BW S475 + LQ4/Tick Cam...Is my 44mm Wastegate Too Small and Causing Overboosting??
05-12-2014, 06:11 PM
#1
BW S475 + LQ4/Tick Cam...Is my 44mm Wastegate Too Small and Causing Overboosting?? Hey guys, I just got my '74 2wd Blazer running after ditching the 4.8/TVS1900 setup for a turbo LQ4 setup. S475 T6 1.32 AR. The rest of the specs are in my sig.
The thing runs like a raped ape, air/fuel are dialed it, etc, but for some reason I can't keep the boost under control. Its at 5 psi by 2700-2800 RPM and will spike to 14 psi by 3800-4000 (at that point I have already lifted the pedal).
Even with the lightest spring installed {5#) on the 44mm wastegate, it will blow right past 5 psi without missing a beat. I drilled and tapped the compressor housing for the wastegate reference point. The 1/4" hose is hooked the the side/lower port, the upper port is left open as per instructions.
I took apart the wastegate and the diaphragm is perfect and the piston/valve moves/slides easily. Tested the wastegate with a hand held air compressor and confirmed it is opening and closing. I even stuffed a rag in the outlet pipe of the wastegate and when for a drive and the after the first blip into boost I pulled over and the rag was blown out of the pipe, so I know it is opening like it should.
So....unless I missed my guess, the wastegate is too small to control my boost levels, correct? My wastegate is placed on the merge just before the T6 flange entering the turbo.
Any help is thanked in advance.
The thing runs like a raped ape, air/fuel are dialed it, etc, but for some reason I can't keep the boost under control. Its at 5 psi by 2700-2800 RPM and will spike to 14 psi by 3800-4000 (at that point I have already lifted the pedal).
Even with the lightest spring installed {5#) on the 44mm wastegate, it will blow right past 5 psi without missing a beat. I drilled and tapped the compressor housing for the wastegate reference point. The 1/4" hose is hooked the the side/lower port, the upper port is left open as per instructions.
I took apart the wastegate and the diaphragm is perfect and the piston/valve moves/slides easily. Tested the wastegate with a hand held air compressor and confirmed it is opening and closing. I even stuffed a rag in the outlet pipe of the wastegate and when for a drive and the after the first blip into boost I pulled over and the rag was blown out of the pipe, so I know it is opening like it should.
So....unless I missed my guess, the wastegate is too small to control my boost levels, correct? My wastegate is placed on the merge just before the T6 flange entering the turbo.
Any help is thanked in advance.
05-12-2014, 06:31 PM
#2
Glad to see you got it going man, but definitely sounds like it Cable. Generally it is ideal to position the WG at the location you have it, but tilted at a 45º angle with the bottom of the valve facing the incoming exhaust, so in your case, the top tilting to the left (looking at the pic).
05-12-2014, 07:42 PM
#6
Well it sounds like everything is connected right, you tested the spring too. .. I hate to say you may need to rebuild the merge/wastegate entry to give the gate more priority.
A more restrictive turbine would be more forgiving of poor gate priority, but that 96, 1.32a/r is very free flowing, and your gate placement might not be cutting it.
I also agree that a single 44 is on the small side, im running twin 40mm
A more restrictive turbine would be more forgiving of poor gate priority, but that 96, 1.32a/r is very free flowing, and your gate placement might not be cutting it.
I also agree that a single 44 is on the small side, im running twin 40mm
05-12-2014, 08:06 PM
#7
I am thinking of adding a second 44mm to the first 90* bend of the crossover pipe coming from the passenger side manifold.
If I recall correctly, a vendor (past or currently) does their turbo hotpipe kits with a single wastegate on the first bend of the crossover pipe with great results/success.
I would probably try to leave the current wastegate where it is, and see how it goes.
Opinions?
If I recall correctly, a vendor (past or currently) does their turbo hotpipe kits with a single wastegate on the first bend of the crossover pipe with great results/success.
I would probably try to leave the current wastegate where it is, and see how it goes.
Opinions?
Trending Topics
05-13-2014, 01:21 PM
#10
I found a Wyntonm 60mm wastegate I forgot I owned. I am going to install it since I have it already on the passenger crossover tube. I should have time later this afternoon, maybe tomorrow.
Last edited by Ford_Assassin; 05-13-2014 at 01:44 PM.
05-13-2014, 01:49 PM
#11
This is what I was thinking. It's just one of those things. If you were running your setup at 15psi, I bet that gate works just fine. However, trying to control the boost all the way down to 5 psi is another story. It is either turn it up, or just try to put another gate somewhere else.
05-13-2014, 02:09 PM
#13
How do you have the lines to the WG plumbed. I see a barb fitting on the top port in the pic? Your not running boost to the top port are you?
If your sure the timing and AFR's are on point I'd drop timing down to 9* or so see if it goes higher than 14lbs.
My 50mm gate will regulate my small 1.10 AR t4 S475 down to 8-9lbs.
FYI... I'm jealous your T6 4.8 spools faster than my t4 5.3...
If your sure the timing and AFR's are on point I'd drop timing down to 9* or so see if it goes higher than 14lbs.
My 50mm gate will regulate my small 1.10 AR t4 S475 down to 8-9lbs.
FYI... I'm jealous your T6 4.8 spools faster than my t4 5.3...
05-13-2014, 02:18 PM
#14
How do you have the lines to the WG plumbed. I see a barb fitting on the top port in the pic? Your not running boost to the top port are you?
If your sure the timing and AFR's are on point I'd drop timing down to 9* or so see if it goes higher than 14lbs.
My 50mm gate will regulate my small 1.10 AR t4 S475 down to 8-9lbs.
FYI... I'm jealous your T6 4.8 spools faster than my t4 5.3...
If your sure the timing and AFR's are on point I'd drop timing down to 9* or so see if it goes higher than 14lbs.
My 50mm gate will regulate my small 1.10 AR t4 S475 down to 8-9lbs.
FYI... I'm jealous your T6 4.8 spools faster than my t4 5.3...
I don't own the tuning software, otherwise I might play around. It has seen as high as 18 psi when I first noticed the wastegate wasn't controlling the boost levels. Luckily it wasn't for more than a second before I lifted the pedal. That was around 5,000 RPM too.
I have a 6.0 LQ4 BTW, I think you might of mixed up the previous 4.8/TVS1900 blower setup I had previously.
