DUDMD

The factory turbos are pretty much maxed out at 300whp each on race gas. On my low reading dyno, with ms109 and extra timing, full max boost possible it put down 602whp.
The 7675 Precision turbo is good for 1200whp as a single turbo. I think it will make 600-700whp on my dyno dynamics dyno with less than 20psi on pump gas. We can then either use race gas and add timing, or leave timing on software add more boost for my goal of 750-900whp. The main advantage is power till redline without losing boost/hp, which will turn into an even better hwy killer car.

DUDMD

Yes that will be tricky. Would be nice if I could alter the tcu I've got in there now, which has some sort of a tune since it holds M mode no problem.
I can also see if someone would maybe be able to remove the torque limiters completely, since I won't need them anymore due to not make much torque at lower rpms.
Maybe I'll have to have my boost controller drop boost to wastegate pressure for the last 500rpm to reduce power/torque.
Maybe speedriven or someone else can help out there, since they did run a 9 seconds pass on the sl600.

overZealous1

A little input for the rear mount turbo set ups. Even with all of the longer tubing, full boost is only off by about 300rpm compared to front mounted set ups. You might be able to pick up some lag starting in higher gears, but not from a dig.
You have to remember, it is sealed, doesn't take much time to pressurize the system as a whole, even when further away.
The main drawback I see, is the oiling sump, feed, and pump. Lots more parts to go wrong. But, if you have the dough, they make oil-less turbos also. Then you could turbo most cars in about a day or two.

braddman

What do you think you picked up in RWHP from just the downpipes?

DUDMD

Not sure, probably not much if any on a stock setup.
But once you start maxing out the turbos with a tune and aggressive boost, they sure do help.

I'm starting a new build thread for my new setup, the engine/trans/abc system is removed as of today. Stay tuned for new build thread for full ABC delete and single turbo conversion.

braddman

I think the DPs will help a lot on the stock setup with a tune. I just did mine (had an exhaust shop do it) and I'm waiting for the tuner to come in today so I can slap a tune on it.

DUDMD

I put down less than 10whp more after downpipes and icetank install, with factory tune.
I have my own Dyno Dynamics, no reason for me to fool myself. I did make very good power after the tune, especially maxing out the turbos and on MS109.

braddman

I'm not doubting that at all on the factory tune, but don't you think an aftermarket tune will wake that up? My BMW 335i was the same way, didn't feel much at all with downpipes until tuned.

DUDMD

Yes. That's what I was saying, on a stock tune, the gains are not huge or any at all. But once you start maxing out the turbo, any bit of extra flow gets a good hp bump.

AMG-Driver

100-Cell Downpipes in combination with only a tune will gain approx.20-30 HP at the Crank.

As DUDMD said, more effect it has when you start opening up your intake and maxing out the turbos.

alexanderfoti

Firstly, amazing work.

secondly, I am slightly confused about something.

How do you stop the ECU being unhappy about the boost levels when using an aftermarket boost controller?

If you have your boost controller set to 7psi in the midrange instead of 15psi, how does the ECU not log underboost codes? Same the otherway round, if you build more boost at low RPM than the map is dictating?

Thanks

braddman

Tune?

alexanderfoti

Sure, but in the tune is desired boost level.

Ie @3500RPM w 100% throttle and in 3rd gear I want 20Psi of boost.

If the boost controller is set to 15psi surely it will log underboost codes?

I am not aware of a way to set a desired range of boost in the tune?

DUDMD

I have the boost maps turned up high, as well as boost targets.
I haven't had a single issue with it throwing any overboost or underboost codes.
I'm still running max boost possible, except for I'm slowly ramping it up to 4K rpm, and after that it's whatever these tiny turbos could put out.

All that doesn't really matter anymore, as I fitted a single precision 7675 turbo, so now tuning is going to get weird but I don't think it will be difficult.

alexanderfoti

Aha fair enough. A (bad) mechanic told me they where very sensitive to underboost and would log codes quickly. Appears not to be the case.

Interested to see how your single turbo project turns out!

alexanderfoti

Few things.

1. most of the images have died on this thread
2. On the tune side of things, did your boost controller replace the factory one, or work with it?
Did you have to modify any torque limiters at all, or just the boost control maps to allow the higher boost pressure produced by the boost controller.

DUDMD

I have yet to see an underboost code.

DUDMD

1. Photobucket went crazy and is demanding a $400 ransom to be able to host images and show them on the forum. I will wait a week to see if they come to their senses and decides on a reasonable price or makes it free again. If they still keep the insane cost, then I will have to switch the pictures to another hosting site and relink them all.
2. I modified the main torque limiter to match my power band a little bit better. Stock boost solenoid is plugged in but has no hoses going to it at all. The boost maps are pretty much stock, except for failsafes are turned all the way up.
Otherwise eboost 2, has it's own built up boost cut feature, and boost by rpm corrections to keep my boost the same/flat till redline.

alexanderfoti

Just spotted that, that's a bit ridiculous!

Thanks for the info on the mapping side, I thought as much.

BlownV8

Any track results yet?