want more. Before you ask, no, it won?t make it too lumpy or difficult to drive. Fit new followers, either ones from the makers of the cam or genuine Vauxhall ones. Don?t but cheap ones, they are poor quality. Worn cam followers can loose as much lift as you?ve gained from your cam!
Cylinder heads. The more you can do the better. To put the price of a Bill Blydenstein (BB) head into perspective, I?ll give you a glimpse of machining costs. Buying and fitting larger valves to a head will cost around ?300-?350. Now add on the price of porting and wasting the valve stems. A (BB) B+ head will set you back around ?460, and you can?t argue with the performance gains. It?s worth it, no question.
If you?ve already decided you want to go further, and you have the money to do so, but you?re not a millionaire and like to drive round with subtle performance, the next step is for you. Your first purchase of the air filter is still needed, so having spent that money wasn?t a waste. In fact everything you did is still useful except the AFM modification. You are going to ditch the airflow meter, fit the filter direct to the TB and go for full mapping.
The AFM isn?t the worst that Vauxhall ever used, but it is still very restrictive. First thing to do is to ditch all of the trunking, AFM, ECU and remove the loom. You?ll be using a new ECU, such as DTA (?300-350) and you?ll need to add some new parts. You?ll need a lambda sensor, so if you?re manifold doesn?t already cater for this, you?ll need one fitting. The standard throttle position sensor isn?t good enough, so that needs replacing, and you won?t be using your dizzy anymore. A dis-pac will do the honours. There is a lot more too it, and I?m being very vague. I can?t talk you through this one, you need someone to show you how to do it. The benefits of the extra flow and full mapping will be instantly noticeable. You can sit like a pro with a laptop playing till your hearts content. You will have a data log and instant read out to help you fine tune the running, and you can raise the stupidly low RPM limit. One more thing to think about is that the 1600i has a similar size throttle body to the one that touring cars are limited too, and they make around 300bhp.
If you plan to modify your bottom end, its something that you should consider doing when playing with the head and cam, and possibly with the inlet (you need to remove the head to do a good job when fitting different induction systems). I wouldn?t recommend lightening and balancing. It?s not cheap, and unless you are in real competition and have screwed every last ounce of power from all else, it won?t be really beneficial. Start by getting things straight. Have a re-bore with 1mm larger pistons. Whilst at it, have your crank re-ground with oversized bearings. It?ll set you back a few hundred pounds, will make the block as good as new, will increase capacity, compression and therefore power.
Next step is to have the con-rods de-seemed and shot peended for extra strength. Fit ARP bolts and have the block decked/skimmed. Aim for around 12:1 compression.
Fitting Webber Twin 40 DCOE?s is the classic route for the 1600. It?s probably the most cost-effective way of gaining big power from the engine. To get them to work properly, use the ignition system from a carbed model, make sure you match the inlet manifold to the head, and get them set-up correctly. Use a recommended Weber expert. You?ll need to regulate the fuel, and there are a number of other issues to straighten out, but that can be answered elsewhere. You can run the carbs with the DTA management, but using the ignition side only.
Top of the list are multiple throttle bodies, they?ll need the engine management and the gubbins mentioned earlier. They?ll cost a few hundred from Jenvey, and they?ll extract the most from your engine.
You?ll notice that this list has become progressively vague. That is because most of the more serious mods, you?ll either understand, or pay someone to do. It?s not something you can pick up from a simple guide. You can go for turbocharging, but to be honest, to do it right you have to spend money. All turbocharged 1600 Vauxhalls run well short of the quickest NA cars with exception of one, and that one has been converted properly at great expense, and after learning the hard way that you can?t successfully TC on the cheap.
I've locked this post as even though others might have points to add or not agree, this is intended to pass on some ideas.
MC