mike85gn
02-11-2004, 03:56 PM
After carefully examining the technical information gathered over the past several years in respect to the "hotair" turbo Buicks ('84/'85), it has been realized by many members what is really required to make a non-intercooled car move. The following recipe is not really a specific recipe, but more of a guide to getting best performance possible out of these cars, and is based on the experiences of not only myself, but many other hotair enthusiasts. This recipe assumes a stock, properly running car is used. If the car itself is not in good overall mechanical condition, then don’t start modifying the car, as you’ll probably just expedite some form of failure. Please note, while this document is targeted mostly at the hotair cars, the basics for both the '84/'85 and '86/'87 cars are very much the same, and good portions of this document apply to both configurations.
Always follow basic "spring cleaning" guidelines. Change oil frequently with high-quality synthetic oil. Make sure your spark plug wires are in good condition, and make sure you are using the proper spark plugs for your power level. Most stock hotair cars are best off with stock Delco plugs. Make sure vaccum lines and hose clamps are in good repair. Be sure to change the PCV valve. Set the throttle valve cable, and set the throttle position sensor. Ensure your transmission and differential have plenty of their respective fluids to increase longevity. Neither of these require frequent changes, so you might as well make sure it's done right away, instead of letting any possible problems compound themselves over time. These steps are vital to the proper running of your GN or T-type, especially considering they are almost 20 years old now. The extra attention paid now will pay off in the long run.
We’re going to start by increasing the fueling to the engine. This will ensure we are not running lean, and will add the important factor of tunability to the car. Based on popular opinion and real-world results, the following items can be considered as a necessity when modifying your Buick:
* Walbro 307/340 fuel pump
* Hotwire kit
* Adjustable fuel pressure regulator
This gives us a good basis for future upgrades in regards to adding more boost and fuel. These components are available from several vendors at very reasonable prices, and are able to support a good deal of power. At this level, one should also consider:
* Boost Gauge
* Scan Tool
This will allow us not only to monitor the engines specifics, but will also allow us to record and play back several frames of data. Your scantool is your best friend! For this purpose, either the TurboLink or OTC tools are a real value. Using the information given by the scan tool, we can begin tuning the car for maximum performance and reliability. First, set the IAC. Then, start tuning the idle characteristics, such as BLM and INT (they should be between 118-138), and then you should be ready to start tuning the WOT performance. It is wise to always watch the knock retard and make sure that proper O2 values are being read. Typically, the Hotair cars prefer a little more fuel than the intercooled cars do. I normally tune for just over 800mV at WOT on my Turbolink with pump gas. This gives a bit of a safety net, and still provides a power increase. Try to get it as close to that mark with little to no knock retard (none is ideal). If it is proving difficult, then consider keeping your foot out of it until you complete the next step.
* Adjustable wastegate rod
This gives us the ability to fine tune boost levels as well, giving us much more tuning flexibility. This should allow us to tune for minimum KR and ideal O2 voltages, while providing a good increase in power. If your idle characteristics are optimized properly, then you should be able to use the adjustable wastegate rod and the adjustable fuel pressure regulator to fine tune WOT performance and the car will run great both on the street and at the track.
Standard hot-rodder philosophy would lead us to believe basic induction and exhaust work should come next. Here is where peoples opinions may start to differ. IMO, there are a few good options, but here is what I would suggest based on experience:
* Gutted or no catalytic converter
* Free flowing or no mufflers
* K&N cone or complete induction kit
* Larger downpipe
This is where you can really start feeling a difference in power output. The lower exhaust restriction on the turbo will allow it to spool up much faster, and you should notice a slight decrease in boost level. Grab the scantool and retune, keep checking the idle and WOT settings until you achieve optimum performance with as little knock retard as possible. Always keep in mind, though, the possibility that you may have an exhaust leak somewhere before the turbocharger. It is important to eliminate these before continuing, as they contribute greatly to poor turbocharger performance. You will build pressure more slowly, and your maximum boost level may be severely handicapped. You may need to consider getting your headers welded if they are cracked, or buying new ones altogether. The uppipe and crossover pipe are likewise prone to leaking, and stainless steel replacements are available for a reasonable cost.
Begin to consider upgraded tires or drag slicks at this point, as traction may become a problem. Traction bars are optional, several people are of mixed opinion of them. I believe the stock suspension is a very good foundation to work with, but, like many other things, it's getting old. Replace the bushings with a bushing kit, and be sure to pick up the GNX bushings as well. A longer pinion snubber may or may not help, I have noticed that my pinion is bumping the snubber on high boost launches so I do see a use for it. Airbags are also a good investment, with a few PSI in them, they can help your car float down the road. For racing, filling the passenger side airbag to 12-15 PSI can help keep the rear end planted firmly. Some people box the lower control arms, this requires some welding, but is fairly simple to do. Kits are available from a variety of locations.
Of course, after the long life of our engines, there are some disposable parts which should be replaced as they may be a weak link in making power, such as:
* Valve springs
* Timing chain
The last thing you want is to be flying down the track at wide open throttle and have your timing chain snap. Invest in quality replacement. The valve springs are a notoriously weak link in our valvetrain, so it is wise to make sure yours are fresh or you may experience poor top end performance. A basic top end freshening is a little more insurance in terms of engine strength, and anything to keep your car from becoming a garage queen is welcome!
With all of the proper basic equipment in place, a few other little goodies to enhance performance:
* Performance PROM chip
* Low temperature (160º) thermostat
* Throttle body coolant bypass
The chip will recalibrate fuel, boost, and ignition timing for improved performance. Be sure to do additional tuning after adding this, the different timing, fueling, and boost characteristics could require more fuel pressure or lower boost levels to successfully fight off detonation. The thermostat is rated to open at a lower temperature, to help keep engine temps down. The hot coolant going to the throttle body is designed to help cold start situations, but also heats the air entering the engine somewhat. Bypassing this will allow for a somewhat cooler air charge. At this point, the car should be running very strong both on the street and at the track with proper tuning. In order to move past this point, more significant upgrades are required.
Instead of focusing on a specific build-up at this point as is common in most "recipes", I am going to stress the importance of a balanced combination. A lot of people have opinions on what works, but it may not apply to every situation. Your best bet is to check with the vendors themselves regarding the application of certain parts. For example, a TA33 turbocharger (essentially a stock hotair turbo with larger compressor and intake turbines) is a very popular upgrade for the hotair cars, and is well complimented by 36#/hour fuel injectors. This is a very common upgrade, and a very effective combo. It does not require extensive headwork or a new stall converter to work well with the modifications above, and is relatively painless to tune because of that. But if you are considering using a larger TA60 turbocharger for example, you may wish to discuss with your vendor what fuel injectors are recommended to compliment this unit. As turbo size grows, you may also wish to look into torque converters with a higher stall speed to help the larger turbo spool faster. Like turbos, certain cam profiles may require the use of a high stall converter. Taking everything into account is the most simple way to build an effective combo, as most vendors list power levels and required stall speeds for optimum performance from the parts you select. New PROM chips will be required as your combination changes, it is typically a good idea to stay with one chip burner as they can modify existing code in a previous chip as your combination changes. Don't forget to tune, tune, tune!!! It is very complex and potentially expensive, but vendors realise this and any vendor worth his salt will take the time to discuss this with you and address any concerns you may have. They may also have suggestions to make based on their experience in the field.
There are a few more areas to address, firstly, the hotair cars have a very poor intake design. It is somewhat of a flaw. The intake should be kept in mind before you start going to very large turbochargers. Some vendors will sell you modified, performance intake manifolds, while some owners give it a hand themselves. Grinding out the runners to the cylinder heads produces noticable improvements, as does removing material inside the intake itself. This may produce a little less air velocity, but vast improvements in airflow at the same boost levels. With this, the cylinder heads may have work performed to them as well. Larger valves, porting, polishing, or complete aftermarket aluminum assemblies can be had. It can be a worthwhile investment to those seeking high output form their engines. More aggressive camshaft profiles are also available, but may affect drivability. Discuss with your vendor for more details and specific cam recommendations.
Both the ECM and the coil pack can be converted to the ‘87-style. This allows for a larger selection of chips, and more available data on a scan tool. It also allows for the use of devices like the Scanmaster and DirectScan scantools, the MaxEffort programmable PROM, and the Translator and Translator +, and it can be done at any point in the upgrade process. It also allows you to run an electric fan to increase the efficiency of the miserable cooling system we have to put up with. A radiator from any V8 G-body may be in order for those living in warmer climates, as may a transmission oil and engine oil cooler. They’ll also keep vital parts alive much longer, as many failures are heat-related. The advantage with converting the coil pack is that replacement ‘87-style packs are much, much cheaper and easier to find in the junkyards, the wiring adapter pays for itself several times over the first time you use it.
Intercooling is a significant power increase for any hotair car. There are kits available, however, it is more and more common to see people designing their own intercooler systems. Some use less piping for better throttle response, some relocate the throttle body, some use front mount intercoolers, some opt for the location used in the later model ('86/'87) cars. There are endless possibilities. You will literally reach the performance limit for the stock internals depending on how radical you go with your build-up, some hotair cars are now in the low 11 and high 10 second range, with an applicable intercooler, they would be closer to the low 10 and high 9 second range, and would be seriously pushing the limits of the stock components. Much more power than this would require a Stage II engine and very advanced electronics.
Alternate injection, such as propane and alcohol injection, are very effective in any turbo Buick. They effectively allow one to use premium pump gas with chips designed for more boost and timing without knock retard or detonation. They increase power both by cooling the incoming air charge and by increasing the octane rating of the fuel. Several kits are available, and some opt to build their injection system themselves. Regardless, they are very effective power adders on any turbo car. Nitrous oxide has also been used, but is typically harder to tune for, as it is only enganged when a little extra (or big extra!) boost is required. But the massive cooling effect and extra oxygen provides potentially huge power increases when properly tuned.
The most important thing to remember when building up your hotair turbo Buick is to tune it. Always! Even if nothing has changed, it can't hurt to throw a scantool on it "just to be sure", no one can be too careful when you invest a good deal of your hard-earned money in something as unique and classy as a turbo Buick. Maintain it well, and it will go fast with class for you for a long time to come.
Always follow basic "spring cleaning" guidelines. Change oil frequently with high-quality synthetic oil. Make sure your spark plug wires are in good condition, and make sure you are using the proper spark plugs for your power level. Most stock hotair cars are best off with stock Delco plugs. Make sure vaccum lines and hose clamps are in good repair. Be sure to change the PCV valve. Set the throttle valve cable, and set the throttle position sensor. Ensure your transmission and differential have plenty of their respective fluids to increase longevity. Neither of these require frequent changes, so you might as well make sure it's done right away, instead of letting any possible problems compound themselves over time. These steps are vital to the proper running of your GN or T-type, especially considering they are almost 20 years old now. The extra attention paid now will pay off in the long run.
We’re going to start by increasing the fueling to the engine. This will ensure we are not running lean, and will add the important factor of tunability to the car. Based on popular opinion and real-world results, the following items can be considered as a necessity when modifying your Buick:
* Walbro 307/340 fuel pump
* Hotwire kit
* Adjustable fuel pressure regulator
This gives us a good basis for future upgrades in regards to adding more boost and fuel. These components are available from several vendors at very reasonable prices, and are able to support a good deal of power. At this level, one should also consider:
* Boost Gauge
* Scan Tool
This will allow us not only to monitor the engines specifics, but will also allow us to record and play back several frames of data. Your scantool is your best friend! For this purpose, either the TurboLink or OTC tools are a real value. Using the information given by the scan tool, we can begin tuning the car for maximum performance and reliability. First, set the IAC. Then, start tuning the idle characteristics, such as BLM and INT (they should be between 118-138), and then you should be ready to start tuning the WOT performance. It is wise to always watch the knock retard and make sure that proper O2 values are being read. Typically, the Hotair cars prefer a little more fuel than the intercooled cars do. I normally tune for just over 800mV at WOT on my Turbolink with pump gas. This gives a bit of a safety net, and still provides a power increase. Try to get it as close to that mark with little to no knock retard (none is ideal). If it is proving difficult, then consider keeping your foot out of it until you complete the next step.
* Adjustable wastegate rod
This gives us the ability to fine tune boost levels as well, giving us much more tuning flexibility. This should allow us to tune for minimum KR and ideal O2 voltages, while providing a good increase in power. If your idle characteristics are optimized properly, then you should be able to use the adjustable wastegate rod and the adjustable fuel pressure regulator to fine tune WOT performance and the car will run great both on the street and at the track.
Standard hot-rodder philosophy would lead us to believe basic induction and exhaust work should come next. Here is where peoples opinions may start to differ. IMO, there are a few good options, but here is what I would suggest based on experience:
* Gutted or no catalytic converter
* Free flowing or no mufflers
* K&N cone or complete induction kit
* Larger downpipe
This is where you can really start feeling a difference in power output. The lower exhaust restriction on the turbo will allow it to spool up much faster, and you should notice a slight decrease in boost level. Grab the scantool and retune, keep checking the idle and WOT settings until you achieve optimum performance with as little knock retard as possible. Always keep in mind, though, the possibility that you may have an exhaust leak somewhere before the turbocharger. It is important to eliminate these before continuing, as they contribute greatly to poor turbocharger performance. You will build pressure more slowly, and your maximum boost level may be severely handicapped. You may need to consider getting your headers welded if they are cracked, or buying new ones altogether. The uppipe and crossover pipe are likewise prone to leaking, and stainless steel replacements are available for a reasonable cost.
Begin to consider upgraded tires or drag slicks at this point, as traction may become a problem. Traction bars are optional, several people are of mixed opinion of them. I believe the stock suspension is a very good foundation to work with, but, like many other things, it's getting old. Replace the bushings with a bushing kit, and be sure to pick up the GNX bushings as well. A longer pinion snubber may or may not help, I have noticed that my pinion is bumping the snubber on high boost launches so I do see a use for it. Airbags are also a good investment, with a few PSI in them, they can help your car float down the road. For racing, filling the passenger side airbag to 12-15 PSI can help keep the rear end planted firmly. Some people box the lower control arms, this requires some welding, but is fairly simple to do. Kits are available from a variety of locations.
Of course, after the long life of our engines, there are some disposable parts which should be replaced as they may be a weak link in making power, such as:
* Valve springs
* Timing chain
The last thing you want is to be flying down the track at wide open throttle and have your timing chain snap. Invest in quality replacement. The valve springs are a notoriously weak link in our valvetrain, so it is wise to make sure yours are fresh or you may experience poor top end performance. A basic top end freshening is a little more insurance in terms of engine strength, and anything to keep your car from becoming a garage queen is welcome!
With all of the proper basic equipment in place, a few other little goodies to enhance performance:
* Performance PROM chip
* Low temperature (160º) thermostat
* Throttle body coolant bypass
The chip will recalibrate fuel, boost, and ignition timing for improved performance. Be sure to do additional tuning after adding this, the different timing, fueling, and boost characteristics could require more fuel pressure or lower boost levels to successfully fight off detonation. The thermostat is rated to open at a lower temperature, to help keep engine temps down. The hot coolant going to the throttle body is designed to help cold start situations, but also heats the air entering the engine somewhat. Bypassing this will allow for a somewhat cooler air charge. At this point, the car should be running very strong both on the street and at the track with proper tuning. In order to move past this point, more significant upgrades are required.
Instead of focusing on a specific build-up at this point as is common in most "recipes", I am going to stress the importance of a balanced combination. A lot of people have opinions on what works, but it may not apply to every situation. Your best bet is to check with the vendors themselves regarding the application of certain parts. For example, a TA33 turbocharger (essentially a stock hotair turbo with larger compressor and intake turbines) is a very popular upgrade for the hotair cars, and is well complimented by 36#/hour fuel injectors. This is a very common upgrade, and a very effective combo. It does not require extensive headwork or a new stall converter to work well with the modifications above, and is relatively painless to tune because of that. But if you are considering using a larger TA60 turbocharger for example, you may wish to discuss with your vendor what fuel injectors are recommended to compliment this unit. As turbo size grows, you may also wish to look into torque converters with a higher stall speed to help the larger turbo spool faster. Like turbos, certain cam profiles may require the use of a high stall converter. Taking everything into account is the most simple way to build an effective combo, as most vendors list power levels and required stall speeds for optimum performance from the parts you select. New PROM chips will be required as your combination changes, it is typically a good idea to stay with one chip burner as they can modify existing code in a previous chip as your combination changes. Don't forget to tune, tune, tune!!! It is very complex and potentially expensive, but vendors realise this and any vendor worth his salt will take the time to discuss this with you and address any concerns you may have. They may also have suggestions to make based on their experience in the field.
There are a few more areas to address, firstly, the hotair cars have a very poor intake design. It is somewhat of a flaw. The intake should be kept in mind before you start going to very large turbochargers. Some vendors will sell you modified, performance intake manifolds, while some owners give it a hand themselves. Grinding out the runners to the cylinder heads produces noticable improvements, as does removing material inside the intake itself. This may produce a little less air velocity, but vast improvements in airflow at the same boost levels. With this, the cylinder heads may have work performed to them as well. Larger valves, porting, polishing, or complete aftermarket aluminum assemblies can be had. It can be a worthwhile investment to those seeking high output form their engines. More aggressive camshaft profiles are also available, but may affect drivability. Discuss with your vendor for more details and specific cam recommendations.
Both the ECM and the coil pack can be converted to the ‘87-style. This allows for a larger selection of chips, and more available data on a scan tool. It also allows for the use of devices like the Scanmaster and DirectScan scantools, the MaxEffort programmable PROM, and the Translator and Translator +, and it can be done at any point in the upgrade process. It also allows you to run an electric fan to increase the efficiency of the miserable cooling system we have to put up with. A radiator from any V8 G-body may be in order for those living in warmer climates, as may a transmission oil and engine oil cooler. They’ll also keep vital parts alive much longer, as many failures are heat-related. The advantage with converting the coil pack is that replacement ‘87-style packs are much, much cheaper and easier to find in the junkyards, the wiring adapter pays for itself several times over the first time you use it.
Intercooling is a significant power increase for any hotair car. There are kits available, however, it is more and more common to see people designing their own intercooler systems. Some use less piping for better throttle response, some relocate the throttle body, some use front mount intercoolers, some opt for the location used in the later model ('86/'87) cars. There are endless possibilities. You will literally reach the performance limit for the stock internals depending on how radical you go with your build-up, some hotair cars are now in the low 11 and high 10 second range, with an applicable intercooler, they would be closer to the low 10 and high 9 second range, and would be seriously pushing the limits of the stock components. Much more power than this would require a Stage II engine and very advanced electronics.
Alternate injection, such as propane and alcohol injection, are very effective in any turbo Buick. They effectively allow one to use premium pump gas with chips designed for more boost and timing without knock retard or detonation. They increase power both by cooling the incoming air charge and by increasing the octane rating of the fuel. Several kits are available, and some opt to build their injection system themselves. Regardless, they are very effective power adders on any turbo car. Nitrous oxide has also been used, but is typically harder to tune for, as it is only enganged when a little extra (or big extra!) boost is required. But the massive cooling effect and extra oxygen provides potentially huge power increases when properly tuned.
The most important thing to remember when building up your hotair turbo Buick is to tune it. Always! Even if nothing has changed, it can't hurt to throw a scantool on it "just to be sure", no one can be too careful when you invest a good deal of your hard-earned money in something as unique and classy as a turbo Buick. Maintain it well, and it will go fast with class for you for a long time to come.