7AGE 20V 6 speed

**Bazooka** · 12-03-2007, 03:01 PM

Hi All,

I am considering a conversion into an AE112 Corolla. I can source a Blacktop 20V 6 speed half cut to do so but am considering keeping the 1.8L bottom end. Now this car is to be kept as a daily driver and will not be used for racing or (much) hard driving. I would like things to be kept stock and look factory under the bonnet. I have read up a little and it seems that the bottom end should be fine for what I want with just a little balancing and strengthening (shot peening?)
What I cannot find much on is mounting of the gearbox into the vehicle as i would assume this to be different to the standard 5 speed. Anyone had much to do with these 6 speed gearboxes? Also what timimg belt needs to be used? I have found reference to the use of a Porsche timing belt for use with the 16V head but nothing concrete on the 20V head. Can anyone confirm this?
Is there anything else I need to consider? Are things like the clutch and flywheel going to be a drama?

Cheers

**4agte** · 12-03-2007, 03:24 PM

they are still a c series box right so id assume the corolla driveshafts would bolt straight but to the inner driveshafts

assuming the gearbox mount is the same it should be a bolt in affair

JP · 12-03-2007, 04:58 PM

use the gearbox mounts from the frontcut and the 6-speed should bolt in.

Use your 7A flywheel and a 212mm clutch setup.

What pistons are you going to use? The blacktop pistons on 7A rods will put the compression through the roof.

**adamaw11** · 12-03-2007, 05:02 PM

have you found this yet?
http://www.turbofast.com.au/mr2.html

says he used the 20v timing belt, but had to stuff around and modify a few bits and pieces

**Bazooka** · 12-03-2007, 05:12 PM

Thanks JP,
From what little I have read putting the blacktop pistons onto the 7A rods was the way to go. What sort of compression would this give me? I assume I am looking for something around the stock compression figure.
Adam, yes I know about the Ray Hall MR2 but from my reading it seems that others have done the same using a different belt without all the other modifications being needed.

I'll keep looking

JP · 12-03-2007, 05:27 PM

on a 16V 7age it's easy to get the cam timing back where it needs to be with some adjustable cam gears.

Not quite so easy on the 20V unless you want to lose the VVT operation by installing some TODA or speedracer cam gears.

You're starting with 11:1 compression ratio in the AE111 4ag, I haven't done the maths for the ratio with the extra stroke of the 7a, but with the same combustion chamber volume I'd expect it to be over 12:1 by a fair amount.

**Poggy** · 12-03-2007, 10:19 PM

you'll need to use the 4age accesorys etc

**4agte** · 12-03-2007, 11:11 PM

ive seen a 20v turbo 7age before so it can work

**Bazooka** · 13-03-2007, 01:28 PM

OK so does anyone know what pistons I should be using and what timng belt is going to work with this setup? At least all I probably need to know is how many teeth the belt would need to be as I can find something from there.

**terryo** · 13-03-2007, 09:05 PM

I have done several of these engines & can supply the correct belt You also need a custom forged piston, to make it all work correctly. The 7A rods are the weak link and I usually change them for forged ones. not a cheap conversion. www.roadandtrack.net.au

**30psi 4agte** · 13-03-2007, 09:19 PM

Terryo: there is some interresting stuff on that link.

Whats with the 3/4 groove bearings ??

**Bazooka** · 13-03-2007, 11:12 PM

Sorry Terry but I did not even give you a thought. I will call you tomorrow to discuss

I had no idea you frequent this forum either haha

Cheers

**Starfire** · 15-03-2007, 08:44 PM

Once you measure the required length of the timing belt and it's width and tooth profile, any spare parts shop should be able to find the required one for you.

They come in an amazing array of lengths.

**DX20VT** · 16-03-2007, 07:46 PM

from what i found with this type of conversion,

If you use the 20V head,
the 16V belt will fit and line up the cams If you use the Blacktop oil Pump and Hydraulic Tensioner.

The 7A engine has the combustion Chamber more in the pistons than in the head and so the pistons do not reach the top of the bore, and so the compression is never as high as you think, most of the time it ends up too low.

**Bazooka** · 16-03-2007, 09:47 PM

Thanks guys but I have Terry getting back to me on what I need. Apparently he has done a few and tried all different pistons for this conversion. He mentioned something about Astra pistons but will wait and see what he comes up with. Will let you all know (if Terry doesnt want it kept secret) as to what should be used.