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1998 Honda Civic EX - Intake/Exhaust/Headers Install and Dyno

Text, photos, and testing (on Dynojet 248C)

Richard Fong
Mar 13, 2007
0506_ht_01_z+1998_honda_civic_EX+side_view Photo 1/8   |   1998 Honda Civic EX - Intake/Exhaust/Headers Install and Dyno

DYNO 1
Baseline / 106.1 HP / 94.0 lb-ft

Baseline
Nothing too fancy here. A regular, affordable workhorse Civic. Spacious engine bay. Lots of possibilities if you want to go the swap route. But we wanted to see what the single-cam D16 could do with a little help. It's got VTEC, so that's a start.

2018 Honda Civic
$18,940 Base Model (MSRP) 28/40 MPG Fuel Economy
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The Civic we've chosen to work with has about 92K miles on the odometer-plenty broken in, but dying for a little more go.

Air temperature
67 degrees F

DYNO 2
Weapon-R Secret Weapon Intake
109.3 HP / 95.8 lb-ft

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Intake
The Secret Weapon intake is a straightforward install, it's handsomely polished and tastefully designed. The fitment is right on the money and all necessary hardware is included. Weapon-R designed the intake filter frame to also accommodate its optional ram air duct kit, adding versatility and flexibility to the system. We pulled 109.3 hp and 95.8 lb-ft at the wheels and expect more if we'd have gone with the ram air kit. The intake's pipe bracket is a bit hokey. We'd expect Weapon-R to weld the bracket to the piping. Another annoyance: no illustrations accompany the instructions. No big deal if you're experienced, but first-timers will need to feel their way in the dark a bit.

Note: air temp rode 2.5 degrees, which robbed us of a little power. The intake pipe got a little heat soaked, so we waited awhile before making more pulls. We lost some torque in the low-rpm range but made up the difference in the midrange and after VTEC came on. The install is straightforward, but we had to bend the mounting bracket ourselves and find a mounting location. Nice plus: the motor wasn't noticeably louder than with the factory airbox. Bottom line: we gained 3 hp and 2 lb-ft.

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Parts
The Weapon R kit lists for $200 and includes filter, intake pipe, hose, hose clamps, silicone hose, bracket, instructions, decals and license plate frame

Tools
8- and 10mm socket, extension, ratchet, pliers and standard screwdriver

Installation Time
45-60 min

Temperature
Air temperature @ 69.5 degrees F
Temperature difference from previous run: +2.5

2000 to 3500 hp range: -3 to 0 / TQ range: -8 to 0
3500 to 5500 hp range: -1 to 3 / TQ range: -1 to 5
5500 to redline hp range: -1 to 4 / TQ range: 0 to 3
Peak hp 109.3 / TQ 95.8

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DYNO 3
GReddy EVO2 stainless-steel exhaust
112.9 HP / 97.5 lb-ft

Exhaust
This is a really sweet exhaust in both appearance and sound. It's not too loud and features mandrel-bent tubing and a mirror-polished finish. The offset canister hides most of the muffler under the bumper so you only see the exhaust tip. It has great clearance, especially on lowered cars. We made 112.9 hp and 97.5 lb-ft of torque. Fitment and finish are first class, pretty much what you'd expect from GReddy. And it's street legal.

We gained back some low-end torque and gained some mid- and high-end torque and horsepower. The exhaust breathes better than stock without sacrificing too much torque-giving backpressure. Temperature again rose between runs. Remember to use WD-40 on all of your hangers and bolts. The stock exhaust bolts were pretty rusty on this East Coast car.

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Parts
The GReddy EVO2 lists for $629 and includes stainless-steel muffler, B-pipe and S-pipe, gaskets, GReddy badge, warranty card and bolts

Tools
12mm and 14mm combination wrenches, 14mm socket, ratchet and WD-40

Installation Time
45 min

Temperature
Air temperature @ 74.2 degrees F
Temperature difference from previous run: +4.7

2000 to 3500 hp range: 0 to 1 / TQ range: 0 to 2
3500 to 5500 hp range: 0 to 3 / TQ range: 0 to 2
5500 to redline hp range: 2 to 4 / TQ range: 0 to 3
Peak hp 112.9 / TQ 97.5

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DYNO 4
GReddy Stainless-steel headers
118.9 HP / 99.9 lb-ft

Again, outstanding fit and finish from GReddy. The headers added 6 hp and 2.5 lb-ft. Air temp rose another 4.3 degrees. The headers have a CARB exemption number welded right onto the pipe, good foor those times when you'll have to explain your engine bay to the po-po.

Removing the stock header can be tricky, especially since Honda mounted one of two oxygen sensors right into the four-into-two section of the stock header. Wait until it all cools down, then remove the heat shield and the splashguard, unplug the harness, and drop the stock unit out as one piece. You can then easily remove the stock O2 sensor and transplant it into the GReddy unit. Neatly run the O2 extension from the back of the motor to the front and reattach it to the main wiring harness. Don't forget to wipe down the stainless-steel surfaces before running the engine, or you'll find your fingerprints permanently inked into the pipes.

Bottom line: for this power upgrade session, we spent $1,268 and gained nearly 13 hp and 6 lb-ft. Sounds like a little for so much, but this motor certainly displayed the difference on the road. Anything you can do to help the D Series breathe better will reveal itself fairly quickly under throttle.

0506_ht_08_z+1998_honda_civic_EX+greddy_stainless_steel_headers_dyno Photo 8/8   |   1998 Honda Civic EX - Intake/Exhaust/Headers Install and Dyno

Parts
GReddy stainless-steel 4:2:1 headers list for $439 and include oxygen sensor harness extension, bolts, gasket, warranty card and GReddy badge

Tools
Ratchet, 12mm socket, 6-inch extension, 12- and 14mm wrenches, WD-40

Installation Time
45 min

Temperature
Air temperature @ 78.5 degrees Fahrenheit

2000 to 3500 hp range: -3 to 2 / TQ range: 0 to 2
3500 to 5500 hp range: 0 to 4 / TQ range: 1 to 4
5500 to redline hp range: 3 to 6 / TQ range: 2 to 4
Peak hp 118.9 / TQ 99.9

CONCLUSION
 HP LevelHP+TQ Level TQ+
BASELINE106.1 94.0
WEAPON-R SECRET
WEAPON INTAKE109.3 3.295.81.8
GReddy
EVO2 EXHAUST112.9 3.697.51.7
GREDDY
STAINLESS HEADER118.9 6.099.92.4
 
FINAL118.912.899.95.9

Sources

GReddy Performance Products
Irvine, CA 92618
949-588-8300
http://www.greddy.com
Weapon-R Competition Products
http://www.weapon-r.com
By Richard Fong
10 Articles

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