plenum spacer/s, are they worth it?

[Irukanji]

I have no evidential experience, but common sense tells me a large plenum chamber will improve acceleration. Now, before you jump on my nuts and say "prove it", think of it this way.

You put your foot on the accelerator, but there is no oxygen. The revs climb slowly, it slips into second(auto), and then your acceleration is gone because your trying to get acceleration out of a gearing designed for a higher speed.

Now, you increase the size of the plenum chamber, and you have the air available. Ram air intakes(think ramjets, not those cosmetic scoops) are designed to deliver as much air as possible to the combustion chamber, and the sensors adjust accordingly. Increasing the size of the throttle body allows more air to flow, but there will still be a slight delay between opening and air actually flowing past in the required volumes.

However, insulating the plenum isn't required. It's made from thin aluminium, you have a large air flow going through it, and so the temperature should sit around the same. Besides, the bonnet has insulation which traps heat, so the plenum is going to get hot regardless of what happens. The heads(which the manifold bolts to) are cooled by water(or glycol + water or whatever you want really), and the average operating temperature is around 120 Celsius with a considerable amount of force. So you could run a faster water pump and a cooler thermostat(I've seen 82C being the standard upgrade), which will bring the temperature down more than a piece of silicone will.

But definitely a bigger plenum. Hell, for 50 bucks and a weekend, you could braze together some sheet metal into a new plenum, with none of the dead air pockets, and all of the space you want inside of it. But that requires effort, and it's going to be easier to undo a half dozen bolts and stick a piece of precut rubber in there and then bolt it back together.

Besides, I'm willing to bet the single plenum spacer gives better gains, theoretically, than any pod filter yet people still fawn over them.

Not defending MACE or anybody else, just offering my 2 cents.

 

[Customcreations]

In regards to parts for testing, there is a possibility we could work something out I guess depending on what it was and how it was structured. I can't promising anything though. Best to draft something up in an email

As Jonah 101 has mentioned, we recommend a 12mm plenum spacer and a 25mm manifold insulator. Running a 25mm plenum spacer can reasonably dampen throttle response, however running a larger throttle body a revised tune does sort this out.


Thanks for the reply.

I might try emailing you. Being a NOOB to this in the forum sense. Do I remember that MACE is based in VIC.

Also as for as dyno testing and tuning. That is something Iwill be needing to do as I am converting to manual, but more important Is I am making and adaptor plate to fit a 6 bolt flywheel (series 1 VN manual donor part).
Not with a grinder though. :lol: I Have a lathe for that part.
The 6 bolt is heaps lighter and has less "meat" at the outer diameter as you would more than likely know.
Plus the other mods I have mensioned (porting and exhaust sytem) wont go into depth on that.
When finished which should be in next couple of days I will see how it goes and then decide what to do.

I will definately go the 25mm intake spacer (it will make a nice 40th birday present for myself. I know the wife wont buy it for me)
but in a couple of weeks or as soon as I sell the VS 8 bolt flywheel /or the whole spare manual conversion kit I have put together. (VS or VN optional)

 

[Customcreations]

I have no evidential experience, but common sense tells me a large plenum chamber will improve acceleration. Now, before you jump on my nuts and say "prove it", think of it this way.

You put your foot on the accelerator, but there is no oxygen. The revs climb slowly, it slips into second(auto), and then your acceleration is gone because your trying to get acceleration out of a gearing designed for a higher speed.

Now, you increase the size of the plenum chamber, and you have the air available. Ram air intakes(think ramjets, not those cosmetic scoops) are designed to deliver as much air as possible to the combustion chamber, and the sensors adjust accordingly. Increasing the size of the throttle body allows more air to flow, but there will still be a slight delay between opening and air actually flowing past in the required volumes.

However, insulating the plenum isn't required. It's made from thin aluminium, you have a large air flow going through it, and so the temperature should sit around the same. Besides, the bonnet has insulation which traps heat, so the plenum is going to get hot regardless of what happens. The heads(which the manifold bolts to) are cooled by water(or glycol + water or whatever you want really), and the average operating temperature is around 120 Celsius with a considerable amount of force. So you could run a faster water pump and a cooler thermostat(I've seen 82C being the standard upgrade), which will bring the temperature down more than a piece of silicone will.

But definitely a bigger plenum. Hell, for 50 bucks and a weekend, you could braze together some sheet metal into a new plenum, with none of the dead air pockets, and all of the space you want inside of it. But that requires effort, and it's going to be easier to undo a half dozen bolts and stick a piece of precut rubber in there and then bolt it back together.

Besides, I'm willing to bet the single plenum spacer gives better gains, theoretically, than any pod filter yet people still fawn over them.

Not defending MACE or anybody else, just offering my 2 cents.

Lets not start on pod filters PLEASE.
They are notorious if not looked after. But really I'm not going to start. If I find the thread I'll paper clip it for you to read. I've replied in that thread about my experiences with them. Not my lazy maintenance though. It came on the other MODDED car I bought. (Mitsubishi TRITON 4X4 with Buick 3.8l series 1 manual conversion).

 

[Z2TT]

So from what I've read on this thread i've summed up a few things and also got some questions for MACE.

- 12mm Manifold Spacer and 25mm Inlet is the best combo with minimal drawbacks? 25mm manifold spacer would decrease throttle response and require tuning.

- Some people have mentioned bad idle after this, Steve/MACE mentioned it could have been because of a bad air leak but mentioned they should inform people about the issue.... Steve have you experienced bad idle when installed properly and would this definitely be a problem for everybody who purchased the manifold spacers? I would definitely think it could affect idling since it's modifying the design of the intake but correct me if I'm wrong.

- Since it gives better power in the low end (by making runner length larger) would it take away from top end at all?

- Can you run the Inlet manifold spacer without a plenum spacer? Would there be problems in doing this as it was mentioned the plenum spacer is to control lean outs on certain cylinders?

- It was mentioned the manifold spacer (or more so the plenum spacer) improves fuel economy, some people even said 20% which seems pretty remarkable I think if it's true..... but would this be caused by a leanout created by changing the length of the runners, capacity of chamber etc.......... AND is it leaning it out too much making it dangerous for example dangerous enough if some fuel happened to be poor quality.

- All that being said, is it safe for 91 RON petrol, I'd assume most people here who are into performance would insist on using 98, but can these spacers be used safely on 91?

- Lots of us might have older cars where the coilpacks might not be in top top notch? If these spacers do make the engine run leaner a bit could it be a problem with old ignition parts?

Anyway last of all if somebody can do a before/after dyno on the same day with a good condition stock Ecotec powered car, this will put all this argument to a rest.

Cheers.

 

[HERONVY]

Oh no, not someone asking valid questions about maces product testing!

What has this world come too.

Personally. i find the idea of having, what looks like a piece of mdf wood (i know it isn't but it sure as hell looks it) sitting near my engine, somewhat uncomfortable

Oh well, not my car so not my choice.

And HERONVY stop trying to be a hero.

Im not trying to be a hero bud, I just think that you shouldnt be lodging an all out assault on someones company when you havent tried their products....

 

[UW1SH]

Lol this is still going haha funny

 

[Jonah 101]

Lol this is still going haha funny

I know, Im surprised too.

Glad everyone seems to be remaining civil about it though.

 

[some_guy]

Im not trying to be a hero bud, I just think that you shouldnt be lodging an all out assault on someones company when you havent tried their products....

It was hardly an all out assault. But that's only my opinion.

I have critiqued the product in regards to its results, just by looking at it I made that observation.

I think it was a good well constructed argument by both sides. A good read.

 

[Irukanji]

Lets not start on pod filters PLEASE.

I never advocated pod filters. When I was young, sure. But only because they looked cool. The stock air filter is already oversized, I'd take a guess at about 5-6x the size of the intake tube(between the MAF and the TB). You can pull more air through that than most people think. Even completely clogged, they can supply enough air to get you past redline. Then you get into the story of high-flow filters. Higher flow = bigger particles can get through, and you'll gain zip. They don't get as dirty as the paper ones because your motor is keeping it clean lol. Dust with oil is a great polishing compound.

 

[commodore665]

Nice thread dig


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