Doug Thorley vs. LC Engineering

As far as I know, the only 6 cylinder headers LCE makes are for Gen 1's. If you do get DT's, make sure you get ones with O2 sensor bungs already on them so you don't need to pay more money to have them retrofitted.

 

Just updating my truck. I have the URD 2tr supercharger with Doug Thorley headers and my gasket blew and my header cracked. The DT headers are not made of the same strength steel as LCE headers. I am getting new LCE headers to replace my thorley headers. So if your truck has boost, the LCE headers are a better option. I will post my review of the difference once I get the new headers on my truck.

 

Good move. The LCE 2TR header is built like a tank and fits like a glove.





If I'm not mistaken, you're one of the first guys here (and maybe the only guy) with a force inducted 2.7. Would you mind posting some pics of it as well as perhaps a video of how it sounds?

 

I will try post a video when my truck is repaired. These are some old photos

 

All that black plumbing looks really badass.


And that would be great if you could post a video, as boosted 2.7's are so rare.


Greg

 

I called both Doug Thorley and LCE today... DT is CARB legal in California. The code is imprinted right on the header. I've chosen to go with DT and here's a few reasons why...

With equal length headers, as each exhaust valve in the head of the engine is opened and exhaust gas is forced out, it passes down one of the header pipes and through to the down pipe, where the exhaust gas velocity causes a slight vacuum in another header pipe. This has an effect of scavenging (extracting) exhaust gas from the cylinder, which is beneficial for performance. In our vvti engines, which have cam overlap, the scavenging (extracting) effect will pull air through from the intake manifold as well, further increasing performance. Extractor manifolds separate the gas that flows from the individual cylinders so that inter-cylinder interference is avoided and maintaining an optimum gas velocity dictated by the diameter of the tube. They also allow the individual cylinders to assist one another by means of the negative pressure waves generated at the collector, where the individual exhausts merge. The length of exhaust headers can be tuned to perform best at specific RPM ranges. For most trucks, the 4-2-1 design produces more mid range power with the sacrifice of top end power. Mid range power is great for the street since when you drive you usually do not rev your motor close to redline. Instead, you keep the revs somewhere in the middle, usually shifting at 2.5-4K, and this is where the headers shine. This is more the exception than the rule as most headers that are 4-2-1 do produce more power in the mid range, so the "seat of the pants" and "butt dyno" make these headers feel stronger since the power band isn't as high in the RPM range. The 4-1 headers are designed so that all 4 exhaust pipes merge into one. In most dyno tests, this produces the most top end power since it usually offers the best flow characteristics for the engine at high engine speeds. 4-1 headers usually move the power band up, which makes the bottom of the RPM band feel a bit weak and the "seat of the pants" feel might not be as strong as a 4-2-1 header. However, dyno tests have show that at low RPM there is very little difference in power. The 4-1 headers usually have less back-pressure than the 4-2-1 header and people say their trucks seem louder at high RPM with the 4-1 headers.

 

so how does the headers effect mpg. I have to downshift like 3-4 times on the highway when i go to my dads (which is ever weekend) so if they prevent the need for the tranny to downshift how much mpg would i gains. And sometimes it takes it forever to upshift. I have a 3rz seems like LCE is the way to go?

 

That's a good description of the theory... however the actual dyno test results show exactly the opposite.

A bone stock 2.7 has a torque peak of 133ftlb @ 3,800 rpms.

Doug Thorley header has a torque peak of 144ftlbs @ 4,000 rpms.



LCE header has a torque peak of 158ftlbs @ 3,150 rpms. (blue run)



The DT 4-2-1 short tube header raises the torque peak over stock by 200rpm...

...while the LCE 4-1 long tube header lowers the torque peak under stock by 650 rpm.






p.s. just as a side note...

Bone Stock 2.7
Stock intake
Stock header
Stock exhaust

119hp / 132ftlb

My 2.7
tooter 2.7 spacer
LCE header
Stock exhaust

137hp / 160ftlb

Greg

 

Are you selling the spacers yet?

 

They're for the 2TR and still not done yet because the engineer is working on other bigger projects on a deadline so my small production runs have to wait.

Intake manifold spacers that fit your 1996 3RZ engine are already available from Paradiseracing.com



Greg

 

Thanks!

 

While they're thinner, they're machined out of aluminum and can support the weight of your aluminum intake manifold which hangs unsupported off the side of your engine.

I'm familiar with the 8 port intake manifold...


...as I had a 1996 2.4 for 17 years. The runners are already super long and give the engine lots of low end pull. The spacer should give it a little more.

For even more low end pull, I highly recommend an LCE long tube header. I ran one on my 1996 for a decade and it produces more low end torque than any spacer ever could.



Greg

 

A bone stock 2.7 on the dyno makes 140 ftlbs @ 3,150 rpms.

Greg

 

Yes, it's big enough of a difference to feel.

And what makes the torque difference even bigger is that DTs peak at 4,000 rpms, while LCE's peak is only 3,150 rpms.

I also added two other mods and dyno tested them (Tooter intake manifold spacer, and Flowmaster Series 50 muffler), both of which added a bit more torque while lowering the peak even more. The intake manifold spacer lowered the peak by 250 rpms, and the muffler lowered it another 100 rpms.

Right now, on the dyno, my engine makes 162 ftlbs. @ 2,800 rpms.

I've pretty much gone as far on the 2.7 as I can with non-aspirated bolt on mods. But am totally pleased with the low rpm results as they help normal everyday driving, and none of the mods has impaired reliability, or shortened the service life of the engine.


Greg

 

This is solely bro-science, but I would think that if you're producing more power at the same rpm, your engine wouldn't need to work as hard to turn the wheels thus reducing the fuel consumption. But I'm an accountant, not a mechanic.

 

It's a lot more expensive to fabricate a long tube exhaust header than it is to make the stock exhaust manifold. Besides emissions, another major factor in the design of factory stock components (such as intake and exhaust) is sound. Their goal is a clean quiet vehicle that meets government AQMD standards. My truck obviously violates both emissions and sound standards in a wide variety of ways.

In my opinion, yes.

Torque is not acceleration. That's horsepower. Torque is the resistance to the engine slowing down under increased load. Or the ability to hold the same rpm level under increased engine load. Towing is a good example. An engine with increased torque can't accelerate any faster pulling a trailer, but it can pull the increased load easier.

My truck is always loaded down with 600-800 pounds of tools and materials. But there are times when I need to unload everything to carry other things. And I drive it empty, the engine feels as responsive as when it's loaded. That's torque.

That's about right...
The torque peak of a stock 2.7 is 3,800 rpms. But the absolute peak is only part of the story, it's important that the rest of the curve is fattened up, especially at low rpms. When I'm driving my truck, the engine rarely goes over 3,000 rpms. Most of the time I'm puttering around between 1,500-2,500 rpms. Even on the freeway, 2,500 rpms in 5th gear is 75 miles per hour which is plenty fast for a work truck.


Greg

 

You are correct. When the engine produces more torque it is not working as hard to move the vehicle, so for a given set speed you are pushing less on the accelerator, so the throttle body butterfly is not opened up quite as much.

The ECU also senses engine load (which is a function of manifold vacuum), so it does this by sampling the manifold vacuum through a hose. If it senses less engine load at a set speed, the engine spark timing is advanced more and the injectors can meter a little bit less gas. These both increase gas mileage.

I normally drive my truck under the absolute worst gas mileage conditions... no freeway driving at all, and lots of slow crawling in first gear up and down steep roads. But recently I had the opportunity to take it out on the open road totally unloaded for an 800+ mile trip on the Interstate. Keeping my speed at a steady 60-70 mph I logged 30.6 mpg average for the trip. So that is now my benchmark of the very best gas mileage my truck is capable of.

So the answer is yes... more low end torque does mean better gas mileage.

Greg

 

For the same reason as on a manual transmission... for better gas mileage. The slower the engine is turning at a set speed, the more likely you are to get good gas mileage. This is why 4x4's have lower mileage ratings. Their final gearing is lower.

I was looking for final gearing specs and came across this interesting list:


Top 10 Most Fuel-Efficient 2013 Pickup Trucks

1. Toyota Tacoma regular cab 2WD, 2.7L I-4, 5-spd manual, 21/25/23, $2,200
2. Ram 1500 regular cab HFE 2WD, 3.6L V-6, 8-speed auto, 18/25/21, $2,400
3. Toyota Tacoma regular cab 2WD, 2.7L I-4, 4-speed auto, 19/24/21, $2,400
4. Chevrolet Silverado Hybrid crew cab 2WD, 6.0L V-8, electric transmission, 20/23/21, $2,400
5. GMC Sierra Hybrid crew cab 2WD, 6.0L V-8, electric transmission, 20/23/21, $2,400
6. Chevy Silverado Hybrid crew cab 4WD, 6.0L V-8, electric transmission, 20/23/21, $2,400
7. GMC Sierra Hybrid crew cab 4WD, 6.0L V-8, electric transmission, 20/23/21, $2,400
8. Ram 1500 regular cab 2WD, 3.6L V-6, 8-speed auto, 17/25/20, $2,550
9. Ford F-150 regular cab 2WD FFV, 3.7L V-6, 6-speed auto, 17/23/19, $2,700
10. Toyota Tacoma regular cab 4WD, 2.7L I-4, manual (5) or auto (4), 18/21/19, $2,700

The thrifty base model Tacoma 4 banger with a stick beats them all.


Greg

 

It seems to me that others should have been included in that list, like Nissan Frontier pickup trucks. But the government EPA mileage ratings are accurate.

Here's the 2012 Nissans. They have no standard cabs:

Fuel Economy of 2012 Nissan Frontier EPA MPGMODELCityCombHwy2012 Nissan Frontier 2WD 4 cyl, 2.5 L, Automatic 5-spd, Regular Gasoline 17 City
19
Combined
22Highway
2012 Nissan Frontier 2WD 4 cyl, 2.5 L, Manual 5-spd, Regular Gasoline 19 City
21
Combined
23Highway
2012 Nissan Frontier 2WD 6 cyl, 4.0 L, Automatic 5-spd, Regular Gasoline 15 City
17
Combined
20Highway
2012 Nissan Frontier 2WD 6 cyl, 4.0 L, Manual 6-spd, Regular Gasoline 16 City
17
Combined
20Highway
2012 Nissan Frontier 4WD 6 cyl, 4.0 L, Automatic 5-spd, Regular Gasoline
View MPG Estimates Shared By Vehicle Owners
14 City
16
Combined
19Highway
2012 Nissan Frontier 4WD 6 cyl, 4.0 L, Manual 6-spd, Regular Gasoline

15 City
17
Combined
20Highway

One fascinating bit information is 8 speed automatic transmissions. I had no idea anything that complex even existed... and can you imagine what the repairs would cost?


Greg

 

I can guarantee you that gas mileage on the dyno is as bad as it can get!

And I know what you mean...
Partial throttle efficiency can only be extrapolated from wide open throttle performance on the dyno. The real test is actual gas mileage, and that needs to be logged over time to get an accurate profile of actual engine efficiency. Because driving conditions are always constantly changing, you need a very large sample to even them all out.

Greg