The flutters!

[Clifton]

Your rpms can still increase as it's making power, the boost is fluctuating from the air stalling (surge). If you could do it at WOT in a taller gear you would get to a point were the engine could use the air and the surge would stop, if it didn't kill the turbo.

 

I'm assuming it's a V or H trim is it's a T04B. If it's making that much boost at 30% TP with a V trim at that low of an rpm, it's compressor surge. The cheapest way to slow it down would be to go larger on the hotside a/r, like a .82. Going with a stage 5 wheel would work too but you would need to machine the turbine housing for it.

 

I ran a full TO4B/ V trim compressor, O trim turbine (bigger than a stg 3) .69 a/r (alot bigger than a T3 .63) and could get it to surge at low rpms, part throttle.

[HB280ZT]

Clifton,

 

The compressor side is a 60-1 hi-fi or that is what I can figure out.

James Thagard made the unit for me and he called it a hi-fi and that is put out 55 lbs/min.

 

So that being said if I change to say a H trim (49 lbs/min) will that help out?

 

Anyway i do it I need it to pull good through 6500 rpms and make about 350 -400 rwhp.

 

Thanks for the help.

[Clifton]

Looking at a 60-1 map, assuming it's using about 20 lbs at 15 psi at 3000 rpm( probably less with 30% throttle), it would put you just in the surge range.

 

I guess it depends on where you want the power and if max power is your goal. If you go smaller on the compressor side you can pick one out of the surge range and keep the fast spool. If you want max power and don't mind a little lag to get more then going bigger on the exhaust side. Changing a compressor wheel and getting a new compressor housing to match is expensive. Swapping the turbine and /or housing side is expensive too. Either can make the HP but the larger hotside would to it with less boost as it would have less back pressure.

 

Looking back at one of your posts you mention this

"When I was coming out of turn 7 ( a sever up hill right hand turn) it fluttered almost everytime I went through the turn."

That's exactly what mine would do. Part throttle/ light boost through a long turn and you have to hold the peddle there regardless. If you do alot of track days I would go bigger on the hot side. I went a little bigger and it's not even noticeable on the track as long as the revs are above 3500. On the street you could drive around it.

[HB280ZT]

Clifton,

 

I checked my TPS again today and found something that I am not sure is right.

 

First I calibrated the TPS and got the following:

 

38 closed

199 full throttle

 

Then I brought up the Throttle position on the MegaTune and it reads:

 

15 closed

78 full throttle

 

To me the last part is not right. I can see 0 closed and 100 at full throttle.

 

So what is up with that?

 

Will look into the MegaSquirt manuals some and see what is up. If you all have any ideas please let me know.

 

Thanks

[HB280ZT]

Hi All,

 

Here is an update. I have tried high spark and low spark and it still surges. That being said I do not think it has anything to do with the spark or fuel setup that I am running so what can it be.

 

I have also worked with people here in town that are using the same hotside that I am with larger compressors and not having any problems, i.e. one is running a T04E with 62-1 wheel and the other with a T04E with 57 wheel. They are also both running N/A computers, (1977 and 1975) with MAF modifications and methenol injection over 8 psi of boost. Neither one is having any surge problems. Please do not tell me that you can not run a turbo motor with an NA computer because they do and it works.

 

As for changing out the hotside I really do not want to do that as it would require me to also change the exhaust manifold and add an external wastegate, can you say lots of money and where to get a custom exhaust manifold that will not cost me my first born.

 

So I must have something wrong with the setup in my megasquirt. That being said who has a 29V or 29y4 program that works with a motor setup that way mine is?

 

Setup again;

 

MS 1 V3 with 29y4 Extra code

82 ZX turbo motor with N42 head using turbo cam, 8.2 compression ration

2mm steal head gasket

T3/TO4 turbo

intercooler

Tial BOV

running 15 psi boost

manual DIY boost controller

60mm TB

 

I really want this to run right so hopefully we can get this thing figured out.

 

Attached are several spark tables that I have tried and my last datalog and msq.

datalog200803151706.zip

megasquirt200803151551.zip

[HB280ZT]

OK people I have finally tried everything that my local Z friends and I can think of and it still flutters, BOV removed and blocked off, wastegate wired shut and vacuum removed, more and less timing and fuel.

 

So that being said I plan on removing the turbo and having it looked at by a local shop that the Z racers use and swear by to make sure it is good to go.

 

As for the intercooler is there a place I can send it to to have it checked and flow tested to see if maybe it is causing an issue??

 

But for now I have to get ready to move then it will be time to play again on my Z.

 

Thanks for your help.

 

Harry aka just call me flutters!!

[Clifton]

At a 2.0:1 pressure ratio and using 20lbs/min, a 62-1 and E57 will be under the surge line were a 60-1 is a little above it.

 

If you turn the boost down to say 10 psi will it go away? This only happens at lower rps right? Any chance you have video of it on the boost gauge. If I had my other turbo on I could go get a vid and see if it is what you are describing.

[Evan Purple240zt]

I was out with Gabe (wigenout) last night on the highway and made a WOT pull in 4th from a low RPM roll. Same thing happened that your describing. I was able to eliminate a bit of it with timing.

 

I think everyone is correct in their assessments. Just wanted to let you know that you weren't the only one.

 

Evan

[HB280ZT]

OK, Thanks for the information,

 

As for changing the boost to 10 psi or less it really does nothing as my problem is not really when I am in boost. This happens at part throttle above 3000 rpms and at or below positive boost level.

 

One question that I do have is concerning the TP information obtained in MegaTune. Who has watched it with the car on but not running to see how it functions. I did and got very interesting readings as noted in an earlier post. So can someone do the same test and let me know what they come up with?

 

Also something else that I am doing is changing my boost reference from the intake manifold and moving it to just after the turbo. I am doing it this way right now to just check if it makes a difference. If it does then I will see about tapping the turbo compressor housing for the boost reference when I have the system taken apart later this year.

 

Will keep you posted.

 

Harry aka HB280ZT

[Nigel]

Also something else that I am doing is changing my boost reference from the intake manifold and moving it to just after the turbo. I am doing it this way right now to just check if it makes a difference. If it does then I will see about tapping the turbo compressor housing for the boost reference when I have the system taken apart later this year.

 

Will keep you posted.

 

Harry aka HB280ZT

 

At the very least, this will help to minimize boost spikes (with an MBC at least). I have datalogs with the source on the manifold and on the turbo. With the source on the manifold, you can see boost pressure overshoot and then drop to the set pressure. With the source on the turbo, it hits the set pressure and stays there. This is with a Hallman MBC by the way.

 

Not sure it's going to have much effect on surge though...

 

Nigel

'73 240ZT

[HB280ZT]

Well, I was not sure if the change of boost reference would do anything to the way my car was running, however, it did! I now have to work at it to make the car flutter and this is only a temporary fix. You see I installed a fitting within 1 inch of the turbo output in the intercooler piping to use as my boost reference point until I can take my turbo apart and have the compressor housing machined for a fitting. So now I can really work on the tuning and even look at how much boost is lost between the turbo and intake manifold. May or may not be a good thing!

 

Everyone thanks for your help and I will keep you all posted on how things work out in the long run. I still have to do some dyno runs and hopefully several events at the local track, Sebring!!

 

HB280ZT

[HB280ZT]

Ok guys I finally got around to working on this flutter issue again.

 

I was in the process of putting in a smaller turbo when I decided to try one more thing before I have to rebuild part of my system to make the other turbo work.

 

What I did was to take the intercooler out of the loop by replacing it with a straight peice of pipe. And guess what no more flutter!!

 

So who can help me figure this one out now??

 

I am sorta at a loose other then at low boost/ high volume the system just can not push the air through the intercooler. And when I am really on it the pressure overcomes the restriction of the intercooler.

 

I wish I had away to read the pressure drop across the intercooler but at this time I do not so?

 

Lets see what you all come up with on this issue now.

 

Thanks

HB280ZT

[cygnusx1]

My turbo never fluttered until I switched to MSII, and got rid of the AFM and about 4 feet of corrugated plastic pipe with a cheap air filter. Once I went with a large cone air filter directly on the compressor inlet, I got surge at part throttle over 3000rpms. My thought is that the turbo moves that much more air now with the free flowing intake that I cross the surge line. I run a TO4B "Super-V" trim and a T3 turbine through a decent sized intercooler.

[Nigel]

I didn't have any problems with fluttering (chirping noise, bouncing boost gauge, bucking, running too rich) until after I installed my intercooler. I guess it has to do with the added volume of the intercooler. Part throttle boost is impossible now. It starts fluttering badly if I try to hold a steady boost level, and I either have to back right off, or put my foot into it. There's nothing in between. In fact, now it will start to flutter before I even get positive manifold pressure.

 

You can hear it clearly in the video linked below. Mine is the second car that drives by. I put my foot into it as I approached the camera, boosting to maybe 7 or 8 psi, and then backed off slightly just as I reached the camera...

 

 

Nigel

'73 240ZT

[HB280ZT]

Nigel, Mine sounds just like your car. But mine does it when I am at between 3000 and 4000 rpms and not in boost. This is a part throttle problem that goes away when I really get on it.

 

So the million dollar question is how to fix this so that I can stop messing up the turbo and start having fun??

 

HB280ZT

[HB280ZT]

Well all I have been working on my flutter problem some more and here is what I have figured out.

 

I went back to my 8 lbs actuator and was pulling 18 lbs of boost. So to put it mildly I was getting just a bit of boost creep!

 

I fixed the boost creep by having my turbo guy enlarged the internal waste gate hole to match the waste gate puck and now no more creep. This also got rid of my flutter when under low boost, 8 lbs or less.

 

Now when I install my 15 lbs actuator I get flutter again but not as bad. So my thinking is that my intercooler is causing a restriction under low boost/volume. However under high boost/volume it foces the air through the intercooler.

 

So I need to replace my intercooler and I am looking at this one:

http://www.turboneticsinc.com/products/index.php?products_id=101&category_id=9

 

Anyone use one of these? I can get it from Summit Racing for about $425.

 

HB280ZT

[Evan Purple240zt]

Nice looking intercooler.

 

Not sure if that will solve your problem, but I hope it does.

 

FYI, my car has done it with TWO different intercoolers installed of different sizes. This is not to say that we are having the same issue.

 

Evan

[HB280ZT]

Well I changed out the intercooler for a straight piece of pipe and the flutters went away, so that being said I think my intercooler was causing a restriction of some type.

 

HB280ZT

[HB280ZT]

Hi All,

 

Well have been working on the issue over that last 4 months or so and came up with something interesting. I am now opening up the waste gate just a bit to bleed off pressure and it makes the flutter go away, but still gives me full boost. So that can only mean that the turbo is the real problem. So how to fix it?

 

1 - replace the turbo - very expensive

2 - replace just the hot side - expensive and they do not have one like my current setup so I would have to replace my custom downpipe also

3 - replace just the compressor side - maybe if I can figure out which one to use?

4 - change cams to soemthing that will breath more air - maybe but what to use?

 

So what do you all think?

 

HB280ZT

[HB280ZT]

Hi All,

 

Well after lots of research and taking my turbo apart and measuring all parts it was determined that I had a modified diesel truck compressor wheel almost like an H series. Well this wheel would work great if I was running 25 to 45 psi but I was only running 15 psi. So what I had to do was replace the compressor wheel with one more suitable to my needs. I choose a 62-1 wheel and had a semi local shop change out the wheel, rebuild the turbo and do some machine work on the compressor housing.

 

After all that work I no longer have any turbo surge!! yea!! Boost time!!

 

Now I just need to work on the tune some and hopefully get to the dyno to really see what the car can do. Maybe even bump up the boost to 20 psi and see how she runs!

 

HB280ZT