art leong Posted February 22, 2013 Report Share Posted February 22, 2013 I'm running Individual throttle bodies. I have a vaccum box about 1 inch sguare x 6 inches all four intake runners feed it. My problem is at low rpms with vaccum the signal bounces like mad. At wide open throttle it is fine but driving around the pits it is eratic and hard to tune. I'm thinking about using a restrictor in the line near the ECU this might calm the signal down, or maybe a pair of restrictors leading into and out of a mini manifold. Does anyone have any thoughts on this? Thanks PS this is a naturally aspirated motor, no boost. Quote Link to comment Share on other sites More sharing options...
BMW2002 Posted February 23, 2013 Report Share Posted February 23, 2013 Maybe you can use dual map`s and run on tps below a certain map set-point? I had to use tps instead of map at low loads and idle on my bmw m10 turbo with 304* cam due to high "overlap"and lack of vacuum. Quote Link to comment Share on other sites More sharing options...
Sutkale Posted February 23, 2013 Report Share Posted February 23, 2013 As far as I´m concerned, N/A engines are always tuned TPS as primary load source. With Vipec TPS as primary load source for boosted engines works like charm also. Quote Link to comment Share on other sites More sharing options...
art leong Posted February 24, 2013 Author Report Share Posted February 24, 2013 I've got a race in a 2 weeks, with a test session day first. I'll try it then. A couple of people have told me to do that. Thanks Quote Link to comment Share on other sites More sharing options...
QueenRacing Posted February 25, 2013 Report Share Posted February 25, 2013 You can also build a small canister, 3 in long and a 2 in pipe with caps welded on the ends. Then put the vac line feeding into this and one coming out and it will mellow out the large pusle. It works well with my large bore 2 cyls and ind throttle bodys.. Quote Link to comment Share on other sites More sharing options...
bsh Posted February 25, 2013 Report Share Posted February 25, 2013 If you have cams with large overlap, you will get a very weak manifold vacum and it is useless to try to tune with map as load. Use tps as load. Quote Link to comment Share on other sites More sharing options...
art leong Posted February 26, 2013 Author Report Share Posted February 26, 2013 I have 3 races in 3 weeks coming up. As soon as I get them done I'm going to change to TPS instead of Map. Don't want to change it before the races. It's running fast enough now to get me in trouble. I play when there are no NHRA eyes around. Thanks all, Quote Link to comment Share on other sites More sharing options...
art leong Posted February 26, 2013 Author Report Share Posted February 26, 2013 You can also build a small canister, 3 in long and a 2 in pipe with caps welded on the ends. Then put the vac line feeding into this and one coming out and it will mellow out the large pusle. It works well with my large bore 2 cyls and ind throttle bodys.. That is what I'm going to do right now, with a vacuum restrictor on the map side. It should make the car run cleaner in the pits. Cleaning fuel fouled plugs before I stage is part of the problem Quote Link to comment Share on other sites More sharing options...
art leong Posted March 6, 2013 Author Report Share Posted March 6, 2013 You can also build a small canister, 3 in long and a 2 in pipe with caps welded on the ends. Then put the vac line feeding into this and one coming out and it will mellow out the large pusle. It works well with my large bore 2 cyls and ind throttle bodys.. Did this used PVC pipe and put a vacuum restrictor on the MAP side. I helped a lot. Now it varies only 5 KPA at most. Quote Link to comment Share on other sites More sharing options...
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