When Bigger ISN'T Better: Plenums AKA Intake Manifolds
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- Опубліковано 5 чер 2024
- The bigger your throttle body and inlet manifold is, the more air your engine can flow, the faster you go right? Yeah nah.
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A guide to throttle body sizing, getting even air distribution within 1%, major design considerations, intake volume vs capacity and if an intake/plenum chamber alone is all you need to make more are all topics Shannon Rogers from @PlazmamanAus runs us through during our visit to The World Time Attack Challenge where the team was supporting a new Mitsubishi Evo X product launch.
Where he and the Plazmaman team see the limitations of factory setups is also discussed along with how some head designs and packaging issues just don't allow better solutions as well as a the golden rule Shannon tries to get customers to follow which is to focus on the best combination for the application, not just a combination of the biggest parts you can find.
With this in mind an aspect that is so often overlooked when focusing on the shiny things under the engine bay is also discussed with engine builders and tuners alike forgetting to address the pedal ratio when drastically changing the inlet setup.
If you only take one thing away from this interview it should be that going for the biggest intake manifold chasing the biggest power number you can on the dyno is going to get you a nice piece of paper (noting there's always a bigger fish!) and a probably horrible car to actually drive.
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TIME STAMPS:
0:00 - Common Upgrade
0:23 - Shannon Rogers - Plazmaman
0:58 - Main Design Considerations
1:37 - Reasons To Upgrade
2:04 - Aesthetics
2:21 - The Only Mod You Need For More Power?
4:04 - Design & Validation
4:50 - Overall Power Isn't Better
5:24 - Inlet Runner Length
6:31 - Volume Vs Capacity
7:09 - Throttle Body Sizing
9:09 - 800hp - 1000hp - 1500hp & 2200hp Sizing Examples
10:22 - Pro Tip: Measure Pressure Drop BEFORE Changing
11:08 - Fuel System Restrictions
11:49 - Fuel Distribution Concerns: Dual/Staged Injection Setup
13:33 - Flow Distribution: Within 1% Where Possible
14:40 - FG Manifold Example
15:01 - Don't Assume, Get Some Data
15:20 - Plazmaman, They're Everywhere
15:38 - Thumbs Up, Learn More. Do It. Now. The Old You Would Have.
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#highperformanceacademy #plazmaman #intakes #plenum #intakemanifold #dangertomanifold #wtac #enginesetup #learntotune #enginebuilding101 #dontletthesmokeout #wiring101 #dieseltuning #datanerd #gofasterwithdata #racecraft #learndriveoptimise #motorsports #plazamamanracing - Авто та транспорт
Check out the previous [TECH TOUR] chat we did at Plazmamans facility. Link at end of video.
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Enroll now: hpcdmy.co/25offytc - Taz 👨🏻
Bigger isn't always better. Glad to hear from a Bloke involved in the trade of manifold replacement. Awersome content as usual from HPA 💯 AUSSIE FAN 🆒🇦🇺
Pleasure to be apart of this, We appreciate the support you guys provide.
We appreciate your time team! Always a pleasure and always some great insight gained from our chats 😎
Thanks for this. Been trying to tell the Honda boys for years that a bigger throttle on a stock Honda isn't going to make it faster, it's an uphill struggle though.
70mm throttle body on a 1.6 single cam🤣 all too common
It can, but it's like he said, it's all about air velocity, not air capacity. If by increasing the throttle size you increase air velocity, then you'll increase power.
Always an issue with Honda’s, always an uphill struggle as the engines just don’t have the torque to get up hills 👀🙈😂
Depends on rpm more than anything
That throttle response is the real benefit
Have been banging on about this subject for a long time.. specifically to do with rb25s and the greddy style manifolds.. even with bigger turbos say my gt3076 vs a gt35 making the same peak power at same beak boost the difference in power under the curve is far superior on a standard manifold. Sure eventually the other type will allow more and if your worried more about the way it looks ok.. but for a street car... 💯 No point.. better to spend money elsewhere
Funny you should say that because I spoke with Shannon in 2006 at his place about making me a custom intake manifold when he was still working out of his garage. He was already doing a short runner manifold for the SR20, but I really didn't like the look of it. It had similar runner length to the Greddy manifolds with a different plenum. I wanted something slightly different. I wanted a longer runner like that which was originally fitted to my 180sx. What I was looking for was something a little bit shorter runner length, but with a bigger plenum to fit a larger throttle body. He was asking about $1000 for his manifolds and I really couldn't see the value in it since it really wasn't what I was looking for, so I wound up getting a Greddy copy for it. In hindsight I really should have put the effort into making the intake manifold I wanted in the first place, as the idle vacuum really sucked (not in the good way) with the big cams I had in it. I whole heartedly agree, those really short runner manifolds are not good for 99% of the driving you do.
I did back to back dyno testing on an sr20 with a greedy intake manifold vs the stock s13 long runner style inlet manifold. The greedy manifold made 15hp more up the top, but lost so much midrange. I didn't think much of it as I had a big turbo on it anyway, but when I took it down the drag strip I went backwards by a couple of mph due to the loss of that midrange. This was for a 450rwhp setup running petrol in 2006 or something.
Excellent point that is lost on so many. Bigger is not always better. Bigger often makes it lazier and less fun to drive. Maybe it makes great numbers on the peak of the dyno, but if you lose all of your low and mid-range power to gain it, was it worth the trade?
Perfection is striking a balance that gets you the most improvement through your usable powerband.
Most cars with turbos don't have a midrange, if you aren't spooling up the turbo until after 5k rpm anything under that realistically doesn't matter as you aren't making any torque to lose.
@@ezmny1387 I completely disagree, most modern turbo cars are full of midrange power. My turbo vehicles start spooling at 1800-2100 and pull hard to redline.
The only turbo cars starting to spool at 5000 are old-tech 1970s cars and drag cars with huge turbos.
The Plazmaman intake manifolds for the 4G63 are odd designs. The long runner manifold is marketed to suggest more midrange torque due to the runner length but it has a massive internal volume. Their site suggests this is to support rpm in the 10,000+ range. If you’re spinning the engine that high, why the long runners? The other design is much closer to the Hypertune manifold with short runners which favour top end power but this has a small(er) volume which according to plazmamans long runner marketing would not be ideal for high rpm. I called the them to discuss it, and the bloke was like yeah nah they’re both good aye. Couldn’t give me any practical advice on which one would suit my aims, but did say the long runner version made over 800hp… confusing AF.
While I wont list all the specific measurements a 4g Mitsubishi intake I developed in 99-2000 is contrary to most current intake manifolds being marketed.....larger plenum....large throttle body....and(contrary to popular marketing) long runners....very long.....the one hint I will give is the intake was built to second order harmonic .....added enough to whp and tq that we ran out of injector in testing on an 8 injector set up of the time.....same boost level added over 110ft lbs tq and over 160whp....next closest aftermarket intake only added half that....short runner intakes in most cases are crap .....shiny trinkets....automotive jewelry that do nothing for performance or very minimal gains!!!
I'm sure you get this all the time, Andre, but you're such a good interviewer! Very professional and genuinely interesting and relevant questions!
OMG OMG OMG!
I'm SO happy this videos are back!
Us too! Enjoy 😎 - Taz.
Awesome work Shannon!
Works good if you are pushing in enough air aka PSi.
Of course the fun part of this is figuring out where that line is. Whether you want a flat torque curve or something that will spike.
If people read HVAC standards and Air Velocity standards based on fittings it will work beautifully on induction system...as well as exhaust...you gotta know what are velocity reducers like elbows are and tight bends and by how much...whats the target requirement or air velocity and how are all the fittings together cause pressure drop. Ashrae standards are great resource.
I have regularly checked my plugs every 1k miles or so to adjust cylinder fuel trims, with a stock runner/replenum and 23psi I still ended up around 5-6% on one or two cylinders until the plugs started to look similar. I wish I knew how the factory manifold did, it may have performed the same.
Very informative.
Thank you.
Great interview , very informative
Glad you enjoyed it Andrew, cheers for the comment 🤘
Nice input
Awesome vid this one
Taz from a tuning aspect what have you noticed you had to change in the tune when upgrading the intake manifold? Timing, fuel, what area of the powerband? Since many new cars are direct injection, ports for additional injectors are now integrated in these aftermarket intake manifolds. I see billet, cast aluminum, and combination of aluminum and carbon fiber. Also new cars are using plastic intake manifolds that I noticed doesn’t have a smooth path for air flow internally.
Good talk gentlemen!
Hi, great video again! I wish there was more offered for the Volvo 16 valve Red block head. I'm using an old custom piece. It's pretty janky.
Bigger throttle body tuning is easy to get around... Offset the wheel like I did. so you have lots of movement down low for part throttle, and quick WOT at the other end.
I have seen dynos of people adding a bigger plenum and actually losing power, needing to run 3 extra PSI to make the same power of the stock plenum. Dyno on an s2000. A lot of intake plenums are just for looks
They're right on the money when it comes to going too large in the plenum size as well as the throttle. I actually prefer to over size my throttles some as I like a touchy pedal within reason. But going back to the plenum, the Helmholtz theorem is a very good guide on idea size for the application and in my experience, going bigger than needed makes the engine very unresponsive and soggy to drive, even with a larger throttle in the mix.
With throttle size, I generally used a program like dynosim to simulate where a throttle starts to choke, then pick the size a few mm or closest above the min and use that. The power figures mentioned for throttle size in this video are a foreign language to me, since I only have built and hotted up NA engines.
I found at least with sims and actual real dyno/road testing on some engines, 60mm NA is good for around 300hp, 65mm was good for 340hp and 70mm could support 400+ pretty well unrestricted. I never went any further than that since my engines can't support or even will need anything bigger than 68mm in real life. When boost is added, the stock 60mm is heaps as mentioned in the vid.
I love the Plazmaman manifolds, quality is absolutely amazing! I just got my Plazmaman manifold in for the 1997 1FZFE Land Cruiser that I am building!
Nice one, what are your plans for the Cruiser? Hope you're enjoying the build! - Taz.
@@hpa101 It was a very run down 1997 when I purchased it a few months ago. I stripped the interior and will be replacing carpet & leather, front and rear axles are being rebuilt, cylinder head is being fully machined and rebuilt along with new springs. Engine block seems okay, will be cleaning it up along with new rod bearings. Then the Plazmaman intake manifold, custom air to water intercooler and piping. Planning on Haltech 2500 and 2GRFE coils to replace the distributor. For the turbo I have not decided yet, I think possibly a Borg Warner S362SXE. Larger injectors and fuel pump. And of course a full custom 3 inch exhaust and tune to finish things off.
Suprising to hear a 4psi drop across the throttle body is OK. Did I misunderstand?
Been porting engines for a long time. When it come's to intake manifolds the 2 most important things are "smooth" airflow, and cylinder equalization. You want all air turns to be as smooth as possible with no turbulent ridges or "steps" in between parts. You want all cylinders to have equal flow from the air source all the way through the cylinder head and out the exhaust, and the intake manifold is the first critical piece to accomplish this. As far as plenum capacity things get a bit more complicated but you want to essentially do is "shape" the plenum to make sure the back cylinders are getting the same airflow as the fronts and can meet the flow needs of the cylinders. This will determine the size and shape of the plenum based on the application. Bigger is not always better.
Have you found that these wedge shaped manifolds make much difference compared to a evenly shaped one ?
Researching is the hardest part I find . Trying to find the right video with ideally a 3d diagram of how the air is flowing through the plenum evenly to all cylinders with no steps or turbulence like you said . Finding the right video with that plenum . I'm sure there are alot of plenums that are not like that
@@TheRobphobos This is basic fluid distribution topic. The header should have overall low dynamic pressure to ensure better distribution. The tapered kind ahieves this but also reduces materail use and gives overall better aestatics.
Too little attention is given to the exhaust manifold - but cylinder airflow distribution depends on both.
The best would be to do a "Z" coupling - meaning the cylinder with the inlet closest to the inlet of the air-manifold should have the longest distance to the outlet on the exhaust manifold. Then the air-flow should be more balanced as resistance in the manifolds are more even.
The issue I've found with these have been the plenum runners. Motive showed in their video they had only 22mm runners which is ridiculously short and only good for top end. I've also seen dyno results from Goleby on a 1JZ that he put up on FB and the loss of power under the graph was more than the top end gain you got. 👍
What engine? Is it a case of physically not being able to package it different as Shannon discusses? Can only work with what is there bearing in mind it is something you can discuss before pulling out the old wallet too in order to weigh the options up - Taz.
@@hpa101 My bad Taz with the Motive one, I messed my brands up as it was Hypertune on their 3.2L RB26. The Goleby dyno result was Plazmaman.
Assumptions are the mother of all fuck ups 👍
Nice👍
Such a misunderstood topic! This was a great discussion!
With e-throttle, can the negative effects of oversized throttle be tuned out? Eg: 50% pedal travel = 12% TB opening. And we get to keep all the benefits of having less pressure drop thru the TB?
One question about an info in the video, when he says about trottle body inside diameter, 60 mm good for 800 hp, 72-74 mm good for 1,000 hp, 85 mm good for 1.500 hp, and 90 mm good for 2.200 whp. All power ratio are at the wheel I suppose?
Their stuff is cool and you can see the quality but damn is it hella expensive!😢
Andre is the man
wait... a 4psi pressure drop across the TB is reasonable? That sounds WAY larger than I'd expect. I would have expected even a 1psi drop to be an indication of an undersized TB.
My thoughts, and they're basically discussion points -
That IS way, way over what I would have expected and I'd seriously question the wisdom if the person was citing it for a lower powered vehicle. However, the examples he cites are bit more than 'normal' vehicles, and 'undersized' TBs will give a lot more control at the cost of a few hundred horsepower which would still leave way more than the street could take.
Perhaps an option for the very high output setups, of the chaps and chapesses, would be to have a smaller TB for the street, with a street tune, and the larger/est bore for the strip where it would be running a high power tune? With quick release couplings, it should just take minutes.
For comparison, the airflow rating In the USA for four barrel (4bbl) carburetors, which one would expect to be the street 'performance' option, is at 1.5”Hg (20.4” H2O.) through the carb' - that is 0.736731 PSI. For a little more top end, some will upsize a little from there. Remember, that's with a bunch of restriction and a drop being required for the venturiis to work. They will normally offer very good driveability at that drop.
HOWEVER, the turbo' has the spooling issue where the actual torque can rapidly change between off and on boost, and those torque levels will be MUCH higher that a similar N/A engine can produce.
For an average street engine, perhaps just using a TB of the same ID as the plumbing (which should also be sized for the application) with either a progressive mechanical linkage, or electronic' mapping, to give a slow initial opening for better throttle control at light openings, and faster opening close to WOT, would be best?
@@gordowg1wg145 can you tell me what pressure drop is used for 2bbl sizing? My recollection is that a 2bbl carb flows less than a 4bbl carb of the same CFM rating.
@@totensiebush
"1bbl and 2bbl carburetors are rated at 3”Hg (40.7” H2O.)", so double the pressure drop of the 4bbl.
Not sure how it works out when running triple (or quad) deuces from back in the day on some of the US engines - whether they're rated as 2 or 4 bbl carbies? There is a conversion one can use to directly compare them, but can't recall what the constant was off hand.
Why aren't there centre feed manifolds, it seems so logical to keep distribution even across the cylinders...or a small throttle bodies at either end...
I think it's flow reasoning.
I've seen JUN intake manifolds on a 3S-GTE motor Gen2 and Gen3 as center feed even in OEM. Apparently, 3rd cyl seemed to always run lean.
For Gen4 and 5,they went side feed OEM.
I think its entirely for packaging reasons. Centerfeeds point the throttle body at Tue engine mount and/or steering column
Nissan RB20/25
Why are cylinders that have less air flow running lean? would they not be richer as they'd be getting same fuel but less air?
Its very simple and most people can't get their head around it , a long runner will always make more power over all and will usually fall off around 5500-6000 depending on the length ofcourse . A shorter will only make more power at higher rpm , there is no sorcery behind it . Your average street driven 500-600hp build does not need a fancy $2000 manifold infact you are actually loosing driveability and power if anything .
Technically you're average street driven car needs nothing, it's what we want that see us do these things 😅
That said I feel part of the discussion covers off what you're trying to say there when they say that you don't need to go massive, but rather really look at what you are using and grab what suits.
That might still be a product that costs you $2,000 as price doesn't really dictate size or performance gains/losses - Taz.
My plenum is the whole atmosphere. I have individual throttles
It's all a plumbing problem both in and out .
You want horsepower or torque ? RPM or pulling power ?
An adjustable intake and exhaust .
Large tube small tube .
The base that bolts to engine off gasket then braze on tubing (brazing or sodering tubing allows easy removal with 2 small welded tacks) same with exaust but need pipe stretcher an exaust clamps .
Temporary to explore your engine !!!
Multiple carbs even a very small single barrel almost lawnmower carb will surprise you !!!
Now this doesn't work too good for cold climates...
Fuel filler hose and hose clamps to play with runner length .
I'm doing a 2.5 liter 5 cylinder with a goal of 700-1000 hp, I got a 74mm porsche throttle body and after hearing this, I hope it's not too big.
I did put a 89mm LS throttle body ( because it was cheap ) on a 2JZ , part throttle and very small throttle opening can be a little bit of a pain . I would definitely go on the smaller side if I could . I think you should be ok with a 74 mm throttle body though.
@@dilsher12 thanks for your insight
As was mentioned in passing in the vid', you can partially compensate by using a throttle linkage that is progressive with a small change in throttle blade angle at small openings and large changes as it approaches full throttle - or mapping the opening against pedal position if DBW.
On that, if DBW, you may find better torque with the throttle blade less than fully open, and you can map to that for a benefit.
@@gordowg1wg145 Thanks for the reminder. Yes, non-linear throttle mapping is a good idea, I just don't want to use it as a "bandaid" for a poor choice in throttle body size. I don't think my choice of 74mm is grossly out of line, maybe just a little on the large side, so probably non-linear throttle mapping will be perfect should I encounter any issues.
Is there any specific rule of thumb when it comes to plenum size?
I for example have a 2L 5cyl that left 230hp and 267nm (calculated crank) but my throttle response is terrible and the theory being that my plenum is to big. How should i go about calculating the volume when i go about building a new intake all together?
Anyone got any info on how one does size plenum chamber capacity for engine capacity?
ITB’s: troposphere manifold y0
Would the throttle body sizing apply to naturally aspirated engines as well? Like if you didn't have the right supporting head mods (upgraded cams, valves, springs, porting), but upgraded fuel system (pump, injectors) it would negatively effect it?
Yes
Without aftermarket cams you're not really using the extra air volume you get from a bigger throttle body. In my experience they make stock engines lazy 😴
@@eddiel4226 thank you I thought that might be the case just wasn't sure
I have 2,3L N/A, higher lift cam, adjustable cam gear, increased compression ratio, racing header, full fuel system,e85,big plenum, long runners, 80mm throttle body and it's a lot better than stock 53mm. Low speed throttle modulation took time to learn but it's really good on half and WOT.
Definitely worth it.
Bet it would be even better with boost.
But ofc it depends on the engine also fuel economy is especially bad because of 80 mm TB. Still worth it.
Am I going to mess up something or do it in vain, if I smoothen and enlarge the stock intake before the air filter and the sensor in a naturally aspirated car? The initial inlet seems small compared to the rest of the system, and it's not located in the stagnation zone as well as it could be. I know the manifold itself is beyond me, but allowing it breathe better before the filter should - at least in theory - do no harm, right?
so what youre saying is, i need 100mm drive by wire on my stock 4ag, good to know 🤣
Brown Mitsubishi scorpion !!!
The bigger, the more you lose down low. But if you're in the upper rpms like for racing then it's an option
FOR GOD SAKE LET THE MAN SPEAK !!!!!
🤐
The bad part about this is the TB stuff is mostly wrong for PD blower guys.
Translation: 90% show and not go. Hey! Understandable. We're only human
“Kegalodon”
Ah yeh m8
Bigger is Always better till you can't control it
Omh that guy is dodging all the questions, they are so interesting but he answers none of them....
An inlet manifold and a plenum are not the same thing.
Agreed, but it is one of those things where language has changed around them to the point people use and understand either term now, rightly or wrongly - Taz.
how come y’all never talk about VWs and Audis?? how come all these tuner programs/schools support so much jdm? honda subaru etc. what the hell?! I wanted to hear about whether it made sense to buy the ECS aluminum gen3 manifold for a Stage 2 vw stock turbo, or the HPA manifold for a similar Audi, stuff like that. There’s a ‘water cooled’ manifold HPA offers for N/A R32 VR6 engines, but its like 4 grand?!? I wanna hear about if it makes sense or doesn’t for those, I don’t own no GTR or some roll caged Honda as a daily driver 🤦🏽♂️😖
Just not as popular at the events we go to. We are adding more tuning courses content using VAG cars this year though.
With the price of the old go to options getting crazy I'm sure we'll see the next generation of popular options come through the ranks more and more and also gain more aftermarket support too.
Note we don't sell anything you mentioned there - Taz.
Useless unless your going 1000+
🤣🤙
Who calls it an inlet manifold....
John, Peter, Brian and a some other casual millions 😎 - Taz.
Everyone in Europe calls it an inlet manifold….because it’s a manifold, that LETs air IN