Wednesday, April 22, 2009

A Guide on 4A-GE Conversion into RWD Daihatsu Charmant

I've been wanting to write this up for a long time. The reason is that i am looking for a workshop to help me put the 4A-GE on The Dog and i don't want to have to explain each time all my plans to the workshop owners/mechanics. I just have to guide them to this page and let them read. Of course that means they have to be familiar with internet and that actually also is one of my requirements for the workshop since i will be keeping in touch with them from a long distance and i may need to send them pictures or links. They even have to understand English since i am using it now..

Disclaimer. I've never done any engine conversion. This is just a summary of my internet research done so far which may be wrong. You may know better than what i write here so if you do, please share (and if you've worked on 4A-GE swap before, most probably you do) .

Ok, so here we go..

My 4A-GE is made for FWD setup and as you know, Charmants are RWD. So, there are some things you need to do to put a FWD 4A-GE as RWD engine on Charmants. These are some that i know. Take note take i am keeping the fuel injection. It's a slightly different story if you're opting for carburetor.

First of all, the first thing that always pop in mind regarding engine swaps is engine mounting. Charmants, mine at least, use 4A-C engine. This guarantees that 4A-GE will bolt on easily without any mods, welding, grinding or anything done to the engine mountings. Just use the old engine brackets from the 4A-C, bolt them on the 4A-GE short block and put the 4A-GE in. I may got confused between engine brackets and engine mounts. What i mean with engine mount is the thing that is welded to the crossmember while brackets are stuck in between your engine block and engine mounts. See Fig 1 below.
Fig 1

I will be using my old A/C compressor and i don't think my 4A-GE comes with the mountings. On my 4A-GE version, the A/C compressor is mounted on the exhaust side (passenger side). The same applies to my old 4A-C engine so you may be able to use the old A/C mounts on the 4A-GE. I won't be needing any Power Steering so that's one less thing to worry about. Heck i am even considering of not using A/C in the first place!

Unless i can get a good price for a good quality full exhaust system from the workshop, i won't have the exhaust worked on yet. I am planning on letting an exhaust specialized workshop built it. I already have a 4-1 extractors on my 4A-GE and that should keep the engine running while i move my Charmant to the exhaust workshop, albeit it would be very loud. One thing to note on 4A-GE exhaust on Charmants, the 4A-C has the exhaust ports on the driver's side (right hand side) while the 4A-GE has them on the other side, on the left. This means you need to reroute the exhaust pipes so that it pops out on the passenger's side. See Fig 1 above. Also, don't forget to make provisions for the O2 sensor boss. It should be as near as possible to the 4-1 junction.

I am not clear yet on what needs to be done for the cooling system. Rest assured that something needs to be done. I'll make some more research and update you on this one. I read somewhere you can use many parts from the old 4A-C like thermostat housing and stuff. One thing i know is about the radiator fan. You can't mount an engine driven fan on a FWD 4A-GE using the standard water pump or you'll drastically reduce the water pump bearing life. This means you need to use an electrical radiator fan. You need to work out a way to use the thermoswitch to drive a relay that in turn switches the fan on and off. There should at least be three sensors attached to the cooling system. One each for the ECU, water temp gauge and the fan's thermoswitch. I haven't figured which one is which since i can't have a look at my engine in detail yet. There's a good write up on the cooling system here and here.

My 4A-GE will have its throttle body air inlet facing the firewall without any mods done. Luckily i have the MAP sensor version so i have some options. Depending on the space between the firewall and the air inlet, you can either use a flat type air filter (if space permits) or if there's not enough space (or you have the AFM version) you need to "cut-n-shut" the intake manifold (or if you prefer, you can do it this way). You basically cut both ends of the intake manifold and swap the throttle body to the front of the manifold and weld a plate to shut the rear. See Fig 2 and 3 below.
Fig 2 - Cut n Shut Steps
Fig 3 - End Result
One important thing to remember on doing cut-n-shut is about the PCV. Though it seemed that the PCV hose was connected to the middle of the intake plenum, giving the illusion that it vents any pressure to AFTER the throttle butterly, it actually does not. The pipe on the inlet does not go straight into the intake manifold, it goes into a gallery on the inside of the intake that routes it to BEFORE the throttle butterfly. If you don't reroute the PCV hose, you'll block the pressure since it is now covered by a plate welded to where the throttle body was. Hence, if you're doing the cut-n-shut, make sure you reroute the PCV hose to somewhere before the throttle butterfly. Just weld a pipe on your air filter pipe for the hose to attach or use an oil catch tank. See Fig 5 and 6 below taken from here. They are from bigport manifold but it's the same case with smallport.
Fig 4 - TVIS Plenum Cut-N-Shut
Fig 5 - PCV Routing Gallery to Throttle Body
Fig 6 - PCV Hose Rerouting on Cut-n-Shut

You also need to find a way to hook a throttle cable and link it to your gas pedal.

You need to have a fuel return line. Carburetted cars like Charmants don't have it. You need to fabricate your own. EFI system has two fuel lines between the gas tank and the engine. One is to deliver fuel to the engine (fuel supply line) and the other one is to flow any excess gas from the fuel pressure regulator back to the fuel tank (fuel return line). Since you'll be producing more horsepower with your 4A-GE, it is advisable to use the old line as the fuel return and use a larger diameter pipe for the supply, not the other way around. 8mm should be enough as the supply line.

While you're fabricating the fuel supply line, prepare some way to install an electric fuel pump. There are two places where you can install your fuel pump. First one is inside the tank or the second is in the middle of fuel supply line. Personally i think in-tank fuel pump is more difficult to install. You need to prepare some way to hang the fuel pump inside the tank and prevent it from falling from movement and also most importantly is the electrical connection. It should be strong and no spark should ever occur from the connection. Electrical spark inside the fuel tank? Not a good idea, right? So i am leaning towards the second place; install it somewhere along the fuel supply line. Don't forget the fuel filter. See Fig 7.
Fig 7 - EFI Fuel Line Diagram

Which fuel pump to choose? Life is much easier with the invention of fuel pressure regulator. This device makes sure that constant fuel pressure is always present in the fuel rail, no matter how high the fuel pressure coming from the fuel tank. This means that if you can't get a hold of the fuel pump designated for your engine, you can use any fuel pump with at least the same flow rate and pressure capability. Any excess pressure will be handled by the pressure regulator.

Here's a simple calculation to find out your required fuel pump's flow rate, measured in liters per hour (lph). First you have to know what horsepower number are you aiming. In stock condition, my 4A-GE would produce around 140 hp. Use the following formula to output your required injector flow, taken from import tuner website.
Fig 8 - Injector Flow Rate Calculation

BSFC is Brake Specific Fuel Consumption, use .50 for normally aspirated engines and use .60 for forced inductions. On my case, 140 hp would require an injector flow rate of around 230 cc/min. Quite a close number to the value shown for stock injector flow on Bill Sherwood's page here, 235 cc/min. Of course, my actual power output would probably be lower. Well, what do you expect from a 18-20 years old engine?

Now that we have the expected injector flow rate, we can calculate the expected fuel pump's fuel rate. I have four injectors so 4 x 230 = 920 cc/min. Multiply this by 0.06 then you'd have the lph value which is 55.2 lph. Get a higher flow rate from your fuel pump just to make sure enough fuel is always delivered. I'd say at least 30% higher so 55.2 * 130% = 72 lph. I read somewhere that stock small port 4A-GE flow rate is 80 lph. So we have a good ballpark number!

The moral of the story is get a fuel pump rated for an engine with at least the same horsepower with your engine. If your engine produces 150 hp, get a fuel pump designated for a 150-170 hp engine.

Other than flow rate, another important thing to consider is fuel pressure capability. You need to get a fuel pump capable of making at least 40 psi of pressure. The fuel pressure regulator will regulate this pressure and keep a constant 35-38 psi at the fuel rail. Not all high flowing fuel pump can make this kind of pressure so make sure you get the correct one. For example, this page on mentioned how usually Mercedes Benz's fuel pump is located outside the tank. This is perfect for my preference. One particular type mentioned there is from Mercedes 280CE, flows 130 lph capable of 200-250 kPa of pressure. Looking at the flow rate alone, you'd think this is the right pump for a 4A-GE. However, 250 kPa equals to only 36 psi. This means that the pump isn't able to build enough pressure at the fuel rail. Another example is a Bosch K-Jetronic pump. This one has almost the same flow rate of 140 lph but capable of making 520 kPa which equals to 75 psi, almost double the required pressure. Hence, this would make the Bosch K-Jetronic a good fuel pump for a 4A-GE application.

My Charmant comes with T50 gearbox as default. Any 4A-GE would bolt on directly to a T50 gearbox. One thing to consider is the location of starter motor and clutch slave cylinder. With the 4A-GE's exhaust port on the left hand side, the clutch slave cylinder would be on the same position with the exhaust pipes. Make sure you provide some way to prevent the hydraulic oil from boiling due to exhaust heat. Unfortunately in my case, the starter motor is positioned differently between the 4A-C and the 4A-GE. 4A-C has the starter motor on left hand side and the 4A-GE on the right hand side, intake side. I need to find a way to reposition the starter motor of the 4A-GE to the left hand side.. I really hope i can use the old sandwich plate from 4A-C or even the starter if need be. See Fig 9.
Fig 9 - Different Starter Motor Position

I found this good guide on relocating the starter motor. It's for 20v but good enough to give you an idea of the work. Below pictures are taken from that website,
Fig 10 - Stock 20v Starter Position
Fig 11 -Hole Cut for New Starter Position
On figure 11, you need to be careful on cutting the hole. Better measure twice and cut once. Make sure the holes align with the bellhousing.

Fig 12 -Elongated Side Cut of Starter Bolt Hole
On figure 12, since the bolt holes are not symmetrical where one side is elongated, a cut is needed where rewelding will be done and bolt hole redrill will be done as shown on Fig 13.
Fig 13 -Reweld and Drill New Bolt Hole
Fig 14 -Excess Plate Cut
Fig 15 -End Result

No modification is needed to fit any stock 4A-GE clutch and flywheel inside a T50 gearbox, with the exception of 4A-GZE. There are three diameter sizes for 4A-GE: 200mm, 212mm and 224mm. 200mm is fitted to pre 1989 4A-GE and i believe 4A-C also has 200mm flywheel. My small port 4A-GE has 212mm and it is the largest diameter that will fit into Charmant's T50 gearbox. The throwout bearing may have to use the stock 4A-C one. Only 4A-GZE uses 224mm flywheel and it would not fit to a Charmant gearbox without any mods.

Since my 4A-GE is intended for FWD setup, there is no spigot/pilot bearing attached to the flywheel. You need a spigot bearing on a RWD setup for the gearbox input shaft to match with. Just get a new spigot bearing for the 4A-C and put in on the 4A-GE flywheel. See Fig 15.
Fig 15 - Spigot Bearing

EFI wiring comes next. Fuel injected cars has many sensors and switches to allow the engine to work properly. This maybe where the biggest headache would come. Just take your time and triple check your work. ECUs are expensive and you don't want to burn ECUs all the time because of some short circuit in your wiring. Since all critical engine sensors, switches and actuators are controlled by the ECU, it is best to start your wiring by checking out the ECU pin out diagram. I have one below for the small port 4A-GE.
Fig 16 - 4A-GE Small Port MAP 16v ECU Pinouts

I am not sure about engine-firewall clearance. If you're fitting a 20v 4A-GE and still keeping the stock distributor, then for sure you need some recess in the firewall for the distributor clearance. As for any 16v 4A-GE, distributor is not an issue since it is positioned differently. With a FWD 16v 4A-GE however, you may find some problem with cooling water outlet hitting the firewall. Hence, some firewall recessing may need to be done.

This is all that i have managed to gather from the internet about 4A-GE swap into Daihatsu Charmant. If you don't find something you need or you know something more that is not here, please inform me. I will update this guide as often as it takes.

*****update Oct 26th 2009*****
Finally got some understanding about the cooling system.. I'll focus on the cooling system for a smallport 4A-GE. It has a remote thermostat housing which, ummm, houses the thermostat for the cooling. First see below pic.. This is a pic i showed to my friend Yohann. He managed to start his smallport 4A-GE in his Charmant. I asked him regarding the cooling system using this pic (click to enlarge)..
As you can see from the pic above, there are four water outlets on a smallport 4A-GE. One just above the fuel pump (number 1), two from pipes going from the front to the back on the sides of the engine block (number 2 and 3) and last one on the back of the block (number 4). If you have the remote thermostat housing, then it's easy. Just see my pic and connect the hoses as stated. Now if you're like me, you don't have the remote thermostat housing, what you need to do is block water outlet number 3 and 4. They're easy to identify. They have smaller diameter compared to the other two. These outlet originally goes to the heater but as it was done by Yohann, they can be blocked. Then all you need to do is connect outlet number 1 and 2 to the radiator! Or.. instead of blocking number 3 and 4, you can also connect the two! Just make sure you don't leave any air when filling up the coolant. Thanks to Yohann for this wonderful guide.


  1. was the original t50 cable or hydraulic Edgar?

  2. the original was hydraulic Paul :)

  3. this is treasure..I learn a lot from your wrote ups! :) thanks..