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8.1 Vortec Engine Swap Questions

Sounds like it's not an issue now but last year Hot Rod magazine did a series of builds on a 6.0L. They got some good improvements in power without going crazy on the engine. Even when they did open it up the cost wasn't prohibitive.

Only thing I have to add is to me the LS series of engines are rather rpm friendly. You have to put your foot into it to get them to go.
 
I'm Scotts buddy who swapped in an 8.1 into his 75 blazer. I have some experience in this swap and alot have a few things for you consider. First is the new 8.1 is a huge and heavy pig. The first trip out with my new motor I found that my 52's were so sagged so much from the weight that I had almost no up travel. Second is that the standard 6.0 cross member doesn't work for the 8.1 its total different. You will need one built specifically for the 8.1. Now you also mentioned that you might want to swap in a manual tranny, which is what I have used in my blazer. The flywheel will need to be special ordered for this motor since its internally balanced and the old 454/7.4 fly won't work. Mine cost about 250 bucks. I would either go with the nv 4500 or the allison you will save yourself alot of troubles in the long run. The guys at pacific fabrication would be my first choice to do the motor swap they have do several 8.1 swaps and only use new stand alone harnesses. You will also need a much larger radiator as the 8.1 produces alot more heat than the 6.0, the 8.1 also has an external oil cooler which I mounted a fan too. The 8.1 take about 8 gallons of radiator fluid and 6 gallons of oil. You won't find anything with the low end torque but the weight and the rarity of the motor makes it difficult. The first winching with this motor my front springs twisted, which I think was due in large part to the extra weight of the motor.

Now for a touchy subject. I bought a 00 chevy 3500 which John deetz did the smog legal swap on. Now in fairness I don't have the whole history behind the swap but there were a ton of corners cut and in my opinion I would seriously take the time to drive down to see the quality of work Pac Fab is producing. John left installed a newly re-built 4L60 behind the 7.4 and within 2 weeks of non towing and one trip to LA the tranny was toast. Hope this helps....
 
After looking at all the things I would have to do with the 8.1, if I eventually do the swap, I am probably looking at the 6.0 instead. I have pretty soft TC EZ-ride springs up front with Ford shock towers and Bilstein 5150's. I don't want to be so front end heavy especially since I am already heavier than usual with all the mods I've done. Actually, I didn't want to go manual so my only option would be a 4l80E or an Allison. The 6.0 doesn't really need an Allison so the 4L80E would probably be the ticket. Again though, new crossmember, mods to the TC, new radiator and fans, and other gizmos that all add up. At this point, I am going to just do the gears and then see how that effects the hill climbing. I may also revisit just going with a 383 stroker too. I wouldn't get the power that I would with an LS, but the simplicity of the swap makes it attractive. I could move everything off of my 350 block right on to the 383 block, keep my current tranny and TC, and it would probably be fine.
 
I checked and an 8.1 weighs in at 761 lbs. dry weight.

You should drive my rig and see what you think. I just weighed it 3 weeks ago and it hit the scales right at 6,020 lbs with about 25 gallons of fuel and my 1 tons with custom front/rear bumpers. I built my engine 2 years ago and it is just a 355 but it pulls HARD. Of course the engine isn't stock either but people commonly think i have a BBC in it.

If you go with 5.13's i would love to drive your rig and see how those gears feel. I would like to do a gear swap to 5.13's but would really like to drive a like built rig with 5.13's first. I just can't justify the cost to gain to go from 4.56 to 4.88's.
 
what about performance parts from Raylar for the 8.1? the 8.1 has dual motor mounts cast into the block. you can bolt up SCB/BBC mounts directly too it. or LS style mounts. I'm not seeing how it would be more difficult to swap an 8.1 than a LS? it looks like it doesn't weight that much more than a standard bigblock.
 
The 4L80E weighs 40 lbs. more than my 700R4 at 174 lbs vs. 134 lbs. It looks like an LQ4 (Vortec 6000) complete engine weighs in around 530 lbs. Scott is right as another site listed the shipping weight of an L18, or Vortec 8100 as 734 lbs. So between the 8.1 and the 4L80E I would be adding about 250 lbs. give or take to my front end. And, this isn't distributed weight like a more gear spread around the back, or a passenger in the passenger seat, it is directly over the front axle and just behind it. By contrast, the HT383 weighs in about the same as the Vortec 6000 when fully dressed so if I just swap blocks, my weight stays the same is it is right now.
 
I might be the special one but my 8.1 didn't have dual mounting points for the crossmember:doah: I'm not saying that they don't exsist but there not on my 03
 
I had a 350/350 combo. The engine had a holley dual plane manifold, holley 700 double pumper, headers and a 228 @0.50 duration 0.480" lift cam. The trans had a 2500 stall converter. This was in a '71 Jimmy. I have changed it over to a stock 6.0 with a 700R4 from Bowtie ovedrive, level 3. The computer was reprogramed and the torque management removed. The 350 was tuned and ran very well. I have never been able to get the bugs worked out of the 6.0. With that being said the poorly running 6.0 runs just as hard as the good 350 did.
The bowtie TV cable works great.
 
If I could keep my 700R4, which I had built to Bowtie Overdrive Level 3 K-case specs, I might be more tempted. Since lovely Ca. smog laws are going to make me swap to a 4L80E, it adds more money and more complications. I plan on retiring out of state and if I was closer to that point, I would just wait until my smog was done, then do the swap and move before I had to smog it again. It is funny how my plans just kept tipping over the next domino.

First I was just going to swap the engine. Then it turns out I have to do the tranny, then the transfer cases have to be moved, or an Atlas installed. This then effects where the crossmember goes and changes where my TC levers come through the floor, which I had customized to accept the width of my 700R4 and my triple sticked doubler. Then my driveshafts might need changing again, and this effects my pinion angle so I have to make those changes. Then I would probably need to swap the radiator and go with electric fans. Then I have to do the drive by wire gas pedal. Then there is the interface with the old dash. After a while my head was spinning with all the things I was going to have to deal with.
 
Apparently if the engine was supposed to mate with an electronically controlled tranny, then you have to keep the combo. I find it strange since there are Ford F350's that up until 96 have PCM controlled MAF engines that mate to a C6, which is non-computerized. CORRECTION: The C6 looks like it disappeared in 96 with the advent of the OBD2 engines. I am guessing that DMV relies on the manufacturer specs. In other words, you have to stay with a combo that the manufacturer offered and you can't mix and match unless both on non-computerized. Here is what CARB says (http://www.arb.ca.gov/msprog/aftermkt/replace.htm):

[FONT=Arial, Helvetica]Engine Changes[/FONT]

[FONT=Arial, Helvetica]Engine changes are legal as long as the following requirements are met to ensure that the change does not increase pollution from the vehicle:[/FONT]
  • [FONT=Arial, Helvetica]The engine must be the same year or newer than the vehicle.[/FONT]
  • [FONT=Arial, Helvetica]The engine must be from the same type of vehicle (passenger car, light-duty truck, heavy-duty truck, etc.) based on gross vehicle weight.[/FONT]
  • [FONT=Arial, Helvetica]If the vehicle is a California certified vehicle then the engine must also be a California certified engine.[/FONT]
  • [FONT=Arial, Helvetica]All emissions control equipment must remain on the installed engine. [/FONT]
[FONT=Arial, Helvetica]Transmission or Transaxle[/FONT][FONT=Arial, Helvetica]Transmissions and transaxles changes alone are not legal. Transmissions and transaxles can only be changed along with their matching engine. The total engine transmission package must conform to the engine change requirements above.[/FONT]
 
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If i were you i would make a call to your local referee and ask him if you need to change the transmission as well. Might even be better to tell them you have a 1976 blazer and want to install a 6.0 engine and ask them what things you WILL NEED. Based on what they say then you could bring up the fact that you already have installed a 700R4 transmission years ago and ask if you must also change the trans (again).
 
Apparently the local referee seems to be at the local college and I am assuming it is the auto shop teacher. I may have to pay the referee a visit first. Although, the PITA is that they won't tell you who the referee is until you make an appointment. I might have to do just that and see what they say. I am inclined to think that you can't swap a transmission into a rig unless the vehicle had it as an option. For example, the Blazer eventually went to the 700R4 after the TH350 and TH450 series in conjunction with carbed non-computerized engines. I also agree that the referees are probably good with putting new engines and transmissions in older rigs since it is essentially making an older truck new in some respects. Where they get their undies in a wad are folks who try and retrograde by putting old engines and transmissions in newer trucks.
 
Desert Rat said:
No replies from somebody who has actually done the swap with an LS 6.0 or 8.1 yet. Somebody must've done the swap and are driving a Blazer with either engine and the new tranny.
Click to expand...

For what it's worth, I am getting ready to test fit a 8.1/allison combo into my 75 Blazer this weekend. I got the combo out of a wrecked 2003 GMC 2500HD.
I got all of the wiring and I will be retrofitting the steering column and the pedal assemblies into the Blazer.
I was torn between building a 383 and a 454. Long story short, I found a deal on craigslist I couldn't pass up. $2400 for the whole thing including the brake setup and a 14bolt with disc brakes.
I will be taking pictures and will post as this task progresses.
 
Fantastic, I recommend a build thread for it as many will be interested. Pics are always nice of course....
 
8.1 vortec engine
81002.jpg


dual mount pattern
81001.jpg


stout bottom end - internally balanced.
81003.jpg


goes pretty good in a '69 vette with a richmond 6 spd. and It'll go pretty good in my '73 Z-28 with Tremec T-56.
81004.jpg
 
Here is a link to a "budget" LQ9 408 stroker build. Long story short, 550hp and 500ftlbs.

Could you use a 4L60E instead of a 4L80E to meet the smog requirements without using the longer trans?
 
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