Rumor has it...8lbs on stock DME?

[makenzie71]

True or no?

I've read in two posts that the stock OBDII M52 DME can handle 8lbs without needing to be flashed. Of course I know this would not be ideal and I wouldn't see the full potential of my setup, but if it'll work it would allow me to have the car down for a shorter period of time and safely space the project out a little longer.

Ideally I want a setup that will be able to push 1bar. This would be suing two small internally wasted turbos from another application (something like Garrett CT12B's), a 36X6X3 FMIC, 2.5"/2.75" downpipe mated to the stock exhaust, and larger injectors...along the lines of 440's. I'm also told I should use a larger AFM in the absence of proper ECU tuning.

[Shuasha]

Rumors are just that.. if you value your engine, don't be a cheap ass.

[makenzie71]

matter of time and scheduling, not so much total cost. How would it damage my engine?

[tlmitf]

the stock computer is not tuned to see boost - therefore the timing and fueling values will be wrong.
This can lead to a lean out under boost, followed by detonation, followed by total engine failure.

This is not good, and not worth the risk.
If your doing this kind of work, get a $200 car to last you a few months while the bimmer is getting worked on.

[RRdawho?]

NO.

It's a rumor.

And it will damage your engine. Grenade and glorified coffee table waiting to happen.

[makenzie71]

the stock computer is not tuned to see boost - therefore the timing and fueling values will be wrong.
This can lead to a lean out under boost, followed by detonation, followed by total engine failure.

This is not good, and not worth the risk.
If your doing this kind of work, get a $200 car to last you a few months while the bimmer is getting worked on.

The only cars I've done N/A-T jobs to have had provisions built into the ECU's that allowed them to handle a moderate amount of boost. If this is something the BMW DME absolutely can not compensate for, then that would be the answer I'm interested in. Thanks tlmitf!

[RRdawho?]

The ECU does have adaptation capabilities, but only up to a certain extent, and certainly not into positive pressure.

[makenzie71]

Gotcha. I'll just make provisions to have the ECu tuned when I do the install...which brings me to:

How do you guys get the mapping done when it's a one-off job? Partially due to the fact that I like to do work myself, and mostly to the fact that spending $10,000 for just 350hp is obscene, I will not be using an off-the-shelf kit. Are there people I can call up and list my modifications and needs to and they whip me out a generic program that does the job or is it something where I need to spend a day on the dyno lettign them tweak stuff?

[325icintn]

Fuel would be the biggest problem. You must retune if you use larger injectors. I don't think you can raise fuel pressure enough to supply fuel for 8lbs of boost on the stock injectors. Plus, more fuel is your only safety margin with stock ignition timing, so you have no room for error. I would hate to run out of fuel with 8psi on stock ignition timing.

[makenzie71]

Is it possible to retard the timing a couple degrees to allow a wider margin for error?

[RRdawho?]

OBD-II ECU's there are only a select few people that are able to tune those ECU's.

Mainly Karl at AA, NickG, and Jim (there are others out there most likely but not as widely known)

All options are $$$ and I do not believe NickG does anymore custom tunes.

OBD-I however, there are solutions out there that are much more affordable.

[a32guy]

Gotcha. I'll just make provisions to have the ECu tuned when I do the install...which brings me to:

How do you guys get the mapping done when it's a one-off job? Partially due to the fact that I like to do work myself, and mostly to the fact that spending $10,000 for just 350hp is obscene, I will not be using an off-the-shelf kit. Are there people I can call up and list my modifications and needs to and they whip me out a generic program that does the job or is it something where I need to spend a day on the dyno lettign them tweak stuff?

Something like that. Email NickG or AA.

[makenzie71]

doing an OBDI conversion has been something I've entertained but not researched much. How involved a task is it? Is it just a matter swapping a few components or is it something that will have me gutting the car to pull off?

[325icintn]

Do a search. It's easy and much less than any standalone. Make sure you'll pass inspections in your state (becaue you won't be legal in the Fed's eyes).

[makenzie71]

I'd pass...it's all visual stuff here...no one would know.

So if I run an OBDI conversion I'd be looking at needing:

turbo (something internally wasted)
Oil line kit and cooling lines
manifold
Possibly an oil cooler
BOV
FMIC
550cc injectors
DME tuned for boost

Simplified, yeah, but like I said...I wouldn't want anything wild. I'd never run anything over 1bar.

[325icintn]

If you swap obd1, you can run the TRM kit which is around $5k including the tune.

[Juicy Double]

Maybe you're getting your rumors mixed up... common opinion is that 8 psi is the max the stock engine can take at stock compression ratio, maybe that's where you got 8 psi from...

[GodFather]

i've never heard anybody run 8psi on stock DME....max i've seen was 3-5psi, and they would lean out as they hold the boost....
OBDI conversion and chip tuning will be ur cheapest bet...
Also, i would love to see how you would mount 2 internally wastegated turbos on the stock pipes

Stan

[wulfgang]

This has nothing to do with adaptation capabilities of OBDII or sensing the amount of boost. The problem is much simpler: if you run out of injector pulsewidth or you flow more air than your MAF can sense, your engine will go bang. Likewise, if you flow more air than the top end of the DME's timing maps at a given rpm, your timing will likely be too advanced and your engine will go bang.

[RRdawho?]

big bang.

[makenzie71]

Maybe you're getting your rumors mixed up... common opinion is that 8 psi is the max the stock engine can take at stock compression ratio, maybe that's where you got 8 psi from...

It is possible...I will have to go back and re-read the threads.

Also, i would love to see how you would mount 2 internally wastegated turbos on the stock pipes

Using a joined manifold and a single gate. I'd be using something akin to the CT12B manifold found on the 2jz-GTE. I've decided I'll probably just go with something simpler, though...the world is full of larger, simpler, internally wasted singles...such as a Garrett CT26 which I have ample experience rebuilding and modifying.

This has nothing to do with adaptation capabilities of OBDII or sensing the amount of boost. The problem is much simpler: if you run out of injector pulsewidth or you flow more air than your MAF can sense, your engine will go bang. Likewise, if you flow more air than the top end of the DME's timing maps at a given rpm, your timing will likely be too advanced and your engine will go bang.

This is something else I think I've addressed with some thinking time today at work. First, it was never my intention to use stock injectors. I'll be using 440cc injectors, minimum, but will likely go ahead and get 550's. If I am limited to 8lbs, though, I shouldn't need them. I'll be getting in touch with Apex'I this evening and find out if they have any fuel controllers specific to the OBDII E36 or if the generic tuning an SAFC-II will do will suffice my project...a piggy-back fuel controller will handle all my duration/volume issues...I think. It has before.

[antonch]

Stock AFRs are too high for FI. Plus at 8psi you are probably going to run out of MAF pretty quick.

[Def]

Your engine will not hold together at 8 psi and an AFC with large injectors. You'll actually be running MORE timing advance than you would be at WOT and NA(more than likely) while in boost. Look up how piggybacks work, should make sense(fools the engine into thinking there is less load to get a rough inj. pulsewidth - but also means more advanced timing).

You have a lot of reading ahead of you if you really want to go "the cheap way."

[makenzie71]

What we'd do with some of our projects is retard the timing to counter the effect a little, but most often we were able to keep the injector open long enough to handle it. You don't think this is possible with the BMW?

I'm also looking into this TRM kit.

[makenzie71]

Anyone know if the TRM kit includes software?