6-1 header leaning out my stock EFI - Nissan : Datsun ZCar forum :Nissan Z Forum: 240Z to 370Z
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post #1 of 5 (permalink) Old 11-02-2019, 02:49 PM Thread Starter
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6-1 header leaning out my stock EFI

Switched out to an MSA coated 6-1 header last year or so from the MSA 3-2 as I liked the sound and the look of it. Then buyers remorse started kicking in. By my butt dyno I am making less torque and have to rev higher than the 3-2 did for my normal driving. I put new plugs in and its definitely leaner that the 3-2 by the readings. The one that gets me is plug 2 looks a lot like 6 as it is common for 6 to be lean on a 280 with oem EFI. 6 looked like it was brand new so it is a little lean for my taste. The coated header no longer shines its definitely burned off some of the coating.

1. Put the other header back on and drive it. Cheap and relatively easy fix.
2. 280ZXT injectors, Cheap and relatively easy fix have to retune what I can.
3. Gut fuel system and install carbs.Or Megasquirt with bigger injectors. I have round tops ready to rebuild with 260z intake manifold. Cheapest and easiest on this choice but more expensive than the header. Megasquirt has a higher entry price plus some dyno time.


Thoughts?



I decided to go to an older set of plugs NGK BPR5EY, I took a chance on these BPR5EIX-11 IX Iridium Plugs. Drove 15 miles and there is a difference in copper and iridium, much more torque. Now to read them after a few tanks of 93.


Thanks!

1975 280Z F54/N47 MSA 6-1 Header 2.5 Exhaust

Last edited by bificus; 11-02-2019 at 05:42 PM. Reason: Went to a older copper plug.
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post #2 of 5 (permalink) Old 11-03-2019, 03:13 PM Thread Starter
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[email protected]#$ one of these BPR5EY plugs are bad... Misfires over 4 k. Now to my back up back up plugs. BPR6ES-11

1975 280Z F54/N47 MSA 6-1 Header 2.5 Exhaust
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post #3 of 5 (permalink) Old 11-07-2019, 02:11 PM
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Originally Posted by bificus View Post
[email protected]#$ one of these BPR5EY plugs are bad... Misfires over 4 k. Now to my back up back up plugs. BPR6ES-11
First of all, maybe your butt dyno needs to be recalibrated, maybe yes, maybe no. Time has a way of fooling a BD, it's called getting acclimated to a condition. Going to bigger injectors on a stock engine is a bad decision. Throwing a lot more fuel at an engine doesn't necessarily give you more hp, it usually creates the opposite effect and reduces the fuel economy. If it's running too lean, then richen the mixture up a little. If 1 or 2 cylinders appear to be burning differently on the plugs then check the injectors on those cylinders, ck the injector connectors as well, ck the secondary ignition on those cylinders, and possibly even the valve adjust. Has the head been rebuilt on it? The plugs that should be in your engine are the BP6ES but you can also use the BP6ES-11 if you prefer. The 6-1 header is a tuned header and is definitely more efficient for your Z versus the 621 model. You're referring to having to drive it at a higher rpm with the 6-1 header, but what rpm's are you actually doing? The power curve on your engine is 3000-5500 rpm. Below 3K it's going to be sluggish no matter which header you're using. What exhaust are you running with your header? Do you have a performance cam in it, or a stock one? These are all important factors and are all related. Z man of Washington

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post #4 of 5 (permalink) Old 11-07-2019, 02:29 PM Thread Starter
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2.5 exhaust similar to the 2.5 inch I had with the 3-2 header. 280zx distributor. Everything else is stock. The plugs are what I see are a much lighter tan than the 3-2 and #6 is white. So I am going to run these plugs for a couple of tanks and read them again. Probably needs a valve adjust, head is an n47 so not sure when it was gone through last.
Thanks for replying ZMOW

1975 280Z F54/N47 MSA 6-1 Header 2.5 Exhaust

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post #5 of 5 (permalink) Old Today, 12:50 PM Thread Starter
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Running BG44k in it this weekend.
Checked injectors for clicking - OK
Checked resistance 3-3.3 ohms -? (shitty meter but readings are close.)

1975 280Z F54/N47 MSA 6-1 Header 2.5 Exhaust

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