Cheap 4A-GE Stroker...

[LokiRx7]

I have been doing alot of research into this and I am sure a few board members have gone through with the 7A-GE conversion.

Alot of people claim that the 7A-FE wont be capable of the revs it will need to produce power, because the G style head is optimized for high rpm breathing. However, I have flow charted the 4A-FE, 7A-FE, 4A-GE, and 7A-GE and drawn loose conclusions based on patterns that I saw.

By adding .2 liters of stroke, the engine flows more air. Therefore using the 4A-GEs peak power and torque rpms as examples the 7A-GE conversion flows more air at those given rpms than the 4A-GE. So therefore obviously the 7A-GE reaches its peak power and torque earlier and at a lower rpm than the 4A-GE. This is all hypothetical of course, I havent tested any real engines but I am using alot of "racers math" that people trust when building an engine for a given application.

The 7A-GE should reach peak power 3-500 rpms sooner than a 4A-GE which means spinning the bottom end out to around 6000 - 6200 give or take. Now for a daily driven car (it isnt going to be, but I want to build it to last anyway) A 7A-FE could take that kind of beating, but lets say I want to do it on a fairly regular basis, say two or three times a week it sees a few really hard runs. Obviously I will be shifting out around 7K territory to take advantage of peak power and drop back into my power band. Would you trust a set of brand new OEM 7A-FE rods? Or would you spend the extra cash for a forged set? I dont think that would be too much to ask from a brand new set of Toyota rods, but I dont want to have to take it apart again, or walk down the freeway picking up chunks of block...

If I dont have to overbuild it, if Toyota did a fine job, I dont want to waste money. I am looking for people with experience, not people with opinions. I have plenty of those, and they just dont help the way facts do....

I am not sure this is the route I am going to go, but its a hell of alot cheaper than a 20V or a GZE, and I really dont need the wiring hassle. I am capable of it, but I just dont want to go tearing up my perfectly good harness.

[LokiRx7]

Nevermind, I found an Austrailian site with the info I needed.

All my calculations seem spot on, on an aussie toyota forum there is an interesting discussion about 20V 7A-GE's and it seems the OEM 7A-FE rod is good until 7500. To have any sort of relaibility you want to keep the revs under 7200, anything over 7500 is a death wish.

Shot peening and ARP bolts help as well (not needed if you keep it under 7500), also anyone that needs to know, use the 4A-GE pistons, NOT the 7A-FE pistons. For boost, you NEED forged rods, otherwise your wasting money on them.

[F0Bman]

7AGE is awesome for power. And if you're really adventurous go for 20V head.

[OldSkool]

What we need is internal engine dimensions so we can compare sizes to known cheap
forged engine parts. I have found numerous parts for a prior american engine series
and saved mucho $$$ over custom and "factory" racing parts. US engines are a bit easier tho

[fastrax203]

I just picked up a 7A-FE from the local Pick n Pull (block only of course haha). I'm going to be doing a 7A-GE 20V Build, it's going to take some time as I just finished my 20V swap in my AW11, but slowly but surely it'll be done. Plans are:

'95 7A Block
AE111 20V 4AGE Head
Crank cryo treated, lightened, knife edged and vibration stress relieved
Belfab H-Beam Rods
11.5:1 Pistons (toda)
288deg 9.0mm lift intake (toda)
272deg 9.0mm lift exhaust (toda)
valvetrain upgrade (toda)
Technotoytuning Velocity Stacks

This should run almost perfect on a blacktop ECU with maybe some GZE injectors and an afc-neo to lean out the injectors at idle. I imagine the engine should rev to 8k no problem setup this way.

[Raptor13x]

Originally Posted by LokiRx7

Nevermind, I found an Austrailian site with the info I needed.

All my calculations seem spot on, on an aussie toyota forum there is an interesting discussion about 20V 7A-GE's and it seems the OEM 7A-FE rod is good until 7500. To have any sort of relaibility you want to keep the revs under 7200, anything over 7500 is a death wish.

Shot peening and ARP bolts help as well (not needed if you keep it under 7500), also anyone that needs to know, use the 4A-GE pistons, NOT the 7A-FE pistons. For boost, you NEED forged rods, otherwise your wasting money on them.

7500rpm is really really low for a 20v. If it can't reliably handle at least 8500rpm, why bother?

[LokiRx7]

Originally Posted by Raptor13x

7500rpm is really really low for a 20v. If it can't reliably handle at least 8500rpm, why bother?

Those rpm numbers are what they found the OEM rods could handle. The guys that actually had the 20v 7A-GE's had forged internals.

Besides, even at 7500 rpm it would make more power then a 1.6. There seems to be a common misconception that just because you cant rev them as high you wont make as much power, not true. The displacement difference is such that the 7A-GE makes its power sooner because it is flowing more air at a lower rpm. Therefore you dont need to rev it as high to make the same power as a 4A-GE.

If you are looking for serious power gains, then odds are you will opt for cams that breath better at high rpm. Well if you can afford cams you can afford forged rods. And you should opt for the forged rods if you plan on making a serious performance engine. If you are looking for a small increase in power from stock and a good bit more torque, then the OEM rods are fine.

That is why with a 16v or 20v head a 7A-GE is actually a good way to go to add some low end grunt, if its built right it will outperform its 1.6 liter counterparts.


EDIT ::

This isnt exact but its fairly close, all you have to do is figure out how much air they flow at a given RPM then you can find at what RPM they flow the same amount of CFM's After seeing a few dyno graphs and talking to individuals who daily drive these engines and built them, this is fairly close to what they are making on stock 7A-GE's.

16 Valve
4A-GE Peak HP @ 6600 Peak Torque @ 4800

7A-GE Peak HP @ 6000 - 6100 Peak Torque @ 4200 - 4300

20 Valve
4A-GE Peak HP @ 7400
7A-GE Peak HP @ 6800 -6900

There you can see for a 20 valve 7A-GE 7500 is way more than enough. And if you want to rev it higher, all you need is forged rods and supporting modifications and the sky becomes the limit.