Are my expectations too high?

[ZHoob2004]

A p79 head might help. The valves are bigger and with flat tops compression would be pump gas friendly. I had an 83 5 speed f54 flat top /p79 with megasquirt it was not the fastest car but very fun to drive.

 

Unfortunately, this would require me to source either pistons or a 3rd complete block, neither of which I am fond of doing at this moment. 

 

What Tony was saying is true, on top of that the stock EFI is probably limiting you. 

 

Here is my dyno of an stock L28  (f54/p79  combo) with SU's and a 6-2-1 msa header

 

 

 

You can see it falls off. 

 

One other thing I can think of is the weight difference. I know the CRX's weigh like 2300lbs tops fully loaded. Your Z is a little heavier than that. My engine is in a 2100 lbs 240z. 

 

That makes sense, and I'm grateful for the information.

[Greeko]

I had a b18c CRX back in the day and I now have a 1978 Datsun 280z... The crx was fast if I could get traction but my Datsun is much much faster!!!

 

I did however pull out the stock L28 because my horsepower goals for a NA L28 would cost me $10000 in rebello parts, machining and bits/pieces.  I opted out for a $4000 fix. A 1JZ with standalone management. I now run 338 hp at the wheels at 12 psi and she is a BLAST to drive.  If you want to stay with the stock L28..maybe do a turbo option? Maybe thing about a 280zx turbo swap?... there are a couple for sale on the forums...

 

Good luck

[supernova_6969]

SO i was thinking, the work you did on your engine is not so much tunning as a tune-up.  if you did that properly, you brought the engine back to stock power at least, and maybe added a few HP.  but I wouldn't expect more than 5-10 more than stock from simple cleaning/tuning.  

 

the exhaust might give you a few more, but not that many either.

 

with the stock computer, you won't be able to do more than that.  having an AFR might tell you whether the stock ECU sends it enough fuel, but you won't be able to change the amount of fuel based on your needs.  the stock ECU is untunable.  

if you get yourself a programmable ECU (megasquirt, wolf(?), haltech, you name it), AND an AFR meter, you can continue to tune it a little more scientifically, making sure the engine is not too lean, not too rich anywhere (remember, most places say that cruising should be between 14.5 and 15.5 for fuel economy and around 13.5 for max power/acceleration).   HOWEVER, making certain you're neither rich nor lean does not make your engine make it's max power;  it just makes certain you're not blowing it up for being too lean or wasting gas and fouling up your plugs from being too rich... 

once you're kindof tuned to the right AFR, to get the most out of the engine, you need to get it on a dyno, where a pro can fine tune it to what you want (low- med or high-end power/torque), making it potentially gain up to 10-20 hp/trq in certain places on your curve, depending on how good (how lucky) you did on the tuning to begin with. 

 

now, while you are at it, if you add cams to it, some porting and all that, well, the sky is your limit. well until something blows.  the one thing you have to consider is no matter where you're going, you'll need to be able to tune the amount of fuel you're sending in there.  that comes first.  once you buyu that, you can either tune it as it is and keep it like that until you buy and install new parts, or if you are rich, you can buy it all at once and just go for broke.  

 

all that said, if you go for broke, you might literally break your engine.  with a nice cam and tune, you can bring the engine to relatively high power and the old stock might strain at the seams from that.  then again, the L6s are knows to be rather solid... 

[ZHoob2004]

It's taken about twice as long as I said it would but I'm back wrenching on the car today. I just looked at the cam in the motor and it's internally oiled and stamped "A", which should put it as a later n47 cam, same specs as my other one and not the maxima cam. I'm going to verify the cam timing right now and get my wideband install finished.

[ZHoob2004]

Well everyone, I've found the magic. Since the cams didn't turn out to be the problem, I moved onto the next step, the AFR. I got my exhaust welded the other day and I finished installing the wideband today and now I feel like an idiot. Motor was SUPER lean (>20:1 AFR) all over the place, no wonder it drove like garbage. I decided to take a look at the questionable wiring on the injectors and as soon as I touched one I heard the engine sound change and saw the AFR improve. Based on that, I cleaned and reseated the injector wiring and I'm now running a nice ~14.5 at idle with good AFR and power all around.

 

After fixing the fueling problem, the motor is butter smooth and the power is right where I imagined it would be. I feel kind of stupid for not noticing that the motor was running so poorly but I'm going to attribute it to being used to 4 cylinders and not realizing how smooth the l6 can be. Thanks again for all the suggestions, everyone.