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l20et rebuild project


drtydog

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hi guys

 

before i start, please don't say chuck it away. i'm not aiming for maximum power out of this build, it's just a low budget rebuild, plus i have 4 complete l20et engines for parts lol this going to be going in a r30 skyline which will be pretty much daily driven

 

the plan is:

 

rebuild block with new rings and bearings, block should just need a light hone hopefully, but will find that out once the engine is opened up

 

most of the work will be in the head.

 

i have an l28e intake manifold off an n42 head. since i won't be useing tis on the l28, i figured i could make use of the bigger runners for more flow on the l20, and port the head to match, clean up round the valves ect. and just try to get it flowing a big better. in your expert opinions, will this work or am i wasting time?

 

i have a reground cam in one of my spare engines, unsure of specs tho as the specs card has gone walkabout.

 

also have a vg30et steel shaft turbo, vg30et injectors, and a 55mm throttle body which should fit the manifold lined up. along with a fmic and a 2.5" exhaust i already have on my other r30

 

is there anything ive missed out or should look at doing while i'm at it?

 

also unsure if i'll need heavier valve springs? what are the factory valve springs capable of?

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The flow is not so much in the diameter of the runner, but the way the air makes the bend to flow through the valve opening. Bowl work pays FAR more benefit than simply using the largest port available.

 

Using the L28 intake may help because it's roughly around 3mm diametrically larger, but that flow difference would need an engine running up far beyond where you would run a cast-piston L20ET normally.

 

Using an Early Dual Carb L20A Camshaft in the L20ET would give you a power delivery curve with a torque peak around 4500 rpm, and a power peak closer to 6300 and which would rev freely like the early 240's Fairlady Z's to around 7K---the practical limit for the cast pistons anyway.

 

It makes for a very nice street turbo setup that way!

 

As for an N/A L20A... You may want to check out this link:

 

 

Is this what you were going for? It's what I went for when building an L20A...

 

So I'm definitely NOT in the 'chuck it' crowd...

 

Sticking a Turbo on THAT one would net some impressive power numbers I posit. We just need to put flat-tops in for a lower compression ratio...and go after G/BGALT records...

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I'm like Tony and I like the L20A ET engine. I have two of them too.

 

Great for revs, short stroke, great rod to stroke ratio and small valves in the head, all permit these engines to rev HARD! :D

 

Porting the head isn't something that's needed for daily street work. Putting on a head with big ports is akin to putting in a big cam. Great top end but off boost, low speed torque just sucks! I'd put in a bigger cam before I'd make the ports bigger IMO. Just don't go stupid in the bigger camshaft department. :wink:

 

This what your head should look like after some basic cleaning up. It's an L20A ET Y70 head.

 

Cheers.

Y70 2L head small file 018_thumb.JPG

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like i said i already have a reground cam, just not entirely shure of the specs untill i find the spec sheet, but been told it helped it rev out way better.

 

the other reason i wanted to use the l28 manifold is it has way less emisions crap on it than the l20 manifold

 

also, it is the 05l head i'm working with. jap spec l20et

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