Welcome Guest [Log In] [Register]
Posted ImageWelcome to the all new Geo Metro Forum. We hope you enjoy your visit.

You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are features you can't use and images you can't see. Registration is simple, fast, and completely free. If you're already a member please log in to your account to access all of our features:

Join our community!




Username:   Password:
Add Reply
G10 intake manifold porting.; For MPG but, all info is welcome.
Topic Started: Feb 10 2018, 09:34 PM (200 Views)
Turbo Dan-O
Member Avatar
Obsessive Car Detailer

I picked up this non-EGR intake a few weeks ago and I'm about to start working on it. I haven't messed with any G10 intakes yet. I want to do what's best for gas mileage so, I was planning on just cleaning up the casting marks and giving everything an 80 grit finish. Now that I can really look over it, I see that it has a NASTY looking turn(that's cast into it) under the throttle body. The hot rodder in me wants to grind that out and make a smoother transition. Surly that couldn't hurt anything right? I don't know. Suzuki made it that way for a reason. I'm not looking to go backwards in MPG.... :scared

Posted Image
Posted Image
Posted Image


The last pic was taken from the middle intake port looking towards the throttle body opening. That's a brutal turn for the A/F mix to make. That being said, I'm running a 3.52 transmission and 13" tires so, my RPMs are VERY low most of the time so, efficient low end torque is needed. I realize we are in the "splitting hairs" department here but, I'd like some input before I take the grinder to it. :popcorn
Edited by Turbo Dan-O, Feb 10 2018, 10:01 PM.
Online Profile Quote Post Goto Top
 
compnut21
Member Avatar
Geo Enthusiast
[ *  * ]
My first thoughts for low end torque would be to increase the plenum size however you can, smoothing out the flow paths wherever possible. Definitely leave it somewhat rough for fuel atomization, blending in those horrible seam lines. I'm somewhat curious how efficient that extra hanging length of the runner on the throttle body side is or isn't. Gonna be watching this thread for sure :D
Offline Profile Quote Post Goto Top
 
Azhule
Elite Member
[ *  *  *  *  * ]
I'm a fan of thinking "outside the box" when it comes to "Porting"

Posted Image
Offline Profile Quote Post Goto Top
 
Turbo Dan-O
Member Avatar
Obsessive Car Detailer

compnut21
Feb 10 2018, 10:07 PM
My first thoughts for low end torque would be to increase the plenum size however you can, smoothing out the flow paths wherever possible. Definitely leave it somewhat rough for fuel atomization, blending in those horrible seam lines. I'm somewhat curious how efficient that extra hanging length of the runner on the throttle body side is or isn't. Gonna be watching this thread for sure :D
Thank's for the reply. I don't think increased plenum volume=more low end torque. I have always been told the opposite but, I could be wrong. This is where I'm hung up. If I grind that "extra hanging length" out, plenum volume will increase. I'm in. I wan't to do it but, I don't want to go in the wrong direction. :hmm
Edited by Turbo Dan-O, Feb 11 2018, 12:23 AM.
Online Profile Quote Post Goto Top
 
freegeo
Member Avatar


Increasing intake runner size won't help your low end torque or mpg.
Edited by freegeo, Feb 11 2018, 01:55 AM.
Online Profile Quote Post Goto Top
 
CaptainMetro
Member Avatar


Try 1" NPT pipe thread, it works great for turbulence.
Offline Profile Quote Post Goto Top
 
compnut21
Member Avatar
Geo Enthusiast
[ *  * ]
Turbo Dan-O
Feb 11 2018, 12:03 AM
compnut21
Feb 10 2018, 10:07 PM
My first thoughts for low end torque would be to increase the plenum size however you can, smoothing out the flow paths wherever possible. Definitely leave it somewhat rough for fuel atomization, blending in those horrible seam lines. I'm somewhat curious how efficient that extra hanging length of the runner on the throttle body side is or isn't. Gonna be watching this thread for sure :D
Thank's for the reply. I don't think increased plenum volume=more low end torque. I have always been told the opposite but, I could be wrong. This is where I'm hung up. If I grind that "extra hanging length" out, plenum volume will increase. I'm in. I wan't to do it but, I don't want to go in the wrong direction. :hmm

The increased plenum size generally will act like a capacitor does, smoothing out the air pulses for an overall broader increase in efficiency. What you end up sacrificing though is a small amount of throttle response as the inertial mass of the air is also going to be increased. Although without drastic modifications such as cutting up manifold to deepen the bowl, whatever volume gained here is likely to be insignificant anyways. Maintaining smooth flow paths is going to be where we're likely to see the most improvement with these manifolds, cutting down and blending in from the TB into the plenum seems like a good starting point. A bit of port matching and smoothing out that nasty seam line are also recommended of course
Offline Profile Quote Post Goto Top
 
sser2
sser2

If your goal is fuel economy, you need a manifold with EGR passage.

Porting is to squeeze power at top rpm at the expense of optimal performance at lower rpm.
Online Profile Quote Post Goto Top
 
t3ragtop
Member Avatar
Turbo3 and Twincam Tweaker

the tbi manifolds need to have that torturous floor at the bottom of their tiny plenum. the spritz from the injector puddles under the throttle body where the heated manifold sort of boils the raw fuel into vapor.

there's not really a lot you can do with that except to clean up the parting lines and casting spikes (blobs) in the runners. i use an 80 grit flap sander on a spring shaft. leave the sanding swirl on the walls as air perturbation actually helps to hold fuel droplets up in the air stream. ;)

port matching and a little work on the embossed steel manifold gasket aids air flow by removing the step at that point.

basically, those manifolds aren't ever going to tweak up like the twincam or turbo3 manifolds that use more or less direct injection at the intake ports but cleaning them up isn't a totally lost cause. ;)

i have always liked the non-egr engines better. they seem to have way less issues with burning valves. i don't run my cars the way you do, though. i tweak them up for higher rev range operation so i don't get real concerned about low end torque. in my estimation, the place for improvement is always at higher revs. 3 bangers come alive over 4000 rpm. :whistle
Offline Profile Quote Post Goto Top
 
PTA2PTB
Member Avatar
I'm totally awesome! I swear.

Is there a better cam profile, than the XFI cam, for low-end torque? I'm going to be installing a 3.52 tranny in my car, too, here in the near future, and I would love to have a cam that would produce as much torque as I can get, up to about 3,000 rpm.
Offline Profile Quote Post Goto Top
 
Murf 59
Member Avatar


DanO leave that unit alone for now. Practice on a EGR unit. Pull the EGR and put a small steel freeze plug in its place. Works great. Do the min match porting, remove some of the crap in the runners and see what how it works. If you fuck up an EGR manifold, no harm no foul. If you fuck up the one you really want to run in testing, its hard to come up with another. Opening one of them up like I did on the Dark Starr project was for all out get it on high end revs. That will not help MPG.
Offline Profile Quote Post Goto Top
 
Crvett69


is the carborated intake that comes on JDM engines any better than the stock FI units?
Online Profile Quote Post Goto Top
 
1 user reading this topic (1 Guest and 0 Anonymous)
« Previous Topic · Fuel Economy/Performance · Next Topic »
Add Reply