Ok, so i need some help. 260Z engine build

[WogsRus]

Ok so now that i have body under control, time to turn my attention to the engine.

 

I want to keep my L26, why, because this will be a sunday driver, not my toy.

 

I want to do the following.

 

L26 block, mine is a 75 not sure on block stamp. I have an E88 head which i will keep but shave a little to bump up the compression.

 

Bigger valves and a mild port and polish job on the head will be the order of the day.

 

A mild cam is what i am after, not sure about the extent of mild, just something better then stock.

 

Tripple Delotos or webbers 40's to deal with the fuel, decent exhaust manifold and electronic ignition to deal with the spark.

 

So that i what i think i will build, i am after 200hp at the wheels.

 

HOWEVER, i want a CR of about 10.5:1 or so, but i don't want to run a different head. If i run 240Z flat top pistons, i should be able to get about 10.2:1 i think. So i guess if i shave 0.5mm of the head and use a adjustable timing gear to deal with the chain timing i should be ok.

 

 

I have read a few posts about rebuilds, but i was wondering what people have been doing in the past.

 

Can someone tell me what a combo as above would make in HP, only revving to 7500 as i will be using stock rods and standards non forged pistons.

 

 

ANY advice would be greatly appreciated please.

 

TA

 

 

 

 

 

 

[PZG302]

Depending on who's dyno you use 200rwhp will be being optimistic. My motors only see around 140-160 rwhp, but I build them for plenty of torque and don't need to rev them past 7200. This is in my circuit racer.

 

For a road motor you want something that is tractable form down low and works well from about 2500-6500.

 

Personally, I would opt for a N42 head with a little bit of work to the ports, just clean them up, and from talking to different people and how I have set my ports up for injection, don't polish them, the rough surface will help the fuel stay atomised with the turbulence introduced in the air flow.

 

The carbies sound on the money, but don't dismiss injection, the standard L28 injection can work quite welland there are a few tricks you can play to get the computer to work really well.

 

Decent extractors, if you can afford it some custom built ones, that send the gas out through a 2 1/2 inch system.

 

As for cam, for something that's a bit of fun a 65-25 grind will give you good torque, but a 72 degree cam will give a little more top end without being a pig on the road.

 

The revs you are aiming for a little high for mine, my race motor develops max power at about 6800, with a broad torque curve from 3500. You only need to rev an L series to around 6500 for the street too much higher build costs go up to keep it all together, having said that the standard bottom end doesn't need to be touched as Nissan had pretty good tolerances at the factory, nothing like the eqyivalent red motor and old 250 from Fraud in the 70's.

 

Realistically a good road motor that doesn't cost a fortune will put out a realistic 120-140 rwhp, but a good dyno operator will get you 200 if you really want, and maybe a bit more

[Scoota G]

I just rebuilt my 2.6, this my combination.

Triple 45mm Dellortos

N42 head (with a little work)

 

Mild crow camshaft

http://www.crowcams.com.au/search.aspx?EG=58&MK=24&PC=1

 

Genie extractors (which had a really poor fit and needed 12 hrs work)

280ZX Electronic ignition

Hypertec pistons and Hastings Chrome Moly rings (40 Thou oversize)

Full balance and hot tank, resized rods and crank modification.

 

Yep i would suggest the N42 head as it has the larger valves but with compression you'll find a large amount of discussion on the validity of increasing the ratio and that it will only give a small increase for the dollars spent. You may be better spending that money elsewhere (even on a decent dyno tune).

 

I suppose the only problem is how worn the block is in regards to fitting specific pistons mine had to go out 1mm as it was that worn, but the engine machinist also did a sonic test on the block to see if it would go out far enough to accept 2.8 pistons... it was not advisable. At some stage in the future i'll try to find a set of flat top 40 thou over 2.6 pistons just so i can see the difference for myself, but i won't put up too much info as i'm sure you'll get a lot of good advice here.

 

Good luck with your rebuild.

[WogsRus]

Thanks guys.

 

Machining is no problem, my mate who does all our engines has a fully stock workshop, including milling machines, presses and lathes.

 

We managed to squize 100hp/l for our targa car, a 69 hillman hunter royal.

 

Thanks guys for the advice, much appreciated i will read properly once the kids are in bed.

 

TA

[modular9]

all good advice. My 2 cents would be be...

 

Check the water jacket and access holes around the 5th cylinder very very carefully. Weak point and yes I had to blow 2 head gaskets to find that out. This is a common problem apparently on the l series. Hybridz got a big post on it. Fixed it now.

 

L28 + N42 head + L24 grind cam + triple dellortos + ebay extractors + elec dis made 140 rwhp. But I built mine for torque steep curveys. After all usable power is better than non usable horsepower.

 

[Ben]

200rwhp from a modified L26 is well into 'race-spec' build complexity. I would suggest that you don't shave the head for more compression - get pistons with a taller crown height.

 

By changing the head height, you change the geometry of all the valve-train, requiring plenty of time to set it all right again.

 

FWIW, my L28ET at ~10psi (stock internals) pushes about 200rwhp via the 3-speed auto, and that enough for just under 6s in the 0-100.

 

The bottom end won't need strengthening to make your target, but I suggest you check the reciprocating assemblies for balance. I found several grams difference between just the rods in my L24.

[modular9]

I re-read the OP's post and he says he wants it to rev to 7500 rpm. I have basically what he is doing but with balancing and lightening, with the l28 f54/n42 setup. The most I have ever revved it is to 5500 rpm. Where upon I grabbed the next gear.

 

My question. Could the OP's setup ( and by proxy my current setup ) make 7500 before dying ?

[WogsRus]

Well currently the stock setup reves to 7000 rpm, not sure why but it does.

 

I was goign to do mild crank lightening but custom nice and light rods and pistons.

 

We will see where we go, eaven if the engine makes 200+ HP at the fly i will be happy for a sunday driver. Instead of more power i will run a 4.2 or a 4.4 diff and use the gears instead.

 

Ta

[260Coupe]

As the other have suggested 200 RWHP (152rw kw) is very optomistic for an L26 that is still streetable.

Shaving heads is fraught with danger, risking detonation at high rpm etc ...just go 240z flat tops and you will have plenty enough mumbo for road use

 

Take a look at my rebuild, this resulted in around 125 rwkw / 165 rwhp and is very tractable and nice to drive .

http://www.viczcar.com/forum/index.php/topic,2415.0.html

[PZG302]

No need to spend money on the bottom end for a street motor, the standard L series bottom end will handle 6800 to 7200 all day, this is what I have revved my street Lseries powwered cars to for many years.

 

Also not many cams will be making power after 6800 any way unless you go for a custom grind, and then they will be making power that far up you won't have any torque in the mid range making the motor an absolute pig to drive.

 

Unless you spend big dollars on getting the bottom end right by someone who knows L series motors inside out, and I would say there are only a handful of people in the country who do know what they are doing with an L series, don't touch it. I have seen a lot of L series motors brewak cranks and rods because the builder thought they knew what they were doing.

 

I have never touched the bottom ends in any of my motors and not one of them has ever had a problem with crank or rods. I have only ever had one motor, and L22, 4 pot, spin a bearing because it was being used for qualifying for a race meeting with only about 15 minutes run time on it, and the builder rebuilt under warranty as I wasn't given any time to run it in.

 

Jason, Dat2kman has spent a fortune on his L28 to get it to rev to what he needs to be competitive in Group Sc against all the Porsches. He should be able to enlighten you on the costs when he's back from Sandown.

[WogsRus]

Ok so what your saying, is keep a stock bottom end, with new main and rod bearings, from there flat top pistons.

 

Ok so the head then, port and polish, perhaps weld up a little to allow for hight compression, lightened fly wheel, lightened balancer.

 

Decent set of extractors and now for fuel.

 

i have always wanted a set of tipple webers, BUT, cost, the cheapest i can get a NEW set is $1500 with webers from Italy ($890) and a manifold with everything including soft mounts, linkages ect for $400 plus freight.

 

For the same price i can get a new set of SU 240 round tops like i have, or rebuild mine quite easily.

 

How much would going to a tripple weber benefit the car, VS keeping the 240 round tops.

 

Hum decisions decisions

[PZG302]

Ok so what your saying, is keep a stock bottom end, with new main and rod bearings, from there flat top pistons.

Yep, but get the block checked, it may need just a hone or it may need to be bored out. Once you what's what then pistons can be decided on, but flat tops would be the go for mine.

 

Ok so the head then, port and polish, perhaps weld up a little to allow for hight compression, lightened fly wheel, lightened balancer.

For the head, a good service, if needed, new valves and guides, and definately new valve springs. depending the head used, as to what work to do it. I'm not a believer of polishing ports as you need a slightly rough surface to keep the airflow turbulent to get the fuel in better.

 

Decent set of extractors and now for fuel.

 

yes and a well designed exhaust, my preference for a treet motor would be 2 1/4 or 2 1/2 inch system.

 

i have always wanted a set of tipple webers, BUT, cost, the cheapest i can get a NEW set is $1500 with webers from Italy ($890) and a manifold with everything including soft mounts, linkages ect for $400 plus freight.

 

Good price, but make sure the linkages are good quality with good balls for the rod ends, not the cheap plastic ones

 

For the same price i can get a new set of SU 240 round tops like i have, or rebuild mine quite easily.

 

Up to you, performance from the Su's is also quite good, not me experience as all my Zeds have had injection, and my 4 cylinder L series motors have used webers or the standard carbies.

 

How much would going to a tripple weber benefit the car, VS keeping the 240 round tops.

 

Again, need someone else to comment, but for mine a well set up set of Webers can't be beat for noise or the push in the back you get when they open up and the cam comes on.

[WogsRus]

Thanks mate,

 

Yeah i was always going to home the head, i was actually going to bore it out one size up as the machining is free, my mate has a mill and a cnc and a lathe, you name it we can build it.

 

In terms of valves and so forth, the head will be getting new over sized valves as i have a E88 head.

 

I was going to purchase a cam kit from the Us which comes with new aprings, rockers,

 

Hang it, here it is

 

http://www.thezstore.com/page/TZS/PROD/PEM01/10-2000

 

However i have not made my mind up.

 

Flat top pistons will definitely be the go.

 

I don't suppose anyone else has brought a cam kit, complete with new valve springs and so forth?

 

Thanks for the post guys keep em coming

[modular9]

I can only add that the twin su's are great in daily driving ( eg rush hour nose to tail crap ) but the triples... well they are worth it. If you dont strangle them and give them what they want.They pop and bang just like real race cars.  Then that power from around 2500 - 5000 is intoxicating. Very important to get a good linkage system. Go webers over dellortos. A lot of dellorto setups ( mine included ) are using the so called "emission" carbs. B4st4rds to tune. Real b4st4rds. Just personal experience. If I had my time again I'd go new webers over "cheap" dellortos.

[WogsRus]

Thanks mate, yeah i was always thinkgs webers, Found a full Kit in teh US, with manofild, proper linkages carbs and so forth for $1600Au delivered so that' s ok.

 

Also lookign at engine kits, theer is a few manufacturers in the US offering complete engine kits, BUT, is it chepper to buy parts speratly in Oz, who sells stuff for Z's that is cheep, like Bursons and so forth for oil pumps and alike.

 

Does anyone make a VRS gasket kit for a Z.

 

I know i will be using a Nissan head gasket as from what i have read all the others are s h it.

[Ben]

These days I'd go for TBI over carbies - the same noise/power and much better economy (and no leaks!).

[WogsRus]

yeah, but throtle body injection is exy, and if i was doing that iw ould be doing it to an engine i am willing to spend BIG bucks on.

 

And eaven tehn noth worth in on an L series motor, RB for me in that case.

 

Ta

[260Coupe]

The immediate noticable difference between triples (Mikunis in my case) and Hitachi SUs is the throttle response.........SUs work on vacuum alone so you cannot mash you foot to the floor and expect things to happen. Triples not only provide far more fuel/air (six throttle bodies as opposed to two) but as they have accelerator pumps squirting fuel into the inlet manifold, response is (or should be if set up correctly) instantaneous.

 

The difference all round is very noticable and power difference in my engine is around 15-20 rwkw

 

In short .........go triples........and go the new OEM triples available from Les Collins or through Stuart Wilkins in Sydney.......they stay in tune and well priced.(from what I have heard from the blokes in the know)

[WogsRus]

define well priced.

 

A new set with manifold and all the shits and gigles in a 40 or a 45 from the US is $1600 landed in oz.

 

 

[gav240z]

define well priced.

 

A new set with manifold and all the shivers and gigles in a 40 or a 45 from the US is $1600 landed in oz.

 

 

 

That seems well priced to me to be quite frank. I paid close to $1200 AU for Triple 44 Mikuni's that I have no idea what condition they are really in as I've not pulled them apart.