Rebuild 454 carbs with high compression pistons
07-02-2019, 05:23 PM
#1
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Rebuild 454 carbs with high compression pistons Hello,
my current 454 engine jamed, looking for rebuild kit most properly will be :
main bearings and connecting rod @0.10
pistons and rings @0.30
it is possible to install high compression pistons to improve performence and more fuel efficeny ? Or if i go high compression i need to upgrade something else along with that ?
my current 454 engine jamed, looking for rebuild kit most properly will be :
main bearings and connecting rod @0.10
pistons and rings @0.30
it is possible to install high compression pistons to improve performence and more fuel efficeny ? Or if i go high compression i need to upgrade something else along with that ?
07-02-2019, 05:53 PM
#2
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LOL ,,,, 454 and economy in the same sentence.. 
New pistons, cam etc,, you'll need to tune..
ASSUMING this is a street vehicle,, if its dedicated track,, IGNORE~~
Honestly almost ANY EFI setup out there will kick the carbs butt for economy, and overall drive-ability,,
you can wangle more peak power with a carb if the engine is built for it,, but,,
Carbs and Ethanol + overly cocktailed up pump gas means your handicapped
right out of the box with a carb, they just dont build as good of a fuel fog with all the
anti VOC ingredients plus the alcohol in the fuel.
Biggest reason race fuel is easier to tune power out of is the evaporations rate and
the lack of stuff to keep the fuel liquid. (MTBE ish chemicals)
The EFI system would allow you to tune closer to the edge of knock than the
carb so that's where the economy comes in, which would allow you to run
higher compression with less effort.
I own carbed vehicles,, love the sound, but my rig for road trips has EFI.
There is a reason all the Gen 4 and 5 V8s make the power they do stock.
New pistons, cam etc,, you'll need to tune..
ASSUMING this is a street vehicle,, if its dedicated track,, IGNORE~~
Honestly almost ANY EFI setup out there will kick the carbs butt for economy, and overall drive-ability,,
you can wangle more peak power with a carb if the engine is built for it,, but,,
Carbs and Ethanol + overly cocktailed up pump gas means your handicapped
right out of the box with a carb, they just dont build as good of a fuel fog with all the
anti VOC ingredients plus the alcohol in the fuel.
Biggest reason race fuel is easier to tune power out of is the evaporations rate and
the lack of stuff to keep the fuel liquid. (MTBE ish chemicals)
The EFI system would allow you to tune closer to the edge of knock than the
carb so that's where the economy comes in, which would allow you to run
higher compression with less effort.
I own carbed vehicles,, love the sound, but my rig for road trips has EFI.
There is a reason all the Gen 4 and 5 V8s make the power they do stock.
Last edited by pdxmotorhead; 07-02-2019 at 06:07 PM.
07-02-2019, 11:21 PM
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Hey thanks for the reply, i wont call it economy no bbc is economy im saying better efficiency. Not looking to go high perfermence. Yes it is street, as im overhauling the engine im checking the possibity to gain more horse power on the stage
07-03-2019, 07:44 AM
#4
I see you profile says you're in Dubai, are you? What is the fuel like over there, I 100% get where PDX is coming from, but if ya'll have more "pure" gasoline that that watered down **** we get in the states, you can make some stuff happen most likely. What kind of vehicle is this in, and intended use?
07-04-2019, 03:00 AM
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Hello, thanks for the reply
yes Dubai, we have 3 types of fuel:
98 octane
95 octane
91 octane
truck is 1977 c10 4x4 transmission TH400
my concern is as long as im rebuilding the engine looking to do improve the performence comparing to the stock pistons. As i dont have much experience with GM engines but i do. Have with NISSAN TB48 engines its has differenct configuration for sure but the concept we follow if you have to rebuild your engine with bigger bore like my situation now 0.30 we do install high compression pistons without changing anything else its works perfectly with stock configuration only ecu tunning is required then you ready to go.
Can we do something like that on the 454 ?
yes Dubai, we have 3 types of fuel:
98 octane
95 octane
91 octane
truck is 1977 c10 4x4 transmission TH400
my concern is as long as im rebuilding the engine looking to do improve the performence comparing to the stock pistons. As i dont have much experience with GM engines but i do. Have with NISSAN TB48 engines its has differenct configuration for sure but the concept we follow if you have to rebuild your engine with bigger bore like my situation now 0.30 we do install high compression pistons without changing anything else its works perfectly with stock configuration only ecu tunning is required then you ready to go.
Can we do something like that on the 454 ?
07-04-2019, 03:54 AM
#6
TECH Addict
If its all stock, you'll gain power with the higher compression pistons, yes.. to a point
But to really get anything you'll need at least a new cam and lifters.
But,, the 454 from that vintage is way way way down on power,, they made as little
as 250HP. 1976/77/78 probably the lowest HP big blocks made. horrible cam,
often had restrictive heads that would not let them rev.
Depending on your budget and needs ,,
Heads/Intake/cam/lifters are going to be needed to really see much improvement.
There are several distributors in the US that sell crate engines that at the end may be the best price performance option.
But to really get anything you'll need at least a new cam and lifters.
But,, the 454 from that vintage is way way way down on power,, they made as little
as 250HP. 1976/77/78 probably the lowest HP big blocks made. horrible cam,
often had restrictive heads that would not let them rev.
Depending on your budget and needs ,,
Heads/Intake/cam/lifters are going to be needed to really see much improvement.
There are several distributors in the US that sell crate engines that at the end may be the best price performance option.
07-04-2019, 10:03 AM
#7
TECH Veteran
My 454 in my 97 gets 12 mpg loaded or unloaded. People look at me crazy when i tell them the 454 gets the same mileage as some 6.0 LS truck owners.
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07-05-2019, 02:19 PM
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07-05-2019, 02:22 PM
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If its all stock, you'll gain power with the higher compression pistons, yes.. to a point
But to really get anything you'll need at least a new cam and lifters.
But,, the 454 from that vintage is way way way down on power,, they made as little
as 250HP. 1976/77/78 probably the lowest HP big blocks made. horrible cam,
often had restrictive heads that would not let them rev.
Depending on your budget and needs ,,
Heads/Intake/cam/lifters are going to be needed to really see much improvement.
There are several distributors in the US that sell crate engines that at the end may be the best price performance option.
But to really get anything you'll need at least a new cam and lifters.
But,, the 454 from that vintage is way way way down on power,, they made as little
as 250HP. 1976/77/78 probably the lowest HP big blocks made. horrible cam,
often had restrictive heads that would not let them rev.
Depending on your budget and needs ,,
Heads/Intake/cam/lifters are going to be needed to really see much improvement.
There are several distributors in the US that sell crate engines that at the end may be the best price performance option.
will this
https://www.summitracing.com/parts/sdm-pce281-1488/
or this
https://www.summitracing.com/parts/s.../?tab=Overview
would be a good option ?
I have no clue regarding the calculations of choosing heads/ compression/ pistons and sizes
is there anywhere or anyone can advise or help me with that ?
Last edited by ALMARRI; 07-05-2019 at 02:33 PM.
07-31-2019, 07:21 PM
#11
A lot depends on what machine shop services you have available, as well as what heads you have on there now. You say street use, then any head that came stock on a 454 can be made to put out some substantial power very easily. and right off idle to boot.
What is the casting number on the heads? Or do you have a pic of the intake ports?
As stated earlier, those motors stock were pretty weak. The main reason is they have super low compression. They are usually rated at 8 or 8.5 to 1 and really have 7...just slugs. Add to that a smog era timing curve and they feel pretty gutless.
I have built a few of these because they are cheap...stock large oval port castings with a trick valve job/bowl blend and 2.19 int/ 1.8 exhausts are well over 500hp.
What is the casting number on the heads? Or do you have a pic of the intake ports?
As stated earlier, those motors stock were pretty weak. The main reason is they have super low compression. They are usually rated at 8 or 8.5 to 1 and really have 7...just slugs. Add to that a smog era timing curve and they feel pretty gutless.
I have built a few of these because they are cheap...stock large oval port castings with a trick valve job/bowl blend and 2.19 int/ 1.8 exhausts are well over 500hp.