Review: LC Engineering Header for Toyota 3RZ Short Cuts

| 4Runner Section | Toyota Reviews | Toyota Section |

By: Jeff Moskovitz - 1/2003

Background and Exhaust Manifold Cracking

Over the summer of 2002, my wife and I purchased a 1998 2.7 liter, 5 speed, 4x4 4Runner to serve as our family mover and daily driver. Frankly, I was hoping to find a 3rd generation 4Runner 4x4 with the 5 speed/V6 combo, but 3rd generation manual transmission 4Runners of any type seemed to be in short supply in our area, so when I found a good deal on a four cylinder/5 speed model, I jumped on it. I'm glad I did, as it has proven to be a capable and reliable vehicle.

The four cylinder motor that Toyota used in both the 3rd generation 4Runners and Tacoma trucks is the DOHC 3RZ, which in stock form produces a max of 150 hp at the flywheel and 177 ft. lbs of torque, or about the same as the 3VZE V6 motors used in the second generation 4Runners and pre-Tacoma trucks. Given the weight of the 4Runner, this translates into acceptable performance, but even when coupled with the manual transmission and 4.56:1 gears, the stock performance can hardly be called exciting. Taking into account the increased weight of the 3rd generation 4Runners, I would say that the stock performance is probably comparable to that of the 22RE used in the first generation 4Runners: it isn't a total dog, but it won't set your heart racing, either.

The 3RZ is a great truck engine, but user feedback has confirmed one common problem: the stock cast exhaust manifold is prone to cracking, especially between the #2 and #3 exhaust runners.

Cracked 3RZ manifold More detail of crack Full detail of crack

Because of the placement of the factory heatshield, many 3RZ owners may not be able to see if their exhaust manifold is cracked. If you have a 3RZ motor in your Tacoma or 4Runner, you should definitely take a few minutes and remove your heatshield and take a look at your manifold as you may be due for some corrective action yourself. (Note that you will also need to remove the intake crossover tube to access the heat shield.) In my case, however, there was no doubt: I could see a large crack through one of the heat shield's access holes, and I could hear the effects of the crack each time I started my engine. It wasn't going to heal itself, and left unchecked it would probably burn up an exhaust valve, so something had to be done.

Anyone who has followed my turbo truck project knows that I hate replacing stock parts with stock parts when better performing parts are available. Since several companies make exhaust headers for the 3RZ, I decided to see what was available for my 4x4 4Runner. My requirements were that the header had to fit well, be well constructed (preferrably from stainless steel), and be approved for street use by the California Air Resources Board (C.A.R.B.). That's not a long list, but after sorting through the various headers that are being produced for this motor there was only one that met all of these requirements: the 3RZ header made by L.C. Engineering (p/n 14-1731).

For anyone considering a header for the 2RZ/3RZ (in either a Tacoma or a 4Runner), here are all of the choices of which I am aware, smog-legal and otherwise. Note that few of these are available for all vehicle, drivetrain and transmission combinations. Generally speaking, 2WD Tacomas with manual transmissions have the greatest number of choices, and 4WD 4Runners with automatic transmissions the fewest. Call each manufacturer, or consult their web site or catalog to see if they make something for your specific vehicle/drivetrain:

Manufacturer: Notes: Picture:
Downey Off-Road
  • CARB approved
  • Mild steel construction
  • 4-to-1 design
Photo courtesy of Downey Offroad Products
E. L. Prototypes
  • Not CARB approved
  • Stainless steel construction
  • TRI-Y design
Photo courtesy of E.L. Prototypes
Northwest Off-Road
  • Not CARB approved
  • Mild steel construction
  • TRI-Y design
  • Will NOT fit 4Runners due to interference from passenger side frame rail
Photo courtesy of Northwest Off-Road, Inc.
L. C. Engineering
  • CARB approved
  • Stainless steel construction
  • Long runner 4-to-1 design
Photo courtesy of L.C. Engineering

As I stated, I wanted something that was CARB approved, stainless steel, and would fit my manual transmission 4Runner. L.C. Engineering's header for 4x4 Tacomas and 4Runners (p/n 27-1431) met all of these objectives. At $295 it was hardly cheap (although still cheaper than some of the other 3RZ headers), but it was the only header that had all of the features I wanted.

I ordered the header through TCR Automotive & Performance. The header arrived promptly and was well packaged. In addition to the ceramic coated stainless steel header, the header kit also included a new factory steel exhaust gasket, factory "donut" gasket, two O2 sensor gaskets, and a bag with new bolts and nuts for mounting the O2 sensors and bolting the header to the catalytic converter.

For a Tacoma, this is all you will need, as the header is designed to bolt to the front of the stock Tacoma catalytic converter. However, because the 4Runner uses a single-piece cat and downpipe, you cannot bolt the header directly to the front of the cat -- there's no flange there, just welded pipe. Consequently, 4Runner owners must either have the stock downpipe removed from the cat and a stock-style two bolt exhaust flange welded in its place, or must replace the cat completely with a new, properly flanged cat (either from a Tacoma or from LC Engineering, which makes a bolt-on 17 5/8" X 2-1/4" high flow cat for this application, p/n 14-8239). I don't know why Toyota made the Tacoma and 4Runner different in this aspect, but it was probably done to save money at production time. If you own a Tacoma, consider yourself lucky, as your 4Runner owning cousins will have to pay a bit more to get the job done.

Quality and Fit of the Parts

Keeping in mind that this is a $300 header and not a $600 header, I think the quality of the kit is very acceptable. By far, the two most important things to consider when purchasing any header are:

Never underestimate the importance of a properly fitting header! When purchasing a header, every other consideration, including performance, is secondary to the "Will it fit?" question! Happily, I can report that the LC Engineering 3RZ header fit with absolutely no interference problems. None! I've installed a half dozen or so headers over the years, including LC's big dollar 22RE turbo header (also reviewed on this site), and this is a first. Give LC Engineering an "A+" for fit.

However, even though the header fits fine and looks sturdy, there are still a few aspects of its construction that could use some improvement, in my opinion.

All that Glitters is not Stainless Steel!

When a part is described as being constructed of stainless steel, I assume that means the whole part is made from stainless steel, not just some of the part. So I was a little disappointed to discover that LC's "stainless steel header" is, in fact, only partially constructed from stainless steel: while the runners are made from stainless steel, other components of the header are made from the more common (and less durable) mild steel. Non-stainless parts include the header flange, exhaust flange, O2 sensor mounting bosses/tubes, and the merge collector itself. These conclusions are based on magnetic attraction. Stainless steel is much less magnetic than mild steel, so running a simple magnet over a header will reveal which parts are constructed of what material, something otherwise hard to do when everything is painted or coated in ceramic. Because the runners are subject to the most heat and all parts are ceramic coated, this is probably not much of an issue from a durability standpoint, but in my opinion a header described as "stainless steel" in the catalog should be 100% stainless in its construction unless otherwise noted. In my opinion, LC should be more candid about the actual construction of its products, and use a phrase like "partial stainless steel construction" or "critical components constructed of stainless steel" to prevent any misunderstandings.

All Merge Collectors are NOT Created Equally!

The crimped merge collector. LC Engineering's ProMerge collector.

Even more disappointing than the mixture of stainless and mild steel is the crudely crimped tube that serves as the header's merge collector.

For those that are unfamiliar with exhaust header design, the merge collector is where the two, three, or in this case four exhaust runners are joined together. The merge collector is one of the critical areas of any header, and ideally the merge collector will join the exhaust runners as smoothly and evenly as possible. The purpose here is three fold: to join the runners to the rest of the exhaust; to prevent exhaust gas reversion (exhaust gasses entering into a different exhaust runner or cylinder instead of exiting the system); and to create enough "pull" as the exhaust gasses flow through the collector that a vacuum is created in adjoining runners, and gasses from those runners are literally sucked out as they leave the cylinder head. A properly designed and executed merge collector is a thing of beauty.

Unfortunately, the LCE 3RZ header's merge collector is executed in a crude manner. The four exhaust runners enter the top of the collector rather suddenly, and no effort is made to blend the entering tubes; they just dump into a common space with a hole at the other end. Where a top quality collector uses welds and smooth transitions, the LCE header uses a simple stamped/crimped tube that accomplishes the primary task of joining the runners to the rest of the exhaust but makes no special effort to perform the secondary tasks of anti-reversion and/or gas extraction.

Is this a fatal flaw to this header? No, and I certainly didn't return it because the merge collector was ugly... but I would have paid more for something better such as the ProMerge collector, especially since LC prices it at a paltry $50.

It seems to me that if I'm already willing to pay $300 for a header that may add 5 peak horsepower to my motor's performance, why not charge me an extra $50 and include a component that could increase that power output by another 1-4 horsepower while further broadening the powerband? I would have added the "Pro" merge collector myself, but the header comes with a ceramic coating that I didn't want to disturb, so the purchaser is stuck unless they want to remove and reapply the ceramic coating themselves. Grrrrr... Give LC Engineering a "C-" on the merge collector.

Nuts and Bolts

Finally, I need to mention one additional gripe regarding this kit: the bolts supplied to join the header to the cat are just not meaty enough, and need to be larger in diameter. If you buy this kit, I recommend upgrading the header-to-exhaust bolts to 1/2" or 9/16" in diameter. This is especially true if you have a 4Runner and are using LC's properly flanged high flow cat. The holes on the flange of LC's cat are even bigger than the holes on the header exit flange, and the bolts supplied with the header practically fall through the holes in the cat flange; they will do the job in a pinch, but bigger would be better. Give LC Engineering a "C" on the quality of the supplied hardware.

Installation

The completed installation.

The installation is very straightforward, and because this is a review and not a how-to article, I won't go over all of the steps here. Basically, you remove the stock manifold and replace it with the header. There are no surprises. If you are unsure how to remove the stock exhaust manifold, consult a factory service manual or a Chilton's or Haynes manual.

A few tips:

The entire operation took me approximately five hours, from removing the stock parts to test driving the finished job. This sounds like a long time, but I also removed the stock exhaust in its entirety and installed a new catalytic converter and cat back exhaust, which will be described in the next installment. I would estimate that the header itself could be installed in 1 - 2 hours, depending on your skill.

Driving Impressions

Another view of the completed installation.

In addition to installing the header, I also replaced the complete stock exhaust with a new JBA 2-1/4' mandrel bent stainless steel cat back exhaust, KandN 'wide open'-style muffler, and high flow LC Engineering/CarSound catalytic converter. All of these exhaust changes were performed at the same time, and the additional mods will be described in Part II of this series.

I have to say that the improvement is very noticeable: where the 4Runner used to run out of steam at around 4000 rpm it now revs to 5000 rpm (and after doing the deck plate mod, it happily revs to 5500 rpm!) I have a particularly steep hill near my house, one that I routinely have to downshift into first gear to climb. I used to have to slog up this hill, but I can now charge up, happily accelerating all the way to redline if I choose. The performance improvement is BIG, and makes me very happy that I spent the money on these modifications.

A few days after I installed the exhaust, I took my family on a trip over the Sierras to visit my in-laws. When we did this same trip in the fall, performance/acceleration was mediocre, and I was very reluctant to pass other vehicles unless I had lots of room for acceleration (this is on a grade at approx 3000ft.-7000ft. of elevation). Following the exhaust installation, performance and acceleration over this same route improved significantly. Even loaded down with a skis and a week's worth of luggage, we could easily climb and pass other vehicles on grades, things I couldn't do before.

People always want to know numbers, but unfortunately I only have seat of the pants impressions. Overall, I would estimate that the combination of these various mods (header, exhaust, cat, and deck plate) has resulted in an increase of 6-8 (or more) rear wheel horsepower at peak torque, but even more impressive than the increase at peak torque is the overall improvement to the power band, which starts at around 2700 rpm and goes all the way to redline (5500 rpm). DOHC engines need to breathe, and I am convinced that Toyota put some serious restrictions on this motor's performance in an effort to keep things quiet (and thus acceptable) for the typical "soccer mom". With the restrictions removed, the motor reveals itself to be a very-smooth-yet-powerful force to be reckoned with.


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