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Cool Down Your Charge Air! Intercooling the B21FT
by Angel Morales

B21FT-IBS Intercooler Boost System

Here is all the info you need to upgrade your B21FT from 131 HP to 162+ HP using the factory Volvo intercooler system with two variants. First, the "Volvo Boost System" system is not included (it gives 8 psi through 3700, and 10 psi afterwards), instead, the system is adjusted to deliver full boost at all times, resulting in a much fatter torque curve. And second, the A/C cutout system (it disconnects the A/C compressor at 3 psi boost) is not included in this procedure either since it's not absolutely necesary and most people turn the A/C off manually when max power is needed.

Parts pkg. #1

  1. top bracket (P/N 3514143-1) for oil cooler
  2. nut & bolt (P/N 955781-0) with spacer (P/N 949115-0 ) for oil cooler
  3. plug for turbo compressor
Parts Pkg. #2
  1. lower rubber supports (P/N 1317331-5) for radiator and intercooler
  2. fan shroud (P/N 1346434-2)
  3. intercooler (P/N 1317319-0)
  4. top rubbers (P/N 1317330-7) and brackets (#1346446-6) for radiator and intercooler
  5. expansion tank (P/N 1378880) with brackets
  6. screw (P/N 958247) for expansion tank
  7. hose (P/N 942700-6) for expansion tank

Parts Pkg. #3

  1. bellows support (P/N 1357003-1) for air metering unit
  2. hot air pipe for metering unit rubber hose
  3. bracket (P/N 1367045-0) for air pipe bend
  4. gaskets (P/N 463766-6) for throttle housing
  5. studs (P/N 924050-8) for throttle housing
  6. air pipe bend (P/N 1346983-8)

Parts Pkg. #4

  1. small clips (P/N 1357202) for pressure hoses (16 units)
  2. air pipes: (turbo->IC: P/N 8360960-2) (IC->intake: P/N 8360961-0)
  3. pressure hoses (5) (P/N's 3517805-2, 8360988-3, 8360989-1 (2 reqd.), 8360970-1)
  4. clamps (P/N 967764-2 (2 reqd.), P/N 967765-9 (4 reqd.) ) for pressure hoses

Parts Pkg. #5

  1. strip clamp (P/N 948211-8 ) for fuel lines
  2. overboost switch (P/N 1346952-3)
  3. intercooler emblem (P/N 8360990)
  4. 1/4" I.D. vaccum hose (P/N 1306706-1)(10 feet)

Miscellaneous Parts
  1. "T" piece (P/N 8360974-3), 1/4" I.D.
  2. AUTO TRANSMISSION KIT: P/N 8360901-6. Instructions not shown.



Step 1.

  • Remove battery earth cable.
  • Drain coolant.
  • Remove air pipe (across engine) with bracket, connecting hood brackets from throttle housing.
Step 2.
  • Remove clamp on AC-hose. Removing connecting bellows and front protecting plate on air metering unit.
  • Remove air inlet pipe and the hot air hose. Plug or cover all other hoses to prevent contamination by dirt.

IMPORTANT: plug turbo inlet with a rag or piece of newspaper to avoid foreign objects from damaging the turbo compressor.

Step 3.
  • Remove expansion tank and mounting bracket.
  • Remove radiator and mounting brackets.

Step 4.
  • Remove top oil cooler mounting bracket. Drill a new hole as per template (Not provided, but you could drill the hole for best fit after the intercooler and radiator are installed)
  • . Bolt new top bracket, to oil cooler.
  • Remove bottom mounting bracket, turn it 180°.
  • Remount oil cooler to vehicle using new nut bolt with spacer under bracket as shown.

NOTE! Top bracket is mounted to vehicle using new nut and bolt with spacer under bracket as shown.

Step 5.
  • Remove pressure hose between turbo housing and wastegate actuator.
  • Remove right angle connector from turbo housing and plug the hole.

Step 6.
  • Remove strip clamp around the two fuel pipes next to the radiator.
  • Lift carefully and reroute the fuel pipe next to the radiator.
  • Fasten the fuel pipe with a strip clamp to fuel pipe marked "4".
Step 7.
  • Put new lower rubber supports (2 units) for radiator in place.

Step 8.
  • Place fan shroud over fan.
  • Place radiator in position.
  • Mount fan shroud to radiator.
  • Slide intercooler into position ahead of radiator.
  • Mount top rubbers and brackets.
  • Adjust oil cooler air shroud, if necessary, to clear radiator.

Step 9.
  • Bend connecting pipe on radiator about 25° upwards on early models with radiator tank of brass.
  • Do not bend the pipe on later models with plastic radiator tank.

Step 10.
  • Fit expansion tank with brackets using one new screw.
Step 11.
  • Shorten the three coolant hoses accordingly:
    • Upper: 1-3/4 in. (45 mm.)
    • Lower: 2-1/2 in. (60 mm.)
    • Expansion tank: 4-1/2 in. (110 mm.)

Step 12.
  • Mount bellows support on the air metering unit.

Step 13.
  • Reinforce the connecting hose on the metering unit by pressing a piece of hot air pipe into the outlet as follows: Grease the inside of the rubber pipe thoroughly, press the hot air pipe in place and cut according to photo.
Step 14.
  • Fit new bracket with one new gasket on each side to the throttle housing. Transfer microswitch to the new bracket and adjust so that the switch is operated when the throttle is closed.
  • Fit two new studs to the throttle housing.
  • Remove O-ring from old connecting hood and insert it in the new air pipe bend.

Step 15.
  • Fit air pipe bend.
Step 16.
  • Route and connect the long hose (45 in. long, see Step 18) from the hose harness T-piece to left hand air pipe nipple, and fix it to the top of the fan shroud with strip clamps.

Step 17.
  • Re-adjust / replace overboost switch on the foot pedal bracket (to 15 psi)
  • Disconnect cable (blue) to warning lamp at the rear of boost gauge and insulate cable end. Do not reconnect!
Step 18.
  • Assemble the new wastegate actuator hose harness as shown in the picture above. Use 1/4" I.D. vaccum hose only.
Final Step!
  • Reassemble the rest of the system.
  • Fill cooling system with coolant.
  • Connect battery earth cable.
  • Start the engine and check for leaks.
  • If required, adjust ignition setting (12 ° BTDC preferred) and idle CO.

Raising Turbo Boost from 6.5 psi to 10 psi:

You will need a calibrated boost gauge for this procedure. Adjust turbo boost to10 psi by shortening the vent hose (not more than 3 in. at a time), use third or fourth gear for testing. NOTE: you could use a boost control valve instead of the long vent hose. You would place the "T" closer to the air pipe.

IMPORTANT: Do not adjust boost higher than 10 psi unless your engine has the required modifications to withstand higher boost. Severe engine damage can occur if boost is set too high.

You should be doing 0-60 MPH in the low 8's and quarter miles in the high 15's with a stock engine. Still want more? Go to the Staged Mods page for the B21FT.


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