Hot Air Turbo Regal Recipe - Another Flavor
Mike Bonneau
"This information represents what worked for the author(s) with their combinations. It may not work for you. Be aware that anytime you increase the performance of your car you run the risk of damage. Be smart about modifications: take them one at a time and keep a close eye on vital tuning indicators such as knock counts, O2 volts and RPM. This Recipe assumes you are using adequate octane RACING fuel for best performance. -editor"
After carefully examining the technical information gathered over the past several years in respect to the Hotair Turbo Buicks, it has been realized by many members what is really required to make a non-intercooled car move. The following recipe is 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 it is not in good overall mechanical condition, then don’t start modifying the car, as you’ll probably just expedite some form of failure.
The Recipe
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. At this level, one should 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. For this purpose, either the TurboLink or OTC tools are a real value [ed -- DirectScan does not support the 84/85 ECM]. Using the information given by the scan tool, we can begin tuning the car for maximum 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. Try to get it as close to that mark with very little (1-2º) knock retard. 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.

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
  • The ubiquitous K&N cone or complete induction kit

and lastly,

  • I have had excellent results with a larger downpipe, so feel as though I should highly suggest it.

This is akin to the modifications which I’ve done to my car. This is where you can really start feeling a difference in power output. 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.

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. Definitely make sure the suspension is up to par with the drivetrain at this point as well.

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 double roller. 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.

With all of the proper basic equipment in place, a few other little goodies to enhance tunability/drivability/performance:

  • Performance PROM chip
  • Low temperature thermostat
  • Throttle body coolant bypass

The chip one will recalibrate fuel, boost, and ignition timing for improved performance. Be sure to do additional tuning after adding this, the extra timing 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.

I've had success with:

  • Header wrap on up pipe, downpipe, and crossover

You may not want to do this if your pieces are stock, they may result in corrosion of the piping. This is not a problem with the stainless steel replacement pieces offered by some vendors.

After this level of modifications, there are a wide variety of parts available to increase performance. Some vendors offer intercooler kits for our cars. There are a wide variety of injectors, turbos, and chips available. You’d be best to select the performance range you would like to see, and work up a usable combo. For example, a TA-49 turbocharger is a very popular unit, and is well complimented by 36#/hour fuel injectors. This is a very common upgrade. But, bear in mind the limitations and requirements of each. A certain cam profile may require the use of a high stall converter. The type of converter you select will determine turbochargers useful within your power range. The type of turbo that provides enough air will require a specific amount of fuel, so look for injector recommendations with each turbo.

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. 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.

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 you to run an electric fan to increase the efficiency of the miserable cooling system we have to put up with. A V8 radiator may be in order for those living in hotter 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.

So there you have it, a new recipe developed by several hotair enthusiasts. This should ensure maximum output of you hotair-powered Buick and greatly increase the joy of driving it.

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