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Tomei-Powered Poncams

Drop-in Camshafts: Impressive Horsepower Gains

Scott Tsuneishi
Aug 12, 2012
Impp 1207 01 o+tomei powered poncams+camshaft Photo 1/28   |   IMPP-120700-TOMEI
Impp 1207 03 o+tomei powered poncams+camshaft Photo 2/28   |   IMPP-120700-TOMEI

Tomei Powered's newest Poncam camshafts for the 4A-G (AE111 20-valve VVT) engine are regarded as one of the most economical, reliable, easy-to-install camshafts on the market today. What is a Poncam, you ask? The Poncam name is used by Tomei to describe camshafts, designed as a true "drop-in" application and engineered for use on the stock cylinder head, valvesprings, and ECU without compromising performance gains and improved response over the OEM camshaft for both street and track use.

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There are a lot of things to look at when buying a cam, including duration (how long the valve stays open), lift (how far the valve opens), and overlap (how long the intake and exhaust valves are open at the same time). We measured the OEM 20V factory cam with a 250mm duration intake/exhaust with 8.2mm lift (intake) and 7.6mm lift (exhaust). Data gathered from Tomei R&D on the 4A-G 20V factory camshafts revealed that at 6,000 rpm and higher, the stock cams showed severe intake air restrictions and a dramatic drop in power. Tomei claims their Poncams are good for about 15 hp with no other modifications needed. We plan on putting these cams to the test and prove once and for all if they deliver the power they claim.

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The test mule for this project is an '85 Toyota Levin with 40,000 miles on a swapped 4A-G (AE111 20-valve VVT) engine from Japan. The transplanted engine is a fifth-generation 4A-GE model produced in 1996 and is known by Corolla aficionados as the "black top" due to the color of the valve cover. In factory form, this Cosworth-inspired 4A-GE, for which Yamaha designed the 20V cylinder head, is equipped with 45mm individual throttle bodies, 11.1:1 compression ratio, and delivers 165 hp and 119 lb-ft of torque. While the engine seems to run well we decided to perform routine maintenance prior to testing to extract maximum horsepower.

4A-G (AE111 20-Valve VVT) Engine Specs:

  • AE111 Individual Throttle Bodies
  • T3 Velocity Stacks
  • T3 ITB Splash Guard
  • Jubiride Filter Screens
  • SP-Tec Distributor Relocation Kit
  • Ultra Silicone Plug Wires
  • Techno Pro Spirits 4-1 Exhaust Manifold
  • HKS Hi-Power Exhaust
  • Samco Radiator Hoses
  • Koyo Racing Radiator
  • SamQ 20V Water Line Kit
  • Earl's Stainless Steel Lines
  • Earl's Oil Cooler
  • Greddy Oil Filter Relocation

1. The Tomei Poncam has been designed and tested to be a good street grind camshaft with 264/256mm intake/exhaust duration and 9mm lift. Engineered as a true drop-in camshaft, you won't notice a big change in idle and your car should run pretty close to the way it did before the cams were installed, but with additional midrange and top end performance gains while maintaining usage of your OEM ECU. Aftermarket camshafts sporting aggressive durations are really made for use in the 5,500-plus rpm range, not typically what you would want out of a street car. Opening the intake valve during high acceleration from the camshaft requires sending as much mixture to the cylinder in the shortest time possible. However, if the cam profile is too aggressive/high, it can damage the valves, valve seats, and valvesprings. The Poncam's asymmetrical profile design given to the camshafts will allow the intake and exhaust valves to fulfill the target requirement with the wider duration and high lift without damaging the valvetrain. The factory ECU also has its limits with aggressive cams and isn't very good with any camshafts more aggressive in duration/lift past these Poncams not to mention shelling out additional cash for a stand-alone ECU/re-chipped unit.

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2. Cam installation isn't very difficult on the 4AG-E and took three hours from start to finish, which also included stopping periodically to snap photos. Luckily, we had Shingo Yugami of Bluemoon Performance, a 4A-G specialist with 25 years of automotive repair and tuning experience, help with the install. Shingo was known as a master Toyota technician in Japan but has experience in all imports, ranging from old and new, domestics, classics, and euro. He currently opened his own shop while commissioned to build race engines and chassis construction for drift and time-attack vehicles in the United States. Check out Shingo-san's pimp-ass JDM hat!

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3. Installing the Tomei Poncams is a straightforward process, since the 20V engine uses a direct cam lobe-on-bucket design. Each lobe sits on top of the valve assembly it actuates and is spaced by a shim under-bucket. There are no timing chains, VTEC solenoids, rocker arms, or secondary lobes. Just a matter of pulling the valve covers, loosening the timing belt, removing the cam gears and caps, and yanking the bumpsticks.

Impp 1207 11 o+tomei powered poncams+SP TEc 20 valve 4AG distributor relocation kit Photo 11/28   |   IMPP-120700-TOMEI

4. The SP-TEC 20-Valve 4AG Distributor Relocation kit is a must have for AE86 owners when attempting to help ease the 20V swap in a 20-valve 4AG motor from the AE101 and AE111. The custom kit allows plug-and-play without having to bang the firewall to clearance the cap and rotor or having to dish out additional funds for an aftermarket ECU.

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5. Make sure your distributor rotor is pointed at the number one spark plug wire when your car is set to top dead center (TDC), marking it with a Sharpie. With the timing marks lined up, make sure that cylinder one is at TDC on the compression stroke. Then, as you lower the distributor back in, make sure that the rotor is pointing to the number one plug wire post on the distributor cap. Be sure to mark the distributor since you can't install it with the cap on.

Impp 1207 13 o+tomei powered poncams+distributor rotor Photo 13/28   |   IMPP-120700-TOMEI

6. The shim adjustment was almost made unnecessary according to the size of the Poncams' cam base circle. Because the 4AG has a cam lobe on either side of a cam-bearing journal, it makes it critical that adequate clearance is given among the lifter (bucket) and shim and the bearing journal surface.

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7. As a precautionary measure, we decided to measure each shim using a micrometer to achieve proper shim thickness. This procedure is often time consuming and a costly process, but is an important procedure that cannot go ignored.

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8-9. Be sure to inspect both buckets and cam journal bearing for any excessive wear.

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Impp 1207 19 o+tomei powered poncams+cam journal Photo 18/28   |   IMPP-120700-TOMEI

10-11. Each Tomei camshaft is coated with manganese phosphate in order to protect from damage even when the camshaft is not lubricated. We slathered down both the camshafts and journals using Torco assembly lube prior to reassembly.

Impp 1207 18 o+tomei powered poncams+torco assembly lube Photo 19/28   |   IMPP-120700-TOMEI
Impp 1207 21 o+tomei powered poncams+feeler gauge Photo 20/28   |   IMPP-120700-TOMEI

12-13. The Poncams have also been designed to eliminate the need for adjustable cam sprockets or unnecessary "dialing in" of the cams as the knock pin has been preset for optimal timing. We torque the cams' caps before using a feeler gauge to check for proper clearances on both cams.

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14. Tomei Poncams also includes a degree card to properly dial in the camshafts.

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15. Clean fuel injectors are a must for peak engine performance, fuel economy, and emissions. Dirty injectors lack the necessary means to deliver proper amounts of fuel and cannot maintain the correct spray pattern that is essential for efficient combustion. Injectors are exposed to extreme heat, which evaporates fuel from the injector surface at engine shutoff, leaving gasoline distillates to build up and bake on the nozzle, impeding the flow of fuel. Companies like RC Engineering specialize in inspecting, cleaning, and flowing injectors of all sizes for both street and race applications.

Impp 1207 23 o+tomei powered poncams+fuel injector test Photo 23/28   |   IMPP-120700-TOMEI

16. RC Engineering cleaned our OEM injectors using three different steps: an ultrasonic cleansing bath, in which the injectors are submerged and actuated in a concentrated solvent and subjected to ultrasonic vibration, followed by a high-pressure reverse-flow solvent stream, and ending with a mediablasting to the injectors' bodies and the replacement of all seals, O-rings, and nozzle covers.

Impp 1207 24 o+tomei powered poncams+injector cleaning Photo 24/28   |   IMPP-120700-TOMEI

17. The '96; 4A-G (AE111 20-valve VVT) Nippon Denso 296cc/min saturated injector

Impp 1207 25 o+tomei powered poncams+nippon denso saturated injector Photo 25/28   |   IMPP-120700-TOMEI

Before Cleaning
Injector #cc/minPattern
After Cleaning
Injector #cc/minPattern

18. Once installed, we used a timing gun to check the timing before driving around the block to check for any problems.

Impp 1207 26 o+tomei powered poncams+timing gun Photo 26/28   |   IMPP-120700-TOMEI

19-20. With the car running good, it was time to put it on the dyno for its baseline run. On its first pull the car made 122.2 whp and 100.2 lb-ft of torque at the wheels. After the baseline run we checked the timing, and it was set to 5 degrees BTDC. We changed it to the factory setting of 10 degrees and dyno'd the car again. With the timing in the correct spot the power climbed to 126.1 whp and 103.2 lb-ft of torque. We started with back-to-back dyno runs between the stock and Tomei cams, which gained a peak of 14 hp and 7 lb-ft of torque that increased power gains throughout the powerband. Over 15 lb-ft of top end torque was gained above 6,000 rpm to redline (where the stock cam fell off). If we weren't rev-limited, the Tomei cams would have made more power as the power curve was still climbing at rev cut. With ECU tuning, the engine should be even more responsive in the mid- and high-range power, but as a simple drop-in cam with no other modifications needed, these Tomei bumpsticks were impressive indeed!

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Impp 1207 27 o+tomei powered poncams+dynograph Photo 28/28   |   IMPP-120700-TOMEI


Tomei Powered USA, Inc.
Lake Forest, CA 92630
Cusco USA
Huntington Beach, CA 92647
RC Engineering
Torrance, CA 90501
SR Motorcars
Bluemoon Performance
Costa Mesa, CA 92626
By Scott Tsuneishi
247 Articles



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