8 cylinder front engine iconic vehicle
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By maddog2020
I've been collecting info for a while on various 928 stroker engines and wanted to post it here so people could start to see data on them.

I'd like to keep this thread technical, data driven in nature. I'm familiar with the engines listed below and will add more data as I scour several hard drives for it.

this is from various forums & in no particular order:

Mike S. 7 liter (640 hp @ 7500RPM 501 torque peak torque between 5-6K) Designed for track use
109mm bore, wet steel sleeves, nikasiled
Custom forged pistons for 10.5:1 compression
94mm custom Moldex crank, LS7 titanium rods
Simard main and head studs
Block halves are 'shuffle pinned'
Dry sumped
ATI damper, Simard lightweight flywheel for 7.25 dual disc racing clutches, hydraulic throwout bearing
Heads are CNC ported with 40mm intake valves and stock 33mm exhaust
Simard 56mm ITB's
Simard gun drilled billet cams with 12.7 lift intake and exhaust
Motec M48 Pro ECU sequential injection & ignition
Pump gas 91 Octane

Louie O. 6.5 liter (603 HP & 6400RPM 531 peak torque between 4300 to 5500) Designed for street use
104mm bore
944S2 pistons 10.2:1 compression.
95.25mm scat crank
TWM 50mm ITB's with Ott adapters
39mm (968)intake valves and stock 33mm exhaust
Devek B1 cams - intake .435 lift 230 dur, exhaust .404 lift 228 dur
Stock lifters
wasted spark coil near plug
Pump gas 91 octane with Alcohol injection @ full throttle

Don H. 6.4 liter (440hp & 478 torque)designed for track use
104mm bore
Modified 968 pistons
95.25mm scat crank
TWM 52mm ITB's with Ott adapters
968 Intake valves with stock exhaust valves
Stock GT cams
Stock lifters
Stock ECU & ignition

John V 6.4 liter (550hp)designed for track use
104mm bore
944s2 pistons
Oliver steel rods
95.25mm scat crank
TWM 50mm ITB's with Ott adapters
968 Intake valves with stock exhaust valves
custom webcams cams
Stock lifters
DTA Pro 8 ecu

Anonomous owner 6.57 (602HP @ 6700 520 torque engine dyno) liter designed for track use
108.9mm bore
Carrillo light weight Greg B. designed rods
93.98mm crank
High Rise intake
968 Intake valves with stock exhaust valves
no piston, cam or lifter info
Electromotive ECU
110 Octane race gas

6.5 liter Designed for street use
86 block bored to 104mm, nikasil plating
JE pistons for 11.5:1 compression
95.25mm custom scat crank
Oliver 5.850 titanium rods
TWM 50mm ITB's with modified Ott adapters
45x50mm oval cylinder head intake ports are CNC ported to 50mm round, with 39mm (968)intake valves and stock 33mm exhaust
Simard billet gun drilled cams intake - .450 lift 226 dur, exhaust .420 lift 220 dur
Lightweight VW black nitrided lifters
Porsche main studs, Simard Head studs
ATI damper, AASCO flywheel, Tilton clutch , Tilton hydraulic T/O
Link Thunder ECU sequential injection and ignition
Injector Dynamics ID725 injectors
VW/Audi coil on plug
Pump gas 93 octane, E85
Last edited by maddog2020 on Thu Dec 31, 2020 1:20 pm, edited 5 times in total.
User avatar
By maddog2020
11.5:1 isn't really considered high compression any more. Tons of production GDI engines are 12:1+. Better control of the ignition and fuel allows for this easily. Using Injector Dynamics injectors as well as COP for ignition is a huge improvement over any other strokers out there using generic injectors and stock ignition.

There are dyno charts around for Simards and Louie's. pretty easy to find. Simards had a really peaky torque curve and louie's was more like a table top. Louie's was especially impressive considering he ran short bell mouths and still got huge torque & he only ran his up to 6400 vs Mikes all the way up to 7500. I know the Motec m48 Pro that Mike used (I actually have one of their ignition expanders required for COP on my desk here) and while it was a great racing ECU in it's time It wasn't much for drivability and I ditched my M48 Pro to go with the new Link Thunder.

AFR will be a variety and is variable. 12.2 for WOT, to 15.5 for lean cruise for gas. (E85 will be different of course)

ECU is capable of blending maps between gas and E85 based on alcohol content. (E85 isn't always E85) Alcohol content sensor also provides fuel temp which also helps the ECU control combustion better.

Link Thunder has a built in MAP for atmosphere and then there is a second MAP that goes to a mini manifold and branches out to the 8 ITB's. I'm using a vacuum pump for the brakes and other stuff because Louie ran into AFR anomalies when he got off the gas and on the brakes hard.

Stock heads flow 275ish @ 500 on the intake side

stock intake ports were 45x50mm oval and mine were opened up to a 50mm round port. (Approximately 10% area increase) other ITB adapters necked down from a 50mm round to an oval 45x50mm in a very short transition to fit the factory intake port shape.

Intake cams are 450 lift 226 duration & my intake port flow is 367.8 CFM @ 28" with velocity of 271.4

exhaust cams are 420 lift 220 duration & my exhaust port flow is 251.7 CFM @ 28" with velocity of 304

Flow numbers above are @ the max lift of my cams, I didn't even keep the data for 500 & 600 lift as it's not relevant.

The cams were a collaboration between Mike Simard and Harvey Crane of Crane Cams. There was a period of time where Crane Cams had gone out of business and Harvey was doing custom cam consulting before he passed away. Every single bit of information was provided from the bell mouth design, intake port length all the way down to measuring the primaries and secondary's on my stepped headers to the distance to the X and the number of bends and radius on the headers. I was even asked for diagrams for the valve & valve seats.

It was a bit of a dance because the guy that did the port and valve work wanted the cam data and Harvey wanted the flow data. Max, the guy that did my heads had access to a wet flow bench used for aviation, and he would take the heads to the facility at night to wet flow them, as he & his brother was allowed to use the equipment after hours for personal use.

Valve seat geometry was a big part of the discussions. Typical engines us a 3 angle grind, and then that graduated to 5 angle grinds, and then there are fully blended valve seats which are used on my current heads.

another thing to keep in mind is that both Mike & louie's were designed with 91 octane and 93 is readily available now.


Thank you for all the feedback. @maddog2020 I […]

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