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"Vintage Triumph Pre Unit"

Vintage Pre Unit Triumph Engines

Our high performance Pre-Unit Triumph engines are ​built ​for racing purposes. We build specific engines for specific Land Speed Racing classes. These are the most powerful LSR engines ever built on a Triumph pre-unit platform.​

These engines can come with our Land Speed​ Racing​ frame and all the ​required components to achieve what you are aiming for.  Our Triumph pre unit construction

frame is designed according to our high performance engines and are a big part of our success.


Parallel twin British Motorcycles are known for vibration, especially the vintage pre unit Triumph rigid frame. After many race and test runs we've figured out the best frame geometry and the perfect ​engine ​balance factor. 

All our crankshafts are specifically balanced  to our standards according to the frames they will be used in.​

The smooth revving Triumph pre unit engine is key to efficient performance. The results speak for themselves!



Alp Sungurtekin Pre unit Triumph Engine Rebuild
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Alp Racing & Design 650 Vintage Class "Pre 56" Engine Specs:
  • OEM Pre-unit Triumph 6T Crankcases

  • MAP Connecting rods

  • OEM Triumph crankshaft, modified and balanced by Alp Sungurtekin

  • OEM Cast Iron Barrels

  • 2.795" bore, 3.23" stroke

  • Original Hepolite pistons modified and balanced by Alp

  • 13:1 compression ratio

  • OEM 1950 Triumph 6T iron head, ported/optimized by Alp

  • OEM  pre unit oil pump.

  • Modified oiling system by Alp

  • BNR Primary drive and clutch

  • Dual Amal 32mm Concentric Carburetors or 1-3/8" Dual Amal GP's

  • Morris Magneto 

  • Pre unit gearbox std ratio

  • On 110K Racing Gas 60+ Horsepower.

  • On 98% Nitro-methane 150 Horsepower estimated

  • Top speed 141mph Gas

  • Top speed 180mph Fuel - 09/17/2018 Bonneville "World of Speed"
    1950 Triumph Frame 1952 Triumph Ironhead engine class M/VF 650


Alp Racing & Design 650 Pushrod Class Engine Specs:
  • Thunder Engineering Triumph pre unit crankcases and rods.

  • OEM Triumph crankshaft, modified and balanced by Alp Sungurtekin

  • Triples Rule Barrels, Custom made 650cc with plain cast iron sleeves from Northwest Sleeve.

  • 2.795" bore, 3.23" stroke

  • Robins pistons modified and balanced by Alp

  • 13:1 compression ratio

  • OEM 1964 Triumph T120 cylinder head, ported/optimized by Alp

  • OEM pre unit oil pump.

  • Modified oiling system by Alp

  • BNR Primary drive and clutch

  • Dual Amal GP 1-3/8 Carburetors

  • Morris Magneto

  • Pre unit gearbox std ratio

  • On 98% Nitromethane

  • 150 Horsepower estimated.    Top speed 175mph - 11/14/2015 El Mirage, CA SCTA class A/PF 650



Alp Racing Engine's Records Documentation & Certification HERE 

Pushrod & Vintage Class Engine Rules HERE


VIDEO of the 175.625MPH Record run at El Mirage, CA

Cam Timing Triumph Pre Unit
Nitro Triumph Pre Unit Engine GP Carbs
Ironhead Triumph Pre Unit Rocke Box Rebuild
Alp 650 Triumph Iron Cylinder Head

Stage 3 Full Racing cylinder head for the SCTA & AMA Vintage LSR classes. 1950 Triumph 6T cast iron ports welded/brazed and flow optimised for dual GP's. This is the cyl. head & configuration that achieved the record speed of 169.936MPH at its first run right after built by Alp at the El Mirage dry lake in July 2016

Top Fuel Pre Unit Engine Alp

Testing mechanical fuel injection pre unit engine for client. Top speed 172MPH

Ironhead porting cyl head 2012

Optimising ironhead ports, Stage one (without pre welding)

alp r-d honing cylinder guides on a ironhead

alp r-d honing cylinder guides on a ironhead

alp r-d honing cylinders to final size
Specs Book

Specs Book

Precision Honing

Precision Honing .0001" Mitutoyo

Modifying Triumph 650 Crankshaft

Modifying Triumph 650 Crankshaft

Modifying Triumph 650 Crankshaft

Modifying Triumph 650 Crankshaft

Camshaft & Flywheel

The Devil is in the detail!

Getting Ready

Alp's Engine Workstation

Valves Spring

Alp's Engine Workstation

650 Barrels Crankcases

Alp's Engine Workstation

650 Ironhead Rockerboxes

Alp's Engine Workstation

Balancing Connecting Rod

Balancing Connecting Rods

desk cyl heads alp

Long Nights

Pre Unit Rocker Arm Pushrod Geometry

The perfect X

650 Thunderbird Ironhead

Verifying Deck Surface

Modified Cylinder Head

Verifying Compression Ratio

Ironhead Pre Unit

Checking Valvetrain

High Compression Hepolite Pistons

Piston to Valve Clearance

Play Doh Helps

Verifying Piston to Valve Clearance

Thunder Engineering Crankcases and connecting rods

Thunder Engineering Crankcases and Connecting rods that we use in the Pushrod Fuel Class

Alp A Frame Primary Belt Drive
Alp Racing Amal Carbs

Amal Carburetors from Burlen Fuel


AMAL GP's and Matchbox Fuel Floats

Alp 650 Racing Engine

Top Fuel Pre Unit Engine

alp 650 pre unit custom engine

Pre unit engine with Monoblock Carbs

Alp custom pre unit engine 1956

650 pre unit engine Monoblock carbs side view

Pre unit cylinder head polished

1956 Pre Unit Cylinder Head with Rocker Boxes

Rebuilding the pre unit Gearbox

Pre Unit Gearbox Rebuild

Liquid Horsepower

Getting Ready for the Next Race

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