just to make clarification - the article that is in question, that motor is being put into a 73-87 frame - not the 88-98.

Right u are sir, I saw 88 and assumed it was my body style, apparently 88 year models were like 99 year models, they produced both. Looking under the hood and seeing the fan box is a dead give away that it is the 73-87 frame.

Nytmarek5 wrote:

Is that from the Offroad unlimited baja suburban build? The info looks very familiar that's why I ask. As far as I've seen Raylar? I have heard is the only one to do anything for aftermaret heads. My main point with the "cam and tune" is all the 6.0 guys claim better fuel efficiency factory mpg goes out the window when you start changing fuel mapping and cam and ignition timing... And it's very dependent on driving style. Although I will throw it out there that with a tune you can make an engine more efficient but generally not if you are shooting towards peak performance... The whole reason performance lacks from the factory is because they are shooting for the best balance between power, efficiency and reliability (in theory).

The one thing that does suck about finding them with a complete harness and ECM is that generally you have to send the ECM put to get flashed anyway to get rid of the VATS system and the torque management thats programmed in them.

Some of the 8.1 info I listed was from the 2002 GM Performance Parts catalogue which lists the HP3 Vortec 8100 as a crate engine which was to be released in 2003. It was rated at 525+hp@5400rpm and 560 lb/ft torque@4000rpm.
The company I was talking about is NOT Raylar, Raylar makes aftermarket heads. The HP3 Vortec 8100 used stock iron heads that were ported by the U.S. company. This company CNC ported about 60 sets for GM Performance PArts so that GMPP could do in house testing as well as supply a 9 American Power Boat Association (APBA) race teams with 8.1 engine parts. Race teams which use dteh HP3 8100 were members of "Team Vortec". These race teams competed in 2002 and the HP3 Vortec engines broke 2 world records The UTZ Quality Foods/Castaway powerboat in the Super Vee Light Twin class posted a speed of 106.167mph and the Vortec Team Extreme (Kava Kava/Air Jamaica) powerboat in the Super Vee Light Single class reached a speed of 89.672 mph.

GMPP 8100 Marine Crate Engines come from GM in these flavours:
HP1 390hp
HP2 420hp
HP3 525hp-stillborn
Unfortunatley the HP3 was never released to the public through the GM dealership/GMPP parts counters.

Here is a copy of the GMPP specs on the HP3 crate engine
-------------------------------------------------------------------------------------------------------------------------------------------
2003 Vortec HP3 8100 High Performance Crate Engine
Specifications

Type: 8.1L V8
Displacement: 8127 cc (496 cu.in.)
Compression ratio: 9.1:1
Valve Config.: Pushrod actuated overhead canted valves ( 2 valves per cylinder )
Valve Lifters: Hydraulic roller
Firing Order: 1-8-7-2-6-5-4-3
Bore & Stroke: 107.95 x 111.00mm (4.25 x 4.37 in.)
Main Bearing Caps: 4-bolt cast iron
Balance Method: Internal engine balance
Intake Manifold: Factory-installed PFI (equal length runner) manifold
Oil Pan Capacity: 8 qt . (7 quart fill level after system charge)
Fuel Type: Gasoline (unleaded)(87 octane)
Fuel System: Port fuel injection
Horsepower: 525HP @ 5400 RPM
Torque: ( lb-ft ) : 560 lb-ft @ 4000 RPM
Engine Rotation: Clockwise (facing front of engine)
Spark Plugs: Platinum (1.5-mm gap )
Emissions Controls: Internal PCV orifice system
Paint Protection: Component painted
Shipping Weight: 734.14 lb (333 kg)
Materials
Block: Cast iron
Cylinder Head: Cast iron
Intake Manifold: Coated cast aluminum
Main Bearing Caps: Cast nodular iron
Crankshaft: Cast nodular iron
Camshaft: Steel
Connecting Rods: Forged steel (1141SAE shot-peened and magnafluxed with 9mm diameter bolts)
Pistons: Hypereutectic coated cast aluminum
Manufacturing
Assembly Site: Tonawanda, New York
-------------------------------------------------------------------------------------------------------------------------------------------

PCM tuning is easily attained nowadays, many of us members of the PPE truck site family have the ability to do our own tuning. I use Tunercats 2 personally as do others here, but EFILive is more popular.
VATS disabling is a click of a mouse. Depending on which transmission was being used and in what application would dictate how much torque management (TM) I took away or added.
The 8.1 truck applications have very mild PCM tuning. There is lots of power left on the table. On some of the 4500+ trucks 60rwhp can be had. The gains in the 2500HD/3500 trucks are a bit lower, but 40rwhp gains are common from PCM tuning alone. So long as A/F ratios and ignition timing are not causing excessive combustion temps or detonation actual engine longevity wont be compromised. I cant say the same for anything behind the flexplate however lol.

I dont think that any 6.0 that has been cammed and modified to make substantial power gains would get better fuel economy than a stock setup. I would find claims like that highly suspect. I agree with you as well, fuel economy is directly related to driving style. IMO fuel economy really isnt a huge concern in performance builds, esp. when discussing 454/502's and 8.1's.

Its too bad the GM is no longer building the 8.1 after 2010 in any capacity. It appears that GM Marine is going with the blown 6.2l GEN 3 SBC as well as the good old 454/502.
Marine LSA 6.2l 530hp@5400rpm/545 lb/ft torque@4000rpm.
http://www.gm.com/experience/technology/gmpowertrain/engines/specialized/marine/2010_6200_LSA_Marine.pdf

peace
Hog

The frames on the older 73-86 Chevys are literally identical all the 2wd suspension is bolt on with about six or eight bolts. And the frames are even pressed with the bolt holes for all the 4x4 stuff the 1 ton frames are different underneath the bed I think the steel is taller like 2x5 maybe instead of 2x4 (those are made up number but just and example) and the frames are a few inches wider in the back to make the trucks more stable with less body roll <--- this would also hamper articulation cause the springs are mounted farther out on the axle, so if it's going to be used in the woods 1/2 or 3/4 ton would be the way to got for that year frame.

The 87+ 2wd is a totally different frame for the 2wds but as far as strength goes there should be no difference. You also have to think they do make 2wd 3/4 ton and one ton trucks I believe the one ton truck usually have beefier frames in the back underneath the bed but usually the 1/2 and 3/4 tons share all the same components they just change spring rate, hub size over to 8 lug and gear ratios in the axle.... If you want to be super crafty look for a 2wd 3/4 or 1 ton and then you get a 14 bolt FF to start with also now that the economy has tanked all these trucks and thier parts axles/t cases/ engines are all dirt cheap cause you have alot of unemployed people out there selling the stuff they can't afford so there are some amaIng deals out there if you do some looking.

Interesting info hog, I had never come across that. You said they never produced the three different stage heads though right? Or rather didn't release them to the public? I guess that why everyone told me Raylar was the only manufacturer but porting stock heads is one option I didn't really consider so that opens up some options. I am mainly going for a stock build with a custom tune and 80mm TB and headers very mild, very reliable, and the non-smog engines I have heard should be pushing around 505 hp. I won't be racing the truck and generally on the trail the more nuts you go powerwise the farther home you have to walk lol. Basically my truck is a K series blazer with a 2002 2500 Avalanche drive train and a doubler slapped on the end. I'm generally going for the strongest truck I can build. That's my motivation. Now I know my truck is the older body style but I'll be looking into the options for the 88+ trucks while I'm diggin around (just cause I like you guys) and I want the most info on 8.1 swaps I can get.

On the 73-87 frames, you do need to inspect the steering box mount area on the 4WD trucks as the frame is prone to cracking at this point. This is one of the very few flaws on the best trucks ever built.

Nytmarek5 wrote:

Interesting info hog, I had never come across that. You said they never produced the three different stage heads though right? Or rather didn't release them to the public? I guess that why everyone told me Raylar was the only manufacturer but porting stock heads is one option I didn't really consider so that opens up some options. I am mainly going for a stock build with a custom tune and 80mm TB and headers very mild, very reliable, and the non-smog engines I have heard should be pushing around 505 hp. I won't be racing the truck and generally on the trail the more nuts you go powerwise the farther home you have to walk lol. Basically my truck is a K series blazer with a 2002 2500 Avalanche drive train and a doubler slapped on the end. I'm generally going for the strongest truck I can build. That's my motivation. Now I know my truck is the older body style but I'll be looking into the options for the 88+ trucks while I'm diggin around (just cause I like you guys) and I want the most info on 8.1 swaps I can get.

GM produced the HP1 (390hp) and the HP2(420hp) units, but the HP3(525+hp/560 lb/ft torque) wasn't released to the public. Maybe GM didn't want direct competition for the Ramjet 502? Who knows.
Mercury/Mercruiser sells the HP1 as the Horizon 8.1 370hp and the HP2 as the 8.1HO 420hp as an inboard engine. And 496 MAG 375hp and 496 MAG HO 425hp for sterndrive applications.

Raylar is the only company that I know of that makes aftermarket heads for the 8.1 Vortec.

An 8.1 should work well in your truck.

peace
Hog

Hog you seem to know a good deal on the specs....I had heard a rumor that the 8.1L's were sold under one casting number as a 496 and a different casting number as a 502 suposedly from the factory? I never saw anything concrete on this but a "local" at a parts store claimed this was true....Although I had presumed if this was the case it would have been in a 4x4 mag or some chevy performance mag as "look for this casting number (its a secret)" like they ususally have once a year or so. But then again everyone seems terrified to use this motor.

Hey guys just checking in but I recently aquired a 454 so if anyone is curious of direct measurements between the two I now have a growing collection of big blocks.

some side by side pics would be cool

I didnt think the 8.1L came in the GMT400(GMT400 style) heavy duty's. I wonder how different the front end of the frames are between this 3500 and a 1500. In any case for those of you doing the swap it may be something to investigate parts wise. Maybe y'all already knew about this application...
http://www.purplewave.com/cgi-bin/mnlist.cgi?100330A/3260

TJ

98Blackss wrote:

I didnt think the 8.1L came in the GMT400(GMT400 style) heavy duty's. I wonder how different the front end of the frames are between this 3500 and a 1500. In any case for those of you doing the swap it may be something to investigate parts wise. Maybe y'all already knew about this application...
http://www.purplewave.com/cgi-bin/mnlist.cgi?100330A/3260

TJ

thats pretty much a kodiak under there with a body thrown on top. notice the leafs in the front?

its different the the regular 1500-3500 frames. can turn on a dime too. lol

would like to get that thing though.....look at all them parts........

There are some rare and cool GMT400-specific parts on that!
- PCM bracket
- Electronic accelerator pedal
- Air filter box and inlet tube
- A/C lines
- Fuel lines
- WIRING HARNESS!

I wonder if it's got a 4L80-E or a 5-Speed Allison 1000

James B. wrote:

There are some rare and cool GMT400-specific parts on that!
- PCM bracket
- Electronic accelerator pedal
- Air filter box and inlet tube
- A/C lines
- Fuel lines
- WIRING HARNESS!

I wonder if it's got a 4L80-E or a 5-Speed Allison 1000

im thinking its the same as the rollbacks/tow trucks/and other heavy use vehicles, so i put money on the Allison.......

somebody really should grab that, i would if i had the time to sit and watch it so i dont get outbid - but i dont

I'll post pics of the 454 and 8.1ls when I get home the 14th or so. It's out of a boat so the oil pan I'm sure would be different but I'm getting close to the actual swap so I'll post pics of it landing into the cradle soon hopefully. Just gotta get the doubler and torque converter.

nice thread

figured i should update this thread of mine...

I think I posted a couple pages ago that I sold the 97 this was going to go in, and picked up an 01...

Well I'm about to buy a 92 k2500 and this will be going in that truck. So the swap is still going to happen...Albeit a little differently than before. Not sure what I'll do about gauges yet..I am thinking of swapping the dash to a 95+ so I can use the 0411 PCM and have stock gauges...My other idea is to use a 57 chevy dash and fab it to fit to give it an old school feel.

Will keep you posted.

95 & 0411 sounds good...but the 57 dash sounds VERY cool.

Been a while since I updated this. I've been working ridiculous hours and haven't gotten a chance to touch my truck. Although the bright side is I've been buying a shit ton of parts with the extra cash... My DD ate itself so I bought a new truck also (when it rains, it pours right). But here's some new info.

Stock k-series 454 manifolds will work in place of the 8.1L manifolds. For the 73-87 trucks the ORD bigblock crossmember will work with a 3/16 plate under the engine mounts for a little added clearance.

Now biggest clearance issue for the GMT400 trucks and the 73-87 is the drivers side front corner of the oil on a 454 it has a rounded pan on the 8.1L it is a squared aluminum pan. So with the GMT400 trucks you will have to fab a new engine crossmember and or notch the factory one (I don't have one of these trucks to measure so can't tell you how much).

With that said if you are going to do an SAS then you can incorporate this
mod into your planning for removing the IFS crap and putting the new axle in.

I sold my 454 but before I did I measured it and it's really only 3" narrower then the 8.1L and the only size issue that poses is with the exhaust manifolds. Which has been previously mentioned and solved.

Now I need to give Dirty Larry credit for helping me out with several of these issues, he also addressed fueling issues and said he solved them with a fuel pump from an 87 corvette and new larger diameter high pressure fuel lines. Also when searching for an 8.1L complete look for 02 and older as their fuel rail has a return line you will need that new styles don't have. And also there are two different valve covers offered so make sure you get the right coils for your engine. (I lucked out on both of these issues and happened to have both cause I have two different engines)

Hope this sheds a little more light