dj55b

iTrader: (2)

This idea has been pondering in my head for sometime now and was woundering what the outcome of such a thing would be. This would be for an NA setup. The Idea that I have is putting on 4 ITB's, now you say thats nothing new, but the way I'm thinking is having is basically a hack up of a Side Draft and a Lake city style Manifold. The primary port would have the lake city style adapted to it, and the secondaries would have the sidedrafts hooked on them. As for fueling, not stages but all at the same time.

Has anything like this been done before? If so anyone know the torque curve outcome of it along with the HP curve? Or atleast what it would be like or if its just a totally stupid Idea.

Sam

orion84gsl

iTrader: (5)

I've also been pondering this, so engineers and knowitalls, tell us why it won't work

Jaime Enriquez

I've seen it done with 4 throats, 45mm motorcycle throttle bodies on an Rx8 and such. Guru in Oz has a 4 throttle intake, as does Judge Ito in his N/A Rx3...(search it up, its been done)

Usually done with 2 throats like and IDA Weber carb, which does very well.

23Racer

I worked on a system over the last 2 years and now have it running. I have to admit it has been a bit of a trial. It required a lot of work to determine the proper runner lengths (including what is a runner length, does it include the bells and ports in the motor) and I.D.'s of the runners.

I ended up with Hayabusa bodies, 50 mm inlets, 42 mm chokes, a custom built intake, combination of stock Mazda fuel rails and custom fabbed, cool throttle linkage issues, a programable ECU and the need to create a cold air box.

I will admit that we have struggled with the mapping to get the car running right. We tried to have it run on a standard type of MAP and have wasted 4 hours on a dyno and 3 sessions on-track. We have now converted to an Alpha-N style (TPS/RPM based only) and hope to have better results. The main issue with a standard type of map is that the vacuum signal goes all over the place and causes all kinds of unwanted enrichments and leanness. The best we got was great driveability using less than 1/3rd throttle and great full throttle, but terrible anywhere else. If you are really planning on using this system plan on Alpha-N from the start.

Regarding power, the only dyno run that was halfway normal we only ran up to 4000 rpm and we were developing 135 rwhp on a Dynopak. On a positive note at Mosport last race, on the back straight when the car cleaned up and pulled hard, the pig pulled hard enough to pass a bunch of cars and run with the class leaders for the one straight.

Some video's for your enjoyment.

http://video.google.com/videoplay?do...57026121160877

http://video.google.com/videoplay?do...69563795267888

Eric

RacerXtreme7

iTrader: (2)

It's been done numerous times in the past by various people, but seldom documented withen the forums, at least in any kind of detail. I know "TheHitMan" of Australia (a well known tuner) tuned a simular set up. It was a 13b full bridge, it started life DCOE carbed, then the owner fab'ed a custom intake running 4 ITB from a motorcycle very VERY simular to the one above. No matter how they tuned the Haltech, it LOST more then 15 hp on the top and torque SUCKED throught the powerband. ITB's are very sensitive to diameters and length, so even after you *think* you got it mathmatically sorted, you'll still need dyno time to get it right and a couple different manifold lengths, diameters, etc. Tunning can be tricky, 23Racer, I don't know how you had the MAP sensor hooked up, but if you run a vac source from each runner (all four) and then "T" all them together and run your MAP source from there you'll find that it will smoth things out and make tunning a BOAT LOAD easier and more consistant. It'll be much more refind then Alpha-N, but if its a race car, I suppose Alpha-N is fine. BTW, super nice work!!

Last little note, Theres quit a bit of extra power to be had by moving the secoundary injectors further out. So far out in fact you can inject straight down the bell mouth. I'd only recommend this for high load/RPM and run a primary injector behind the throttle blade for low load/RPM/idle, otherwise you'd get fuel all over the engine bay.

~Mike............

23Racer

Mike, I agree with everything you said. I had a little help in putting the manifold together. I talked it over with Rohan Ambrose at the last PRI Show in Orlando. He wanted to know what I was looking at for an RPM peak and power band and after I gave it to him he suggested a length and I.D. and it came very close to the calculations.

Regarding the vacuum, we had all the throats "T"ed together and still the vacuum had a ton of pulses, but the bigger issue was the effect of throttle tip-in on vacuum. Just a small amount of openning would result in a drop to atmosphere and the mapping to correct that didn't want to work at larger throttle openings. We just couldn't get the car MAPPed for the mid rpm and mid throttle opennings.

The car needed a sliding scale of accel pump shots based on vacuum and tps and rpm. I expect if we spent months tuning we could come close, but all the Aussie IPRA guys advised me to go to tps as load (or Alpha-N). The best advice I got was to run on MAP at lower rpm and tps at higher, sorta a mixed system. Should work fine.

I race the car, so I don't really care about mileage too much or emissions (at all, the car is a stinky beast). I would not look at this at all for the street. The airflow from a dual throat would be far more responsive on the street.

He%#, last year I ran a 650 Double Pumper Holley on a Racing Beat Intake. This set-up has to out perform that, LOL. I will check out Hitman's site. Thanks for the reminder

Eric

RacerXtreme7

iTrader: (2)

Not trying to change your mind, just keeping the conversation going, but maybe a surge tank'ed type of vac manifold/canister. Basically run all 4 vac lines from each intake runner to a vac canisters or surge tank. It shouldnt need to be too big (I'm thinking 1.5" diameter tube maybe 6" long. Then tap MAP from there? I had a Racing beat Dellorto' 48 DHLA system, and low load/tip in was a BIOTCH to smooth out. Maybe it was my ignition too, but evetually I went dark side and turbo so i never worked it out. I had planned on using a TMW twin throat 50mm side draft throttle body to replace that Dellorto', but I just ended up using a 3rd gen upper mated to a s5 lower turbo manifold for my now turbo block (the Dellorto' system was on a ported n/a 6 port).

BTW, I couldn't find the ITB system on HitMan's sight. This was like nearly a decade ago when he had it up there.

~Mike............

dj55b

iTrader: (2)

Thanks for the info guys ...

23racer - You're the guy that Joe from RPM did that manifold correct?

As for the rest, my plan is not to make all equal lenght runners, but to have 2 different type.

Also would you guys know if having a longer runner like a over the engine side draft setup, because of the longer lenth would give a slightly better signal? Either way I just purchase some ITB's from Fuji Racing and just running that for that to get started and learning a bit more about FI. I have heard of all the Map problem and hope that I don't get that kind of stuff.

I'm going to try to make my own Tubular manifold soon, with sidedraft weber intake plates on there.

23Racer

Just to be clear, what Joe did was take the pieces I made to a guy he knew that welded aluminum very well. I designed and fabbed the pieces. Joe had the manifold at his shop for a while before I picked it up. I don't know if wants to take responsibility for the piece.

Mike, your idea on using a surge tank for the vacuum signal is a good one and one my crew chief and I have said that we want to try. The only issue I see is that you add another variable to the system that could act as a signal modifier and cause a lag.

My problem with continuing to research the MAP side is that we need it to run okay by Labour Day Weekend and the Alpha N is a lot simpler.

DJ55b, in researching the runner lengths I found that to get a horsepower peak at 6,000 rpm, I needed a runner length of just over 12 inches and a runner i.d. of 44 - 45 mm.

RacerXtreme7

iTrader: (2)

Moreover on the subject, trying to run seperate lengths and diameters on the same rotor is going to be tricky and the results I'm sure you'll find to be disspleasing unless you staged throttle body openings (reffering to the orginal poster here). I'm getting the impression your going to run longer and smaller runners for the primary and larger diam and shorter for the seconday right? Bets of both worlds, good low end and top end? Well, this is why MAZDA built the intake systems the way they did. Your gonna find that if you open all 4 TB's at the same time and have anythign other then slight differances in the intake runners from one side of the rotor to the other that any intake velocity your trying to gain my making the primaries smaller/longer wont work too great because all that resistance will be made up for with mor flow from the larger/shorter slower velocity secondary side. You have to stage them and force the engine to suck from the primary at low load/rpm and then let it do what it wants at high RPM with all the throttles open. The ITB's if your running them all linked the same works best if the port timing and intake runners are simular. Its HARD to get them simular, hense the weirdo MAP signals.

You could stack two double throat TB's on top of one another and make a special progressive linkage, or even easier get a holy type manifold and run a Holly type TB and stage there opening.

~Mike............

R.P.M.

iTrader: (3)

dj55b, I didn't make 23racers intake setup, he made everything and I had a freind weld it together for him. It turned out really well and works great!
Hopefully Eric, you can get the bugs worked out and we can see some final dyno numbers from that motor.

dj55b

iTrader: (2)

Ah ic ... well i just remember seeing the thread and you posting the pictures up and I just connected the dots wrong.

DaveB

Grassroots Motorsports used a TRW ITB setup on their 1st gen build project car done in 1994. It was used on a Petit built 13b in the car. I have that engine in boxes in the basement just waiting to decide which tub it goes in.

dj55b

iTrader: (2)

Care to post up some pictures and specs of the system? Interested to see what is what.

DaveB

I will look through all my photos and see if I have any. Otherwise I could scan the article. All the parts are in boxes in the basement. By the way......the car is for sale right now in ITA trim with a 12a in it if anyone is interested. It could probably be had for a grand since the current owner isn't going to race it. He used it for 2 track days I believe.

dj55b

iTrader: (2)

You're selling the ITB's with that grand? or just the car shell basically?

DaveB

I don't own the car....just the blown 13b and fuel system. The car is complete with a legal ITA/IT7 engine at this point and is offered for sale. I am planning to put that Petit built engine in my 87 Sport for some fun. It dynoed at 200+ RWP in that car.

Bluem

can i use 3 47mm throttle bodies and have the primary ports share a throttle body

dj55b

iTrader: (2)

that could be doable, might be easier to tune, especially at idle, and might a bit better vacum signal.

Bluem

Will Running The Vacuum Lines To A Canister/reservoir Nand Have The Map Sensor Connected To It ?