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Multi Throttle Bodies vs Single Throttle Body

43K views 90 replies 18 participants last post by  joshuaho96 
#1 ·
Hopefully a healthy discussion based upon facts and not opinions.

When it comes to naturally aspirated and turbocharged vehicles alike, it is hard to beat the response and efficiency of individual throttle bodies. Unfortunately because manufacturers often tend to prioritize cost over Peak power, individual throttle bodies are a rare sight in factory equipped vehicles, and generally limited only to the highest performing models such as the BMW M3 and Nissan Skyline. When cost is no object however, individual throttle bodies have several distinct advantages over their single throttle body counterparts.

Single Throttle Bodies

Most vehicles come from the factory with a single throttle body primarily due to cost concerns, as individual throttle bodies tend to be far more costly and contain far more individual parts. In a single throttle body design, air rushes into the intake manifold’s plenum when the throttle is opened. While the response is relatively quick, there is still a brief pause between the time the air rushes into and fills the plenum, and when it actually runs into each cylinder. No matter how well tuned the engine is, or how balanced and blueprinted its components are, this lag will always be present, however miniscule.

Individual Throttle Bodies

In a vehicle equipped with individual throttle bodies, the plenum if equipped, remains full of air whether the throttle is open or closed. Because of this pre-filled state, there is no wait when the throttle is opened, and air rushes directly into the engine, resulting in a crisp and responsive throttle. In some extensively modified, naturally aspirated engines, the plenum may be removed altogether, allowing room for tuned velocity stacks designed to compliment a specific power curve and make more useable power. In high horsepower engines, individual throttle bodies also tend to flow air more efficiently, freeing up power and complimenting high lift cams or high levels of boost.
Physics dictate the above which is a given, there is no possible argument there.
So on to the concerns...

Potential Concerns

Individual throttle bodies, when run without a plenum may be more susceptible to dirt and dust and excessively loud for street use. These engines should not be operated in areas of excessive dust and dirt without adequate filtration. It should be noted that for vehicles equipped with mass air flow sensors, a sealed intake system will be required for proper operation, as is the case with Nissan’s RB26DETT engine, which is equipped with a standard plenum style intake manifold equipped with individual throttle bodies. Individual throttle body kits are generally very expensive due to the precision and machining required. Often at times as much as 3-6x more than a comparable single throttle body upgrade. Because of the limited power increases they may make with an otherwise stock engine, they are often times better suited as a finishing touch rather than a starting point.

The power your engine can generate can be limited by restrictions and inefficiencies. At stock power levels, these restrictions may not be apparent. But in a highly tuned engine, they can become severe bottle necks to airflow, and thus largely reduce power. Individual throttle bodies not only offer superior response, but they also reduce these restrictions, freeing up power through improved airflow, with little to no trade off other than cost and increased engine noise.
So at what point does a single throttle body become more efficient than individual throttle bodies?
 
#5 ·
It's a good discussion point but is there any documented evidence for either option? Even if there is, there will always be advocates of both. It's a bit like the 4 valves per cylinder vs 2 valves per cylinder argument, both have their followers and they will never be swayed by the arguments of the other side.

Let's see what this thread turns up.
 
#6 ·
No, I'm led to believe that there is real life evidence to support this Tazz, although I'm yet to see it. I keep getting told that the efficiency of the single is better (possibly at WOT, I'd like to see evidence) and that the standard multiple throttle bodies cannot support large power applications.

Well, I can kind of counter that as my car makes more power on the standard throttle bodies than some running singles, so as I've not yet reached the point where the standards are creating the restriction, I'd like to see what makes people think they need to downgrade to a cheaper alternative.
 
#7 ·
Matt I spoke to pete at hypertune about multi tb and single and he said he would remove the restrictive multi tb on any rb26 over 400hp now hypertune are classed as the best in the business all over the world. Considering the sell multi tb plenums and singles do you think the have a reason to talk people into singles?


That backed up with what amt have shown in flow charts should be enough to convince any one.

Last year I had multis now I have a single bearing in mind mine is 100mm so more focused on drag than circuit/road. What I can tell you is my engine now naturally revs ALOT faster I don't mean high rpm I mean from 1k rpm onwards.

The down side to a single is they are a little touchy meaning light throttle movements mean you gain more rpm faster but I personally like this and don't find it a problem at all and only noticed between 1-2k rpm.

High octane even fitted a 90mm tb and plenum to there r34 gtr twin turbo track car, now why would they have done that if multis are better and hypertune would have supplied them what ever they wanted?
 
#8 ·
Matt I spoke to pete at hypertune about multi tb and single and he said he would remove the restrictive multi tb on any rb26 over 400hp now hypertune are classed as the best in the business all over the world. Considering the sell multi tb plenums and singles do you think the have a reason to talk people into singles?
Being serious here and not intended as a dig at all but as they're far cheaper to manufacture, I presume profit margins are greater and a good sales pitch.

That backed up with what amt have shown in flow charts should be enough to convince any one.
What dimensions; stock against 90mm, 100mm etc?

Last year I had multis now I have a single bearing in mind mine is 100mm so more focused on drag than circuit/road. What I can tell you is my engine now naturally revs ALOT faster I don't mean high rpm I mean from 1k rpm onwards.
You mean you have a less linear throttle control and it feels like it revs faster?
You actually have more lag but coarser control, as I see it.

The down side to a single is they are a little touchy meaning light throttle movements mean you gain more rpm faster but I personally like this and don't find it a problem at all and only noticed between 1-2k rpm.
You've just answered the question above.

High octane even fitted a 90mm tb and plenum to there r34 gtr twin turbo track car, now why would they have done that if multis are better and hypertune would have supplied them what ever they wanted?
I don't know the car Dan but I can think of several reason just off the top of my head why you would do it to a track car and not road car;
Weight
Mechanical complexity
Throttle control
Cost

The question you omitted is; at what point do the standard TBs become restrictive to warrant changing?
 
#9 ·
Easiest way to find out is to take a highly modded engine and run it up on ITB's then swap over to a single and get some figures in that config.

With a bit of decent data logging you could quite easily get conclusive results...



TT
 
#12 · (Edited)
Similar discussion here talking about the benefits of multiple throttle bodies.

Personally I would stick to throttle bodies the benefits mentioned above suits what I look for in the way my RB engine drives on the road.

Saying that on my Formula Renault it has a single 65mm iirc throttle body. Two different engines so no comparison but it is fed with fresh air from the scoop and then down through the plenum through the air filter and into the engine. As far as response goes it's pretty crap low down and only and we always keep to the power band from around 4800-7250rpm. As far as I can remember F3 uses throttle bodies but totally different engine and concept as these are spec race engines.
 

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#15 ·
The main reason I went to single plenum is I wanted to free up some power and if it ment I could run a smaller turbo to get the power I wanted easier then I would gain more response. Hence why I have got a 67mm turbo, as you no Matt dyno numbers don't mean much there's so many fake numbers there's no way cars performance can be compared on a sheet of paper. The only way is time weather it be a 30-130 time or 1/4 mile
 
#18 ·
Matt your asking me questions I don't no and don't need to no.

All I'm doing is giving you reasons why I chose a single tb, why don't you give hypertune a email tell them your aiming for 1300bhp and ask them what they reccomend I'm sure they will be able to answer all your questions.

Hypertune said multi tb become very restrictive at 400hp.

Rich at amt had 750bhp at the flywheel and crap old road tyres he also had 19" wheels.

Considering I have 50hp more and better tyres if say I'd be a low 10 high 9.peak power doesn't mean a great deal Matt its the area under the curve what makes a car fast.

I'm going to do a Santa pod trip and run my car see what it does
 
#21 ·
Matt your asking me questions I don't no and don't need to no.
Dan, I'm asking you questions because you've said that a single TB is better than multiple TBs. You have said in the past that you don't believe my car makes the claimed power and one reason is because the ITBs are restrictive. I'm asking you to prove that they are causing a restriction because, as in the simplest of terms, I'm not seeing it?

All I'm doing is giving you reasons why I chose a single tb, why don't you give hypertune a email tell them your aiming for 1300bhp and ask them what they reccomend I'm sure they will be able to answer all your questions.
I don't need to Dan, the dyno and road tell us everything we need to now about the efficiency of the engine and where the restrictions are.
Why do you need to run 2 bar of boost on your car, why doesn't it make the power at 1.5 to 1.7 bar?

Hypertune said multi tb become very restrictive at 400hp.
On what Plenum and against what size single TB?

Rich at amt had 750bhp at the flywheel and crap old road tyres he also had 19" wheels.
Sorry but I disagree, unless he's somehow managed to overcome physics, which I doubt. I don't understand how every car at TOTB ran the terminals for their power yet Rich managed to run considerably faster; his car was either lighter or he had more power IMHO.

Considering I have 50hp more and better tyres if say I'd be a low 10 high 9.peak power doesn't mean a great deal Matt its the area under the curve what makes a car fast.
You should be in the 9s on your first outing then. What bearing does area under the curve have if you're constantly above 7krpm?

I'm going to do a Santa pod trip and run my car see what it does
By your own logic, you should run 9.8 at 137mph Dan.
 
#19 · (Edited)
I am not convinced that the single offers any more benefit the inlet to the std plenum is what 80mm? that volume of air that can enter and always have a constant pressure regardless of what level of opening is on the ITB. On a single your still feeding through an 80mm pipe into 90mm throttle which then controls the air in through the plenum and into the cylinders if anything I can only see disadvantages and none of the advantages unless there is some proper data from the same engine with just those two differences ITB and a Single plenty setup.

I will be going down the Nismo plenum route at some point in my search for optimisation and get rid of the issues with the Oem plenum air flow design.

I think those who say single throttle is better is based on their own personal opinions and views. Would have been far cheaper for Nissan to have carried over a single plenum from the RB25 no? They clearly saw a benefit. In the after market work it would be far more expensive to develop a improved design or even larger ITB setup so people come out with a single which is easier and cheaper and something they can sell.
 
#20 · (Edited)
I am not convinced that the single offers any more benefit the inlet to the std plenum is what 80mm? that volume of air that can enter and always have a constant pressure regardless of what level of opening is on the ITB. One a single you still feeding through an 80mm pipe into 90mm throttle which then controls the air in through the plenum and into the cylinders if anything I can only see disadvantages and none of the advantages unless there is some proper data from the same engine with just those two differences ITB and a Single plenty setup.

I will be going down the Nismo plenum route at some point in my search for optimisation and get rid of the issues with the Oem plenum air flow design.

I think those who say single throttle is better is based on their own personal opinions and views. Would have been far cheaper for Nissan to have carried over a single plenum from the RB25 no? They clearly saw a benefit. In the after market work it would be far more expensive to develop a improved design or even larger ITB setup.

Your forgetting that every cylinder isn't drawing 100% air at all times. Why don't you email the like of hypertune tell them there wrong I'm sure your theory would mean a lot to them. You havnt mentioned anything about the flow drop you get with itbs on the rb26 if this wasn't the case then yes it would be pointless removing the itb but it does that's why they need to be removed.


Come on people don't you think hypertune no everything about making plenums for the rb26 all there doing is advising people the best way they have seen to work
 
#28 ·
Indeed, I thought the question was are ITBs or singles better...

Most of this is saying that if you have a bigger throttle area, you will get more air into the engine (regardless of how many throttle openings, the total xsec area), which is obvious :)
 
#30 ·
Your engine has done well matt either way, unless any one has done a true back to back on multi v single tb who knows for sure. I would be very surprised if hypertune was wrong tbh.

The drivebility isn't much diffrent matt the main differences is only between 1-2k rpm mainly or that's what I have found with mine, and that's with mine running a 100mm tb what hypertune don't reccomend for road cars so I'd imagine drivebility would be quite simular from a 90 to multi.

Cossie04 also went from multi to single tb and said there's was no real diffrence.
 
#34 ·
Your engine has done well matt either way, unless any one has done a true back to back on multi v single tb who knows for sure. I would be very surprised if hypertune was wrong tbh.
I'm not saying Hypertune is wrong Dan, what I'm saying is, as yet, I've not found the ITBs to be restrictive. My engine hasn't missed a beat since it was first run in back in 2010. Granted it hasn't done high mileage but it's been given plenty of stick.

The drivebility isn't much diffrent matt the main differences is only between 1-2k rpm mainly or that's what I have found with mine, and that's with mine running a 100mm tb what hypertune don't reccomend for road cars so I'd imagine drivebility would be quite simular from a 90 to multi.
I honestly believe that it's actually you who can't tell the difference in the drivability Dan, that's not meant to sound as a dig or disrespectful but the non-linear control of the butterfly has already led you to believe that you're revving faster just be changing to a single TB. In other words, you're just subconsciously adjusting your driving to match the new control characteristics of a big single butterfly.
 
#33 ·
The thing what surprises me so much matt is that it's all to do with flow and when a flow specialist has flow tested theulti tbf and said they drop to much flow to be worth having this isn't good enough for you.

If the itb were on sliders when open there is nothing left in the port then yes they would be the best option but they don't the leave a shaft stuck right in the middle of the flow of the air.
 
#35 ·
The thing what surprises me so much matt is that it's all to do with flow and when a flow specialist has flow tested theulti tbf and said they drop to much flow to be worth having this isn't good enough for you.
I've never said it's not good enough for me Dan. What I've continued to say all along is that I'm not experiencing the losses that are being claimed, had I reached a point whereby the ITBs were the restriction, I would have changed them. I believe in your application, you're actually having the opposite effect on your car as it's not a drag car and you won't see any benefit, in fact, I'd say you were actually experiencing losses over ITBs.

If the itb were on sliders when open there is nothing left in the port then yes they would be the best option but they don't the leave a shaft stuck right in the middle of the flow of the air.
Indeed, it is a very valid point Dan and I concede that at some point through the performance characteristics, a correctly sized single will ultimately flow more air than ITBs. What you're not conceding or answering is the point at which that cross over becomes valid.
 
#36 ·
Matt I no the diffrence in drivebility my plenum has caused but mine is not exactly designed for drivebility as its hypertunes biggest plenum and it still drives ok.

Yes I uderstand what your saying you havnt come across the restriction of itb and I'm very surprised from what I've been told.

There's no way me or you could ever no the answers to them questions unless we spent silly amounts of time and money tested what we both ain't preperred to do.

The only person on the forum who done some what a back to back was smart dj he gain around 70bhp going from a stock plenum to a rips single tb plenum all done by abbey motorsport at the same boost.

That backed up with what amt showed/explained to me and hypertunes said was enough to make me decide a single tb was the way to go.
 
#37 ·
Matt I no the diffrence in drivebility my plenum has caused but mine is not exactly designed for drivebility as its hypertunes biggest plenum and it still drives ok.
Plenum? I'm not questioning the plenum Dan.

Yes I uderstand what your saying you havnt come across the restriction of itb and I'm very surprised from what I've been told.
That's the point I'm making Dan, I appreciate you value highly what you are being told and I respect that mate, that is said sincerely. I'm just not seeing the restriction as yet so at what point does it become beneficial to change over?

There's no way me or you could ever no the answers to them questions unless we spent silly amounts of time and money tested what we both ain't preperred to do.
If I hadn't of already changed to DBW, I would have happily tested back to back but now it's not so easy to do sadly. I wonder if I can persuade Bob to test B2B, that would be a fair comparison wouldn't you agree?

The only person on the forum who done some what a back to back was smart dj he gain around 70bhp going from a stock plenum to a rips single tb plenum all done by abbey motorsport at the same boost.
This is where I honestly think you're getting a little confused Dan. There are huge gains to be had by running a different Plenum design; standard/nismo/greddy/RIPS/Hypertune all have different designs and characteristics. That is not what is being questioned though.

That backed up with what amt showed/explained to me and hypertunes said was enough to make me decide a single tb was the way to go.
Indeed, of course it was going to be better Dan but better than what as now you're adding the Plenum design into the mix. I honestly believe that a single TB is overkill for a road car and the marginal gains will only be apparent on a drag application where it spends most of it's time at or near WOT, would you not agree?
 
#52 · (Edited)
Are those results with the same Plenum and the only change was standard ITB's to what size TB?

Edit: Looks like a comparison between with and without ITBs to me, just to show what the restriction is; i.e. not a comparison against a single TB which has it's own restrictions?
 
#53 ·
That was with and without I also read somewhere Amt saying a single tb lost only a couple of cfm but obv that wasn't on that test. That's just showing how restrictive the itb are. But we went through all this last time matt. I've given you all the information I no or should I say researched
 
#55 ·
Is it not that the distance from the TB to the valve is important?
As is the distance from the valve to the plenum?
Aslo the volume of the plenum plays are part. There are many variables and I'd thing that Nissan have done the developement work on this and by bolting in an 'uprated' parts and saying 'look, more power' does not actually tell the whole story.
A dyno gives very little indication of engine responce which is very important for getting the best from a race engine.
Maybe the willy waving is more important here, BTW I run 6 TBs now and I'm very happy with the performance and I see no performance gains with a single.
I have run a Q45 on my old RB30 but that was for simplicity reasons.
 
#59 ·
I would have to say the reason Hypertune say the 6 throttle is a restriction past 400hp is that they make an expensive single throttle body to go with their plenum.....but none for the 6 throttle version.....just marketing.

.....have they got flow bench charts between their two plenums showing this fact???
 
#60 · (Edited)
I'm sure they have Chris il email them to see if they have, high octane built there r32 with a hypertune multi tb plenum then when they built there 34 they went with a 90mm single and stuck with it that must be for a reason otherwise they would go back to multi.

What the reason rips use singles on more less all there builds to Chris?
 
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