The Merkur Encyclopedia

Component: Charge Cooler (Intercooler)

OE: None on Merkur, standard on the SVO and TC. The TC one has slightly better flow than the SVO part, but both are inadequate for high flow engines. Also, the placement of both have limited air cross flow so the operational efficiency is not high.

Intercooler Flow @ 28" H2O
SVO 320
TC 360

The compressor housing on the non-OE intercooled have a different bolt pattern to the input elbow than the OE intercooled 2.3s. The bolt pattern is rotated about 30 deg clockwise. To rotate the compressor housing to accommodate most intercooler installations there are 3 options: get an OE intercooled compressor housing, cut and reweld the input elbow or buy an adapter.

Periodically cleaning the inside of the cooler core is very important. Any oil or dirt will dramatically reduce the efficiency of the charge cooler.

Several are available from the aftermarket. Most are placed such that they get good cross flow. Not all are sized large enough for high flow engines. The sizing of the core and tubing is critical to prevent flow restriction. Routing and insulation on the tubes is important to prevent radiation from the exhaust manifold heating the cooled charge air !

Home made intercoolers can work just as good as purchased kits. The same design issues of: high flow, isolation from heating, good cross flow air are still important. Adding insulation such as bubble pack wrapped with aluminum foil can dramatically reduce heating of the tubes. Simply touching the tubes after a hard run will indicate where insulation should be located. See exhaust manifold section for adding heat shields.

Water-to-air charge coolers are an alternative to air-to-air intercoolers. The advantage to water is that at stopped or low speeds they are still effective. The disadvantage is added complexity of adding a: tank, pump, plumbing, heat exchanger, in addition to the core itself.

Spraying water on the charge cooler core can evaporation cool the core at low speed or high boost. Using a pressure switch in the charge air to turn on the sprayer can be quite effective.

The compressor adapter is available from:
Greg Paul
125 Woodstream Ct
Fayetteville, GA 30214



By cooling the charge air (intercooler) more air molecules can be pumped into the engine. This is due to the increase in air density, which is a function of temperature. See the "turbo and intercooler efficiency" chart for an analysis showning the flow increase through the engine by increasing the charge air density.

Note that inceasing the flow through the engine also increases the flow through the compressor. This increase usually moves the operating point of the compressor to a less efficient region (see turbo compressor map), which reduces the net incresase in density.


Practical Obversations by Nick

Air to water coolers are best used for drag racing only. The temp drops are never as good as a well built air to air system. The main problem is the water heat exchanger cannot cool the water as close to outside air temps. In a drag race set up you can use ice water to drop the temps a great deal more then just with water alone. You would need a very large heat exchanger along with a very large holding tank. (the heat rejected by either system is the same, so similar size surface is required. ed) The large exchanger in front of the radiator will cut down on air the cool the coolant in the radiator. All factory/stock air to water coolers are used because of packaging reasons over performance reasons. Almost all air to water system are replaced with air to air system when more power is needed or for competition. I have never seen an air to air replaced with an air to water system, outside of drag racing or maybe a car like Rick's.