"fluttering" or whatever you want to call it, under heavy throttle-WOT

[6SENSE]

Okay, I have really hit a wall as far as performance this year and subsequently have not really had much track time since October last year. I have never experienced this before so I dont know what it could be. In another thread I mentioned the fluttering of the vdo boost gauge at higher boost levels. Im thinking that it is related to how the car is running at that higher boost and not the fault of the gauge itself. Although I did not see any crazy boost number sequence with Tlink [boost sensing] hooked up, so not sure. Car moves out fine then when about 3/4-WOT it surges or flutters (for lack of better description; not sure if Im using correct "terms"). Topend was always my strength, gaining 20-22mph on the 2nd half of runs was normal. I have finally welded up my LCAs (correctly this time) and am leaving straight now. I finally changed out my cracked stock AL drums and now along with the s10 wheel cylinders I think I can hold about 10-15psi at the line now. Plus I FINALLY ordered a line lock from Summit so I can finally do productive burnouts, sooo......... now (even though I still only have DR's) that I should be able to get my terrible 60fts down, the car is falling on its face on the topend. I think it might be boost/vac related?? (Herb and irocwithdirt also mentioned possible vac seapage in other thread, but its not from the boost gauge line as suggested) ANY ideas would be appreciated. This has been going on for a while now and is past annoying. Any route of diagnosing that you guys can suggest would be much appreciated. Last idea that I came up with recently has to do with the ATR uppipe. The thing never fit or sealed like it should. I have been using a donut/crush gasket at the uppipe to header connection to seal. This makes the pipe sit a bit higher than it should, but without it it will never seal. Because it sits higher it pushes the turbo assembly a bit higher up. This is evident by looking at the two passenger side turbo mounting nuts which are sitting high up on the bracket they tighten to. Dont know if maybe boost is escaping at higher levels? This might be a long shot, because it seemed like the turbo would still seal fine at the adaptor. Anyone ever feel this fluttering that I described before, if so what was it?

Have tried: swapping WG, coil/module, plugs changed from year(or so) old NGK-UR5s gapped @.032 to new UR5s @ .035, new boost gauge line and fittings (with loctite), have not tried new wires [yet] still have 10mm Magnecore which should be okay Then again I just swapped out my 2year old OEM/from the dealer ign module that I cant believe was faulty Quality must be going down hill, should have bought WELLS from AZ huh?

Sorry guys I know this was long. Ive got to stop ranting.....damn car

 

[6SENSE]

Also have played with fueling......over and over and over again.

 

[boostmaster]

More INFO

1) When you say fluttering are you just refering to the gage itself or is the car also experiencing some sort of effect.

2) At what level of boost do you start to feel the flutter and after turning the boost down will it go away. What is the cut off or I should say cut on point?

 

[6SENSE]

Thanks for replying.

1) Yes, not just gauge, car is experiencing it too. At first I thought of it as two seperate problems, but now it seems more likely that they are linked.

2) Over 20psi. Maybe 21-22? I can check for sure, if it stops raining. I first noticed it when I tuned in 25psi at the track a few weeks ago. Car moved out great until this problem kicked in. Blew off fpr vac hose saw kr on SM and Casper's audible sensor beeped a short beep and I got off immediately (alky saved the day again). Engine seems to be fine, compression still around 150 on all cylinders. I guess this incident may have done something to start this problem. That was the second time (of 2) that Ive been to the track this year. The first time there the car blew the vac cap off the unused port on the vac block. Didnt figure it out until the end of the night. Car wasnt running right all night.
I believe I am able to run 18-19 and it doesnt do it, need to verify again though as this has gone on for a little while now.

 

[WFO]

It sounds to me like your wastegate spring isn't strong enough to hold your wastegate shut at higher boost levels.

Are you using a heavy duty unit or a stocker?

 

[boostmaster]

DITTO!!!

 

[6SENSE]

Hmmm.............. Always comes back around to your first notion, huh .

Have tried: swapping WG..............

Okay, I dont know if they are HD or not. I have probably 4-5 of them around and probably none are HD for the fact that when I scooped them up from various places years ago who was really going fast with a hotair? (not counting that one guy in Indy ). Certainly noone around here, and certainly not the guys I got them from. Sooo.......what do I do about a HD WG? I thought that the stockers could hold these amounts (>20#), but I guess not.

 

[6SENSE]

Just thought of something. Isnt the "stocker" WG non-adjustable? Is that the stocker your reffering to, modified to be adjustable? All the ones that I have seem to be the replacement adjustable ones, not modified to be adjustable. Dont know if this matters or not, unless the replacement adjustable ones are the HD ones your reffering to.

Thanks.

P.S. also I had forgot that the WG I had on there before swapping was the one that came with my TA33 from John Craig. That wouldnt necessarily make it a HD one would it?

 

[6SENSE]

All the ones that I have seem to be the replacement adjustable ones, not modified to be adjustable.

Of course I dont know for sure though.

 

[WFO]

My GM replacement stock turbo had an adjustable wastegate on it when I bought my car...

I'm thinking all of your wastegates are regular stock type.I'm also guessing that John would send you a new regular one unless you asked for a HD one.From what I understand,because of the heavy spring in the HD wastegates you can't run low(under18-20 psi?)boost with them.

I have no idea how to tell the difference between the two...

 

[boostmaster]

I've run more than 22-24 psi on an, I think, regular adjustable wastegate. But not much more. When I got up to that level the most I had to worry about is boost creep. There is a way to test the WG with a pressure/vacumn tester to see if it is defective but I don't remember how to do it right off hand. I installed one on a friends car one time and had a serious overboost problem.

 

[6SENSE]

Testing procedure might be in my mityvac manual, I'll check. However I think you guys are right. Its unlikely that any of these are HD. Even the one from John, since I didnt ask for it. Heck I didnt even know one was coming with at all.

Where do I get a HD one from? It isnt possible to just change the spring in it right? (looks like its sealed and doesnt come apart).

Depending on the price of a new WG (guessing about $100?) this has me thinking weather or not I should be looking into a external gate, and for that matter a TH style DP that would get rid of the stock elbow (LT or Mease?) and put the money towards that. I already have a buyer in mind for my old 3" DP thats on my car now (probably wont get much for it). Sounds like alot of money though, not sure if I can swing it or not. Plus from what Ive been hearing/reading seems like the DPs arent going to be easy to get ahold of, with or without cash in hand.
What are my options here guys? What would be your recomendation with my combo? and...........if you have any idea, how much?
Thanks again for your help thus far!

 

[WFO]

I've seen guys attatch a seperate "helper" spring to troubleshoot/solve this kind of problem...basically an extra spring that helps hold your wastegate shut.

Worth a try?

 

[6SENSE]

You know now that you mention that I remember reading about someone tying the puck arm shut. For trouble shooting purposes I guess I could try that too. Just got to be careful not to let the boost shoot up to 30

I turned boost down last night and had no problems running 18~psi. Car was quick but just not as fast. It likes to move more air. Maybe my money would be better spent just sending the turbo to John Craig and have him turn it into something bigger like a 60? Then I wouldnt have to run as much boost to gain the same performance.

 

[irockwithdirt]

U runnin that much boost on that old engine U put in last year??

 

[6SENSE]

Originally posted by irockwithdirt
U runnin that much boost on that old engine U put in last year??

Hey, it checked out good to me I cant help it, Im a boost addict Hows your car comin along Kevin?

I tied the puck arm tight this morning with some utility wire. Driving [carefully] I was able to verify that the WG has got to be the problem. Boost gauge held steady with no problem well in to the 20's. Uhh, how about 27psi Oops didnt mean to get it that high, but all was okay. I had already had the alky turned up a bit just in case (progressive does its job, 0 kr). I think it would be alot different if that was 27psi at WOT though, with rpms up valves opening all the way, etc. Load would be a bit more on the engine I would think.
So, I guess I should call John Craig about a HD WG?

By the way, I spoke to someone today with a '87. He said he could identify his HDWG (from John) by the rod being larger.

Thanks for all the help guys! Hopefully I can get the right WG soon, get my line lock on and then finally get some improved track times.

 

[6SENSE]

Just got off the phone with Limit Engineering. They said they have no HD WG for the 84/85. They only have the single vac port type for the 86/87. The guy I spoke to said that my best bet would be to use a pressure regulator attached to (I guess teed in?) to the top port of the actuator (furthest from rod ). I remember always hearing about using a fish tank bleeder valve but thought it was just for boost control. Didnt know it was to actually make more boost available. Why havent I heard more hotair guys in this section talk about this? I know Im not the only one that has suddenly ran into this "boost wall".
I recall about year ago a guy at the track with a Chrysler Omega, does that sound right? (I think thats what it was, not positive). Little thing looked like it would be in the class with a VW Rabbit, but a turbo 4cyl. He was running low 15s I think. Next time I saw him he was showing me where he added a fish tank pressure regulator. I didnt think much of it. Next thing ya know hes running lmid to ow 13s!

Anyway, anyone have any more info on this pressure reg thing, let me know. Or if you just went to a single port WG, whats involved. Thanks.

 

[irockwithdirt]

I'm no expert on this, but my car has a single port (that means one vac line, right?)WG on it........was that way when I got it.

If I can find some 120 grit aluminum oxide blasting media my car should finally be running this weekend. Any idea where I can get some in the St Louis area?

 

[boostmaster]

A few years back I bought a adjustable wastegate for my 84 from postons, came with one vacumn port I forgot how to route the vacumn lines but I think some people are doing the dual vacumn line regulators the same way.

 

[6SENSE]

Okay heres the routing for the single port WG:http://www.engraver1.com/help/intake2.gif It was in the hotair sticky, duh
We cant just use the WG designed for 86/87 though can we? Arent they alot shorter than ours? At least thats what I recall, without actually measuring or putting them side by side. Or should I just forget about it and do the fish tank regulator thing?

Kevin, not sure on that blasting media. I would start looking in the yellow pages or keep asking around. I asked my brother who works in a body shop and he didnt know off hand. Not sure if he can find out, they work with mostly new cars. I know there has to be a place in the area though. I used similar stuff when I worked in a local auto machine shop a few years back for cleaning aluminum heads etc (glass bead).