Introduction / 7age 20v BT questions

[v33sonata]

Hey guys,

Let me 1st start off with a little history on my car. I have an 1985 AE86 coupe. Its gone from stock to a 4agze swap to a 7agte swap. After blowing up my 7agte engine a few times. I figured I was done with turbo and went online and picked up a 20v BT. After finally installing it the engine was toast (see vid below) I think rod knock but havnt opened it yet. So I'm once again stuck with a none running engine in my corolla. So the question is what to do next? Here is what I'm thinking I have my old built 7a block with h beam rods and forged pistons ect. sitting in the garage with bad pistons. I was gonna get a set of custom pistons made to mate with the 20v BT head. Some questions I have are, What timming belt do I use for this set up. Keeping the stock ECU for now how much compression ratio can I do on the pistons and what is max bore of the 7a block. I am currently at 82.0mm I am hopeing you guys can help me out. Is it worth even doing this or would I rebuild the 4a block. I know everyone likes the 4a over the 7a casue you can rev it. but my 7a has a new set of hbeam rods and should handle the revs. Thanks in advanced guys!

[Vaughn]

70XIN would probably be the best person to ask, He just had a BT 7age in his 86. He is a Busy man but shoot him a PM

[v33sonata]

Thanks fo rthe input.

[JinxD]

Hey dude my 7age blacktop is built with
Oem 20V pistons
Spool forged connecting rods
And ae111 engine management.
To run the 20V head you need to get a recut crank keyway so you can line up your timing marks.
When building a 16v 7age you can get away with just using adjustable cam gears but as the 20V has the VVT you don't have that option.
Ill find out the part number for the timing belt

[Jip86]

Remember when you are getting pistons to take into account the extra compression from the longer stroke, as in a 20v 82mm 12:1 piston for a 4a will end up being around 12.5-13:1 in a 7a depending on head gasket thickness.

Your compression ratio would really depend on the fuel octane that you plan to run.

7oxin got his keyway cut in nz if i remember correctly because its out by 10 deg or something.

Feel free to post up the list of parts you are thinking of using with specs, there is enough of us now with 7a based builds to have a good depth of knowledge.

I'd go 7a, power wins a pissing contest at the pub, torque wins races.

[Delazy]

A lot of information around already...you shouldn't have any issues finding what you need...a lot of the myths/rumors have been busted since myself and Seamus built up our motors...

Mine yet to actually run...

Ported AE111 head
Kelford 288/10mm cams (modified spark plug tubes to clear)
Supertech valve train (springs, retainers and valves)
Toda cam gears
VVT & CAS deleted

late 7AFE block
Nitrated 7AFE crank
belfab conrod's
custom wiseco pistons (~11.5:1 final cr)
ae111 oil pump + toda strengthened gears
modified timing gear
modified tensioner
toda 16v timing belt

sump spacer
20v windage tray
20v sump pan

Modified intake manifold (intake angle/water meth nozzles)
ae111 itbs
100mm stacks

Toyota coil on plugs
T3 crank pulley with 32-1 trigger wheel/sensor

Few things changing on this over coming months lol...

[Jip86]

that where you get your timing gear modded Delazy?

[v33sonata]

That woudl be great! How didyou know you needed to rekey the crank? and where did u cut in the new key?

[v33sonata]

I plan on getting a set of custom pistons made for this set up and am not using the stock 20v ones. Wel I have access to 93 octane here where I live. Unless I wanted to run 100 or 150 leaded race gas which is not an intrest of mine. LOL

[v33sonata]

Perfect! now just need to figure out a belt