Frankenstein 4g93/94

Discussion in 'CE Lancers and Mirages' started by Johnzy, Aug 29, 2019.

  1. Johnzy

    Johnzy Member

    I'm hoping to speak to someone that has done this convertion. I'm trying to find out if the compression ratio changes and what kind of problems I will run into.

    I would like to swap the 93 head with the manifolds and the cam on to the 94 block. I have read thought the engine convertion thread and don't find much. Looks like I will need the power steering pump and braket from the 94 as well as the sump.

    I can get a motor from the U Pull It for around $200

  2. donki

    donki Administrator Forum Administrator

    Compression ratio does not change, that's a pistone bore and stroke ratio, not cyl volume
    Johnzy likes this.
  3. Johnzy

    Johnzy Member

    As far as I'm aware compression ratio (in very basic terms) is how many times the combustion chamber volume fits into the total cylinder volume.

    So by increasing the bore and stroke e.g. 1.8L to 2L but not changing the head or combustion chamber then the compression ratio should change but i dont know if it will change enough to have any effect.
  4. SDate42

    SDate42 Active Member Lifetime Premium Member

    93 head on a 94 block is do able. You will need to bring all the sensors to suit your Ecu. Keep throttle body and tps and iacv matching to ecu.

    Also replace head gasket, timing belt, water pump, crank,+cam seals, idler pulley, rocker cover gasket, coolant, oil.

    Are you currently 4g94 motor or 4g93 motor?

    Comp ratio does not change. Dish size in the head is the same.
    Johnzy likes this.
  5. Johnzy

    Johnzy Member

    SDate42 I have the 4g93.

    Im very surprised that the combustion chamber is the same because the bore diameter is slightly bigger.

    If the diameter of the bore and the stroke change but the combustion chamber stays the same then compression ratio changes.

    Maybe it's just no enough to make a big difference
  6. donki

    donki Administrator Forum Administrator

    Yes, but you're be measuring in thousandths of a ml of instead of ml - the difference between the head volm is not enough to even bother measuring, as the major changes between the engines is the bottomend. The compression ratio is the same between engines also
  7. SDate42

    SDate42 Active Member Lifetime Premium Member

    Humble opinion if you want the g94 Get a complete 4g94. Swap in the 93 cam and intake manifold. Port the manifold along the way if you can be bothered.

    You’ll have a little less torque down low, but you’ll pick it all up again in the mid to top range. In a CE, you can afford that. In doing this you get the best of both by sacrificing a bit of both. Easiest, simplest, cheapest way to go about it for max gains.

    If you’re going to sink money into the car later, I would stay g93 block and make use of the higher rev-ability. 4g94 will not rev as hard and is “weaker” for boost/power making. These are both due to the longer stroke.

    I get where you’re coming from with the combustion chamber size, but you’re not quite on the money. Deck height is something you haven’t considered. Also note that the increase in bore is 0.5mm. When this is calculated as part of the dish, it equates to sweet *fudge* all. There would be far more change in comp ratio due to how much has been skimmed off the head when you get it squared for fresh installation.

    Also remember that 0.5 larger is also a standard size for oversize pistons to be used on a worn block. When you use oversize pistons, you don’t hear people talking about how the comp ratio has changed or how their 1.8l is now a 1.82L haha.
    Johnzy likes this.
  8. Johnzy

    Johnzy Member

    So the name of the game at the moment is "cheap". I have just bought a house but I still want to do some work on the car and take it to the track. In the future I might turbo it but would build the bottom end if I did.

    Have either of you built one of these motors? Do you have any dyno sheets or time slips ect.
  9. staahnaah

    staahnaah Active Member State Event Organiser

    There would be no need to build the bottom end of a 4g93. Unless your planning for 20+ psi of boost. Stock block turbo 4g93s have been around the low 13s in 1/4 mile times. Thats with 14-16psi.
    There would be a bit more into getting the time to a 12 as the 60 foot mark is about the same time we need to change to 2nd gear.
    Getting a good launch would also be another factor as with any good time.
    Personal best for me is 13.4 with an average 2.3 or 2.4 60ft time. My MPH is good enough for a high 12 but just having a combination of things go right would get that time.
  10. SDate42

    SDate42 Active Member Lifetime Premium Member

    Cheap? Then do as I suggested. 4G94 complete. Bring 93 cam, intake exhaust and sump. Standard g94 ecu. Turn key power and torque increase.

    Donki has a turbo 4g93 mirage. Have a read through the drags time slips thread to back his car up.

    I have a turbo 4g94 CH Lancer. Built 4g69 crank up, head services galore across the 4G9x range and owner many Lancers previously.

    Staahnaah has owned both turbo 93 and 94 mirage for reference too.

    The 93 is “stronger” for making power stock, but if you get forged rods and pistons, why not have the extra displacement of the 2L.
    Johnzy likes this.
  11. staahnaah

    staahnaah Active Member State Event Organiser

    @donki and I have similar set ups the different being turbo size among some other minor things.

    @ARC has a DOHC 4G93 aka C5MA engine.

    All around the mid to low 13s mark.

    Just have a read of some our ride threads if you haven't already. The general consesus is to turbo a 4g93 as 4g94 has 'skinnier' rods.
    Johnzy likes this.
  12. Johnzy

    Johnzy Member

    Thanks for the info but at this time im just interested in the na motor not the turbo motor specs.
  13. staahnaah

    staahnaah Active Member State Event Organiser

    Off the top of my head, the best NA time would be somewhere in the 15s. Without sourcing a 4g92 mivec head there isnt anything really worth doing for NA.

    Even 4g94 block and bits and bobs of 4g93 is a minimal increase. Eventually you will end up having to redo a majority of things for a turbo build.

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