Guest bastaad525 Posted August 31, 2005 Share Posted August 31, 2005 hey all... this is a real 'chicken or the egg' type question that has kept me going in circles for a couple days... basically, I'm trying to minimize boost spiking with this grainger valve boost controller I'm running. And I'm wondering, exactly what effect the diameter of the hose going to and from the controller would have on the spiking. I'm thinking it could be two different ways: 1. a smaller diameter hose would INCREASE spiking, due to the increase in effort it would take the boost air to 'fight' it's way through the hose. Think of blowing through a straw. It's much harder to blow through a smaller straw than a larger one, so wouldn't it be harder for the boosted air to get thru the smaller hose? End result, it takes that fraction of a second longer to reach the controller and then on to the wastegate = delay in opening wastegate = more spike 2. a larger diameter hose could ALSO increase spiking. Because there is that much more volume to fill before the full pressure reaches the controller and the waste gate. Think of an intercooler... when you add an intercooler, boost lag is increased because it takes that much longer to fill up the full volume of the I/C before the boost reaches the manifold. Same would happen if you switched to a larger I/C... lag would increase. So a larger hose to the controller and wastegate = more 'lag' of boost signal reaching them = more spike before wastegate opens. what do you guys think? should I run larger or smaller hose?? Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted August 31, 2005 Share Posted August 31, 2005 When is it spiking? I know on some of my home made MBCs, drilling a tiny vent hole helped a lot. I did this to the first one I made because it would spike if I was in high revs then suddenly punched it, but didn't if I started down low in the rpm range. I don't think the hose diameter really matters for the very short runs you should be doing for the MBC. Unless it's WAY too small. Mario Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 31, 2005 Share Posted August 31, 2005 it ALWAYS spikes whenever I floor the gas and boost comes on, it spikes to 15psi before settling on 13. Doesn't seem to matter what RPM I'm at, what gear I'm in, or anything else. I did already drill the .020 vent hole in the outlet nozzle of the MBC as per the walkthru on how to put it together. I've shortened the hose as much as I can between everything, didn't seem to help. Quote Link to comment Share on other sites More sharing options...
Thumper Posted August 31, 2005 Share Posted August 31, 2005 If you are having problems with spiking. Something you can do is put a softer spring in there. Therefore the ball will move more of distance between 13psi and 15psi since the spring will compress more. The longest softest spring you can fit will make it less likely to spike but make spool up a tad bit slower. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 6, 2005 Share Posted September 6, 2005 ...everything above and maybe a stiffer hose. I am using heavy wall black rubber vacuum hose about 1/4" ID. Like I said before I get imperceptible boost spike but I have a bigger turbo that spins up slower. However, I remember having no spike problems with the stock turbo either. It's all about the reaction time of the wastegate actuator to the boost pressure at the source. Maybe exhaust back pressure could make the wastegate open more slowly too? I am not an expert on this one though. Quote Link to comment Share on other sites More sharing options...
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