Revamping the Rx7

Looking again at the picture, part of the reason the intake pipe packaging looks complicated enough to need to use the stock pipe is because you didn't do the coolant re-route yet. When you do, that thermostat housing and radiator hose will be gone and you'll just need a 90-degree bend.

Maybe do this: Go to Home Depot and get a 180 and a 90 or a 45 in ABS plastic sewer pipe. Take off the filter and install the 180, looping downward. Then attach the 90 or 45 pointing away from the engine. You should be able to stuff the filter in front of the shock tower and could probably even duct cool ait from in front of the radiator to feed it.

The convoluted plumbing won't actually hurt power (I've dyno tested such things, so I'm overruling common sense with experience here), and it will look so stupid and embarrassing that it will motivate you to do the coolant re-route and switch to a simpler crossover pipe.

-D

could i swing the other way and have some short of "short" intake pipe? the reason i went with the stock pipe in the first place was some issue with a hiccup at about 4000 or so if you dont have the little chamber on the tube?

so staring at the engine, could i just turn off the throttle body and go more passenger side ?

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First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

Well, look at it this way - you were going to have to make ducting for the intercooler you WERE going to run, right? So make only the last foot or so of it and cram the filter on the end. Or better yet, put the filter in front of the radiator to begin with.

I catch crap for where my filter is (stuck right above the engine) but air inlet temps are right around ambient. A lot of air moves through the engine bay, sure it gets warmed a little by the radiator but not very much - we're talking large amounts of air moving through in there. Even when coolant temps are HOT the air coming from the pair of tornadoes strapped to the radiator doesn't feel very hot.

But on the other hand, I don't have it stuck less than a fist's width from red-orange glowing headers, either.

---

Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

Quote
Pete
Well, look at it this way - you were going to have to make ducting for the intercooler you WERE going to run, right? So make only the last foot or so of it and cram the filter on the end. Or better yet, put the filter in front of the radiator to begin with.

I catch crap for where my filter is (stuck right above the engine) but air inlet temps are right around ambient. A lot of air moves through the engine bay, sure it gets warmed a little by the radiator but not very much - we're talking large amounts of air moving through in there. Even when coolant temps are HOT the air coming from the pair of tornadoes strapped to the radiator doesn't feel very hot.

But on the other hand, I don't have it stuck less than a fist's width from red-orange glowing headers, either.

You're on to sumpin there. many years ago was reading what both Mocal and Setrab where saying about placing oil coolers. They said the air temp goes up maybe 4 degees C, it's the sheer volume that carries the heat away.
The big deal to make it work is letting air OUT so it basically doesn't "fill up" the engine compartmant and divert around around and over and under the big ass hole in the front...

Alex, youse gotta do something...

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Quote
Gravity Fed
could i swing the other way and have some short of "short" intake pipe? the reason i went with the stock pipe in the first place was some issue with a hiccup at about 4000 or so if you dont have the little chamber on the tube?

so staring at the engine, could i just turn off the throttle body and go more passenger side ?

Is this a huccup you've had, or one you've read about?

What engine management are you running?

If there is a correlation between that resonator and a stumble, the only reason I can imagine would be some resonance that screws with the airflow meter. Since you don't have the airflow meter I assume you don't have the stock management, so I assume none of this applies to you. Generally those resonators are purely for sound and have no impact on performance.

There does tend to be some benefit to having a little bit of length on the intake tube, so I wouldn't just stick the filter on the throttle body (though that would still be better than what you have now). The inertia of the air in that tube can help improve volumetric efficiency. The advice to make your cold-side intercooler pipe now and use it as an intake is a pretty good plan.

-Dave

right now, there is no intercooler. the turbo plan was scraped a while ago.

ill figure something out. lots of crap attach to the stock part near the throttle body, maybe i can force something. but for now, the goal is to just start.

---

First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

I'm still thinking you should just stick it out of the hood.

Quote
Gravity Fed
right now, there is no intercooler. the turbo plan was scraped a while ago.

ill figure something out. lots of crap attach to the stock part near the throttle body, maybe i can force something. but for now, the goal is to just start.

You don't really need any of that crap that attaches before the throttle body. Idle air bypass? ditch it. There's an idle adjusting screw, just crank up the idle high enough that it never stalls and eliminate all the complexity. What the hell else goes there? I can't even remember...

-D

the biggest was the pulse width idle thingy. so i can just ditch it? seems like all the miata folk running megasquirt are insistent that it stays. cause i hate silly attachments. need to figure out block off stuffs to remove it.

---

First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

Quote
Gravity Fed
so i can just ditch it?

I ran my '86 F150 for 3 years without an IAC, just set the cold idle to 800rpm
as the "base idle setting", worked fine...

---

SteveL
This is the point in the killing spree when you really should turn the gun on yourself

The Lego didn't have a functioning iac. I just had the guts of it still plugged in and zip tied to the intake just so I wouldn't get a check engine light.

---

"Rally racing makes a heroin addiction look like a vague craving for something salty"

Quote
Gravity Fed
the biggest was the pulse width idle thingy. so i can just ditch it? seems like all the miata folk running megasquirt are insistent that it stays. cause i hate silly attachments. need to figure out block off stuffs to remove it.

Federal EPA mandates idle is dead steady at XXX rpm so these idle controllers are '"step up the idle" thangs for when say the AC is switched on, or AC and the electric fan for the rad is running or when the AC, the high beams the rad fan the blower kmotor and PS is held hard against the stops---idle will remain constant..
Federal EPA is all about new car sales....

You a new car?
Set the idle call it good.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Neither of my cars have it.

I manually adjust the idle speed in the RX-7 by turning the fans on. Cold idle is ~1000rpm, hot idle is ~1600-1700, turn the fans on and it's ~1300...

---

Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

We took the idle bypass framus off the bottom of the throttle body and filled the passages with JB weld.



And we removed the other idle control doodad on the plenum and replaced it with something flat with four holes in it. (this makes it much easier to service the injectors)



After you do this, set the idle so it will run in whatever worse case scenario you're going to see. Cold engine and headlights or something like that.

Our engine won't idle for the first few minutes of cold start, but we have the intake cam advanced a tooth, which is great for midrange torque (on a turbo car at least), but hurts idle.


While you have the JB weld out, goober up the throttle body screws. Cheap insurance against them breaking off. Apparently this is a common thing on high-revving Miatas. Very common on race cars. Never happens on street cars. I'd never heard of it until we sucked a screw into our engine after 17 or 18 endurance races. Then everyone I told about it said "oh yea, Miatas all do that. That's common knowledge!"



-Dave

some updates!

vast majority of wiring is done! headlights, taillights, brakes, etc working. little more detail work left with chassis wiring. Gauge panel is done, ecu wiring is done. Trying to work to get the car started. Thinking i have a setting wrong with the Megasquirt causing spark to be 180 out.

---

First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023