So another full day of dyno testing yesterday. Warmed up motor, base lined at 684 corrected hp for day. Theres not much temp/baro compensating turned on in efi program right now so not unusual to see power change 1% day to day.
So we made global changes to fuel pressure, simply wanted to see IF power output changed w more or less, if it DID our tune was still not perfect. This applys to ANY basic efi too, if giving it more or less fuel changes it measurably then yourbnot there yet!
So, we go from 42.5 to 47.5, motor losses another 10-15 ft lbs tq from 2800 to 4000, picks up 5 ft lbs at 4200, 11 at 4400, 17 at 4600 , similar gains of 3 to 10 hp all the way to peak. NOW, some of it only got us to barely beatour good numbets from last dyno session, keep in mind again most the temp/baro compensating stuff in this tune isnt set up yet. So, we reduce fuel pressure down to 37.5, pull, motor cleans up from 2800 to 4000, definately is down from there up so i cut pull short. So i make some quick changes to tune taking fuel out down low and adding 3-4% in the midrange, 1% on top, ive previuosly added dubtracted that 1% and hp bounces between 684 to 691 corrected depending on day so your really just chasing a ghost at thst point.

So after making changes make pulls to verify, DEFINATELY picked up so.e of that missing low tq vs best carbed pull, definately fattened up tq peak range, saw 686 hp peak.
So now we add another 1" spacer, stuff gets real interesting, we already have a phenolic 1"4 hole inder tb, now we have THAT and 1" open.
Make pulls, motor picks up EVERYWHERE, 5ftlbs 3400, 7 at 3800, 2 at 4400, 7 at 4800, 5 at 5400, hp peak really widens up, +7 at 5800, 10 at 6000, make 690 to 692 from 6300 to 6600. Afrs: they barely change. Tq dip at 4000, does NOT change.
So, WITH some fuel tweaking, then adding a second spacer we have now matched or beat the best carbed muffled vs muffled pulls. Im surprised w the extra spacer motor lost nothing anywhere, it only gained!

So now we make a glory pull, no mufflers, just open headers. I did this last time too, it fattened up tq but hp went knowhere. Not this time, w open headers we hit 695 hp at 6500, 705 at 6700. The tq from 4000 to 4600 went up 25 to 30 ft lbs, the spacer seemed to really help with open headers but pretty irrelevant since running w the mufflers is much closer to what boat exhaust would be like

So now, we move on to rons tb. 102 mm chinese copy of a fast, mounted on a elbow. We thought it was 105, its not, when norm tested it it flowed sub 900 cfm, after grinding and tweaking still did not break 1100, no where near the 1600 or "2000"we thought it flowed although keep this in mind too, its a single mono blade, very few flow benches including norms can flow a 1000 or 1500 cfm at normal pressure, you would need a 10 or 15 hp air pump on the bench. So when you do something this big it has to be done at a reduced air pressure then calculated back so you can start losing accuracy.

good luck,,we'll be waiting on the results.
btw,,good job

So ching chong tb on, added the 1"spacer right off the bat, make pulls. AFTER changing fuel to get afrs right it
Pretty much whacked 0 to 20 ft lbs of tq and 14 to 26 hp off from 5400 up, at 6500 hp was down 48 before tuning and 23 after tuning. At 6000 was down 20 even after tuning. No where did we pick up tq from its smaller size.
Torque dip, with its crappy compression and huge cam, this motor has a 35 to 40 ft lb tq dip around 4000 rpms, with carb, w 4500 tb, w and wo spacers and even with the much smaller monoblade.

I bet your neighbors luv the open header pulls............lol.........I would....

So ching chong tb on, added the 1"spacer right off the bat, make pulls. AFTER changing fuel to get afrs right it
Pretty much whacked 0 to 20 ft lbs of tq and 14 to 26 hp off from 5400 up, at 6500 hp was down 48 before tuning and 23 after tuning. At 6000 was down 20 even after tuning. No where did we pick up tq from its smaller size. Tq at peak was down from lows 630s to 610 ish, a solid 20. I sorta thought somewhere the motor would pickup some tq. Another strange thing is we monitored map pressure/vacuum st wot, i never saw map drop below 98.8 at wot which tells you its not really a restriction BUT if that was so why the hp drop then? Previously when dynoing 502 mag i saw all kinds of map readings down between 92.5 and mid 90s when trying restrictive tb's, fallflame arrestors etc.
Torque dip, with its crappy compression and huge cam, this motor has a 35 to 40 ft lb tq dip around 4000 rpms, with carb, w 4500 tb, w and wo spacers and even with the much smaller monoblade.

Luckily we are zoned light commercial/ag and they are 1/2 mile away. I try to only make 1 open header pull a day though as it carrys along ways! Last time i dynoed with mufflers on Norm who lives 4 and 1/2 miles away called me up and said i could hear you off in the distance!

What do you run for dyno muffler? Thanks