Help with a 1st gen question

[EWalshak]

I need some info from a 1st gen person. I would like to know what kind of RPM you guys are doing on the highway with a 3. 55 geared truck. Im repowering a suburban which has 3. 73(will be relatively close to 3. 55s). I found a good donor vehicle for the engine and trans, but the trans does not have overdrive. The donor is an 89' D350. Also,are there any differences between the non-intercooled and the intercooled 1st gen, other than the addition of the intercooler. Thanks in advance for any info.

 

[Wiredawg]

I see right about 2,000 RPMs at 70 MPH. Interesting, whenI was stationed in Icelend in 1982, the Icelander wanted Suburbans to install Volvo diesels in. They were pretty cool the way they dressed them out.



Let us know the outcome of your project



Wiredawg

 

[EWalshak]

Thanks for the info Wiredog. Do you know if all the 1st gen transmissions had overdrive. Ive looked at a few trucks on ebay that claimed to have overdrive but the gear selector/indicator thing on the dash only had 1,2,3. Thanks

 

[Wiredawg]

I don't know a lot about the autos, but I do know a friend had a '90 auto and it did not. I imagine the transmission was geared higher though. You may want to search the 1st Gen website and/or wait for someone smarter than me :-laf to add to info your question.



I think it's a cool idea to put aa Cummins in a Suburban. Please keep us posted on your progress and be sure to post pics.



Take care, Wiredawg

 

[EWalshak]

Wiredog, Does your 93 have overdrive? Or is it 1,2,3?

 

[SRadke]

They started with od autos mid 91 I believe. They'll say 1,2,3 on the selector with an elec od button on the dash.

3. 55's and 31" tires in direct will put 2000 rpm very close to 50 mph.

-Scott

 

[Wiredawg]

EWalshak,



Mine is a 5-spd standard... 5th is overdrive.

 

[PToombs]

Pre 91. 5 had the 3 speed with 3. 07 gearing. Post 91. 5 had the OD trans with lower gearing, 3. 55's usually.

The IC trucks have smaller diameter injectors, the computer runs more things, and obviously, the IC.

 

[cerberusiam]

What transmission do you have in the 'burb?



The adapters are available for the GM units and with a custom TC the 4L80E is a good match for a 1st gen engine even with a few tweaks.

 

[EWalshak]

Thanks for the input cerberusium. My quest is making progress. I will be picking up the donor vehicle for the suburban project this Saturday. Its a 92 D350 Auto w/od. I am planning to use the trans that is in the dodge for the conversion.

 

[cerberusiam]

Thanks for the input cerberusium. My quest is making progress. I will be picking up the donor vehicle for the suburban project this Saturday. Its a 92 D350 Auto w/od. I am planning to use the trans that is in the dodge for the conversion.

The reason I ask is you will not have a lockup TC with the 92 trans unless you upgrade it. If you 'burb came with a diesel or big gas engine it would have a better transmission with fewer tweaks than the 46RH in the Dodge.



Just food for thought.

 

[EWalshak]

The reason I want to use the dodge trans is mainly for the fact that it will save me from having to buy the stand alone controller. I can always upgrade later. This ride will be used more for around town than anything else with only the occasional highway trip, which is where you would see the most benefit of the kock up converter,

 

[cerberusiam]

The reason I want to use the dodge trans is mainly for the fact that it will save me from having to buy the stand alone controller. I can always upgrade later. This ride will be used more for around town than anything else with only the occasional highway trip, which is where you would see the most benefit of the kock up converter,

Gotcha



I thought the trans controller was seperate on the GM's of that year. Is it integrated into the engine ECU or ??

 

[EWalshak]

Im not sure. Im guessing its integrated into the ECU or ECM? I ran the numbers both ways. Piece meal the project, salvage yard motor,A/C and alternator mounts,intercooler,(adapters w/flexplate and starter) stand alone controller for trans. Motor mounts. VS Donor vehicle w/ non electronic trans w/OD Motor mounts,A/C, alternator mounts. It would have cost more for the first scenario. With the second option I can sell off all the parts left over to try and recoup some of the $ that I have into the project.