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B26FT Stroker
Volvo Turbo Engine Project


     UPDATED: October 25, 2020                    CONTACT       
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  Here are some pics of my original stroker project completed in 2001.



This project was born out of a desire for more low-end torque out of my 245Ti.  Boost is nice and certainly effective, but I decided that a base of 2.1 liters is just not enough... not for me.  As it turned out, 2.3 liters is not enough either!  But rather than mess with something as complex as a V-8 conversion, I decided to keep the Volvo motor.  I believe in Volvo motors.  They are such sturdy hunks of iron with so much potential.  I just don't particularly believe in original specs.

This purpose of this project was to produce a bored and stroked B23FT with
2630cc of turbocharged, Volvo torque!
Update:  A dyno session in 2005 produced a rear wheel torque
 measurement of 323 ft lbs at 3200 RPM (18 PSI boost with 100 octane fuel)

This project began with the purchase of a used B23FT junkyard motor in January 1999.
This custom engine was completed and installed in April of 2001.  

When I started this, I had originally planned to use the stock K-Jetronic fuel injection since I did not think at the time I could afford (or figure out how to install) a decent aftermarket EFI system.  I considered a stock EFI system from another Volvo but dropped it because of it's inflexibility.  This was many years before less expensive EFI alternatives were born, like Megasquirt.  But... since I eventually decided to go to the trouble to fit an EFI, I wanted it to be something more programmable.  What I ended up with was a complete and fully programmable aftermarket EFI system from Racetech - SDS (Simple Digital Systems).  They have a web site that fully explains this system.

Fuel injectors are 550cc Lucas units from RC Engineering in Torrance, California.

I had had a custom all-aluminum intercooler fabricated for use in this project.  It was made to my specs by Spearco Intercoolers.  It's really massive. This intercooler was basically made to OEM 240 Turbo intercooler dimensions, except that it's 3 1/2 inches thick.  



Turbocharger was a Turbonetics "Super 60" (T-3 based) bolted to a later style turbo exhaust manifold.  It had a 60 trim compressor wheel and .63 A/R turbine housing.  Performance was pretty good, but the exhaust turbine came apart after about 2,000 miles.


Here are some pics of the damaged exhaust turbine and the pieces I found in my exhaust pipe.
After that mishap, I moved to a standard T-3 turbo from a 240 Turbo, because I had one laying around.

Specifications for this Project:

Block: 1984 B23FT, bored from 96 to 97 mm (3.818").
Click here for "BEFORE" picture
Click here for "AFTER" picture
Deck Height: (Crank CL to deck) 231.685 mm (9.121")

Why bore the block to 97 mm?
The stroker parts supplier (no longer in business) sold me 97 mm pistons and claimed to be highly knowledgeable in Volvo race motors.  He insisted that boring a B23 to 97 mm was never a problem for him.  I have since discovered that boring a B23 block past the 96.6 mm second bore spec is NOT recommended.  The reason for this is because of a design problem common in many Volvo B23 blocks where the core had shifted slightly during the casting stage.  This made the cylinder wall thicknesses uneven and thin in some spots (sometimes... not always).  If one of these thin-walled blocks is bored too much, the cylinder wall becomes dangerously thin and would be prone to cracking.  This has happened several times to fellow Volvo enthusiasts who have tried a 97 mm bore.  I consider myself very lucky that my block hasn't cracked.  If you are unsure about your B23 block, you should have a Sonic Test done by your machinist to determine cylinder wall thickness before boring.  I have been told that a minimum thickness of 0.100" (2.5 mm) is recommended for a turbocharged engine.

Pistons: WISECO forged.
Bore: 97 mm (3.818")
Compression Height: 30.785 mm (1.212")
Wrist Pin Diameter: 22 mm (.866") full floating
Reverse Dome: 12cc dishes (reverse domes) with 4 mm radius at bottom.  10 mm (.400") "squish band" retained around edge.  This dome was done for me by Wiseco after I bought the pistons.  Sounds kind of backwards, I know.  I had no choice as the pistons sold to me were the wrong configuration and needed to be re-configured for the stroker design.


Assembled Deck Height: 0.40 mm (.016") below deck.
Squish Height: 0.056" using Cutting Edge head gasket of 1.0 mm (.040") compressed.
Update on Squish Height: This squish height dimension has turned out to be excessive.  It was used at the strong recommendation of Pauter Machine, who supplied the connecting rods.  They didn't know better and neither did I back in 2000 when this was done.  A better squish height would have been to set the pistons to be at or just above the deck at TDC, to a max height of 0.012" above the deck.  My next motor will use this configuration.
Piston Source: WISECO PISTONS, INC. , 7201 Industrial Park Blvd., Mentor, Ohio 44060, (440) 951-6600,  http://www.wiseco.com/


Piston Side Clearance Issues:
When my engine was being completed, I had the machine shop set the piston clearance to the supplier's recommended figure of .004" (four thousandths).   Consequently, the pistons make a clatter noise when cold (piston-slap) and still some noise when warm.  I have since learned  that .004 inch is a bit much.  Mike Aaro of Unitek in Sweden recommended the side clearance for a forged street-driven piston of .0018 to .0020 inch (eighteen to twenty ten-thousandths).  For your project, you should consult the piston designers for these specs..  

Connecting Rods: PAUTER "X" beam, forged E4340 Chrome-Moly steel.

Length (Center to Center): 6.140" (156 mm)... 11 mm longer than stock "M" rods, which are 145 mm.  These custom rods give the motor a rod to stroke ratio of 1.75:1, which is a little less than stock (OEM is 1.81:1 ratio).
Small End dia. (wrist pin): .866" (22 mm)
Big End dia.: 1.8897" (48 mm)
Small End width: 1.120" (28.448 mm)
Big End width: 1.164" (29.565 mm)
Big End weight: 485 grams
Overall weight: 696 grams
Rod Bearing: (Listed below with crankshaft specs)
Source:  PAUTER MACHINE CO., INC.
367 Zenith St., Chula Vista, CA 91911
(619) 422-5384    FAX (619) 422-1924
http://www.pauter.com/

Crankshaft:
OEM B23 forged steel crank.  Rod journals have been offset ground for increased stroke from 80 mm to 89 mm (3.503") stroke.  The journals were reduced from 54 mm to 45 mm.  The main crank journals are original size (63+ mm).

Rod bearings used for this project are as follows:
Clevite CB-1120P (full specifications below)
Shaft diameter (crank/rod journal): 1.7710-1.7717" (44.9834-45.0011 mm)
Oil clearance:  .0006-.003" (.0152-.0762 mm)
Bearing wall thickness:  .0588" (1.4935 mm)
Housing diameter (rod big-end):  1.8897-1.8905" (47.9983-48.0187 mm)

Some OEM Crank Main Journal/Wrist Pin Dimensions Courtesy of Mike Aaro
First generation "red" engine (B18/20/21/23/230, 1961-1984/85) main bearing size is 63.454 mm nominal (integrated axial bearing). Wrist Pin is 22 mm (1961-1972) and 24 mm (1973-1984/85).
The second generation main bearing (1985-1988/89) is 55.000 mm nominal (separate axial bearing). Wrist Pin is 23 mm.
The third generation and final (1988/89-1998) design was 63.000 mm nominal (integrated axial bearing). Wrist Pin is 23 mm.

Head Used for this Project:
<<< "1000398" casting with 3/85 date code (small coolant passage).
 
Combustion chambers opened from OEM 51.7 cc to 59 cc. 

Chambers were re-shaped slightly and valves unshrounded. The actual template used by my machinist is shown at left (measurements in this photo are in centimeters). 
<<< Here is an image of the #4 combustion chamber (measurements for this photo are in 10ths of an inch).


Valves: OEM turbo valves (Stellite faced, sodium filled exhaust) and the later style OEM valve springs were used.



<<< This shows a comparison between the OEM combustion chambers (51.7 cc) and the modified ones (59 cc).  Also, it's easy to see the difference between the big coolant passage (BCP) head and the more desireable small coolant passage (SCP) head.

Why is the Small Coolant Passage head better?  It is considered to be a stronger design that is less prone to cracking.
When did this change occur?  One Turbobricks subscriber wrote: "I have a 398 head that is BCP dated 3/3/84... and a 398 head that is SCP dated 4/12/84."  I also have a SCP 398 head I pulled from a Pick-A-Part that is dated 4/4/84.   Obviously the change occured between March 3 and April 4, 1984.
Where can you find the date code?  It's molded into the aluminum on the exhaust port side very close to the back of the head.  The numbers are vertical, i.e.: for my 4/4/84 head, you can see a "4", then below that a "4", then below that an "84".

Head Gasket:  The head gasket I used was the "cutting edge" type, which actually has a hardened steel fire ring that cuts into the soft aluminum and seals the head.  It's designed for very high combustion chamber pressures and is 0.040" (1 mm) thick when compressed.  In comparison, a stock Volvo head gasket usually runs about 0.050" to 0.060" (1.25 to 1.5 mm) when compressed.  The CE gasket is very expensive (about $300) and considered to be the best gasket made.

Compression Ratio:   The above combination (using a head gasket with 1.0 mm/.040" compressed thickness), has a 9.4 to 1 Compression Ratio.


Camshaft:  The camshaft I used for this motor is the Unitek Phase One.  It is an aftermarket cam that works very well with a turbocharged engine.  It has almost 12 mm of lift and very short duration.  It completely blows away other cams I have experienced.  It may be ordered from Unitek in Sweden.

Machine work done by:
Greg Landes
Millenium Motorsports, Temecula, CA
951-699-1889




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