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Discussion Starter · #1 ·
I am in the process of building a Bob Legere 2.4L. I plan to use a 2.0 FI system, Megasquirt likely as well. European 2.0L exhaust manifold to 2" exhaust. Head has 2.0L intake and exhaust valves, and is ported preaty well. Low compression pistons (for the supercharger next year). My hang up is the camshaft choice. I would like to use a hydraulic grind for street use. My goal is to be able to scream off the line and accelerate fast, I am not interested in top speed as much. I dont mind a rough idle.
 

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Stock!

Never underestimate the STANDARD Opel hydraulic cam for this application.....
 

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opelwasp said:
I am in the process of building a Bob Legere 2.4L. I plan to use a 2.0 FI system, Megasquirt likely as well. European 2.0L exhaust manifold to 2" exhaust. Head has 2.0L intake and exhaust valves, and is ported preaty well. Low compression pistons (for the supercharger next year). My hang up is the camshaft choice. I would like to use a hydraulic grind for street use. My goal is to be able to scream off the line and accelerate fast, I am not interested in top speed as much. I dont mind a rough idle.

Supercharged engines have different needs than NA engines. I agree with Jim in the sense that a stock hydraulic cam will have the best overall idle quality but at some point it will be the restriction in the system with a supercharger. Also the fact that you're intending to increase the engine size tends to lower the rpms at which the hp peaks and the torque peaks. European 2.4's (with better breathing heads and intakes) have a power peak at 4800 rpms.

If you want to extend the rpms a bit and enhance the supercharger's ability to make power, you have to do a few things different. Now, keep in mind this goes completely against all the normal 'rules' for Opels! You actually want to improve the exhaust flow substantially for a supercharger application. A bigger header or ported Sprint manifold, larger main exhaust pipe than for a NA engine, and a cam with a few degrees more duration than the intake side will help out. The supercharger has no problem cramming more air into the engine, but you need to help it get the burnt gasses back out! You definitely want the cam to have a wide lobe separation angle too, in order to minimize overlap and therefore keep the boost pressure within the cylinder. You really don't want or need a cam with a rough idle, you just want to help the pressurized air into and out of the cylinder.

Bob
 

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Discussion Starter · #4 ·
the supercharger option maynot happen on this engine. if i get to do it, it will get roller rockers and a new cam anyways. at this time my main concern is low-end torque with the fuel injection, and street driveability. should i run split profile or just a combo cam from Gil?
 

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Pretty much any modest cam you stick in there will give you plenty of low rpm torque by virtue of the displacement, the port volumes, and the intake manifold design. No reason to rev it above 5k unless you really cam it up. Case in point was the 2.4 that was dynoed at Carlisle last year. It had a 2.4 head, twin 45 DCOE Webers, 2.5" exhaust and a pretty healthy solid lifter cam, and it made all it's power by 5500 rpms.
 

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Discussion Starter · #7 ·
thanks bob, and others
 

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ConreroGT said:
What was the final HP result on that 2.4?
126 hp at the rear wheels, and I think 150 lb ft. of torque. Very nice street engine, I got to drive the car last fall, and the response of the Webers was excellent. Figure about 154-155 hp at the flywheel, assuming 17-18% driveline losses.

Bob
 
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