Guest angryAJmonotone Posted June 13, 2003 Share Posted June 13, 2003 I just tbought a 79 280zx, im wanting to keep it original and normaly aspirated. For simplicity sake, I am thinking of switching to a holley 4 barrel carb. I am wanting to put flathead piston, and a stage 3 cam from motorsport, I am also planning on giving it headers and exhaust. and 4.11 gears, and a dual friction clutch. Has anyone done a similar buildup, or any recomendations, i am new to the z car world so any advice would be appreciated. thank you AJ Quote Link to comment Share on other sites More sharing options...
Guest eric-z Posted June 14, 2003 Share Posted June 14, 2003 what kind of head do you have on your zx? if it is a P79 or P90, you can find a N47 or N42 head and that will up your compresion. datsun engines respond well to higher compresion from what I hear. with flat top pistons you should be getting a little higher than a 10 to 1 ratio. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 16, 2003 Share Posted June 16, 2003 I've done an n/a buildup beginning with my '80 zx, then later took the engine out and put it into a '72 240. Well you sound set in that you dont want to go turbo, but I will tell you, you have to have realistic goals for what you're going to accomplish with just building up an N/A 2.8 motor. Which really isn't much, but even worse, is that it's going to cost a lot of cash to get there, and in the end you're still going to have a slow car by todays standards, or a moderately quick one at best. For one, DO NOT get the holley conversion....... Due to the length of the straight six engine, you can't possibly get a holly setup to run evenly on all 6 cylinders, and that is bad. You're gonna run rich on the #3 and 4 cyls, and too lean on numbers 1 and 6...... this is not good for performance. And you say you want to stay original... how is a holley original? I believe most people here would back me up on this, the holley is not a step up, performance wise.... if you want simple and efficient put SU's. Plus putting a holley is not smog legal, as far as I know. If smog is not an issue, and you want a simple carbed setup, then get SU carbs. They are very easy to understand and tune. But I can tell you from experience on this too, that your'e better off staying with the EFI. About the head, yes you can get higher compression and a bit more power with the N42 head (this is what I put on mine, though I regret it now) but be careful, N42 head with flattop pistons can be way too much compression and will give you detonation problems, you're gonna need to be able to adjust your fuel flow to compensate (again, do not do this by swapping to a holly carb!). There's also some OVERWHELMING evidence suggesting that the P79 and P90 heads are actually better heads, do to the shape and design of their combustion chambers. The P90 was the last head designed for the L series engine, and was the head used on turbo engines, which needed better flow, and was a culmination of design points from all the earlier heads....... I really believe this is the best head. If you shave it and shim the cam towers to get around the same compression as an N42, I think you would get better performance overall. For the cam, be careful with cam selection if you want the car to behave well on the street. I went with just a mild cam, what woudl equate to a 'stage 1' or 'stage 2' from MSA, and it can be a pain on the streets sometimes. The power doesn't come on until about 3k rpms, so for street cruising if I suddenly need to GO I need to downshift. But I dont regret this cam, I think it's a good all around cam. Not sure what specs are on a stage 3, but if my guess is right you wounldn't want this for street driven car. By the way, to dispell a common myth, cams dont necessarily give you MORE power..... a stage three wont really put more down to the ground than say a stage 1, all its gonna do is move your powerband higher up in the rev range. Anyways.... just to give you an idea of what your'e getting into, I will give you details of what I did. I took a '78 280z block, rebuilt it, bored it out .060 over (which makes a 2.8 into a 2.9 liter), and put flattop pistons in it. Mated that to a rebuilt N42 head with comp valves and minor porting and polishing, and the mild cam. Put headers, exhaust, lightened flywheel, ACT six puck clutch, 3.9 rear end gear, big bore throttle body and K&N filter, and an adjustable fuel pressure regulator. This setup cost me around $4 grand, and made 145hp and 160ft lbs of torque on a dyno. This was in my ZX with the fuel injection. Before putting the fuel pressure regulator, the car would ping insanely at anything over 4500 rpm. Also, you will need at least 91 octane gas to run this high compression, and that would be with retarded timing and running a little rich. When I put the same engine into my 240z, and swapped out the EFI for SU carbeurators with SM fuel needles, torque stayed the same but hp jumped up to 160hp. This ended up with a decently quick 240, which will do 0-60 in a moderate 6.5 seconds..... but mind you this car weighs 2300lbs, in a much heavier 280zx you're looking at more like mid to high 7 second 0-60 times, not even on par with todays sporty compact econo cars. The SU's also cost me another $700 to buy rebuilt ones (finding good used ones that dont have vacuum leaks is a gamble at best). Although they did make a little more power I think this was in part due to my EFI running buggy, it had problems that I never was able to figure out. The negative side was my gas mileage now SUCKS. Now I find that for abou $3000 (it would cost me MUCH less if I had the tools/ability to do the labor myself) I can put a 280zx turbo engine into my car with a few go fast goodies, raise the boost to 10psi, and put an estimated 200hp to the wheels, and with another $1000 or so (this would put me close to what I've already spent on this N/A engine) I can add some more parts like an intercooler, fuel pressure regulator, and bigger injectors, to get me closer to 250 at the wheels and have a car that will do 0-60 in about 5 seconds and mid to low 13 second 1/4 miles. This will be faster than almost anything else on the street. AND I'll get all this with much better gas mileage. I have kicked myself so many times for not just doing this to begin with. Even in the heavier ZX, 250hp is nothing to sneeze at, and putting a turbo into an n/a zx will be even easier than what it's gonna take to put it in my 240..... you've got the better starting point. The only way you're gonna get anywhere near that kinda power out of an N/A is to have a stroker built, which is gonna cost way more, at least $5,000 to do it right the first time. If you just want a bit more power than sure building up your N/A would do the trick but if you want a fast car..... dude dont make the same mistake as me and pour money into an N/A that will probably never be as fast as you want it to be. Just my .02 cents Quote Link to comment Share on other sites More sharing options...
Tim240z Posted June 16, 2003 Share Posted June 16, 2003 I've done an n/a buildup beginning with my '80 zx, then later took the engine out and put it into a '72 240. Well you sound set in that you dont want to go turbo, but I will tell you, you have to have realistic goals for what you're going to accomplish with just building up an N/A 2.8 motor. Which really isn't much, but even worse, is that it's going to cost a lot of cash to get there, and in the end you're still going to have a slow car by todays standards, or a moderately quick one at best. For one, DO NOT get the holley conversion....... Due to the length of the straight six engine, you can't possibly get a holly setup to run evenly on all 6 cylinders, and that is bad. You're gonna run rich on the #3 and 4 cyls, and too lean on numbers 1 and 6...... this is not good for performance. Plus it's not smog legal, as far as I know. If smog is not an issue, and you want a simple carbed setup, then get SU carbs. But I can tell you from experience on this too, that your'e better off staying with the EFI. About the head, yes you can get higher compression and a bit more power with the N42 head (this is what I put on mine, though I regret it now) but be careful, N42 head with flattop pistons can be way too much compression and will give you detonation problems, you're gonna need to be able to adjust your fuel flow to compensate (again, do not do this by swapping to a holly carb!). There's also some OVERWHELMING evidence suggesting that the P79 and P90 heads are actually better heads, do to the shape and design of their combustion chambers. The P90 was the last head designed for the L series engine, and was the head used on turbo engines, which needed better flow, and was a culmination of design points from all the earlier heads....... I really believe this is the best head. If you shave it and shim the cam towers to get around the same compression as an N42, I think you would get better performance overall. For the cam, be careful with cam selection if you want the car to behave well on the street. I went with just a mild cam, what woudl equate to a 'stage 1' or 'stage 2' from MSA, and it can be a pain on the streets sometimes. The power doesn't come on until about 3k rpms, so for street cruising if I suddenly need to GO I need to downshift. But I dont regret this cam, I think it's a good all around cam. Not sure what specs are on a stage 3, but if my guess is right you wounldn't want this for street driven car. Anyways.... just to give you an idea of what your'e getting into, I will give you details. I took a '78 280z block, rebuilt it, bored it out .060 over, and put flattop pistons in it. Mated that to a rebuilt N42 head with comp valves and minor porting and polishing, and the mild cam. Put headers, exhaust, lightened flywheel, ACT six puck clutch, 3.9 rear end gear, big bore throttle body and K&N filter, and an adjustable fuel pressure regulator. This setup cost me around $3-4 grand, and made 145hp and 160ft lbs of torque on a dyno. This was in my ZX with the fuel injection. Before putting the fuel pressure regulator, the car would ping insanely at anything over 4500 rpm. Also, you will need at least 91 octane gas to run this high compression, and that would be with retarded timing and running a little rich. When I put the same engine into my 240z, and swapped out the EFI for SU carbeurators, torque stayed the same but hp jumped up to 160hp. This ended up with a decently quick 240, which will do 0-60 in a moderate 6.5 seconds..... but mind you this car weighs 2300lbs, in a much heavier 280zx you're looking at more like mid to high 7 second 0-60 times, not even on par with todays sporty compact econo cars. Now I find that for a mere $3000 I can put a 280zx turbo engine into my car with a few go fast goodies, raise the boost to 10psi, and put an estimated 200hp to the wheels, and with another $1000 or so (this would put me close to what I've already spent on this N/A engine) I can add some more parts to get me closer to 250 at the wheels and have a car that will do 0-60 in about 5 seconds and mid to low 13 second 1/4 miles. This will be faster than almost anything else on the street. I have kicked myself so many times for not just doing this to begin with. Even in the heavier ZX, 250hp is nothing to sneeze at, and putting a turbo into an n/a zx will be even easier than what it's gonna take to put it in my 240..... you've got the better starting point. Anyways, hope this rant helps Yeah...read that again....words from the wise!! Tim Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 16, 2003 Share Posted June 16, 2003 TIM!!! You get that awesome beast of a Z running yet?? I've been dying to see it again..... I keep missing your barbeque's man WORK SUX. Maybe by the time you have another one I'll have my turbo done..... (crosses fingers) I'm lookin at about 2 months UGH...... Quote Link to comment Share on other sites More sharing options...
Tim240z Posted June 16, 2003 Share Posted June 16, 2003 You'll probably have yours done before mine......as soon as I think I'm on the home stretch, somethin else pops up that I hadn't anticipated..... Tim Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 16, 2003 Share Posted June 16, 2003 ugh sorry to hear it..... well if it's any consolation, I always having nothing but bad luck especially when it comes to my car and anything involving making it faster! I don't want to admit it to myself but I'm sure that something is gonna come up with this swap too...... everything always takes 3x longer than expected. Swapping my 2.9 into the 240, and getting it up and running..... ugh....... but this time I'm crossing all fingers and toes..... please let it go smoothly. Quote Link to comment Share on other sites More sharing options...
johnc Posted June 16, 2003 Share Posted June 16, 2003 There's also some OVERWHELMING evidence suggesting that the P79 and P90 heads are actually better heads, do to the shape and design of their combustion chambers. Really...? Overwhelming? Seems that Jim Thompson, Don Devendorf, John Caldwell, Don Potter, and Dave Rebello have all missed that overwhelming evidence. I guess I'll send my engine back to Sunbelt. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 17, 2003 Share Posted June 17, 2003 yes overwhelming evidence SUGGESTING not overwhelming PROOF OF like I said I have an N42, and it's a good head.... you dont see me scrambling to go out and get a P90, and it is much easier to just stick on an N42 on than to take a P90 and shave and shim it, but there's gotta be a reason that most modern cars (at least modern cars that I've seen the combustion chambers on) have the same heart shaped chamber that the P90 has, and not the more circular N42's chambers. That's also not to say the N42 is a bad head by any means, it's just that after reading 10,000 websites and forum debates, and seeing how many lean towards the P90 as the better head, I find it hard not to believe. And when I see so many more FOR than AGAINST, to me that is OVERWHELMING. As far as all the names you listed, those guys have been buildiing performance engines for ages, and most people seem to think/agree that guys like that can get pretty set in their ways. Most of those guys also probably used to use the now-rare E31 head (think it was E31? really high compression). Because it is easier just to put one of these on and BANG instant high compression, and increased power. Whereas you cant just slap a P series on there and get that, you have to work it first to get that same compression. Also I do believe very strongly that the P90 head would be a much more detonation resistant head in high CR applications, and I know for a FACT that the N42, MY N42, had massive ping problems when i put it on, requiring a much richer mixture and retarted timing. And anyways I'm not trying to open the can of worms that this subject always seems to do, just giving my opinion, the evidence is there for anyone who's willing to be open minded and look into it. A great place to start would be Bryan Little's website, which you can find here: http://www.geocities.com/zgarage2001/z.html Quote Link to comment Share on other sites More sharing options...
johnc Posted June 17, 2003 Share Posted June 17, 2003 Dang! I was hoping to get the pointless, circular N42 vs. P90 debate going again. BTW... Electromotive (Don Devendorf) preferred the P90 head for their turbo charged race engines and, supposedly, was involved in Nissan's design of that head for the ZXT. And you're right. Engine builders do get set in their ways. Unfortunately, neither the 280Z or the ZX is competitive in Improved Touring and neither is eligable for any other SCCA race class (excluding GT categories which allow extensive head mods) so there's really no competitive development effort by the Sunbelts and Rebelllos on the P79/P90. Its potential in comparison to a fully developed N42 (which is basically just an E88) will probably never be verified on the racetrack. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 18, 2003 Share Posted June 18, 2003 LOL well you can start it but leave me out of it! But thank you for even furthering what I was saying..... the P90's potential hasn't really been tapped into by those guys that build race engines, because until now they've had no need to or in the case of what you are saying, wouldn't be allowed to use what they build. Look, I wont even argue the fact that the P90 supposedly flows better, I havent seen any 'proof' to that point, so I've no reason to believe either way, the only reason I would personally choose the P90 over the N42 if I had the choice to make again, is the combustion chamber shape, which is something anyone can see for themselves. That heart shaped chamber makes all the difference in how the air and fuel gets sucked into the cylinder, and how it gets squished up to meet the spark plug, and I think that alone would result in better, more even burning mixture, and thus more power. Quote Link to comment Share on other sites More sharing options...
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