differences between L28 and L28et

[pdxvento]

hey guys,

i was wondering if someone could explain the differences between these two motors. as i understand, the L28 comes in 75-78ish 280zs, and the L28et comes in the 79-83ish 280zx turbos? they are both straight 6's, but what is different between them other than the turbo (or lack of)? i understand that the L28et has about 31 more HP than the L28? is this correct?

My application is im trying to figure out what i want to do with the engine in my 280z. ive been told by people on here that putting a turbo on a L28 is a little more than worthless, and that i should just swap in a L28et...if i swapped in a L28et, i would rebuild it first...and if im going to rebuild the L28et or the L28 and put a turbo on it regardless, would they have any real distinctive characteristics?

sorry for the long post. i hope this makes sense...

thanks!

jason

[z_boi]

well, i know that the heads are different. where the l28 has a n42 head with round exhaust ports and the l28et has a p90 head with square exhaust ports. I think that there are more water passages in the l28et, but im not sure.

[pdxvento]

which would you say is better? im guessing the L28et is better equipped for boost? thanks for the reply

[z_boi]

well, how much power do you plan on pushing? if you jus lookin for a little extra power and can salvage all the turbo parts. you can jus turbo the stock l28. but if you wanna boost more and run 250 + hp then your better off doing the turbo swap.

have you tried to using the search on the forum? You can probably find some good info.

[pdxvento]

haha yea, the search on this board and hybridz.org is how ive learned this much . im looking at around 350-400, in a fully built turbo motor. i want to rebuild it, maybe stroke it to a 3.1, put a t3/t4 turbo, JE pistons, etc etc. money isnt really an issue, i was just wondering if i plan on replacing the turbo and internals anyways, would there be a difference between the two engines? thanks

[texasz]

The blocks are different also! The '81-'83 280ZX had an F54 block. I'm not sure that I'd try and put a turbo onto the 280Z engine plus you said that if you were going to do that you'd rebuild any how....just get the 280ZX turbo engine to start and you will probably be better off. Avoid the '83 though, it had a P90a head on it with hydrolic lifters and this head is generally considered junk.

[pdxvento]

thats what i wanted to know! how are they different? just completely different designs that both happen to be 2.8Ls? are the 83 heads swappable with the 80-2s? and i have read about the f54 block being the best, i just was unsure that it was the same as the L28et engine. thanks for your help!

[LEN168]

f54 is best, f the rest.

turbo head best designed

turbo block has low comp pistons-the onlydifference between that and the na from 81-83 is the pistons

heads block swap with any l28

l28et is good beginer turbo engine due to low compression and high quench head setup-tough as nails.

you can turbo any L motor and make sick power

only reason turbo motor is prefered in my case is that I use complete efi setup as well, turbo motor tolerates more.

NA flattop f54 with turbo head brings cr to around 8.8 from 7.4 (stock turbo cr) and with tuning will put the smash down.

engines blow up from detonation, not boost.

I run guts of boost daily, and I love it.

[texasz]

Give ZGarage a read, it should answer many of your questions. I do not want to try and retype it nor do I personally have the experience to due it justice. The only thing I would add is that to get the results from the P90 head he states requires some work (shaving, etc) whereas if you bolt up an N42 head you get the same results with no additional work or expense (N42 on an F54 block with flat-top pistons yields a 10:1 compression ratio) and SU carbs; this is the route I'm working on right now. Here's the link: http://geocities.com/zgarage2001/z.html

After this I'm sure you will come back here with many questions but you will know more too.

[pdxvento]

that answers a lot of the questions i had. thank you very much! i think that will hold me over for now

[LEN168]

ran n42 head on f54 flattop before turbo on my 75

3 angle valve job mild cam, turbo fuel injectors and na guts in turbo afm with some adjusting. 4.11 r200 and 14x6 six spoke wheels with a header and a 2.5 inch exhaust, thing ran SICK...

basically the brian little buildup with efi vs. su carbs, thing was cool to drive thats for dang sure, 7000 rpm shots in every gear, loud chirps whenever I wanted, and 20mpg once I got it on a dyno. Ran 14.4 with that setup, which is exactly what I did my first time out with the turbo motor with stock boost, no intercooler, a few minor bolt ons, big exhaust, and a 3.54 rear gear with the same trans. Difference here being I get 25mpg average on the fwy now with a high of almost 30mpg on long trips averaging 85-90mph, where I got 20mpg on the NA doing the same speeds. If I would have put the NA engine in a 240z high 13s would be possible, and I would run carbs on it and really kick some butt!!! Either way, if its fun thats all that matters to me.

[hls30.com]

The P90A head has advantages and disadvantages. If you keep your foot in it all the time, and are always at high rpm, then the P90 is much easier and economical to rebuild, and is probably a better choice. If you drive on the street, "wind it out" occasionally, and want a quiet engine, the P90A requires no valve adjustment, and is almost completely silent, and has much higher mtbf because of having fewer moving parts. Also they can be had cheeper because most people think they are junk. Think about it, they are the ultimate evolution of the 6 cyl L series head-designed for a car that was designed to be comfortable, quiet, and fast- exactly the same car the P90 was designed for. Don't forget, if the P90 was everything the Datsun Engineers wanted, they would not have replaced it with the P90A so close to the end of the run of the L series engine-whay would they pay for the re-tooling for the manufacture of the P90A if there was no advantage?