350 TBI tows 5000/6000lbs

[donforeman]

OK Thank you for the input. I stopped pushing the van when it hit 220, it went from 170 to 220 in maybe 6 miles. I was afraid if I didn't back off and let it cool, it would have just kept climbing. My autometer trans gauge only goes to 250. I will keep the radiator cooler and try and fit a bigger trans cooler in the van. The factory one is pretty big. Its 11"x6" but looks pretty thin thickness wise.

[Brian P]

You really, really need to organize it so that the torque converter stays locked in direct and in overdrive. If the shift sequence won't allow that, but will allow lockup in direct drive when manually shifted, manually shift to direct drive (D3) whenever you start going uphill and you detect the torque converter unlock.

[donforeman]

Thanks for the input. I always tow in third. The 4l60e has a very short life expectancy if you tow in OD.
Its a learning curve. I was lucky enough to get the advice of Billy from another forum, he was a GM trans calibration person. He has helped with a lot of good advice. Here is what he said when I specifically asked about locking the converter really early in 2nd on a 4l60e trans.

The strategy is solid. But it's an L60. Keep this key point in mind. The L60 has low pump flow at lower rpm ranges coupled with when the Converter is locked or On, the oil flow in 3rd and 4th flows easily to the converter and starves the 3-4 clutch pack. As GM Stated in the owners manual to tow in 3rd gear. So locking the converter in an L60/65/70 I would hold to this. No one outside gm has this knowledge that I know of. Personally I would only lock TCC in 2nd at WOT. We ran extensive tests and found 0-60, 30-60 and more the times to obtain the upper spd is reduced or it's faster. A large benefit is it reduces heat generated by the slip. This slip across the converter is only heat generated without any gain.

GM with the factory chip did not lock the converter until really high speeds. The comparison bin, is from a 3.73/4.11 truck trans table, so they knew the engine would be spinning up there at those speeds. If you look at the factory table they did not lock the converter over 57% until 75. Probably for the reasons Billy told me about. Here is my current trans locking table on the right. Note I did lock the converter in 2nd as Billy directed, but also dropped the lockup speed a lot in 3rd and 4th. Something he did not recommend doing as it starves the 3/4 clutch pack. I did it as it builds heat fast with the converter unlocked, so its kind of messed up either way. I could drop the lockup 5 mph more and keep it locked on the hills but I have no idea how badly I am starving the clutches. Pulling this kind of weight I will probably shorten its life a lot. Most likely I will need to go to a 4l80e in the future, but just trying to get by as I rebuilt the 4l60e two years ago with towing upgrades. I have no idea why GM thought it was a good idea to put a 4l60e in a G30 van, even if it was the 7400 GVW version.

[Brian P]

55 mph in direct drive will be about the same engine (and pump) RPM as the factory lock-up at 40 mph in 4th. If that's enough pump RPM to hold the 3-4 clutch engaged in 4th, it ought to be enough in 3rd ...

The factory calibration probably avoids lock-up in 3rd at least in part to avoid customer complaints about harsh shifting. It would normally leave it unlocked accelerating through 3rd so that it is unlocked at the moment of shifting to 4th, and then there will be a delay before it actually locks up in 4th. Unlocking it in 4th the moment the driver breathes on the accelerator pedal allows that to be done without a big jolt, too. Personally I would be okay with the more direct feeling of having it locked up, even if it means feeling the gear changes (and locking and unlocking).

Does it drive okay with how you have it set up now?

[In-Tech]

Sheesh, I don't know what software you are using and it doesn't matter. The left side is percentage tps. You are about to kill that trans. There are many balances needed in auto trans electronic functions. I hope you have fixed the upshift/downshift stuff too. I hope I am not sounding too brash. The transmission tuning can take as much or more tuning as the engine. Just warning that it all has to work together and you can't change one table at a time. All of these tables work together and I see it all the time where "tuners" don't know you have to make all of the tables work together and they kill stuff.

An efi engine is dumb, it only knows what you tell it. It can make some adjustments just like the transient logic in the trans controller. Fuel and spark allowed adjustments are not near how you can kill a trans.

[donforeman]

Sheesh, I don't know what software you are using and it doesn't matter. The left side is percentage tps. You are about to kill that trans. There are many balances needed in auto trans electronic functions. I hope you have fixed the upshift/downshift stuff too. I hope I am not sounding too brash. The transmission tuning can take as much or more tuning as the engine. Just warning that it all has to work together and you can't change one table at a time. All of these tables work together and I see it all the time where "tuners" don't know you have to make all of the tables work together and they kill stuff.

An efi engine is dumb, it only knows what you tell it. It can make some adjustments just like the transient logic in the trans controller. Fuel and spark allowed adjustments are not near how you can kill a trans.

No you dont sound brash, you sound, uneducated. I showed you a table of the tunerproRT converter lockup points and you started off about shift points being wrong? You cant see the shift points. Skip the lecture about working together when you haven't seen the rest of the tune. I have a chassis dyno business and see bad tunes all the time, so thats a fact but I show you one part and you get all of that out of it? Dont get me wrong positive criticism is good, but you started off on a tangent that you have no clue on.

[donforeman]

55 mph in direct drive will be about the same engine (and pump) RPM as the factory lock-up at 40 mph in 4th. If that's enough pump RPM to hold the 3-4 clutch engaged in 4th, it ought to be enough in 3rd ...

The factory calibration probably avoids lock-up in 3rd at least in part to avoid customer complaints about harsh shifting. It would normally leave it unlocked accelerating through 3rd so that it is unlocked at the moment of shifting to 4th, and then there will be a delay before it actually locks up in 4th. Unlocking it in 4th the moment the driver breathes on the accelerator pedal allows that to be done without a big jolt, too. Personally I would be okay with the more direct feeling of having it locked up, even if it means feeling the gear changes (and locking and unlocking).

Does it drive okay with how you have it set up now?

It drives excellent. I lowered the lockup points to help with the heat and it did that some but once you get on a steep grade with the converter unlocked it still rises so a larger cooler is in order. I may raise them back up once a larger cooler is installed just so I dont have any chance of starving the 3/4 clutch under load. There is a scalar that unlocks the converter temporarily under shifting anyway you just cant see it in this table.

[In-Tech]

Fair enough. This is why I hate typing stuff, sometimes it is taken the wrong way.

[donforeman]

Fair enough. This is why I hate typing stuff, sometimes it is taken the wrong way.

No sweat, I must have taken it wrong. There are a lot of bad tunes out there. Most of what you said could be applied generally, but I do take a lot of time with mine so that's why I was like what the hell? I am pushing the lockup points but its mine, not a customers. If it goes it will get the 4l80e.

[donforeman]

I did get 10.039 miles per gallon on the trip, pulling the enclosed trailer, chassis dyno and support gear up the mountains on the two lane back roads. So the people asking about mpg with ramjet cam and vortec heads a few pages back. Once its tuned properly, I do not think its any worse than a stock tbi engine. This is with the 4.10 rear axle ratio, in 3rd and 2nd on some of the steep stuff. Unloaded in 4th on the freeway it would probably do much better.

[donforeman]

I messed around with putting the van on the dyno today. Pretty close to the same numbers six months later. If you want dynojet numbers multiply by about 1.10. All runs were with a locked converter and locked in 3rd to eliminate that variable. The ramp rate was slowed down. I wanted to have plenty of time to get a/f readings and the long slow pull is pretty much what happens every time the van hits a hill towing the dyno. The engine is stock, except for the vortec heads, 196 ramjet roller cam and a nice ss exhaust.
181 peak was a base line run, I had a few of these runs all within about a hp.
178 Peak was when I multiplied the last three rows of timing numbers in the table by 1.05 and re burned the chip. Yes it lost power! Timing is really close to the stock vortec table listed on gearhead-efi somewhere. This mirrors what happened last time when a tried to increase timing for WOT runs. I do think there is a little to be had at part throttle still, but I will save that for another day. No knock retard except for one table cell and that was usually less than 1 degree.
184.5 peak was when I pulled off the air cleaner and ring and let cool to 166. You will see a noticeable jump in the mid range, bigger than the peak numbers. I kept the ring and air filter off for the rest of the tests. Its the ring that is stock to the TBI that looks like it may be the restriction point.
182.8 and 182.6 peaks runs were run hotter to see if the temp was the reason for the hp jump. Just lost a hp or two for the 10 degree jump in engine temp. The run that started late was just that. The sun was on the screen and I was like oh I can go now. Its not a race car. Most of today's work allowed me to pull a little bit of fuel out of the upper transition areas for even better mileage. The hp runs were just a curiosity check and then I had to mess with a few things to see if I can improve. I think the Jegs power bowl that replaces the factory ring or what ever they are calling it may have some interest next but its pricey for what it is. It already has a 14x3 summit filter.

[Carnut1]

Without rereading the thread, are you running the stock throttle body? They feed air from the sides which is what that bowl does. Mill off the stock lip and give the edge a nice roll. Add two gaskets under the injectors to get them out of the air stream. Tbi needs all the airflow help they can get! Thanks, Charlie

[donforeman]

Yes Stock throttle body. The heads, and tiny roller cam are pretty much the only real changes. The manifold is chevy's adapter manifold, but I really don't count that as I don't think the design is much better than the original. Its just used because of the head pattern.

[GARY C]

Without rereading the thread, are you running the stock throttle body? They feed air from the sides which is what that bowl does. Mill off the stock lip and give the edge a nice roll. Add two gaskets under the injectors to get them out of the air stream. Tbi needs all the airflow help they can get! Thanks, Charlie

They make spacer for that. https://www.jegs.com/i/JEGS/555/15410/1 ... &gclsrc=ds

[donforeman]

Thanks for the tips from all. I probably should have put the pressure sensor and logged the vacuum. I can see from the logging that the map goes from the 100kpa row over to the 90 kpa at the very last part of the run. I didnt think it was that bad though. If its a CFM issue, just thinking out loud, why was the biggest gains at lower rpm? I was guessing that the lack of the factory spacer let the air flow more evenly from all directions, possibly making a better fuel pattern instead of a cfm issue. This is my first TBI truck so maybe I am way off base.