"Making Turbocharger Technology Work"
BMW M3 Turbo Systems
BMW E36 M3 Intercooled Turbocharger System
After the fourth iteration of forced induction BMWs, with almost every conceivable blower type, we simply cannot justify, either technically or functionally, any other mechanism than the turbo. We have unhesitatingly set our sights on building the best spare no expense system that twenty-five years of experience permits. It is quite evident that the best had to have the turbo.
At the outset, we had no specific agenda regarding blower types, eventhough we have been producing turbocharger systems for various BMWs over the last 25 years. The perception after one trip around the block in an M3 with a centrifugal supercharger (CS), clearly showed that it was not an acceptable machine. This system was built by the current top dog, and is representative of the best offered today. After months of evaluation of the fixed displacement blower, we concluded this approach offered the best performance available under 2000 rpm, but real power was going to be very illusive. 2000 rpm is not the performance range that fast motoring is all about. When the complexity and cost required of the fixed displacement blower installation was summed up, the low rpm advantage was not considered worth the trouble and expense. Then came the turbo. The whole spectrum of performance of the turbo just came alive and easily proved vastly superior to our experience with the CS. Except for boost below the 2000 mark, the turbo performance so badly eclipsed the fixed displacement blower that our path to the intended performance was clearly spelled out.
We had many objectives in mind when designing this system. Simplicity and serviceability were of urgent priority, but the two greatest objectives were; first, to weed out all the fussy little problems that have thus far kept forced induction systems for the BMW from being either acceptable or successful. Second, to build a system technically and functionally correct. The simplicity, elegance and component quality of M3 turbo solve all these problems and create many happy owners. The performance of the turbo will create even more incredulous owners. The long term durability and fuss free operation of the turbo will produce a whole new cadre of firm believers.
We designed and patterned this manifold completely from scratch. Styled after the Offenhauser Indy car manifolds, this ductile iron casting is extremely strong, yet not overweight. The decision to use a casting and ductile iron as the material is prompted by the desire to have a high-quality and high-durability piece. The design is slightly conical from the port to the turbine entry and thermal expansion is carefully controlled such that thermal warping is eliminated and straight line expansion assured. This manifold will flow well up to rates equivalent to 600+ bhp. The T4 turbine flange is machined precisely to eliminate the usual gasket. The manifold comes to you with a proper thermal coating. No paint. Stainless steel fasteners are provided to hold things together.
The Tial unit is a CNC billet aluminum top and stainless base. It's a race quality item with the highest temperature diaphragms available. We have integrated the gate into the system in a very interesting manner. We utilized a layout similar to the Toyota IMSA GTP racers of a few years back (arguably the most successful turbo endurance racing effort since the 917). This gate configured to be compatible with modern remote controllers. A Cartech boost gauge and Greddy Profec-B electronic boost controller are also included in the system.
The Garrett Airesearch TO4 series turbo is the real workhorse of the industry. The Turbonetics 60-1 is the starting point and provides nearly infinite room for growth as engine modifications dictate. It has been kept modern with the latest in high efficiency compressor wheels and shaft seals. A ball bearing version is the leading choice for our system. We also like it for the extreme durability it offers. A water cooled bearing section is available and adds even more life. A choice of three turbines, six compressors, and five different A/R ratios gives us the opportunity to size the turbo right on for the end users needs.
Turbine Outlet Pipe (downpipe):
The stianless TO pipe is 3.0 inch in diameter and ideal for power outputs to 600+ bhp. Weve put the wastegate dump back into the exhaust far down the pipe to avoid the power robbing turbulence right behind the turbine.
Compressor Inlet & Intercooler Tubes:
All tubes are fabricated from high quality mandrel bends, bead rolled on the ends and powder coated with black wrinkle finish. Alternate finishes are available at no additional cost. Silicone material hoses are used throughout, and, on the pressure side, retained by stainless cross-bolt style clamps.
Air Filter Assembly:
Generally one does not consider an air filter as a major component. This time, it's different. Three severe problems exist with the installation of the air filtration system for the M3. Inadequate space for a proper size air filter (160 square inches, minimum) and we've nothing but the atmosphere to push the air into the turbo, hence flow losses are potentially high. The space problem is solved by using the space the factory chose for the original air filter.
The intercooler is an aluminum fabrication sized for approximately 500 bhp.
We use bar-plate cores which yield the greatest
efficiency at the lowest pressure drop. These are the very same cores that Spearco chooses to sell. We also decided to utilize a vertical charge flow
configuration to increase the internal flow area and reduce the internal
friction of a typical horizontal flow configuration. The air temperature going into the engine, as
stated so often, is the key element in deciding life or death for a forced induction
engine. The hotter the air, the sooner knock sets in, and knock is hugely destructive.
Further to the safety benefit is a virtually free 12 to14% gain in torque due to the
cooler, more dense air. The sanity of not having a proper intercooler in any supercharger
or turbo system can only be explained by the makers accountant and sales
staff. It is fundamental engineering that an intercooled SC system is both safer for the engine and
more powerful than a system that has no
Anti-Surge / Bypass valve:
The by-pass valve is an air diverter when cruising
so the blower or turbo will not need to make boost
that would only pile up on the throttle plate and load up the blower. A nice touch that
all OEM system have. We have adapted a
Our system utilizes the factory DME for both OBD I and OBD II systems. We have spent countless months of chassis dyno time to get you a completely reliable and very powerful engine map (a Clayton variable load dyno for those interested). A standard voltage clamp is provided to maintain the drivability and excellent street manners. Also a complete set of injectors is included to compliment the power level and turbo selection.
We would like to suggest that most are looking for the best combination of the following facets of performance:
Our contention is that the turbo wins every category, hands down.
Why the Turbo?
Shape of the torque curve:
Please understand, that is what you get with the centrifugal blower, but we strongly suspect it is not what you either want or think you are getting with a supercharger. Wouldnt it be a hoot if someone invented a way to let the same compressor wheel speed up relative to the engine so more low engine speed boost could be produced? Such a device exists and it is the turbo. The key to this great turbo performance benefit is that it can change speeds independently of the engine.
The net result is this: The turbocharger applied to the BMW M3 can produce all of it's boost by 3500 RPM.
Power = Po x PR x DC x Evol Ratio x PL
Boost + 14.7
DC is the density correction due to heating of the air charge. This is directly proportional to the absolute temperature of the ambient air to the boost air entering the engine. At 7 psi these corrections are about .85 without an intercooler, and about .96 with the IC. Our systems operate at 8.5-9.0 psi, however we chose the lower boost number for comparison purposes.
Evol is the volumetric efficiency ratio of the blower to the engine. Since the CS and the turbo have the same Vol Eff, and the engine is the same, this factor can drop out. Assuming comparable compressors are available.
PL is the power loss correction due to the necessary power taken from the crankshaft to drive the blower. Here the CS takes about 5% of the engine power, whereas the turbo only robs about 1.5%. The reason for the difference is that the turbo is largely powered by the heat energy in the exhaust gas. Keep in mind that the heat energy lost out the tailpipe is about the same number of horses as the engine makes. Remember, of the fuel burned, 1/3 goes to power, 1/3 to heat in the cooling system, and 1/3 out the exhaust. Therefore the lost exhaust energy and the engine power are about the same. When was the last time you saw a 240 hp fan? That is what is made available to the turbo for a driving force without taping off the crank. We dont need it all, but thats whats theoretically available. Enormous, eh?
So, plug the numbers in and see what they yield:
P = 240 x 1.49 x .85 x (1-.05) = 289 bhp
P = 240 x 1.49 x .96 x (1 - .015) = 338 bhp
If you can do a back to back test on two real cars, those are very close to the numbers you will get. One wants to ask all the obvious questions of all the CS claims of 340 bhp at 5 psi without an intercooler.
Lets Talk Value
for a Second
* Some of the CS systems cost over $9,000, but the equation remains the same.
Notice the difference in power gained between the two systems. The CS gains 49 hp and the intercooled turbo gains 98 hp. That means the turbo gains 2 times the power the CS gains.
But I cant stand the lag!:
the Turbo versus the Centrifugal Blower
The Turbo Heat
When an SC salesman tells you his system is so well engineered that an intercooler is not worthwhile, its time to question his motives. While his argument may sound plausible by citing that the blower doesnt make heat, or that intercoolers have bad side effects, this is simply not what physics bears out.
The engine safety of our system is well under control. The turbo and the CS generally share the same style compressor and are therefore, equal in efficiency, which means they produce the same heat in the air charge. The similarity stops right there. Our intercooler removes 88% of the 120 F added by the turbo, at around 7 psi. This intercooler is such a powerful influence on the temperatures, that the turbo could produce over 30 psi of boost before the air temperature exiting the intercooler would be the same as that exiting the centrifugal blower. Further engine safety is provided by the correct air/fuel ratios and the original factory knock sensing system, via our reprogramming of the DME. Follow the rules regarding fuel octane, standard premium grade, and the safety issue is a slam dunk.
Mid-range pulling ability of large engines has always been their attraction. This characteristic now shows up in the Turbo BMW with its new found torque capability. We hope the idea of calling the M3 a low and mid-range torquer doesn't sound too preposterous. Before laughing and rejecting the idea, please accept and regard as fact, the Turbo BMW will pull harder in 5th gear at just 3000 rpm than the stock BMW can manage in 3rd gear, at virtually any RPM. Further along the same idea, 3rd gear under boost will accelerate over 10% faster than 2nd gear stock can manage. It sounds preposterous perhaps, but it is absolute fact, the Turbo BMW M3 will do exactly that with the equipment provided in our system. And it does so safely.
Along with the sheer fun and entertainment value of the huge power and torque increase, comes the capability to properly decorate your favorite strip of pavement with long black lines. This is particularly fun as the Turbo BMW M3 never looses its composure and accomplishes such feats with true grace and ease.
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