The LA-Based Four Cylinder Racing Engine

Written in 2002,
revised 2010 and 2017

The A-4 is a racing engine based on the LA 5.2/5.9 V8, available for years from Mopar Performance. There are three major blocks:

  • LA based A4 four cylinder engineP5007466 Midget race block (includes special cooling passages and such; still available from Mopar)
  • P5007467 drag race block (V8 flywheel housing for RWD transmissions) for P5 Hemi head; now discontinued
  • P5007636 wedge-head race block (fits W8/W9 heads and V8 flywheel housing for RWD transmissions); now discontinued

These A-4 aluminum blocks use many Chrysler small block components, with corrected valvetrain geometry (a problem with the LA since it was designed) and a shorter deck height. They were dyno tested and factory sealed for consistent output.

A4 LA based four cylinder racing engineThe midget block was listed at $6,121 (we found it for $5,600) in 2010, with cast iron sleeves, billet steel or billet aluminum main caps, a main cap stud kit, and mounting hardware. It had an unfinished 4.130 in. bore with 8.40 in. or 9.00 in. deck heights; it accepted W9 raised-port aluminum cylinder heads for sprint or Midget racing.

The drag race block listed $5,217 in 2010; it now shows up as having been discontinued. The wedge-head race blocks, listed as being designed for USAC Midget and drag racing, ran $6,644, list, in 2010, and now shows as being discontinued. Both came with steel billet caps, ductile iron sleeves, and a hardware kit.

Dressed midget motor, with cam-driven, dry-sump oil pump and distributorless ignition.

The block top deck is extra thick to allow for O-ringing and forced induction. One racer said, “People using this engine are walking away with all the marbles over the GM ‘Iron Duke’ based engines. Coupled with a Hewland EGT series transaxle, this engine in a lightened Neon (prepped like Gary Donovan’s 10 second Reliant), should be able to dip into the mid to low 9 second ET range in the quarter mile due to lighter potential weight and higher rpm capability.”

Unmachined: rear wheel drive flange for using an A727, A833, etc
 
 P5007961 Full Engine (W9 heads)
Rated power350 hp@ 7200; 265 lb-ft @ 6,000
Redline8,500 recommended; 9,000 max
Displacement162 cid (38 cc combustion chambers)
Compression15:1 (methanol)
Crank and camScat crank, roller cam with 60 mm bearings

The racer continued, “A pair of turbos, sequentially fed through proper charge air cooling, should push the motor to over 600 hp and have far more durability that a 2.2/2.5 or 2.0/2.4 engine, and a higher rpm range.

“The Hewland transaxle mentioned earlier is $16,000 - the price of being the best. A race car of this type costs anywhere from $35,000 to $85,000 to be competitive. NASCAR cars cost from $80,000 to $160,000 each, if not more.”

blockWhen this article was written, the cost for the block (semi machined) was about $1,000 and the Hemi head was about $800 bare and semi-machined. These pieces were released in the 2002 Mopar Performance catalog. The cool looking magnesium valve covers were on page 116.

As far a this engine ever being a “production car piece”... it was intended strictly for racing, and does not meet EPA standards for street engines.

We make no guarantees regarding validity or accuracy of information, predictions, or advice — see the terms of use and privacy policy. Copyright © 1994-2000, David Zatz; copyright © 2001-2017, Allpar LLC (except as noted, and press/publicity materials); all rights reserved. Dodge, Jeep, Chrysler, Ram, and Mopar are trademarks of Fiat Chrysler Automobiles.


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