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View Full Version : SBEC VNT, 89' 90', 2.2 liter, 8 valve, Attempt to reduce VNT overboost



quantum
04-06-2008, 01:09 PM
Attached is a copy of a cal I've been working on to help stop the stock overboost of the VNT. It isn't perfect, but it is working pretty well. On a 48 degree day I can hold wot in 1st and 2nd without overboosting. 3rd still overboosts at wot unless you let up a bit, but it gives you time to react. This cal spools up to 10psi just about as fast as a stock VNT cal, then it climbs to ~15psi slowly. It's a work in progress, but I thought I would put it up so anyone else with a VNT that wants to give it a try can. This cal also includes a 3600 rpm stage limiter and Shellgames CE flash on knock and is set for the stock injectors and 2bar map. Let me know if you have any issues or suggestions.

Quantum

EDIT:

I put this code as an option in my Phosphate SBEC code. Download that and build as per it's instructions if you want this boost control.

quantum
04-22-2008, 08:03 AM
I'll be posting up a new version this weekend I hope. I've added a few more data points to help control the boost and now have it stable at ~14psi at wot in 3rd and higher; I'm just hammering out the spool up time to keep it as fast as possible with out spiking. If anyone has had a chance to use the version up now and has something they want to see changed or added please let me know. Thanks.

quantum
04-24-2008, 10:16 PM
For those who tried this; do you like the slower spool from 10 to ~15 or would you prefer it to hit the max as fast as possible? Also, what have you been seeing as your max in 1st and 2nd (every car is a bit different) and what would you like as max boost? Thanks.

quantum
04-26-2008, 02:21 PM
Ok; I didn't get any feedback (not that it's supprising; really how many socketed stock VNT cars are out there) so I'm posting up what I have.

It works pretty well IMHO. I spent an hour driving with it today and I didn't hit ooverboost cut out at all, though I found that in the upper rpm's (around 4500 and higher) I still see 17psi in 3rd (My car has a high flow exhaust, so people with stock exhaust setups my not have it creep up like I do). The nice part is I don't get any part throttle overboost and if you keep a eye on what your doing you can keep it under 15 psi at a"WOT" & high rpm.

The spool up is the same as stock till ~11-12 psi and then it slows down as it heads to 15 (it doesn't take long, but you can tell the difference).

If anyone has an issue or wants changes (boost revisions, 3-bar, change the spool up, etc) please relpy and I'll see what I can do. The file contains the .bin, .tbl and .calx files. Enjoy.

Whorse
06-13-2008, 12:40 AM
I might be willing to help. I have a pretty stock VNT and I want to try a socketed cal just to make sure the computer works with the socket. Once it's done I'd like to get a cal modified for about 14psi with FFV injectors.

quantum
06-13-2008, 01:35 PM
I'm sure I can help. Limiting the VNT to 14 psi with out overboost shutdown is probably going to be harder than scaling for the FFV injectors (so long as you know their flow rate).

Whorse
06-14-2008, 02:58 AM
I'm pretty sure they are just under +20s. I think I will manually work on controlling the VNT. I have a few tricks I want to try, and I am fully aware that it's impossible to control it precisely without a wastegate.

I am going to try and get a couple issues sorted out, socket a SBEC this week and then we'll keep in touch and try to get a nice cal tuned in!

boost geek
06-14-2008, 03:36 AM
Jason does beautiful work socketing boards.:thumb:

Whorse
06-14-2008, 11:53 AM
Heh thanks for the free plug dick. I might head out to a local elx store and see if I can find some zif sockets to get these boards done. Really hoping to get some extra help on this.

Whorse
06-26-2008, 04:18 AM
I've been running this for a week now. Stock exhaust, stock boost. Runs just like stock, except with the stage limiter which is nice. First day I thought I had a little bit of spike but that was probably just when I blew off a vacuum line to a solenoid. Since then it's been just like stock. Exhaust should still be on the way so I'll report back when that is installed.

What tables were changed by how much to affect the overboost?

quantum
06-26-2008, 08:00 AM
I've been running this for a week now. Stock exhaust, stock boost. Runs just like stock, except with the stage limiter which is nice. First day I thought I had a little bit of spike but that was probably just when I blew off a vacuum line to a solenoid. Since then it's been just like stock. Exhaust should still be on the way so I'll report back when that is installed.

What tables were changed by how much to affect the overboost?

I added extra data points to the WG duity cycle V.S. boost table and made adjustments to that curve so it doesn't spike so damn hard and to help bleed off high boost better. The how much part is a bit hard to describe; I left the spool up stock, but ramped down the duity cycle after boost goal by a lot.

My over all goal was to leave the car feeling stock and avoiding the over boost VNT cars are prone to get, as well as add the stage limiter and CE flash on knock.

Devsdaytona
07-23-2008, 11:43 PM
Alright, I tried this out in my car, seemed to spool up nice and smooth and everything, went to about 13pounds maximum the whole time, was a pretty cool day too.

I have no experience testing cals, so don't quote me. But I like it.

Under WOT and occasionaly under part throttle it would flash the engine light, I'm assuming its the knock ce flash which worries me.:confused2:

Car is a bone stock 90 Daytona Shelby

This is the first time I have tried a cal with a staging limiter and it was pretty sweet, but apparently I need some solid motor mounts

Thank You:thumb:

Badger
07-24-2008, 12:51 AM
love to try this on my new VNT.....but need time to do all the PM first. Glad to see people working on VNT stuff. THANK YOU!!

quantum
07-24-2008, 08:18 AM
Alright, I tried this out in my car, seemed to spool up nice and smooth and everything, went to about 13pounds maximum the whole time, was a pretty cool day too.

I have no experience testing cals, so don't quote me. But I like it.

Under WOT and occasionaly under part throttle it would flash the engine light, I'm assuming its the knock ce flash which worries me.:confused2:

Car is a bone stock 90 Daytona Shelby

This is the first time I have tried a cal with a staging limiter and it was pretty sweet, but apparently I need some solid motor mounts

Thank You:thumb:

I'm glad you like it. I got a little "knock" as well on my car, but I think the stock knock sensor curve was made a bit over sensitive. If you want to get rid of it; keep an eye on around what RPM you see it and then you can increase the voltage at that RPM in the KnockFromRPM table a little till it goes away. If you don't feel comfortable with that; send me the info and I can make a few adjustments and email you the adjusted file (though it may take a few tries to get it perfect).

Devsdaytona
07-24-2008, 12:54 PM
I heard that other engine knocks, clicking etc can cause it to go off which is very possible with this engine. i'm gunna try driving it some more and maybe adjust that the knock curve thing.

Thank you

Devsdaytona
07-25-2008, 02:42 AM
Had a good run in the car today, the ce didn't flash under WOT, the sensor is definatly being tripped a piston pin knock that the engine has at part throttle under light load.

Just though ya should know that it wasn't a cal problem.

thank you

Whorse
07-26-2008, 01:54 PM
Think you could be a gent and post a cal of this with +20s and stock 2 bar map? I've run this in my car for a while and it's terrific. I'm going to be putting a 2.5" catback on the car so I'm curious how it will compare before and after.

quantum
07-27-2008, 08:56 PM
Think you could be a gent and post a cal of this with +20s and stock 2 bar map? I've run this in my car for a while and it's terrific. I'm going to be putting a 2.5" catback on the car so I'm curious how it will compare before and after.

Here you go. Give this a try.

Badger
08-04-2008, 08:51 PM
whats the latest on this CAL? Interested in hearing more about it!

quantum
08-05-2008, 08:58 AM
whats the latest on this CAL? Interested in hearing more about it!

Nothing recent except for the +20 adjusted cal I did for Whorse.

It runs just like stock; except it tapers off at ~13 psi (like the stock cal should have) instead of over boosting. It also has a rev limiter of ~3500 when under 5 mph and CE flash on knock. If you have any questions please feel free to ask.

butchsuppe
08-06-2008, 01:02 AM
I'm running a VNT on a SMEC car using a grainger per DDG artical # 49 in the turbo data base. This is my spare turbo while my T2 turbo is being rebuilt. On a stock motor this turbo was controled to 15 PSI, but now on my modded motor I cannot control the boost. WHAT exactly is the computer doing to control it and has anyone figured out how to do it mechanically. I came to the concusion that the spring in the actuator is to strong to respond to the boost signal. ( may be wrong about that ) The VNT is SOOO much more fun than the T2.:thumb:

quantum
08-06-2008, 10:28 AM
I'm running a VNT on a SMEC car using a grainger per DDG artical # 49 in the turbo data base. This is my spare turbo while my T2 turbo is being rebuilt. On a stock motor this turbo was controled to 15 PSI, but now on my modded motor I cannot control the boost. WHAT exactly is the computer doing to control it and has anyone figured out how to do it mechanically. I came to the concusion that the spring in the actuator is to strong to respond to the boost signal. ( may be wrong about that ) The VNT is SOOO much more fun than the T2.:thumb:

I believe that when in vac the computer is sending vac to the top port and atmosphere to the bottom. As the car transitions to boost it switches to atmosphere at the top and boost at the bottom. As it reaches boost goal it is suppose to send boost to the top port and atmosphere to the bottom to slow and maintain boost.

Badger
08-07-2008, 12:11 AM
quantum,
the cal you created for the VNT. Does it make the same HP as the stock cal? Also will it work ok on an otherwise stock '89 CSX VNT?

Either way, thanks for the work you have done on this because it benefits others with VNT motors.

butchsuppe
08-07-2008, 01:33 AM
Today I took the grainger out and run the hose unrestricted to the top nipple, the lower nipple has been plumbed with 2 vac hoses with 2 check valve that vent under boost. Still nails my 15 PSI boost gauge. Next thing I thought about trying is unvented check valve so the vines don't fully close. All I really want to do is to lower to boost to maybe 7-12 PSI as my modded 2.5 has enought power to please me at the moment.

quantum
08-07-2008, 06:54 AM
quantum,
the cal you created for the VNT. Does it make the same HP as the stock cal? Also will it work ok on an otherwise stock '89 CSX VNT?

Either way, thanks for the work you have done on this because it benefits others with VNT motors.

I ran it on my CSX. HP should be the same at the same boost levels. If you normaly run your CSX at wot and close to overboost shutdown it will seem a bit slower. :thumb:

Badger
08-08-2008, 02:43 AM
I don't so I guess I wouldnt notice. Whats the difference between it and the FWD stage 2 VNT cal......any idea?

quantum
08-08-2008, 07:43 AM
I don't so I guess I wouldnt notice. Whats the difference between it and the FWD stage 2 VNT cal......any idea?

This is pretty much stock. Stock boost, stock timing, 2-bar map, stock injectors (though all of these can be modified). The only non stock part of the code is the boost control at boost goal, CE flash on knock, and staging mod (rev limiter). The cal can be changed for more performance, etc; but as it is posted I just ment it to allow VNT cars to run with no overboost.

Badger
08-15-2008, 01:47 AM
Quantum,
what would a 2 1/2 mandrel bent full exhaust system do to your cal? Would your cal be able to control the possible overboost issues with the opened up exhaust?

thanks.....

quantum
08-15-2008, 10:50 AM
Quantum,
what would a 2 1/2 mandrel bent full exhaust system do to your cal? Would your cal be able to control the possible overboost issues with the opened up exhaust?

thanks.....

My CSX had a 2.5" exhaust. The cal kept me to ~15 psi in 1st-2nd. I could still overboost in 4th-5th, but I had to say wot for a while and not watch my boost to get there, it does a nice slow climb from 13psi.

I'll help you tune it in as much as I can, but with an open exhaust and cool temps overboost is hard to avoid.

quantum
08-21-2008, 08:59 AM
I'm working on a hot restart issue with the cal that occurs only when the injectors are scaled larger than +20. As soon as I have it nailed down I will post a new version.

Under pressure
12-27-2011, 04:29 PM
anyone here have any additional data ?

4banging
08-20-2013, 07:21 PM
who what and how do i get this cal im my 89 csx??

cordes
08-20-2013, 07:43 PM
who what and how do i get this cal im my 89 csx??

He hasn't been on the boards in a couple of years. Does www.boostbutton.com offer anything for the VNT cars? That's probably the way to go these days.

4banging
08-20-2013, 09:09 PM
i sent them a message too

Badger
08-20-2013, 09:21 PM
Rob (boostbutton.com) can help you. His customer service is excellent as well!

4banging
08-20-2013, 09:47 PM
he has already replied so i second that