My intention was to convert the GTX to a nice streetable driver running affordable pump gas but be a ground pounding, tire shredding monster at my whim. I investigated roots style superchargers, then the belt driven Paxton and Procharger style superchargers. I finally investigated Turbo charging. After taking several weeks to investigate all three I called Frank. I invited him over to have a few barley pops and to shoot the shit about my ideas on a few changes for the GTX that winter. Frank came over and I handed him a barley pop. He stood quietly as I started spewing what I had researched over the last several weeks and my grand ideas for changes to the GTX. We talked about the roots style superchargers and together came to the conclusion they definitely work, has a lot of bling, but it takes horsepower to turn those big roots style superchargers. We then chatted about the belt driven Paxton and Procharger style superchargers and concluded that would be a much better fit. Both Paxton and Procharger have kits available for my B-body Mopar and they’re an easy installation. The power levels are adjustable on both belt driven style superchargers with a simple pulley change.
However, I was looking to change power levels from mild to wild at a whim. Those belt driven Paxton and Procharger superchargers like the Roots style superchargers would require us to change pullies to make more power.
We opened a couple more barley’s and started talking Turbos. We concluded that turbocharging for the most part was free horsepower seeing you are getting power from waste. A turbo setup sure isn’t going to be the easiest project or for that matter the cheapest. However, it fulfills my requirements of mild to wild at a whim using a boost controller to change power levels.
OK, Turbo charging it is.! But how many, One or Two? And where to mount the turbo or turbos?
We had already added front tubular supports to the engine compartment limiting room for turbo charging. The gas tank was removed years ago and replaced with a fuel cell in the spare tire tub. This left a void where the gas tank used to be. Yep, that’s the place. Ok how many, one or two? After reviewing the room available we decided on two smaller turbos. Our thinking was they would spool faster and being installed in the rear we figured that would be a good thing. Also using two turbos we should still be able to achieve the 14 lbs of boost we are looking for. An added bonus and a huge cost savings with the rear mounted turbos is, we can use a standard set of headers and not have to pay for a expensive set of those custom built ones.
Our conversation then turned to intercoolers. We talked about air to air intercoolers like the one Franks son in law is using. Water to air intercoolers like Tim has in his Swinger. Then we talked about methanol injection as an intercooler. Methanol injection systems can be programmed to start and stop at given boost levels and actually acts as an octane booster. Using methanol injection will allow us to run more timing as well as more boost. Windshield washer fluid is cheap, you can get it almost anywhere. Frank and I pondered over the fact that maybe this setup wouldn't require an intercooler seeing the turbos are going to be mounted in the rear and the boost charge will have time to cool on its way back to the front. Well, we’ll come back and look at intercoolers after we get the build done and see how hot the boost charge actually is.
How are we going to oil the turbos? This issue was investigated for weeks. We looked at building a complete stand alone sump system and locating it in the trunk with a cooler venting outside. This type of system would require two pumps, a sump tank and an oil cooler. One pump for supplying the turbos with oil and one to scavenge the oil and return it through the cooler to the sump. I searched the web for days looking for pumps to supply oil at 60 psi as well as scavenge pumps that could return the volume that a #6AN line at 60 psi would create. What we decided to do was pull the oil off the back of the engine where the oil pressure sending unit would go. This is where most of the turbo setups on the market today are acquiring the turbo supply oil. Now with that decided, how are we going to get all the oil back to the engine? I found a scavenge pump that was designed for pumping oil in high heat conditions like rear turbo oiling or road race rear end gear lube coolers. The pump we purchased is made by Mocal and can handle constant temperatures up to 350 degrees Fahrenheit or 178 Celsius. It’s good for 10,000 hours of continuous use before any rebuilds and is made out of all metal components.
What about the exhaust? Aluminumized or Stainless tube? What size tube? We took an educated guess on the size and decided on 3 inch. We are building this system in sections that are removable via marman clamps so we can always decrease the main straight tube from the headers to a smaller size if the turbos won't spool fast enough. Well, that was our thinking anyway. We selected stainless for the exhaust do to the fact it will hold the exhaust heat in better than aluminumized thus helping with turbo spool up. When the exhaust is all completed, exhaust wrap will be incorporated from the headers to the turbos.
Ok, how about the boost return tube? Aluminum or Stainless and what size? Most turbo systems on the market supply aluminum charge tubes in their kits in the 3 inch diameter range. I had reservations that aluminum would oxidize over the years and I didn't want to blow that oxidation down through the carburetor into the engine. I figured stainless will never corrode thus removing any chance of contaminants in the boost tube. What we don't know is how hot the boost charge will be in stainless over the aluminum. So, stainless was selected for all the underneath car tubing over aluminum. The 3 inch charge return tube diameter was an educated mathematical formula I had the engineers at work help with.