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WARNING: excessive turbo boost combined with lean mixtures, bad fuel and wrong ignition timing can cause major engine damage very quickly. The Volvo B21FT engine does not have a fuel system with a lot of extra capacity to support great amounts of horsepower without leanning out (lean mixtures mean quick death to a turbo engine). Another weak link is the ignition retard system; it does NOT have a knock sensor to retard ignition timing if detonation occurs. If you can't detect light detonation by ear, don´t use high octane gas, or are not sure about the air/fuel ratio at high boost, do not attempt to raise turbo boost. Remember: "IF YOU GRAB A TIGER BY IT'S TAIL, YOU'D BETTER KNOW WHAT THE HELL YOU ARE DOING!" In this case the "tiger" is boost.

STAGE 0 (165HP) - "Tune up".

This stage covers regular maintenance stuff, if you have taken great care of your turbo motor, this stage will be the easiest!

  • Perform a leak-down test: an engine with more than 10% leakeage needs to be rebuilt, top performance achieved below 3%. If you need to rebuild the engine, consider a B23FT or ´90-on B230FT bottom-end with custom 7.5-8.0:1 compression ratio for more displacement. If your goal is "extreme performance" (way more than 250 HP, using a stronger transmission), then your first stage should be a building super strong (maybe a 2500 cc. " monster") motor with more displacement. Volvo made the parts to withstand 400 HP, you only need to get custom low compression forged pistons.
  • Replace plugs, wires, cap and rotor: NGK BP7ES work very well. A set of high quality low resistance wires are a good investment. MSD wires are good although the distributor boots need to be replaced with straight ones.
  • Index spark plugs (optional)
  • Adjust. initial advance at 12° BTDC.
  • Check the boost retard diaphragm operation by gently applying some pressure from say a bike pump and watch for retard at timing marks. Besides make sure to use hose clamps for these little "vaccum" hoses, boost can blow them off.
  • Clean the fuel injectors: if you have more than 100 K miles and haven´t used very good fuel, it´s a good idea to have the injectors professionally cleaned or replaced. In some cases a good injector cleaner like Techron will do.
  • Clean in-tank screen and ensure both fuel pumps are working correctly (no noises or groans and at least 12 volts at the main pump)
  • Remove intercooler and drain any condensed oil out
  • Upgrade in-tank pump to late model or replacement high volume unit: if your in-tank pump is weak, get a late model unit when replacing it.
  • Backflush fuel pump internal screen: only if you are having fuel delivery problems. The system should flow about 1.8 liters per minute through the return line in the flow test..
  • Check/ clean/ replace oil vapor trap: this is very important since a clogged oil trap will create elevated crankcase pressures that will lead to engine seals failure.
  • Replace the 197°F thermostat with a 180°F unit: the lower temp. will help the engine stay out of detonation.
  • Replace the air cleaner: K&N recently launched the B21FT air filter to the US market.
  • Replace the fuel filter
  • Check and adjust turbo boost pressure (10.5 psi over 4000 RPM)
  • Use premium unleaded fuel only (92+ octane)
  • Synthetic oils everywhere highly recomended (10W30 winter / 15W50 summer)
  • Install a calibrated boost gauge. (The VDO cockpit is a drop-in replacement)
  • Install an Air/Fuel ratio meter. (The Cyberdyne A/F meter being tested by yours truly)

STAGE I (180 HP) - "Airbox modification and Free flow exhaust system".

  • Modify the airbox intake tract: see Jon Glommen´s Airbox Modification article
  • 2.5-3" catalytic converter: if laws allow..... delete the thing from the system!
  • 2.5-3" cat-back system with free flow muffler: a 2.5 inch system and good performance muffler (Walker Dynomax, UltraFlo, Flowmaster, etc) is good for almost 300 HP. Remember that turbo engines need very little muffling to be quiet, straight-through designs work very well. You can even use a 3" muffler even if your exhaust system is only 2.5 inch..

Power gain: 15-20 HP.

WARNING: do not proceed to the following stages if you are unsure about the proper Air/Fuel ratios and detonation recognition. An A/F meter and 95+ octane fuel highly recommended (even higher required under hot weather). Remember that the ignition system in the B21FT is "deaf"(no knock control whatsoever) . Please read this: DETONATION.

STAGE III (195HP) - "Boost control device".

Here is where things get interesting and very delicate. If your engine is not prepared for more boost, you are in for serious engine damage. Detonation and increased exhaust gas temperatures will eat up your engine in no time. Remember, the B21FT DOES NOT have safety systems to avoid detonation. Be prepared to listen carefully for detonation when full boost arrives (specially between 3000 and 4000 RPM). If you hear any pinging, back off that gas pedal NOW! Also remember that weather conditions vary the detonation threshold, cooler weather being much better than hot weather. For example, even if your engine runs excellent in 60 °F weather, it might ping badly in 90 + °F weather. If you would like the engine to take care of itself, there is a safety system that you could install called APC. This Saab system listens for detonation and regulates boost accordingly. It allows the maximum boost the engine will take without pinging. For information on this system, visit the Volvo APC Site.

  • Bypass boost control solenoid
  • Set boost to 13 psi (intercooled models only)
  • Extra fuel: you could use the cold start injector to spray fuel after 10 psi using a pressure switch. The porpuse is to richen the mixture and lower the detonation threshold.

Power gain: 15 HP

STAGE IV (200HP) - "Ignition improvement".

  • Perf. ignition system: our members have tried them all, and the MSD systems are the favorite. The MSD 6AL (RPM limiter) is nice, but the MSD 6 BTM is the nicest of all with the adjustable timing retard proportional to boost.

Power gain: 5 HP

STAGE V (200HP) - "Performance Clutch".

If your stock clutch is just a bit tired, it´ll let you know as soon as you hit 200 HP. Since the M46 transmission won´t hold up at over 250 HP, there is no point in installing a super strong clutch with this transmission, a slipping clutch might help you save the tranny acting as a torque regulator.

  • Centerforce I clutch: a stronger clutch is not recomended because the M46 needs a "torque regulator" to help dampen and survive shock loads under agressive driving.
  • Modified engine mounts: see Adam Smith´s engine mounts modification article.

STAGE VI (220 HP) -"Perf. intake, exhaust and cam".

Notice that we are still at 13 psi, at this stage is where bolt-ons end. However, you can skip this stage is you wish to keep raising boost and managing the fuel and ignition curves. This stage concentrated on improving Volumetric Efficiency,that will let your engine make more power at any boost level and rev beyond 6000 RPM with ease. You need to remove the head to install a better head gasket and maybe o-ring the block for extra reliability. While you are at it, a valve job is a wise decision.

  • B23/ B230 EFI Intake manifold and throttle body: better airflow, it has tunned runners.
  • "A" grind cam and Volvo double springs: this cam can only be found in the B21/B23A and B23/B230ET engines that were never sold in the US. This cam will change your engine´s personality. It broadens the power band by about 1000 RPM, making the engine rev easily to 6500 RPM. It makes the transition from first to second gear (M46 with awfully wide ratios) much better.. Low end torque and idle quality will suffer, but not much (it idles at 17" of vaccum). Advancing the cam 4° helps the low-end torque with almost no sacrifice to the top-end. We are not saying that this is the best cam for the B21FT, just a cam that we have found to work well. We are still researching for new alternatives such as the V, VX, VX3, T5, and custom grinds. If you have any experience and real world data on any performance cam, please drop me a note at: :amorales@chiriqui.com
  • ´90- on B230 exhaust manifold (Part #: 3514440): this manifold needs to be machined for use with the Garret T3 Turbo style turbine housing.
  • High performance head gasket: the Felpro gasket has been reported as being a good performer. The OEM gasket is very good as well, however, get the early non-TTY head bolts for extra torque capacity. Group 6 sells a copper head gasket that is hard to seal with less than immaculate mating surfaces and without weird sealants. The best option for ultra high boost (over 18 psi) is block o-ringing. If you can rent the Iskenderian tool, the block doesn´t need to be removed from the engine. A stock gasket and o-ringed block will hold 25+ psi of boost.
  • Electric main cooling fans: this engine, with the thick A/C-condenser/intercooler/radiator sandwich, needs a very powerfull 16 inch puller fan PLUS a 12 inch pusher to work well. A higher output alternator is needed to power these fans
  • Electronic 5th injector system: your stock CIS injection won´t supply enough fuel for 215 HP. Turbobricks member, Denis L´Espérance, is developing a low-cost, high performance, boost and RPM sensitive injector controller with capacity for 4 extra injectors. HKS, Greddy, Select Sales and others have AIC´s from $320-800. As a cheap alternative, you can use the cold start injector or a small electronic injector (150 cc./min) placed some 10 inches before the throttle body (to aid fuel atomization). You could even install more than one using a separate pressure switch for each one of the injectors. Say, one turns on at 10 psi and the other at 15 psi.

Power gain: 20 HP

STAGE VII (240 HP) - "High boost".

  • Compressor bypass valve: this device will reduce turbo lag between shifts and protect your turbo by avoiding compressor surge. 700 series turbos use bypass valves, that´s one alternative. The aftermarket sells a wide variety of these valves, some of them vent surge pressure to the atmosphere making trick sounds (Greedy, HKS, etc). A good source for new Bosch bypass valves is your local Saab dealer. You can install two of these in high power applications.
  • ADJUST FUEL CUT OUT SWITCH TO 19 PSI: if you don´t have installed the APC system, this is your only safety device other than your sharp ears and right foot.
  • Set boost to 16-17 psi
  • Water injection: an optional safety device.
  • Octane booster or high quality gasoline.

TUNING: unless you have the APC system, you need to carefully tailor your fuel and ignition curves and use high octane fuel to avoid the most feared enemy of any turbocharged engine: detonation. First, you must provide a rich mixture under boost at any RPM. Remember that a right mixture at 5000 RPM could lean out at 6500. A rich mixture is your first step towards detonation prevention. How rich? As rich as it can run without hesitation; in my experience, about 930-950 mV. of O2 sensor output (Bosch 3-wire).

Second, set your ignition timing at 10-12° BTDC if you don´t have any aftermarket boost-retard system. This yields about 26-28° of total advance over 3000 RPM and any boost condition, a bit too much under hot weather, 13+ psi and pump gas. Because of this, use power/boost with caution under hot weather and when using pump gas, if you hear any suspicious noise under the hood, back off the gas now! Another thing to remember: adjust your maximum boost in 4th gear (going uphill preferably) to avoid over-boosting due to boost creep with the pneumatic boost control systems.

Again, you can install an APC system and enjoy the peace of mind. It´ll give you max. possible boost under the prevailing conditions. It´s like having a competitive tuner under the hood adjusting your boost presure, keeping the engine at the edge of detonation. You rest and watch how changes in fuel quality, timing advance, ambient air temp, A/F ratios, etc, move the detonation threshold up and down just by looking at the boost pressure provided by the APC brain.

Power gain: 15-20 HP

STAGE VIII (250HP) - "Upgraded turbo".

Our last real stage, we have cars with this setup and it works very well. An engine prepared up to stage VIII specifications can use higher boost given enough high octane fuel through the aditional electronic injectors. The weak link at this point is the M46 transmission, it won´t survive at over 250 HP. The options are the Toyota Supra and Getrag transmissions with a Centerforce Dual Friction clutch, these are strong enough for 400 HP. For more datails, read Jon Glommen´s transmission swap article.

  • Garret T3, Trim-60 compressor and 0.63 A/R Turbine housing OR T-3/T04 watercooled hybrid turbo (H3-trim compressor & 0.63 A/R )
  • Lower boost to 16 psi.
  • 3" downpipe.

Power gain: 10 HP.

Contributed by: Angel Morales with Jon Glommen, and Anthony Hyde.

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