4l80e swap from a 4L60e PCM??

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racprops

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I THOUGHT I had this all laid out.

I have spent the past 3 years building a low RPM 383 for a high MPG engine for my 93 G20 Custom van, and plan on running a Motorhome 4L80e with a US Gear Dual range over drive to a stock 3.42 rear end.

AND That I could convert the two 8625s PCMs I have on hand as per the instructions in the doc.: Converting a V8 engine from TBI to MPFI using the 8625, 6395 or 7427 PCM, using the $E6, $0D, or $0E mask.

3 years ago I HAD found a tuner that said he could program a 8625 to operate a 4L80e with a eprom change, or some other reprogramming and he could also include a lean burn program such as the one in the Camaro PCMs.

Sadly I cannot reach him or find him. The virus delayed my work nearly the full three years. I lost track of some of the data.

I am trying to retrace my steps but not having much luck.

I found a tuner who does MPG tuning (VERY rare) but he is not the one, and saids:

“I believe I understood you correctly. I am saying that the 4L80E requires different solenoid activation than does the 4L60E. Not sure if these older ECMs have the ability to modify that or not (the LT1 PCMs do). That's what I'm checking with TunerCat about. I will check out the van calibration and see if the highway mode is available in it too (haven't worked with that one before).”

“Just heard back from him:

LT1 PCM Tuning

"No, as far as I know this PCM was never used with a 4L80E transmission. This would be a $E6 calibration. The 1993 heavy duty trucks that had the 4L80E transmission used the 16147060/16127470 PCM which is an $85 calibration."

” So it sounds like if you want to use your 4L80E then you'll need to use that '93 PCM that he references above, with the $85 definition file. I'm willing to help you tune that (via email) if you want/need it.”

So at this point I am totally lost, Looking at: https://www.thirdgen.org/forums/tbi/442325-notes-information-converting-tbi.html

And: TBI guys, its time to update! - Third Generation F-Body Message Boards with its 483 posts I am totally unable to comprehend it.

At this very hour I am leaning back to the idea of running one of the original TPI MAF PCM to run the fuel injection and running a 93 G30 PCM piggy backed to operate the 4L80e transmission.

So I am asking for a simple path to get this van running at its best, I am looking for a G20 Van getting from 20 to 30MPG.

I have the engine made to make torque from 1500RPMs, so it should pull easily, no lugging, I have the stock TPI system to feed it and with highway mode run lean for MPG, and I have the drive line gearing to run her at 1800RPMs at 80MPH.

Please help me get all of this together.

So I can find 16147060/16127470 PCM, and ones running 4L80e's but now I need instructions of converting them to run 8 injectors MPFI....

At this very hour I am leaning back to the idea of running one of the original TPI MAF PCM to run the fuel injection OR making the mods to my 8625s and running a 93 G30 4L80e PCM PCM piggy backed to operate the 4L80e transmission.


Thanks for your time.


Rich

racprops on third gen, (and here) which I discovered back in the mid 90s…when they discovered the Lean burn Setting…and that Camaros down under got 30/35MPG.
 

tayto

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run a 7427 and start with a 95/95 4L80E calibration. do not mess around with the 91-93 calibrations. not sure what year your ”motor home" 4L80E is, but the the earlier units can be converted fairly easily (new pcs solenoid and separator plate, will also need to drill a vent hole on the valve body). if it is a true motorhome trans, they are nothing special even if they have the straight cut planets. those planets are actually weaker (and noiser) than the regular ones. only needed for REALLY heavy rigs, they are not an "upgrade".
 

tayto

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also i will add the TPI system really shines in the 3000-3500 rpm range. a dual plane will make more low end power for the rpm range you are targetting. I am regurgitating information here, there is a poster on thirdgen & gearhead-efi "fast355" that has covered this stuff fairly well over the last 15+ years. i am planning on running a tpi setup in a friend's truck, but we were going to put 4.56s in and target 3000ish rpm while hauling his landscape trailer in 3rd to really take advantage of the TPI setup
 

racprops

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I have read about the questions over the Motorhome versions, and some do say they are stronger and others think other wise...I find it interesting that you point out they are stronger for "only needed for REALLY heavy rigs".....common response...seems they are stronger.

I have a 1989 Car Craft magazine article where they REALLY did a Tuneport showdown and on a special dyno where they saw the power curves from 2000 to 5000RPMs, very accurate: and the stock system made 296FtPd at 2000 and only peeked at 328 at 3000 that is only 32FtPds better and it then held to 3500 and started dropping to 5K.

The funny and sad thing was how much money it costed to improve that by only 30FtPds at 3500RPMs, HP was only slightly improved as well. It was NOT cost effective.

Everything I have read suggests other wise.

I am amazed by Fords 4.6 (under 289 CI) engines, very strong, I have owner three, and as I remember my 1998 Mustang and Cougar XR7, these 4.6s feel more like 5.7s and really have power from start to max...and they are running Ford's version of a TPI, just upside down in between the heads....Ford copied Chevy...a lot of money spent....I think for the same reasons GM did them, great torque.

I reached out to "fast355" and have not heard back.

Rich
 

tayto

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If you think they are something special and give you a warm and fuzzy, great. They're right up there with 5 pinion planets for the 4L60E IMO....


jakeshoe is the owner of Jake's Performance

Fast can be hard to get ahold of but I do believe he isn't BSing about TPI being only better in a certain range.
 
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L31MaxExpress

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$0E or $31 are the 4L80E operating systems for a 7427. $85 was the older 4L80E stuff. BNKM is a factory calibration for a 350/4L80E that works in a 7427 and works with the newer valve bodies. Personally the 165 MAF system is garbage. My friends TPI car we converted the 165 to MAP using Austrailian $12P from an 808 ECM. Code runs in the 165. Piggy backing ECMs is a waste of time. Might as well find a generic LS swap harness, repin the coils and injectors to the SBC firing order and use a Holley Vortec aluminum timing cover, Vortec distributor sans the cap and EFI Connection 24x reluctor with D585 LS coils. Use an 0411 to run the thing. I would add injector bungs to a dual plane manifold or find a dual plane MPFI marine manifold before using TPI. TPI will make less torque than a factory TBI system in the RPM range you are looking to run. Thorley once made tri-ys for these vans that built excellent low-midrange torque, now the best option is probably the 2.5" outlet Holley performance SBC manifolds, into dual 2.5" pipes and those pipes into a dual 2.5 to single 3" merge Y. Also Edelbrock had a MPFI conversion intake setup that kept the stock TBI unit as the throttle body. Those made a nice torque bump on a stock TBI engine.
 

L31MaxExpress

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Aiming to run 1,800 rpm @ 80 mph in a hightop roofed van is an exercise in futility. Just not enough rpm to make the HP needed to efficiently pull the thing into the wind. My mom has a 2019 Titan. The VK56 has always been a very torquey engine. Hers has all the latest gizmos. Variable valve timing, variable intake cam lift and duration, long runner manifolds, 11:1 static compression and direct injection. It has a 7spd transmission. It turns about 1,700 rpm at 70 in 7th gear. Going into a slight headwind or going up a grade it downshifts to 6th quite often. Nissan lowered the rear axle ratio in the NV vans compared to the Titan for a good reason. Titan has like a 3.36 gear and the NVs like a 3.70 gear.
 

racprops

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Thanks for your help.

From the evidence I have found A) they are fairly strong at 2K and B) I do not think anyone ever tested a TPI with a low RPM torque cam, all tests were with 85 to 90's Chevy Cams that peaked at 2800RPMs.

As for IF it will work check the following pictures out:

Note that is 350Ft Pds at 1000 RPMs
 

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L31MaxExpress

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Thanks for your help.

From the evidence I have found A) they are fairly strong at 2K and B) I do not think anyone ever tested a TPI with a low RPM torque cam, all tests were with 85 to 90's Chevy Cams that peaked at 2800RPMs.

As for IF it will work check the following pictures out:

Note that is 350Ft Pds at 1000 RPMs

My 383 with very accurate measurements on an advanced engine modeling software. I turn about 2,800 @ 70 and pull my 26' travel trailer in overdrive on flatter roads. Kickdown to 3rd puts me near 4,000 rpm and that 383 comes alive. I have still gotten 18 mpg out of the thing unloaded at 70-75 mph. When I still had the 350, 4L60E and 3.42s it got the same mileage in 3rd at nearly 3,000 rpm at 70 as it did in overdrive at 1,950 rpm. Even my low top van needed torque multiplication from gearing. When I swapped a 4L85E in with 3.73s and had it rolling on 30.5" tall 20s it got the best mileage it ever got. 2,500 rpm at 70 was a sweet spot between available engine power, torque multiplication from the gearing and drag. I would run down the road in lean cruise at 17:1 afr misfire free with 52° of timing advance with the CNP 24x setup.
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