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454 low end torque is weak

I keep thinking about this torque converter, it was advertised as an "allison spec low stall". Does anybody know what this converter is rated for stall rpm. It feels pretty tight (need more brake pressure when idling in low range).

I have had 3 motors in front of it now,
mild 6.5td must have been a good match, because I never even noticed the converter.
stock tbi 350, was an absolute turd
and now this 454

maybe I will throw a stock converter in and give it a try.
 
Just went and power braked it. With no movement or wheelspin, I can get 2100 out of it. seems like plenty of converter.

I suppose I will have to go after the tuning (as suggested) when I get some time.
 
I didn't think about torque converters before, but I also run an RV/towing converter that is supposed to get closer to a full lockup on the Th-400 and the stall speed may be a bit lower than stock. My uncle said it was as close to the Allison for strength, as you could get for a th-400. I haven't driven anything with a higher stall, especially in a truck.

My 88 K5 feels like it might have a higher stall than stock. It doesn't creep on it's own when I let off the brake. My uncle built the trans (owns a trans shop) and said that some vehicles have multiple torque converters that were used depending on vehicle options.

Let us know how your tuning goes.
 
Not sure if its been mentioned, as I'm on my telly reading this. But have you gave your tire size vs gear ratio a thought? It won't bark 40s with 3.73s. Just a thought. Sorry if its been mentioned.
 
454Sub said:
Not sure if its been mentioned, as I'm on my telly reading this. But have you gave your tire size vs gear ratio a thought? It won't bark 40s with 3.73s. Just a thought. Sorry if its been mentioned.
Click to expand...

235/85-16

And I am not concerned about not being able to burn out, I just figured that it should be able to, and fairly easily.

my main complaint about the thing is,that it is pretty sluggish from a start with a loaded trailer. trailer weight is usually 7-8k, but have pulled as much as 9k. I really want to get the lower gears for the th400, but I think what I have should work better than it does.
 
Stock 7.4l spark advance is horribly conservative.

Did you set it to 4 degrees (actual 3.87) advance with bypass wire disconnected? If so add 5 more but only for a test drive and not WOT high RPM and see how much difference it makes.
 
It has been awhile since I played with the timing, but I am pretty sure I have it set at 6, because it was pretty weak at 4. And yes with wire disconnected.
The tuning in this chip pretty much sucks. It has enough timing idiling that in runs rough, and hard to get a low idle. It pulls harder yet with the timing at 8, But if you take off with a load and light throttle, it will miss during the time you are just moving from a stop. If I had the time I would like to just leave the thing with you and get the tuning done right

Is it possible to make this a closed loop idle? End up doing a lot of drastic elevation changes and it spends some time idiling, and it seems like it burns more fuel than it should during these times.
 
Do to IAC logic it is impossible to get a low correct idle unless in gear. Will always be higher in P/N. Manual trans chips are better as the ECM thinks it's always in gear so IAC has full logic for idle.

Reason your seeing the miss when timing is advanced and light throttle is GM forgot vacuum advance (in chip) in most 7.4l but it is in 5.7L, just look at the timing tables. That miss should go away after 1000 RPM...

Yes you can get Closed Loop Idle, and DFCO, and DE, and Lean Cruise, and drivability and even some MPG but they are still a pig towing.

Using a good aftermarket TBI adapter (thick aluminum) on your aftermarket intake and centering the bores helps balance fuel to all cylinders. Read your plugs! Rear will be richer then front. The stock TBI adapter that came on them was because the same engine was used in HD trucks with a carb, so they could use one engine. Later years had a TBI intake.

Cam and intake change is probably more the cause of your issue and fueling table needs to be corrected as well as AE for the intake. 3000 RPM up seems good because there's not much vacuum, just dumping fuel from the max end. This is why dyno tune WOT is fairly easy, it's the drivability and idle which are time consuming.
 
Maybe this was a bad way to do this, but I cut the p/n wire so the ecm always thinks it is in gear. This gave me a low idle when in p/n.

And I have yet to get a speed sensor put into this np205, so I am sure that will help out.

Also, I do have one of the later tbi intakes, do you think I would be better off with it?
 
When things are set right like timing and minimum air setting of throttle blades the idle in P/N is not that bad and hardly noticable without a tach, few hundred RPM higher but no real stratagy, just a high and low and it's somewhere in middle, helps warm up. IAC quickly sees going to D and compensates for the bang into gear, works quite well.

VSS helps idle more then anything on these. Also neccesery for TCC, DFCO DE and Lean Cruise. Everyone I have ever done without VSS was better with VSS. Even driving!

Not sure about an intake change? Never tested. But the adapter I have and it's a lot easier...

In the end even a stock 7.4L engine can be made lots better, more so with engine mods. I think emmissions were more leanent on HD trucks so GM just made the chip safe, not efficient.

Also most of the chips for 7.4L have no knock retard? Even in trucks that had a knock sensor? Many don't. Haven't figured out what they were thinking here?
 
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