ozconnection

There's buggar all difference in those curves that I can see. Costs and underbody fitment might be the next issues to consider.

239.000 miles......still under warranty......contact Nissan ASAP to receive your replacement. How is your water pump? Do you have enough coolant in your radiator and overflow bottle?

Yes, a 240Z auto (3n71b) will bolt to the back of an L28. For serious dragging with consistancy, why would you run anything else? Good idea and good luck.

:tapemouth Do not destroy an EFI pump by trying to modify it. I agree with Z train. I ran an efi pump with a carb once, and like Doradox, I ran a return line back to the tank, in fact it was already there and it was a 1/4 inch line. I ran a Holley carburetor and the resulting pressure didn't flood the carb. The ONLY mod I made was to cut off the restriction at the end of the return fuel line rail, so there was no restriction in the return line that would, for a low pressure pump, provide the carb with the needed 4-4.5 psi fuel pressure. Cheers mate.

I'm glad that someone decided to use an O2 sensor to determine what was happening at idle. Not so long ago, the "top" tuners would have an educated guess as to what was needed and if they were right, he was the guy to go to. Now average guys like us, can diagnose and get it tuned right. Superb gentlemen!

forgot about that one....can I thumb a lift with you?

I will second this motion Z train! One of the best conversions I ever did on my L28 was to convert to a 280zx distributor. C'mon people, I've said this before, these cars aren't Geo Metro's, they're sports cars! Give 'em what they deserve and upgrade into this century. No one has to know if you don't open your hood.

Yeah, that's a good call Zed Head. I'll see what I can dig up and photograph and measure. I'll post up ASAP.

Yep, that's probably true and the reason why there is such a jump in power with modifications. Seeing the results were so encouraging was more than enough for me to continue searching for more power. Cheers. PS Nice thread on Cedrics, thanks!

Have a look in my 'garage' These old Datsuns (Nissan Cedric's) were once common sights all over the world except the USA. They were used as Taxi's in Japan and south east Asia including Australia and New Zealand.

Interesting. The engine bay plate from Nissan says that my L28 produces 139HP @5200 rpm SAE. How can it possibly be expected to put 130HP to the wheels then? The results I'm getting are all through an AUTO trans too btw. Hmmmm.

At the wheels? There could be a number of valid reasons why my dyno figures appear to be low compared to what you would expect from an L28. Perhaps the most important thing to realise is the relative changes to the power output since the actual figures are really not that important, but the changes as seen as percentage change is what I'm trying to demonstrate. ie the effect the modification had to the engine and how it responded to those changes. Zedhead, the year model is 1978.

I was in the middle of modifying my post, 60 minutes had come up and this is where I'm up to. I had to write to admin about it. I'll see what happens. Sorry for the hiccup people. You live, you learn. Ah, I cut and paste....... What you've just read is my last post in another mans thread. I posted a dyno graph of my results there too. It has three power pulls, two are obvious, the third is the less so, it's the curve that peaks at 65 kw on the power graph. Ok, there is some expaining to do here. The baseline pull which peaks at 60 kw's was a stock L28S (single carburetor) engine mated to an L3N71B transmission and a H190 differential. Wheel size was 205/70/14. The pull was done in second gear, the transmission does not drop to 1st at all, even when at standstill! That's a very convenient feature.The distributor was also a 280zx unit where the original one was a single points unit. The line that peaks at 65 kw's is a run that was done by replacing the standard Hitachi vac secondary two barrel (very similar to what is found on 510's) with a 4 barrel Holley 600 cfm vacuum secondary carburetor using two adapter plates to mate it (the carb) to the stock Y41 intake manifold. Ah ha you all say, the bastard is lying to us and trying to fool us.....not so people. Look carefully. There was an improvement but its 5 kw's or 8.3% at the wheels. Not massive considering the relative size and flow capacities of the two carbs. I interpret this result as a situation where the engine could perform better if it wasn't strangled by the small exhaust and stock exhaust manifold. I make this conclusion because as soon as the headers and 2.5 inch exhaust with two mufflers are bolted on, there's a jump to 80 rwkw's, up from the previous best of 65 rwkw's. That's over 20% people. Cheers.

The purpose of this thread is to continue a comment that I made about the benefits of modifying the original Datsun L28 exhaust setup and replacing it with headers and a bigger single system. When I was much younger and first started playing around with cars, my mates owned a lot of Fords. They started with straight 6's and moved on to Cleveland and Windsor V8's. Whenever they bolted headers to their cars we could see/feel the difference, cause we were all naughty and raced each other on the street to see who had the quickest/fastest car. "Last week Pete was slower than George but this week, since he's put those headers on....oh boy!" The increases may not be there on 'other' vehicles that you've seen or worked on but with Fords there are significant performance gains. Getting back to Datsuns, I modded my car at the same time and found exactly the same thing was happening. That sweet little L series (little compared to the Ford stuff) came alive with any sensible part upgrade but up until a few years ago, I could only talk about it and not prove it. Then I got myself a stock Datsun with an unmodified L28 and thought, "I'm gonna document every change I make to this engine and dyno it every time to see what my butt dyno feels!" So, I have a dyno sheet that shows the difference what headers and a nice exhaust make to the L series. The original exhaust manifold and 1.75 inch was replaced by a set of HM39 (Aussie brand) and a 2.5 inch exhaust with two mufflers. I don't want to shoot my own argument down here by saying that the discussion only involves headers and not the rest of the exhaust but I kinda see it as a whole package really. If you didn't want to upgrade the whole pipe and muffler shebang your power gains probably won't be as much as mine. Still worthwhile?.......absolutely. What you've just read is my last post in another mans thread. I posted a dyno graph of my results there too. It has three power pulls

Hey, this seems like a bit of a threadjack.......I'm dumping a whole lot of 'stuff' on here that in no way relates to the original posters question. I'm sorry about that. Andy, I'll answer your question but I might start my own thread and we can discuss my results further if you wish.

Hey, the front bars on my Cedric ARE Roo Bars (they're big enough), a second set would be nice. Thanks! Yeah, it's an N42 block like yours. Have fun with the construction phase mate. Cheers.

That looks fantastic Guy! Brass and steel core plugs? Reminds me of my engine, complete now, just waiting on the correct balancer to arrive and in she goes....

When I was much younger and first started playing around with cars, my mates owned a lot of Fords. They started with straight 6's and moved on to Cleveland and Windsor V8's. Whenever they bolted headers to their cars we could see/feel the difference, cause we were all naughty and raced each other on the street to see who had the quickest/fastest car. "Last week Pete was slower than George but this week, since he's put those headers on....oh boy!" The increases may not be there on 'other' vehicles that you've seen or worked on but with Fords there are significant performance gains. Getting back to Datsuns, I modded my car at the same time and found exactly the same thing was happening. That sweet little L series (little compared to the Ford stuff) came alive with any sensible part upgrade but up until a few years ago, I could only talk about it and not prove it. Then I got myself a stock Datsun with an unmodified L28 and thought, "I'm gonna document every change I make to this engine and dyno it every time to see what my butt dyno feels!" So, I have a dyno sheet that shows the difference what headers and a nice exhaust make to the L series. The original exhaust manifold and 1.75 inch was replaced by a set of HM39 (Aussie brand) and a 2.5 inch exhaust with two mufflers. I don't want to shoot my own argument down here by saying that the discussion only involves headers and not the rest of the exhaust but I kinda see it as a whole package really. If you didn't want to upgrade the whole pipe and muffler shebang your power gains probably won't be as much as mine. Still worthwhile?.......absolutely. :laugh:

This is your 'other modifications'. You don't have to start elsewhere, you can start with the exhaust system if you like. On all of my Datsuns that I've modified over the years, the exhaust system was often where I started my mods. I was never left asking myself "if that cam had a better exhaust I wonder how it would go?" I believe that there is some performance gain to be had by adding a header. If you were to use one like in the picture, then I have even less doubt since its a tuned length version. The stock manifold is not and this alone will alter the 'feel' of the engine ie moving the torque band/ power curve around to different rpm levels. What often happens is a modification is made without attending to any of the other engines' systems ie ignition/camshaft timing and carburettor jetting. The results obtained from just swapping parts isn't the whole answer to the performance question. Your engine will need some tuning if you want to get as much as you can from your (new) combo. Hey, isn't that the reason why we change parts on our cars, for love of tuning! Do it man, put those headers on, you know you want to.......

Yeah, our combo's are similar. In Australia, we never got either the P90 or P79 L28 heads. We only ever saw the N42 head and as such the gasket is for an N42 head. What I used was a genuine Nissan gasket made by Nissan. There were some Nissan HG's sold here that were made by local manufactures but sold by Nissan as genuine. Funnily, they still have the stamps of the other manufacturer on them. :stupid: PS More pictures of your engine please Guy!

Great stuff mate! Lookin' good......

Lat 33 deg 46 min south Long 150 deg 55.9 east Yes, isn't it lucky we don't live on a planet like Jupiter....imagine postage costs!

True, you wouldn't need to shave the N47 but it has 42mm inlet valves. The exhausts are the same size and the ports both have liners. A suitable alternative with minimal work. I don't have a P79 at home but I do have an N47........thanks mate for reminding us of a suitable option

Ooooops, yes I do remember now that you mention it....I'm gettin old mate :stupid: Yes it's a lovely engine concept, I completely endorse it The P79 has a nicer more modern chamber shape and what you've done to it, it'll sing. A 2.4 L capacity with a 280 head et al equals awesome!