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2.5 petrol rebuild and conversion to EFI thread?


Gazzar

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Yes. I'm going with it. Most of the brands are in the same price range. Landrover is, as usual, 6 times the price.

And probably the same part....

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On 2/19/2020 at 11:29 PM, lo-fi said:

Be careful. Intake requirements for diesel and petrol are quiet different. Short intake runners will rob you of many low end torques, smoothness, efficiency and ponies. 

Plugging numbers in here highlights that you want looong runners. You're not trying to build a high rpm race engine. I've seen first hand what happens when this is ignored - funnily enough on a carb > efi converted engine. Guy built himself a very clever manifold that sat right in the valley all nice and neat with multi point injection. Intake runners of about 1.5". It ran like utter garbage. Popped, farted and backfired off idle no matter what the settings, gutless through mid range, disappointing even screaming, guzzled fuel. 70bhp (flywheel) from a freshly rebuilt 2.8 litre engine with a brand new Kent cam. Swap to an original carb manifold with single point throttle body injection and she woke up. Different engine. Smooth, torquey, powerful. 

Have a play with the calc, it'll show you the way to a good result :) Something similar to that diesel manifold might kinda work, but it'll be a long way from optimal. 

Stuck.

No idea the duration of a standard cam.

 

Help?

Screenshot_2020-03-05-19-47-32-827_com.brave.browser.thumb.jpg.cf0d9b6a4ab20527fd235936596c7a27.jpg

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Where is the runner length calculated from?

And is my sums right?

11 before top dead centre

=11

Top to bottom

=90

47 after bottom dead centre

Total = 148?

 

Screenshot_2020-03-05-20-03-35-768_com.brave.browser.jpg

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14 hours ago, Gazzar said:

How do SPI systems work? Are they injecting constantly?

No, it'll be pulsed just 4x more often - you don't need to time the fuel squirts to coincide with anything, after all carbs are just a continuously leaky bucket. It's sometimes advantageous to fire fuel at the back of a closed valve as it atomises the fuel and cools the valve.

You can also prat around with the settings in MS to do more smaller squirts per cycle which can smooth out fluctuations in the fuel rail... but that's waaaaay over what's worth worrying about in an old Land Rover.

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14 hours ago, Gazzar said:

It's still nearly a foot and a half!?!?!

Ummmm. 

Single point injection with a carb manifold.

Multi point is OUT.

I think you are getting a little hung up on these numbers to be honest!

Point me at one non-sports/supercar engine that has runners that are more than a foot long, and I will think it worthwhile.

You can of course run a plenum, and then runner length is not so important.... But whatever, anything you can cobble together craft together carefully will fit as long as they aren't ridiculously short.

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1 hour ago, Bowie69 said:

I think you are getting a little hung up on these numbers to be honest!

You can of course run a plenum, and then runner length is not so important.... But whatever, anything you can cobble together craft together carefully will fit as long as they aren't ridiculously short.

Indeed...

LR_NEQ_F1.jpg

 

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Thanks, learning as I go...

Plenum. I know nothing about plenumi, or plenums.

Thanks, still good with SPI stuck on a series manifold.

 

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1 hour ago, FridgeFreezer said:

No, it'll be pulsed just 4x more often - you don't need to time the fuel squirts to coincide with anything, after all carbs are just a continuously leaky bucket. It's sometimes advantageous to fire fuel at the back of a closed valve as it atomises the fuel and cools the valve.

You can also prat around with the settings in MS to do more smaller squirts per cycle which can smooth out fluctuations in the fuel rail... but that's waaaaay over what's worth worrying about in an old Land Rover.

That's really useful, thanks. I presume the injector can cope with the workload.

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