Holden 186 supercharged engine build

So you are thinking of adding a supercharger to your engine, this is a engine build that may not achieve maximum horse power or performance of a supercharged Holden 6. What it does produce is a reliable street strip package that will perform great in an early Holden. With the development of our supercharger kits for many inline engines it has allowed us to be involved with other businesses and companies. We are publishing one project and hope to publish more of the builds and projects we are involved with. Check back as we add more info to the page.

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This has allowed us to further develop components for greater reliability to be used with the Aussiespeed Range of Performance Products and supercharger kits. We conducted a range of experiments that related to our drive systems including snout support and tensioner. Things like pulley sizes, belt wrap and how the temperature  can affect the horsepower that your engine can put out.


The Recipe/Combination used below may not give you the highest out put but we were happy with the results we achieved. The components listed can be purchased of the shelf. Parts supplied for the build were from

Aussiespeed Performance Products this link goes direct to the Holden 6 cylinder  components page.

We started with a std bore Holden 186 block, the block was hot tanked and then inspected and the bores, deck height from the crankshaft centreline measured, the tunnels were checked and once the inspection was done and the block was deemed suitable the process began. The machine work that was completed on the engine was the same that would be performed by many competent engine shops and considered as reconditioning with close attention to clearances, piston to bore clearance and final hone finish on cylinder bores.

H Beam Conrods.
SPS Forged Pistons 1.68 pin height +40 thou.
These 202 pistons with a 1.68 pin height leave the pistons around 90 thou down the bore in a 186.
Hasting rings
plus 45 thou rings thin style to suit pistons, must be filed to fit.
Camshaft, Lifters, Springs Retainers & Locks
Aussiespeed AS0530 #3 evil stick camshaft.
Aussiespeed AS0529-12 Chilled Iron Lifters.
cam flat tappet hydraulic 232 x 236 @ .050″ .500’lift
Bottom End.
Cam Bearings.
Conrod bearings.
Main Bearings.
Oil Pump New
Alloy timing gear and steel crank gear.
High Volume oil pan.
crankshaft ground to 10/10. If clearances are ok a linish is all that may be required.
Ignition System.
Holden Blue Motor locked distributor.
Ign Bosch HEI with MSD 6AL box.
Plug gap .020″
28 degrees timing total with all tests performed was the optimum with the compression ratio we used. We found that adding more timing did not increase power or performance.
Cylinder Head.
8.0:1 comp
Big valve head 1.680″x 1.440″ small chamber head. Throat ed for larger valves, hand blending of the under seat valve pockets with a die grinder to remove sharp edges. The modified small combustion chamber was originally calculated to be 50cc to achieve our 7.9 to one compression ratio.  After problems with the first cylinder head the chamber volume was machined to a volume of 41.5cc. Valve springs were 140lbs on seat 320lbs open
Roller Rockers 1.6 to 1 Lunati small block chevy v8 rockers.
head gasket cometic .008″
Head stud kit was used. New head bolts should be used if you want to cut a few costs.
Holley 600 DP converted to Boost Reference Pump Gas.
Quick Fuel 650 d/p E85 Blower Carb.

We have used our Aussiespeed big bore headers on the test engine, these are a shorty design pipe with a 2 1/4 outlet. The pipe design uses 1 5/8 mandrel bent primary pipes. The secondary pipe can be varied in length and allows you to complete the system to match the body style of your car.


AS0122 Big bore headers 1 5/8 primary pipe mandrel bent extractors.
AS0039 Big bore 1 5/8 extractors to suit 12 port cylinder heads.

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Once the engine was assembled a few runs were done to bed things in, a few oil changes were done before the engine was lent on.


The great thing about running an engine on the dyno is load can be applied to bed the engine in. You can check for oil leaks, water leaks and run a series of tests on the engine.


We suggest that the first start up and light load run be done with the inner valve spring removed when running dual springs. Once the cam run in is done the inner springs were re fitted.


The first lot of runs were done with a 600 Holley double pumper converted to a blower carb. The 650 Quick Fuel B1 blower carb is a carb we have used many times and find fuel metering and carb adjustments great with the QF carb.


With the the first few runs we found that around 4000 rpm the engine was having a flutter, as we didnt know what the problem was there was no point pushing it harder until the reason was found. We checked every thing distributor, camshaft timing, distributor cap, rotor, carburetor and the miss was still there. Take a guess what it was ? Just about every part on this engine was brand new, 2 faulty spark plug leads were causing it and as they were causing it at various times a drop in torque could be seen on the screen.


There were a few things that didnt go smooth and this was one of them, Cylinder head to block sealing and head gasket play a very important part in boosted engines. The cylinder head was supplied by another shop who we will not mention. The engine had suffered a blown head gasket between 2 cylinders. With the head faced we felt confident we had found the problem.


The cylinder head was reworked by TTT Performance and the chamber design was changed as pictured. The cylinder head chamber design has been used by TTT on both turbo and supercharged Holden six cylinder engines with great results. This whole exercise is to build an engine that is affordable with most components off the shelf.


We used Hasting file fit piston rings .


A of the shelf forged 202 flat top piston was used, with the modified small chamber large valve head TTT Performance got the compression ratio they wanted that allowed up to 15 psi of boost to be run.


Not holes supply oil to the oil rings not grooves like many non performance pistons use. Some of the cast pistons do use this same style of oil control to the oil rings. In 202 Holden engines it was not uncommon for the piston to break through this section even on standard engines.


The inside of the forged piston, its strong but still light weight.

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One of the major thing we found with the the 186 fitted with the Weiand 142 supercharger is how much heat will affect horsepower. With E85 we found a big jump in horse power as the operating temperature dropped considerably. E85 has its benefits and it also has its disadvantages. We didnt get to test it on the dyno as it didnt arrive in time but Devils Own supplied there water methanol injection kits. We have more information down the page on the Devils Own Products.


Quick Fuel E85 boost reference blower carb achieved the best bang for buck, E85 is not available in all areas but its cooling effect made it very beneficial on our supercharged engine. With this carburetor we achieved the highest output.


Quick Fuel 650 B1 boost referenced blower carb for petrol engines, when matched up with a devils own water injection you can get close to the results as E85 but E85 does have an edge in performance.


Devils own water injection kit vacuum operated kit has a dash controller and can have additional features added to the control panel. The kits can be run on Turbo, Supercharged, Naturally Aspirated and Diesel engines.

Stage 2 kit. 1 to 30 psi kit


Water Methanol injection kit switch activated uses all the same components as the advanced kit except it is switch operated. There are 2 different activating switches available. The devils own kit can be added to to run multiple injector points.

Stage 1, Kit 1, is activated for engines running between 2 to 10 psi of boost.

Stage 1, Kit 2, is activated for engines running between 6 to 30 psi of boost.

We will post graphs of the power runs but here is a few bits of data we collected. We did some back to back tests with only a change in fuel on the first to pieces of data that were collected. Same timing, same pulley size same boost, the engine improved a lot with the e85. The third lot of results were the overall best results and is where we did additional changes to get these results.

98 octane pump gas

11 psi boost

256.1 HP @ 5700 rpm

246.5 ft pounds of torque @ 4900 rpm

Degrees of timing 28

E85 Fuel

11 psi boost

293.4 HP @ 5700 rpm

279.1 ft pounds of torque @ 4600 rpm

Degrees of timing 28

Best results over all were achieved with.

E85 Fuel

15 psi boost

305 HP @5800 rpm

295 ft pounds of torque

Degrees of timing 28


We would have liked to do a test with the Water / Meth injection fitted to the engine with pump gas to see how much extra we could have made horse power wise. Unfortunately the Devils own kit didnt arrive in time. 256.1 HP @ 5700 rpm , 246.5 Ftlbs of torque @ 4900 rpm. This is a great street combo and with the right convertor and diff gears would be a good reliable  street strip combo without spending mega dollars.


Results with the engine running on E85

This Video is one of the many runs that were done, 15psi on E85 pump fuel, results showed  305.4 HP @5800 rpm, 295 Lbs torque @ 4900 rpm.

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Polished Holden 6 kit without supercharger

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Full polished Holden 6 cylinder supercharger kit


We will be adding for info to this page and other builds to the website as well.