Why am I loosing boost after VTEC?
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Senior Member
Joined: Mar 2004
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From: Seattle, WA, USA
Why am I loosing boost after VTEC?
I have a '99 Base Prelude with a Greddy turbo kit. I was messing with the wastegate actuator to get the boost right. I got it right where I want, but according to my boost gauge, it holds about a good 8 psi until VTEC, and then drops off to like 6 psi. I don't know why?! It stays right at 8 lbs through the whole RPM range, but then once I get to about 5500 - 6000 RPM, it drops off to 5 or 6.
There is a hole in my downpipe that I'm getting welded on Thurs, but that wouldn't effect the boost would it? Please let me know if you guys have any ideas, thanks!
There is a hole in my downpipe that I'm getting welded on Thurs, but that wouldn't effect the boost would it? Please let me know if you guys have any ideas, thanks!
Joined: Apr 2002
Posts: 3,523
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From: W.A
Re: Why am I loosing boost after VTEC? (redteg1)
Whats the pre-set psi for that kit?
Sounds like the turbo my be running out of steam with the higher boost setting.
I Know nothing about the greddy kit so this is just a guess.
I had the same problem n my b16 with a t3. swapped it out for a t3t4 and fixed the problem
Sounds like the turbo my be running out of steam with the higher boost setting.
I Know nothing about the greddy kit so this is just a guess.
I had the same problem n my b16 with a t3. swapped it out for a t3t4 and fixed the problem
Junior Member
Joined: Jan 2001
Posts: 251
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From: Montreal, Qc, Canada
Re: Why am I loosing boost after VTEC? (xPRELUDEx)
Look around the air filter piping, maybe there's a restrictor plate like they did for B series. My friend's teg was doing the same until we removed that plate 
I don't know why they put that there, emissions ??
I don't know why they put that there, emissions ??
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Honda-Tech Member
Joined: Apr 2002
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From: atlanta, ga, usa
Re: Why am I loosing boost after VTEC? (xPRELUDEx)
Hello,
Cam timing and profile can effect boost levels with a turbo or supercharger but more so w/ a turbo as there is back-pressure in the exhaust manifold. When the cam is changed, as wiith V-tech kicking in, the bost will vary. This change in boost does not mean that the turbo or supercharger is not doing it's job. Boost is simply a measure of back-pressure in th intake manifold. If the intake cams have a shorter durationand/or lift then there will be there will be higher manifold pressure and lower pressure in the cylinder. If cams have a longer duration and/or higher lift then there will be a higher pressure in the cylinder and lower manifold pressure or boost. If the engine feels like it is contiuing to make power as the boost drops off w/ v-tech then you are better off. Because if you can produce the same level of power with less boost then you stand less chance of engine damage because of detonation. In some ways boost (measured as manifold back-pressure) is actually the enemy.
HTH,
A K
Cam timing and profile can effect boost levels with a turbo or supercharger but more so w/ a turbo as there is back-pressure in the exhaust manifold. When the cam is changed, as wiith V-tech kicking in, the bost will vary. This change in boost does not mean that the turbo or supercharger is not doing it's job. Boost is simply a measure of back-pressure in th intake manifold. If the intake cams have a shorter durationand/or lift then there will be there will be higher manifold pressure and lower pressure in the cylinder. If cams have a longer duration and/or higher lift then there will be a higher pressure in the cylinder and lower manifold pressure or boost. If the engine feels like it is contiuing to make power as the boost drops off w/ v-tech then you are better off. Because if you can produce the same level of power with less boost then you stand less chance of engine damage because of detonation. In some ways boost (measured as manifold back-pressure) is actually the enemy.
HTH,
A K
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