drtydog Posted April 30, 2008 Share Posted April 30, 2008 ok, so been searching through the vast multitude of posts on this site, and it's pretty much left me with more questions than i started with :S and since there's nothing like having your own questions answered personally, i'm going to aska few, please don;t flame me 2 much ok, so i have an hr30 skyline which has an l20et under the hood (05l head, not sure on block) in my bedroom i have a complete l28 of the n42 variation minus 1 rod :S the goal is l28et pumping out 300rwhp from what i understand, compression ration on the l28 is around 8.5:1 am i correct? this would be a fairly ideal compression ratio for turbo? will there be any advantage going for aftermarket forged pistons and rods, considering my power goals, and the cost involved of either importing some or getting somthing made locally? (there are practically no aftermarket parts for L series engines in nz) now the l28 has a bent rod, are the l20et rods the same? stronger? weaker? from reading the forums, seems getting the bottom end balanced is the way to go. i was considering knife edging the crank, but again, with my power goals in mind the the cost involved, is it worth it? now the head. i have the l20et head, which has 05l stamped on it, and i have the n42 head. which is gonna be the better base to start from, and will the l20et head even go onto the l28? porting...again, is it worth it for the cost involved? cam, whats the ideal cam grind for an l28et? (really want a lumpy idle but prob not idea with turbo setup?) not gonna sak questions on the bolt ons side of things till i've sorted out the engine build. the engine will be built with all new bearings, rings seals ect. cheers guys for all your knowledgeable advice, this is one great forum keep it up Quote Link to comment Share on other sites More sharing options...
ben280zx Posted May 1, 2008 Share Posted May 1, 2008 Are you planning to combine the two engine to make one? Quote Link to comment Share on other sites More sharing options...
Challenger Posted May 1, 2008 Share Posted May 1, 2008 From what I know, porting is kind of a waste of money if your doing a budget build. You can gain alot more power by investing what you would have paid for porting in your IC, turbo, or EFI. From some of the stickies it seems like the cam will be fine up to the power goal you mentioned, but I cant give any exact numbers if your wanting to go aftermarket. By itself the n42 with dish pistons and a turbo will be a little high on compression. Im not sure what is best, cheapest, but you might consider getting a p90, or even lower compression pistons? All this is from what Ive read/researched and will be considering it in my build, so as Reading Rainbow said, "But dont take my word for it." Id go read and search some more. Quote Link to comment Share on other sites More sharing options...
violacleff Posted May 2, 2008 Share Posted May 2, 2008 8.5:1 is not the stock compression for an l28et. Its is quite lower actually. I can't remember exact compression but search it out you'll find it. Quote Link to comment Share on other sites More sharing options...
sticky280zx Posted May 2, 2008 Share Posted May 2, 2008 im almost positive its 7-3-1 ratio and im thinking i found that on zdriver.com.....they have an engine,tranny,rear end ratio, and a bunch of other info in a sticky on there..check it out Quote Link to comment Share on other sites More sharing options...
Gollum Posted May 2, 2008 Share Posted May 2, 2008 On the L Engine program the stock turbo compression comes out to 7.38:1, And I've normally seen it rated at 7.4:1. But there's lots of guys that have run turbo parts on NA motors, and get pretty impressive numbers. Stock NA compression is 8.52:1 on the P79 engines, and 8.29:1 on the N47 heads (note that the N47 motors use a dish piston like the turbo, if using a flat top compression it is 9.82:1) I don't know much about the rod quesion. Something in me wants to say they're different, but I don't know either way. I think you can skate by without forged pistons, as long as you tune it really well. 400hp is about the range that the stock pistons will just plain explode once you start reaching knock levels. So keep in mind you'll want to make sure you've got a good EFI setup to tune it, and I'd consider some type of spark control like EDIS. Quote Link to comment Share on other sites More sharing options...
stagefumer11 Posted May 4, 2008 Share Posted May 4, 2008 As you already know ive done this build up, Still doing it. I have a spare motor for my l31 build which im happy to part with the pistons and rods if need be. Also got another set of n/a pistons. (l28e gear im talking about) If you need a spare rod or a set pm me. And we can work something out. When it comes to putting the l28 into the hr30. You need to modifie the oil pick up, There is another boss towards the front of the block for the MAXIMA setup and the south african r30's, This needs to be drilled out and threaded, then you move the oil pick up to there. Block the old one off. Install the l20et sump and your running. Quote Link to comment Share on other sites More sharing options...
drtydog Posted May 5, 2008 Author Share Posted May 5, 2008 hey, i'll b in touch about the rods. do you have any pictures of what you've done with the oil pickup? I think you can skate by without forged pistons, as long as you tune it really well. 400hp is about the range that the stock pistons will just plain explode once you start reaching knock levels. So keep in mind you'll want to make sure you've got a good EFI setup to tune it, and I'd consider some type of spark control like EDIS.yes i will be going for an aftermarket engine management system, probably a link or microtech, but havn;t done my research in that area yet 8.5:1 is not the stock compression for an l28et. Its is quite lower actually. I can't remember exact compression but search it out you'll find it. this isn't a factory turbo engine, as i don;t believe nz got the l28et. this engine is a non turbo n42 (yes with dished pistons) Quote Link to comment Share on other sites More sharing options...
stagefumer11 Posted May 5, 2008 Share Posted May 5, 2008 Sorry, didnt take pics of the bottom end mods. Its simple when you have a look yourself. Quote Link to comment Share on other sites More sharing options...
Daeron Posted May 6, 2008 Share Posted May 6, 2008 First off, the l20 rods are different. Secondly, the N42 L28 had about 8.2-8.5 compression. Third, I want the crankshaft out of your L20 (but don't have $$ to buy/ship it, I'm just idly dropping a comment on that one) If you have an L28 that you are going to be using as a base for a turbo build, then you've got a number of options. The cheapest route would be to go with re-using your pistons and rods, keeping the boost numbers moderate, and never running it with anything less than megasquirt as a controller. The tuneability of the ECU combined with moderate boost numbers, and ample fuel, should keep you safe. Most turbo motors built for longevity are lower compression; one route to go to achieve this would be to get a set of factory dished turbo pistons.. but even then (since you are not using the factory turbo HEAD) you are not quite landing at "factory turbo motor specs." Another option is to order a set of custom pistons to lower your compression slightly, and also possibly use L24 rods, and order the pistons with an appropriate pin height. As I just read jmortensen mention on another thread, this also gives you a slightly better rod/stroke ratio. The cheapest way to achieve your goal, by FAR, would be to find a complete running 280ZXTurbo motor, even though you DO already have the one L28. Your options are many, and they are only limited by your budget. I just posted in this thread links to three books that are invaluable resources in building an L-series motor, linked in order of importance. Good luck with your build, and if you feel like chucking that crankshaft halfway around the globe for a song, let me know. I'll start warming up my voicebox. Quote Link to comment Share on other sites More sharing options...
stagefumer11 Posted May 6, 2008 Share Posted May 6, 2008 ive got two spare l20et cranks. (two near complete motors) DOnt know on shipping tho. I was meant to get a price for another hybridz memeber to send one over. but been to tied up. Quote Link to comment Share on other sites More sharing options...
drtydog Posted May 6, 2008 Author Share Posted May 6, 2008 as i mentioned earlier,i'm pretty sure nz never got the l28et, or if it did in really low numbers,as it was i had 2 spend months searching for a l28 that didn;t cost the earth and wasn't at the other side of the country lol just out of curiosity, what would you do with an l20et crank? Quote Link to comment Share on other sites More sharing options...
Daeron Posted May 6, 2008 Share Posted May 6, 2008 I have my ideas that might work surprisingly well, with a short stroke and a big bore. Shhh. Regarding the 280ZX motor.. Oops.. Well, I just mentioned that it would be the cheapest way, i was brain farting on even mentioning it as an option. Whatever you wind up doing is going to be a customized job, and its up to you how close you want to match factory specs, and how you want to put it all together. Its just like Legos!!! Quote Link to comment Share on other sites More sharing options...
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