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Twinscrew supercharged Astra MK3

11K views 53 replies 37 participants last post by  Astra 16v SC 
#1 ·
I get a lot of questions about my car through emails, so I decided it's time to start a thread and tell you guys a bit about it.

I have owned this car since June 1998, 3 owners (including me), it has about 90.000 km on the meter, only used summertime and it still got the original paint job.

First time supercharged in 1999 with the ENEM/Lexmaul kit wich later on was modifed with an intercooler and MBE 967 injection.

First own designed supercharger kit installed in 2002.

Current engine:

Based on a C20XE –88. Balanced and weight adjusted. Late-spec crankshaft from Astra GSi MK3 -92. Block O-ringed. Mahle forged low compression pistons, 9.0:1. AutoVerdi steel conrods. ARP pinbolts. SBD oil pump with steel gears. SBD nylon oil pressure relief valve. Balanced and modified flywheel from Astra GSi MK2 16v. 12-9 quality flywheel bolts. Ported coscast head. Group A valve springs. ARP head pinbolts. Special three layer steel headgasket. C20XE cams. CNC-modified inlet from Astra GSi MK3 16v. ETC throttle house removed and replaced with a CNC-machined supercharger-adapter in billet aluminium. Lysholm 1600 twin-screw supercharger. Single throttle house from Omega 2,6i. K&N air filter. Custom built intercooler for high efficiency and low pressure drop. HKS racing recirculating blow off valve. TWM fuel rail. Bosch low impedance fuel injectors, 584 cc @ 2,4 bar. SX Performance fuel pressure regulator. 3,4 bar fuel pressure. Modified standard fuel tank. Holley Blue pre-pump. 3 litre catch tank in aluminium. Bosch motorsport 044 main fuel pump. Audi K-jetronic main fuel filter. Calibra Turbo watercooler. 75 degrees Irmscher thermostat. Saab 9-5 Aero oil cooler. MBE Systems 970 ECU (fuel & ignition). Distributor removed. Bosch direct ignition coil, double-fire type. NGK BCPR7ES spark plugs. Magnecor custom-made ignition leads (8 mm competition type). Bosch LSM-11 wide band lambda sensor. Lexmaul 4-2-1 & 3" custom built stainless steel exhaust. Aquamist water injection.

Current on-going modfications

Peak & Hold injector controler, own design. Allows the MBE to control low impedance peak/hold injectors (opening current 4A, hold current 1A). The p/h-injectors are way faster to open/close than normal highimpedance injectors and also allows higher fuel pressure without trouble. Installed yesterday and works great!

Lambda change! Bosch LSM-11 "wide" band lambda didn't work as expected. MBE can't handle this "wide" lambda even if they claim they can. The LSM-11 needs to have an ECU that handles the temperature compensation circuit (heater) and MBE can't do this. The LSM-11 heating circuit is just connected to constant 12v... Result? The readings are far-far-away from reliable. I used an Autronic lambda instrument with the LSM-11 when maping the engine, which controls the lambda heater correctly.
Now I've installed an Innovate Motorsports (www.innovatemotorsports.com) wide band lambda logger, with an auxbox (logging of TPS, MAP, EGT etc) and I also got an extra external 52 mm low profile programable display for the dash. This lambda has an analog output that I will connect to the MBE lambda input. With this (reliable) lambda value I finally will be able to use the MBE "lambda target map" during crusing (eg closed loop), wich should save some fuel.

In a few weeks the 89 mm inlet pipe will be rebuilt/moved to free up some space for an camshaft sensor that's needed to run the MBE in sequentinal injection mode. The throttle house will be moved also, and a new shorter gaswire installed (as you can see, the solution right now is not so good looking...).

The air bypass valve will be replaced. I'm using a HKS "Racing" valve right now, but its function is unsure in this kind of application. A vaccum actuator controlled 40 mm throttle will do the job from now on.

New smaller supercharger pulleys waiting for install.

And more...


 
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#12 ·
the mbe can do the lsm11 fine as its not a true wideband, you just need the relevant voltage map for it. i run one fine for idle and midrange fuelling, but its no comparison to a real wideband setup and shouldnt be used to get accurate fuelling changes at the top sites (i know mine doesnt react as quickly as the engine accelerates also)
 
#23 ·
Rob@RSC said:
the mbe can do the lsm11 fine as its not a true wideband, you just need the relevant voltage map for it. i run one fine for idle and midrange fuelling, but its no comparison to a real wideband setup and shouldnt be used to get accurate fuelling changes at the top sites (i know mine doesnt react as quickly as the engine accelerates also)
We used the Autronic exhaust gas analyzer with my LSM-11 when mapping the engine, this Autronic values was diffrent from what the MBE ECU presented.. I trust the Autronic instrument more. :rolleyes:

But that's not a problem today, as a complete wideband lambda kit is cheaper than a LSM-11 lambda alone. ;)
 
#25 ·
Thanks for all of your positive comments. ;)

I left out the power figures as I don't have a clue. I hate to guess without having a dyno paper backing it up.

But what I do know is that a friends engine (copy of my old engine with the ENEM twinscrew charger kit and a MBE 967 ECU) produced 230 bhp at the dyno and later proved 224 bhp in a rolling road test. And that's without an intercooler! Charge pressure = 0,8 bar, +24 degrees celcius outdoor temperature. Charge temperatur ~110 degrees.

My current engine has an bigger supercharger, an intercooler and higher charge pressure.

Let's say 230+ bhp? :D
 
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