Details on Transition Tuning

nocab72 · 06-27-02, 02:36 PM

As I've mod'ed my car over the past 6 months, I've noticed the boost dip during transition become more significant. With the most recent addition (FMIC) I've decided it is time to do some Boost Tuning during Transition.

Boost pre and post transition are good, even with the midpipe I am not getting boost creap with a non-ported wastegate nor significant spiking as the secondary turbo comes online.

I've got quite a few datalogit logs imported into .xls with graphs showing boost level, PC% and WG% against RPM if anyone wants to see them.

Now to my question, besides the settings in the datalogit (not that I have them all figured yet), where can I physically adjust anything on the car to aid in my transition tuning. I know I've read of at least one set screw someone was toying with that controlled pre-spool. If someone could describe in detail where I find that set screw as well as any other items I can adjust I would greatly appreciate it!

Thanks!

K

Flybye · 06-27-02, 07:59 PM

It's not a screw. It's the piece that attaches to the rod that slips over the precontrol door lever.

The rod opens and closes that little round door. Exhaust flows from behind it. The more you open the door, the more prespool you get, but the lower you primary turbo boost becomes. This is where you must compensate for it with the boost duty control. The rod pushes out to open the door. Therefore, the more you screw the end piece out, the more prespool you will get.

Make sure you put plenty of WD40 on the rod as it will have a good amount of corrosion on it being that it gets so much heat from the turbos. I got mine setup pretty much feeling like a single turbo

nocab72 · 06-30-02, 07:07 PM

Flybye - or anyone who knows

I assume that this is the pre-spool control arm which gets adjusted? Just wanted to ask before I start f*cking with things that I'm not SURE what they are!!!

BTW: Should I be able to move that arm with my fingers? it seems like it is pretty darn stiff! ie I can't move it with my fingers...

OH, I might as well ask now. Which way is MORE prespool, a longer or shorter rod lenght? And should I start by twisting it 1/2 turn, full turn, 2 turns in the appropriate direction?

Just looking for some guidance since it is going to be a pain to jack up the car remove the c-clip, adjust the rod length, unjack, test drive, etc...

Thanks in advance!!!

K

Flybye · 06-30-02, 09:15 PM

Some people will tell you this is the hard way of dong it, but I'd rather do it this way than have an extra set of hoses going into the engine bay.

Look at the turbo precontrol valve in the diagram. Exhaust flows behind it. Now look at the position of the lever in comparison with what you took a picture of. In the diagram, you see that the rod end of the flap is pointing towardds the engine, and so is in the pic you tool. Now by looking at the diagram, you can see that moving that rod piece towards the rear of the car will open the flap giving more prespool exhaust to the 2nd turbo. Therefore, the more you thread out the end piece, the more prespool you will get, and the more you thread it in, the less prespool you will get.

The rod is VERY hard to move with your fingers when it is attached to the actuator. Disconnect it from the actuator, and it will feel like a loose tooth.

It's gonna be a pain in the *** because it will probably take a few runs before dialing it in to exactly what you want. I got mine dialed in to the point where if you blink you won't see my transition, and you dont feel any abnormal power changes.

nocab72 · 07-01-02, 07:40 AM

Quote:

Originally posted by Flybye
I got mine dialed in to the point where if you blink you won't see my transition, and you dont feel any abnormal power changes.

Thanks, that is my goal as well! Will let you know how I fare!

K

laujesse2 · 07-01-02, 07:48 AM

Non-sequential it and the transition will be gone forever and no more blowing secondary turbines. With your Power FC you would have no nest either, just one solenoid.

KevinK2 · 07-01-02, 08:25 AM

if u run 12 psi+, the transition can also be tweaked by having it occur about 500 rpms earlier. people with pfc and haltech have doen it with great results. doesn't over rev 1st turbo, and keep smooth transition and big fat midrange powerband.

matty · 07-01-02, 08:43 AM

how do u tweak the powerfc?

nocab72 · 07-01-02, 09:02 AM

KevinK2 - I believe this can be done with the Datalogit & PowerFC as well. I've been playing with the Turbo Transition settings, but the furthest I've pulled the transition down is 200rpms. I'll try to pull it down even further tonight.

@ > 60% throttle (only one I'm concerned with) the Datalogit provides a Low RPM setting and a High RPM setting for the Turbo Transition. As default they are set to 3000 RPM and 4080 RPM. Last night I tried pulling both those numbers down 200RPM to 2800 and 3880 ... even with those settings the transition seemed to occur "quicker", but according to the data I logged it didn't reduce the boost dip, but did shorten the amount of time the boost was down due to the dip. ie I checked the datalogit logs and compared the amount of time when boost dropped off from say .80bar until it recovered back to .80bar. Stock settings it looked like took about a .8 of a second, with the transition #'s lower it was as quick as .4 of a second to recover.

Will keep playing!

K

07-01-02, 09:09 AM

Quote:

Originally posted by laujesse2
Non-sequential it and the transition will be gone forever and no more blowing secondary turbines. With your Power FC you would have no nest either, just one solenoid.

I will second that and not going to get in a pissing match with anyone but it is better for your turbos not haveing the transition keeps the 2nd turbo from blowing

IMO

matty · 07-01-02, 10:12 AM

rikki..we get it...you like the fact that you went non-sequential.

violator · 07-01-02, 02:58 PM

kewl now i can fix my transition problem.

DRAG0NEER · 07-02-02, 01:50 AM

nocab72...did you get your low transitional boost problem fixed?

flybye: so the rod is accessable from underneath the car? and should I remove the home depot precontrol valve after I adjust the rod? One thing to mention is that the pfc doesn't do jack in terms of boost control, how do I make it work with my home depot valves???

07-02-02, 05:52 AM

Quote:

Originally posted by matty
rikki..we get it...you like the fact that you went non-sequential.

Yeah I know but just in case he did not hear

nocab72 · 07-04-02, 07:55 PM

I haven't gotten it tuned out yet. Been playing with the turbo transition settings in the Datalogit. The datalog graphs show that the dip is getting smaller, but still not good enough.

Today I started playing with the prespool rod adjustment, threaded arm in my picture above. Problem is, after I removed the c-clip and when I spin the threaded end, the end moved, but it was because the entire rod spun. does anyone know if the end of the rod that goes into the actuator is threaded into something inside the actuator? if so, spinning the entire rod like I did probably threaded the rod further onto whatever the rod threads into inside the actuator making my total rod length shorter == less pre-spool. Anyone know if it is just spinning, or is it threading inside the actuator? if it is threaded, I'll just spin the entire rod if I can get just the threaded end to move.

answers or comments?

BTW: DRAG0NEER - my transition isn't something that is broken, I'm just trying to make it less noticable. since nothing is broken right now, I'm trying to make things better...

K

nocab72 · 07-05-02, 01:04 AM

thanks to badog vice-grips we got the end to unthread instead of twisting the entire rod...

BTW: to anyone playing with this 4 full turns out is TOO MUCH...hehehe, I don't have a boost dip at transition now because I don't build 8psi prior to transition!!! hahahah, will turn it back in 2 turns tomorrow and try it again...too hot down there right now!!!

K

Flybye · 07-05-02, 01:23 AM

You know, there ARE tiny little wrenches that can hold the actuator rod

nocab72 · 07-05-02, 01:27 AM

flybye - ya, I got the rod problem solved (it's all in the tools)...now just need to tighten it up a bit since 4 turns was about twice as many as I needed... boost graph looks like wacked now... climbs at about a 20 degree angle until 4500 @ and 5psi, then jumps to 12psi at about a 89 1/2 degree angle...

I guess that would make my boost patter look like this: 1-2-3-4-5-12

heheheh

k

Flybye · 07-05-02, 01:36 AM

Yeah, that looks about right when you open it up TOO much

Hey, I WARNED you it will take a few tries. Now you know what a big laggy single feels like.

Wade · 07-05-02, 09:50 AM

nocab72,

Why do things the hard way? You should add a small valve to your PC line in place of the pill and you can adjust the valve in 10 seconds instead of having to jack up your car. I adjusted my precontrol arm once too, about 4 years ago, because I didn't know any better.

Wade

nocab72 · 07-05-02, 10:18 AM

Wade - hahah, guess I am you 4 years ago! As the saying goes, sometimes you just have to learn the hard way!

Jacking it up hasn't been the pain, it's waiting for the darn thing to cool down enough for me to adjust the rod that is the time killer!!

I imagine that the valve is then infinitely adjustable v/s the 1 turn, 2 turn, 3 turn adjustability of the control arm itself... off to home depo I go!

K

KevinK2 · 07-05-02, 02:02 PM

Quote:

Originally posted by nocab72
I haven't gotten it tuned out yet. Been playing with the turbo transition settings in the Datalogit. The datalog graphs show that the dip is getting smaller, but still not good enough. K

This will let u know it can be done:

http://www.shaneracing.com/sr93dyno.html

not much dip!

nocab72 · 07-05-02, 02:25 PM

KevinK2 - You're telling me that SR Motorsports tuned the transition out that smooth using ONLY the PFC? No prespool valve, no rod adjustments, just the PFC?

If so, will SR Motorsports sell me that map?!?

BTW: I doubt I would run their mail-order map if they would even sell it to me, but I would certainly disect it to see what they did to smooth out the transition so well. I would pay $150 to be that much smarter, I paid a heck of a lot more than that to goto school

K

KevinK2 · 07-05-02, 05:43 PM

I doubt it's just software changes (just vague hi/lo transition settings right?) ... mabe pills and precontrol rod.