boosted hybrid

Lately this site has become a bit boring in terms of technical threads. I am trying my hardest to get tech articles done for my website, and post them on here. Here is the my concept: Indivdual throttle bodies, d16 and boost.

A little background. Honda is a car manufactuer and a motorcycle manufactuer as every one knows. With the motorcycles turning to fuel injection instead of carburetion, tech same technology on cars appears on bikes. Honda is a company that likes to standardize many of the same components, including sensors, injectors, etc that they use on the automobile engines. With the introduction of the Honda CBR 929 RR honda utilized many trick components. One very trick item that Honda encorporated into the 929 RR's design was factory individual throttle bodies with TPS, fuel injectors, fuel rail, fpr that they used on our honda engines.

Here is a shot of the itb's:



Factory TPS sensor:



Factory injector/injector clip:



Factory fuel rail/fpr:



The d-series heads look like they were meant to have these itb's mounted onto them. The I.D of the throttle body matches the port perfectly. Each throttle body is proportioned with each port, so that they match up like they were designed for the d-series head. Another aspect of the CBR ITB's is that they utilize a 42mm throttle body for each port. With the standard/conventional single throttle body system you can go to large of a throttle body for your engine displacement. They car cause you to lose low end throttle response, but more importantly net little to no gains. The 42mm size of each throttle body is optimal to the port size/flow capabilities of the d16 head.

Look how closely the itb's mount up to the d16 head:


Now my theory behind individual throttle bodies on a forced induction car. Individual throttle bodies create the head to flow much more cfm per throttle position of a normal single throttle system. Each runner of the intake ports is getting its own source of air flow, therefore getting crammed with the maximum amount of air at various vacuum and boost levels. Super large plenum of manifolds such as GE or Victor X no doubt flow far greater than the puny stock counterparts, but they are still restricted to the overall flow of the plenum by the single throttle body. Individual throttle bodies are used in all motor applications to squeeze the last bit of power from a tuned set-up as possible. They drastically improve midrange and high end response from the end. Taking this principal towards forced induction a few things I speculate will occur:

1. Faster spool up. The head is going to have maximum flow at vacuum, and at boost so the overall flow of the head is going to be increased. When overall flow is increased, in this case by taking out the single throttle body system the forced air can travel quicker into the combustion chamber, thereby decreasing spool up time.

2. Better throttle response from the overall system. Due to the 42mm throttle bodies per cylinder, the low-mid-high end will show gains. Low compression set-ups will have the throttle response of higher compression set-ups.

3. Drastic power increase. With the overall ability to flow, the individual throttle bodies will give power gains of 20-30whp at lower boost levels, and much much more when the boost gets turned up. The d series head are so restricted by the stock intake manifolds, that they cannot breath. Free up the velocity of the incoming air and you'll make gains, simple as that.

Now here is the tricky part. To make individual throttle bodies work with forced induction a plenum needs to be created in the same manner as single throttle body/manifolds are created. To optimize overall flow, sound wave characteristics from the head and other considerations the dimensions must be wisely choosen. I havent fully designed this aspect, so other please feel free to give suggestions.

Another aspect of making itb's work with the honda system is having the map, IAC, IAT satisfied. You need vacuum in order to do so. With convential single t-body/plenum systems you create vacuum within the plenum itself. This is where a vacuum log comes into play. The individual throttle bodies are tapped after the throttle plates on each throttle body, this is where the vacuum source is generated by the engine. To harness this vacuum for the sensors a vacuum log must be created. The size and proportion of the vacuum log is critical in order to let the stock sensors get enough vacuum to operate without throwing codes. This is another aspect of which I am designing with this system. You can see the big picture below with a sketch I made in Paint:



Its pretty self explanatory of the idea that I am trying to get across. This will benefit both hondata and AEM users since they will need to satifisy the stock sensors.

There are a few other aspects of this design that I am looking into. The first and foremost is velocity stacks for each throttle body. The velocity stacks implement the venturi effect around each throttle body. The venturi effect in a nutshell allows for the air to pass into the opening with the least amount of turbulence, much the same when you experience in an airplane. Its critical to the overall ability of the itb system to create maximum power in the plenum. I should have the prototype made very soon, and testing by late summer.

One last note I would like to add. The head as a whole is a system. If these do work as I anticipate, stock d16 heads will benefit but not as they should. The head as a whole needs to be massaged to flow with the throttle bodies. Larger valves, higher lift cam, port and polish and deshrouding the combustion chambers are all part of the final equation. The d-series can make power, but it needs to be taken to the next level in order to do so. I choose the d16 platform for my GF's build-up because I wanted to push the limits of what is percieved the be "streetable" or "doable" on a d-series engine. The goal 300whp before 12psi.

All comments are welcome. I want to keep this a technical thread.

Arturbo

Nice!

T-sohctec

Thanks for the TECH post.

Sonny

Good post, man.

It seems to me that ITB's would not benefit a boosted motor as much as an NA motor. There would be benefit no doubt, but would it be worth all of the work?

In an NA application, the intake runners are being fed via the single large throttle body and the air must make a 90 degree turn to enter each runner. Some trick engineering has gone into manifolds so that each runner can receive an equal distribution of air. In an NA application, you don't have the benefit of positive pressure to "ram" the air into the cylinder for you.

A big advantage of ITB's (that I can see) is that each cylinder is exposed to its own equal air source. The single "shared" air source is gone.

With boost though, is that still the case? It seems like it isn't. How would you equally distribute the air from the charge pipe over the 4 ITB's?

Sonny

int3gra

interesting stuff man, i miss these kinda posts from a few years ago

Licensed2Spool

Thats defnitely one of the coolest ideas Ive heard about in a long time....especially since its for a d-series engine for once.

tonesdef

Wow intresting. If i had the money i would take that idea and try and make it work cuz i've seen ITB turbo setup's on old *** celcias. But i knew there was a reason why i use to come to honda-tech and this post is why

DLOTYPER

good post, holy **** when i think about the possibilities of that!!!! damn,, but just like the guy said before it would take some crazy engineering to actually guarantee the air to flow equally from the plenum to the itb's ...good thinking though,,, absolutely mind boggling

krazyDOHC

great post ...makes me wonder...

paulzy

iTrader: (1)

I don't see a benifit to doing this over a single big plenum with 1 TB....I see waht you're trying to say, but with all the money invested in an ITB setup, you can simply turn up the boost a few pounds and won't notice a thing.

BUt if you were to incorporate a plenum for your ITB's, I see your inlet and being a problem. The location of where it is will not evenly distribute air across to the 4 TB's. I would figure a design similar to the 96+DX,LX intake manifolds would be a much nicer and smoother alternative to ditribute the air evenly...

that's jsut my take on that. But Power to you for thinking. This is how we Raise teh Bar, so go for it

romeo619romeo

kinna defeats the purpose of the ITB if you turbo

genop

This is a great idea and would make lottsa power N/A but when you go turbo and the air is pressurized, I dont think it will make much difference. Theres a reason why you dont see the people making big #'s with turbo using ITBs.

98civicEX

great post,

madmatt

Wow someone ate some smart pills this morning. Thats a really good post and an even better idea. Keep it up

prophet

jeff did a good job on the article. I believe he said the whole setup is a very quick job and the price isn't that much. Heck i'm sure if there was a demand he could produce a few of these to make a few dollars

boosted hybrid

Thanks for the compliments guys! I have been toying with this idea for awhile, ever since I saw Nissan using itb's with the R34 skyline and Sunny/Pulsar GTI-R from the factory. I have been around a sentra swapped with the pulsar gti-r and sound that the engine produced when revving was like no other I heard, this was directly due to the individual throttle bodies. The Pulsar made I believe 30-40 horespower over the sr20det engine that came in the silva's, which has to be pointing towards changes that Nissan made. I believe the individual throttle bodies had some contribution towards this.

For the plenum part, that is going to be the critical aspect of designing the whole itb/plenum system. Paul you are right with the downdraft inlet idea of the 96+ dx civics, I have been thinking about that angle for awhile as well. I think most likely I will use the downdraft idea, with a collector that will snake out to 4 individual runners that feed each throttle body. There will be no plenum. The collector has to be designed so that it doesnt create turbulence upon the initial inlet so the air doesnt fight itself. You could think of the collector/runner idea of a reversed equal length exhaust manifold with a engineered collector.

I need to speak with my fluid dynamics professor for awhile about all the considerations I must take into account when designing this collector/runner. I will probably spend 100 hours of calculations, and developing a program on Mathcad that can model the airflow using different sizes/designs of the runner/collector idea.

I can say that one aspect of the itb with boost is that the engine will give stellar throttle response, and let the turbo spool up faster. The power gains are all going to come by engineering the plenum system.

If anyone else has ideas, please feel free to share. I dont consider anything I say to be the end all/know all of making this.

paulzy

iTrader: (1)

Now that I think of it, I think Gary Gardella's running ITB's on teh new setup isn't he? At least that's what I heard. Jeff, you should check it out, it might help you get an Idea for a PLenum.

THe collector Idea is nice, but then with that Idea you're gonna start restricting airflow to each TB because the air to teh TB will be coming from separate smaller pipes

93LSivic

I didnt really read the whole thread, but this is what I have to say.

ITB's are usually kept for the all motor guys for a few reasons. Quicker throttle response, more even air flow across each cylinder, no messing with load based tuning--usually tuned with throttle based, or TPS aided.
They arent a good idea for FI cause tuning is moslty done for the most part off of load based, ie. map sensor. Even air flow isnt a big characteristic in FI cause the plenum is pressurized evenly under boost.
I dont think it would work out so well, but I have thought about this personally in the past and I havent really came up with a good reason to try it.

Pengo

very interesting and nice to see such a technical post, and on our beloved d-series nonetheless. here are a few points i a was thinking about:

firstly is getting the same airflow and pressure to each itb from the charge pipe. i would imagine this would take quite some time to figure out and design, because if you can't get the air distributed evenly, then that kinda ruins the whole purpose right? but if u can figure that out like ur reverse equal length idea, then it may be doable.

secondly would be concerning the vacuum log. again, assuming u can deliver equal air across each itb precisely, all should be well. but say there are some differences between the air and pressure in each itb at some point. now all of the vacuum lines are running to the same vacuum log. how will this affect the accuracy of what the sensors are reading? and if this problem arises, how will this compromise the accuracy of your boost gauge? currently i can think of two possible solutions that would not work if the system isn't perfect. either tap vacuum from the log or one of the itbs itself. the third solution would involve monitoring pressure in each individual itb, which in itself would be safer, but would also drive up costs and sacrifice in cabin space to accomodate 3 extra gauges (all of which you could hopefully see easily).

i hope some of my points have made some sort of sense. still i understand there is still much research and work to be done, so kudos on your efforts and ideas. keep us updated on any new discoveries

PS: i must say i got a little bit excited when i saw how close the itb setup matches the intake ports

AB16A2T

Very nice, we need more posts like this.

boosted hybrid

If the plenum or runner system is designed well, then the vacuum/boost readings coming from each of the throttle bodies will be the same. The vacuum log is just a collection of the total vacuum or boost that is in the system. Since its a total, the sensors are just seeing the total vacuum/boost that the plenum would normaly see. Essentially the vacuum log takes the place of the plenum in the sense that it is the total vacuum.

The reverse equal length collection idea I think is the best that I can come up with. Each runner would not be the restriction as I am thinking about how the system would work. Each cylinder with the reverse equal length collection would be getting the maximum amount of air dispersed evenly across each cylinder. The airflow would follow the path that its provided, instead of "finding" its own path as with a normal intake manifold system. There would be no 90 bends for the air to flow into the runners, so turbulence will be kept to an all time minimum. Its just all theory at this point till I can sit down with my fluid dynamics professor and come up with some physical models that I can make using my knowledge of fluid dynamics. He is a associate professor, and works heavily in designing flow patterns for all kinds of industry including automobile. If anyone can give me a theoritical answer and point me in the right direction, its going to be him.

Also, there were some comments made that you could just turn up the boost a few more psi to compensate for overall flow. While this is true, what you are essentially saying is to ignore the overall efficiency by cramming more air into the air to compensate. While this would work, I am trying to figure out the more efficient way to feed air into the engine. If this would raise the efficiency of the engine 4-5% that would be pretty dramatic results. As far as money is concerned, its not going to cost that much to construct and build everything. I have the materials, I do all the welding/fabricating and all the theortical stuff is mainly for school anyways so I much rather be spending on car stuff. Even if this doesnt work, it gives everyone a much better idea that the conventional single throttle body system works better.

Sonny

Here' a pic of an Endyn modified Skunk2 manifold. Notice how each port is shaped differently in an effort to get equal air distribution to each runner.



That ITB setup looks bad ***. I understand what you're saying by trying to make an existing setup more efficient. Instead of upping the boost, why not just make more power by keeping the boost the same and more efficiently utilize the incoming charge.

Do you have any drawings of a reverse merge-collector design intake manifold?

Sonny

Full-Race Javier

didnt nissan switch over to ITB's from 1 TB for better throttle response, midrange, efficiency, and over all power?

here's an example of the ITB setup on an RB26DETT


or u can check out the Jun "surge tank" here
http://www.junauto.co.jp/produ...ml?en

i think i know what u are talking about with the reverse collector idea on the intake mani. we have one. we had one made for the SAE car here at school a few years ago. i'll find it and post some pics.

if u model it, try simulating it on a CFD program. this way u can change the runner lengths, volumes, placements etc and optimize all of them.

good topic

v8redneck

look man u want a real horse power car get a v8 ***

stizzit

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by v8redneck &raquo;</TD></TR><TR><TD CLASS="quote">look man u want a real horse power car get a v8 ***</TD></TR></TABLE>

oh now there's an idea