I put on my Lonewolf intake, and 90mm TB

[big-phil]

Baby blue Gallardo pwned for showing off!

yeah I didn't want that to be me:)

[Spooler]

Funny, after that introduction to the " I am at 6:10 min. in I figured you would be on it a little harder......LOL At the end I saw why, the old blue light special.

[big-phil]

Funny, after that introduction to the " I am at 6:10 min. in I figured you would be on it a little harder......LOL At the end I saw why, the old blue light special.

Oh yeah, the Police were parked at the exit just waiting for someone! I thought i did too much

[bradyzq]

Hey Brady,

 

The pressures were all done in gauge, that is usually how they are discussed, nobody talks that their NA engine is running at one bar without a turbo !! This is why the I used Bar-gauge not Bar-Absolute.

 

When you run the triple carbs you essentially have an ITB per cylinder, therefore each cylinder is using the 45mm plate all to itself. So in order to compare I would have to use something relative such as when the L-6 is on the intake stroke, so two cylinders are filling, not all 6 ( though that would be amusing ....once). That is what I was thinking. All the air the engine will ever get has to pass through the 90mm, as opposed to each 45mm. Even if its spinning to 10-million rpm, it will be filling only two cylinders at once, assuming its using the standard straight 6 firing order...

 

 

Cheers

 

Chris

 

Hi Chris/All,

 

I stand by my absolute vs. gauge pressure position on this one. To clarify a bit, consider your example at 15psi (1bar boost) instead of 22psi:

 

Just thinking out loud, if a Q45 displaces 4.5 liters per full firing sequence at one bar, and the L series 2.8l at one bar, doesn't that mean that a boosted L series has a much similar air demand as the q45 for example 2.8 l x 1.5 bar ( 22 psi) = 4.2l ? This is assuming A Im somewhat on the right track and two the boys at nissan did use a 90mm TB on the q45 for a reason...

 

I think I might be getting mixed up I was using some of the really simple compressor calculations we use in commercial diving.

 

According to your math (2.8L x 1.0 bar ( 15 psi) = 2.8L), a 2.8L boosting 1bar would ingest the same mass of air as a NA 2.8L, which is not the case. It should be equivalent to a 5.6L. Using absolute pressures solves this contradiction.

 

Regarding the firing order (1-5-3-6-2-4), there are not 2 cylinders doing the same thing at the same time. Yes, for example, cylinders 1 and 6 will both move up and down together but they are not on the same stroke. For example, 1 will be on the intake stroke (down) while 6 will be on the power stroke (also down). Obviously only number 1 will have an intake valve open to admit air. In that respect, there is only 1 cylinder beginning its intake stroke at any given time.

 

However, due to camshaft duration, that intake valve may be open for quite awhile, during which time, cylinder 5 and maybe even cylinder 3 may begin ingesting air. So, in THAT respect, there are effectively at least 2 cylinders somewhere in their intake strokes at any given time on our L6s.

[WizardBlack]

I'm still on the air velocity thing. The air has to be slow enough as it enters the plenum (and of the right direction) to easily make the turn to cylinder 1. This is done by design of the plenum size, runner size/taper/design, intended engine performance (rpm, displacement, rod/stroke, valves, cam timing/lift), intercooler piping size and direction, etc.). It also has to evenly distribute to all 6 as well. The only way to know for sure is to do a fluid analysis on the whole shebang.

The more air you are flowing through a throttle, the higher it's velocity will be. This is going to change how it distributes to the cylinders. Keeping the velocity down when massively raising power levels (for the given engine parameters; including plenum) should help keep it more even, but it's not a perfect solution.

The whole point of it is to keep flow even. When it isn't, your A/F ratio is varied amongst cylinders. Some will be hotter than others. Some will be too rich while others are close to detonation. It basically makes your engine demonstrate a lower output before being limited by detonation or heat, etc. There are very few manifolds that are going to be perfect. That's why high end standalones allow for cylinder-to-cylinder fuel correction. I guarantee you that any top level racing engine has already had it's flow balance tested and adjusted for (note that I didn't say corrected). Likewise with high end sports car engines. They do as much design as they can and then they tune for what's left.

I know, Tony, that you are stuck like a dog with a bone on that puppy ( and just to be clear, I mean that in a friendly tone ) and that's fine. No one has fluid flow analysis to answer you and you know they don't, so you won't get the level of tech data you want to be satisfied, methinks. The bottom line, IMHO, is that it is better to be too big than too small and aggravate the balance issues.

I have personally owned a car (Evo 8) with a massive throttle on an even smaller engine. The throttle spring was so soft you could practically breathe on it and it would open. Add to that an HKS twin plate that left the clutch pedal feeling like a normal throttle pedal does. It took a bit to adjust to, but was not an issue after adapting. Who ever said big turbo cars had linear throttle response anyways? I base my power control off of boost pressure and sound (which is the same thing, really). Big turbos have too much transient response at low rpm and throttle levels to do otherwise.

To directly answer Phil (after first apologizing for co-hijacking the thread), you would need per-cylinder EGT readouts or somehow gaining cylinder pressure numbers or A/F ratio numbers on a real world car. I've seen per-cylinder EGT readout on some street cars before. The next best thing would be to do dyno testing with one EGT gauge and doing back to back pulls with the probe in each runner, but everything else has to be amazingly equal. You'd be best off with a Dynapack style dyno to do that. I used to own a 4WD dynapack and it was precise enough that it could demonstrate repeatable power differences with A/C on vs. off.

[Tony D]

Correct me if Im wrong, and this is just based on area calculations, If the RB26dett had 6 butterflys, then each one caters to an individual cylinder. Therefore during each intake stroke the cylinder has roughly 1590 square mm's to play with(3.14x22.5 squared). With a 90mm TB you have a much greater area, however it is divided by two, as you have two cylinders drawing air at once (3.14x45 squared divided by 2). It comes out to roughly 3150 mm square per cylinder...

Back to the same argument Tony is using, nobody has given a good reason as to why there is a crusade against large throttlebodies and not other forms of mis-engineering ?

Cheers

 

Chris

 

Flowing down a runner with 1590 sq mm of cross sectional area.

 

Following my line of though now, are we? My point exactly...

 

Though rate-of-change in the runner since the TB is closer to the intake valve is more abrupt. In this case a 'larger' plate with the plenum to act as a buffer and soften throttle response may make a high horsepower car easier to modulate.

 

You are talking about flow of one cylinder through the big plate, but the runner is only so big. And if you have a plenum that is pressurized opening the six 1590 sq cm TB's will have pressurized air coming in quickly. A larger body may be required to repressurize a plenum which has been evacuated to 'negative' pressure on a drop-throttle event. Which points me towards drag racing application.

 

Again, this is not a 'we use a small body' argument---some people may be justifying if for whatever reason, but I'd like a reason why it's necessary. I don't know that it is, and rational reviewing of 1000 hp cars makes me question why? I'm not on a large-body 'crusade' or anything of the sort, I want to know what it does, why the choice was made. As a 'crusade' about form of 'mis-engineering'...well...I mean, I wasn't aware this had turned into a ricer bling site where you put a fart can on the back of the car purely for appearances, along with a lot of stickers and learning some jargon to throw around there. I thought this site was more, about quantifying the performance, about learning the whys and not just another Honda trick-out parts site.

 

If there is a functionally rationalized reason for a given part being on the car, then it's not 'mis-engineered'---if there is no functional purpose for a given part being on a given car, it simply isn't engineered at all! Mis-Engineered implys that someone did something because of a mistake. That is a far cry from someone saying 'it looks badarsed and so I put it on there'---that's not engineering, that's accessorizing. Please read where I posted 'because I can' is all the justification I fell anybody needs to give for anything on their car. There is nothing wrong with 'accessorizing' a vehicle as you see fit. Just don't call it "Engineered to be Feared"! It's a whole different dogma when you get into the 'Accessorized to be Feared' mindset.

[Tony D]

sorry have not been on. The 90mm TB is over kill, so is the 3" IC pipe, and 4" exhaust.

 

I don't know that the 4" exhaust is 'overkill' on a car running a GT35R at it's horsepower limits. It was not uncommon in Japan to see 125mm piping on turbo cars as a matter of course. Today they still sell 104mm piping for S30 Turbo setups.

 

Testing on JeffP's car says that his 3" exhaust may well start to be a sticking point on horsepower development from this point forward.

 

The guys at E-Motive said 4" minimum...

[Tony D]

I know, Tony, that you are stuck like a dog with a bone on that puppy ( and just to be clear, I mean that in a friendly tone ) and that's fine. No one has fluid flow analysis to answer you and you know they don't, so you won't get the level of tech data you want to be satisfied, methinks.

 

Actually, that's not true at all, several members have access to CFD modeling, and have posted results of it. Which is why I mentioned it, this should be a good way of solving the problem...

 

I know people want to argue about what is 'best', but from the beginning I have simply asked 'why'? You have given a theory, it's possible that's it. I have also given several rationalizations as to why a larger body would be used. But the predominant 'bigger is better' paradigm just seems like so much B.S. for most of the vehicles out there. Like I said before, this seems like the EFI equivalent of putting an 1100 Holley Dominator from your 426 Hemi Dragster on your 318 Dodge Dart and smiling broadly. Some of Phils comments seem to support that, as well.

 

Now, let me restate it again in case anybody has missed it:

I am building a Bonneville Engine which will be at WOT for extended periods and not have to worry about Modulation Issues. If someone can give me a good reason to use a big single as opposed to triple ITB's on the manifold, it would make plumbing the setup much easier.

 

Everybody is getting caught up in wanting to argue this side of the point or the other, when all I'm doing is asking for concrete data which may support which way I should go on a highly stressed engine in those operations. You know, engineering a solution, instead of guessing, or accessorizing. My Bonneville Car is not a place for advertisements or accessorizing, it's for functional things to do one thing: break a record. Looks are nice, but from my personal experience a lot of things that are touted as 'bigger and better' rarely are, and you functionally get far more payback performancewise from things you never thought would work as well as they did. I can bet there are people on the street running a cam with more lift and more duration than our current record-setting Bonneville N/A engine. Think about that for a second...

 

Likely what we will end up having to do is (like everything else) build BOTH setups at great cost, and then do the dyno testing ourselves. (The comment Spork Made has me interested...that 'larger than normal runners...may end up buying a similar manifold, and then testing various bodies on it.)

 

Now, that being said, if I put up a couple grand in Dyno Time and parts procurement costs (well, the triples setup was $2K+ and we haven't made the MonZter Plenum Knock-Off yet...) believe me I will likely not be tooo forthcoming with the information. I might get a bit more arrogant, and THEN start to argue based on my personal testing... but to that point I'm just asking for an engineering analysis.

 

I think the CFD owners got more things to do than run simulations on various throttle body sizes... but it sure would be nice if one of them runs across this thread and offers to 'put the argument to rest' like what happened on the plenum thread MonZter did!

 

Yes, and apologies to Phil for jackiong his thread...

[Canadianz]

This is getting interesting !!

 

First off, sorry for hijacking the thread, I'm going to continue the rest on via PM or on the large TB thread after this post. The car is looking good Phil !

 

So far, I am on board with a 90mm being able to flow a ton more, its just alot bigger, this makes sense to me. I agree with you that it may be waaay too much!

 

Last night I played with some HP and throttle plate calculators Here and Here . Interestingly the second seemed to show a "HP Loss" when too small of a TB was used, When I switched from an engine of 2.5L with 15psi of boost 7000 rpm redline and a 90mm to the same engine with a 56 mm TB it showed a loss of 4 hp. Play with the calculator a bit see if its on the ball or not. It may be off... There must be something going on with TB sizing.

 

I know some small 4's like the b16 in hondas have stock a 56 mm TB ... compare that to some of the high hp cars here only running the 60mm tb's or that ball park. Are the honda's tb's too big factory? The s2000 engine uses a 62 mm TB and we know it to be one of the higher hp/L N/A engines of today ...however when they increased the displacement the TB size went down to 60 when they added 200 cc's ! This is confusing stuff.. If its just for tip in response, wouldn't a cam on the pully be cheaper ?

 

If they do still sell 103 mm piping in Japan, that doesn't mean anything at all, they also sell Bozuku style tail pipes in JDM land too, hardly functional. Lets just assume though that the 103mm piping has a use on a high HP car, then is there a negative to stepping down to say a 60mm TB, if the entire intake and exhaust tract is around 3 inches ? Would this impeded flow ?

 

Next up the "why necessary argument" I see where your comming from, don't put a performance part on something on just for looks, which is all fine and dandy, as we are trying to stay away from the ricer image. This is good ! I agree here too. What I don't agree with is that the 90mm throttle body becomes such a heated topic, when I see some other builds with totally useless installations, that take less heat. For example even improperly designed cages on hybridz usually take less heat than this topic, or ideas that totally don't make any sense, eg Flared cars with inner fenders intact, intercoolers sitting on top of the engine, with no ducting ! ! Those are my ideas of rice !

 

Again I am not saying that a 90mm TB is the best mod you can do on a car or that it is even necessary. I am interested to find out if anyone has any real back to back data on what it effects. The only real world I have is from my car and driveability, which there is little to no effect. Tony is using the logic that someone should prove him that it is useful, as his first hand experience is that it is unnecessary. I will take the other side and say there is no negative from my experience so why not ? Innocent until proven guilty or guilty until proven innocent ! ?

 

Cheers

 

and Ill get off your thread Phil !

 

Chris Crombie

[Tony D]

AHA!

The Honda TB's (as most nissans) are say 500CC a cylinder. Didn't the Z31 have a 55mm tb, and the VG30DETT have dual 50's or 55's ?

 

The s2000 went down in size? It's a long stroke motor that revs higher than most of the street stuff out there... cam on the pulley does some stuff, but what are you asking about since they dropped the diameter? Looks like something is at play there. But remember we are talking TURBO here as well, I don't know of any OEM Turbo or forced induction S2000's...

 

Cylinder sizing may be part of the equation.

 

But you are showing 'peak' hp of only 4hp lost. I have seen similar numbers on dynos where you pick UP 20 hp due to whatever reason lower in the powerband.

 

This is what I was getting at, maybe this is a 'drag racing' part, and give s you 'peak' power, but there is a midrange sacrifice. Without dyno testing, it iwll be hard to quantify, though.

 

Bozoku pipes are not the same as running a 475 RW KW car around. Please give me credit for not making outlandishly stupid comments. If someone wanted to put Bozoku pipes on their car, I would not have a problem with it. But someone with 475 kw to the rear wheels (you do the conversion) kinda tells me they have a reason for it being there. Especially now that I can see 658HP on a 3" pipe may be a practical limit. And again, if the guys at E-Motive tell me 'use at least a 4" on this horsepower level' I'm figuring they're not Bozuku fans... You appear to make a link between the inlet size and outlet size orifices, which I can only figure is a joke, I won' t even try to explain how wrong that is on so many levels. Frankly for Turbochargers, NO exhaust is the best exhaust, and that has been proven in several dyno runs by severl independent indicviduals. So no, I don't think a 4" exhaust is overkill. a 3" exhaust on a BONE STOCK ZXT returned 20HP gain with no drop on the bottom end. For Phil's car, I have no doubt the 4" is being utilized, and there is not a chance it's restricting the output on the top end. A 3" pipe on the other hand, as he approaches 600HP to the rear wheels may start being the lower limit of acceptable sizing.

 

You seem to be confusing questioning why with criticizim. It's not, it's asking for a reason. If you think a guy saying all the American Roll Cages are constructed out of 'steam pipe' and consider that a mild form of heat, I don't see anybody going that far at all. Not even JeffP in his statement. I dont' see any 'heat' just some guys asking why, and what has anybody quantified. As stated before, this isn't 'Accessorize to be Feared' website. Rest assured there is plenty of stuff to criticize with the roll cages because it's a more defined art with more people familiar with it, and given examples that work and what don't. Not so much with TB's...and then there are those that will defend something when it's not under attack.

 

If I want to criticize work, there's plenty places to do that. I come here to LEARN, and I asked WHY. Can you get it though your head this is NOT criticizim, it's asking for REASONS... some shred of empirical evidence outside of 'it looks badarse' to put one on MY PROJECT.

 

I'll repeat it for the last time, as apparently nobody has the answers: I'll likely buck up megabucks and run testing to see what works. But I'd prefer not to have to buy 6 throttle bodies and run tests on them all. I'd like to get a ballpark figure to maximize my tuning time on the dyno and help narrow the selection quite a bit.

 

The day I make 750HP with a 60mm (or 70mm) throttle body, I will be the first guy to necropost this thread and post a 'NOT NEEDED TOTAL WASTE OF MONEY: IT'S A BLING BLING THING' criticism.

 

Till that point, I'm ASKING. Nobody has an answer save for Wizard Black.

[Tony D]

Tony is using the logic that someone should prove him that it is useful, as his first hand experience is that it is unnecessary. I will take the other side and say there is no negative from my experience so why not ?

 

I just read this, and if this hasn't taken a Z Car.com twist I don't know what has, I'm off this thread.

I never said a GD thing like that. How someone can make that statement after what I wrote is beyond my comprehension, and frankly I'm disapointed that it comes up here. Terribly disapointed.

[letitsnow]

I think the CFD owners got more things to do than run simulations on various throttle body sizes... but it sure would be nice if one of them runs across this thread and offers to 'put the argument to rest' like what happened on the plenum thread MonZter did!

 

Yes, and apologies to Phil for jackiong his thread...

 

I've got solidworks 09(student) and cosmos, if you can agree on a design and test parameters, I can do some basic CFD. I'd prefer the model to be simple, like a 3" tube plenum with straight runners.

[BRAAP]

I've got solidworks 09(student) and cosmos, if you can agree on a design and test parameters, I can do some basic CFD. I'd prefer the model to be simple, like a 3" tube plenum with straight runners.

 

Unless the CFD can simulate the air flow, pressure waves, and overall fluid dynamics of the air mass from opening and closing valves due to piston movement, (taking into account valve timing in relation to piston motion during valve opening/closing), at various RPMs as it enters, transitions, and stirs about pre, and post TB, the CFD display and computations will be approx 90%-100% useless.

 

Sorry, not trying to discount the abilties of CFD, but in the application of an Otto cycle engine, unless it can simluate the dynamics of the air mass as the engine sees it, helmholtz, etc, static air flow info is only barely partially valuable in finding that answer.

[letitsnow]

I agree, to a point. As far as determining overall performance from a theoretical point of view, you need way more math than just flow numbers. We're currently concerned with the throttle, which is separated from the source of pulsing(intake valves) by a plenum. The plenum has an effect of smoothing out the pulses significantly, it's possible to calculate how much, but I couldn't do it, I know how the math works, but I don't know the details on actually doing it. I've been thinking of getting an sae paper specifically about calculating intake resonance, apparently helmholtz is a rather rough approximation at higher engine speeds.

[Bernardd]

run testing to see what works. But I'd prefer not to have to buy 6 throttle bodies and run tests on them all. I'd like to get a ballpark figure to maximize my tuning time on the dyno and help narrow the selection quite a bit.

 

The day I make 750HP with a 60mm (or 70mm) throttle body, I will be the first guy to necropost this thread and post a 'NOT NEEDED TOTAL WASTE OF MONEY: IT'S A BLING BLING THING' criticism.

 

Till that point, I'm ASKING. Nobody has an answer save for Wizard Black.

 

Tony, here's a link to a 692rwhp KA24 with a 60mm tb

 

http://www.ka-t.org/forums/viewtopic.php?t=45343

[big-phil]

man you guys are really going over my head. I'm glad to hear the 4in exhaust might be in my favor. As for the 90mm TB I'm stuck with that, and the intake. I just bought another 38mm WG, a Tial. I'm going to replace my Turbonetics 38mm to see if thats whay I can't control the boost. If not I'm going to mount one WG to the left of the turbo on the manifold plus run the other were it is now. Yup two WG's. Its cheaper for now than buying a BIG single. I got this other WG local.

 

Thats my sticking point as of now. I can't stop the boost from climbing.

[bradyzq]

Have you tried increasing the gain on the Profec boost controller? It can smooth out the boost curve.

 

The Profecs are usually pretty good.

 

Job 1: get boost approximately where you want it after it's spooled. (adjust duty cycle)

 

Job 2: make boost curve flat. (adjust gain)

 

Job 3: get boost to correct level readjust duty cycle)

[big-phil]

Have you tried increasing the gain on the Profec boost controller? It can smooth out the boost curve.

 

The Profecs are usually pretty good.

 

Job 1: get boost approximately where you want it after it's spooled. (adjust duty cycle)

 

Job 2: make boost curve flat. (adjust gain)

 

Job 3: get boost to correct level readjust duty cycle)

man i've done everything to the controller, the wastegate. I just think its as simple as my wastegate is in a poor place, and is being out flowed. If the 2 work I might in the future buy a big single and place it on my other manifold in a better location.

[kiwi303]

Unless the CFD can simulate the air flow, pressure waves, and overall fluid dynamics of the air mass from opening and closing valves due to piston movement, (taking into account valve timing in relation to piston motion during valve opening/closing), at various RPMs as it enters, transitions, and stirs about pre, and post TB, the CFD display and computations will be approx 90%-100% useless.

 

Sorry, not trying to discount the abilties of CFD, but in the application of an Otto cycle engine, unless it can simluate the dynamics of the air mass as the engine sees it, helmholtz, etc, static air flow info is only barely partially valuable in finding that answer.

 

Barely Partially is on the other hand, a START.

 

Reading through this thread, while a lot of it is over my head, I have a few questions... as far as lower velocity, higher volume vs higher velocity lower volume piping and throttle bodies goes, would not a expansion chamber between the smaller throttle body and the plenum entrance have the same effect as the larger throttle body AT the entrance? providing the air space to expand and slow before entering the plentum...

 

The following MS paint sketch is pretty basic, but it shows what I mean (I hope).

 

 

Notice plenum 1 has a large IC pipe and a large TB, both matching the entrance to the plenum. while Plenum 2 has a small IC pipe and small TB, but has a expansion pipe grading up from the IC size to plenum entrance size.

 

given all the debate about TB sizes, what seems to me to make more effect on plenum and runner efficiency is the avoidance of sharp edges between plenum entrance and walls. Either 1 or 2 would be likely as I follow the flow arguments, to be vastly better than plenum design 4 below which would be afflicted by undesired turbulence where the air flow enters the suddenly much larger space of the plenum?

 

 

But what about a plain cylindrical plenum where the throttle body is of equal diameter as the plenum itself? (3) would there be any benefit to such a design as that?

[WizardBlack]

Barely Partially is on the other hand, a START.

 

Reading through this thread, while a lot of it is over my head, I have a few questions... as far as lower velocity, higher volume vs higher velocity lower volume piping and throttle bodies goes, would not a expansion chamber between the smaller throttle body and the plenum entrance have the same effect as the larger throttle body AT the entrance? providing the air space to expand and slow before entering the plentum...

 

The following MS paint sketch is pretty basic, but it shows what I mean (I hope).

 

 

Notice plenum 1 has a large IC pipe and a large TB, both matching the entrance to the plenum. while Plenum 2 has a small IC pipe and small TB, but has a expansion pipe grading up from the IC size to plenum entrance size.

 

given all the debate about TB sizes, what seems to me to make more effect on plenum and runner efficiency is the avoidance of sharp edges between plenum entrance and walls. Either 1 or 2 would be likely as I follow the flow arguments, to be vastly better than plenum design 4 below which would be afflicted by undesired turbulence where the air flow enters the suddenly much larger space of the plenum?

 

 

But what about a plain cylindrical plenum where the throttle body is of equal diameter as the plenum itself? (3) would there be any benefit to such a design as that?

Yup, that's what I mean. If you had a JUN style manifold like 1 or 2, it is not as important. With the style posted here, you'd have a choice between 3 and 4. Note that the VH45DE also has a throttle flange pretty close to the plenum, so they do that as well. Of course, the entire intake tract is fat on that thing.

Then again, as BRAAP and a few others mentioned, there are lots of things on the engine you are bolting the stupid thing to that will toss all your calcs out the door.