The high/low hybrid is a great solution for those that are in need of a replacement engine due to high mileage, engine failure, etc. The high / low hybrid won't be the greatest performance gain but it will often get you back on the road with the least hurt on your wallet. So if you are looking for a great replacement engine and not so much of a performance upgrade, read on!
The stock 16v low compression (blue top) engines are somewhat hard to come by these days with low miles. The solution is to make the jump to the newer and much more readily available high compression engine. The high compression (red top) had a much longer production run-time and came in many different cars so its generally very easy to get low mile, warranted high compression engines. The swap is not only the cheapest but also one of the easiest. There are a few points of interest along the way and this article will cover them all.
The basic explanation of the high comp/low comp hybrid is; Removal of the small port head from the high compression engine and replacement the head with the OEM motors large port head. The low compression head and high compression blocks bolt directly up to either head, the primary reason for the use of the the low comp. head is to allow the use of all of the OEM manifolds and accessories. If the high comp. head is retained, you would be forced to modify the intake manifold, fuel system, EGR and some electronics. With the hybrid, you are getting the best of both worlds. Lets get specific on the progression you will need to make;
Upon removal of your OEM engine, you will need to be careful to ensure that nothing is lost or discarded. You will need almost everything on the stock engine to adapt the high compression engine to a RWD layout. After sourcing the high compression engine, strip it down to just the engine block. Once the new engine is entirely stripped and cleaned, the process of installing all RWD parts begins, you will need to remove and install the following parts from the OEM engine and onto the new high compression engine. It is strongly recommended to take pictures of the complete OEM engine after removal to reference later during the rebuild to ensure correct transfer of the components onto the new engine. NOTE: All of the following are all direct bolt on parts no modification will be required. Although no modification will be required two minor issues will be encountered and both issues are addressed in the Miscellaneous Notes below.
Engine components needed for swap:
- Oil pan and baffle
Oil cooler sandwich plate (Note the alignment pin)
Intake manifold + TVIS
Engine cylinder head
All engine mounts, braces and brackets.
All accessory brackets (AC/PS/ALT)
Entire cooling system (Plumbing + Pump)
Once the high compression engine has all the parts and acessorys from the OEM engine it's ready for install. The installation of the engine itself will be exactly the same as a stock engine replacement.
- The high comp. head and block have an oil return jacket that dumps from the head to the block when using the low compression head, the return line is not present so the line off the block will need to be capped. Rubber plugs or simply crushing the tube will serve as great options for resolving this issue.
- The High Comp engine has a knock sensor located on the intake side of the block... when using all stock electronics, you will not need this knock sensor and it will interfere with the water line that runs the length of the block. Simply remove from the block to make room for the water line that runs down the length of the block.
- It is strongly recommended that all gaskets/belts be replaced and cylinder head resurfaced preior to install.