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4af engine modifications idea/problems

25K views 24 replies 10 participants last post by  howellsautoshop19 
#1 ·
I know people have compiled some info out there for the 4afe and the 4age but there seems to be little on how to modify a 4af engine. I know that it is not a normal engine to modify but i dont think i am the only person who wants to modify this engine. I have considered doing the 4age swap but right now im trying to see how much Hp i can get out of a 4af. Here is the this of things i can do

A engine rebuild kit at http://www.rpmmachine.com/shop/index.php?l=product_detail&p=5457

Then an Aftermarket exhuast http://www.streetperformance.com/part/pacesetter/exhaust-header/1403702-70-1153.html

Then a Weber DCHOE 32/36 I hope to put a scoop to for the air into the carb.

Now i am not sure about the flywheel..... will a 4age gts flywheel fit onto a 89 corolla sr5?

Anyway i was wondering What else i could do to the car and what is the Highest Hp someone has gotten out of it. I hope to tackle this whole things as a senior project and document the whole process on this forum as well. :D
 
#2 ·
hey
i have spent money onto my 4af engine headers, exhaust, aftermarket air filter etc, there isn't much else you can do to the 4af engine. I could've spent the money on doing a 4age 20v conversion, i also thought i could be different but im still never going to get the amount of HP that a 20v would put out.
your best bet would be just to do the conversion and spend your money wisely, mind you i have enough power to blow the socks off an Altezza.
expect the unexpected. :thumbsup:
Good Luck.
Greg.
 
#3 ·
No, the 4A-GE flywheel will not bolt to the 4A-F crank. The 4A-F uses a 6 bolt flywheel/crank. The 4A-GE uses a 8 bolt flywheel/crank.

But why would you want to change the flywheel? Try to lighten your current flywheel.
Give the head a good port job, get a nice exhaust header. Maybe fit a less think multilayer steel headgasket to up the compression just a little bit.
Maybe you van even see what can be done about the camshafts.

I guess It'll put out a little more. ;)
 
#19 ·
anything is possible as you might already know given the right amount of cash. that said the best way and cheapest way of getting power out of a 4afe would be turbo. theres 2 ways of going about the management. both will end up costing the same, (well if you dont blow it) 1st. is to use a fmu, with slightly up rated injectors. team that up with a msd btm just to be safe (most people recommend low boost with the use of fmu because they raise fuel pressure). 2nd is megasquirt (you can basically run anything with this).... they both will end up costing around the same to setup.

if your going to swap i would not swap in anything other than a gze or blacktop. the dynos for most silvertop show they are only around 120whp engines.
 
#6 ·
You arent gonna double the hp with a silvertop or a 16V swap either...:facepalm: You really didnt read what anyone else was answering to you except about the swap, did you? In your first post you want to keep the 4A-F, now you wanna change it... Make up your mind first, stick to it and then start to asking for advice.
 
#24 ·
You arent gonna double the hp with a silvertop or a 16V swap either...🤦 You really didnt read what anyone else was answering to you except about the swap, did you? In your first post you want to keep the 4A-F, now you wanna change it... Make up your mind first, stick to it and then start to asking for advice.
Shave the block and shave the head and use 4afe 3rd gen piston and conrod the compression ratio is up port and polish the head modify your carburetor
 
#8 · (Edited)
well first of all i believe there is a 7afe head that flows a lot better than the 4afs but is the design the same for valvetrain? i dont know, anyways a rebuild with lighter rods higher compression pistons + balancing and big cams would get you fair power

or you could go with forced induction since high compression pistons for a 4af would probably have to be custom made while you can use forged low compression pistons ment for the 4age since you should have to worry about valve cut outs with a piston that has a pretty deep dish

to double the hp you will need a better flowing head/exhaust/intake a built block, massive head work probably with big cams and done up valvetrain and some form of engine management

even then it would be easier to double it if thats even possible if you went with a 7afe or 4age and built a 4age

i think to modify a 7afe head might be cheaper than a 4age since you have rockers and dont need to worry about flipping shims with big cams, rockers could pose another problem at high revs or with big cams but i dont really know since i have no experience with them
 
#13 ·
there are many turbo setups that run carb's but im not sure if it has been done on a 4af? and they wouldn't be very common because the carb has to be setup as a "blow through" to be able to take the boost from the turbo and into the cylinders. there is no point turboing a 4af when you could spend an extra $500-$1000 on a better engine and use the money for the turbo setup on that engine.
 
#14 ·
Just encase it in a pressure box, then figure out what jets you need. Easiest way to do it.

That wouldnt even cost much. Efi fuelpump, regulator for carb pressures with boost reference, the pressure box and tuning, turbo and manifold stuff. prob less than 500 bucks if you use used parts.
 
#21 ·
I am not the same person as the original post..
But i did end up recently fully rebuilding a 4AF and put down strong numbers without that much money into it..

It cost me under a grand to fully build the 4AF, which to me was worth it.. Honestly if you have the time, space, and patients to redo everything you can go 20V with computer, wiring, transmission, and everything else.. i didn't because it wasn't worth it to me.. But.. to each there own.. I was more interested in the challenge.. Issue is most people on here, have never pulled one completely aparts, and didn't or don't know the difference internally..

One of the major issues is you have to take yours apart to figure out what size Connecting rods you need, and Pistons you need.. the wrist pins are different sizes in different 4AF motors.. Since mine was a 4AF that i had no idea if it was actually the original motor or not.. i pulled it, ripped it apart, and figured out what was what..

I ended up with a 11:8.1 compression ratio.
New valves, guides, seats, and ported the head.. (dremel based on online specs) All the parts i bought used from ebay and cleaned everything up.. Purchased new only gaskets, and hardware from ARP.

Car is running a Weber Carb conversion.
On my 4AF all the internal parts were identical to the bluetop with the casting on the block matching the 3 rib small port. The only difference i could find was the conrods, but i replaced the rods, and the pistons anyway.. used a .40 head gasket, which also upped the compression ratio..
Customized some 7AFE cams, and put them in, they have a longer duration, which helps feed the engine, and let her breath..

End of the day it made 135WHP.
which is higher than a stock 20V at the wheels..


My original plan was to build a hybrid of the 4AGE head on the 4AFE block, but the more i looked into it, the more customization was required, and i didn't want to jump through all those loops.. That being said i have been looking into adding DCOE carbs on my 4AF, and have a machine shop looking into seeing if they can make me a custom manifold..

You need a fuel pressure regulator, and i would suggest an external fuel pump as well to keep the pressure more regular.. the mechanical pump isn't precise enough..

And while you can do most of this with the engine in the car, it's a lot easier to pull it and do it that way..

Engine lifts can be had for 150.00 and it's worth it..
 
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