Getting an ae85 today, and I'm making plans for it. I won't have money for a 4AGe for a while, so I am wondering if aftermarket internals are interchangeable between the two motors. I want to save money when I make the swap, so I'm mainly interested in if 4ag high compression aftermarket pistons will work in an AC until I get an AG

Hey! First off, welcome to the forum!

Second, the US never got AE85s, so you are thinking about an SR5. Parts between the 4AC and the 4AG shouldn't be interchangeable, as far as I remember.
Personally, I don't believe that sinking money into the 4AC is worth it. Instead, you can work on suspension and getting to know the car.

Also, you can use the search button on here or on the archives to see if someone has said anything about.

NoobishAe85 wrote:Getting an AE85 today, and I'm making plans for it. I won't have money for a 4AG for a while, so I am wondering if aftermarket internals are interchangeable between the two motors. I want to save money when I make the swap, so I'm mainly interested in if 4AG high compression aftermarket pistons will work in an 4AC until I get an 4AG

If you haven't already, you should register at 4AC Powered and ask this question there too: http://4ac-powered.forumotion.com/

I did some research into if 4AG pistons would work in a 4AC a while back.

Seems like the bigport / bluetop 4AG pistons will work in a 4AC, although you have to double-check your timing on both the crankshaft and camshaft (don't want the valves making contact with the pistons). I believe the 4AC will then be an "interference" engine, which doesn't mean there's any valve to piston contact, but rather if your timing is off or your timing belt breaks there can be valve to piston contact.

Turning a non-interference 4AC into an interference engine shouldn't put you off; most modern engines are interference engines.

There's also the bigport / redtop 4AG pistons, which have a 20mm wrist pin (the bigport / bluetop ones have a 18mm one). No info on whether or not they'd work with a 4AC head, but I'm betting they would. Again, double-check your timing and clearances.

Finally, there's the smallport / redtop 4AG, which has higher compression pistons than either of the 4AG engines I mentioned before. I don't think these pistons will work with a 4AC head, but then again, I haven't tried.

As for what's different between the 4AC and 4AG, obviously the head is different, the 4AG has higher compression pistons, and (among other things) the 4AG has an 8 bolt flywheel, whereas the 4AC only has a 6 bolt.

What are your plans for the 4AC? Some 4AG mods won't work on a 4AC.

Personally, if your plan is to swap the 4AC, I'd focus on mods other than the engine first. Suspension, the transmission (if your car is a manual, you should definitely get this: https://technotoytuning.com/toyota/ae86/shifter-rebuild-kit-ae86-corolla assuming your car doesn't have one already), and steering are all good places to mod before you touch the engine, aside from general maintenance on it.

Good luck!

yellowsnow4free wrote:

NoobishAe85 wrote:Getting an AE85 today, and I'm making plans for it. I won't have money for a 4AG for a while, so I am wondering if aftermarket internals are interchangeable between the two motors. I want to save money when I make the swap, so I'm mainly interested in if 4AG high compression aftermarket pistons will work in an 4AC until I get an 4AG

If you haven't already, you should register at 4AC Powered and ask this question there too: http://4ac-powered.forumotion.com/

I did some research into if 4AG pistons would work in a 4AC a while back.

Seems like the bigport / bluetop 4AG pistons will work in a 4AC, although you have to double-check your timing on both the crankshaft and camshaft (don't want the valves making contact with the pistons). I believe the 4AC will then be an "interference" engine, which doesn't mean there's any valve to piston contact, but rather if your timing is off or your timing belt breaks there can be valve to piston contact.

Turning a non-interference 4AC into an interference engine shouldn't put you off; most modern engines are interference engines.

There's also the bigport / redtop 4AG pistons, which have a 20mm wrist pin (the bigport / bluetop ones have a 18mm one). No info on whether or not they'd work with a 4AC head, but I'm betting they would. Again, double-check your timing and clearances.

Finally, there's the smallport / redtop 4AG, which has higher compression pistons than either of the 4AG engines I mentioned before. I don't think these pistons will work with a 4AC head, but then again, I haven't tried.

As for what's different between the 4AC and 4AG, obviously the head is different, the 4AG has higher compression pistons, and (among other things) the 4AG has an 8 bolt flywheel, whereas the 4AC only has a 6 bolt.

What are your plans for the 4AC? Some 4AG mods won't work on a 4AC.

Personally, if your plan is to swap the 4AC, I'd focus on mods other than the engine first. Suspension, the transmission (if your car is a manual, you should definitely get this: https://technotoytuning.com/toyota/ae86/shifter-rebuild-kit-ae86-corolla assuming your car doesn't have one already), and steering are all good places to mod before you touch the engine, aside from general maintenance on it.

Good luck!

You posted damn quick

Clouds wrote:You posted damn quick

lol, same to you!

What can I say, I'm a little bored at work on a Friday

You wouldn't want to put pistons into your 4AC, use them for a while and then put them into another motor.

As mentioned put money into the other parts of the car you plan to keep.
Then buy a 4AGe and start building it as you have time and money. Once it's done then you swap it in.

find a cheap 4ag block and throw the 4ac head on.
i built one(largeport block) for about $100.

bored on an air force base and tired of waiting for parts i threw it together so i could at least drive my car!
pretty responsive.



all fun aside, its probably best to keep the engine you have and make sure to get it running properly so you can get to learn the car and modify according to your driving style.
a lot of times people are in a rush for power or takumi lyfe that they end up with under thought engines, hasty suspension upgrades and have a hard time figuring out why they arent doing so well at events.

take your time and learn the car, mod accordingly!!!