Help with L28 Build in Aus.

[Fitzpatrick Speed Works]

Hi all,

 

First post long time reader. I have spent the last 3 months using the search function in the L6 section gathering as much information as possible but still have a few questions.

 

I am building an N42 L28, currently the motor is in stock configuration with a N42 head. I want to build the motor to achieve around 200-220rwhp. I can have the compression at around 11:1 or even 11.5:1 as where I live in Australia 96 RON fuel is easily obtainable at a reasonable price and the car I am building it for will only see 500-600 miles a year if its lucky.

 

My main question is in relation to the head I go with. I have a E-30 head here also. I am wondering to achieve that kind of comp with a L28 rod, L28 87mm flat top I may need to close the chamber on the N42 or will a .80 thou shave achieve what I am after? Obviously for the kind of power I am after I am willing to spend the money and time on the head, would it be more worth while to put the N42 valve train into the E30 head. Will I be able to port the E30 big enough as I know the ports are quite small??

 

Sorry for all the questions but having used the search I have found many conflicting points of view. Is there any way to achieve a close to 0 deck height with ka24 pistons. I can use a l24 rod out of a l24 I have but my understanding is that the piston will still be down the bore and obviously with that I wont achieve the comp I am looking for. I saw a post buy a gent here saying that he used Ka24E pistons that where shaved flat and valve reliefs put in, the post seemed to suggest that his deck height was basically 0. Is that actually achievable, is there differences between ka pistons, which one should I be looking for, as a 89mm bore would be appealing to me, and work better over the L28 1mm over piston as this will also help with my comp aspirations or am I off the money here?

 

 

Thanks for all the wisdom, I have all the L series books and read alot of literature on the subject but the people on this site have by far taught me the most.

 

Regards,

Daniel

[Daeron]

The simplest route is to get custom pistons made to match L24, 133 mm rods. I forget where the link is, but i *think* a company stateside like Jeg's has a deal to get a set of Ross Forged pistons on the CHEAP, something like 4-500 USD. The secret is just order pistons with the specs you need, and don't tell them it is for this engine or that engine.

 

This would also allow you to bore out to 89mm if you would like, to get up to just over 2.9 liters.

 

 

The way I have come to look at it, the pistons and the camshaft are probably the two most important internal engine parts to swap out to aftermarket on a custom L-series build, when serious power is desired. Rods are good (to a point) crank is good (to a point) but the camshaft is a no-brainer.. and in my mind, so are pistons. Get custom pistons cut SPECIFICALLY to what you want. Between the pistons, the cylinder head selection, and the camshaft, you have your engine. Block selection, crank selection, rod selection.. thos are all easy, all stock parts can be used, and all are essentially a matter of either taste, or what you REALLY want out of the motor.

 

I keep playing with the idea of trying to get one of you Ozzies to ship me an L20A crank to build a DE-stroked L6... I just have to convince myself that I really don't mind poor low end power on a streetcar that could run up to 8000 RPM...

 

BUT, thats just an option. The cam and the pistons that go into the motor, really should be determined by the rest of your "options" combined with your goals.

[ozconnection]

I keep playing with the idea of trying to get one of you Ozzies to ship me an L20A crank to build a DE-stroked L6... I just have to convince myself that I really don't mind poor low end power on a streetcar that could run up to 8000 RPM...

 

You want, I have. PM me.

[MAG86]

I have x 2 L20aET cranks here... infact a whole L20et!

 

In relation to the 1st post, the E-30 you have is most likely off a 240k with a carby setup L24. They usually have the injector holes cut in too.

They dont really flow much at all compared to the N42 on your L28

I would use the N42 over the E30 anyday....

A good cleanup of the ports, and polish the exhaust valves and bob's ya uncle

Also if you need some expert aussie advice,

Stewart Wilkins Motorsport

6/16 Wingate Rd

Mulgrave

Sydney

New South Wales

Australia

2756

Phone: 02 45772400

http://www.swmotorsport.com/

[Fitzpatrick Speed Works]

Ok so I am to stick with the N42 head, how do I acieve my comp in the best possible way? Shave or weld?

 

Can someone tell me the specs that I need to supply to get the pistons made, has anyone here ordered them what are the pin heights, cc, deck height etc??

 

Thanks for the advice so far, appreciate the imput!

[SLVRBLLT40]

I just built myself an L28 N42 for my 240. I'm using the stock '83 280 rods and pistons (which pop up above the deck .020). I found out too late the head was chopped .030 and with a stock headgasket, it ended up yielding me about 11.6:1 compression. Obviously check your specific head and don't take my word for it on any modification. There are some pretty spiffy compression calculators out there to help ya out.

[ozconnection]

I have been down this path myself. Stewart Wilkins will recommend you use an E88 from the L24E R30 Skyline. A 'closed chamber' head, you will have more chance at achieving your high compression ratios using this head milled a 'little' bit and the chamber shape is better suited for high comp, being more detonation resistant than the N42. Needs L28 inlet valves though 'cause the E88 uses 42 mm valves, not the L28 44's.

 

There are different headgasket thicknesses that can be used to adjust comp. ratios as well. A compression calculator is a good idea from this point onwards.

 

Are you running carbs or programmable injection? That's still a high comp ratio for Optimax or Shell Ultra, which is 98 octane, I think. Dunno mate, I would drop the comp a little to move away from potential disaster. Nothing worse than a high comp. engine backed down so far in the ignition, it just kills power. Rather, go for a slightly lower comp, 10-10.5 and use the full 32-36 total advance. Good power is made with full ignition advance, not the other way around.

 

Cheers mate.

[Fitzpatrick Speed Works]

I wont be running on opti_crap, this car will run BP 100 racing fuel, which in aus terms is 100 octane, and about 96-98 in American terms, do you think I will need to still back down the comp???

 

I have used the engine calculator flat out but I am new to L series, if I was building a RB I would be set I have built over 30 Rb's, The motor will run tripple 48mm's, they are pretty big but as I already have the carby's lined up and at a good deal this is what I will be using.

 

How easy are E_88 to get and what dollars do they command, I have read here there are 4 types of E88 and 2 of them are rubbish. I can weld the head myself are you sure the e88 is the way to go?

 

Thanks for your advice Ozconnection appreciate the

[MAG86]

The gun E88 head is off a series 1 1981 to late 1983 MR30 skyline, they come in a sedan and a hatch.

They are very similar to the USA Maxima...

The series 2 MR30 skyline has a N47, which is ok for some things but not good for mass power (it has steel pipes welded in the exh. outlets that glow red & burn the unused fuel etc... they also increase low rpm gas velocity exiting the head... so im told!)

The E88 is better for mass power than the N47

the heads usually go for $50 to $100 at the wreckers, but need rebuilding etc.

You can pickup a whole MR30 skyline for $300 to $900, strip the goodies, sell the wheels of, then get it towed and $200 cash in hand from the scrap mental yard... ! know as i have done this a few times before!

 

In VIC I have a few engines here & there... I have actually bought a series 1 MR30 for $50.... just havnt picked it up as theres no where to store it.

 

I will be coming up th the ACT for Duntroon selection in Sept, so I can bring something up for ya if I can get it.

[Nizm0Zed]

well, hello from another Canberra Zed driver.

 

have you looked on the ozdat engine design website?

http://www.ozdat.com/ozdatonline/enginedesign/

 

play around on there if you havent allready.

 

have a look at the setup of the L28 block with flat top pistons, the N42 head, and a 0.6mm headgasket (Nismo metal gasket)

[Fitzpatrick Speed Works]

I have used that engine design thing flat out, but it still doesnt answer my questions about ka24 pistons, or whether the n42 is my best option and how I go about achieving my compression goals??

 

Any other help out there, Jm, 1fastz???

[ozconnection]

What else do you need to know?

 

Why don't you speak to Stewart Wilkins? He has a vast knowledge base and you can pick his brains about your project if you're still unsure of the details. He has supported teams that have competed in the East African Safari with great success and I have personally seen some of his L24's and L28's that he had shipped over to Africa for competition.

 

Personally, you're not shooting for the sky as far as power expectations are concerned. Therefore, you should be able to achieve this much power without extremes in any one area of your build up. Many people have done what you're trying to do and got as good or better power figures using many of the original engine components. Like I have aready said, if you're going to spend some cash, talk to Stuart and spend it there. You could do a lot worse than him.