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250 Crossflow build

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On Tuesday, April 09, 2019 at 7:32 PM, gerg said:

I'm struggling to understand why anyone would make an already undersquare engine even more so. Maybe more off-boost torque? Crank harmonics would also get worse with smaller journals and less overlap. Hardly worth the trouble if you ask me.

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Faster spooling and because you can. I wouldn't do it, but it is nice that people do try these things. Your points about the effect it will have on the crank are correct and are a turn off for sure.

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23 hours ago, gerg said:

I'm struggling to understand why anyone would make an already undersquare engine even more so. Maybe more off-boost torque? Crank harmonics would also get worse with smaller journals and less overlap. Hardly worth the trouble if you ask me.

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Yep. Just need to improve the efficiency of the head and wind up the boost. But hey, each to their own!!!!

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I wish there were more 221 cranks around. That would make for a nice square engine. Ford Argentina made them for much longer and were the basis for lots of 6 full race engines.

Here, they were rare to start with (only XW had them) and a lot would have gone to scrap. The rest went into red motor 236 strokers with the Holden flywheel flange welded to the cut-off Ford rear journal. But Fords are shit remember?

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Over the last year or so I've read up on the last ten years of info, opinions and lessons passed on by crossflow veterans but i still have to ask: If building for a mild streetable turbo, does it still require looking into non ford parts to finish off with something reliable and not spit a pushrod or something silly?

 

I'm on this journey too, but the option/need for a forged assembly isn't going to happen. Having turbo manifolds ready and keeping the stock bottom end, is it dreaming to think I can do an efi conversion and get some head work done to achieve a stout low boost 250?

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Your crossy makes around 150 HP stock, so a target of 200-250 on about 10 psi is what a stock bottom end is more than adequate to handle. Mild boost won't kill conrods, rpm and/or big boost does. Rpm rips them apart, big boost bends them.

Your stock valvetrain will suffice, provided you keep the cam specs mild. That means a working limit of 0.500" lift. Upgraded valvesprings will be the exception.

The key to making boost on standard compression is fuel and ignition management. This is where investing in a good aftermarket system will pay off. Sure there are people who've managed to use OEM computers, etc. but it will always be a compromise. Infinite tuneability will overcome any design shortcomings when adding boost.

On a crossy, the EFI manifold is not ideal for turbo applications, for a few reasons:

The middle 2 cylinders get first shot at the airflow.

The throttle body draws air from the hot side of the engine.

If using a right-to-left intercooler, the air outlet is on the opposite side of the engine to where the throttle is pointing.

And lastly, the manifold itself may become a performance restriction at a certain power level.

So it's best to seek an alternative, and the most cost-effective and simple one is by using an EA-ED log manifold adapted to the crossy inlet flange. It puts the throttle to the front and down, simplifying the installation and minimising turbo piping and keeping everything away from heat.

I can't make any suggestions for your turbo selection as that's not my area of expertise. Exhaust manifold can be a simple log type made from cast bends. No need to go all out with tuned runners on a mild setup. KISS principle wins here

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Cheers for the feedback. I reckon there's a few late comers here who all want roughly the same thing as I do, keep the 250's alive on the road with a refresh to impress.

 

But accepting a warm motor rebuilt by who knows prior, when means figuring out what has been played with. I guess my start will be checking the cam and compression before i do anything drastic.

 

For ignition I've got an MSD 6AL2 prog & a HVC2 coil for spark to begin. But I haven't figured out fuel management ECU options yet, still in newbie learning space. Suggestions welcome?

 

For the inlet manifold, I reckon I'm on point for that but if you could review it would be appreciated?. I've seen a few of these searching the net and noted the ED manifold advice on this forum before, but good pictures are hard to find. It would be nice to see if anyone here has this EFI setup installed with some quality photos? Here's what I've got for intake side, cleaned up for viewing

https://imgur.com/a/k1ROlsH

 

Cheers

BB

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Yeah that's the ticket, exactly what I was describing. Just with the injector sandwich part and the adaptor plate, you'll have to watch shock tower clearance. Other than that, looks the goods mate

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stock valve springs, retainers/locks & push rods are best to upgrade, don't handle higher rpm well or any decent cam,

Member n00bus m@x1mus has a XF ute or ZL xflow running off E series log & EL ECU from memory. I think there's a build thread

in SM Carnage with the AU turbo, they where saying if 6cyl engine can run a 36-1 crank angle sensor & wheel, can adapt a Barra ECU to run it, could then workout some coil packs for ignition, No MSD needed & ECU will run both. check out there video for more info

also check out SLYDOG SLY250 build, runs a megasquirt MS3 ecu with coil packs,

If for lower power a GT3576 from a FG turbo or GT3582 from BA/BF should be a about right, (used may need reco)

all these turbo cars, keeps me think about playing with boost, Hmmm

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