Dohc g63 plenum. Which way did you go?

[75glnt]

Hey guys.. This is to the guys who have done the rwd conversion. What way did you guys go with the plenum?

Cut and shut? If so, how and how much?

Another way? If so, how?

[Tj.]

The guys on projectzerog and austarion often use custom made plenums with quite short runners (may not be the best for NA, they're all turbo builds) but I had a friend who could weld aluminium cut n shut it. If you go through my build thread there'll be some photos. It's not pretty but it works. Just make sure thay if you're leaving your coil packs in the stock location you'll need to extend the plenum out a bit further or your throttle body will foul it.

This would be a good opportunity to think about where you're going to put your airbox and think about angling the throttle body to suit. If you're running a stocl computer like I did you'll have to run the stock MAF which can only operate inside the airbox. Really damn annoying if you're short of space. Turbo MAFs and airboxes may be different.

As for the other end just make a flat plate and bolt it on. Make sure you use a gasket and some compound to seal it up.

[75glnt]

Hmmm... I seen an adapter loom for an apexi ecu. From the old ecu connections to the new ones.. Would it be worth doing that??

[75glnt]

Far out! I might just save up and buy one

[75glnt]

Will get onto him cheers mate

[A112H]

Or you could just look at my thread, lol

[A112H]

Not a great pic but I am thinking about getting a different manifold modded to suit so this may be for sale if you are interested??

[75glnt]

Very intersted!! Post it with the extractors haha! Kidding but yea mate! I'm keen!

[dwlee]

Evo 4 inlet on a RVR small port head (same as an Evo 1-3 head).

[75glnt]

So that is an oem part that is unmodified? And will work on my engine?

[A112H]

Pretty sure they don't just bolt on but more than happy to be proven wrong.

[dwlee]

The evo4 manifold needs the holes for the injectors in the manifold to be blocked(jb weld or welded) and the flange needs to be trimmed at the front so that it doesn't hit the back of the timing gear cover. The top of the flange also has to be trimmed so the injectors can be fitted into the head. On the head the egr port needs to be blocked. The manifold ports will line up correctly, but is only suitable for small port heads such as evo 1-3 and per 1996 rvr. On large port heads, like a vr4 head, the bottom of the ports in the head would need to be filled.

[75glnt]

Hmm thanks for the info. But I'll stick to the standard one, seems like less of a hassle

[Tj.]

Here's a close up of my manifold. It looks dodgy but it works and took very little fabrication (not that I did the work myself anyway)
It's a stock Sonata manifold (don't know if it differs from GSR manifolds but I don't think they do) with a flat plate on the back end of it. To relocate the TB the end of the plenum was chopped off (you can see where it tapers in) and then a short piece of tube was welded on with a flange to bolt on the stock TB. I mounted the TB on it's side so I could get a throttle cable to it. That bracket is not what I ended up with by the way. It was an early design that I junked.

Like I said its not pretty but it works, and most importantly for me it worked with stock parts.

[Tj.]

Found another shot. Here you can see where the coil packs, still in their stock position tuck up under the TB.


Here's how it all looked in the end. You can see the completely different bracket for the throttle cable. The airbox plumbing is far from ideal but there's so little room in there that I didn't really have an option and I was running out of time and just wanted it to run. It's something I'll address in the future.

[75glnt]

What's the air box from? I'm thinking of finding the cheapest square type k&n filter I can and build a box to suit.

Thanks for the pics by the way makes more sense that way rather trying to explain it

[Tj.]

That's the stock Sonata airbox. Galants (should) have the same. They have a large cone type filter that you can get K&N's for but it was a bugger to actually mount in there. There was nothing to really attach it with.
I originally wanted to use a Commodore airbox as they're nice and compact, cheap filters and can be modified to redirect intake flow pretty easily. But the big hurdle that I just could not work around as the MAF.



They look like this and actually mount inside the air filter. There's no way to make a later style in-line (inside an intake tube) work without using an aftermarket computer. For me to run that setup would have added thousands to the build for a new MAF, ECU and then all the tuning the new ECU would need to get it running. By keeping the stock components I kept costs waaaay down and one the final wiring was completed the car started literally first go. It's fiddly but like I said, it saved me heaps of money and made the car super reliable (I'd been told by several people that aftermarket ECU's get stroppy).

What I might do next time around is custom fabricate an airbox that will connect to the TB with one simple silicon hose (as opposed to that flexible shit) and have it house the stock MAF and either run the stock filter or accept a panel.
That is if I don't get too carried away with some other ideas I have

[75glnt]

By MAF I'm assuming that's a mass air flow sensor? And what do they do? What do they look like? And where are they on the g63?

[IncorpoRatedX]

similar to the evo 4 inlet manifold, i used an evo 8, welded injector bungs shut, trimmed the EGR port, put an egr block off plate on, I already had an early 90's 4g63 head or i would have used a later 90's 4g63 head (smaller ports, match evo intake) so i used a flange for a small port intake manifold, milled it to transition to the large port cylinder head, it's not high performance good, but it's plenty good for the way it is.

[RaptorReed]

By MAF I'm assuming that's a mass air flow sensor? And what do they do? What do they look like? And where are they on the g63?

Located just before the filter on the intake. The ECU needs it for calculating the proper air/fuel mixture, the MAF calculates the amount of air that enters the intake. On a turbo setup, this is why the bypass valve recirculates the discharged air from the turbo back into the intake, because the ECU is expecting that same amount of air in the system. So when someone decides they want to improperly vent to atmosphere on the stock MAF, the ECU still thinks it's getting a set amount of air when it really isn't and instead floods the engine with fuel and often times the engine stalls. Usually upon a downshift coast.

Proper VTA is with something like a GM 3" blow through setup or Speed density with a MAP sensor. MAP sensors constantly guestimates air density vs having a set value of expected air each time. In a turbo setup with a MAF, if you blow a intercooler coupler, it won't run. In a MAP setup, you can drive the car still, just build no boost lol.

[75glnt]

Right... I kinda understand the maf now so I'll keep everything stock between the tb and filter. Thanks

Does mine have a map?

[RaptorReed]

No you would have a MAF, MAP/Speed Density is a conversion. Evos had a MAP sensor on the plenum and then a MAF, but the MAP sensor was used inline with MAF or whatever. Most common sensor used for converting with is a GM 3 Bar MAP sensor. However, before you would consider this idea, you would need some way to tune the engine to the new setup.

[75glnt]

Ah.. Ok. I'll leave that bit alone for now thanks for your help!

All I've gotta do is find a matching tb for my manifold. I still haven't tested my standard one yet... I don't really wanna be pulling crap apart and not knowing how it goes back in. I really need a manual of some sort for this engine.. I don't know what anything is. Apart from the usual bits I'd find in a pre 80s car..