How To: Swap a 20v by System

Changes that need to be made to accommodate the 20v by system

1. Exhaust

-Silvertop

The complete 16v exhaust system can be used with the 20v silvertop. The only needed modification will be to the outermost flanges of the stock 16v header (pictures are of an ae86 header, but the bolt patern is the same)

Incidently, the egr hole on the 16v header can be blocked with a transmission fill or drain bolt.

The 20v header can also be used, but will require either a custom bpipe, or modifications to an existing 20v bpipe. The 20v silvertop header also has clearance issues with any exhaust side mounted starter. Clearance between the ST header and starter will only be a few millimeters.

The diameter of the 20v header pipes is identical to those on the 16v. The 20v header may have a slight advantage due to the use of theta plates, but dimensionally, the headers are the same or similar.

-Blacktop

The 16v header can also be used with the blacktop, but will result in power loss due to the Blacktop’s larger exhaust ports. A typical 16v header/manifold will be a bit constricting. 16v manifolds have been used with blacktops, so it is possible. Larger diameter 16v headers may be available.

For best results, use the blacktop header (or exhaust header that has the same exhaust port dimensions) when possible.

The exhaust mounted starter will not clear the larger diameter blacktop header. This will be an issue with any 1985-1987.5 20v conversions where the original c50 transmission is to be used since these transmissions lack the intake side mounting position. You really have 3 options in this situation.

a. Use the 16v setup, and take the performance hit
b. Use a later c52 transmission (or bellhousing) that does have the intake starter mounting position
c. Modify the 20v header to clear the starter.

Once again, a custom bpipe will have to be made, or an existing bpipe modified

Keep in mind that 87+ mr2’s used a larger diameter bpipe, cat, and muffler, so this is your best choice for the 20v. The 4agze equipped mr2’s used the same exhaust setup as the NA cars did.

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This documentation in no way replaces the Toyota MR2 Repair Manuals. The purpose of this content is only to provide supplementary information to fellow MR2 enthusiasts. Midship Runabout and its contributing authors will not be held responsible for any injury or damages that may occur as the result of practicing any of the methods or procedures described within this website. Article and photo submissions are property of the contributing author.


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9 Responses

  1. Jason McDaniel says:

    Can I get contact info to buy a harness?

  2. Jimmy Lam says:

    Got a 1993 Corolla dx station wagen stick shift, would like to swap from 7afe (stock engine) to 4age 20v BT, need some tech advise and would buy a plug and play harness from you, pls contact me via the above email, much appreciate your post and have a great day.

  3. Troy says:

    Hey, I’m planning to do this swap over the summer, how do I get one of these ‘plug and play’ harnesses?

  4. Daniel says:

    I am also interested in a harness, could you please get in contact with me if its still an option. I have a mk1 mr2 with the swap already done, but it was done poorly and the harness is hacked….

  5. yerv says:

    hello there,
    I would also like to purchase one of these harnesses. Please get back to me as this wiring stuff was the only thing holding me back fromfrom finally tackling the swap

  6. Addison says:

    Hi,

    Thank you so much for your post it is very helpful! Can I buy a plug and play harness from you? I am planning on doing a silvertop swap with my aw11 soon. Thank you!

  7. daniel says:

    yet another request for a harness……is it still something you can do? can you source the original harnesses as well? thank you for your time.

  8. Michael says:

    good day,. i have a ee100 with 2E engine swapped with 4age BT,. what do i need to have my exhause pipe fixed, pls comment on sensors needed to be added and/or installed pipe sizes, for proper functionality of the engine

  9. mr220v says:

    Looks like this old writeup of mine travels far. Originally did it on mr2.com 6 years ago maybe.

    PNP harnesses can be ordered at http://www.wiregapinc.com

    I swap the 20v among other things.