if bigger is better, anyone stuffed an 8.1 in a halfton
Nov 30, 2004 | 04:36 PM
#61
On The Tree
Joined: Jan 2004
Posts: 133
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From: Omaha, NE
Originally Posted by smooth sierra
The 8.1 DOES NOT like boost. the marine industry has found this out several times. they are okay up to about 6 psi and then they start breaking pistons. the pin location in the piston is higher up resulting in the 'meat' between the top compression ring land and the top of the piston to be less. they consistantly break pistons when you put the squeeze on them.
the 8.1 is a stroked 454. it is my understanding you cannot stroke it any further without block modifications.
I doubt the CAST crank would hold up to 1500 hp and that is assuming you studded the bottom end to keep the caps from walking.
on a good note should someone decide to venture there with the 8.1 there are alot of 'goodies' available aftermarket in the marine industry for this engine. ie. aluminum heads, cams, ignition etc. the 8.1 is pretty popular with mercruiser and is actually pretty common in the hotboat world today.
Be fore warned they do not like boost though!!!
the 8.1 is a stroked 454. it is my understanding you cannot stroke it any further without block modifications.
I doubt the CAST crank would hold up to 1500 hp and that is assuming you studded the bottom end to keep the caps from walking.
on a good note should someone decide to venture there with the 8.1 there are alot of 'goodies' available aftermarket in the marine industry for this engine. ie. aluminum heads, cams, ignition etc. the 8.1 is pretty popular with mercruiser and is actually pretty common in the hotboat world today.
Be fore warned they do not like boost though!!!
Aha!!! AS I read through this post, you beat me to what I was just about to point out... the bottom ends on the 8.1s are WEAK. I know a guy here in town who makes a living salvaging them out of delivery trucks. He built one and told me that you need to spend a fortune in the bottom end to make it hold power. The 8.1s do NOT have the structural integrity the LS1 design does - hence it cannot take NEAR the power increase on stock internals. No way will it put 500 to the wheels without a complete and expensive redesign.
Boost is the way to go... you increase your effective displacement while boosting, then back to normal when not boosting. THose extra cubes only do you good at full power - at anything other than WOT, you're wasting energy and getting worse fuel economy...
As for truck pulling... errr, it's OK I guess. My daily driver has 260,000 miles on it and puts out 600 ft-lbs at the wheel, on the same Mustang dyno Parish is headed for this weekend. Duramaxes are OK (better than the 6.0PSD) but when they start catching the Cummins trucks at the truck pulls, then we'll call it the King... it should be noted that this year, the Duramaxes often ended up in the top three at the major midwest pulls, so I give it some credit. But it isn't the greatest thing in the world. That title is reserved for the Cummins!!!
Go ahead and build that 8.1, if it puts out more than 600 ft-lbs at the wheel, I'll tip my hat to you!
-scott
Nov 30, 2004 | 06:04 PM
#62
Originally Posted by dieselgeek
Aha!!! AS I read through this post, you beat me to what I was just about to point out... the bottom ends on the 8.1s are WEAK. I know a guy here in town who makes a living salvaging them out of delivery trucks. He built one and told me that you need to spend a fortune in the bottom end to make it hold power. The 8.1s do NOT have the structural integrity the LS1 design does - hence it cannot take NEAR the power increase on stock internals. No way will it put 500 to the wheels without a complete and expensive redesign.
Boost is the way to go... you increase your effective displacement while boosting, then back to normal when not boosting. THose extra cubes only do you good at full power - at anything other than WOT, you're wasting energy and getting worse fuel economy...
As for truck pulling... errr, it's OK I guess. My daily driver has 260,000 miles on it and puts out 600 ft-lbs at the wheel, on the same Mustang dyno Parish is headed for this weekend. Duramaxes are OK (better than the 6.0PSD) but when they start catching the Cummins trucks at the truck pulls, then we'll call it the King... it should be noted that this year, the Duramaxes often ended up in the top three at the major midwest pulls, so I give it some credit. But it isn't the greatest thing in the world. That title is reserved for the Cummins!!!
Go ahead and build that 8.1, if it puts out more than 600 ft-lbs at the wheel, I'll tip my hat to you!
-scott
Boost is the way to go... you increase your effective displacement while boosting, then back to normal when not boosting. THose extra cubes only do you good at full power - at anything other than WOT, you're wasting energy and getting worse fuel economy...
As for truck pulling... errr, it's OK I guess. My daily driver has 260,000 miles on it and puts out 600 ft-lbs at the wheel, on the same Mustang dyno Parish is headed for this weekend. Duramaxes are OK (better than the 6.0PSD) but when they start catching the Cummins trucks at the truck pulls, then we'll call it the King... it should be noted that this year, the Duramaxes often ended up in the top three at the major midwest pulls, so I give it some credit. But it isn't the greatest thing in the world. That title is reserved for the Cummins!!!
Go ahead and build that 8.1, if it puts out more than 600 ft-lbs at the wheel, I'll tip my hat to you!
-scott
Philip S.
Nov 30, 2004 | 06:51 PM
#65
Originally Posted by dieselgeek
Aha!!! AS I read through this post, you beat me to what I was just about to point out... the bottom ends on the 8.1s are WEAK. I know a guy here in town who makes a living salvaging them out of delivery trucks. He built one and told me that you need to spend a fortune in the bottom end to make it hold power. The 8.1s do NOT have the structural integrity the LS1 design does - hence it cannot take NEAR the power increase on stock internals. No way will it put 500 to the wheels without a complete and expensive redesign.
Boost is the way to go... you increase your effective displacement while boosting, then back to normal when not boosting. THose extra cubes only do you good at full power - at anything other than WOT, you're wasting energy and getting worse fuel economy...
As for truck pulling... errr, it's OK I guess. My daily driver has 260,000 miles on it and puts out 600 ft-lbs at the wheel, on the same Mustang dyno Parish is headed for this weekend. Duramaxes are OK (better than the 6.0PSD) but when they start catching the Cummins trucks at the truck pulls, then we'll call it the King... it should be noted that this year, the Duramaxes often ended up in the top three at the major midwest pulls, so I give it some credit. But it isn't the greatest thing in the world. That title is reserved for the Cummins!!!
Go ahead and build that 8.1, if it puts out more than 600 ft-lbs at the wheel, I'll tip my hat to you!
-scott
Boost is the way to go... you increase your effective displacement while boosting, then back to normal when not boosting. THose extra cubes only do you good at full power - at anything other than WOT, you're wasting energy and getting worse fuel economy...
As for truck pulling... errr, it's OK I guess. My daily driver has 260,000 miles on it and puts out 600 ft-lbs at the wheel, on the same Mustang dyno Parish is headed for this weekend. Duramaxes are OK (better than the 6.0PSD) but when they start catching the Cummins trucks at the truck pulls, then we'll call it the King... it should be noted that this year, the Duramaxes often ended up in the top three at the major midwest pulls, so I give it some credit. But it isn't the greatest thing in the world. That title is reserved for the Cummins!!!
Go ahead and build that 8.1, if it puts out more than 600 ft-lbs at the wheel, I'll tip my hat to you!
-scott
Nov 30, 2004 | 08:00 PM
#66
TECH Addict
Joined: Oct 2002
Posts: 2,544
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From: Mefis
The 572 uses a 10.2" Sportsman tall deck bow tie lock with a bore of 4.560" and a stroke of 4.375". It is a taller deck height block than the 8.1L. The 8.1L is essentially a stroked 454 with better heads and induction system.
If GM is still using the 6.135" bbc con rod, then the pin height on the 8.1L would be 1.48"
Cummins rules.
If GM is still using the 6.135" bbc con rod, then the pin height on the 8.1L would be 1.48"
Cummins rules.
Nov 30, 2004 | 09:42 PM
#67
On The Tree
Joined: Jan 2004
Posts: 133
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From: Omaha, NE
Originally Posted by greentahoe
That really is some good info!!! Is this due to what the other person stated having to deal with the pin location in the piston?? Could this have something to do with the reason for whipple including the intercooler with the 8.1 kit and not the LSX based kit?? The pistons are weaker and thus have an even lower threshhold for standing up to occasional detonation??
I will see this guy in the next week... I will ask him specifically what he is talking about. His experience is with marine versions of the motor and supercharged applications...
One day I saw him with two large complete motors, in crates, in the back of his pickup truck. I asked him what they were from, he said they were big block GM motors out of delivery trucks (high mileage stop & go abused), he got them as cores for a few hundred apiece and either sold parts, or ??? with them. They had different heads than any 454, 572, etc. that I'd ever seen from older trucks, he said they were the big block versions of the LS1 but were nowhere near as popular with the hot rodding crowd. (I don't mean to diss the motor with secondhand info, but I promise as soon as I see him I will ask for more details). We talked about some of the turbo cars running around town and definitely knew his stuff...
Nov 30, 2004 | 09:44 PM
#68
On The Tree
Joined: Jan 2004
Posts: 133
Likes: 0
From: Omaha, NE
Originally Posted by Bryan TTM
is it weak in the webbing or saddle area?...gonna chunk the rotating assembly anyway...or sell it on ebay...or maybe just send it back, its still in the crate
CHeck on some of the marine boards, maybe? Arizona Speed and Marine? LIke he said above, it's a Mercruiser I/O sterndrive motor that replaced the old big blocks (454, 502 they even offered a 454 from the factory with a roots blower).
-scott
Dec 1, 2004 | 06:32 AM
#70
TECH Apprentice
Joined: May 2004
Posts: 330
Likes: 0
So according to dieselgeek this engine should not last more than 5min.
http://www.azspeed-marine.com/sise600ho535.html
Chevy High performance mag(Jan 2005 issue Page 56), just did a build of 496 stroker, dynoed at 625hp at 6200 rpm all N/A, that has 2-bolt mains and Cast steel crank shaft. Since its not built like the LS1 bottom, it should been in little pieces by now. Same issue, they took their test mouse(S/C 355) and made 760hp at 6500 rpm. And that has 4bolt mains. What gives??? How come bottom ends are not blowing up??? they don't have ls1 style bottom end.
I believe that the 8.1 bottom end is the same as a later 454(502) block. Just the top end is different and Firing order.
One more thing, The cummings regin will be over next season. The ERA of the big charger Duramax has begun!!! Yeah I don't care for diesels but can't resist chevy power laying down the law. I know of three guys personaly that are building and fiting big turbos to the duramax.
http://www.azspeed-marine.com/sise600ho535.html
Chevy High performance mag(Jan 2005 issue Page 56), just did a build of 496 stroker, dynoed at 625hp at 6200 rpm all N/A, that has 2-bolt mains and Cast steel crank shaft. Since its not built like the LS1 bottom, it should been in little pieces by now. Same issue, they took their test mouse(S/C 355) and made 760hp at 6500 rpm. And that has 4bolt mains. What gives??? How come bottom ends are not blowing up??? they don't have ls1 style bottom end.
I believe that the 8.1 bottom end is the same as a later 454(502) block. Just the top end is different and Firing order.
One more thing, The cummings regin will be over next season. The ERA of the big charger Duramax has begun!!! Yeah I don't care for diesels but can't resist chevy power laying down the law. I know of three guys personaly that are building and fiting big turbos to the duramax.
