Anyone got pics showing ITBs/bike carbs mounted to a standard PB style head. Also would people use an intake tract similar to what is found on BMW M3s to prevent them sucking hot air from the exhaust.
I'll dig some pics out... There's generally no probs with heat as long as you fit a heat shield between the inlet and exhaust manifolds. Air temp readings out on the road of low 20's on a warm day show this to be effective.
I never had any problems. I had the exhaust heat wrapped and a heatshield between the carbs and exhaust manifold, using an aquarium temp guage thingy to keep an eye on temps. As long as you dont sit in traffic too long on a scorching day you won't have any probs. Like Mr H says, temps rarely get above 20deg once moving.
On the subject underbonnet temps for reference my 16v X-flow ITB'ed cars under bonnet temps were measured above the exhuast manifold and would be around 20 deg on the move, in traffic this would rise up to max 50deg after some time, the temp would clear very quickly once moving again, the inlet air temp for the ITB's would be very close to the measure temp above the exhaust even tho' there is a large distance between the two.
great can someone please confirm if the black slide thing in the carb behind the butterfly in the pic below is part of the choke mech. If so how does it work. I was playing around with the carbs and can feel air when the black part is slid out of the way by hand. I have pushed/pulled what ever I could on the carbs but cant get the black slides to move. The carbs are Mikuni
No, that is not part of the choke mechanism. Those carbs are CV carbs that work on the the variable venturi / constant vacuum principle, as opposed to fixed venturi / variable vacuum. Basically those black slides are lifted by a diaphragm depending on engine air demand, they in turn lift the needles that alter the fuel ratio admitted to the engine. The choke mechanism merely opens a jet to allow more fuel to be admitted instead of choking the air supply to richen the mixture.
does that mean Ive bought the wrong type for this sort of setup running on MS? sounds complicated I didnt realise they'd be using vacuum.
For an EFI setup like MS you need ITBs, not carbs. Here are a couple of examples. These are a Cosworth design that was made for the VW 8v engines back in the day. They used a mechanical injection system so had no provision for a TPS. (ignore carb in back ground) And these are a set of GSXR ITBs. They are an EFI design and have a TPS as standard. Depending on use they can make it awkward to map due to the large difference in airflow for small increase in throttle position. They sometimes come with secondary butterflies and a controlling module to calm the airflow down a little.
found this link explaining more about the carbs http://www.bikerenews.com/Stories_Archives/Carburetors.html so theres no way of using these carbs with MS? Do ITBs still use the original fuel rail and injectors? I guess I wrongly assumed the Bike carbs and ITBs were similar.
The carbs are not really suitable for use in an MS setup. Depending on their size they should be easy to punt on to some Civic or Polo owner. Is there any specific reason for going to ITBs over a plenum design? There are few folk that have had decent results with the oem style plenums and it does make the setup a lot easier as there are a lot less bespoke bits required. Mr Hillclimber will no doubt post up TonyBs engine which is a cracker, but at the very high end of what is possible. So unless going to the limit then it may be easier to utilise an easier method. Mike_H and Drunkenalan both use MS on 8v counterflows.
no real reason really just thought it might be a bit of fun experimenting with something new also thought it would give it more go but guess that may not be the case. I was also pondering turbo options but thought ITBs might be a simpler project to get my head round first and then maybe move onto turbo like things
If you are going through the trouble of running itbs, I would not install on an 8v engine with stock compression. Based on your current baseline, you will have further torque benefits with the plenum system using the the SEM. ITBs will allow slightly higher rpm with less average torque and around the same peak power, if you were to use the std compression. From what you will see when the analysis of the 8v and 16v dyno day s posted, for the effort, you would have been better just sticking an ABF engine in there. Turbocharging takes things to a whole different level though - towards lightly fettled 1.8T w/K03/maybe K03s.
Right the ITB route is officially aborted looks like turbo may be the only way but I think I will wait and see what difference MS makes initially before biting off more than I can chew. Now going to check the abbreviations thread to find out what SEM means
You could use MS to map the ignition only, but you'd have to fit a TPS to the carbs, and it's probably not worth it. Fuel control would be as per any other carb... roughly right but a bit crude for a more modern car that needs to be reliable for road use, pass MOTs, etc. As you said, you should megasquirt the car first, to get yourself up that learning curve.
the carbs do have a TPS on there (untested) but if I am spending the money on SEM then I should be getting the most out of it and fiddly crude carb adjustments will prevent that. thanks for all the input guys atleast I now know the difference between bike carbs and ITBs
