im a newb to forced induction and Im in the process of tuning my first turbo build. Well, the fitech TB computer is doing the tuning for me, but i cant seem to get the boost up where i want it .
Quick rundown of what im working with,,,,,SBE 6.2 LS3, 317s ported by me, Bullet turbo cam (225-229 at .050, 585-585, 114 LSA installed +2), 9.12 to 1 comp, Holley single plane intake, CXracing turbo headers, homemade stainless plumbing to turbo (front mount), fitech 1200 TB, CXracing GT45R 80mm turbo (80-108mm comp, 77-89 turbine ) 1.15 AR, turbosmart hypergate 45mm wastegate, innovate SGC-1 controller, CXracing A to A 29x12x4 innercooler, 2 1/2 in hot side, 3 in cold side, 6x9 S&B cone filter. Right now the timing is set for 13* at 12 psi, tapering down 1 1/2* per psi from 31.* at zero boost. AFR is at 11.5 under boost.
my plan is to wind up at 12 psi on pump 93. so far I havent had a chance to stretch it out past just into second gear, but im only seeing about 6 lbs of boost and thats in first gear. the boost drops back to about 4 lbs when i shift to second and Im out of room on my little straight spot in the road at the end of my drive. My trans is a 2004r with a 2800 stall, rear gears are 3.42, tires are MT SS 305/35/18s (26.6"). I cant get into boost sitting still, power braking (still showing 2 or 3 in of vacuum, up on the converter) so im probably 10 ft out before it gets to positive pressure. 3 seconds later im at 6800 rpms, 60 mph, 6 psi and shifting to second.
After that long winded description (sorry), my question is, how quickly should I expect this setup to build boost ? Should it hit my 10 lbs wastegate pressure in first, or am I getting through first before it has a chance to build ? I plan to go to the track in a couple weeks to dial it further, but i will most likely take a ride to a better "street testing spot" in the next day or so to see what it does if I hold it through second gear.
Anyone else noticed how much boost they make in first and do you have any advice on whether my setup is on the right track ?

 

Converter sounds a little tight. Be sure to check for any boost leaks. You need to gather a little more data before drawing any real conclusions.

 

Not having lots of boost in first gear is a big plus sometimes. With 14 PSI in first, I still can't get traction at the track with slicks or ET Pros.

Get some real data for the other gears to find how boost is settling/creeping before you jump to any conclusions.

 

Come on Joe, we all know you make huge power, YUGE, but we also know that Novas can be set up to handle it! Get some suspension under that thing!!!!

 

Yea, the converter is tight.It was speced for the car NA with different heads, cam, exhaust, and intake. It worked good with the tight lobe cam that use to be there. Now im down probably 30-40 ft lbs NA at the bottom of the revs. About 10 ft out, its a different story though, LOL. The car hooks dead on the street and gets motivated pretty quickly after that. I took it out this morning with intentions of holding second gear for a few seconds. Evidently, the dew wasnt all off the road yet . I couldnt keep the car straight enough to stay in it in second. it got out of shape in first but I drove through it, thinking second gear would straighten it out some. I guess that works better NA, LOL.

 

This hooking close to 8 second power on the street from a 1st gear roll

 

I believe any engine should come to at least 0psi up on the converter, with or without a turbo. It could be a restrictive filter, a restriction somewhere else, a throttle valve issue (not full travel), bad gauge/connection/location,

I would inspect for boost leaks no matter what. And def check the throttle is opening all the way. then ask myself where is the gauge reading from? And probably try a different gauge.

Vacuum is showing you a restriction in the engine. For example, if you removed the intake manifold completely and started the engine, that would be 0psi. The reason you get less than 0psi on an engine at idle is because the throttle valve acts like a restriction, so you see vacuum in the manifold instead of 0. Anything less than 0 is showing you that same kind of restriction in play.

 

i cant get to 0 psi without breaking the tires loose. The brakes wont hold it, so i believe its a tight converter. like i said in an earlier post, the converter wasnt speced for a turbo.
Kingtalon does bring up a possible issue though. The filter could be an issue and I do have a turboguard i plan on using at the track. Next time out, I will pull the filter and see what difference it makes.
As far as the gauge location and accuracy goes, BOTH gauges read at the intake manifold, so im sure there is a percentage of lost boost through the innercooler and piping. CXracing claims less than 1 psi loss at 15 psi, but ocean front property is cheap in Arizona too. i am getting 100% on the TPS at full throttle and the SCG 1 controller and the mechanical gauge are reading the same.
i can get the boost gauge to 0 to 1 psi if I really try, but it breaks the tires loose against the brake as soon as it gets there. This happens at roughly half throttle, holding the brakes as tightly as I can.
Thanks for the input everyone.

 

You should be able to light that turbo off quick with an LS3, even with a tight converter.

Might make sure the WG is staying closed. Do you have a valve of some sort inline between the gate and the pressure source? Check for other leaks? Could also just be really bad brakes. What do you have for brakes on the rear? Pad type?

 

A lot of people will mistake a loose converter for a tight converter just because their brakes are terrible and they can't get it to hold on the line.

 

I have 13" rotors with 4 piston calipers on all 4 corners and although Im still working the air out after a booster and master change, they stop better than a 72 Camaro should. as far as waste gate control goes, I have the Innovate SGC-1 boost controller. Right now I have the controller start pressure at 11 lbs so it doesnt have any influence over the boost pressure. I need to know what the 10 lbs spring makes before I can set the controller up.
I took the car out yesterday evening to another spot to wind her up a little. It made 6.7 lbs in first, dropped to 4.2 lbs when I hit second and never got past 5.2 lbs in second gear. I ran it up to the shift light in second. My son asked me if I thought the blow off valve could be opening under boost because it has a different sound these days. Its a "real" HKS SQ4 BOV. I did a ton of searches on the HKS last night and didnt turn up much in the way of valve opening under boost problems, but who knows ? I made a "test" pipe to eliminate the BOV, but Im going to do a leak test on the system before I try it. Unfortunately, I dont have a 220 plug in my garage since we moved, so I cant fire up the compressor for an air source. I will make the 15 mile trip to the big city at some point today and fill up my air tank so I can put some pressure in the system and see if my welding is up to par.
Thanks again for the input ! Stay tuned.

PS...Last nights pull was without the filter in place, just the turboguard. Didnt see much if any difference in boost pressure either way.

 

Does that WG have a fire ring? My buddys car did the exact same thing after he forgot to put the fire ring in. Actually he didnt know it had 1, he sold me the turbo and WG and i asked him wheres the fire ring. He was like what? We finally found it in 1 of his boxes with the BOV flange he didnt use.

In short id check the WG and make sure its got a fire ring

 

Are you talking about the valve "seat" ? Im pretty sure you are, and , yes sir, the seat is installed.

 

thats it, some ppl call it fire ring some call it valve seat.

 

What pads are you using on the rear? VAC assist? Get all the air out of the system for sure. I found the cheapie soft organic style parts house pads are much better at initial holding. The nice aftermarket pads need a bunch of heat in them to get grabby. You can extend the brake pedal too, made a surprising difference when we did it.

 

Not 100% sure on pads. They came with the brake kit. The company didnt brag about having hipo pads , so I assume they are pretty generic. I dont have any vacuum assist, just a one way booster fitting. The cam holds 15-16 in of vacuum at idle.

 

Get a cheapie air regulator with a low pressure gauge on it and hook it up to the line going to your wastegate. Hook air compressor to regulator. Crank air up until gate opens, check gauge.

There seems to be a LOT of people who never test their gates and then don't know why boost is doing what it does. A buddy of mine JUST had this problem. Put what he was told was a 14 lb spring in his gate, cranked the manual boost controller ALL of the way in and it would spike to 14 PSI and then drop to 5. He finally took my advice and tested the gate, its a 5 lb spring. The exhaust pressure was forcing the gate open from the back above 5000 RPM.

Moral of the story? Test your gate.

 

So you have no accumulator on the system at all? Do you have a brake bias valve? Could you tap the system and see how much pressure you are actually getting in the rear? You won’t get much holding power without an upgraded ratio master, long pedal, and serious foot pressure. I’d look into some sort of VAC assist if really want to foot brake the car. Might try a cheapie set of autozone pads in back too.

With junk pads on all 4, Stock accumulator (with min vac pump assist), longer foot pedal and some serious foot pressure, I could hold around 600 hp and 30lbs of boost on the foot brake with factory single piston calipers on all 4. (10 sec 4cyl car). DOesn’t take a million dollar set of brakes, just the right cheap modifications.

 

When I think of boost in first, I think of a rolling start. No brake at all. This is a kind of, generic, standard. Put it in first, let the car roll, then smash the pedal and log boost pressure. The weight of the vehicle, gear ratio, weight of rotating assembly, and torque of the engine will mostly determine the rate of change of engine RPM which is basically how long you have to build boost.

For example, if you rev the engine is neutral, the rate of change is too high, there isn't any load from the drivetrain/tire/weight so you cannot expect to see high boost.

Likewise, if you hold the RPM steady using a load dyno, whatever RPM you want, and go full throttle, you can see how much boost is possible at that RPM, because RPM will not change (zero rate of change).

try to imagine this and understand what the rate of change of RPM has to do with boost pressure and it should make understanding the other aspects of why and how easier.

 

To test the gate do I need to remove it from the turbo system ? which line going to the gate do I apply air pressure to. My boost controller has a line going above and below the diaphram. can I check the gate spring when I pressurize the whole system while I check for leaks ? sorry for the dumb questions. Like I said earlier, I just got my boost badge on this car and Im still in the early learning stages.