plenum spacer/s, are they worth it?

[The1]

thread dig and no evidence, pod filters do flow better and can filter much better than crappy paper, i posted evidence of this somewhere ages ago could dig it out if need be.

 

[commodore665]

thread dig and no evidence, pod filters do flow better and can filter much better than crappy paper, i posted evidence of this somewhere ages ago could dig it out if need be.

Very true , cunning sales ploy from makers of pod filters


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[staypuft]

This is an old post but I thought I'd throw in my 2 bobs worth. I put a 25mm spacer onto my VS V6 5 spd (with extractors). Before it went on, the take-off seemed a lot gruntier, with the spacer on it seems to have smoothed the engine. I was still beating everyone away from the lights, but things just seemed smoother (a mate with a VF V8 took it for a blat and reckons I'd beat him through first, but then it would be goodnight from him...).

A few months later I got an over-the-radiator cool air intake on ebay, which brought the gruntiness back to the engine (this isn't subjective, I can definitely feel these differences)

So gut feel is it changed performance, I can only assume for the better (economy-wise it may have given me a few more kms per tankful, but that also relates to how and where I'm driving).

Anyway the boss tells me I get a bonus this year, so I'll be looking to get from Mr Mace a wide throttle body, and maybe that other spacer up top. What else should I be spending money on (lol)

 

[1997 VT Calais Series 1]

I'm shocked to see that some people have no data to back it up themselves, I'm a petrol head like many other commodore owners, and know when there is a noticable difference to my engine performance. But I also know that making any kind of improvements to the airflow will translate to a better breathing car, for example? Before spacers wasn't Port and Polishing the you beaut thing to do?

And coming from the old 161, 179, 186, 202, 253 and 308 era's port and polish did imrove the performance of an engine, it helped the airflow.

So? If I now Port and polish my VT V6 and then add a spacer there should be a noticable improvement in the airflow, and yes I may even through the car on the dyno after the port and polish to see the results, and then run the dyno tests again, then add the spacer and do the dyno tests again. I don't see why some are making this such a difficult subject.

You all should know that any change to airflow will have an effect on your engines mixture, so a re-tune would be a normal process to rectifiy the mixture flow, you may also need to change the plugs? Your improving the cars performance whenever you tune a car and you do this because it falls out of tune due to all the normal running conditions an engine suffers when used. If you want a little more spark you add a decent coil (although they don't call them coils anymore they call them powerpacks right?).

Anyway, this forum should be about helping each other find answers to questions and not about bagging a product that no-one has tested or has test results for. An opionion is just that, an opionion, but bagging a product with nothing to back it up with but there unqualified remarks disappionts me, and I would hope to see more productive input about a subject with real data to back it up from running tests themselves or getting a group together to run some test. If you are all so good at diagnosing faults? Why have you not run tests yourself about this and found all these faults that are mentioned above in this post? If you did run some tests this would prove your point and we would all listen and ask questions. Please help people find the answers to improve there fuel economy and or performance. No-one is asking you to give your secrets away, and I would presume that no-one here is RACING for a living where the edge is needed to win.

Anyway, hope you enjoy this read as much as I have had expressing my thoughts and please don't take this the wrong way, I am not singling out any one individual. As for me, I'm going to do my best to improve the air flow of my cars intake system, and that should improve my vehicles feul economy and performance, granted not by much, but I'm not looking for a lot, I'm looking for clean airflow and a happier engine hehehehe, breath engine breath.

I know from personal experience with a friends VT V6 when he added the Plenum spacer to his Plenum, that there was an immediate change in the engines idle and he also noticed it was a little more responsive and it felt different underfoot and I agreed with him. Whether this equated to extra horsepower was left to be determined because we never got the chance to throw it on the dyno, but it definitely was more responsive.

 

[harrop.senator]

Polishing the ports is very 80's and a waste of time. Porting isnt though still works well. Had a friend put these on his car butt dyno said small increase they make a huge difference on the Super 6's though.

I wouldn't bother paying for porting and do it yourself. If you pay someone else to do the work and buy all the spacers etc you'll be up for more then it'd cost to put a supercharged Top end on the car.

Ive got an ecotec in my car the shop charged the guy 5k to build . It's got ported heads , a cam , mm over size taking it out to 3.9 , shaved heads , extractors full exhaust and a retune and makes 180rwhp. The same amount of hp as a $600 Top swapped ecotec makes with a ten pound pulley and a whole heaps less torque. Unless you're doing all the work yourself and fitting a $150 reground cam theirs definitely cheaper ways to find more power forcing it.

 

[losh1971]

I've used TB spacers before with some minor increase in performance in acceleration. AFAIK same goes with better shaped plenums, especially if you can get one that holds more air. I had a upgrade plenum for my old Jeep but never got around to fitting it. But all reports I have heard of those who used one said it definitely makes a diff. AFAIK dyno results won't show improvements on HP using a TB spacer. The science behind it also says it can not help. But I definitely noticed an improvement with acceleration. Other mates have reported their wives as saying "why is the car feeling like the handbrake is on" when TB spacers are removed.

 

[losh1971]

I spoke to our local engine builders and he said polishing ports will make a diff. He told me that an engine place in Melb did the tests. Having said that he also said the increase in HP just through polishing was minor and not worth it because of the time it takes. But fitting larger valves made a noticeable difference.

 

[1997 VT Calais Series 1]

I spoke to our local engine builders and he said polishing ports will make a diff. He told me that an engine place in Melb did the tests. Having said that he also said the increase in HP just through polishing was minor and not worth it because of the time it takes. But fitting larger valves made a noticeable difference.

Hi losh1971,
Thanks for your reply, and Yes your engine builder is correct but?
I'm not doing the port and polish for horse power,
I am trying to create a more efficent airflow into the intake manifold for fuel efficiency.
I want to see what I can do to improve the vehicles fuel efficiency without spending bucket loads of money.
I am starting at the throttle body and looking at what I can do there?
I'll then making way into the Plenum.
Then I'll move to the Inlet Manifold.
I will add a 12mm or 25mm MACE Inlet Manifold Insulator spacer but I have not decided which one yet? Because I have been told by a few friends that if I add the 25mm Inlet Manifold Insulator it may hit the bonnet when I put the engine cover back on and I want it to look original. So? I think I have to think about it for a little while as the 25mm is more expensive as well, and I want to keep the costs down as much as possible.
A friend of mine added a 12mm MACE spacer to his Plenum and got a noticeable change immediately, it was more responsive and he said? He just has to touch the excelerator now, where before he had to push the excelerator a little. He has not port and polished anything, and he has not tested it either, to see if there is an increase in horse power, but I don't think he cares hahahaha, it put a smile on his face so that is just as good. So now? I want to do it for myself and see if I can improve it without spending a lot of money in the process, just my time and effort and a little money here and there.
Also? I think he should have added the Insulator to the Manifold and not the Plenum, but that's just my way of thinking, it could work just the same, But maybe I can add both? I will see? At a $135 for the 12mm and $185 for the 25mm, I really have to think about it? Or run one and add the other later? We will see.
But anyway? I'm having fun in the process and it's not costing me an arm and leg, Plus I hope someone eles can get a benifit out of my experiment.
Also? I another thing that caught my interest was the High Voltage Coil Packs? The feedback I am reading seems to suggest there is a benfit there as well? But I really have to consider those as they are very expensive, and of course in combination wiith all the other changes I make.
Anyway, enough ranting and raving.
Hopefully I can do some testing, but time is an issue.
I am trying to achieve all this with as little cost as possible.
Doing the work myself, and as I mentioned before, this is not about horse power, it's aboy fuel efficiency. I do realise they I may gain a little more horse power but I really don't think it would be worth testing for as it would only be around 5-10 kw and that's nothing to write home about, although I will be happy. but other would not be, hahahaha All good.

 

[1997 VT Calais Series 1]

I've used TB spacers before with some minor increase in performance in acceleration. AFAIK same goes with better shaped plenums, especially if you can get one that holds more air. I had a upgrade plenum for my old Jeep but never got around to fitting it. But all reports I have heard of those who used one said it definitely makes a diff. AFAIK dyno results won't show improvements on HP using a TB spacer. The science behind it also says it can not help. But I definitely noticed an improvement with acceleration. Other mates have reported their wives as saying "why is the car feeling like the handbrake is on" when TB spacers are removed.

Yes losh1971, I have heard the same, I think someone mentioned that to me, that it makes the fuel mixture run a little lean and that is similar to a small advance setting in your timing, but not sure on that one though, I need to do more investigating. hahahaha, more fun.

 

[1997 VT Calais Series 1]

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.

Thank you very much for your 2 cents worth Irukanji, because what you say all makes sense to me, I'm not looking for horse power I'm looking for fuel efficiency and if there is a noticable improvement in the responsivness? then that means I'm saving fuel because i'm not pushing the pedal down to use up more fuel to get the car going. Just what I wanted to hear. Thanks again.