LS2TT

iTrader: (1)

427ci / twin GT28r71 / Internally gated / EVC 6 (newest model)
Boost holds rock steady on 8psi wastegate springs.

Went to the track and set the HKS at 10psi.. Results posted above. The stepper motor will not open the wastegates soon/fast enough and it overshoots the target boost. 4th gear shut the controller off due to a 13.5psi boost warning. Tried changing "sensitivity" on the EVC and it made no difference.

I'm looking at the Eboost2 and the AMS 1000. The AMS looks to be overkill for a 600-700rw street car that will only see the track a few times per year.

Any recommendations for these or other EBC's that will work with a fast spooling twin turbo setup on a big motor? I'm thinking I need a solenoid type controller to get the FAST (<.5 sec) response I need to stop these spikes.
Scott

z28mccrory

iTrader: (7)

Wow those are small turbos for a 427.

Earlier this year i bought an Incon kit with Gt2871r's and was told that anything over a 346 would make for a horrible pressure ratio... even a 370. I ended up selling the kit.

HUNTER02SS

iTrader: (24)

Why not use a manual boost controller? Alot less headache and they work very well.

LS2TT

iTrader: (1)

Regarding the MBC, I'm open to options but I'm afraid they will still spike if the valve is too slow. Since the turbos are small, I like the functionality of increasing the boost as efficiency drops to smooth the curve. I also have RPM, speed and TPS inputs so I can do some cool tricks for a street tire car.

I need something with a ramp rate or boost sensitivity that will allow the actuators to begin opening BEFORE the target boost so it doesn't overshoot.

We ported the **** out of the exhaust housings and the wastegates seemed to get the job done. I'd love to go to GT35s but the car is a C6 Corvette and there is no room without cutting the car up. I'd also like to go to external gates but again, the cats take all the room and they will not fit. So it is what it is, and it makes 625rw/700tq so the little turbos are getting the job done.

I just need a controller that will prevent the spikes!

HUNTER02SS

iTrader: (24)

I don't think a different controller is your problem. I think that the turbo's are just to small and the internal WG's are not allowing enough exhaust flow to exit causing your boost to creep or spike! To big of a motor for those small turbo's. A boost spike is usually caused by to small of a wastegate.

LS2TT

iTrader: (1)

Here is a log of the car with the controller off.
8psi springs - actual boost is 7.7psi max.

LS2TT

iTrader: (1)

I ran the car today with boost set at 8psi and building to 10psi after 5000rpms. Just as a test. The car made 8psi and then ramped to 10psi, as expected... but after the shift it still spiked to 11.5. So the boost controller is only looking for 8psi after the shift (<5000rpm) and it still spikes to 11.5?



Seems either the stepper motor is too slow or the wastegates can't bypass enough exhaust when the boost goes to 10psi.

I need a concrete test to determine where the issue is so I don't waste money on another boost controller that may or may not fix my issue. Any other opinions or ideas?

onfire

iTrader: (17)

I ran a 427 with GT2871R's for a year without any problems with a EB2. Had 8psi springs and it held 8-17psi steady without problems. Best was a 9.9 at 141mph at 17psi.

LS2TT

iTrader: (1)

Were you running T25 flanges with internal wastegates?
Any boost spikes?
Do any data logging?
Were you running dual solenoids on the Eboost2?

I ask because the spikes I'm seeing are so short <.5 sec that you might not catch them on a gauge.
But they still cause my car to go lean/detonate/pull timing.

If not, then I might be in the market for an Eboost2.
Thanks for the input.
Scott

LS2TT

iTrader: (1)

Another note.. The car went 10.6@141 at 15psi (spike to 17psi).
The 60' was a 1.98 and I saw a spike to 17psi on the shifts...
Didn't have my hptuners cable so I was scared to run it again.

subarubill96

iTrader: (9)

hit the nail on the head, changing controllers is just a bandaid for a bullet wound IMO. the car is screaming for external gates, or a stronger actuator but even then im not a huge fan of internal gates so my answer is biased.
a MBC might be better but your still not solving the problem just treating the symptoms.

LS2TT

iTrader: (1)

I agree 100%.. But there is just no room and I can't justify reworking the turbo system and cutting up a new car.
If I can find a bandaid that will let me enjoy the car, I can live cheating a 1000hp engine with a 700hp turbo system.

I just want to find the best bandaid available.

Johnv

I have a Greedy profec B II EBC and it works great no spikes just nice flat boost curve. has high /low boost setting and overboost warning which can be programed to reduce boost.

Was put onto them by a mate who runs a drift car, and builds and modifys jap race cars. said he had tried all sorts of different controllers and the greedy was the only one that wouldn't spike on his car.

onfire

iTrader: (17)

Don't get a MBC as it has no method to control spikes on a small gated turbo.

Yes to all above except the spikes. Use EB2 with rpm boost control and set a boost curve vs rpm instead of "all in by 3000rpm" like a mbc. It will make your car quicker by keeping the boost down at lower rpm with 427ci.

Just set up a LPE car last week at the track with 346ci and GT2871R's and a EB2. Car ran 10.3 at 138mph at 3000ft da at 15psi....with a 6 speed...ran out of injector....at a "real track" that car would go 9.9 at 142mph....at 3700lbs....

onfire

iTrader: (17)

But they still cause my car to go lean/detonate/pull timing.



That needs to be tuned out of the car.

onfire

iTrader: (17)

http://videos.streetfire.net/video/B...138_707206.htm

MosesMcgregor

iTrader: (16)

Profec B II here too.... doesnt have fancy features but it holds steady pressure and is easy to switch between a high and low settings