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Put the Accufab on first, I bet you feel an amazing difference even with stock exhaust manifolds, then put the headers on, and see if you feel even more difference, or not.
# NOTE: TESTING WAS PERFORMED IN UPSTATE NY. AMBIENT TEMP 70~80 *F, 50% RH, 1,100 FT ABOVE SEA LEVEL
Initial Observation:
1) Regular driving is greatly improved. It does allow more air to the motor before triggering a downshift via throttle position which makes it feel like you gained a lot of power. Really, this is allowing the engine to lug more, same as if the shift points were moved up while retaining the stock TB.
2) When doing a converter stall test, the engine can achieve a bit higher stall which develops a bit more torque.
3) I only have two sample recordings for stock and two for ACCUFAB. Within those sets is 3 or 4 0MPH to 50MPH runs (This big old girl is too damn slow to get to 60 on the windy backroads) and at least one stall test. Let the numbers speak for themselves.
My takeaway: Part throttle power is greatly increased because part throttle airflow is now greatly increased. Perfect for daily driving, highway cruising, and towing while avoiding unnecessary downshifts. Peak power though? No real improvement.
But seriously, with how the truck handles with just that one modification, isn't that how the V10 should have been all along, from the start? The power, the response, the drivability?
I would agree that 99% of the time, on most other vehicles, a TB swap does next to nothing, but the V10 is that 1% that it does a lot.
And here is the last updated chart of the numbers we came up with thus far, you can compare them to your numbers.
4) The idle is lower and now perfect. Before it was idling over 800 in neutral and trying to maintain 700~750 in gear. Just too high and had to stand on the brakes pretty good to remain stopped. Now the neutral idle is ~750 and in gear idle is 600 which is just perfect. Smooth, easy stopping, quiet, and doesn't feel/sound like it trying to get away.
4) The idle is lower and now perfect. Before it was idling over 800 in neutral and trying to maintain 700~750 in gear. Just too high and had to stand on the brakes pretty good to remain stopped. Now the neutral idle is ~750 and in gear idle is 600 which is just perfect. Smooth, easy stopping, quiet, and doesn't feel/sound like it trying to get away.
Well that just goes along with Accufab being a lot more precise and refined at how they make the throttle bodies than Ford, you can see the difference in the build quality, 1 is a casting, good but not excellent quality, versus the Accufab which is super precisely CNC Machined from Billet. I also noticved the smoother idle, but I modify my idle settings so I figured my adjustments might have also contributed.
Um, if the engine isn't flowing more air/ making more HP at WOT with the new throttle body then it did with the stock throttle body, then the stock throttle body is not a restriction (maybe that could change after the headers are installed).
Yes it'll let more air past at the same % open ( because its bigger) but if you want the amount of amount of airflow given by the bigger throttle body at 50% open, then open the stock throttle body 60% and you'd have the same air flow.
The transmission shift points can be adjusted so it takes a higher TPS percentage number ( find a shop that uses HP tuners or EFI live or a whatever tuning software you prefer) if you want the engine to be flowing more air/ making more power before the transmission shifts under part throttle driving.
The chart is post #5 above tells me the stock throttle body is fine. And smaller throttle body blades have a more liner airflow rise vs. percent open compared to larger ones, which would make the throttle pedal less touchy coming off idle (which would be useful for things like backing up a trailer).
I'd be interested to see stock throttle body and new throttle body data after the header install as maybe then engine will be moving enough air for the stock throttle body to become a restriction, but with an otherwise stock engine, that new throttle body isn't doing anything that couldn't be done by adjusting TPS % number.
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True... BUT, this allows so much more torque to be developed and delivered to the wheels before initiating downshifts. I agree with masterx, it greatly improves the drive-ability and honestly, it now has the grunt I was expecting it have.
New engines with Fly By Wire do this now too. Your gas peddle is a torque request. New engines will open the throttle body until 0.0 MAP is achieved and then it will initiate a downshift for more torque.
Also, a stock chevy 5.3L comes with a 86mm throttle body and the 6.2L a 92mm throttle body. Then these 6.8L V10s only come with two 50mm throttle bodies which only equal to a single 70mm throttle body!
@Anton , you are failing to see the throttle geometry factor, on our trucks there is a set point of throttle position that causes the trans to shift up as the pedal is pressed down. That point on the V10s does not coincide with the point of max torque, actually a noticable step away from it, you can play with shift points all you want, but you are still stuck with the same position on the pedal that will trigger the downshift to 3rd, etc. This throttle body effectively moves that extra torque potential to the usable side of that point, so its available before you trigger a downshift. You can alter what RPMs the shift point occur at, but that does not change the point in which the throttle will trigger a downshift, thus the throttle body still provides a power bonus.
Knock it all you want, but thus far, every single person who has "actually tried one" that i have seen, has liked it, and seen the gains in drivability, towing power, etc, even if they couldn't fully explain them.
Plus, some people say there is no peak gain, I still believe there is, and I can feel it in my truck, at WOT it definitely feels like its pulling harder at high RPM than it did before, and highway passing at 80+ also became much easier, which lends some credence to the statement, but I am also not running a stock motor..... I still want to dyno it, perhaps when life simmers down, and my prefered dyno shop went bust during covid.....XD, glad i got my tuning files for my GT all sorted before hand.
@kostkafex He shortened his cable using a cable stopper, i shortened mine with 3 zip ties, basically all that is needed is to tighten the cable slightly, he just decided to cut his and shorten it that way, my way is fully reversible, after 20 years my throttle cable like everyones was slightly stretched out already, and the accufab's throttle arm is just a tiny hair shorter, so if your cable has any stretch in it the pedal sags, you just gotta tighten it up a little, we used to have to do the same thing on the mustangs for the same reason, over the years the cable stretches.
Here is a video of how to tighten the cable using zip ties, the 94-04 Mustangs had cables prone to stretching over an inch over time, so you will see he has like 10 zip ties on his, it was baddd, however on our trucks, i only needed 3-4 to bring the pedal up to proper placement.
06-07-2022, 09:49 AM
