L28 Fast Road Engine Rebuild - Advice Wanted! | The Z Club of Great Britain
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L28 Fast Road Engine Rebuild - Advice Wanted!

Discussion in 'S30 (240Z,260Z,280Z) Engine' started by Woody928, Mar 21, 2020.

  1. Woody928

    Woody928
    Z Club Member
    Staff Member Moderator

    Well hello again!

    For those of you who don't know, it looks like I'm stuck back in the UK for the next few months waiting for this global pandemic to resolve itself :banghead:

    Needing something to keep myself busy I'm planning on stripping down the L28 N42 - F54 combo that I have sat in the garage and doing a ground up rebuild ready to drop into my 240z.

    Now I have no experience whatsoever in building an engine but you've got to start somewhere so I really need all the help and advice you can offer. I've read dozens of threads but lots still goes over my head right now.

    I want to build my ideal fast road engine for the car as its the only area now lacking. It won't be the most powerful engine out there but the idea is that the car remains very usable while being more than capable of overtaking when required etc.

    Most importantly I want to set out my goals for the engine:
    • 200bhp at the flywheel (rather slightly over than under)
    • High revving engine, it needs to safely be able to rev to 7k rpm consistently (Not looking for a debate over torque being preferential for a road car, its my preference and driving style)
    • Remain street-able
    • Reliability
    I have no idea how realistic that list is, however I'm hoping its very achievable with much bigger builds already been achieved across the globe.

    Bolt on mods that I already have and intend to use:
    • Ztheraphy Carbs
    • Zstory Racesport Manifold
    • OS Given Lightweight Flywheel (4.7kg)
    • Electronic ignition
    • Cold Air Induction box
    • Mishimoto rad, electric spal fans etc
    Donor engine is a L28 N42 head - F54 block which was healthy and running before removal I'm told .

    What kind of budget do you think I need to be looking at? I'm not looking to spend the earth but appreciate the investment in quality parts for the long run.

    You are all the voices of experience, I'm here to listen, try not to make mistakes and ask lots of questions...
     
    Mikee likes this.
  2. franky

    franky
    Z Club Member

    My stock answer for a package that'll work together well and be a sensible price given exchange rates is to email Mr Mori at Kameari. You'll be into about £1500 of machine work and £2500 of parts at a rough guess?

    Its about getting bits that'll work together well.

    Pistons £900
    Rods £400
    Cam+bits £600
    bearings/bits £250


    I've no experience of SU's, but I would ask if they'd flow enough for 7-8000rpm?

    Glad you made it back without too many hold ups.
     
    Woody928 and Mr.G like this.
  3. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

    If everything is all in good condition to start with (crank, pistons, bores, rods, valves, seats, guides etc) then I'd think at the low end you could do it for about £2k.
    That's a bit of Porting, a cam and a stock bottom end refresh and balancing.

    Head
    Cam £200
    Lash pads £100
    Porting & polishing & fettling £500
    Skim £100
    Shims for cam tower £50

    Bottom end
    Bearings £100
    Rings £100
    Seals & gaskets £100
    Timing kit £100
    Honing & balancing £300
    Crank damper £300

    If there's anything needs repair, or you want nice bits, it goes up from there.

    Oh, and get the "modifying your nissan OHC Engine" book.
     
    Woody928 likes this.
  4. richiep

    richiep
    Z Club Member

    As much as I agree with Jason’s love of all things Kameari, Jon is on the money for the specs you are talking about. You don’t need to go all out on the spends to get 200whp if attention to detail is followed and the right work done. The engine in my red Z is getting in that region with 87mm cast ITM pistons (with small DIY flycuts), L28 rods and crank - albeit balanced, polished etc., stage 3 Schneider cam in a ported, skimmed N42 head (and not a particularly advanced port job either - certainly not compared to what I would do myself nowadays), the Fujitsubo system, etc. It is running 11.3CR though!

    Just go through methodically and prepare things well, replace what needs to be and focus on a nice port job and well prepped bottom end.

    Definitely buy the “modifying ...” book and the “rebuild” sister book.
     
    Woody928, AliK and franky like this.
  5. johnymd

    johnymd
    Z Club Member

    The costs do tend to run away with themselves if your not careful. I agree with all that has been said and I don’t think you need forged pistons and rods. Cast should be fine. With rods I would probably get the maxpeeding ones as they are only £285 and you’ll same on lightening and balancing. Get the biggest bore you can with off the shelf pistons. Spend good money on balancing. Cam and head is where the power comes from. Try to keep below £4K budget if you can.
     
    SacCyclone, Woody928 and AliK like this.
  6. hallie

    hallie
    Z Club Member

    Following.

    I have a L28 and would like to build the same.
     
  7. franky

    franky
    Z Club Member

    I would go for forged pistons though, just for how hes after the engine feeling.
     
  8. AliK

    AliK
    Z Club Member
    Staff Member Moderator

    You see, there goes over £1k by the time it’s taxed and delivered!
     
  9. Pondo

    Pondo
    Z Club Member

    I’ve been thinking the same with my l28 although I could do with a N42 head not an N47. I too am following this.

    Welcome back Woody......shame you had to cut your trip short.
     
    Woody928 likes this.
  10. franky

    franky
    Z Club Member

    Circa £500 extra.........

    Because you're worth it :)
     
  11. johnymd

    johnymd
    Z Club Member

    But why do you consider forged pistons are better for a road car? Surely cast are much more suitable. Especially as it’s not forced induction.
     
    AliK likes this.
  12. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

    I don't think there's a lot between n42 and n47 heads. I think the P heads are the ones to go for if you can find them.
     
    Pondo and SeanDezart like this.
  13. franky

    franky
    Z Club Member

    lack of mass. He wants a higher revving feel from his engine not an engine that feels like a td.
     
  14. atomman

    atomman
    Z Club Member

    I have forged pistons in my engine but probably would have gone with cast if i didn't have a deal on them, most aftermarket pistons use a L24 rod length so you an use the maxspeeding rods which are a good price and you get a better rod ratio, get all the bottom end dynamically balanced , flywheel to front pulley,

    From my experience over the years most of your gains will come from making the engine breath easier , i.e porting, polishing, exhaust, size of valves and cam choice , but compression ratio plays a part to,

    I know you can get power with SU's but they are never gonna breath as well as triple weber's are they ?
     
    AliK and Woody928 like this.
  15. Woody928

    Woody928
    Z Club Member
    Staff Member Moderator

    Thank you for all of the responses chaps! It sounds like the biggest priority is taking time and making good preparation and actually sticking with stock components however focusing primarily on the head.

    I have acquired 'the book' and will start reading and trying to educate myself.

    Where's the best option for parts for these kind of builds, will rock auto be the place to go? assuming no where in the UK has anything?

    I'm going to use them to start with because I already have then so its very budget friendly. Later there's a possibility I may look at OER's or Mikuni's however that's way off...

    Thanks, it was my absolute last resort but looking at the situation now I'm glad to be here...

    Thank you, you total gent :bow: Is there anywhere its really worth spending on the 'nice bits'? Or am I just better off focusing on putting most of the effort into having the head done correctly?

    There looks to be two choices, which ones are you taking about Jon?

    https://www.maxpeedingrods.com/Dats...High-Performance-4340-EN24-H-Beam-Conrod.html

    https://www.maxpeedingrods.com/Niss...High-Performance-4340-EN24-H-Beam-Conrod.html

    Pistons wise, I'm presuming I want to be trying to bore out slightly to increase the displacement to help me out a little bit without going crazy? So in the realms of +2 to make it around 2.9L engine?

    What is the advantage to going forged? I'm all ears and certainly want to future proof the bottom end so that I don't ever need to revisit it again. Ultimately the head would be much easier to change later if I wanted to... (not that I plan to).

    Idiot here, what is the rod ratio and why do the max speeding rods give you a better rod ratio? The balancing work seems to be the most crucial from everything that's been said...

    Any recommendations on off the shelf cams?

    Thanks man, don't worry I'm leaving again as soon as is possible. At this rate I could get very bored for a while though...
     
    AliK likes this.
  16. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

    Maxspeeding rods do L24 and L28 length rods. 133 and 130 respectively I think. The longer the rod, the smaller the angle deviation from straight up it has at the little end, and the smaller the angle the less thrust there is against the bore which means less wear and more power.
    But, there's not a huge difference between 130 and 133.
    Whichever you pick, you need a piston with a pin height to match.

    You can definitely get 200 fwhp out of stock displacement and pistons and rods as long as they're all in good nick.

    If you do swap to maxpeeding rods (or any other decent aftermarket rod I expect) they're full floating pins so you'll need pistons with gudgeon pin retaining clips.
     
    AliK and atomman like this.
  17. ffastffreddie

    ffastffreddie Forum User

    Don't buy rods which give the big end width as XXmm.
    Don't ask me how I know!
    Steve
     
    AliK likes this.
  18. SeanDezart

    SeanDezart
    Z Club Member
    Official Trader

    I can't believe you said that.:D
     
  19. Rob Gaskin

    Rob Gaskin Treasurer Staff Member Moderator

    My advice from my own very limited experience, but my engine gave good power and reliability:

    Save money on components - Nissan quality is good.

    Spend on getting someone who can build engines to do it for you.
     
    Woody928 and AliK like this.
  20. SacCyclone

    SacCyclone
    Z Club Member

    Woody,
    Since so many of us are following this engine build because we want a similar build, would you be so kind as to list out items you eventually purchase?
    That would be a great help.
    If any of the items are ordered from the states and they give you a problem with POST, you can ship them to me and I will forward to you if that helps.
    Mike
     
    toopy, MaximG, atomman and 2 others like this.

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