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Running a L28ET N/A?


Guest jbbatten21

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Guest jbbatten21

So I went out and bought myself a nice l28et for dirt cheap. I had planned on rebuilding it and taking my time gathering parts and so on. Well it turns out it is in better shape than I expected :D. Now I have this wonderful, useable engine without the money or parts needed to run it fuel injected, much less turbocharged. I currently have the L24 in my 240z and was hoping to just swap out the intake and exhaust onto my new L28, as the L24 has a spun bearing and will be needing some machine work. Anyways, my question is, how can I expect the lower compression engine to perform without boosting? I don't plan on doing anything to the engine, other than my stock SU carbs for the 240, and a cheap rusty 3 into 2 header. Can I pull it off and still have a decent performing engine, or is it gonna be a dog and I need to wait? I miss my Z and want to get it on the road as soon as possible, and the turbo path is going to take some time.

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I would think it has to be better performance just by displacement alone. I would also think you may need to run it a little leaner. But maybe because of the bigger displacement you may not.

 

Either way you will at least have a Z that runs. Spun bearings are not fun.

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Do the intake and exhaust swap. I ran mine for several years with a F54 block and a P90 head using round top SU's and a 3 into 2 header and it felt virtualy the same as the L26 that used to live in there. I doubt if you will notice a differance in power but you will have a running Z again. BTW if you have the P90 head it has the hole cut out in it for the mechanical fuel pump so no mods needed.

 

Dragonfly

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Guest jbbatten21

My biggest concern is the drop in compression. I do plan on getting the engine in this weekend, so we will see how it feels. My L24 had some work done to the E88 head before I bought it. It has oversize valves, nissan competition springs, a mild port and polish, and a pretty lopey cam. Even if the power level of the F54/P90 combo isn't up to par with my old L24, a slower Z is better than no Z I guess, (Well for now at least) Thanks for the responses guys, and I will keep posted on how it performs. BTW my Z is fairly gutted, so it tips the scales at under 2000 lbs. Can't wait for the turbo setup to be complete and running!

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The drop in compression will have such a minimal impact on performance vs if it had the flat tops, you probably wouldn’t even be able to feel the difference set of the pants, from that little bit of compression ratio difference.

 

Bolt on your carbs and exhaust, just run regular unleaded, set the ignition timing a little aggressive, say 40 degrees total mechanical advance, and this low compression 400CC larger engine will pull harder than the L-24 hands down.

 

FWIW, the OE Turbo cams have a wider lobe separation than the N/A cams. If you also install a stock N/A cam, it will give you little more mid range punch that you will feel seat of the pants over the flatter power band that the turbo cam would deliver in your N/A Turbo long block application.

 

Have fun…

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Guest jbbatten21

That would be the ideal (temporary) solution for me, however, the E88 is in poor shape as the oil rail came apart in the head, causing low oil pressure and inadequate oiling to the cam lobes and lash pads. The power issue isn't that big of a deal as I plan on building up my turbo setup throughout the summer and installing it later this summer.

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I figured there was a good reason.. above and beyond the extra work it would take as opposed to installing the complete f54/p90 longblock.

 

Sounds like you're probably going to be in decent shape as it is anyhow. Good luck with the swap.

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granted, mine was running rich, but I had the SUs on an L28ET and it seemed to run out of steam above 4200-4500 rpm. I have since replaced the pistons with domed nissan motorsports pistons, along with a couple other items, but the engine is still out of the car.

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Guest jbbatten21

Well I finished up the swap earlier today, and to my surprise my $125 junkyard engine runs excellent. I haven't gotten a chance to fine tune the carbs or check the timing with a timing light, but it seems to have plenty of power. I have noticed it seems to fall on its face around 5500 rpms, but it is probably from being somewhat out of tune. I don't plan on running it up to 5500 very often, so it doesn't really bother me. Thanks for all of the input.

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Good to hear!!! You've got a runner again!!

 

I too just picked up an '81 turbo motor and plan on installing it in my '71.

 

Just got the long block home yesterday, and no time to work on it yet, but looking forward to cleaning her up a bit and getting her ready to install!

 

Sounds like we will be along the same time frame with our builds, so let's keep in touch this summer and help each other out!

 

good luck,

 

Astrohog

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