Let us start at the beginning; the beginning of the air flow and the beginning of most Turbo Buick upgrade projects. The first upgrade is usually the paper air filter to a cotton K & N; or better yet, an open element 9" filter upgrade. The key to ANY turbo engine is air flow. The more you can get out, the more you can get in. The more you get in, the more fuel you will add, the more fuel you BURN, the more power you produce. Yes, the exhaust system is a major contributor in the intake system, but that’s a topic for another day.

The turbo, as we know, is "turbine driven". Exhaust spins the turbine wheel which spins the compressor wheel. This action "compresses" the incoming air into the intake manifold. Packing in more air allows more fuel to be added with a result of much more power. The more air in the engine the more exhaust leaves the engine and the more boost is produced, and so on and so on. (We apologize for over simplifying this for some of you, but for the sake of space we must cut out a couple details.) The K&N open element filter is a good power enhancer because is cuts out quit a bit of draw on the turbocharger itself. {Draw:1. To cause to move after or toward one by applying continuous force; drag. 2. To cause to flow forth.} This small fact allows better spool of the turbo and lessens the resistance on the turbine wheel.

The next BIG power limiter, especially with any larger turbo, is back pressure. {back pressure is just the opposite of draw} Back pressure, once again, includes the exhaust, but not for today. The back pressure within the intake system includes everything from the air filter to the intake valve and combustion chamber. Like any other engine the V-6 Turbo Buick has cylinder heads. The porting and polishing of the heads has a lot of influence on air flow and management. Make the ports too big and you loose air velocity, the key to your turbo engine. This loss of velocity effects throttle response and turbo lag. In most cases you would be better off porting the factory iron heads than going to aftermarket aluminum heads with much larger valves and runners. We know this does not seem correct but please, please, do not get caught up in the bigger is better trap. ESP Products has spent the time and energy to develop a CNC program for the iron turbo head that will carry any properly built engine well into the 10’s, deep 10’s. The 231 engine can only hold so much air and there, like everything, is a point of diminishing returns. 2.02/1.60 valves has gone past that point. The CNC program assures that every head on every engine we build, or you build, is as good as the last. Pick the ESP Strip or ESP Race head program and witness a great increase in power and no loss in lower end torque. I you need to know more details, just contact someone with ESP.

The intake manifold is merely an extension of the head and will enhance the air flow of the cylinder head. Port matching the intake with minor other modifications are all that is necessary for a low 11 second car. The expense of a sheet metal intake and the performance gained per dollar should not be jumped into quickly. ESP Products generally will not recommend these upgrades on stock block engines. Stock block engines are defined as 8 bolts per cylinder head and has no relevance on upgrades such as pistons, bearings, etc,

Throttle bodies have been tested so much lately that we will not go very far into them now. The larger the engine in respect to horsepower the more of an effect the larger throttle body will have. A 65 mm T-Body will have little to no effect on a stock engine, yet may yield 15 hp on a 600 hp engine. In most applications (12’s-11’s-high 10’s) the 62 mm T-Body is just fine. The plenum spacer functions in the same manner, although we have noticed more of an affect on the engines with spacers than the T-Bodies The spacer redirects the air flow to balance the runners, and the 1" thickness increases the overall intake volume to satisfy the needs of all engines as well as the bigger horsepower engines, 500+HP. The 1" thickness also lengthens the runners for improved torque and responsiveness.

The next item of great importance is the almighty intercooler. The stock intercooler in stock application is only 70% efficient. Through the extensive testing we have done, here at ESP Products, we have shown that even a VIRGIN Grand National / T-Type can still gain 30hp by this simple bolt-on. This translates to 3 tenths in the 1/4 mile. Now this should not be the goal for any frontmount intercooler, although that is the best for some of them. Modified neck stock unit generally pick up the engine 10-15 hp due to air flow improvements. Stretch units generally pick up 20-25 hp due to both air flow improvements and greater heat transfer area.

The intercooler has more of a purpose then just cooling charged air to the intake, it also must reduce back pressure. Why? Jumping back to the beginning of the article, exhaust drives the turbine and the compressor pushes incoming air through the intercooler into the throttle body. The resistance to this is called back pressure (simplified). The back pressure has a two part affect that you may have never consider.

1st - The charged air going through the intercooler meets with resistance and results in both lower boost levels at the intake and super heated charged air (higher intake temperatures). The lower boost levels, because it just can not get through. The higher intake air temperatures, because in the compressing of the air heat is created. With this back up at the intercooler you are compressing the air over and over until it can get through the intercooler.

2nd - You should not forget that the turbine and compressor sides of the turbo are DIRECTLY connected. What ever happens to one side happens to the other. If the compressor meets with resistance resulting from the above reasons then the turbine is effected by that resistance. The result is the turbine spins slower. The exhaust drives the turbine and the resistance encountered backs up the exhaust between the turbo and the cylinder heads. This HEAT in the manifolds creates substantial under hood temperatures and causes the air filter to pull in hotter air. The exhaust that can not escape from the cylinder heads, obviously remains there, dilutes the incoming air both by volume and temperature. The exhaust stuck in the cylinders prevents intake air from entering the cylinder and in addition the cool incoming air is mixed with the hot exhaust left behind. Consider the RPMs and how often this occurs and the resulting domino effect. The escalating heat in the cylinder heads is a direct cause of engine detonation (pre-ignition).

A crude way to test the intercoolers effectiveness is to run an aftermarket boost gauge at the intake manifold, try the fuel regulator line or the MAP line. Note the boost level. Now change the location of the boost gauge source to the turbocharger fitting directly on the compressor housing. Note the increase in boost. This difference is the amount of boost lost through your intercooler. This also represents the back pressure on the exhaust side. Why work so hard upgrading to a dual exhaust system and a 3" downpipe if you have that back-up in the turbo, the very beginning of your exhaust system?

When you take a good intercooler that offers excellent air flow and heat exchange properties, you can gain upwards of 60+ horsepower. The intercoolers that come close to this are frontmount intercoolers. For power, this is it. Why? ESP Products, though actively testing, can share the following information in regards to air management and its affects on overall performance.

During recent and ongoing tests we have relocated a MAT sensor (manifold air temperature) to the inlet pipe just before the throttle body in order to get a true intake temperature reading. Did you ever wonder why the factory placed the MAT sensor nowhere near the manifold? Well, these are the results.

Condition At filter/ At T-Body/

40-45° day Water temp Water temp

Idle 87°/156° 65°/153°

Cruise (60 mph) 87°/157° 47°/169° *

In town 95°/158° 50°/158°

* vehicle was run under boost to raise water temp for test purposes.

You can see a difference of up to 45° in air temperature. The purpose of this test is to show how you can affect your fuel management by fine tuning your air management. The cooler temperature read at the throttle body will be sent to the computer and a more accurate A/F mixture will be realized. This test was done on a quick trip to the machine shop and is just a sample of what we have seen. On cooler days the effects were even greater.

How can this FREE horsepower be acquired? We suggest the following...

...aluminum MAF pipe, aluminum inlets pipe, relocate your MAT sensor, frontmount intercooler. The aluminum helps remove heat from the intake air, that’s important to remember. You’re heating the air after the turbo by compressing it and this pathway should NOT be wrapped or coated in any way. For efficiency, we like to keep the total intake system, that carries only air, all aluminum. If you paint an intercooler face to camouflage it, be light with the coat. Do not powdercoat or ceramic coat the intercooler or pipes. (Coating the pipes will yield the opposite results and retain heat within the pipes.)

Another tip is a 4" MAF pipe. Even with turbos that have 3" inlets, this 4" aluminum tube will reduce the draw placed on the turbo and allow a freer spin, so to speak. Now that the larger LT1 MAFs are becoming more popular the 4" MAF pipe make even more sense. For those of you with DFI or Speed-Pro Systems the 4" pipe offers maximum air flow.

One last note with regards to the turbo, back pressure, and draw. These properties have a direct effect on turbo longevity. Excessive limits of both causes wear on turbo thrust bearings. Thrust bearing failure is a common failure area for performance turbos. Turbonetics has developed a ceramic ball bearing turbo which is 50 times stronger in this area. The side effects of this ball bearing design are more power, quicker spool up, and reduced turbo lag. You can also manage the air flow with a "sneeze" valve. We covered these in another issue and will not go into the benefits right now. As always we are happy to consult you and answer any questions you may have regarding these and other topics having to do with the Buick Turbo V-6.

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