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Discussion Starter · #1 ·
Im working on a 3.1L f54 buildup to replace my existing '78 L28 and don't know which way to go with the fuel delivery/management.Should I just bail on the EFI and go with carbs or go with bigger injectors and aftermarket EFI? This will be primarily a street car with occassional strip use.

Any suggestions or references would be greatly appreciated.
 

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<b>RE: Anyone running a 3.1L EFI?</b>

As it stands now I personally know 4 guys running 3.1L and not one of them is running FI. They are all running Webers except for one guy running Mikunis. I personally run 45mm Webers though I'm using them on a highly modified 2.9L. I too have recently started to question the idea for FI but I'm worried about the flow. If you open the throttle plates on my 45's you can actually see the valve stems in the head! I also heard here I think that the turbo intake manifold are 17% larger than the N/A manifolds. I would like to get a measurement on those runners to get some idea of flow.
If you happen to find out more info please post it back here for all of us to learn.
The Turbo Z's don't appear to be as worried about intakes as they just prepare the car for more boost to get more power.(not to insult turbo cars)
I've done about all I can do to my motor without spending another 5-10G's for only a little more hp. I'm already at 10G's for my entire engine.
Good Luck in your search.

ZR8ED.
 

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<b>Use the Z FI - No prob!</b>

No prob. Just use the 280Z or ZX FI. Reccomend using a 'big throat' style t/b. Just bump the fuel press (use an adj reg) to 42-52 psi and twist the afm about 14-16 notches tighter. Play with both and it will come together. 225+hp w/o headers, perfect drivability and 25+ mpg are possible.

Rcr X
 

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RE: turbo manifold is not any bigger

ZR8ED wrote:
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I also heard here I think that the turbo intake manifold are 17% larger than the N/A manifolds. I would like to get a measurement on those runners to get some idea of flow.
If you happen to find out more info please post it back here for all of us to learn.


I think that rumor started in Steve Webb's article on his "stealth" Z. There is no truth to that. The turbo manifold has the same size runners as any other manifold. I've actually went down and talked to Steve about this when I was planning my own buildup. He agreed and said he made a mistake when he wrote that article. Somebody needs to go back and edit it.
greg
71 240z
 

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<b>RE: turbo manifold is not any bigger</b>

I'll stop by the shop tomorrow and measure a manifold up and post some exact numbers.
Thanks for helping out everyone. The more comments the more accurate of a picture I can get on this possibility. I'm in no hurry cause I'm going to run with my Webers for this season so I can get some official stats on the engine. (plus a few scores to settle. hehehe) I have all winter for an actual conversion.
Thanks for the info!
Keep it rolling in please.
ZR8ED.
 

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RE: turbo manifold is not any bigger

Throttle body/opening or runners? The throttle body to begin with is substantially larger than any of the NA TBs. I haven't actually measured the runners, but I to have heard from a friend(not stealth) that they are in fact larger. I am almost certain that hey had two intake manifolds side by side and measured them. Also, has anyone checked out what the flow characteristics of the different intake manifolds are? I know Nissan did a lot of R&D on that engine.
Later,
Tim Deesen
71' 240ZT
 

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Discussion Starter · #7 ·
RE: Use the Z FI - No prob!

I do have the big throat throttle body but what about the stock ECU? Will it need to be modified or will it adapt to the added flow? Also, How do you twist the AFM tighter?
Thanks for the help!
 

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<b>RE: Use the Z FI - No prob!</b>

Stock ecu is fine. On the afm, carefully pull the black plastic cover off of the side of the unit. You will see a large round plastic 'gear' inside. On the left side of this 'gear' will be a phillips screw and a small tab. MARK the position of the gear before loosening the tab!!! Loosen the tab and move the gear in the direction of tension (like winding a spring). About 12-16 'teeth' or notches is usually sufficient with fuel pressure in the 48psi range.
 
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