The actual potential of the 4AFE cylinder head?

mr2mk1hero
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The actual potential of the 4AFE cylinder head?

Postby mr2mk1hero » Thu May 07, 2020 12:38 am

Hello my good 4age people, long time no see!

I have a pretty serious and maybe somewhat complicated question to ask, but I know this forum has more than a few individuals capable of providing some valuable input.

You might know the car and engine I'm currently running. The bike carb 4age in my aw11 https://youtu.be/daqmPnEYMfk
https://youtu.be/rvGsjKa_6uM

These are old videos, and last year on the dyno I managed to churn out 130hp at the crank. I have been doing some more tweaking this spring and discovered a few power stealing mistakes and played with the jets some more and I'm fairly certain I'm around 140-145hp at this point. But power was never the goal and is a bit irrelevant for this build. The goal was a responsive, rev-happy engine that's fun to drive- And that it indeed is, even more than I expected. The mpg isn't great of course, but pushing this little momentum car on a twisty road is beyond satisfying for me, and the soundtrack never gets boring. I'm really in love with it at this point.

But, I'm eager to start building something again. I won't be removing this engine and transmission from the car because I want to keep driving it for another year, two or maybe even three, so my plan is to slowly build an entirely new engine on the side and then just swap it over when it's ready. And maybe put the old engine and transmission in a lightweight starlet/corolla whatever. We'll see. And just like I wanted to do carbs and learn about carbs now I want something new yet again and I want to try a turbo build. As some of you may know I'm living in the Balkans and 4age engines have become incredibly scarce here. It's very very hard to find one, in any condition. So to start my build I decided to hunt for a 2nd gen 4AFE instead so that I could use the 7 rib block from that engine. My plan for the turbo build is fairly ambitious and I'm interested in building a stout, overbuilt engine that can take some decent boost. I'll go for the hardware with the best bang for buck and invest heavily in software. A standalone ECU with all the sensors, knock monitoring, several switchable maps etc. My plan is to use the 42mm fully counterweighted 4age crank, aftermarket forged rods, and gze low compression pistons in the block. Original plan was a bigport head, but the 4afe engine that's coming today got me thinking... and here's where this post gets a bit complicated.

What's the ultimate potential of the 4afe head? Provided a strong fresh bottom end as described above, can the 4afe make power if done right? I know a definitive answer to this could only be provided by a lot of empirical testing, a flow bench etc. But that isn't realistic for an enthusiast so let's talk theory.

Here's what I know: The angle of the intake port onto the valves is better on a 2nd gen 4AFE than on a bigport 4AGE, or the smallport. The size of the intake port and the size of the exhaust port is worse of course, and the casting lines etc might be a bit inferior? The combustion chamber is smaller, but is it worse for making power provided one can reshape it properly? What I do know from research is that flame front propagates slower in the 4AFE than in the 4AGE, which is usually a bad thing for power, but I'm not very experienced with boost and am not sure whether forced induction will offset that somehow? The big question is, can extensive smart porting minimize the negatives and make full use of the positives and bring the 4AFE on par, or even beyond the bigport 4age for a forced induction build?

I have carefully read through OSTs porting threads, both on Grunt in 2010 and the more recent 2nd gen 4AFE in 2017. Those really offered a lot of insight and that oil drain near the number 1 exhaust port is concerning. I also want to say thank you to OST and his incredible porting threads he has been posting over the years. Only after being in the car community for a few years have I come to realize how incredibly valuable and educational they are. They are free for everyone to see and for anyone who has the attention span to observe are an incredible learning resource, with all the right images and all the key things neatly pointed out. The effort of shooting, sorting and posting such an endless number of images and explaining them is no small feat, and it's all available for free. Thank you OST.

Now for the all-important question, what are my actual power goals with the build? Just like my current build, this would be a street build, mountain road driving fun car, and my plan is two-three different switchable fuel/ignition/boost control setups. The first is what I will be driving on 75% of the time, and the power goal there is 200 hp, give or take 10hp. I'm not really obsessed with numbers, and the aw11 is fast enough even with low hp in my opinion. My priority is how the car feels, so for it to be entertaining to drive I'm looking for fast spool, but also a decent top-end (aren't we all?) The first setup will be mild without straining the engine and should be capable of decent mpg. (I was even considering LPG, a million different companies provide that here in Europe) The other setup will be there for "demonstrational purposes" and occasional fun straight line sprints and ego-tripping attempts to embarrass expensive modern cars (latent inferiority complex?) And I would like to see 280-300 hp on that second setup. I know a turbo that can cover the relatively large span between the two setups will be a tough choice, and won't be "perfect" for both setups, but I'm willing to work on the first setup first and only attempt to chase 300hp if I can do 200hp reliably and consistenly. The first setup can be categorized as having priority. My plan is to start with a ebay/clone t28 turbo, and get a more serious, modern turbo afterward. I always wanted to get my hands on one of those cheap eBay ones and just try it for fun. I really like cheap things.

So all of this brings us back full circle to the 4afe. Can the F head do 300hp provided I give it the right prep? I would actually enjoy a F head build more than a G head one because it would be something new and different, both for me and the community probably, and provide new insight into the often-overlooked economy engine. Maybe given the right bottom end and supporting environment the underdog F could shine? I know there was a guy in AUS who posted a thread on his corolla with a 4afe that allegedly made 300hp on the dyno, but it was a drag racing setup and the turbo looked absolutely giant to me. Or maybe doing the F is a path to regrets and wasting time on a head with geared together cams and a pathetic aftermarket?
Check out my YouTube channel: https://www.youtube.com/channel/UCwosUn ... xtqkNJ3Fbg
Check out my blog: http://www.driving4answers.com/
Heaps of 4A-GE and MR2 mk1 aw11 content on both.

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oldeskewltoy
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Re: The actual potential of the 4AFE cylinder head?

Postby oldeskewltoy » Thu May 07, 2020 7:39 am

than you for the kind words......

If you have been doing your homework, you likely bumped into a few Bill Sherwood mentions, and his goal for a 240hp F headed 4A. WHICH 2nd gen F head do you have? In the world somewhere (unsure of which market) Toyota sold a true 4 port F head.... You can double check with Bill, but I believe that is the head he intends(intended) to use in his build.

Bill's page: http://www.billzilla.org/starleteng.htm

Bill's head...

Image



Head from OST-044

Image



Additionally, if "F" heads are truly plentiful, you may want to cut up a few and look at where there is room to work/port the different heads.
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

mr2mk1hero
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Posts: 134
Joined: Mon Jan 26, 2015 2:40 am

Re: The actual potential of the 4AFE cylinder head?

Postby mr2mk1hero » Thu May 07, 2020 3:55 pm

The engine was supposed to arrive today but it didn't. Here's a pic of it until it arrives tomorrow: Image
It's from a 1996 European Toyota Carina E (gen 3 they call it here), so it's a 2nd gen 4af and pretty recent by 4A standards.
I did read that Bill's page a few times and I sent Bill an email a few days ago too, I hope he sees it.
As far as I can see the only difference between Bill's head and OST-044 are those big dividers in the port? Or am I missing something else?
I'm expecting the engine tomorrow, so I'll remove the intake manifold and see what I have.
I was thinking about cutting up a few F heads, but they really aren't THAT plentiful, but if I find another 2nd gen one, it would definitely be fun to cut up. I have a spare bigport 16v too, could cut that up as well and make some really nice documention and comparisons. We'll see. Right now I'm hoping I have the bill F head, which means minimal work on the intake ports, enlarging the exhaust ports a decent amount and doing something to the combustion chambers. The chambers are honestly the biggest mystery for me because beyond deshrouding the valves and removing any sharp edges that are potential hot spots I really don't know what else I could do?
The 240hp naturally aspirated 4ag Bill did/is planning to do makes me think that 300hp on forced induction should be easy, but I'm really having a hard time believing 240hp NA hp with an F head is possible, especially when Bill wrote on the page the engine should still behave normally for driving around town. I mean NA 4aGes with "only" 200hp are horrible for driving around town and making that sort of NA power requires giant cams which leaves the bottom end torqueless, no matter what you do. It' s still a very oversquare NA 1.6 four cylinder. But I know less than Bill so maybe 240 hp is possible.
Check out my YouTube channel: https://www.youtube.com/channel/UCwosUn ... xtqkNJ3Fbg
Check out my blog: http://www.driving4answers.com/
Heaps of 4A-GE and MR2 mk1 aw11 content on both.

Bempa
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Joined: Mon Sep 28, 2015 11:32 pm

Re: The actual potential of the 4AFE cylinder head?

Postby Bempa » Fri May 08, 2020 1:41 am

This is going to be very interesting to follow, I do belive there is som hidden potential in the F-series heads, especially with turbo. And i have been longin myself to do an 4afe turbo build,

Cat cams can help you with camshafts, there is also a Finnish guy on Youtube that has done alot work to an 4afe, I can´t remeber his name but i do believe you can find him by searching for "4afe itb´s"

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mr2mk1hero
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Joined: Mon Jan 26, 2015 2:40 am

Re: The actual potential of the 4AFE cylinder head?

Postby mr2mk1hero » Sat May 09, 2020 8:52 am

Ok engine is in
Image

I didn't have much time to mess around with it, but I couldn't resist removing the intake manifold to see what kind of ports I have.
Image
So as you can see I have the same thing as OST-044, which I guess isn't optimal but it's what I expected. The true 4 port head seems to be an Asia only thing. The port angle onto the valve really is a lot better than the bigport in my opinion. You can actually see most of the backside of the valve when you look at the ports. The oval-square shape combo isn't ideal, but I think it's not too bad either. The intake manifold itself on the other hand is definitely not performance oriented. Weird shape of runners, small plenum, but I understand why it turned out like that. They wanted the last part of the runners to enter the head at an angle suitable to the port - this requires the manifold to be in a physical position higher than the head, and for a mass produced fwd car, that's an issue and probably doesn't fit under the hood. So I'm definitely going for a custom intake manifold if I stay on the F path, as aftermarket options don't exist. There might be fitment issues underneath the AW11 engine lid, but I'm willing to modify the lid too.

But there is a lot of good news too, three pieces of it in fact.
1. The engine comes with a factory crank position sensor. The joy! No giant trigger wheels and crank sensor brackets that forced me to learn cad drawing. A nice elegant solution is right there from the factory.
2. Factory knock sensor installed too. Yay. No second guessing the optimal position for the sensor, no drilling or tapping the block. Yay
3. This engine has a nice PCV system, the kind with the valve that you find on more modern engine. Not the pseudo-pcv of the 4ag bigport that can only be turned into a vent into atmosphere catch can and that's it. Even after modification and a custom intake manifold the factory pcv can stay and provide actual suction of crankcase pressures, which is always a good thing.
The crank and flywheel are of the 6 bolt type as expected. Exhaust manifold is bent tubes, look really impressive for an economy engine, a lot better than the half-a-ton cast one on the bigport.

So far so good. I'll take a more detailed look at the engine soon, but this is all I had time for now.
Also, a question came to mind as I observe and thought about the potential forced induction build of the 4af. The head gasket. Can 4ag gaskets be used? I would prefer some sort of mls gasket if possible. I found a company in South Africa that offers a decent steel option for the 4ag, which is good too and led me to believe that 4age gaskets aren't compatible. Am I correct?
Check out my YouTube channel: https://www.youtube.com/channel/UCwosUn ... xtqkNJ3Fbg
Check out my blog: http://www.driving4answers.com/
Heaps of 4A-GE and MR2 mk1 aw11 content on both.

jinx
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Re: The actual potential of the 4AFE cylinder head?

Postby jinx » Sat May 09, 2020 10:00 pm

stumbled on a toyonation thread many years back. Have pix on my pc still
SR20 T25 turbo on a stock 4AF, with only a FMU. Full weight automatic 94 corolla ran a 13.8sec 1/4 mile!
Fast as any other, for what it was. Didn't live long due to lack of tuning.... as the owner expected
I'd leave the 4AF stock/untouched, just turbocharge it and decide on tuning plan. Obvious good potential

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