Synapse Wastegate question
Thread Starter
Joined: Sep 2004
Posts: 2,552
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From: Visalia, California
Synapse Wastegate question Hey guys, I'm having a boost creep issue every time I go into second gear (which I guess is somewhat typical). This thing has some tall *** 3.25 gears in the 9", a fair amount of converter, and a turbo 400. I just got some 28" et street S/S tires hung on the car yesterday and am doing some datalogging with a map I've been working on. I have the turbosmart dual stage wastegate and have both ***** unscrewed all the way (lowest boost setting). I have the vacuum line wired to 'Port C' as shown in online documentation. I do realize ports C & D together are my lowest boost setting, so I'm guessing there is no harm in installing a Y and going to both ports with this boost controller.
I'm hoping someone has been there, done that. I'd like to get this thing set up initially ~10psi (on catpiss 91, no meth yet) and work my way up the MAP, right now it's hitting 14psi only when I get into second gear and it pulls the motor down to ~5200rpm. This turbo is an 11-blade billet wheeled S475 on a T4 83mm turbine. Thanks guys!
I'm hoping someone has been there, done that. I'd like to get this thing set up initially ~10psi (on catpiss 91, no meth yet) and work my way up the MAP, right now it's hitting 14psi only when I get into second gear and it pulls the motor down to ~5200rpm. This turbo is an 11-blade billet wheeled S475 on a T4 83mm turbine. Thanks guys!
Last edited by 67Firebird455; Mar 19, 2016 at 09:17 PM.
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Joined: Mar 2014
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From: Ohio
What is your wastegate spring pressure?
Bypass the controller all together. Go grab some rubber line from the parts store and do a 2nd gear pull again. Don't blame the controller until you get results without it.
Bypass the controller all together. Go grab some rubber line from the parts store and do a 2nd gear pull again. Don't blame the controller until you get results without it.
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
I'll definitely give that a shot this week, thanks Joe.
You're kidding me. =( That's a bum deal, before this, I'd ran turbosmart on another car I had and it worked great but got talked into this one. Appreciate you guys responding!
Last edited by 67Firebird455; Mar 21, 2016 at 11:07 AM.
45lb spring, but haven't touched the preload whatsoever. I'm not specifically blaming the controller, but possibly the port it's plugged into on the synapse. I wondered if I was still able to attach ports C & D as shown in the instructions for the 'lowest boost setting' with a controller like this turbosmart.
I'll definitely give that a shot this week, thanks Joe.
You're kidding me. =( That's a bum deal, before this, I'd ran turbosmart on another car I had and it worked great but got talked into this one. Appreciate you guys responding!
I'll definitely give that a shot this week, thanks Joe.
You're kidding me. =( That's a bum deal, before this, I'd ran turbosmart on another car I had and it worked great but got talked into this one. Appreciate you guys responding!
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
One thing I noticed looking back at the instructions is it mentions attaching the WG to a boost only source. Right now it's off of my vacuum block on a line of it's own, but is on the vacuum side of the throttle blade. I understand this can create a vacuum leak if the valve does not seat correctly, and have read reports of this causing the wastegate to function incorrectly. We've had such great luck with these freaking little wastegates on our DSM applications, I'd hate to not use one on my car.
Glad you are having luck with them in some applications. Diesel guys were using them when they first came out and quickly changed to more common brands, Tial, turbosmart, etc.
Tie port C/D together for with boost reference from the boost controller.(reference from manifold block, turbo compressor cover, some say this is quicker boost response and generally higher pressure as the pressure drop has occurred yet through the intercooler)
Tie port A/B together for pressure from the boost controller.
That way you will see more volume. I never understood overcomplicating such a simple system.
Tie port C/D together for with boost reference from the boost controller.(reference from manifold block, turbo compressor cover, some say this is quicker boost response and generally higher pressure as the pressure drop has occurred yet through the intercooler)
Tie port A/B together for pressure from the boost controller.
That way you will see more volume. I never understood overcomplicating such a simple system.
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Verdad Gallardo Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
Bypassed the turbosmart dual stage controller, same crap. Boost gauge is showing far less than the kpa reported in hptuners even with it connected to ports C and D.
PS - I verified the preload is backed all the way off on the spring. I still see as high as 198kpa in second gear then it settles down to ~180. Maybe I need to crack this thing open, make damn sure I've got a 45lb spring in it, or say the hell with it and get a turbosmart and call it a day.
I've attached the wastegate priority, as well as a quick hptuners log screenshot (I know it's too rich still, and no timing).
PS - I verified the preload is backed all the way off on the spring. I still see as high as 198kpa in second gear then it settles down to ~180. Maybe I need to crack this thing open, make damn sure I've got a 45lb spring in it, or say the hell with it and get a turbosmart and call it a day.
I've attached the wastegate priority, as well as a quick hptuners log screenshot (I know it's too rich still, and no timing).
Last edited by 67Firebird455; Mar 25, 2016 at 01:06 AM.
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
Off of this block. What's strange is I'm never seeing the boost gauge hitting near 15psi. I just made a test hit after driving it to work and only got 139kPa in 1st, and then went to 159kPa when I hit second and then settled back down to 144kpa before I let off. I'm wondering if when the pipes were aluminized and filled with rusty **** from not heating the pipes up properly got **** up in the valve. I need to take the wastegate off and get it apart and find out wth is going on it sounds like.
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Joined: Mar 2014
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From: Ohio
Take the line that goes into your vacuum block. Hook it up to a regulator and an air compressor. This is how I bench test my wastegates.
I hook a line into the regulator, and the outlet on the regulator into the vacuum block. I slowly turn up the regulator until the wastegate opens, and then check the boost gauge. You can do this same thing with the key on and compare the MAP reading in HPTuners to the boost gauge, and listen for leaks in the line going to the gauge. If you unhook the wastegate and aim it upwards so you can see into the discharge, you'll be able to see the valve open. This should help you diagnose pretty much all of your problems.
Off topic, what brake booster is that? I just ordered a Right Stuff 8" dual diaphragm booster for my 69 Nova and haven't got around to getting it hooked up yet. Having issues getting the arm to line up with the hole in the brake pedal, but was wondering how it stops compared to manual brakes. Slowing down from 140+ with squishy manual brakes scares the hell out of me.
I hook a line into the regulator, and the outlet on the regulator into the vacuum block. I slowly turn up the regulator until the wastegate opens, and then check the boost gauge. You can do this same thing with the key on and compare the MAP reading in HPTuners to the boost gauge, and listen for leaks in the line going to the gauge. If you unhook the wastegate and aim it upwards so you can see into the discharge, you'll be able to see the valve open. This should help you diagnose pretty much all of your problems.
Off topic, what brake booster is that? I just ordered a Right Stuff 8" dual diaphragm booster for my 69 Nova and haven't got around to getting it hooked up yet. Having issues getting the arm to line up with the hole in the brake pedal, but was wondering how it stops compared to manual brakes. Slowing down from 140+ with squishy manual brakes scares the hell out of me.
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
Take the line that goes into your vacuum block. Hook it up to a regulator and an air compressor. This is how I bench test my wastegates.
I hook a line into the regulator, and the outlet on the regulator into the vacuum block. I slowly turn up the regulator until the wastegate opens, and then check the boost gauge. You can do this same thing with the key on and compare the MAP reading in HPTuners to the boost gauge, and listen for leaks in the line going to the gauge. If you unhook the wastegate and aim it upwards so you can see into the discharge, you'll be able to see the valve open. This should help you diagnose pretty much all of your problems.
Off topic, what brake booster is that? I just ordered a Right Stuff 8" dual diaphragm booster for my 69 Nova and haven't got around to getting it hooked up yet. Having issues getting the arm to line up with the hole in the brake pedal, but was wondering how it stops compared to manual brakes. Slowing down from 140+ with squishy manual brakes scares the hell out of me.
I hook a line into the regulator, and the outlet on the regulator into the vacuum block. I slowly turn up the regulator until the wastegate opens, and then check the boost gauge. You can do this same thing with the key on and compare the MAP reading in HPTuners to the boost gauge, and listen for leaks in the line going to the gauge. If you unhook the wastegate and aim it upwards so you can see into the discharge, you'll be able to see the valve open. This should help you diagnose pretty much all of your problems.
Off topic, what brake booster is that? I just ordered a Right Stuff 8" dual diaphragm booster for my 69 Nova and haven't got around to getting it hooked up yet. Having issues getting the arm to line up with the hole in the brake pedal, but was wondering how it stops compared to manual brakes. Slowing down from 140+ with squishy manual brakes scares the hell out of me.
That's the one man, that 8" dual diaphragm unit works like a freaking champ, I had manual drums before and this thing with disc is night and day difference and really slows the car down big time. Does your brake pedal also have two holes like mine did? Manual goes in one, power goes in another, that should fix the alignment!
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Joined: Mar 2014
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From: Ohio
Yeah, I have the two holes. Unfortunately the Clevis is about 3/4" below the bottom hole for power brakes. The 67-69 F body and 68-74 X body were almost identical mechanically, so you have the same booster/pedal setup as me. I may have to use washers on both the brackets and booster at the top to re-angle it.
Fix the compressor, use it to pressurize your vacuum block. You'll know exactly when the gate opens, and what both the boost gauge and MAP sensor read at the time. Its a win/win.
Fix the compressor, use it to pressurize your vacuum block. You'll know exactly when the gate opens, and what both the boost gauge and MAP sensor read at the time. Its a win/win.
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
Yeah, I have the two holes. Unfortunately the Clevis is about 3/4" below the bottom hole for power brakes. The 67-69 F body and 68-74 X body were almost identical mechanically, so you have the same booster/pedal setup as me. I may have to use washers on both the brackets and booster at the top to re-angle it.
Fix the compressor, use it to pressurize your vacuum block. You'll know exactly when the gate opens, and what both the boost gauge and MAP sensor read at the time. Its a win/win.
Fix the compressor, use it to pressurize your vacuum block. You'll know exactly when the gate opens, and what both the boost gauge and MAP sensor read at the time. Its a win/win.
I'll definitely fix up that compressor and check everything out. I got the wastegate off and disassembled. Unfortunately, it felt like there was a burr on the valve up fairly far so the valve would hang up when opening. I smoothed it out, and reassembled it, now the valve slides up and down smooth, so hopefully that makes a difference. When putting it back together, I got greedy and snapped one of the bolts on the 2.50" v-band for the dump so, I've got to locate one and get it on so I can do some testing.
PS - The wastegate had the blue 'A' spring, as well as the red 'D' spring for preload.
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
Just got to try out the car again after taking the wastegate apart and getting rid of a burr on the gate. Seems to do a whole lot better believe it or not. Now on ports C&D, I'm seeing 7.1psi in first at 6400, and the second I go into second, it hits 9.1 and then settles quickly down to ~7.5psi. I can tolerate that. I have it running at 15º and it runs a hell of a lot better than 10º. I don't want to push my luck, and plan to retard down to ~12-13º in the 15psi range. I still haven't installed the alky control kit, I'm just having a blast driving this car for the first time in 13 years.