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Thread: 87 octane engine options for protege

  1. #1
    Registered Member Warburrito's Avatar

    2003 Protege5

    Join Date
    Apr 2016

    87 octane engine options for protege

    My stock engine is fine right now, but I plan on keeping my P5 for a long time into the future. I'd like to start planning a swap or upgrades for the future. I'd like to stick with 87 octane because I'm cheap as hell so what are my options?

    KL swap? This would be my preference and I can't for the life of me recall what kind of fuel I used to run in either of my old Probe GTs. I've read that 87 can be used in a KL03, but I assume I couldn't use it in a ZE with the higher compression. Anyone have actual experience with this because I'm not sure that what I've read is accurate?

    Turbo? Would I be able to run a smaller turbo setup and keep 87 octane fuel?

    Fully bolted N/A DE? What mods would I have to a avoid to keep running 87?

    Anything else I'm forgetting about?

    Last question...Would a meth injection system with just water running constantly allow me to run any of the above setups with 87 octane? Meth would be too expensive...I'm cheap remember.

    I know it's not the most exciting topic but I thought it might make for an interesting discussion.
    03 Protege5 manual (blue) - just bought in April 2015...mods to come
    01 Protege ES manual (tan) - SELLING with over 247k miles and still running -Custom CAI, Mazdapeed lowering springs, Nitto Motivos (best tires ever) on Mazda6 rims w spacers and longer bolts to fit
    93 Ford Probe GT manual (silver) - SOLD with over 200k miles and was still running - Fisk Phantom tires on stock rims, best year for PGT as interior design was way better and car was lighter with only drivers side airbag and no reinforcements in the doors
    94 Ford Probe GT manual (black) - SOLD with over 200k miles and was still running

  2. #2
    Registered Member


    Join Date
    Jan 2015
    Springfield, MO Area
    The difference between a full tank of premium vs regular is around 3 bucks right now. A lot cheaper than water injection.

    I've ran 87 through my ZE and it didn't seem to mind. I still run premium though, the cost difference is minimal.

    A turbo is a bad idea on 87. You want the best fuel you can get to avoid pre-ignition. I believe both the MP3 and MSP require 91.

    The only thing you might have a chance of running pump gas in is the KLDE. That swap is a lot of work and expensive, you could make the same power with a boosted FS on 91.

  3. #3
    Registered Member Corphish's Avatar

    83 RX-7 Gsl, 2000 Mazda Protege LX, 2011 Mazda3 Sport i

    Join Date
    Aug 2016
    Baldwin, WI

    87 octane engine options for protege

    Just saying this seems like a lot of work just to save $3? I'd like to point out that going fast usually burns more fuel than going slow.

    I'd suggest getting a MP3 ecu (right now Ilikebikes is selling one for $100) and then run 91 and get yourself a rewards card with your local gas station. I sometimes get up to 50 cents off each gallon of premium thanks to my rewards!

  4. #4
    Registered Member Warburrito's Avatar

    2003 Protege5

    Join Date
    Apr 2016
    Yeah, you're probably right. Especially If I'm going to drop a few grand on a conversion. I was also reading last night about how someone with a KL03 Probe GT had their mileage drop from 25 or 26 to 22 when using 87 octane. That probably makes up for any cost difference.

    If I decide to go into higher octane levels...Would either the KLZE or turbo DE function well using Countrymark 91 Plus Ethanol Free gas instead of 93 (high test around here). They're about the same price, but I'd love to eliminate the ethanol. If they made ethanol free in 87 octane I'd be all over it right now.
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