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84 K20 "Ethel" Not an Sbc/NV4500/241C

Semi restoration of a 1984 K20 pickup. 5.3 LS, nv4500, np241c.
This is well over my head I'm afraid to admit, I haven't even figured out how to tune my fitech yet....
Me too.. but I figure I hasnt blowed it up yet.. and the mfr was brave enough to swing the cam back and forth way more than I am..
 
Me too.. but I figure I hasnt blowed it up yet.. and the mfr was brave enough to swing the cam back and forth way more than I am..
Mfr short for emeffer? lol supposedly it's easy to tune but it has to run first. It'll get there just as sure you'll get yours. Perseverance pays so they say
 
As promised here is screenshots of the stock vvt table (there are 3 this is the low baro)
View attachment 248730

And here is the adjusted table, if you notice there is a huge amount of retard in the lower cyl airmass and rpm areas, then they basically start to roll the cam back at 3500, I dont fully understand the dynamics at play here but the seat of the pants dyno says in that specific zone its snappier. It also sounds smoother and more... organic?? if that makes any sense? It doesnt sound like it kind did before when the engine at cruise sounded a little unhappy lol..



View attachment 248731
Here is a log from today, this would be around 80 mph uphill and it was pretty warm.
View attachment 248732
That damn low end EGR retard. I wonder if that's still enabled on my 6.2. I have some weird behavior at low end OD hill pulls.

With the steep ramp you set at about 2500rpm, do you notice a sudden jump in engine power? Like VTEC just kicked in yo!

Nice work on the tune though, nice flat lines.
 
That damn low end EGR retard. I wonder if that's still enabled on my 6.2. I have some weird behavior at low end OD hill pulls.

With the steep ramp you set at about 2500rpm, do you notice a sudden jump in engine power? Like VTEC just kicked in yo!

Nice work on the tune though, nice flat lines.
I bet ya that is what you are feeling, on the hp tuners forum that’s actually the engine they referred to with these cam timing numbers.
Funny thing with that jump it actually has a noticeable transition but there isn’t a drop off in torque. I am gonna smooth it out some and see how it feels.. I am just totally shocked aside spark this has to be the single largest butt dyno improvement..

And thanks this is my first go round with any gm efi.. I am a carb guy lol
 
Ok checked mileage this morning, 14.5mpg, includes tuning, hooning, and commuting! All in open loop :) so I would imagine if I was conservatives it would get better.
I also sloped the cam table and it seems happier.
 
Alright double checked the fuel mileage for the round trip work commute, 6.66 gallons for 100 miles.. I’ll take it!
Also with the cam timing sloped it doesn’t actually get into that region crusing so I can now maintain 80 uphill in OD without pushing it past 1/2 throttle..
 
Stock arm located from local buddy and now installed, we’ll see if this fixes my bump steer issues
 
After rereading through your LS swap/NV4500 adventure, it’s clear you made the best decision for Ethel. Lots of great info, and appreciate your detailed documentation.

David
 
After rereading through your LS swap/NV4500 adventure, it’s clear you made the best decision for Ethel. Lots of great info, and appreciate your detailed documentation.

David
Thanks David!
I am really trying to keep the nonsense to a minimum mainly because I had so much trouble findin certain details when building it. If it helps someone on here then it was worth the time. It also helps me catch errors and is sort of a log of the changes. I hope to continue this when I get Lucy back home..
 
So far no huge probs, I have been tweaking the timing to get rid of some high load low rpm knock, and I also think the tail shaft bushing is shot because I have some decent vibes.. also got most of the parts to quiet her down some, I must be getting old but quieter would be nice right about now on a near hour long drive every morning and night. Lol
 

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