now for L28E potential

[Guest 83supaZ]

ok i've seen the post on L28ET potential.. and everytime anyone asks about the potential of a NA L28 everyone says "oh just go with turbo" well what is the potential of a NA L28 with a maxima n47 head, mild cam, forged pistons/rings, running on SU roundtop carbs? what kind of HP you guys think this setup could get?

[Guest Mateo]

Not enough

[Guest 83supaZ]

not enough isnt the answer i wanted though... i wanted to know an approx #. would this push it up around 200 hp? what other things could be added to the setup i mentioned to add more HP?

[datsunlover]

Well, I'm gona be building something like this, cause I can't affort an L28ET right now.. From what I've gathered, I can take my 75 280z's engine, install 240 rods and flat top pistons, shave the head slightly, and with port matching of the intake/exhast manifolds as well as a 2.5" exhast.. And I'll be running my 72 SU round tops. This will suposedly put me at 225 or so HP (taking this from a few sources) and with a 3.90 rear gear and 5 speed, I'm assuming this will make my car fast enough to pucker my arse just fine.

Im not sure if the N47 will flow better that mine.. (?) and I honestly don't know what I'm gona do for a cam yet, (might use my stock one, just polish it) but I guy here I've been talking to seams to know his stuf when it comes to N/A motors. Goes by ZR8ED. Seriously, he's said something about an 8000 RPM 300Hp N/A motor. Maybe drop him a PM.. or maybe he'll see this post and get involved.

[BleachZee]

You guys are probably looking at 150-160whp.

 

A shaved head with large intake valves, BIG cam, tight springs, major porting, balanced lower end, and tripple sidedrafts can yield just barely 200hp with a 4.11 rear at 7,000rpm

[Drax240z]

I don't see you making 225hp with the stock cam and SU's.

 

A hot 2.8L setup with SU's and lots of other performance work done will probably be in the 170rwhp area. Add another 30-40hp to the top end with a well tuned set of triples. (only if you've allready done cam, exhaust, ignition, etc) Tack on another 20-25hp or so if you are running a 3.1L setup.

 

Rules of thumb. Actual dyno results vary A LOT from dyno to dyno, and engine to engine.

 

Datsunlover: do yourself a big favor and get a cam. Check out Colt Cams in Vancouver, and order a "Shadbolt M445" grind and you won't be dissapointed at all.

[johnc]

A hot 2.8L setup with SU's and lots of other performance work done will probably be in the 170rwhp area.

 

A well prepared ITS or BSP spec 2.8L engine (stock cam, stock head, stock pistons, headers, SU carbs, unmodified intake) will make 200 hp on an engine dyno which works out to about the whp number mentioned above.

 

A well prepared E Production 2.8L engine makes about 250 to 260hp on an engine dyno. That's with 12:1 CR, slightly modified heads, special cam, headers, modified intake and SUs, and other simple performance mods.

 

A cheap parts rebuilt 2.8L with a cam, head work, etc. will be lucky to equal the power of the well prepared ITS spec 2.8L that used stock internals.

 

Throwing parts at an engine to increase horsepower rarely works.

[JMortensen]

A well prepared ITS or BSP spec 2.8L engine (stock cam, stock head, stock pistons, headers, SU carbs, unmodified intake) will make 200 hp on an engine dyno which works out to about the whp number mentioned above.

 

A well prepared E Production 2.8L engine makes about 250 to 260hp on an engine dyno. That's with 12:1 CR, slightly modified heads, special cam, headers, modified intake and SUs, and other simple performance mods.

 

I agree with the above, so I think the proposed engine will fall somewhere in between. I really think the stock cam is not very big, and I would encourage anyone doing a buildup to get a bigger cam.

 

A cheap parts rebuilt 2.8L with a cam, head work, etc. will be lucky to equal the power of the well prepared ITS spec 2.8L that used stock internals.

Throwing parts at an engine to increase horsepower rarely works.

 

Maybe this is true, but I don't think that's what we're talking about here. You're comparing an ITS 280 engine with 8.3:1 to a 10.8:1 forged piston 2.8 engine. From the original post...

 

...a NA L28 with a maxima n47 head, mild cam, forged pistons/rings, running on SU roundtop carbs? what kind of HP you guys think this setup could get?

 

And now my issues with the idea: Max N47 head...hmm. I wouldn't just use the Max N47 head. Definitely install the larger 280Z valves and port the head to make them work, and now you've got a high compression engine with a good chamber design. Forged pistons doesn't sound budget to me.

 

I think the things missing here are PORTING the head to fit the bigger Z valves, and a bigger cam. The SU's are going to be a restriction too. Get a set of ported SU's with the above and I think you're talking 210-220 bhp.

 

As Drax said add triples and gain another 30-40 hp.

 

I think if this is done RIGHT with SU's and a cam and some headwork it should be NO PROBLEM to exceed the ITS engine...

[datsunlover]

I forgot to mention that A; I was planing on boring out my SU's a bit, and B; I have come across some paper work on my car (from the previous owner) that suggests the cam is NOT stock. I'll have to see when I tear the thing down. Also, I was talking about HP AT the engine, not wheel HP.

And considering MY engine says it's rated for 170 (which I know is not at the wheels) AND my engine is.. well, hurt.. Anywhere near 200HP is gona be a BIG improvement. Ok.. 200 or so horse isn't "a lot" of power.. but I figure my 75 moves ok as it is.. and my guess is it's only puting 120-125 down to the wheels right now.

[johnc]

You're comparing an ITS 280 engine with 8.3:1 to a 10.8:1 forged piston 2.8 engine

 

Those ITS engines are all built to the max CR allowed: 9.5:1. That number is reached with head milling, projector tip spark plugs, and other tricks.

[JMortensen]

OK thanks, I stand corrected. I thought the 240 engines were allowed 9.5 because that was stock + 1mm overbore. I didn't know you could mill the head to get the compression on a 280 engine.

 

Still think with a cam and the extra point compression and all it should be fairly easy to beat the ITS motor. That stock cam sucks. When I was deciding to change mine I read so many stories of "no bottom end" or "don't go too big" etc that I was really afraid to change it. Going .490/280 on my cam made a nice difference on the SU's, and IMO is really the minimum necessary for triples.

[Dan Baldwin]

You don't need forged pistons, save your $$$. As for what hp you *could* get (possibly very different from what you WILL get), I'd say 180+rwhp/210crankhp is certainly achievable. I'd definitely go with the bigger 280Z/ZX valves (not sure which you should use in a Max head, though...), or just use an N42, N47, shaved P79, shaved P90.

 

JohnC,

You sure the 280s can have the same 9.5:1 CR as the 240s?

 

ok i've seen the post on L28ET potential.. and everytime anyone asks about the potential of a NA L28 everyone says "oh just go with turbo" well what is the potential of a NA L28 with a maxima n47 head, mild cam, forged pistons/rings, running on SU roundtop carbs? what kind of HP you guys think this setup could get?

[johnc]

JohnC,

You sure the 280s can have the same 9.5:1 CR as the 240s?

 

You guys are right. Basically you're allowed .5 over what's listed in the ITCS - which for the 2.8L engine is 8.3:1. Max allowed would be 8.8:1.

[Guest 83supaZ]

well im going to get the 280z valves put in the max head... forgot to put that.. also get a 2mm HKS head gasket to help lower the compression enough to prevent detonation.. i've seen a few people with this setup and they said it was better than the p79 head setup. when u say bore out your SU's u mean the intake right? the max head will work with SU's correct? and what cam would you guys suggest? is the Stage 3 cam on MSA good? Too much for my setup? I belive its .460/.460 also.. shaving my head would be the same thing as getting the maxima head basically.. only you dont have to spend the money to shave and shim everything up....

[JMortensen]

2mm headgasket is a bad idea IMO, search on "quench" to find out why. You'd be better off doing a shaved P90 and using a standard gasket, plus you wouldn't have to pay near as much to get the head shaved as you would to have the larger seats installed.

 

460 cam is not much better than stock IMO. I ran my .490/280 with SU's and it idled a little lopey but had plenty of grunt and better top end. Carbs still limited it A LOT. Switched to triples and could slam against the rev limiter instead of touching the rev limiter.

[Guest 83supaZ]

the max heads only have a 39cc combustion chamber but the same combustion chamber design of late model zx heads.. compression would be too high without using the 2mm HG i believe.. with it i think CR would be around 10.7.1 *dont quote me* smaller combustion chamber=more combustion... smaller combustion chamber=less compression you need because of less quench area

[Guest 83supaZ]

"smaller combustion chamber=more combustion" i meant to say =more compression.. my bad...

[Guest 83supaZ]

what about a .495/.290 cam? the one on MSA or would you guys recommend a dif namebrand cam?

[Mack]

well, being one of the only people on here to actually RUN a maxima N47, Ill chip in my 2 cents worth here.

 

NOTE: Maxima N47 will be referred to as P47 through out the post.

 

THe P47 and N47 have the same valve stem heights, so, when I had my P47 in the shop, they were able to machine the seats and install my old N47 big intake valves with no problems. The whole reason I went with the P47 was because my N47 (1980 280zx) was in neeed of $300 worth of welding to repair corroded water passages. and it was warped .018". then the bottom end ended up being crap too, so I bought an 82 parts car.

 

So, I had this flat top P79 motor, and this summer I installed a P47 head, with a FELPRO gasket (.8mm compressed height) With the felpro, I am getting the benefits of "quench", being there is less than .040" between the piston and the non combustion chamber parts of the head. I also used a 260Z "C" cam and blended the area above the exhaust valve into the liner, as well as took out some sharp ridges just above the intake valve. I also intalled a 60mm TB, 2.5" cat back mandrel bent exhaust and removed the "bumps" for the injector hold down screws in the intake manifold. I am also running a 3" press bent intake witha cone style filter on it.

 

with all this work done, I must say the car pulls MUCH harder than ever before, in all gears and it pulls HARD past 6000. I have yet to take it to the track, but rest assured I will when I get the chance.

 

With the P47, on a flat top with the .8mm felpro gasket, I calculate my compression ratio to be about 11.2:1 (assuming a 40cc combustion chamber). I used MIDGRADE gas, no ping, timing set to 15* initial (go quench area!, lol) total machine shop bill for unshrouding valves, installing larger valves, cleaning 2 heads (dead N47 and P47) and resurfacing the P47 was $250. try doing that with a hsaved P90/P79. plsu, I didn't need to mess around with cam tower shims, thicker lash pads or any of that other extreme head shaving related crap.

 

McAdam

 

p.s. sorry for the long winded post, and yes, the P47 has all the bolt holes for BOTH carb and FI intake manifolds.

[JMortensen]

Mack, I'm glad you're happy with your new engine, sounds like a screamer. I do have some concerns about your post, and please correct me when you think I'm wrong.

 

With the P47, on a flat top with the .8mm felpro gasket, I calculate my compression ratio to be about 11.2:1 (assuming a 40cc combustion chamber). I used MIDGRADE gas, no ping, timing set to 15* initial (go quench area!, lol) total machine shop bill for unshrouding valves, installing larger valves, cleaning 2 heads (dead N47 and P47) and resurfacing the P47 was $250. try doing that with a hsaved P90/P79. plsu, I didn't need to mess around with cam tower shims, thicker lash pads or any of that other extreme head shaving related crap.

 

1. You CAN install the N47 valves in the P47 head by just cutting the seats to fit the N47 valve head, but you can also do it the way I did on my E31, by putting a larger seat in the head and porting the runner to match. The bigger valve in the P47 would flow a little better, but having the larger seat and port would do more.

 

2. Unshrouding my valves took out 4 or 5cc IIRC on my E31. Not sure how much you took out on your head, but I'm guessing more than 1 cc. I suppose this is going to vary on who does the work and how aggressive they are with it. I thought I took a lot out, but I don't have anything to compare against. I also eyebrowed the block, which might have a tiny tiny effect too. Just for comparison, the P79 shaved .080 has about a 46 cc chamber according to this site: http://www.geocities.com/zgarage2001/head.html So if you or your machinist was as aggressive as I was, you might end up with just about the same chamber volume as the shaved P90.

 

3. If you shave a P90 .080 and use the N47 valves, you don't have to mess with the lash pads. You do need to get cam tower shims. Last time I got a price on them they were ~$20 for a set, and that set was .015" thick. You could theoretically stack 6 sets of those, or perhaps find some others that were thicker to start. I didn't look for different thicknesses much at the time because I didn't need to.

 

4. The benefits of the P90 is that there is less work to do to it. The compression isn't as high to start with. Unshrouding the valves isn't necessary due to the fact that it already comes with a chamber properly shaped for the larger intake valve (there might be something to be gained here anyway, but it isn't a neccessity). Larger seats and intake ports. The only machine work necessary is the shaving of the head.

 

I think what you have done is very similar in the end result to the shaved P90 setup. The differences are that you have smaller runners, and that you might have a 2 or 3 cc smaller chamber.