A brief synopsis:

2005 GTO w/ totally stock LS2 engine [stock springs/pushrods]
STS kit w/ fabricated Y-pipe [diff exhaust on ’05 vs ’04 goat]
GT40-67 turbo w/ .81 A/R
FMIC
Devil’s Own methanol kit
60# injectors
Walbro 340 fuel pump w/ hot-wires [and inactive voltage amplifier...for now]

The Tial wastegate has a .6 bar spring in it, which should mean 8.8 psi…figure 1.5 psi loss through intake plumbing and intercooler, a solid 7 psi at the intake manifold. I see this on the road…but tuning on the dyno is a bit different.

Dyno Issues:

Tuned @ RWTD on Dynojet that produces a load. During the first round, a 5% load was only showing ~5psi, even though I see a consistent 7 psi on the street. We tried load settings between 10% – 15% but would watch the boost move momentarily to 7, but then drop back to 5. The air-fuel [measured on the passenger (more lean) side was 11.5-12. This produced these numbers w/ 17* of timing. The graph is interesting in that the torque curve is lower than several previous runs, as we’d lowered the load setting. For comparison, I have also included another run, where we were getting KR which lowered power in the upper range.




So, not exactly thrilled at thrilled with these numbers (and also realizing that I wasn’t producing full boost on the dyno) we turned on the boost controller.

STS uses a simple electrical switch to open a solenoid. This allows pressure from the wastegate pressure line to be fed to the back-side of the wastegate, in effect increasing the wastegate spring. There is a 0-5 psi manual valve that controls how much pressure is added to the spring pressure (and I realize that most of you understand this stuff!).

Why mess around? I opened the valve ALL THE WAY, thinking I wouldn’t possibly see more than 10 or 12 psi…

I’m watching the laptop, monitoring KR. John is doing the run, watching the dynojet display, mostly for air-fuel. My buddy Chris is watching the boost gauge. During the first high-boost run, with NO KR seen by me, Chris yells at John who shuts it down. It seems that the car built boost smoothly to 10 psi and then JUMPED to 15 psi, and sat there! This is run #16

So, I turn the boost gauge down some, but it was still showing 13+ psi, and we shut down early again (but again, no KR).[Run # 17] BTW, you will notice that the AFR's are a bit richer @ higher boost...that's the methanol injection kicking in. The pump was NOT connected at the lower boost run.




There is no question that the engine would NOT have liked us to continue those runs…but it is mind boggling to me to see those numbers on a totally stock LS2 engine w/ fuel upgrades.

But, we soldiered on, hoping to get some nice numbers, safe boost, and full rpm range. As we lowered the boost controller and ran further out, the MAF started to throw all sorts of errors at us…turns out that there is a GM software problem, and the folks at HPT have been hard at work to resolve this. [We saw AFR spike to 18…pulled plugs, and all of the electrodes were still intact. Engine still runs fine.] As I write this, I am informed that it is solved. Mobile is a 540 mile round trip for me, though, so I can’t just “drop-in”…but we will get this resolved.

Finally, I want to show two graphs that track each other quite well across the lower rpm bands. What you see is the benefit of the boost controller, as it builds a LOT more boost as it revs. The switch will NOT be activated all that often...but it is there in an instant when needed!



Thanks for reading!


AND, let me add: thanks to John and James @ RWTD...lots of time in here, and a little bit more to go!

 

Yeah I'd real careful regardless of whether you are getting KR or not. Have seen 200 mile engines on brand new cars/trucks eat pistons with exsessive boost on the dyno. Nice numbers though

 

NO question!!! The game plan is to tune for 525-550 RWHP when all is said and done. It was just so bizarre when it ran up so cleanly...

...and, the IAT's were around 110deg, w/ >90 deg ambient air in Mobile! STS may have a bit of lag compared to a front mount, but you cannot argue w/ such low IAT's.

 

Argue or not with the low IAT's thats not what really keeps the motor together...LOL Rings are what cause pistons to fail moreso then a lean condition or KR. They squeeze together and take the piston with them. Seen it way too many times. That motor is on borrowed time.

 

I understand! And that's why I don't intend to operate it at that setting...I am NOT running the boost controller until we get the MAF 'patch' software in, and tune w/ more realistic boost (10-12 psi). Ringlands/pistons/rods fail due to too much BMEP...simply gets past the strength of the alloy. But, tendency towards detonation DOES relate to IAT, hence the AGGRESSIVE KR built into the LS2 computer. And detonation blows motors!

Read again: goal of safe tune 525-550 rwhp...when the boost controller is flipped. 450-475 more often [that is, without the boost controller]...motor will last just fine...but thanks for sharing!

On another note: a RELIABLE boost controller that could be mapped for boost vs. rpm would be interesting. Let it run the 15 psi up to 4200...gradually bring it back down to keep the hp in the 550 range, but broadening the torque curve...

 

I'd recommend running the boost ref line form the wastegate up to the intake manifold. I did that with mine after the intercooler install and it keep the boost numbers in line MUCH better. I also have had issues with the air regulator they sell doing just as you described, it seems to "sticks" closed and then all of a sudden pops open and over boost. That's why I'm staying in low boost (7 lbs) till I get a more reliable boost controller.

 

Thanks for the info. Referencing the pressure up at the intake manifold is an interesting thought, might run a line just to play with on the street. As far as the pressure regulator, I am not sure why in the world it should act like that, as it should be an accurate device. Once set, it should reliably only allow x psi of boost through.

Trouble is...what is reliable? I see Jose pushing the eboost2...and then hear of problems with it from other folks. Greddy...lots of problems out there...

Another interesting thought is the homemade controller another fellow on here made using brass check-valves. I have a 'cut and paste' of the info, but cannot give credit as I don't have the poster's name.

I still like the idea of the solenoid controlled switch. Engine will last a LOT longer running just modest boost in that 450-475 rhwp range, and pushing the switch when necessary!

 

I would be intersted in seeing this controller setup.

 

nice #'s...

 

I never said KR wouldnt kill a motor. But excessive cylinder pressure will far surpass the KR on stock pistons. With KR under control & A/F ratio; Cylinder pressure will kill a stock piston and ring set faster then anything.

15 psi down low and droppign back wont help much either....15psi anywhere still creates alot of cylinder pressure anywhere in the curvewith a stock cam. Something you do want with a good cam is to relieve cylinder pressure alot better. That will aid some.

 

nice numbers

 

We figure that on my Mustang Chassis Dyno that stock LS pistons seems to handle approx 500 rwhp under boost before #7 cracks, even when no knock is detected. The larger LS2 ci can probably withstand a little more rwhp.
The Mazda RX7/LS1/ATI ProCharger D-1SC that we did is at 563 rwhp on my Mustang Chassis Dyno, which is living on borrowed time.... This car is being dropped off tomorrow for us to add Sanderson headers. Only time will tell.... Bob

 

For a long time I wanted the STS system for my LS1 GOAT, but decided NA was the way to go to avoid concerns of detonation, and boost issued like these. I spent $7,500 on mods H/C/E etc, and am running 485 at the flywheel. How much was your STS/ install/ tune price?

 

i realize you have experience, and i respect you, but come on...

 

Torque is a huge factor when comparing going high end na setups to boost. You might get close na as far as hp but torque will be alot lower.

 

those are some good numbers...my 02 WS6 made 480 rwhp and 520 rwtq.

 

Can you give some details of your set up, boost ,etc?

 

ill pm you the info.

 

pm sent

 

A 5 year old thread bumped alive again. Great job