2.8L NA Build-Up What to Expect in terms of HP

[240zip]

I'm the owner of a stock 240Z. I read the threads on the 3.1 Stoker, 2.8L Turbo, and some comments on the 2.8L NA set-ups. It seems for a limited investment, that 1HP per cu. inch is a reasonable expectation. I'd like to get 160 RWHP from my car. My planned set-up is as follows (currently unassembled)

 

2.8L ZX Block (rebuilt with ARP bolts)

E31 head (rebuilt with stock - - cam)

42DCOE-8 Triple Webers (cheap local find - rebuilt)

 

My plan is to add Arizona Z's 6 into 1 headers, a 2.5" exhaust with a 18" resonator and a turbo exhaust. While it doesn't add to HP, my plans are to lighten the flywheel to something like 14 lbs. I have a 1980 ZX five speed transmission, a R200 (3.7) LSD unit from a 1989 300ZX turbo, the CV shaft conversion adaptor, and the 300ZX turbo half shafts. The suspension was completely re-done with new struts, springs, sway bars, bushings, bearings, etc. The brakes were upgraded to cross-drilled rotors and the 4-piston MSA calipers upfront. The rear brakes are stock, but newly rebuilt. The master cylinder is from the ZX. Current plans call for upgrading the radiator to either an aluminum or at least a 4-row version.

 

I have an electric fuel pump and a Filter King fuel filter / regulator. I have a Pertronix Ignitor set-up. All the smog items are going to be removed (no emissions in my county).

 

Right now the CR for this build-up is about 10.3 to 1. That's due to a .5mm over bore.

 

Do you think I can achieve my goal of 160 RWHP? Do people have any suggestions? My goal is a streetable, fun-to-drive weekend car. I know a stroker will make more and I also know that a turbo makes more for less, but I already have nearly all the components that I've manage to collect over the years.

[Silent]

if tuned right, and a slightly bigger cam, i don't see why not

[Austenp405]

You've also gotta keep in mind that here in Colorado, we're definitely starved for air. Also, an N/A Car is going to lose more power at this altitude than one with forced induction.

[pimp1911]

Question. What type of pistons and rods are you using?

[drzed]

Should be easy to get at least that HP level but I would change the following. Forget the ARP fasteners at this level - too expensive. Use the saved money to get a cam reground from Colt Cams here in BC (coltcams.com). Geoff will help you out and he is very reasonably priced -tell him "drzed" sent you. Get an "M445" grind (not his grind number but he will know what I mean). This cam will work well with the carbs you have and the compression level. Watch the piston to head clearance - the last F54 block with flat tops I used had the pistons out of the hole a fair bit.

 

Lastly I would find some 280Z (not 280zx) valves and grind the E31's seats to work with them. If you are getting new seats just get the 280Z seats installed instead. If there is an edge of the head material (in the port) sticking out past the seat grind this off and blend into rest of port. While your in there grind out any casting flange or rough bits. Don't take off too much material just remove any obvious defects.

 

If you get the cam you can't use stock valve springs as they will stack solid at this height. I don't have time right now to go over the whole "how to set up a cam properly" thing but I'm sure it has been explained 20 times on this site better that I could. My personal opinion is that you don't need new rocker arms if your originals are in reasonable shape and I like using L20A outer springs and stock inners if you keep it under 7000RPM.

 

Good luck

[JMortensen]

If you were at sea level I'd say that combo should get you 160whp no problem. I'd also really strongly recommend that you put a bigger cam in it. Running triples on a stock cam gives you a low end cam with top end carbs. Not a good combo. I don't know what effect the altitude has on cam selection so you'll want to check that out before you buy, but you won't get the most from those carbs with the puny stock cam.

 

FWIW I have a L28/E31 with 280 valves, a .490/280 cam and 44s, the AZC header and 2.5" exhaust. I did a lot of port work on the head myself, and it WAY exceeds your goal. I also shaved the head a bit and ended up with more like 11:1 compression.

[240zip]

Concerning the ARP studs - already have them. The short block and the head are done. The E31 head is rebuilt - unfortunately all stock. I have another E31 head that I could (in theory) rebuild with a hotter cam, larger valves, and a mild street port / polish.

 

Concerning the pistons - they are flat-tops, .5mm over.

 

Concerning the rods - they are ones that came with the 280ZX 2.8L block.

[JMortensen]

The stock cam is really going to hurt you. Even if you don't put the 280 valves in the head, you should really consider changing the cam. You're looking at say ~$100 for a regrind, and then factor in $50 for lash pads from Nissan Motorsports and that is probably including shipping on the parts. Resurface your rockers with sandpaper if they need it (http://forums.hybridz.org/showthread.php?t=108404), if not, just run em the way they are. That wouldn't be too hard to do or expensive, and without it the carbs are kinda wasted IMO.

 

It's not hard to do now, but once you have it all back together the reluctance to tear back into it is going to be much harder to overcome. At least it would be for me...

[z-ya]

Jon is right, you will make 160 easy with that setup (as long as it has P79 flat top pistons), but for another $150 you can make a lot more. Plus you wil be able to run a lot more advance. I would run 460 lift max, as you can still use the stock springs. Also, why not just pick up an N42 head, it already has the bigger valves, and it will support an internally oiled cam. Give it a valve job, install the new cam an lash pads, and you set to go.

 

I got 165WHP from a F54-flattop block with a stock N47 head and cam. I could only run 26 deg of advance with high test. If I had a mild cam in there, I could probably push the timing over 30deg advance.

 

I am putting a 460 lift cam in it now, but I'm also swapping to a P79 head, and adding a supercharger. I will make a dyno run with the belt off just to see if I gained anything with the cam and more advance in exchange for CR (was 9.8:1, will now be 8.5:1)

 

Pete

[240zip]

I'm sort of bummed that I have these two E31 heads (one rebuilt), an E88 head, and I think I tossed the stock head that come with the 1980 ZX 2.8L block. The more I read about the E31 heads, the more it seems that it's not such a great head without a great deal of work.

[Pyro]

If you assume that 1:0cr gives about 5% increase in hp then a 10.3:1 would have 10% more power than 8.3:1 cr. And if a stock 75 to 80 L28 (8.3:1cr) makes about 135hp at the wheels then you should be able to get about 149hp. Then a header will add a few more hp 153hp. Close to 160hp. Of course assuming you don't have detonation issues.

 

You need a cam badly to reduce detonation and make that header work for you. Maybe make another 15 to 20hp with a cam (170 to 175hp!)

 

It should be less than 60.00 to get your old cam reground.

 

You need a cam with at about 220 to 230 degress of duration at 0.050".

 

Courtesy Nissan sells lashpads for 3.00/each.

[Mack]

yeah, for all the work you are going to do to the E31, you would be better off getting a Maxima N47, or commonly called the MN47. it has chambers that are actuall a little smaller than an E31, but it already has big exhaust valves. the intakes are small, but with porting, you can get the head to flow decent numbers. I have a few MN47's laying around if you would want to trade one of your E31's,

 

another nice thing about the MN47's is that the valve seats are of the hardened type, and you can run unleaded on them without problems. Im running one on my car and I like it. compression is 11.7:1, a little on the high side, but oh well. it really is a GREAT street perfromer head when mildly worked over. stock, the thing is a TORQUE MONSTER because of the small intake valves = velocity!

[AK-Z]

yeah' date=' for all the work you are going to do to the E31, you would be better off getting a Maxima N47, or commonly called the MN47. it has chambers that are actuall a little smaller than an E31, but it already has big exhaust valves. the intakes are small, but with porting, you can get the head to flow decent numbers. I have a few MN47's laying around if you would want to trade one of your E31's,

 

another nice thing about the MN47's is that the valve seats are of the hardened type, and you can run unleaded on them without problems. Im running one on my car and I like it. compression is 11.7:1, a little on the high side, but oh well. it really is a GREAT street perfromer head when mildly worked over. stock, the thing is a TORQUE MONSTER because of the small intake valves = velocity![/quote']

 

11.7:1? are running a stroker?

[Mack]

nope, no stroker here. thats the compression you get when you put an MN47 head on a stock L28E block with flat tops and a felpro HG. the combustion chambers on that head measure somehwere in the neighborhood of 39CC's. it is a little high and it does ping when the stock ECU reaches its limit. but thats because its running lean. once megasquirt comes into play, along with some turbo injectors, this thing is gonna scream.