Vortex to mechanical 6.2 conversion

[Linhster]

Got a 99 Tahoe that I will be doing a conversion to diesel. Would love some insight to any obscure details that I might have missed in doing research for this project.

Original: 5.7 vortex injected 2 door Tahoe with 4l60e.

Conversion: 6.2 TD studded heads with mechanical IP. ESS will be from 6.5 front mounted sensor. TPS is from humvee style TPS with a 5v reference. Hydromatic Power brake and steering. Low stall TC for 4L60e.

Concerns.
- OEM computer to control the 4L60e with lower stall converter.
- O2 sensors (check engine light)
- 4L60E ability to handle the torques without towing
- ABS issues
- speedo
- existing fuel pump over pressuring the IP.

Thanks in advance for any insights .

[DieselDavy]

There are a few 2 dr Tahoes out there that are already diesel with all of the 'diesel' stuff already there. You might want to start with one of those. Just a thought.

[trbankii]

Typically, swaps need to be to a same year or newer engine - so a 6.2 into a '99 isn't going to fly.

As Davy says, the 2-door 6.5TD Tahoe/Yukon was available - like my '94. It would be a lot easier to find one of those than go through the conversion. Even if you have custom work done to yours, it is likely easier to swap those items over to a 6.5TD model.

Other than that, they put the 4L80E behind the 6.5TD. A 4L60E could probably live behind a 6.2 (if that happens to be legal in your area), but then you're also talking less power without the turbo. You'll likely notice a drop from the performance of the 5.7 Vortec.

Separate computers are available for standalone 4Lx0E swaps, but cost you money. Without the computer for the mechanical 6.2 there won't be a check engine light. So no O2 and the ABS and speedo will have to be dealt with accordingly - you're not going to have the gasser computer still in the equation. You'll want the diesel lift pump, not the gasser setup.

[DmaxMaverick]

The N/A 6.5L was available with the 4L60E tranny, but I don't believe the Tahoe was a candidate. The 4L60E is essentially the electronic upgrade to the TH700R4. The correct OEM torque converter is available, but custom is better (and more $$). You could do this with a 6.2L, but a N/A 6.5L would be a much better build.

As you suspect, the electronics will be the bugger. I suggest sourcing a similar year PCM (OBD standard for that model year) and powertrain harness, and have a custom PCM program done to accommodate the features of the Tahoe that aren't optioned in the N/A 6.5L pickup/chassis. The year models need to be similar to accommodate the tranny electronics. Yours is a 99, so earlier models won't work with a later tranny. Research the 4L60E evolution to determine which years can be used. This is critical, as the late model trannies don't live long without effective torque converter lockup control. Simplify the job by sourcing a correct year model Diesel Tahoe that's used up or wrecked. As long as you have all the sensors in place, and the powertrain harness is correct, it shouldn't be that big of a deal. It will also have the accessory drive components that you'll need.

You will want to replace the gasser fuel tank sender/pickup with the correct Diesel unit, and install the Diesel fuel lift pump system. Lift pump controllers aren't cheap, but much advised to simplify the process, and start with a durable system that won't plague you later (because it WILL if you don't).

Go to www.kennedydiesel.com for the lift pump controller and custom PCM calibration, and probably a long list of other things you aren't likely to find easily elsewhere.

[DieselDavy]

You might want to contact me. I am thinking about selling my 97 2 door Tahoe.
d

[sctrailrider]

You might want to contact me. I am thinking about selling my 97 2 door Tahoe.
d

I might be interested....

[More Power]

You might want to contact me. I am thinking about selling my 97 2 door Tahoe.
d

Say it ain't so!

Back to the topic... The TCM computer used behind a gas engine won't work with a diesel... The shift points will be all wrong because of how different the RPM ranges are for the two engines. Jim