xeeclipse

But isn't the bbm manifold vacuum operated? Btw the plenum size isn't any bigger, neither are the runners so I doubt it can liberate much more power. Why would you go pulling these shiters apart in wrecking yards EA-AU when the only real difference is comp ratio? The rest is superfluous IMO.

I'd run an EB-ED 4L...Broadband manifold and stuff sounds tempting but if you are considering a cam I rather not.

425 is overkill man..... 225 is plenty and if you do put a cam in it will meter the LPG better.

If the others are stock the rockers must be shimmed pretty heavily, if not your lifter preload is up to shit. My rods are at 9.580 or somthing like that, just order a chev 5/16 pushrod from a speed shop.

WTF would you pay for a second hand set of pushrods? 351c pushrods have the same thin construction as a 250, why make it stronger when your running the same type of cam and spring rates? Get some chevy pushrods that are .080" shorter like myself and be done with it man.

As long as you don't wreck them in the process......My pet hate is seeing all these grouches at pick a part wreck perfectly good componentry. Some c$%k sucker pulled a T5 out the other day just to take the input shaft!

Truth is their all shit compared to the Barra and coyote, our only saving grace is that the X series falcon's weigh next to nothing and only require a decent amount of torque to get moving. Everyone has their own phylosophy on how they want to go fast, some are conservative while others push the boundaries. As long as your happy that's all that matters.

Geeez...... lighten up and relax with the Jihad XCSEDAN. Fact number 66....... XC falcon's are for cruising and not racing.

This is coming from the guy who had the rattliest 4L in the land ....There's video proof If used within their production limitations the crossflow without doubt would be the more reliable....period.

Btw I'd be using an AU E-Gas motor for this project hooked up to a T5

No shitty guides or tensioner for the chain to flap against. Unless you over rev the 250 past 4,500rpm it's as reliable as a boat anchor.

Crossflow will always be a stronger motor then the 4L. What are you going to do about the ignition curve? Can you put a mechanical dizzy out of an XE into a later 4L engine? Second hand engine or a freshened second hand motor?

port and polish does jack all in the overall scheme of things..... Not even going to bother on my 408w because i know its gonna have more then me or the driveline can handle.

The crossflow head has got a pretty uniform cross section and makes a pretty direct shot at the cylinder. All valid points but a crossflow wasn't built to rev over 5,000rpm. I'm not here to start an argument but lets face it guys, the alloy crossflow head is alot more performance orientated then the rest of the motor will ever be.

1. piss performance EFI cam off, if it doesn't sound gassy and doesn't have a deep resonance...its too small! 2. Forget about porting it, Only makes a real difference in an engine with poor port design. Crossflow is quite efficient and big.

A cam between 205-210 degrees duration is tailor made for a crossy IMO. Makes power from 2,000rpm and falls off a cliff at 4,200rpm. Kind to standard rocker gear, quiet valvetrain operation and smooth running.

Bugger the holley....LPG all the way, these things drink fuel like a fish

Lol....man you have difficulty starting it because your cylinder pressures are peaking before the piston has a chance to reach TDC. putting extractors, holley, msd on a stock cammed engine is pointless. These engines have the capacity and good breathing heads, just put a cam in it and be done with it Then you'll see what real power is. My wagon weighs 200kg over a stocker and is still quicker down the quarter. A cam and good tune will wash 2 seconds off your quarter mile time. I reckon a mild well built crossy can take it up to a 4L OHC engine no problems and heaps easier to modify and work on.

A cam over 210 degrees isn't advisable cause you bleed off too much cylinder pressure in the low rpm range and you'll lose economy. It will also be more forgiving to the standard steel rockers which are best kept under '500 thou lift

I know jack shit about crossflows but from my experience this is my verdict..... flat top pistons preferable but standard 20cc ok shaved HF5-C2 head 210 single pattern cam EFI manifold extractors + 2/1/4 exhaust LPG IMPCO SYSTEM T5 manual 3.27 diff gears 14 degrees initial timing, Holley vacuum secondary springs for converter/mixer assembly This setup may look lame but i can guarantee it would do a dead 15 in and XE-XF

Btw crossflows should have been spun off a WINDSOR, would have avoided some of these retarded valvetrain problems we have.....

Love the simplicity of these engines....... Anyone been to jolly's in dandenong lately? I pulled out a ripper of an engine out of the rusted out panel van in the front row

Sounds like your cam timing is mucked up. You shouldn't be too far off tdc on the balancer with both valves shut

I put a couple of slots into the tube that the LPG valve bottoms out on. It's a vacuum operated 225 mixer like used on every ecotec V6 commodore. No fancy commander units here

Down to 18L around town and 15 on the highway .....Wish someone with LPG knowledge could have taught me earlier cause it has been an ordeal to say the least.... Secret? If using a low vacuum cam on an impco 225 or 200 mixer the only way to meter the idle mixture is by putting slots into the LPG valve supply tube. I initially collapsed the LPG valve spring which just made the gas piss out at an alarming rate. Funnily enough using 10 Litres more per 100km didn't rob the engine of power....got to love LPG