RX7Store GT35R Boost Creep / Need a new manifold ??
 

Guys,

Got a GT35R Kit from RX7 Store

Attachment 753368

Attachment 753369

Made 360 WHP @ 16PSI on Dyno with Nelson Siverio tuning my Haltech PS1000 with all supporting mods on Stock Ports / Road Race FD / almost open exhaust.

But next day at the track Boost spikes were all over the place and got into Limp mode at least 4 times for boost spikes over 21 PSI.

Is this a manifold / 44mm wastegate location related issue ??

Or a Boost Control issue on my Haltech EBC ??

Shoud I get a new double WG manifold maybe ??

Please your feedback....!!! Don´t want to spend thousands on parts that won´t fix my issue...

Thanks...

The Tial 44mm (MV-R) should have no problem managing that boost if the WG runners are properly placed. I ran my PT6265 with a single MV-R along with an A-Spec manifold and it had no problems holding boost at 19-20psi.

You can only see how one of the WG runners connects to the manifold, but from what I can see it looks like that runners placement is giving STRONG priority to the turbo, instead of allowing the WG to do it's job... The angle that your manifold runners meet at looks to be completely backwards with regards to allowing flow towards your WG...

For comparison sake, here is my manifold with pictures of both runners:

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First thing to check on those ebay manifolds is that the hole in the turbo runner is opened up to the full size of the wastegate runner. Often not the case on those.

Sometimes you just need to grind a smooth transition to the wastegate runner entrance (part of the opening closest to exhaust port). Conversely, its best to leave the upper part at a sharp angle to turbo runner flow.

You can exaggerate this effect by cutting the manifold runner down toward the exhaust port at the wastegate runner to turbo runner "crotch" and welding in a pie piece for a smoother "teardrop" entry.

That wastegate runner placement/size isn't high wastegate priority, but its far from the worst I have seen.

Next is to check the wastegate itself.

If it is an ebay Tial knockoff it could be a damaged diaphragm or poor tolerances/materials on the valve or valve body/guide or incompatible materials causing the valve to weld to the seat momentarily.

Wastegate is the real deal... 99,99% Sure...

Actually when EBC is disconnected WG can hold spring pressure with no problem...

So your issue is with the EBC, the EBC settings or how the hoses are hooked up!

I personally hate boost controllers. I prefer to run off a waste gate spring. It's one less failure point that can cost you a motor.

Yeah, me too.

However, when you want to run pump gas/low boost for street and then high boost/race gas for racing-

a boost controller is easier than swapping out springs on wastegate(s).

I bullet proofed a Hallman Pro-RX with -an fittings and lines back in the day and now they even offer -4an fittings on the Hallman Pro-RX so you don't have to re-thread your manual boost controller.:icon_tup:

Using an EBC can bring in boost quicker as well. You need to review your bc settings with the tuner. You are getting into a situation that is driving the boost spike. For instance maybe your ebc was tuned in 3rd but now hit 4th on the track. Its all in the settings.

what size dump and exhaust?

^THIS

I got frustrated trying to set the closed loop EBC on the haltech, and went the easy route by setting it as open loop (sure, max boost varies with the weather, by 1-4 psi). With closed loop, I was getting boost spike when shifting at WOT (not at redline prior to shifting), and gave up trying to figure it out on the street/public roads.

you can use a generic duty map (boost vs rpm) in haltech to control the boost solenoid.. you can make whatever boost curve you want, closed loop. most aftermarket boost controllers are crap

Car was tuned on 4th gear pulls, and boost creep always happened on 3rd Gear redline to 4th gear.

All wastegate lines ar braided AN I guess if EBC was able to hold 16PSI on dyno 4th Gear conditions, it should be well plumbed.

Dyno Video

Just spoke to tuner and he thinks he can get it better, so we´ll do some 3rd gear pulls and find out if I can still use the single WG manifold...

Hope so... Got another things I need to put my money on...

Thanks a lot..!!

The dyno will sometimes load the engine differently than what you will on the road. This will effect boost response. If you have some logs of the car on the track showing MAP and boost controller duty cycle you can go back and make adjustments. The 3D base duty cycle map in the Haltech should be setup to give close to optimum results in open loop control so that once closed-loop is enabled the ECU has a good base reference of what DC should be. The closed-loop control then only has to correct for local ambient condition changes. Similar to tuning a fuel map and then running closed-loop. You wouldn't not tune the base fuel map or do it very roughly and then expect closed-loop to do the rest.

Nelson is one of the best, he'll get you sorted.

Does the haltech use the open loop boost map as a reference when using closed loop boost? Some day, I will play with close loop boost control again :lol:

It's called the start duty map. It's an optional map but it's the same idea as the open loop map. The Haltech boost control works very well. But everyone wants a PnP system that they don't have to put any thought into making it work. If you read the manual and spend some time learning the system, it can be made to work very well. It's just requires some understanding of how it works.

The Elite now has autotune capability on the boost control function, just like the fuel and ignition tables. It looks at actual boost v. requested boost and trims the start duty map for you.

Of all the ECUs I've worked with, Syvecs has had the best boost control. It's very complex and can do a bunch of stuff but the base settings out of the box just work, every time. Like Haltech, you have to build a base duty map but that doesn't take much time at all. From there, the PID control is just spot on every time for every boost level.

I know works, but those damn PID settings kicked my butt :lol: And that was after reading the haltech's manual, Crispeed explanation, and your explanation :blush:

Sounds like a tuning issue. I'm going to give the tuner the benefit of the doubt though and say that, without a customer paying for a certain number of street tuning hours, it's really hard to get it right. I'm not sure what OP's arrangement was with the tuner. Dyno is good but it needs street/race time.

If you're banging through gears and getting spikes, first you have to look at the logs and see whether the spikes correspond to the duty cycle curve moving too high. Disable closed loop and see if it goes away (set gains to 0 or whatever method you choose). If it's a closed loop issue, tou can clamp down that behavior with the delay timer, the start pressure, or the target map. Without air temp compensation it gets a little annoying. When winter rolls around the system wants to spool much faster.

There is a whole sequence to tuning closed loop boost control. It depends on what standalone you're using. For a simple PS1000 with just a target boost table, PID gains + delay timer & start pressure setting, with closed loop base duty table:

1) set all the closed loop gains to zero and basically run in open loop. tune the start duty/open loop/baseline portion of the duty cycle first. Adjust this table until you are slightly below your intended boost level (you want 12psi and you tune to hit ~11 max) and tapering off a bit. Start by setting the whole table the same and ramping it all up and down in fixed increments, then fine tune smaller portions of the map.

2) (more than one way to do this part, follow your preferences) basically zero out the delay till control and control start pressure. Those settings are there to dampen oscillation and spiking and can be brought in later. Set a fixed boost target for the whole map to keep it simple. Adjust the P term first until the peak boost reaches target (we had 11psi, now we have 12).

3) Adjust I term to reduce dropoff at high rpms. Be very careful with I term as it can lead to spiking and "wind up" . It needs to be kept under control with the target table, delay timer and start pressure. At low rpms maybe you can't reach the target boost due to turbo sizing, so you have to be careful here. If the target calls for 10psi at 2000rpm and your turbo will never make 10psi there, the I component goes crazy trying to get to 10psi unless you contain it with the right settings.

Iterate the process as driving conditions change. It all starts with the correct open loop/baseline duty cycle map. Then it's a matter of containing the closed loop control so it doesn't run away from you. This basic process also works on systems with gear based and throttle based. Go WOT and pick a gear as your nominal condition to tune in, then use the gear and throttle based settings relative to that. For example, maybe cut boost and duty cycle targets down in lower gears to reduce wheelspin. Trim the duty and target maps at part throttle relative to what works at full throttle.

You just have to take this big picture and break it down into a series of smaller related tasks. That's often the hardest part for people new to tuning: the order of operations and knowing what to adjust next so you don't throw the whole thing off and chase your tail. As you get more experience you can see the big picture and it feels more and more simple and straightforward. This is the kind of stuff we talk about in the Rx-7/Power FC tuning group all the time.

or you could just simply run the wastegate to the compressor and see if it still creeps, which will eliminate the guesswork of the EBC settings causing it.