Posted By: Chargervic
68 Charger 451 engine build 25 MPG and 515 HP - 12/19/12 06:23 AM
I was asked on another page on the site to post this essay in the performance section. I hope it is useful and informative.
Specifications for the build of my 451” B block engine which delivers 25 MPG and pushes the 3975 lb Charger into the 11’s.
First of all, keep in mind that my mileage claim is for Imperial gallons, which we use in Canada. For US gallons (smaller by 20%), the number would be 20 MPG.
Another note is that I have had many years experience building Mopar hot rod engines and although I don’t have any magic, I do use a great attention to detail in machining and assembly.
I first built this engine in 1999, using a 400 block, 440 modified steel crank with reduced main journals, stock forged 440 rods highly prepped, 452 motorhome heads ported and polished with oversize valves and a Mopar 284º hydraulic cam. The intake was an old 383 Torker and the carb was a stock 1968 440 AVS Carter. After a couple of upgrades to an MP 284º solid lifter cam and a Six Pack set-up, I swapped the 727 transmission to a full manual shift 518 with lockup converter. This package got me into the mid 12’s and around 22 MPG.
After a few years and 30,000 miles of listening to the tappet clatter from the MP solid cam, I decided to go to a hydraulic roller cam and aluminum heads. After 40,000 miles of 7200 RPM shifts, I replaced the bearings, but left the rings and cylinder walls alone. Another reason for this upgrade is that I am running a 518 overdrive trans and most of the time the engine is below 2000 RPM, so I wanted much more bottom end torque and, believe me, this engine has it. Over 600 lb/ft from 2000 up to 4000 RPM.
Pretty much matches my Cummins diesel.
Here is the current engine I have now:
Compression ratio: 10.55:1
440 Source Stealth heads with mild port work, 84 cc chambers
Comp hydraulic roller cam, grind # XR274HR-10, Part # 23-710-9
Hughes Hydraulic roller lifters
Speed-Pro aluminum roller rockers (from 1999 build)
Smith Bros pushrods
Arias flat top forged pistons (custom from 1999 build)
440 Source fluid damper
Melling HV oil pump with ½” pickup and 7 qt pan (homebuilt) from 1999 build
Factory 440 Holley Six Pack carbs ( center carb jetted down to 62’s)
Edelbrock 383 style Six Pack intake
440 Source aluminum water pump and housing (modified)
The engine is all done at a little over 5000 RPM, so I use that as a shift point. It idles at 750 RPM in gear and gives 12+ inches of vacuum with a slightly rumpy idle. I have Hedman headers ceramic coated (from 1999) and a full 3” exhaust system front to back that I built myself. I use Dynomax mufflers and 3” glass packs as resonators in the tailpipes. The rear end gears are 3.91:1 Sure-Grip in an 8 ¾ housing. The car weighs 3975 with me in it at the track.
My little carb secret for mileage is simple. I put an electrically operated vacuum solenoid (minivan purge valve) in the vacuum signal line from the center carb to the outboards. I shut it off (no outboard carb action) for 99% of my driving and only use the outboards for the odd chebbie or phord that needs a lesson. I just recently dynoed another almost identical engine and we made 405 HP on the center carb only. This is lots for street use.
I use a Jacobs Ignition system from 2001, they don’t make them this good any more. Plugs are gapped at .055”. Champions, of course. I can run on 91 octane on the street, but use 94 at the track just to make sure there is no detonation, as I couldn’t hear it if there was. I run through the mufflers, but the noisy chebbies are pretty loud. If anyone has more questions about this set-up, please contact me through the site and I would be pleased to answer.
Specifications for the build of my 451” B block engine which delivers 25 MPG and pushes the 3975 lb Charger into the 11’s.
First of all, keep in mind that my mileage claim is for Imperial gallons, which we use in Canada. For US gallons (smaller by 20%), the number would be 20 MPG.
Another note is that I have had many years experience building Mopar hot rod engines and although I don’t have any magic, I do use a great attention to detail in machining and assembly.
I first built this engine in 1999, using a 400 block, 440 modified steel crank with reduced main journals, stock forged 440 rods highly prepped, 452 motorhome heads ported and polished with oversize valves and a Mopar 284º hydraulic cam. The intake was an old 383 Torker and the carb was a stock 1968 440 AVS Carter. After a couple of upgrades to an MP 284º solid lifter cam and a Six Pack set-up, I swapped the 727 transmission to a full manual shift 518 with lockup converter. This package got me into the mid 12’s and around 22 MPG.
After a few years and 30,000 miles of listening to the tappet clatter from the MP solid cam, I decided to go to a hydraulic roller cam and aluminum heads. After 40,000 miles of 7200 RPM shifts, I replaced the bearings, but left the rings and cylinder walls alone. Another reason for this upgrade is that I am running a 518 overdrive trans and most of the time the engine is below 2000 RPM, so I wanted much more bottom end torque and, believe me, this engine has it. Over 600 lb/ft from 2000 up to 4000 RPM.
Pretty much matches my Cummins diesel.
Here is the current engine I have now:
Compression ratio: 10.55:1
440 Source Stealth heads with mild port work, 84 cc chambers
Comp hydraulic roller cam, grind # XR274HR-10, Part # 23-710-9
Hughes Hydraulic roller lifters
Speed-Pro aluminum roller rockers (from 1999 build)
Smith Bros pushrods
Arias flat top forged pistons (custom from 1999 build)
440 Source fluid damper
Melling HV oil pump with ½” pickup and 7 qt pan (homebuilt) from 1999 build
Factory 440 Holley Six Pack carbs ( center carb jetted down to 62’s)
Edelbrock 383 style Six Pack intake
440 Source aluminum water pump and housing (modified)
The engine is all done at a little over 5000 RPM, so I use that as a shift point. It idles at 750 RPM in gear and gives 12+ inches of vacuum with a slightly rumpy idle. I have Hedman headers ceramic coated (from 1999) and a full 3” exhaust system front to back that I built myself. I use Dynomax mufflers and 3” glass packs as resonators in the tailpipes. The rear end gears are 3.91:1 Sure-Grip in an 8 ¾ housing. The car weighs 3975 with me in it at the track.
My little carb secret for mileage is simple. I put an electrically operated vacuum solenoid (minivan purge valve) in the vacuum signal line from the center carb to the outboards. I shut it off (no outboard carb action) for 99% of my driving and only use the outboards for the odd chebbie or phord that needs a lesson. I just recently dynoed another almost identical engine and we made 405 HP on the center carb only. This is lots for street use.
I use a Jacobs Ignition system from 2001, they don’t make them this good any more. Plugs are gapped at .055”. Champions, of course. I can run on 91 octane on the street, but use 94 at the track just to make sure there is no detonation, as I couldn’t hear it if there was. I run through the mufflers, but the noisy chebbies are pretty loud. If anyone has more questions about this set-up, please contact me through the site and I would be pleased to answer.
