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2002 chevy trailblazer_ls
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219 Posts
$900 isn't bad at all, but it doesn't *LOOK* like it would flow that well and it doesn't leave much room for the rest of the piping...though i've rarely seen a turbo'd car that had any room in the engine bay anyway.
 

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gmc
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830 Posts
$900 isn't bad at all, but it doesn't *LOOK* like it would flow that well and it doesn't leave much room for the rest of the piping...though i've rarely seen a turbo'd car that had any room in the engine bay anyway.

From first hand experience with the manifold, it flows very well. The transitions from the runners to the plenum are quite gradual. After 6 months of usage I have no hot spots in the coating which would indicate a flow problem.
 

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2002 chevy trailblazer_ls
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219 Posts
tubing is easy, 120 mig welder and parts from autozone will take care of that if you're desperate. Good to know it flows well, that takes care of alot of people's concern. You're running megasquirt, right efi-diy? that eliminates alot of forced induction problems, but there's still no work around for a stock ecm right?
 

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2005 gmc envoy_sle_xuv
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419 Posts
There is a work around for the stock ECU, some guy tried it, reported he got it working, then screwed. No one knows where he went.

You need to upgrade the MAP sensor and scale tables pretty much. If I recall correctly in order to use Megasquirt you had to change around some engine components?

Either way if you want it to work, it will in the long run. But don't expect to go crazy cranking up the boost on a stock block
 

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2003 chevy trailblazer_ls
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1,248 Posts
I'm not sure that there is room to expand the air flow enough via the MAP tables. While we can enter any figure into the table that we desire, getting the actual performance from those entries is another issue. Just not enough air and fuel flow capability (our system is close to maxed out, as I gather from around a year of investigation).

For turbo use, a MAF would be a better way to go, I think. Measure actual air flow versus trying to scale MAP above atmospheric levels. Ignition could probably be handled by the Ford ECCV computer -- more tunable than the current GM offering -- especially for boost-level output.

Placement of the MAF (needs scaled linear air flow) is critical, and it probably needs to be in a straight-line section of intake tube, and then carefully calibrated via wide-band O2 sensor and dyno data, with appropriate tables drawn for the PCM.

Just a few thoughts I've had in regards to tuning the turbo 4.2. I REALLY wish it were easier, but alas, it is not. I'd do a STS remote in a heartbeat if it were, but the cost of the kit will at least double before you end up with a drivable (if ever) vehicle.
 

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gmc
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830 Posts
tubing is easy, 120 mig welder and parts from autozone will take care of that if you're desperate. Good to know it flows well, that takes care of alot of people's concern. You're running megasquirt, right efi-diy? that eliminates alot of forced induction problems, but there's still no work around for a stock ecm right?
Yes I'm running megasquirt. I'm not an expert on the GM PCM's so I hesitate to comment, Erik supplied a lot of info to another member who claimed to get it working by rescaling the map tables etc. Best to let Erik chime in.

The stock block/rods are good for 10 PSI with a proper tune up that is what I ran on my stock 4200 without any issues.
 

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gmc
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There are 36# injectors available that fit the stock fuel rail - I ran them on my stock 4200 turbo install. So fuel isn't an issue.

I'm not sure that there is room to expand the air flow enough via the MAP tables. While we can enter any figure into the table that we desire, getting the actual performance from those entries is another issue. Just not enough air and fuel flow capability (our system is close to maxed out, as I gather from around a year of investigation).

For turbo use, a MAF would be a better way to go, I think. Measure actual air flow versus trying to scale MAP above atmospheric levels. Ignition could probably be handled by the Ford ECCV computer -- more tunable than the current GM offering -- especially for boost-level output.

Placement of the MAF (needs scaled linear air flow) is critical, and it probably needs to be in a straight-line section of intake tube, and then carefully calibrated via wide-band O2 sensor and dyno data, with appropriate tables drawn for the PCM.

Just a few thoughts I've had in regards to tuning the turbo 4.2. I REALLY wish it were easier, but alas, it is not. I'd do a STS remote in a heartbeat if it were, but the cost of the kit will at least double before you end up with a drivable (if ever) vehicle.
 

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gmc
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830 Posts
There is a work around for the stock ECU, some guy tried it, reported he got it working, then screwed. No one knows where he went.

You need to upgrade the MAP sensor and scale tables pretty much. If I recall correctly in order to use Megasquirt you had to change around some engine components?

Either way if you want it to work, it will in the long run. But don't expect to go crazy cranking up the boost on a stock block
Well Megasquirt does not support drive by wire so the TB needs to be changed to a early LS1 type. You also lose VVT cam control ( at least right now). For a TB install if the tuning can be sorted out the best to stay with the GM PCM.

MSextra code will work off of the stock GM crank trigger so at least that issue is gone.
 

· Northwest Chapter
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OK, so for those of you that may be new or have missed the past discussions, the ENTIRE problem with the 2002-2005 I6s with the P10 PCM and no MAF is that once the PCM sees above 1 Bar of pressure at the MAP sensor (its actually the voltage the MAP sensor sends to the PCM, cant remember if its maxed at ~4.7 volts or at 0 volts, think 4.7 though) the PCM throws a code for MAP range error and puts the engine into Reduced Engine Power mode. Which means you cant really do anything.

The hardware part of a turbo setup for the I6 could be done easily, thats not the issue at all. We now even have the Steedspeed turbo manifold that makes it even easier to bolt a turbo up. BUT, here is where the hold up comes. The P10 doesnt have a big enough aftermarket (aka only the GMT360 from 02-05 uses it) to warrant either EFILive or HPTuners to code a custom OS for 2 Bar. Couple that with the complexity of the code that the coder at EFILive says takes forever to track down simple things, trying to make room in an already full flash memory space just simply will never happen.

Also, the P10 being MAF-less meant GM designed a hybrid Speed Density/alpha-N fueling algorithm that is really weird compared to either a true SD or alpha-N system. Basically it means the Spark tables are RPM and MAP referenced while the fueling VE tables are RPM and load referenced. I have yet to figure out how the load value is calculated and until someone does, there is simply no way to do it. And all of the tables would have to be halved in resolution because you need a 2 Bar MAP sensor to run a turbo without blindly guessing your spark and fuel. So you go from like 13 rows down to 4 or 5 (the way GM set the tables up they do not increase linearly).

I looked hard at performing a P12 PCM sway from an 06 I6 as it is the same ECM used in the Cobalt SS/SC and the Ion Redline S/C. But again, there is a difference between an 02-05 BCM and 06-07 BCM (and probably another one for 08-09 as they use another different ECM and TCM) that would not allow an 06 P12 to interface with an 02-05 P10 BCM as far as I know and have been told.
I would love to have someone figure this out, anyone in the Seattle area have an 06 I they'd like to let me borrow for a day?

So everyone who is still reading will ask, what does this all mean?
Simply put, unless you use an aftermarket system to control the spark and fuel after 14.7psi or 1 Bar of pressure, there is no way currently to run boost on an 02-05 I6 using stock GM electronics.

That said, 06-09 4.2L I6s WOULD BE EASY TO DO. Buy the Steedspeed manifold, a turbo, an intercooler (or meth injection), some bigger injectors, the plumbing you'll need, and get a good tuner in the loop (someone local). Ive said this more than a few times now, every single 06-09 I6 could be tuned in a day to a few days by an experienced tuner to run a turbo or supercharger. The PCM (06-07) and the ECM (08-09)s used in them accept boost easily, heck the P12 (06-07) runs it easily on the Colorado I5 turbo and s/c kits and the E67 (08-09) runs the 2009 Cadillac CTS-V 6.2L LSA factory supercharged engine. All the tables are there in the stock OSs for 06-09 trucks, someone needs to take the plunge and go for it.

That is some of the knowledge Ive found out about the P10 after tuning it for 3+ years now, but the likelihood of me ever pursuing it any more for personal reasons is all but done considering my 02 I6 will be gone by year's end in all honesty and my SS with the E67 (hmm look, same ECM as the 08-09 I6s has...) is easy to supercharge.

And as for the fellow that I gave all the above info to, he says he got his 04 I6 running on a 2 Bar MAP sensor and was going back in for the turbo install. Never heard back from him since then, and honestly just getting the MAP sensor in now isnt an issue. Thats simply scaling the spark tables and maybe tweaking the VE a little, not very drastic compared to actually bolting a turbo up and trying to compensate for the added airflow. I know lots of people wont want to even hear me mention it, but I think the next step is seeing if you can use the MSextra code to control the motor's fueling and spark once the stock PCM maxes out (and put a voltage clamp to stop the stock MAP from reporting anything over 14.7psi = no REP light).

To glfredrick, while Fords ECMs might be better on paper for running boost, tuning support for the entire Ford lineup is severely lacking. Between EFILive and HPTuners, GM's ECMs are much more capable. The E67s are the best we have the potential to use (they support both CAN and VPW comms while the E38 does not) but the P12s are a solid choice too (and can control both engine and trans, the E67 you need a T42 as well).
 
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