ITB Setup top end performance.
12-19-07, 12:29 AM
#27
Rotary Enthusiast
iTrader: (1)
Join Date: Oct 2005
Location: Raleigh, NC
Posts: 1,017
Likes: 0
Received 0 Likes
on
0 Posts
I've got more or less the same setup. I have the fuji racing ITB's that bolt on to a sidedraft manifold. I am using the Megasquirt 2 V3.0 board and in the final stages of getting it back up and running. Playing around with software stuff now. All the hardware is done. You can follow up from either here:
https://www.rx7club.com/1st-generation-specific-1979-1985-18/fuji-racing-itbs-finally-d-683967/
or here on the full build
https://www.rx7club.com/1st-generation-specific-1979-1985-18/progress-my-car-pics-d-695200/
BTW my engine setup is a 12a with a fairly large streetport. I'll be mostly comparing the dyno run to my old holley setup which netted 147 rwhp with stock ignition and running fairly rich. Dyno graph can be seen here:
https://www.rx7club.com/showthread.p...highlight=dyno
https://www.rx7club.com/1st-generation-specific-1979-1985-18/fuji-racing-itbs-finally-d-683967/
or here on the full build
https://www.rx7club.com/1st-generation-specific-1979-1985-18/progress-my-car-pics-d-695200/
BTW my engine setup is a 12a with a fairly large streetport. I'll be mostly comparing the dyno run to my old holley setup which netted 147 rwhp with stock ignition and running fairly rich. Dyno graph can be seen here:
https://www.rx7club.com/showthread.p...highlight=dyno
SOOOOO stoked that someone is using the Fuji ITBs. I am going to follow your set up closely and would love to hear how it all works out. I have been vacilating between going with the ITBs, lighten flywheel and really short geared rear end, going V8, or ditching the RX7 all together to go to a supercharged MR2S. this could help sway me. What I am particularly interested in is the throttle response, power increase and, in particular, the sound.
Keep us updated.
BC
03-11-08, 11:16 AM
#34
Rotary Freak
Been There, Done It, Have the T-Shirt
YAAwwwn........
Sorry drifted off there for a second. We did this last year and it is a monster effort. We built the manifold from scratch and tuned the car. It tooka ton of work to get running well. I am not trying to put anybody off from doing it, I just want you guys to know it is a ton of work and a ton of work to tune.
Big issues that need to be overcome:
1) Air Fuel ratios are like a light switch when the throttles are opened
2) Vacuum goes to zero as soon as the throttles are opened
3) Throttle tip in is a b!t$h to tune
4) The car needs more fuel than you can imagine
5) Developing an air filter set up is a pain
6) Custom fuel rails need to be made
7) Position of injectors in system has a major effect!!!!!!!
8) Any reasonable length runner moves the torque peak way way up
9) For street the runners need to wrap over the top of the motor and lots of stuff needs to be moved
Other than this stuff it is easy, LOL. On the plus side the car has throttle response like an F1 car. It makes tons of power/ torque. IT IS REALLY REALLY COOL!!!!!
Eric Nummelin
Sorry drifted off there for a second. We did this last year and it is a monster effort. We built the manifold from scratch and tuned the car. It tooka ton of work to get running well. I am not trying to put anybody off from doing it, I just want you guys to know it is a ton of work and a ton of work to tune.
Big issues that need to be overcome:
1) Air Fuel ratios are like a light switch when the throttles are opened
2) Vacuum goes to zero as soon as the throttles are opened
3) Throttle tip in is a b!t$h to tune
4) The car needs more fuel than you can imagine
5) Developing an air filter set up is a pain
6) Custom fuel rails need to be made
7) Position of injectors in system has a major effect!!!!!!!
8) Any reasonable length runner moves the torque peak way way up
9) For street the runners need to wrap over the top of the motor and lots of stuff needs to be moved
Other than this stuff it is easy, LOL. On the plus side the car has throttle response like an F1 car. It makes tons of power/ torque. IT IS REALLY REALLY COOL!!!!!
Eric Nummelin
03-11-08, 11:50 AM
#36
Did you stage the secondaries to come on later? I was thinking of doing this crazy setup once but was concerned for the following reasons you listed below
. I figured if you staged the TB's you could better maintain driveability.
. I figured if you staged the TB's you could better maintain driveability. YAAwwwn........
Sorry drifted off there for a second. We did this last year and it is a monster effort. We built the manifold from scratch and tuned the car. It tooka ton of work to get running well. I am not trying to put anybody off from doing it, I just want you guys to know it is a ton of work and a ton of work to tune.
Big issues that need to be overcome:
1) Air Fuel ratios are like a light switch when the throttles are opened
2) Vacuum goes to zero as soon as the throttles are opened
3) Throttle tip in is a b!t$h to tune
4) The car needs more fuel than you can imagine
5) Developing an air filter set up is a pain
6) Custom fuel rails need to be made
7) Position of injectors in system has a major effect!!!!!!!
8) Any reasonable length runner moves the torque peak way way up
9) For street the runners need to wrap over the top of the motor and lots of stuff needs to be moved
Other than this stuff it is easy, LOL. On the plus side the car has throttle response like an F1 car. It makes tons of power/ torque. IT IS REALLY REALLY COOL!!!!!
Eric Nummelin
Sorry drifted off there for a second. We did this last year and it is a monster effort. We built the manifold from scratch and tuned the car. It tooka ton of work to get running well. I am not trying to put anybody off from doing it, I just want you guys to know it is a ton of work and a ton of work to tune.
Big issues that need to be overcome:
1) Air Fuel ratios are like a light switch when the throttles are opened
2) Vacuum goes to zero as soon as the throttles are opened
3) Throttle tip in is a b!t$h to tune
4) The car needs more fuel than you can imagine
5) Developing an air filter set up is a pain
6) Custom fuel rails need to be made
7) Position of injectors in system has a major effect!!!!!!!
8) Any reasonable length runner moves the torque peak way way up
9) For street the runners need to wrap over the top of the motor and lots of stuff needs to be moved
Other than this stuff it is easy, LOL. On the plus side the car has throttle response like an F1 car. It makes tons of power/ torque. IT IS REALLY REALLY COOL!!!!!
Eric Nummelin
03-11-08, 12:09 PM
#37
Rotary Freak
Nope, all 4 at once. When I converted to Alpha N it all became good and tip in, response was fine. You also have to remember that this is a race car and we don't really worry about part throttle too much. If it pulls from low rpm cleanly and makes big power, we are happy. The Holley set up was far worse for response and driveability.
03-11-08, 12:43 PM
#38
Thanks for the info, I just wonder how well this would work on a boosted FD pushing 18 psi through the setup..
Nope, all 4 at once. When I converted to Alpha N it all became good and tip in, response was fine. You also have to remember that this is a race car and we don't really worry about part throttle too much. If it pulls from low rpm cleanly and makes big power, we are happy. The Holley set up was far worse for response and driveability.
03-11-08, 03:48 PM
#39
23racer, I remember seeing your picture when you were building them at Joe's shop. Did you ever dyno the car yet? If yes would you be able to provide figures or even better a graph? I might be interested in getting this done to my 12a later on down the road and would be nice to know what gain figures are there.
Sam
Sam
03-11-08, 04:07 PM
#40
Rotary Freak
Joe had them welded up, but they were designed and fabbed at my shop.
Anyways, I haven't had a chance to dyno thye setup yet as we just worked out all of the mapping issues in October, then found out that the TII injectors and stock pump wouldn't flow enough gas to allow the car to run above 6500 rpm. It started to snow after that so I haven't put the bigger pump in yet.
With my new 310 hp ex WC Cougar I am playing with now, the RX is sorta retired for a while and it may be a few months before we get it dynoed.
Eric
Anyways, I haven't had a chance to dyno thye setup yet as we just worked out all of the mapping issues in October, then found out that the TII injectors and stock pump wouldn't flow enough gas to allow the car to run above 6500 rpm. It started to snow after that so I haven't put the bigger pump in yet.
With my new 310 hp ex WC Cougar I am playing with now, the RX is sorta retired for a while and it may be a few months before we get it dynoed.
Eric
03-11-08, 10:03 PM
#42
Lives on the Forum
It doesn't seem like he's using an air box, not that I blame him, there can't be much room for one there. Without an air box and intake tube you can't really use a MAF.
03-12-08, 07:42 AM
#43
Rotary Freak
We were using a setup developed off the Aussie IPRA cars ITB setups. They don't use MAF's as the drivability improvement is at a potential cost of HP and complexity. They have been running these setups for years and they make gonzo hp above 5000 rpm to 11,000 + rpm. As we are rarely below 5,000 rpm and only plan on turning the motor to 9,500 rpm we didn't feel the added complexity of the MAF was necessary. We wanted to go with a system that was well proven in performance advantage and that had some guidelines for tuning of intakes and exhaust systems. We have a different type of exhaust, as well, that helps take advantage of the ITB's.
As to a cold air box, we still need to build one but have spent most of our time getting ready for the 2008 season with the Cougar. It is well worth it and the system was designed to allow one. It is very tight, but there is over 4 inches between the ends of the trumpets and the shock tower to fit one in. If we run the car some more, that is the next thing to fab. We have already built the base plate.
By the way Black91N/A, are you guys going to do the new 12 hours at Portland in the fall?
Eric
p.s. Dave, my race engineer spent about 2 weekends straightening up and tidying up under the hood after these shots were taken. He hates it when I post photos from that weekend. These shots were right after we got the whole thing running for the first time. We also added filters and some heat shielding.
As to a cold air box, we still need to build one but have spent most of our time getting ready for the 2008 season with the Cougar. It is well worth it and the system was designed to allow one. It is very tight, but there is over 4 inches between the ends of the trumpets and the shock tower to fit one in. If we run the car some more, that is the next thing to fab. We have already built the base plate.
By the way Black91N/A, are you guys going to do the new 12 hours at Portland in the fall?
Eric
p.s. Dave, my race engineer spent about 2 weekends straightening up and tidying up under the hood after these shots were taken. He hates it when I post photos from that weekend. These shots were right after we got the whole thing running for the first time. We also added filters and some heat shielding.
03-12-08, 09:34 AM
#44
Lives on the Forum
That's good to hear, plenums can be quite helpful, especially just to make it easier to get filtered air in there. Especially where it's at now you'd be getting hot exhaust heated air.
I'll likely be at the 12 hours of Portland, not driving, but as crew/race engineer. The guy I crew for has sold his old GT3 class BMW 2002 and is in the process of buying something much quicker (details will come once it's safely in our hands). He wants to get into endurance racing in a big way and plans to do a 25 hour race at Thunderhill (the car's done it before and done made it onto the podium) as well as the other ICSCC enduros.
I'll likely be at the 12 hours of Portland, not driving, but as crew/race engineer. The guy I crew for has sold his old GT3 class BMW 2002 and is in the process of buying something much quicker (details will come once it's safely in our hands). He wants to get into endurance racing in a big way and plans to do a 25 hour race at Thunderhill (the car's done it before and done made it onto the podium) as well as the other ICSCC enduros.
03-12-08, 10:19 AM
#45
Rotary Freak
It looks like I may have an opportunity to be running the Brown Bros. Cobra R car again this year. It should have a new motor after sawing its last motor in half at the 4 hour in Seattle after breaking a valve spring while leading by 3 laps over second place with 30 minutes left...........$#%@. The extension to 12 hours has added the need for another driver again. I am going to keep my fingers crossed.
As well the changes to Mission have made that a more desireable track. I have a couple of friends out there who want me to ship the RX to Vancouver so that I can run it on the West Coast. I won't be able to run it at Mission as the intake noise exceeds 92 db's, LOL.
Eric Nummelin
p.s. I am using filter socks over each trumpet now.
As well the changes to Mission have made that a more desireable track. I have a couple of friends out there who want me to ship the RX to Vancouver so that I can run it on the West Coast. I won't be able to run it at Mission as the intake noise exceeds 92 db's, LOL.
Eric Nummelin
p.s. I am using filter socks over each trumpet now.
03-12-08, 10:27 AM
#46
Hey Eric,
Anyway of providing a picture of the headers? I'm not going to ask about anyspecific details as I know giving info like this means you just giving all your secrets. Also any shots of the "cleaned up" engine bay? It would be nice to maybe see your car sometime in the summer and to meet you in person.
Sam
Anyway of providing a picture of the headers? I'm not going to ask about anyspecific details as I know giving info like this means you just giving all your secrets. Also any shots of the "cleaned up" engine bay? It would be nice to maybe see your car sometime in the summer and to meet you in person.
Sam
03-12-08, 11:16 AM
#47
Lives on the Forum
Hopefully that'll work out for you. I'll be posting details if we are going to be going there, as the car should be of some interest to the people on this board.
03-12-08, 11:50 AM
#48
Rotary Freak
Sam, the headers are just basic Racing Beat headers. The trick is in the pipe diameter and length, the type of collector and the after collector exhaust diameter and length. I had to do a ton of research to figure it out and it really seems to work as the car now has enough torque to actually pull the skin off a bowl of rice pudding, LOL.
I just have the shot from the Toronto Indy Weekend. Since that time we added some heat shields between the intake and exhaust and sock airfilters.
When I get back from LA I will go over and try to take an updated shot.
Eric
I just have the shot from the Toronto Indy Weekend. Since that time we added some heat shields between the intake and exhaust and sock airfilters.
When I get back from LA I will go over and try to take an updated shot.
Eric
03-12-08, 11:43 PM
#49
Thanks Eric, how much torque do you think was gained overall from manufacturing the proper exhaust? I'm thinking about doing the same things right now. Basically with a decreasing and increasing slope at the end of the collector. not sure if this is what you used or not. But from researching with the Formula SAE car that we worked on and doing the intake system (we have a 20mm intake restriction) by moving the location of the smaller inner dimension within the tube and running simulations, we found that at various areas the pressure can be dropped. Now because there's a higher pressure difference, what that really translates to if more flow (CFM) that can be passed through the passage. Something like this in the exhaust system would enable the exhaust gases to "pulled" our sort of speak instead of just pushed out by the engine making the engine do less work and more torque provided to the wheel, which would also increase your HP figures. The problem as you might of found out is that it takes lots of trial and error to get all the figures right as there is no way of just figuring out the exact dimensions needed.