Corolla AE86 HI-Comp


Corolla AE86 HI-Comp

Powering the AE86 is the venerable and potent 4AGE.  In its original form, the engine came with a TVIS system.  This vacuum actuated intake system bridged the gap between high out-put and good throttle response.  Ingeniously, Toyota speeded up air flow to the cylinders by making an 8 port intake runner-  4 of which can be shut-off at low throttle position.  The purpose of this is to give good throttle response at low end without sacrificing top end potential.

With the resurgent interest in these cars- high mileage units are being updated to the later model 4 port Hi-Compression engines.  The later model 4AGEs also come with upgraded crankshafts and rods…and most important higher compression.  This newer engine had enough compression to get by without the TVIS- but use smaller ports instead.

Here lies the dilemma….the TVIS head is considered by many misguided people as a restriction to performance.  IT IS NOT.  The TVIS serves a very important purpose and should be retained.  Combining the advantages of the Hi-Comp late model block with the TVIS head is the ultimate low-cost, high value engine set-up for the AE86.  Stays smog legal too!!  Since the Hi-Comp engines were all FWD applications- fitting into a RWD application is as simple as reusing all the water-pump and hose connectors from the original engine.  All original engine harness and accessories transfer over.  The only electrical modification is splicing the new injector leads to the old harness.

Using the TVIS head is highly recommended, but low budget conversions can use the small port head- if the intake is reoriented to the front.  This is a complicated cut and weld affair.  The original and new (engine) manifold are cut-up and pieced together.  It has to be done right or there will be a dent on the hood the first time you shut it and/or wrong vacuum connections.

(On this particular car the small port head is used with the modified manifold, because the original TVIS head is being fully prepared with big valves, porting, and cams.)

The late small port 4AGE runs very well in the AE86, even with just the modified intake manifold.  The latter retro-fittment with the upgraded TVIS head will further enhance low-end response and high RPM performance.

Many different engine upgrades is the reason why the AE86s remain so popular.  There are many ways to set-up an engine: you can do it a step at a time- as budget allows or just go one stop all-out.  Like the early Celicas and Corollas….this model is a keeper.

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