Big Block

"HammerheadFistpunch" (hammerheadfistpunch) 08/25/2016 at 13:12 • Filed to: None

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8.1 liters, 496 Cubic Inches, iron block pushrod Big Block. Basically a stroked 454 big block. 340hp and 455 lbs-ft doesn’t really sound all that impressive today, but the torque curve is flat as a salt pan and it doesn’t rev out enough to make big peak numbers.

Here is also a comparison between the 4L60 and the 4l80 trans. You can see why the 80 is so much more durable than the trouble-prone 60.

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bhtooefr > HammerheadFistpunch 08/25/2016 at 13:24

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And then there’s the PSI 8.8:

537 CID big-block, inspired by the Vortec 8100 (but as I understand it’s actually a redesign), meant to go wherever a 454 or a Vortec 8100 goes, competes against the Ford 6.8 V10 for heavy duty gasoline/propane/natural gas applications (both offering more power in a high-speed tune, and more torque in a low-speed tune).

Apparently, for RV applications, the choices are 500 HP @ 4750/585 lb-ft @ 4000, or 265 HP @ 2800/524 lb-ft @ 2400: http://investors.psiengines.com/releasedetail.…

A bit bigger bore than the 8100, but much longer stroke.

I wonder how efficient it actually is...

I Will Always Be The Honey Badger > HammerheadFistpunch 08/25/2016 at 13:25

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Too bad you can’t fit standard BBC heads/intake on it, though.

JGrabowMSt > HammerheadFistpunch 08/25/2016 at 13:26

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Ain’t nothing a Thumpr Cam can’t help with.

HammerheadFistpunch > bhtooefr 08/25/2016 at 13:26

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Efficient? HA! none, none efficient. They stopped making the Big block in 2009, but its still in use in marine applications I think. Its a great motor in the traditional sense, but its not really made for the modern world.

HammerheadFistpunch > I Will Always Be The Honey Badger 08/25/2016 at 13:27

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yeah...but it takes to supercharging quite well.

Smallbear wants a modern Syclone, local Maple Leafs spammer > HammerheadFistpunch 08/25/2016 at 13:28

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8.1 was a BBC? I always thought it was LS-based.

TIL etc

HammerheadFistpunch > JGrabowMSt 08/25/2016 at 13:29

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Well...I mean you can spike the curve up a little in the middle with a new cam, but you aren’t going to get much more peak power out of it without raising the redline. We had a Vortec 7400 with a protec supercharger on it pushing 6-7 PSI and it MOVED in the midrange but it still redlines well below 5000.

HammerheadFistpunch > Smallbear wants a modern Syclone, local Maple Leafs spammer 08/25/2016 at 13:32

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Yup, just a BB 454 with a longer stroke.

JGrabowMSt > HammerheadFistpunch 08/25/2016 at 13:32

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Oh, I’m okay with the flat torque curve, but a Thumpr cam will make it sound a thousand times meaner while doing it.

bhtooefr > HammerheadFistpunch 08/25/2016 at 13:33

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The trick is that PSI still sees applications for the 8.8 in the modern world, which makes me wonder if they figured out something that GM didn’t regarding efficiency. And, there are plenty of techniques for getting a big gas engine to be more efficient - VVT strategies, friction reduction, combustion chamber design...

HammerheadFistpunch > JGrabowMSt 08/25/2016 at 13:33

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Truth, though a free flowing exhaust wakes it up quite a bit. We had tubular headers and twin 2.5 inch on ours and it sounded pretty great.

jimz > HammerheadFistpunch 08/25/2016 at 13:35

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Mercury Marine uses them, but I don’t know if GM still builds the engines, or if they sold the tooling to MM.

I Will Always Be The Honey Badger > HammerheadFistpunch 08/25/2016 at 13:35

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I’ve seen a number of the Mercury Marine 8.1's with the Whipple 2.8 or 2.9 supercharger on it, but not as much in vehicles.

HammerheadFistpunch > bhtooefr 08/25/2016 at 13:35

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The compelling reason for the 8.8 is simple - it’s WAY cheaper to buy than a diesel.

HammerheadFistpunch > jimz 08/25/2016 at 13:36

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I was trying to find that out but couldn’t locate any reliable info.

HammerheadFistpunch > I Will Always Be The Honey Badger 08/25/2016 at 13:37

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ours wasn’t the 8.1, we had the 7.4 with a protech in a Suburban, they can take 6-7 lbs no troubles in stock internals.

Haase > HammerheadFistpunch 08/25/2016 at 14:02

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Not 100% true. It also has Vortec heads. The older BBC intakes will not bolt up properly.

HammerheadFistpunch > Haase 08/25/2016 at 14:05

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I honestly couldn’t dispute your claim because I don’t know. I know the heads are (at least for the early versions) just basically vortec 7400 heads so it would stand to reason that anything that fits the 7400 would fit the 8100

swaptastic > HammerheadFistpunch 08/25/2016 at 14:08

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Some aftermarket heads and two turbos.... ohhhh my!

Die-Trying > HammerheadFistpunch 08/25/2016 at 15:06

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8.1 intake runner pattern

vs the classic bbc intake runner placement........

the top one comes in around $575, and is about the only variant for the 8.1.......... there are about a million variants of old bbc intakes, and cost is ballpark in the $280 range...........

ITA97, now with more Jag @ opposite-lock.com > HammerheadFistpunch 08/25/2016 at 17:24

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For awhile I owned a 2001 GMC 3500 (Crew cab, dually, 4x4) with the 8.l. It was a beast of engine, but it also got between 6 and 10mpg. 6 mph in town, 6mpg towing (up to about 10k, beyond 10K it fell to 4mpg) and 10mph when not towing on the highway. One of the nifty things about that truck is that it was exempt from most (gasoline) federal emissions laws of the time by virtue of its GVWR, so it was a 2001 truck that came from the factory without a catalytic converters.

HammerheadFistpunch > ITA97, now with more Jag @ opposite-lock.com 08/25/2016 at 17:27

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wow, that’s shockingly bad mileage. We had a supercharged 7.4 k2500 GMT400 that got 16 highway, and 12 towing, but it did have the 3.83 rear end so that probably made a difference.

I remember someone who drove an 8.1L truck pulling a large fifth wheel and he said the power was great “I could pass anything except a gas station.”

ITA97, now with more Jag @ opposite-lock.com > HammerheadFistpunch 08/25/2016 at 17:43

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Indeed. Mine had 4.10's in it.

SWITAWI > HammerheadFistpunch 08/25/2016 at 18:21

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Wow. Makes me think of the ‘98 GMC 3500 7.4L (Extended Cab, Dually, 5-Speed Manual) that my Dad is still kicking around in. It might have 120k miles on it by now.

We once got almost 14mpg on the way back to South Texas from Colorado because we spent the whole day driving downhill, lol.

But really the truck feels like it just doesn’t care. 12-13mpg when unloaded, 11-12mpg with a trailer and four horses.

It’s like an 80-Series with a truck bed and smaller cab.

HammerheadFistpunch > SWITAWI 08/25/2016 at 18:23

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yeah, we had a 97 k2500 burb with that engine, and a supercharger. Aint care, though it actually did BETTER for highway mileage with the supercharger for some reason.

SWITAWI > HammerheadFistpunch 08/25/2016 at 18:46

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Probably the same reason an otherwise-stock FJC or Tundra will get better mileage with the TRD Supercharger, the nice bump in T orque.

Makes setting off from a standstill more effortless and once it’s on the go the extra grunt helps the transmission stay in the highest gear on any grades.