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Rev Limit Setting From Drift Tengoku

	Some drifters of this era can be seen bouncing their rev limiter during their runs. Instead of shifting to another gear, they keep on the gas. They don't shift because by keeping on the throttle, the machine can be lunged forward to the targeted area, and the sounds protruding from the machine can be a benefit in terms of judging. But this technique is very bad for the engine. By cutting off the ignition at this point the engine can be ran rather safely.

	This Ignition Cut Off is a Must for the Heavy Footed!
	For drift machines, keeping on the throttle as long as possible to keep the power band, as well as that extra second needed for that corner transition can be achieved by staying at the top end. Although this is a effective technique, it can take its toll on the camshafts and the valve assembly. Some worst case scenarios include the pistons hitting the valves, or the rocker arm dislodging off the cam lobe. To avoid these troubles, Mr. Inose from the shop Friends recommends that while drifting, controlling the revs are absolutely critical. The stock ECU regulates over revving by cutting off fuel at the set rpm range. This is also called fuel cut. This can lead to engine knock, and may inflict serious damage to the engine if repeated. Inose claims that "fuel cut off and hitting th rev limiter sounds awful and may lead to a deduction of points during a competition." The solution to this potentially dangerous problem is to cut off the ignition instead. By doing so, the engine will never knock, and produce a more smooth, yet intense noise. However, to perform a ignition cut, the ECU needs to be reprogrammed. Inose recommends the Tectom IIC-640. There are other stand alone ECU systems that work such as the Fcon Vpro which provides more precise settings in smaller increments. Conversely, with this unit, the engine keeps spinning 200 rpm above the set cutoff point from sheer force. The IIC-640 prevents this occurrence. By cutting the ignition at the desired rev range combined with larger injectors, the revs can be safely bounced more than three seconds. One negative aspect of the ignition cutoff is that the unburned gas ignites in the exhaust manifold, causing cracks in the exhaust components because of the heat. This is the reason why some prefer to use fuel cutoff.

	Summary
	•Fuel Cutoff can damage the engine! •The sound produced after the ignition cutoff is more intense! •The Techtom IIC-640 can be applied easily!

		Cutting Rev Limits for over 6 years, Touru Inose
		He has been tuning ECUs long before he started working at the tuning shop Friends. Using a datalogger priced at 10k, Inose tunes vehicles with large turbos and nitrous setups. The S15 D1 vehicle he competes in is equipped with a T67 turbine + NOS pushing over 600 horses.

	Comparison! Examining the two rev limit methods on a datalogger!

	Ignition Cutoff (Techtom IIC-640) Silvia S15 T67 Turbine				Fuel Cutoff (Stock ECU) Silvia PS13 TD06-25G Turbine
	· The Techtom IIC-640 was programmed at 8200 rpms to cut off the ignition. Unlike the fuel cutoff, the ignition cutoff did not produce any knocking (yellow line) of the engine. Since the cutoff was wet at 8200 rpms, the actual cutoff resulted at 8000 rpms, 200 rpms below the set target. The datalogger is used to acquire valuable data such as this graph.				· The stock ECU was set to cutoff fuel at 7800 rpms. Since the fuel cutoff (green line) was set to cutoff at 7800 rpms, the engine spun all the way to up 8300, and as less as 7000 rpms. This can inflict damage to an SR engine's rocker arms as well as produce engine knock.

	Recommended Ignition Cutoff Just install the Techtom IIC-640				Recommended Fuel Cutoff Reduce the damage by adjusting the ignition timing!
	· Techtom IIC-640 cut the ignition without requiring to modify the stock ECU. But the ignition cutoff should be set to cutoff at higher RPM than the fuel cutoff due to get the wide band of effective rpm.				· The S15 with GT-SS turbine has fuel cutoff at 8000 rpm. To reduce the damage from the knocking of a engine while the fuel is cutting off, the ignition timing was changed from 18 degrees to 10 degrees at 7500-8000 rpm.

		Fuel and Ignition Cutoff! HKS Fcon Vpro			Precise Ignition Cutoff! MOTEC M400
		Although a ignition cutoff is performed, the rpms can over ride the set limit. This computer takes that into account, and sets the ignition cutoff 500 rpms above the set range. Since it enables precise setting in small increments, the results are spectacular.			Although this unit costs 248,000 yen (~$2,300.00), it provides 2 stages of ignition cut. One setting is the soft cut, which gradually cuts the ignition followed by the hard cut, which fully shuts it off. This prevents damages inflicted by a hard ignition cutoff. This unit also can be used for fuel cut as well.

		Available at Apex Dealers! APEX POWER FC			New Ignition Cutoff TRUST e Manage Ultimate
		The Apex unit has a built in fuel cut feature. Plus, the Power FC units bought at an authorized Apex dealer (Japan only), they ignition cutoff can be utilized by plugging it into a computer.			The eManage had evolved to a Ultimate model. Although this is a piggyback ECU, it provides both ignition and fuel cu settings with the use of twin map. The former eManage did not provide the fuel cutoff option. The unit is priced at 62000yen ($600.00), a very competitive item next to the IIC-640.

		Part 1 Be Careful of Cracked Headers!			Part 2 Rocker Arm Failure
		Ignition cut results in unburned fuel combusting in the exhaust manifold. The manifold starts to glow red, and become very hot. Be aware of this, and keep an eye out for any cracks. By Mr. Eguchi (Friends)			Though it happens more often after a fuel cutoff modification, the rocker arms may become dislodged and out of spec after a ignition cutoff as well. Please keep an eye out for valve lash and adjust them periodically.

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