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[Samson]

As of September 2005, I'd had my truck for almost 5 years and the warranty was about to run out. My truck had had the TRD supercharger, TRD headers and TRD exhaust from the day after I bought it new, and I ran it that way, with no fuel mods, for almost 30,000 hard miles.

Then I started getting online and reading more and more about fuel mods that were necessary for peak performance and longevity of the motor and the widespread "pinging" problem with supercharged V6 Tacomas.

Now, my truck had never pinged, and I'm not sure if it was just the characteristic of my particular engine, or if it was because I drove it like a racecar and never was boosting at low RPMs in high gear. But in any case, I did do the fuel mods and contributed to the literature of the subject with my own ideas for electric fan installation and fuel pressure gauge installation and a low-cost governor defeat mod.

I added water injection and a 9-lb pulley to my truck and had it tuned, but the best it dynoed was something like 242 horsepower. It just wasn't enough for the time and effort I'd spent, so I started doing my own research.

[Samson]

What I had figured out after a few months of reading and experimenting and calling folks "in the know" was surprising. It is now my opinion that superchargers are a poor solution for increasing engine performance, for a number of reasons.

1. Most superchargers (like the TRD unit) are not intercooled. As air is compressed, it heats up. The more you compress it, the more it heats. The resulting heat I believe to be one of the main culprits behind the detonation that plagues most 5VZ-FEs, since the TRD S/C compresses air and then forces it directly into the engine. No intercooling is possible except for water injection which, in this application, I view as a band-aid of sorts.

2. Most superchargers are relatively inefficient when measuring how much the air is heated per degree of compression. Of course, the claim of inefficiency is relative to the performance of a turbocharger, which is the ultimate subject of this article.

3. While it may not seem important when considering making maximum power, fuel economy actually is a factor in a daily driver like my truck is to me. Superchargers, which are overwhelmingly belt-driven devices, ruin fuel economy with their characteristic parasitic drag. Turbochargers do a much better job of maintaining or even enhancing fuel economy when correctly sized and installed.

4. According to graphs published by Magnuson (the makers of the TRD supercharger) at wide open throttle redline and 7 lbs of boost, the TRD S/C draws over 18 horsepower just to run. At 9 psi, the loss is over 23 horsepower. And at 11 psi, the point at which the oversped TRD S/C is not so much compressing the air any longer as overheating it, the loss is nearly 29 HP! That's power that is deducted straight from the crank. Turbochargers do not suffer from these large power losses.

[Samson]

I built a spreadsheet to take all of these factors into account and the results were compelling.

Assuming a stock engine volumetric efficiency of 80%, a supercharger efficiency of 60%, a turbocharger efficiency of 74%, ambient temperature of 75 degree F, intercooler efficiency of 70%, and similar boost levels for both the supercharger and turbocharger, this is what I found:

At 7 PSI, 5500 RPMs, wide open throttle (WOT) the charged air as it is pumped into the engine from the S/C is 121 degrees F hotter than the intercooled turbo air. Futhermore, the S/C has drawn 18.2 horsepower to run itself.

At 9 PSI, the S/C is 140 degrees hotter and draws 23.4 horsepower.

At 11 PSI, the S/C is 157.5 degrees hotter and draws 28.6 horsepower.

At 12 PSI, the S/C is 166 degrees hotter and draws 31.2 horsepower.

What do these numbers mean comparatively?

Temperatures and drag loss, where T/C= Turbocharger, S/C= Supercharger, HP is horsepower and PSI is manifold boost pressure
PSI T/C S/C S/CHP
07 108 229 -18.2
08 111 241 -20.8
09 114 254 -23.4
10 117 266 -26.1
11 120 277 -28.6
12 123 289 -31.2
13 125 300 -33.8

(These numbers are based on my own calculations. They may not be accurate. The S/CHP numbers do not take into account horsepower losses from heat and less airflow due to expanded volumes of heated air.)

Once I was done with the spreadsheet, I knew I had to ditch my supercharger for a custom turbo setup.

[Samson]

The first thing I did was test my TRD exhaust to see if it would flow enough to support a turbo system. While the muffler was a good flow-through design, the exhaust itself was not up to the job. For some reason, TRD decided to use flanges with two holes instead of three, and I had problems with those flanges leaking the whole time I had the exhaust. Across my entire exhaust, Toyota and TRD had no less than 5 idiotic, leaky two-hole flanges. I really can't stand exhaust leaks, and there is no reason that a well-designed exhaust should ever leak.

Another problem was that the TRD cat-back piping itself was not of a large enough diameter. It was 2.5 inch, and I wanted three inch minimum.

To make matters worse, the stock catalytic converters were very restrictive. For starters, they are just 2-inch pipes. I drilled into my exhaust pipe before and after the cats and welded female NPT bungs to the holes. Then I screwed in a pressure gauge and went driving. What I found was that at 7 PSI boost, wide open throttle redline in 2nd gear, the stock cats made an 8 PSI backpressure restriction.

Much of that pressure was due to the cats themselves, but part of it was also due to the odd small-diameter pipes Toyota supplied on the Tacoma.

In my opinion, the catalytic converters are the most restrictive part of most factory exhaust systems, and people who buy cat-back exhaust systems without first identifying and rectifying the most restrictive parts of the exhaust system are literally throwing their money away. Just like I did, initially.

I was determined to solve that problem as well as eliminate any potential for leaks in my new system.

[Samson]

I decided to keep the TRD headers on the driver's side and designed a 3-2-1 manifold for the passenger side. The first thing I did was flame-cut a mild steel flange for the passenger side. I made it out of half-inch bar and ground the sides smooth and bored the mounting holes and exhaust holes and it fit perfectly.



I was able to test-fit it on a spare motor I have on an engine stand in my shop.

After a couple abortive attempts to make the manifold myself, I went to a professional and had it fabbed up. If you want to make a manifold that will last, you need to make it out of stainless steel (not 304) on a mild steel flange. This means you better have access to a plasma cutter and a TIG welder. It was the most time-consuming part of the project, as the manifold had to be hand-made which means pieced together. The manifold also had to have provisions for the Tial wastegate I used and the wastegate pipe that would have to join the downpipe.

The following shot shows the manifold from below, with the downpipe next to it. You can see all the small pieces of pipe that had to be cut and welded to make an extremely durable smooth-flowing manifold

[Samson]

Since I have a good hook-up for stainless steel tubing, I decided to have the entire exhaust made out of stainless steel. Since only the manifold itself can't be made out of 304 stainless, 304 was good enough for the downpipe and everything else in the exhaust.

I wanted it to be leak- and maintenance-free and I went searching for a solution to two-bolt flanges. What I discovered were V-band flanges and clamps. V-bands are the ultimate. They seal with a single nut that tightens a clamp around two machined stainless steel flanges. No gaskets are used, and the tighter you turn the nut, the tighter the clamp grips the flanges. They are really a great solution for leak-free sealing. The only downside is they are expensive (up to 80 bucks for the best set available). Here are pictures of the flanges welded onto the downpipe.




And here is the clamp, with the downpipe clamped to the exhaust.



You can kind of get an idea of how it works. That is one of two v-bands I used. The other connects the downpipe to the turbo, again, without a gasket. I highly recommend the use of v-bands...they are so worth it!

[Samson]

The rest of the exhaust is a single TIG welded piece, with a stainless flexpipe, two stainless 3-inch cats, a 3-inch Magnaflow muffler (stainless), and a 3-inch lipless downturn pipe- you guessed it. Stainless. I went with Magnaflow because they flow the best. The design in my opinion is far superior to the baffle-based Flowmaster design. And besides that, the Magnaflow sounds badassed. I bought it off Summitracing.com, and if you haven't used their search engine, you are missing out. Whoever coded their site deserves a bonus, because it is amazingly well done.

Back on topic, here's some pictures of my exhaust. Remember, this is all one straight piece with just a single leakproof v-band holding it to the downpipe:



Check out the crazy wheelie-bar muffler mounts my fabricator friend came up with!



As you can see, it all snugs up nicely under the truck, out of view from the street. The pipe empties under the truck so there is no pipe sticking out the back or side. I think it's a cleaner look and it avoids the necessity of making any restrictive bends to go over the axle. If you've gone mandrel and straightpipe this far, why muck it up now?



I wanted the downpipe to have the wastegate pipe join in fairly far down the downpipe itself, and to not impede flow out of the pipe. The wastegate pipe actually meets the main downpipe when the exhaust is already making a sweeping turn, and the wastegate pipe runs in the same direction as the exhaust is going. I believe this is a superior solution to just teeing in to the downpipe right behind the exhaust turbine outlet at 90 degrees to flow.

Here you can see it before and after installation:

[Samson]

I found an intercooler on Ebay that fit my truck perfectly. It's aluminum, bar and plate design, probably made in China, and it works great. Plus it was only $164, shipped!

I learned that bar and plate is much better than tube and fin, mostly because an intercooler is not so much a radiator as a heat sink. You want it to be a big chunk of aluminum, because the aluminum soaks up the heat generated during a boost event and then bleeds it off during normal driving. I can drive my truck pretty hard and then jump out and feel the tanks and the turbo side will be pretty warm but the engine side will still be quite cool. That means that heat is being dumped and cool boosted air is reaching the engine. I've also spent some time with my scan tool plugged in, watching the intake air temps as read by the MAF sensor. You have to boost hard from a dead stop, throughout the rev range, in the first three gears before you even start to see an increase in intake temperatures.



It fits exactly behind my prerunner bumper but it still gets plenty of airflow. You don't even notice it if you're not looking. I love sleepers! No one would suspect a lifted 4WD of this setup...

[Samson]

Since I was planning on going up to over 12 PSI, I used aluminum tube for my intercooler piping and used all-silicone 45s, ells, reducers, and humphoses for the connectors. Instead of welding or forming beads on all the piping, I bought stainless t-bolt clamps and installed them. They are supposed to have 10 times the clamping force of regular hose clamps.

As of yet, I haven't had a single one of them slip or work loose. I recommend them.




Silicone is a pretty good insulator, and I covered most sections of exposed after-intercooler aluminum with thermal exhaust wrap to keep out the heat.

[Samson]

No warning of a turbo:





This is the upper end of the installed downpipe, with a wideband O2 sensor bung welded in. Also, note the V-band clamp sealing the downpipe to the turbo.


The Tial blowoff valve makes some cool noises. Not too loud, but you know it's there. While cruising, the turbo makes a quiet whine like a jet engine. Until you stomp on it, heh-heh.




This is the MAF pipe I had made. It's mounted after the intercooler so it reads the air temperature after cooling but before water injection.


I had too many gauges and computers running off the plenum pressure signal, so I plumbed a few extras and all is working well.




Having had both a supercharger and a turbocharger on the same vehicle, I can say with certainty that I will take a turbocharger over a supercharger on any car or truck I own in the future.
Next up is installing a twin-turbo 6.1 Hemi in my 1968 Dodge Charger.

[Guest]

Very nice setup.

I would love to see how your manifold is laid out and hear about how you have fueled and tuned it.

Gadget

[Guest]

Wow. Very nice. You have done some extensive research. Any more info would greatly appreciated. Like Gadget asked, How are you fueling it? I will taking a couple ideas off of your set up and transferring it to mine, i.e. the clamps for your intercooler piping. Is there a way you can post a pic from the top-front of the motor emphasizing on the down pipe to the fire wall?

Sean

[Samson]

[Samson]

[3rdbro_ofsamson]

GADGET!! It is good to see you on this forum... hehe.

To all the folks that have not had the privilege of driving or being in this truck, this truck is BADASS!!!! Good Job BRUHAHA BRUTHER!!
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