8.1 Liter into an '86 Crew Cab

[Blake_H]

Hello,

I am new to this forum, but I joined so I could find some answers.  I have a 1986 Chevy crew cab with a tired 454 in it.  I want to, or am curious if, anyone has swapped out the 454 for the 8.1 and kept the wiring and ecm, and what kind of issues did they run into.

I would like to upgrade the transmission with this swap.  The setup I am looking at is an 8.1 with all the wiring, accessories and ecm.  It also has a 4l80e with it.

Any advice, knowledge on this would be greatly appreciated.

Thanks.
Blake

[team39763]

Are you talking about those newer 8.1's?  I thought I read somewhere that they were similar to the older BBC's but also very different.  If you're talking about doing a complete transplant with everything from the 8.1 donor vehicle, I heard that it has been done.  I've also read that there isn't much reasonably priced aftermarket parts for the 8.1L.  I remember seeing a [2001?] 1/2ton with a 8.1 swap and I believe they said they spent over $20K on the truck.  Yours may not be that bad since you already have a BB and you won't need to re-do the frame or firewall or anything like that.  Anyway, good luck with it.  I'm sure somebody will jump in and give you some better advice.

[SUX2BU99]

You don't hear too much about those 8.1s. Maybe they tanked because you get get the same or better HP from the 6.0 and a whole lot better aftermarket support without the bad mileage and expensive parts of an 8.1? Like Team said, there are some basic similarities I recall of the 8.1 to the MKIV BBC but overall there's lots of differences. I wouldn't expect to be able to use any older BBC parts on the 8.1. But hey, if you can get the motor and trans for cheap, then go for it!

[VileZambonie]

You may have clearance issues with the oil pan but I believe there is an aftermarket pan available. Would be a nice retrofit!

[Captkaos]

realsquash on here has done it on his truck...

[Blake_H]

Thanks for the input on this and the photos.  At least I now know someone has done it.  I am talking with a guy that has the complete motor & trans. Plus he has the harness and ecm.  The engine was rebuilt, as he was going to use it in a '61 Buick, but changed his mind.  He put new rings and cleaned up the clearance to avoid the piston slap.  He also cleaned up the heads and intake.  I will have to clean up and make the transmission stronger to handle the load of the trailer, but that doesn't bother me to much.  So, I'm not to worried about the engine & transmission, just the conversion.  It's doing this, and making the gauges, cruise control, fuel pump & new tanks, etc. work properly.  I've even seen the recall info, and plan to replace the cam & crankshaft sensor before it goes in.  I have a great parts guy at the local ACDelco parts store. 

My thinking is that if I have to pull the old BB because it is tired, then why not replace it with more torque and horsepower, that allegedly will get "better" mileage while I'm driving it to Home Depot and back.  The truck will primarily be pulling a 42' trailer over Donner Pass into California 5 to 6 times a year to go to the races.  The rest of time, the truck sits in the garage, unless I need to get something big for the honey-do list.

I built a 63 Buick Special Convertible and installed a 327 with a carb and a 700-R4.  That was easy compared to this.

Thanks for the help, and I'm glad I found this place! 

[team39763]

Well if all you're worried about is gauges,fuel system, and cruise....you don't have much to worry about bro.  You might aswell do the swap.  I've read that they get better mileage than the Vortec 454.  And with a few bolt-ons(like in those pics above), I'm sure it would make some good power too.

[Captkaos]

If the engine comes with a trans, get it, it will handle pretty much anything stock as it would be the 4L80E.  You need the ECM and harness, integrating the gauges will be comparably simple.

[choptop]

May wanna double check the tranny. Every 8.1 I have had and seen had the Allsion tranny. I havent seen one with the 4L80e. Regaurdless, either tranny is more than adequate for a mild built engine, and the 4L80E will handle more than the Allison. I have yet to hook up to anything I couldn't pull with ease in stock form.

[Captkaos]

Thanks for pointing that out.  Your right, it should be an Allison..

[realsquash]

That 76 GMC is mine, but it's a Vortec 454, 2000 model year.  The 8.1 is not 100% the same, but the engine swap itself is nearly the same.  You will need the ECM reprogrammed to remove some things for emissions and whatnot.  At that point you can have torque management removed as well, you'll get some more power out of it that way on the low end (like you needed it).  I'm running 2 O2's instead of 4, no cat, no EGR, no AIR, no evap, nothing.  No codes due to the reprogramming.

I am running an old-school TH350 that I rebuilt, so no electronics at all.  The PCM is set up for a manual transmission and a few things are disabled so it doesn't set codes.  The 8.1L could be had with a 4L80E in some other applications but I've only seen them with the Allison or 6-speed manual in the pickemups.  Running the transmission shouldn't be a problem.

There are a few guys who do mail-order reprogramming.  You UPS your PCM to them with $100 or so and they do what you need.  My experience has been good with that.

The only gauge you need worry about is the speedo.  You might have to buy something fancy to do that if you have a cable speedo (I'm guessing you do).

Andy

[bigkountry]

http://www.gowheatley.com/index.html

Charlie did the tune in my 01 Silverado, great guy and knows his stuff!

There are others Nelson, Wait4me, Westers and independants with the right software, but Charlie is a down to earth kinda guy. Customer service is top priority when I choose a supplier or service.

[Blake_H]

Thank you guys very much for all help.  The motor will be here in 10 days.  Trans arrived today.  Will post as the project gets going.  We won't start anything until the honey do list is complete or the snow flies, whichever comes first.

As things come up, I'll be sure ask here.  Thanks again!

[jw454]

Just to take all the "mystery" out of the 8.1 litre, it is a 454 with a 1/4 stroker crank, that equals 496 cubic inches. It is most likely a gen. 6 block and parts are indeed readily available, as many of the mark iv parts are compatible with a gen. 6. It is widely used in the marine industry and has been a great success as has been the 454.

[farmallgray]

That 76 GMC is mine, but it's a Vortec 454, 2000 model year.  The 8.1 is not 100% the same, but the engine swap itself is nearly the same.  You will need the ECM reprogrammed to remove some things for emissions and whatnot.  At that point you can have torque management removed as well, you'll get some more power out of it that way on the low end (like you needed it).  I'm running 2 O2's instead of 4, no cat, no EGR, no AIR, no evap, nothing.  No codes due to the reprogramming.

I am running an old-school TH350 that I rebuilt, so no electronics at all.  The PCM is set up for a manual transmission and a few things are disabled so it doesn't set codes.  The 8.1L could be had with a 4L80E in some other applications but I've only seen them with the Allison or 6-speed manual in the pickemups.  Running the transmission shouldn't be a problem.

There are a few guys who do mail-order reprogramming.  You UPS your PCM to them with $100 or so and they do what you need.  My experience has been good with that.

The only gauge you need worry about is the speedo.  You might have to buy something fancy to do that if you have a cable speedo (I'm guessing you do).

Andy

Could probably use a speedo out of a 91 blazer or Burb.