Fortunately, nowadays there is a vast offer of carbureted intakes for LS applications and luckily for many of us MSD Performance now offers an ignition controller which makes LS performance much more attainable for car worshipers that sticked on their tradition no matter what!
The question is , is it possible to add boost to a carbureted Ls?
It’s true that many of us want to add some boost to an Ls motor but in a way that our budget can offer.Its ok if you have enough cash ,so adding some boost wouldn’t be a problem at all!
To make this ‘’experiment’’ is used a waste, a 5.3L LM7
Working on this thing it nessecary to upgrade the things that are in an immediate need of it,for example the turbo kit ,intercooler & CSU carburetor
The team that worked on this changed the factory head gaskets & studs for Fel Pro & ARP units,also they kept the stocked stuff.Running just a little boost level ,the stock components were deemed more than adequate.
According to the team – ‘’Webought the iron block 5.3L for $300. Considering that the motor was with no transmission, harness or any other parts that usually come with it, wa of no importance to us since it was intended for the dyno use and carbureted dyno use at that. Later on, the oil was modified to a 5W-30 synthetic, the LM7 got itself a new electric water pump, 1 3/4-inch long-tube headers and the Edelbrock Victor Jr. intake. The intake was installed with a set of Fel Pro intake gaskets, to which we added a Holley 750 HP carburetor, and the MSD ignition controller. An Aeromotive fuel system was used to make sure that the right fuel was delivered in both normally aspirated and boost conditions. ‘’ they said
This 5.3 was never used so can you imagine when it fired up on the 1st crank of the starter& settled in a smooth idle with harsh oil pressure.
The 750 horsepower carburetor was featured with an external jetting system,that was especially done to make changes in air fuel a simple turn of the screw
But there was something to be concerned,the fuel distribution after the boost was added
They opted to perform the cam swap once and install and remove the turbo system, allowing them to run both the stock and mild Crane cams in NA & turbo configurations. Since they had the factory cam in place, on went the single turbo system from CXRacing.The kit was both simple and effective, consisting of dedicated tubular exhaust manifolds, a common Y-pipe to channel the exhaust to the single 76-mm turbo & a 3-inch down pipe. Also available we must add ‘not used’ was an air-to-air intercooler. On this low-boost application, the carburetor was acting as the intercooler. Having measured temperature drops across the carburetor exceeding 100 degrees on high-boost application, the team knew it would suffice on our mild turbo combo. The kit also included a dedicated wastegate set to provide 10 psi & since it was designed for an EFI application, they
sourced some additional tubing, silicone couplers and clamps from CXRacing to complete their carb kit.
When the swap was done they put the turbo system back together & ran the new configuration in boosted form. Adding the new Crane cam, the peak power jumped to 611 horsepower and 565 lb-ft at a peak pressure of 9.9 psi.But the swap neeted a gain of 84 horses & 45 ib-ft of torque.
And there were still many things to be concerned like how these enhancements under boost compare to the normally aspirated gains.Then the CXRacing turbo system came & on went the long-tube headers and 750 Horsepower carburetor.Wasn’t necessary to make changes to the carburetor but they did adjust the timing curve to provide the temperature of 32 degrees.
Upgraded with the Crane cam, the peak power numbers checked in at 411 horsepower & 393 lb-ft of torque. The power was actually still climbing at 6,000 rpm. In normally aspirated trim, the cam swap was worth 76 horsepower & 27 lb-ft of torque. This compares to 84 horses & 45 lb-ft of torque with the turbo. Then is time to put those theories on the nightmare test ,dyno test !
At the very end the results shows that it is doable to add a cheap, carbureted LS motor & to add boost to it as well. This goes to all of you with a limited budget. And don’t bother yourselves with complex or expensive EFI systems. Instead you can use an alternative fuel route & stick a carbureted LS under the hood of your old Camaro or Chevelle as well . And if that’s a little too little power go for a right carb & MSD controller, you can always add boost.
Is anyone going to try this ?
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