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  • SR20DET Conversion by Omni

    by Omni

    Once completed your front end should look something like this:
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    Since I have a bit of time on my hands I thought I would get around to writing up a more detailed how to on the sr20det engine conversion. A lot of the information you are going to read is probably already contained in fireballís sr20det conversion that was written up way back in 2001. I have got to say that, when I first bought my Exa in 2002, I was going to go ca18det but after reading the article written by Fireball I decided to go sr20 instead. The reasonís behind this for me was to be different and have a 1 off original car that no one else has, for other people considering this conversion, my advice to you is be dedicated, read through both articles, and know that you are doing something that not many other people have done before you, so it may be a little bit harder to achieve a result. But if you do I hope that it is all that you want it to be and or more.

    Firstly before you start off the conversion, do your research into all the different types of sr20det motors that are available. Nothing is impossible to achieve, it all depends on what you are willing to do to achieve it, or how much youíre willing to pay someone to do it for you. For this conversion, I have used an east-west mounted motor that came out of a Sunny Pulsar Gti-R. I have been told that you could use rwd motors from say an s15 Silvia, however there is a lot more preparation needed to get the motor into a state where it can be used in a fwd car, by this I mean you have to strip back the motor back to bare block and dress it with all fwd parts. If you want more information on this ask an engine builder, who will probably say that, your nuts in the first place for considering it.

    Depending on the motor you decide to go with, and in what state your buying it in, that is front cut, just motor or motor, loom and ecu, expect to pay anywhere from $1500-$4000. Shop around on this as you can save a lot of money. Places to look can include interstate, Japanese wreckers that donít use the net and privately. Also when you buy a motor from a wrecker, try to get some sort of warranty on it. Most will have a Ďstart upí warranty, which basically means that they will start the motor for you and your motor will be covered under warranty from this time. Also consider doing a compression test on the motor prior to purchase. Itís better to check the motor before you have it, rather then finding out you have a dud after you have bought it.

    Well, mechanically speaking, the first thing you need to do is obviously remove the ca18de or ca16de motor that currently resides inside your engine bay. Be gentle as youíre ripping this baby out of its home, and if youíre lucky you might be able to sell it off to someone else, or keep her for later on if you want to swap it back in (However this may be a little hard if you have modified the chassis or engine bay in anyway). All you need to take out is the motor itself, the gearbox and associated wiring that goes with the 2. Leave all body electrics in place as you will need these for the other parts of the car i.e. lights, wipers, washers. You can do away with the hydraulic clutch setup (ca18de only), as well as the drive shafts as either will be useless for this conversion.

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    Ok thatís the easy part done now. What you should be looking at now is a bare engine bay like the picture above. From this point I would strongly recommend that you seek the help of a trained, qualified, and slightly crazy mechanic that CAN weld in both TIG and MIG. The reason for this is that the person that undertakes the engine conversion will have to weld the new engine mounts up for you, and may have to reposition the chassis side mounts in the engine bay. However if you are somewhat mechanically minded and think you can do this conversion, then by all means give it a go, But donít complain to me if it goes all wrong, as like I stated earlier its hasnít been done all that many times so this should be used as only a general guide and not a complete how to write up.

    On the positioning of the actual motor, in my case the motor had to sit a little bit more forward. The reason being that the intake phlenum is particularly large on the Gti-R motor, and you also have to take into account that the motor will naturally rock back and forward under acceleration. Also on the positioning of the motor, you will notice that with the standard suspension, the new motor will only clear the floor by about 100mm after the conversion is completed. The reason for this is that the sr20 motor is about 20kg heavier then the ca18 motor, and that the physical size of the motor is also longer, because the turbo motor has a larger sump to compensate for the larger oil pump needed. To fix this get harder suspension or adjustable suspension for your new ride after the conversion is complete.

    If you have decided to do the conversion on your own then this is how the engine mounts should look like when then are completed. I did not do the mount myself; they were made up by a mechanic. From what he told me, and from what I saw, the standard sr20de mounts can be used, however they had to be cut back and welded onto the ca18de mounts so that you get a hybrid type mount. The driverís side mount on the motor is just a standard sr20de mount; however the chassis side had to be modified to suit the mount. The gearbox mount is the bottom half of a sr20de mount that has been cut and welded onto the ca18de round mount. Note that the chassis side of the engine mount have also been moved slightly forward and re-enforced, to suit the motor as well as the extra power.

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    The above 2 pictures are views of the engine mounts of the drivers side mount.

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    Above are the 2 pictures of the gearbox mount.

    The dog bone mount at the front of the motor also needs to be repositioned on the radiator support to line it up with the motor. The rear engine mount needs to be welded into your cross member, which will line up with the transfer case (gearbox). Although that this sounds very easy, this is the hardest part of the process and will therefore take the longest time to complete. I must stress that when doing this the first time, do it right because you donít want to damage your motor or have any headaches later on. Also make sure you re-enforce the new mounts on the chassis side because you donít want them to be ripped out from the extra torque that highly tuned sr20det motor can make. Another thing that you may want to consider if you have the funds, are urethane mounts. This should stiffen up the engine mounts, which means less movement of the engine (but more vibration throughout the car). Another product I have been told of but never tried is an engine dampener. Refer to the web for further information on this.

    Drive-train

    Firstly in terms of the drive train you will not need the standard ca18de gearbox and all associated parts. By this I mean that the gearbox will not fit up to the sr20det motor. Also the slave cylinder will have to be removed and in its place a cable clutch will be used to engage the clutch. This stage should be started when the engine bay is empty as it will give you some room to move around, and also allows you to dress the motor while it is out of the car instead of when it is in.

    The first step involved with fitting up the drive train and making it work is to source all the parts that you will need. For this conversion you will need:

    -standard sr20de gearbox
    -clutch cable
    -bracket that holds the clutch cable to the firewall
    -standard sr20de flywheel
    -new heavy duty clutch
    -custom driveshaft (maybe)

    Now that you have all the required parts the first step would be to remove the slave cylinder from the firewall. Also from memory check behind the clutch pedal as there is a line that needs to be removed from there as well. (Your gearbox should be already out with the motor).

    If your new sr20det motor is on an engine hoist or on the ground etc, it is now the best time to do a clutch change on it. In order to do this you will first have to change the flywheel as the DET flywheel is too large to fit into a fwd gearbox. You can either get a standard sr20de flywheel, from a SSS pulsar, and bolt it up to the motor, or you can buy yourself a lightened flywheel such as the one from Fidenza. The advantage this flywheel has over standard is that it is a lot lighter, by about 5kg from memory, which means that down low in the rev range you will feel a lot more torque, however the trade off is that up top in the revs, the torque dies off a little. The reason for this being inertia, and if you have some understanding of physics you will understand what I mean. Anyways back to the point, when bolting up your flywheel go buy NEW flywheel bolts. They donít cost too much, and Nissan should have them in stock.

    Now on to the clutch. This issue will have a lot of people arguing over what I am about to write, however this is my own personal opinion and if you have read this far you must be interested in what I have to say. The clutch should be matched up to what you plan to use the car for. By this I mean that if you plan to use the car as an everyday driver, then buy something that will be kind to your gearbox and your left leg. If you are planning on using your car as a track star or weekend warrior (which was my plan) then get a heavy duty clutch that will keep on gripping, but will probably do your gearbox in prematurely. For the people wanting an everyday driver clutch, look for a heavy duty organic clutch. RPM make a decent clutch for this application, and I have been told by the seller that they can withstand up to 300kw at the motor. These clutches grip extremely well and are good in city traffic where you will have to stop/start a lot. In terms of feel, the clutch doesnít feel that much different to a standard factory clutch at all, and useability/drivablity is quite good.

    On the other hand for the weekend warrior or track star you will need something much more beefier. Something that will not give up on you when youíre near redline, on the burnout before your quarter-mile run. For this application you canít go past a brass button clutch or ceramic clutch depending on who you speak to. They are both the same thing just different people call it different names. These clutches are said to be able to handle upwards of 400kw, however they are very hard on the gearbox because of the higher clamping pressure which Ďshocksí the gearbox when it is engaged. In terms of feel of them they are hard to push in, because they have an up-rated pressure plate, and if you drive too much on 1, prepared to look lopsided cause your left calf/thigh muscles will look like a professional footballerís leg.

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    On the left is the brass button clutch that I have fitted up to the Exa. On the right is an example of a heavy duty organic clutch. Apart from the design of the clutch, the other main difference is the material that the clutch is made out of.

    Once the flywheel and clutch are bolted up, its time to bolt up the gearbox to the motor. This is probably the easiest job you will have to do in terms of the drive train. If you follow the lip of your gearbox around, you should notice 2 small metal dowels that extend out of the bell housing. These dowels are aligning tools which are used to line the gearbox up to the motor. Line these dowels up to the female ends on the motor and bolt the box up. Of the 8 or so bolt holes on the bell-housing only 5 line up to bolt holes on the DET motor. Do not worry about this, as it doesnít play that big a role in the whole scheme of things. Just make sure you tighten up those 5 bolts and your now set.

    For the drive shafts this will be different for everyone. The reason I say this is because it all depends on how the motor is positioned in the engine bay in the first place. If the new motor is close to where the original ca18de motor did sit, then you should be able to use standard drive shafts out of any normally aspirated sr20de fwd car. The passenger side drive shaft should be a single piece, while the driverís side is a 2 piece drive shaft. This is a best case scenario, however if you are in the same boat as me and nothing goes to plan, then you will have to get custom drive shafts made up. Speak to a professional about this one, as they do know what they are talking about and should be able to custom fit or even make a set of drive shafts up for you.

    For your speedo sensor, you can use the standard Exa speedo cable. The cable will slide into the speedo sender on the gearbox, and tighten to give you an Ďaccurateí reading. Having said this, the speedo may need to be recalibrated as the sender is different and not meant to suit the Exa gauges, but I never had any problems with this when it was fitted up.

    The shift selectors also need to be modified to match up to where the gearbox sits. This needs to be done after the motor and gearbox is fitted up to the car. I had to get my selectors extended out by about 20mm to reach the new box. The fittings are exactly the same and should bolt up without any hassles.

    The bracket that mounts up to the firewall is a simple metal plate that allows the clutch cable to pass through it in its centre and bolts up to the firewall. The purpose of this bracket is to reinforce the hole that the clutch cable passes through on the firewall as well as stabilizing it. The bracket can be taken from an n13 pulsar that uses a standard clutch cable. The clutch cable on the other hand can be taken from an n14 pulsar. The standard clutch cable that I used came from an n14 pulsar, but it was short buy about 2-3 inches. I had the cable extended out by using a joining nut and a threaded piece of metal.

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    Brakes

    In terms of braking, I strongly recommend that you upgrade the front and if you have drums at the rear changing them to discs. At the end of the day it doesnít matter if you have 200kw at the front wheels if you canít stop. For this reason invest in a set of AD22VF calipers and or hubs. These brake calipers come from the n15 SSS, Gti-r, and nx-r. They are a relatively cheap upgrade and can be performed after the engine conversion. Instead of just buying the calipers and changing them over (which I have been told works), you may want to consider buying the entire hub instead. The reason being that your Exaís wheel bearings are probably on the verge of collapsing as they would be 15 years old and probably driven on for around 200000+ kms.

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    The left hub/brake setup is from the Exa. The right hand side is the AD22VF setup. Notice the larger rotor surface area, as well as the larger caliper. Also they still remain the same stud pattern.

    For the rear if you have drum brakes as I did, change them over to discs. Although they donít do all too much in the whole braking combination, you still want to have the maximum braking power that you can afford to get. For the rear brake change you will need to get the:

    -2 rear hubs
    -handbrake cable
    -calipers and rotors

    The change over process for both is covered in more detail on the www.exaclub.com website under the modifications section.

    Wiring

    The wiring on the motor should be very simple IF you bought the motor with the original harness still attached. If thatís the case then it should be a matter of connecting it to the power of your car, and connecting up the sensors that are yet to be connected, i.e. coolant temperature, and oxygen sensor. You may need to refer this matter to a certified auto electrician as the sensors are not calibrated to the ECU that you bought.

    If however you are planning to do further modifications in the future, and want an ECU that will accommodate all your future modifications then you may want to consider an aftermarket ECU. There are a range of different units on the market and each has their own positive and negatives. For what I was planning on doing with my car, I had to go aftermarket. I chose an ECU that was relatively cheap to purchase and install. However there are hidden costs to consider when buying a computer that I wasnít aware of until recently. The initial costs of an ECU will vary depending on what you have chosen and paid for. The Ďrealí money that is spent on the computer comes in at the tuning stage. Dyno tuning is an expensive exercise that will end up costing you. My advice to you is that you go see someone that has a name in the industry, ask a lot of questions, and get it done right the first time. You could always go the backyard mechanicís route and try to get the cheapest but with tuning you get what you pay for. Another thought you may want to consider is that if your tuning is done dodgy, you may blow up your motor, which will cost a lot more to fix.

    Exhaust

    The exhaust is an all important modification that will need to be carried out with the conversion. On a DET motor the standard Exa exhaust wonít cut it. You will need to go bigger. I would recommend either 2 Ĺ - 3 inch exhaust. Not a lot to write on this matter except replace your old exhaust system with a new one. With the unit that I ran with, I got a custom 3 inch down pipe (dump pipe) made up which ran to a flexi, then connected straight to the catalytic converter. From there the exhaust went to a cannon style muffler.

    Other modifications

    Above is the basic modifications that should get your car up and running. Some of the other modifications that you may wish to consider are:

    - Relocating the battery into the boot area.
    - Removing the space saver tyre from the car (the battery fills this space up)
    - Get an engineers certificate
    - Getting even better, larger front brakes
    - Fitting a high pressure aftermarket external fuel pump.
    - Fitting a surge tank.
    - Fitting a fuel pressure regulator.
    - Get urethane engine mounts made up.
    - Get an aftermarket radiator made up
    - Fit larger thermo fans to the radiator
    - Get a front mount intercooler fitted to the car
    - Fit aftermarket gauges such as a boost gauge and air/fuel ratio
    - Fit a turbo timer
    - Run a boost controller
    - Fit a good quality B.O.V
    - Fit an aftermarket POD filter
    - Fit an oil catch can
    - Heat shield everything that runs hot or needs to stay cold
    - Upgrade the turbo
    - Use fully synthetic oil, and good quality coolant at all times
    - Rebuild your motor to handle bigger power reliably
    - Fit a Nitrous oxide kit
    - Get aftermarket coil over suspension
    - Fit larger wheels (18 inches with rolled guards) with wider tyres (215 or wider)
    - Respray your car black with a gold pearl J
    - Fit a body kit

    Costing

    Car- $4000
    Motor- $2000
    Fitting motor- $2500
    Larger turbo + manifold to suit- $1700
    Exhaust system- $850
    Front mount + piping- $1500
    Front brake upgrade- $250
    Rear disc brake upgrade- $200
    Microtech computer + fitting- $1500
    External Fuel pump + surge tank- $500
    Turbo timer- $200
    Boost gauge- $140
    Duel stage boost controller- $200
    Thermo fans + controller- $320
    BOV- $130
    Pod filter- $100
    Gearbox- $500
    Brass Button Clutch- $490
    Extending gear selectors out- $120
    Flywheel- $100
    Dyno tuning- $150 (cleaning up fuel maps)
    Towing the car around- $700
    Other stuff that Ive lost count of i.e. spark plugs, oil, gear oil, coolant etc- $500
    Time put in myself - 600+ hours (Over the time of around 2 years)
    Running around getting parts- ??
    Nights lost sleeping - TOO MANY!

    Thatís just off the top of my head. The time it took to get the conversion done is ages. It all comes down to how much money you have to spend on the car, or your mechanical knowledge and the time you want to spend fixing up your car. You can pay someone the big dollars to do this conversion for you, start to finish and it would probably cost around $10,000 in labour + parts. This is a rough estimate, as most mechanics will most likely just laugh at you for even thinking about doing such a conversion. Time it should take a professional, no longer then 3 months tops. And thatís not working on your car full time either.

    For myself, my Exa was a labour of love. I originally purchased the car on December 31st 2002, and the motor was out of the car by early Feb 2003. My car had been off the road for around 18 months, and while I didnít do the major job of fitting the motor, I have pretty much worked on everything else mechanically. On May 19th 2005 my car was sold to EdZ^eXa, a fellow member of the exaclub.com forums. His building a website at http://users.ncable.net.au/~edenb/srexa/ which is dedicated to this project.
    Comments 3 Comments
    1. TOOQIKK's Avatar
      and they said you couldnt put a gtir motor in a exa! very nice job and very nice car!! and very nice write up!
    1. TOOQIKK's Avatar
      could throw in a lightened flywheel too! while you had it apart!
    1. PLZ818's Avatar
      I will be going one step further