Easy way to get your 4AF sounding wicked! (guide inside)

[darth-grantius]

Hey guys. First of all you remove this cover:



Then take the top screw off and screw it onto here:




Ok now all the air is still filtered and under load in second and 3rd in sounds wicked!

After this my fuel economy increased - it sounds wicked and top end is much more power!

Also the engine runs colder, starts better and gets colder air intake.

[Flashmn]

Your engine would run hotter, as the tube from the front acts like an CAI...

[Kiwi-Corolla]

It may sound good, but it will be affecting your performance due to the filter sucking in more heat, as mentioned above. It's basically just like installing a short ram intake on a EFI engine. However I don't imagine that you'd be drag racing your 4A-F or trying to break land speed records, so the loss in performance shouldn't really be an issue. I'd recommend running some tubing from the remainder of the intake snorkel to the air filter, just to aid in airflow. Either that or keep an eye on your temperature gauge during long drives . Alternatively, rip that sucker out, do a 4A-GE conversion and hear what a truly wicked intake note sounds like

EDIT: To be more specific in regards to the loss of performance, you will see some slight gains in the top end, but this will result in a loss from the low end. The reason you're using less gas is because of the warmer air charge. Warmer air equals less fuel and less power. Colder air equals more fuel and more power. The carburettor cover basically acts as a heat-shield, much like the one on your manifold. The moment you remove it, the temperatures increase. I experienced the exact same thing when I had a short ram on my EFI 4A-FE, until I upgraded to a CAI. By no means and I knocking what you've done, and if you're personally seeing positive results from it then that's great, but the things I mentioned are worth considering. Would be interesting to see a video of what it sounds like if you ever get the chance

[darth-grantius]

Originally Posted by Flashmn

Your engine would run hotter, as the tube from the front acts like an CAI...

Wrong.

If you look, there is a pipe from the exhaust manifold that sucks in hot air, and I think its jammed open.

[darth-grantius]

Originally Posted by Kiwi-Corolla

It may sound good, but it will be affecting your performance due to the filter sucking in more heat, as mentioned above. It's basically just like installing a short ram intake on a EFI engine. However I don't imagine that you'd be drag racing your 4A-F or trying to break land speed records, so the loss in performance shouldn't really be an issue. I'd recommend running some tubing from the remainder of the intake snorkel to the air filter, just to aid in airflow. Either that or keep an eye on your temperature gauge during long drives . Alternatively, rip that sucker out, do a 4A-GE conversion and hear what a truly wicked intake note sounds like

EDIT: To be more specific in regards to the loss of performance, you will see some slight gains in the top end, but this will result in a loss from the low end. The reason you're using less gas is because of the warmer air charge. Warmer air equals less fuel and less power. Colder air equals more fuel and more power. The carburettor cover basically acts as a heat-shield, much like the one on your manifold. The moment you remove it, the temperatures increase. I experienced the exact same thing when I had a short ram on my EFI 4A-FE, until I upgraded to a CAI. By no means and I knocking what you've done, and if you're personally seeing positive results from it then that's great, but the things I mentioned are worth considering. Would be interesting to see a video of what it sounds like if you ever get the chance

Again, there is a pipe that runs from the exhaust to the intake, and i can physically see that my temperature gauge reads less with the cover off.

I will try and get a video up, I love it in third when it hits 3200~rpm you can feel it

[Kiwi-Corolla]

Originally Posted by darth-grantius

Again, there is a pipe that runs from the exhaust to the intake, and i can physically see that my temperature gauge reads less with the cover off.

I will try and get a video up, I love it in third when it hits 3200~rpm you can feel it

Yeah the pipe that enters the manifold's heatshield is a strange idea, but the purpose of that is to push the heat that lingers around the manifold down towards the ground as the air gushes into the intake snorkel. The only time that it would suck in the hot air from the manifold to the air filter is when it's sitting at idle or if you're crawling slowly in rush hour traffic. Looking forward to seeing the video

[Flashmn]

Yeah the pipe that enters the manifold's heatshield is a strange idea, but the purpose of that is to push the heat that lingers around the manifold down towards the ground as the air gushes into the intake snorkel.

If you look, there is a pipe from the exhaust manifold that sucks in hot air, and I think its jammed open.

The pipe to the exhaust has a valve in it, it changes air intake to next to the front headlight in hot climate and during winter you get air from the exhaust manifold. It aids in avoiding carb icing, which is a problem in downdraft carbs as the manifold makes a 90degree angle.. I never had that on my 4A-F as it was a tropical version. If the valve isnt working, then I'd fix it.

Either that or keep an eye on your temperature gauge during long drives

Air intake wouldnt have anything to do with engine temperature. The engine is watercooled, thus it runs at a relatively steady temperature regardless.

[Kiwi-Corolla]

Originally Posted by Flashmn

The pipe to the exhaust has a valve in it, it changes air intake to next to the front headlight in hot climate and during winter you get air from the exhaust manifold. It aids in avoiding carb icing, which is a problem in downdraft carbs as the manifold makes a 90degree angle.. I never had that on my 4A-F as it was a tropical version. If the valve isnt working, then I'd fix it.

Interesting, I wasn't aware of that. I had an old carburetted Civic once and it had the same sort of design with the snorkel branching off the the exhaust manifold's heatshield, but certainly didn't have any sort of valve inside. Makes sense to have one though. Although here in NZ it doesn't get very cold, unless you live in the south island.

[Flashmn]

I think it gets cold enough. Carb icing occurs about at, I'd say 5C-> -5C when the air has still humidity in it, and due to the venturi effect the moisture in the air starts to ice up. Really cold weather is so dry it doesnt really happen. So you have that snorkel to aid it, its called a HAI valve on a toyota (hot air intake) and you can see it has a vacuum line going to it from the carb.

But to the OP, you do also realize that theres a coolant running through the intake manifold, that heats up the manifold aswell, theres a port on the head and then theres a bypass line on the thermostat housing that goes via the manifold into the waterpump tube. Dont remove those lines, you'll cook your engine as coolant isnt going to circulate that well without them, BTDT and ended up with a blown headgasket..

And another thing, that airfilter box is fairly restrictive on the carb model, you'll get about 10hp (dyno proven) when you remove the filter box. I had a glitch in my vocabulary, the engine doesnt run hotter, the intake air does. If you really want to horse around, you can put a CAI on the carb too, I had a short ram intake on mine. I think a 1992ish Lite ace has a similar carb, so you can get the filter adapter from one (its an L shaped thing) that you can use to make a CAI intake... if you want that is...

[darth-grantius]

Originally Posted by Kiwi-Corolla

Interesting, I wasn't aware of that. I had an old carburetted Civic once and it had the same sort of design with the snorkel branching off the the exhaust manifold's heatshield, but certainly didn't have any sort of valve inside. Makes sense to have one though. Although here in NZ it doesn't get very cold, unless you live in the south island.

Im in New Zealand too, and it doesn't freeze up the carb at all.

[darth-grantius]

Originally Posted by Flashmn

I think it gets cold enough. Carb icing occurs about at, I'd say 5C-> -5C when the air has still humidity in it, and due to the venturi effect the moisture in the air starts to ice up. Really cold weather is so dry it doesnt really happen. So you have that snorkel to aid it, its called a HAI valve on a toyota (hot air intake) and you can see it has a vacuum line going to it from the carb.

But to the OP, you do also realize that theres a coolant running through the intake manifold, that heats up the manifold aswell, theres a port on the head and then theres a bypass line on the thermostat housing that goes via the manifold into the waterpump tube. Dont remove those lines, you'll cook your engine as coolant isnt going to circulate that well without them, BTDT and ended up with a blown headgasket..

And another thing, that airfilter box is fairly restrictive on the carb model, you'll get about 10hp (dyno proven) when you remove the filter box. I had a glitch in my vocabulary, the engine doesnt run hotter, the intake air does. If you really want to horse around, you can put a CAI on the carb too, I had a short ram intake on mine. I think a 1992ish Lite ace has a similar carb, so you can get the filter adapter from one (its an L shaped thing) that you can use to make a CAI intake... if you want that is...

All I did was remove that top cover.

Not touching anything else.

Im thinking of removing the whole filter set up and either putting a mushy on it or get a L joint and some pipe to make a CAI.

[MKEAE92]

Used to do something similar with my dad's old's with the 455 in it. Thought it was so cool when I could hear the secondary's open up to feed that monster. Later in my years of actually working on cars - I realized the only difference was what I heard!

[SCT]

Even though my silvertop is not yet installed in my car......... The sound of ITB's. Unfortunately, I would be running a turbo so I probably couldn't use velocity stacks on them... or can I....

[darth-grantius]

Originally Posted by SCT

Even though my silvertop is not yet installed in my car......... The sound of ITB's. Unfortunately, I would be running a turbo so I probably couldn't use velocity stacks on them... or can I....

Why turbo a 20v?

Harder to find parts plus it has higher compression....


Anyway,

It does gain 10hp as said above.

[SCT]

Lowering the compression...