HOW TO: 9G Lancer Hot Water Bypass

Discussion in '8G Lancer - Knowledge Base' started by lordtygr, Nov 1, 2008.

  1. lordtygr

    lordtygr Well-Known Member

    Couldn't post a new topic in the knowledge base. so i figured i'd post here and it would get moved if necessary. Or i can repost it in a different forum later, whichever.

    First, some semi-legal mumbo-jumbo:

    **Disclaimer** Neither I nor LT should be held responsible for any adverse effects this may have on your car. This is simply a suggestion , and you assume all risk of performing this modification.

    That being said, this is probably one of the easiest and cheapest “performance†mods you can do for your car. I recommend this for people living in warmer climates however, if you feel comfortable doing this in a cooler climate, I don’t see how this would hurt. I live in Houston, TX where we’re ‘lucky’ if we get temperatures below freezing over the course of the year. However, when it gets hot… IT GETS HOT.

    Mitsubishi and many other manufacturers, in their infinite wisdom, decided that to help our engines warm up from a cold start, they would run hot coolant through our throttle bodies to warm up the incoming air. That’s fine for the first couple of minutes your car is running but, this is a continuous system. Even after your car is at operating temp (probably between 180-220 degrees) and the temp outside is 101 in the shade. That hot coolant is still flowing thru your throttle body.

    Most people know that as the temperature of the air is increased, it becomes less dense. This reduces power and efficiency. This is the reason we have CAI’s, intercoolers with turbo’s, vented hoods, etc. It’s all about reducing the air temp.

    I have done this mod on my lancer and the 2 vehicles I owned previously with no problems. But honestly this isn’t going to be something your probably gonna feel on your “Butt-Dyno.†Heck, you may only even gain a half HP. IDK. I’ve never seen a Dyno sheet posted of before/after this mod. But for under $10 and maybe a couple of beers, it’s kinda just something to do on your car. I also recommend having a buddy help you, as having an extra pair of hands is always nice (and less coolant lost), and sharing that beer is good too.

    Drip Pan, unless you don’t care if you drip fluids on your grass/driveway. You will lose some fluid!
    Screw driver
    If you have some laying around some 3/8†bolts if not… work fast ;)
    Small Tie Wrap (Zip-Tie)

    Hose Clamps (really shouldn’t need them but, just in case)

    3/8†Barb Splice Coupling (From Lowes or Home Depot)

    Vacuum Hose Caps (From Auto Parts Store, Got mine @ Auto Zone, each pack has 1 of each size so get 2 packs)

    Anti-Freeze (I don’t care if the bottle says safe for all vehicles. The owner’s manual says ethylene glycol, so use ethylene glycol. I also recommend getting the pre-mixed. It’s just easier.)

    1. Remove Intake Hose between TB and Air Box.

    2. Lol, we didn’t get to this till later, but you should cover the throttle with something. We used a shop rag. Don’t want coolant getting in there.

    3. Use your pliers to loosen the OEM hose clamp and gently remove the hose from the nipple. Put a 3/8†bolt in the end of the hose temporarily to keep from leaking fluid all over the place. If you damage the OEM clamp, this is what the extras are for.

    4. Put one of the 3/8†caps on the end of your barb splice. Then repeat step 3 for the second hose. This time inserting the capped splice instead of the bolt.

    5. Put Caps on the nipples on the throttle body. This is to keep dirt and such from getting in there so if for some reason you need to put things back to original.

    6. Remove the cap from the splice and put your finger over the end. Also, remove the bolt from the first hose and also put a finger over the end. This is just to minimize the amount of coolant lost and to keep from making a big mess.

    7. Put the open end of the splice into the first hose.

    8. Use your pliers again the gently move the hose clamps back into position at the ends of the hoses over the splice. Wipe everything down and check for leakage.

    9. Tie wrap the first hose to a solid point. To keep it from flopping around too much.

    10. Re-install the intake hose (take whatever you used to cover the throttle out, lol)

    11. Add Coolant if necessary. The marks on the reservoir are for when the car is cool. When the car is hot/running there will be less coolant in the reservoir.

    12. Clear under the hood of all tools/materials and start the car. Keep an eye on your splice and watch for leaks. If the car comes up to temp with no leaks, take it for a short spin. Keep checking the splice.

    13. After the car has run for a while with no problems shut it down and let it cool. Check your coolant level again. Add if necessary.

    **Note: You WILL spill some coolant. So for at least a few days after you do this, you will smell it when your driving. Don’t be alarmed. Just keep an eye on your splice and coolant level. If you keep needing to add coolant, something is wrong. Figure it out and fix it, or put things back the way you found them.
  2. SoflaGTS

    SoflaGTS Well-Known Member

    did u notice a difference
    because i might give this a shot to go along with my injen
  3. lordtygr

    lordtygr Well-Known Member

    but perhaps when used in conjunction with an Intake, you might notice more
  4. Prophet

    Prophet Well-Known Member

    Moved... thanks for the How To... you should be able to post in this thread just let me know if you can't and in the future just post like how you did and request from a mod or admin to move to the knowledge base.
  5. lordtygr

    lordtygr Well-Known Member

    10-4 good buddy.
  6. skullpr

    skullpr Well-Known Member

    nice wright up man....i could use this here in PR...its always hot as a MF, lol
  7. Dabrits

    Dabrits Well-Known Member


    This mod is generally useful in conjunction with a CAI. I think I disagree with you when you said that you might gain half a HP. This mod has been done quite a bit on a B14 and supposedly saw pretty substantial gains. For being as cheap of a mod as it is, I don't see a whole lot of reason why not to have this done to your car for atleast part of the year. It is easy enough to change according to the season.

    Here is a bit on info I pulled from an SR20 forum (which pulls some of it's info from other places):

    "Our cars have Coolant running through the Throttle Body, thus heating up the Throttle Body. When installing a Cold Air Intake (CAI), you are bringing cold air into the engine, thus giving the car more power.

    With the throttle body being heated, that cold air can warm up, thus not getting the best results possible out of a CAI. Bypassing the coolant passage way can help the air keep colder. mentions this as an important mod to consider when you install a Cold Air Intake. Source
    Throttle body heater bypass

    Cold air induction kits work pretty well but you need to do your homework first. A lot of cars have throttle body heaters, whereby coolant from the engine is circulated around the throttle body casing. The idea is to warm up the throttle body to prevent icing in cold weather. The problem is that these systems are hard-wired and don't take account of external air temperature, so even in the heat of summer, hot coolant is routed around the throttle body. This is a problem for CAI kits because you've gone to all the trouble of putting a nice kit in to suck cooler air into the engine, but at the final hurdle it runs through a 75°C throttle body which heats it up again, negating the whole point of the CAI kit in the first place. The solution to this is a throttle body heater bypass, which essentially involves pulling the coolant hoses off either side of the throttle body and patching them together with a length of copper pipe and two hose clamps. When you do this, the throttle body stays at ambient temperature and the CAI kit gets a chance to do its job. The only downside to this is if you live in a cold, humid climate, you might suffer from icing in the winter. But hey - if you do, reconnect the coolant hoses for the winter...
    The coolant was designed to run through the throttle body for a reason, to keep the butterfly from freezing shut or open and to keep the coolant temperatures lower. If you live in a cold area, I would avoid doing this. I personally will go back to stock in the winter.

    I will honestly say it is not too great of an idea to go this route with a Daily Driver car. A better choice is to go with the ThermoBlok Spacer Kit. They have a Intake Manifold/TB spacer. This will give you bigger power gains and a piece of mind

    This is a fairly simple mod that shouldn't take longer then an hour to install

    Now I noticed that my water temperature was higher then normal. So that means that the intake does actually cool the water pretty well. I think Redline Water Wetter might do the trick at keeping the water temperatures down though.

    Onto some numbers, now these are not 100% accurate and are not dyno proven. These numbers are from ScanGauge II, and are BHP numbers.

    Base Number: 159 BHP (15% Drivetrain Loss 138 WHP) with 82*F Intake Air Temperature
    After Number 164 BHP (15% Drivetrain Loss 142 WHP)with 83*F Intake Air Temperature"

    Now I know that there could be a myriad of different factors that could play into a 4 WHP gain, but typically if you were to determine your HP, it can go down as your car gets progressively hotter. But even with a margin of error, +- 4 WHP is a pretty big margin either way. Anyway, here is the link to the actual How To from the SR20 forum, ... ypass.html

  8. lordtygr

    lordtygr Well-Known Member

    nice! thanks for the additional info!
  9. Dabrits

    Dabrits Well-Known Member

    Ya no problem. I did this mod to my SR20DE. Works well so far, and I haven't even seen my temps rise at all because of it. One thing to note is that a heated throttle body does reduce emissions. So this may not be the best mod for all of you CA people, although, with newer cars, let's hope you don't have emission problems yet.
  10. jacob1bc

    jacob1bc Well-Known Member

    well if you have a PZEV + header you won't pass smog. like me. i would also guess the timing box wouldn't help
  11. Dabrits

    Dabrits Well-Known Member

    But then again, you could always make friends with the techs at the auto hobby shop and they could "inspect" your car for you and you'll pass every time. I only met one guy at MAFB AHS and he didn't seem the kind to "help" inspect your car. We got some great guys here at Columbus.
  12. Dabrits

    Dabrits Well-Known Member

    One thing that I neglected to mention, is that you could always spend a few bucks more and buy a brass valve and run a double/triple bypass and one simple flip of the valve and you have coolant running through the throttle body again. It would work well for those people who live in regions with seasons.