nkx Posted November 27, 2004 Share Posted November 27, 2004 Why cant you build boost when youre not in gear? Quote Link to comment Share on other sites More sharing options...
Tachometer Posted November 27, 2004 Share Posted November 27, 2004 Sure you can... When I installed my turbo gauge...right after, when I was very first testing I sat in the car, put it in neutral, and leaned onto the gas. Granted boost didn't build until much higher revs but it was there. I'm not EXACTLY sure...but this is a guess. Ever tried walking a dog? Let go of the leash and off it goes running. Hold the leash and he'll pull against it...building power. I'm guessing the engine needs that sort of "resistance" to really build exhaust flow. Like I said...guessing here. Quote Link to comment Share on other sites More sharing options...
archemitis Posted November 27, 2004 Share Posted November 27, 2004 the motor needs to be under load to buld boost. that and just reving it doesnt give it the time to creat boost. Quote Link to comment Share on other sites More sharing options...
WJM Posted November 27, 2004 Share Posted November 27, 2004 I does create boost...but not much. Not enough to get positive in the manifold before you have to let off or overrev. It will create enough boost under a hard rev to make BOV sounds when you have a BOV installed. Quote Link to comment Share on other sites More sharing options...
Subi81 Posted November 27, 2004 Share Posted November 27, 2004 I can get it to boost it I mash it hard in nutral, but only like a half a lbs or something at @ 3 grand. Quote Link to comment Share on other sites More sharing options...
nkx Posted November 27, 2004 Author Share Posted November 27, 2004 even if youre holding 4k rpm in neutral, where there would be enough exhaust gases to spin the turbo and build boost, you still dont make any. how does the presence of load contribute to building boost? Quote Link to comment Share on other sites More sharing options...
archemitis Posted November 27, 2004 Share Posted November 27, 2004 you gotta floor it, and hit 0 lbs of vac before you can start boosting it, holding it at 4 grand, or any lvl rpm wont do it, cuz your not floorin it. 0lbs of manifold pressure and vac get a boost/vac guage, it helps to understand Quote Link to comment Share on other sites More sharing options...
88rxsedan Posted November 28, 2004 Share Posted November 28, 2004 **** i can floor it from idle and by the time it hits 6k its made 7psi VROOOOOOOOOOOOOOO PSSSHHHHHHHHHHHHH Quote Link to comment Share on other sites More sharing options...
nkx Posted November 28, 2004 Author Share Posted November 28, 2004 ah, so load slows the engine down enough to give it time to actually make positive boost? Quote Link to comment Share on other sites More sharing options...
subynut Posted November 28, 2004 Share Posted November 28, 2004 Yup. Quote Link to comment Share on other sites More sharing options...
Tachometer Posted November 28, 2004 Share Posted November 28, 2004 ah, so load slows the engine down enough to give it time to actually make positive boost? ah HA! Beauty. Quote Link to comment Share on other sites More sharing options...
NorthWet Posted November 28, 2004 Share Posted November 28, 2004 The turbo responds to gas flow through it. At idle, the engine doesn't produce enough gas flow to spin our turbo enough to produce significant flow. Without a load, opening the throttle has the same effect as increasing the idle speed: The engine speeds up until the internal drag balances against the power produced by the increased intake flow, a point that still does not significantly increase exhaust gas production, and also produces relatively high-vacuum in the intake once equilibrium has been reached. If the throttle is opened fully, the engine speeds up as much as it can until internal drag matches the power produced, either due to limited intake flow or valve float. It doesn't take significant power to maintain no-load valve float, and that probably won't produce enough exhaust gas flow to spin the turbo to positive boost. It DOES take power to accelerate the engine, which acts as a transient load that could get the turbo spinning. But once steady state rpm is reached the load drops off and so would the power and the resultant exhaust flow. Quote Link to comment Share on other sites More sharing options...
jazzician Posted November 28, 2004 Share Posted November 28, 2004 Well, if you can get boost in neutral, that'd be cool as I'm trying to deal with a hesitation during boost. I was hoping to get fuel pressure readings but didn't think I could get the boost to kick in neutral so I could get readings. simon Quote Link to comment Share on other sites More sharing options...
operose Posted November 28, 2004 Share Posted November 28, 2004 Well, if you can get boost in neutral, that'd be cool as I'm trying to deal with a hesitation during boost. I was hoping to get fuel pressure readings but didn't think I could get the boost to kick in neutral so I could get readings. simon if what they're saying above is true, then I don't think you'll get accurate readings building a 'lil bit of boost in neutral... I don't own a turbo, but it would make sense to me that fuel pressure under tiny boost in neutral wouldn't necessarily be the same as fuel pressure under higher boost under load.. slap me if I'm wrong Quote Link to comment Share on other sites More sharing options...
oddcomp Posted November 29, 2004 Share Posted November 29, 2004 get a simple medical syringe a large one and tee in a vacumgauge/mechanical fuel pump gauge or a vac/boost gauge with it and hook i to the regulator and push/pull on the plunger to simulate vacum and boost conditions btw go to a vet place or feed store and get teh large ones used for giving mediacation oraly to cats doges horses ect fairly cheap Quote Link to comment Share on other sites More sharing options...
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