Hi everyone. Soon Ill be building an AEB intake manifold. Ill be running a Borg Warner EFR 6758 Twin scroll.. equal length tubular manifold. Im going for quick spool over max hp since this will be a road race car. I know ITBs can drasticly improve throttle response so im seriously considering building a 1 off set for my manifold. It will be a lot of work designing them and actually making them so Id like to make sure its worth doing. The plenum itself will be a center entrance dual plenum design. Intercooler will be mounted horizontal directly in front of the engine with the shortest air path possible. Radiator will be in the trunk. So has anyone seen this done? Think Its a good idea? worth the effort?
Nissan pulsars are turboed with ITB from the factory. Rear radiators work. Scandinavian rallyx cars uses this arrangement. Horizontal IC should allow proper air in/out control, as well as a shorter intake length Jon
A lot of top end turbo motors have itbs, but for a road/race car i'd question if they are really worth the bother.....unless you already have them. I was told they are a swine to balance up on a turbo car.
I looked at modifying my ITB`s to see if I could use them with F/I but for the minimal gains, I couldn`t see the point. IF I was in a class where boost was limited and efficiency mattered, fair enough, but quite honestly, I doubt I`d be able to tell anyway. A good tubular exhaust manifold will obviously help, but I`m not convinced it`s worth the time and effort to go for ITB`s too.
Most of the top end cars, such as the Skyline R32-R34 and the N14 Pulser, have the ITBs junked when tweaking for more power. But it may not be a track application though. For a 20v motor, I would more be concerned about the boost run, type of turbo and calibration method for turning on the turbo, than the hassle of adding ITBs. The new borg Warner EFR turbo is actually very good, based on a couple vehicles recently tuned.
thanks for all the input guys. right now its looking like a lot of time and work for potentally very little benifit and a possible big tuning headache. My plenum isnt going to ahve a ton of volume so a standard throttle body will most likely have fine response. I would be 100% building the throttle bodys and butterflys from scratch, aside from the shaft bearings and seals, so it would be a ton of work. It would be a single shaft style with no way to tune and adjust each butterfly individually. I think i can always cut a section out of the runners and install them later if I do decide to make them. I have no idea about tuning so I should probably not make it any harder for myself. I just made the turbo exhaust manifold flanges last night, next up will be the velocity stacks to make up with the AEB runners.
The motorcycle trick of adding a 2mm pipe tapping downstream of the butterfly always appeals to me. I have a set of 4 davida (google it) vacuum gauges that are lovely to use when balancing ITB's. Used them on the pulsar too. Jon
That would be the optimal way to go for sure. I was hoping I could get away with one central shaft that all the throttle plates would be connected to instead of individual shafts and linkage. In my mind one shaft with all the flats cut in one operation would put the throttle blades at exactly the same angle. The blades and ports, (housings?), will all have super tight tolerances held with cnc machines. Theoretically all the vaccumes SHOULD be the same but that's never the actual case in the real world. At the moment I'm leaning towards making a low volume dual plenum in hopes to keep it responsive with the quick spooling turbo.
The other trick is to measure vacuum to find leakiest one and then drill some 1mm (or whatever) holes in the other butterflies until you balance them up. crude, but........ Jon
I've had to do that to single throttle body's due to manufacturers specs to get the idle correct when the idle air control was deleted.
started on the actual manifold today. Tool a piece of square tube and milled one side flat, then tapped it with the manifold pattern. and this is the stock inlet for the AEB, much to be improved upon
Shaving the casting seams off of the stock runners And before anyone aske no its not done. Alot more machining of the velocity stacks to come.
It is thick for now. It has to be so I can get the proper radii milled into it for the bell mouths. 75% of that plate will be milled away.
