paradigm

Mod Edit: I moved all of the 2010+ discussion about the value of doing this to it's own thread in Tech.

The debate isn't really appropriate here.

If you want to see the debate, click here: https://www.rx8club.com/series-i-tec...thread-245771/


Begin original Post:
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This mod is for those of us in hot climates. People in areas where it gets really cold may want to consider the fact that this may have an effect on warm-up.

Coolant runs through the throttle body to help get everything warmed up, but when the car is warmed up, this means that the intake air must run through a ~180 degree heater before entering the engine. This means lots of heat soak for people in hot climates.

You're not going to notice a huge difference in power with this cheap mod, but you won't get as much heat soak, and for about 5 dollars you can't really complain. :p

Here's a parts list. The brass hose splicers I used could've been a bit smaller on one end (5/16*3/8 as opposed to the 3/8*3/8 I used).

2x..3/8*3/8 barbed brass hose splicers
2x...Hose clamps
1x.....~6" 3/8 inc inner diameter heater hose (I got 10ft for 7 bucks at a local auto parts store)

Instructions are simple. Take off your intake first, or you won't be able to get to the hose on the bottom of the throttle body. Pull the 2 coolant hoses off the throttle body. Splice in your 6" heater hose, clamp it down, and VOILA!!!

shelleys_man_06

Interesting mod. I live in Texas and it's a freakin' sauna here. I might try it. Thanks paradigm.

paradigm

Any time.




I also should've said that instead of the parts I used you can use a single piece of metal pipe with an outer diameter of about 3/8 inch, but as much as I looked I couldn't find any pipe to use, also the pipe wouldn't have the barbed ends like the brass splicers I used have.


As soon as I get my hands on the CANScan software I'll try to get some intake air temp readings, and compare them to a car that doesn't have this done.

bgreene

It's unlikely you'll see any difference reading off the car's data channels. I'm pretty sure that the stock IAT sensor is located on the same unit with the MAF sensor, which is in front of the throttle body.

You'd need to install another sensor somewhere in the upper intake manifold to get a reading downstream from where your mod changes things.

rotarygod

It's not a reading he is trying to affect. This is a mod that I've done to every car I own. the premise is that since the coolant (strange term in this scenario) is running through the throttlebody, it heats up the throttlebody. Since air runs through the throttlebody, it heats up the air. The whole point is to get a little cooler air into the engine. Will you feel it? Maybe, maybe not. But it is essentially a "free" mod.

bgreene

I understand all that, I was responding more to the later part of the post where he talks about logging comparison data on with/without cars to try to quantify the effect of the mod. My only point was that a sensor upstream of the mod point will not produce any data significant to determining what effect is there.


P.S. how much coolant gets spilled in the course of this mod? I'm swapping out my springs/sways this weekend, and I might do this too while I'm in there....

nite crawler

I think what bgreene was refering to was how paradigm said he was gonna take readings from his intake temps and from a stock TB'ed RX8. Bgreene was just saying that he thought the intake temp readings would be readings from before the TB, so if there is a difference in temps, it would NOT be correct data to use in proving the difference this mod made.

Nate

nite crawler

damn, too late

bxb40

I remember I read once about using a similar mod. Some Firebird owners build a second separate cooling circuit using the windshield washer pump, a separate reservoir filled with water and ice, to overcool the TB. They would run this mix at the track, between runs, to cool the TB. Their claim of increase performance was based on colder air being more dense so they would get extra mass in the cylinders. Kinda makes sense but from what I read about the Renesis, even if you remove the air filter power is the same, so extra air is not needed. But it is a free mod :o) I'm in NJ, so it is not for me.

Omicron

Cool idea. Moving this to the DIY forum. :D

09Factor

Since i dont have to work today and i'm bored.. Why the heck not.
it's quite warm In AZ. I'll try this out.

09Factor

I took the TB off and looked on the backside of it. There was a gray ring of crap where the valve meets the TB sides. I'm guessing that it was the lube that Mazda uses for the venturi pivot points. I cleaned the TB w/ carb cleaner. Sorry I didn't take a pic.

Can someone confirm this?

I haven't had a chance to drive the car in the heat yet so I can't say anything about the mod. I'll post thoughts about it later.

ddub

Sorry to bring this back from the dead and all... but I figured I'd give some input from a "colder" area.

I did this mod, first of all a 3/8" barb is a tad "tight" with the stock hose. I didn't use any new coolant hose, I merely pulled the stock hose out of its bracketing, cut it, and have it connected near the alternator. This moved it completely away from the tb, shorter overall, cleaner, etc. The 3/8" by 3/8" brass adapter was NOT easy to fit into the stock hose. I forced it in and it's okay now, but I think 5/16" would be a much better fit. Just my input...

As far as warmup goes, it's completely unchanged. Since the cold start warmup is controlled by the PCM, I didn't expect it to change at all. It still revs up to 2k rpms and all on cold starts until it is warm, so I don't see how this mod becomes an issue in cold climates. Unless I'm missing something? I mean, the coolant is cold on startup anyways, so how does it help warm things up? Maybe I'm missing something, I'm not sure. I know on older cars they use a thermowax system for the cold start, but since ours is PCM controlled I don't see how it makes a difference.

Either way, I've been starting the car up in 20-30º weather without an issue. Cranks and fires immediately, no idle issues, nothing. Just thought I'd let people know this mod isn't a big deal at all. Also thought I'd give my input on the 5/16" adapter possibly being a better fit than 3/8".

Moonrover333

so it doesn't affect the cold startup?

ddub

None that I've noticed. Been starting my car up in 20-30º weather for over a week now, no issues.

Like I said, I don't see how it WOULD effect cold start/warmup since it's PCM controlled for the accelerated warmup. But I might be missing something and someone can correct me if I'm wrong.

samsong

Interesting. TB mod doesn't affect start-up (above). I wonder if the heater is there for another reason.

In airplanes, the carburetors have heaters installed to prevent icing. Could the coolant to the throttle body be acting in the same capacity? Could a cold, humid morning result in icing around the throttle body plate if the TB isn't heated?

I'm speculating here...
thoughts?

ddub

I went through some of my friend's auto-tech books from his school to try and figure out what the purpose might be. So far I'm still really not sure.

One thing one of the books talked about goes along with what you (samsong) said. It said that sometimes coolant running through the TB is a way to melt frost/ice that might have formed along the inside of the throttle body/tb plate(s). But this doesn't really make sense. The coolant is COLD when you start up, just as cold as the frost/ice. So how is this supposed to help melt it or keep it from forming? Doesn't seem logical to me, but maybe I'm wrong.

The book also mentioned that coolant is sometimes used in carburetors and some fuel injection setups to help heat the fuel mixture as it goes into the engine, providing a more efficient burn. I guess I can buy that, though I don't think it matters. However, that only works if the coolant is AFTER the fuel injection on EFI cars. The coolant in our TB is prior to the fuel mixture, so this doesn't mean jack for us.

And that's all I could find. I still want to know why Mazda did this! I can't find a purpose in it, it's confusing me

samsong

Thanks for your thoughts.

Clarify: The carb heaters on the planes are on all the time, though...it's to keep it from icing during normal operation (not just start-up).

I would think the ice would form when the low-pressure around the throttle causes the watervapor to condense (ever watched an airplane at take-off and see "clouds" form on the tops of the wings?). Maybe that condensation could also freeze to a cold TB and build-up during other than WOT operation.

Again...just my speculation.

Schuistheman

You will notice the greatest diffrence from this mod in the summer. Just try and touch the throttle body after you have been driving hard for 20 miuntes or so before and after the mod. The tb goes from scolding to warm in the summer months.

dgrx8

ok guys... i live in miami & i could defenitely benefit from this mod. the only problem is that i'm not the most mechanically inclined person out there. i could defenitely follow a DIY on this but it just seems a little too vague to follow. also, the pictures didn't seem to help me much either... no offense to paradigm at all... actually, i'm glad i came across ur post. could any of u guys help me out a bit on this??

ddub

I'll take some better pics some day for you. For mine, though, I cut the hose to make it shorter and moved it to the other side of the alternator since I saw it pointless to ADD hose and wrap it around the TB.

It's really not complicated, just take my advice earlier in this thread, 3/8" barb is too big for the stock hose that goes into the TB, 5/16" would work MUCH better.

dgrx8

bump

ddub

Oh yah pictures. Okay I took some.

So the pipe/nipples that are left after the rerouting I capped. Don't need to, I just preferred not to have debri or anything get in there in case I ever decide to revert it back to stock.

Pic of the first cap where the hose used to go.



Pic of the second cap where the hose used to come out of. Was kind of hard to see so I added an arrow to guide you



Close up of the barb and where I moved the hoses/made the connection.



And standing back a bit further so you can see everything.








EDIT:
Why wont the img tags work in the DIY section

dgrx8

ur the man dDub... thanks a lot!

dgrx8

ok dDub, I finally got this done... only took about 5 min. the 5/16" barb fit like a glove! my only concern is that i didn't cap the throttle body ends where the hoses were attached. i cut the bottom hose off to avoid having to disconnect my intake. i can always cap the top opening. but, i won't be able to get to the bottom one until i get around to disconnecting the intake for w/e reason. so, i'm wondering if there would be any problem with debris getting in there somehow...
also, i'll let everyone know how this works out for me here in miami temps...