• Got the Contributing Memberships stuff finally worked out and made up a thread as a sort of "How-To" to help people figure out how to participate. So if you need help figuring it out, here's the thread you need to take a look at -> http://www.corvetteflorida.com/forums/showthread.php?t=3581 Thank you, everyone! Rich Z.

427 engine (part 2) - RHS block

craig04c5 said:
Which Tigershark manufacturer did you go with Rich, Starcraft? Will you post on the install?
Click to expand...

Starcraft said that the bumper fascia I got was "original" so I presume it is one of theirs. This hasn't been much on the front burner, as I've been puttering around with the tuning stuff lately. And then I played around with trying my hand at wet sanding too.

I won't be doing the painting and install of the bumper myself, so best I will be able to do is to take pics after the install. And hope that the color matching is OK. I didn't screw up the rest of the paint job on the car too much with my wet sanding experiment, so I can live with the results for a while.

I've been scraping the paint off of the inside of the Tiger Shark bumper fascia here and there, as it pretty much just fell off with light scraping. The paint job on the front seems pretty decent, so I'm guessing there will be minimal fitting and prepping of the fascia itself beyond just removing the black paint that is currently on it.

And I'll be perfectly honest that after what I went through with Chris Harwood and Aaron Scott, I'm really not all that excited about putting my car into someone else's hands for a while. Nor believe a word they tell me about their expertise level. So that certainly is an influence on my dragging my feet about getting this done.
 
Rats....

Connie and I got up early this morning with the intention of driving up to Thomasville, GA with the Cruisin' Corvettes group. But when I started up the car it started fine, but after a few moments it stalled. Further startups got the same response, especially if I were to blip the gas pedal. The engine would rev up OK, but when the rpms dropped, they would drop way too far. Not sure what happened, as I took the car out for a drive yesterday and it didn't have this problem then, nor before. I loaded back in the previous tune, and it still did the same thing. After it warmed up a bit more, it seemed to run fine, but by then it was too late to head on out to meet with the group going up to Thomasville.

Oh well, I guess my car just plain flat out REFUSED to go back up to Thomasville, GA. All things considered concerning what it went through, I guess I can't blame it too much. :shrug01: I guess I had better not ever let it know I'm intending to take it to Blountstown, neither.

But I suppose I need to figure out what happened and fix whatever the heck it is. Hopefully it's just a tuning glitch that I caused myself and not something mechanical or electronic failing in the car. I did some logging while the problem was still going on, but nothing really jumped out at me in the log file as to the cause. So I'm letting the engine cool all the way down and will start it up again later today with the scanner program running. That's the problem with trying to diagnose cold start issues. You really can't get more than a couple cold starts each day to even look for the cause. It seems to take a long time for the engine coolant temps to drop down to ambient room temperature.
 
As a followup to the previous post, apparently it is a tuning issue. I've pretty much got it fixed, but I'm documenting that sort of stuff elsewhere -> http://www.corvetteflorida.com/forums/showthread.php?t=90592

Meanwhile, today I figured I had been spending so much time playing around with the tuning, that maybe I need to just check all the mechanical stuff I've done over the past year and a half or so to make sure everything is still holding together and not coming loose on me. So I put her up on the lift and checked all the nuts and bolts, connectors, wire ties, etc., etc. Everything looked in great shape. Nothing coming loose. Nothing leaking. Well there was about a half a drop of oil on one of the oil pan bolts at the back of the driver's side of the engine, but nothing on the floor, so not too bad. Nothing looks burned, cracked, or broken. Surprisingly those brake pads I put on produce very little dust. And the zinc finish on the rotors is holding up right well.

Looks like the rains are going away for a while, so I hope to get the car back on the road and do some throttle response improvements with the tuning.
 
Rich, did you use ceramic pads on the brakes? What brand did you use?
I'm looking to replace the pads on my car and I'm looking for something
that works well and has a LOT LESS dust than my current pads. Did you do
all 4 wheels or just the front? I figure that if your brakes can stop the C5Z,
they will be MORE than adequate for my car! :D
Andy :wavey:
 
navy2kcoupe said:
Rich, did you use ceramic pads on the brakes? What brand did you use?
I'm looking to replace the pads on my car and I'm looking for something
that works well and has a LOT LESS dust than my current pads. Did you do
all 4 wheels or just the front? I figure that if your brakes can stop the C5Z,
they will be MORE than adequate for my car! :D
Andy :wavey:
Click to expand...

Andy, here's what I am using -> http://www.corvetteflorida.com/forums/showthread.php?t=72776

I replaced all four wheels at the same time. Figured I was replacing all four hubs, putting on braided stainless brake lines, and the rotors were rusty anyway.
 
Well, since this is related to a mechanical issue, I figure I need to post this here.

I've got a hiccup in the boost from the turbos, and not sure where it is coming from. It happened earlier and I found that the airbridge coupler had come loose because the 4 to 3.5 inch coupler I had between the throttle body and the top of the airbridge was too flimsy and apparently ballooning out under boost. This eventually pulled the bottom of the airbridge off of the MAF sensor housing.

I bought a new, thicker coupler, and put it all back together, thinking that problem would be solved. But when I took the car out again (between rain showers) I found that I had the same hiccup under boost right around 7 psi. When I got back home, I inspected all the couplers, and everything looked just fine.

Now one thing I did do right before the first hiccup was to block off the air vents on the wastegates, as I had noticed that boost would not climb over 8 to 8.5 psi, even with the 10 lb springs in the wastegates. So I thought that by closing off the air vents, it might allow boost to get a little higher. So MAYBE my closing off those vents caused this problem.

Anyway, I decided to contact Tial about the correct way to use those air vents and I explained how those wastgates were plumbed with the vacuum lines. The guy from Tial responded that those endcap air fittings SHOULD be open and exposed to ambient air. But on top of that, come to find out that the operating fittings to control the wastegates themselves are hooked up incorrectly. Not sure who did the plumbing on them, but whoever it is ran the vacuum line up to the back of the intake manifold. Come to find out that this is NOT correct. The wastegates aren't designed to be exposed to both vacuum and boost, and SHOULD have the lines referenced somewhere between the compressor housing of the turbo(s) and the outside of the throttle body plate so that they don't put vacuum to the wastegates.

They SHOULD be hooked up something like this:
wastegate_hookup2.png


Disregard the boost controller for now. It's the line itself between wastegate and turbo housing that is relevant. With the dual turbos, I would simply have to use a "Y" joint to run to both of my wastegates.

So yeah, something else mechanically that is still screwed up.

Right now I'm trying to figure out the best way to fix this problem. And I need to figure out whether the hiccup was caused by my closing off those air vents or not.

Wonderful.....
 
shakedown067 said:
Hopefully it's a quick plumping fix. You working on it this week/weekend?
Click to expand...

Still thinking on the best way to go about this. Apparently some people believe that hooking the wastegates up to the intake manifold is OK, regardless of the fact that it was Tial (the manufacturer of the wastegates) that say they were not designed that way.

Seriously, does anyone really KNOW what they are talking about with any of this stuff? With a lot of the stuff I have learned lately, it appears that maybe one person TRIED something by the seat of his pants and it SEEMED to work, wrote something on the internet about it, and then that became the source gospel that everyone else is following.

I guess I've just got to gather as much info as I can and then run it through a BS filter of my own to figure out what just makes SENSE to me. Part of the equation for that BS filter has to include the qualifier of "inconsequential differences" too, since maybe some things don't make any significant difference to the desired outcome. Maybe the difference between "perfect" and "it works OK" doesn't really matter in practical application.

So, we'll see.
 
It works "ok" seems to be the common trend these days. Why do it right, when you can just get it done? If they did it right the first time, then why would you come back to get something fixed...wait, what?
 
Heck in a lot of instances I found while fixing my car, I would have been perfectly happy with an "OK" solution instead of the many instances I found of what appeared to be "I hope Rich doesn't notice the crap I did to his car." :rolleyes:

I just got off of the phone with Turbosmart, as they sell a manual boost controller that looked like it might operate as a check valve. That would have been great, because I wouldn't have had to do anything but splice that controller into the vacuum/boost line going to the wastegates. But they also say that wastegates really should not be exposed to both vacuum and boost. Just boost only.

Guess I'm going to have to be thinking about drilling and tapping a hole into one of my compressor housings to mount an air fitting there. Too bad mine didn't come with one already installed, as I've noticed quite a few turbos already come with a fitting there. Not mine, though.
 
only turbo's that are internally wastegated have that tapped hole and fitting installed. you should notice that there normally is a flat spot cast in the housing where the material is purposely thicker to allow for this provision.
 
Well, I'm just going to redo the wastegate stuff completely. I know the wastegates are SUPPOSED to be 10 lb springs because they are yellow, but they are supposed to both be new and one of them just seems to have shed it's paint quicker than the other.. Not only that, but the yellow paint is not the same shade on both of those springs.

wastegates_20.jpg


Since they were both supposedly installed at the same time, this just strikes me as odd. So I ordered two complete new wastegates and am going with 14 lb springs in them.

Then I'm going to order fittings and hose to run a separate line from each turbo to it's respective wastegate directly. Of course, I have to drill and tap holes into each turbo compressor housing for this, but it is what it is.

Meanwhile, I am trying to find out if the turbos on the car are actually of suitable size for my 427 engine. What I was told by Turbos Direct (the place where Aaron Scott send my turbos to have them rebuilt and upgraded), is the following when I asked them directly about the turbos:
Looks like they are T3/T4. 57 trim on the comp side, and stage 3 on the turbine side. Each one is good for about 425-450hp at the crank.
Click to expand...

Looking at pics I took of the turbo housings myself, I see the following info stamped on the housings:

  • Turbine (exhaust) housing - A/R .48
  • Compressor housing - A/R .60

turbo_size_01.jpg


turbo_size_02.jpg


turbo_size_03.jpg


turbo_size_04.jpg


turbo_size_05.jpg


Quite honestly, the above really doesn't mean anything to me. Yet. Just something else I guess I need to learn to figure out if what I was told about them is anywhere close to the truth or not.
 
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Got to take the car out today, as I wanted to do some more data logging, and I had opened those vents back up on the wastegates, so I wanted to see if that would possibly fix the hiccup I've been getting. Car ran like a champ, and I did NOT get that hiccup during boost, so hopefully that goofy little change was what was causing it.

But boost still max'ed out at just over 7 psi, so something still isn't right there. Boost topped out at 150 kPa and fell about 7 kPa while I was holding it at WOT for 3 seconds. Three seconds doesn't sound like much, but believe me, I was moving pretty good by then. So that was quite enough.

Oh, one other thing I found while looking through the tune. All of the tables to enable misfires were disabled. Not too keen on thinking that misfires wouldn't be reported to me, so I fixed that problem too...
 
Someone over on the EFILive forum made a post that sort of filled in the blanks for me concerning WHY the wastegates should be referenced to the outside of the throttle body plate.

ACCLR8N said:
I referenced my wastegate right before the throttle body. After the TB, when you let off, the 'gates will close and spike the pressure in the charge pipes. It might sound cooler coming out of your BOV but isn't doing anything else any good.
Click to expand...

I've been trying to think of why hooking the wastegates up to the intake manifold could be bad for anything, and that provided the key to my understanding. The blow off valve is activated when there is a pressure differential between the the outside of the throttle body plate and the inside of that plate. However, with the wastegates referenced from the intake manifold, which is on the INSIDE of the throttle body plate, of course, when the throttle body plate closes suddenly, such as between shifts, the wastegates will have a sharp transition between boost and vacuum that will slam the wastegate valves shut abruptly, and likely forcefully. When the wastegates are referenced to the outside of the throttle body plate, the control is merely between high boost and no boost, as the blow off valve relieves pressure, which should be a much milder transition, and less wear and tear on the wastegate valve and diaphragm.

I'm thinking that abrupt and forceful transition between full boost and full vacuum might be what Tial is talking about in relation to possibly damaging the wastegate.

I feel better now about my decision to change the wastegate plumbing. I wasn't really sure it was necessary as I couldn't come up with a scenario that seemed like it could hurt anything. Guess I just didn't think it through long enough, but the reasoning seems much clearer to me now.

So this is a FYI if anyone else might be pondering this problem. (Probably not, but what the heck anyway.)
 
Rich, would the abrupt change (throttle plate open to closed like during a shift)
be a likely cause of the separation of the plumbing at the air bridge/coupler/
throttle body area that you've been seeing? That area might be ok for low
delta changes, but when smacked all of a sudden, it lets go.......
Just wondering (in print, NOT out loud! LOL)
Andy :wavey:
Sounds like you're creeping up on it slowly but surely, which is DEFINITELY
the preferred way to go! :thumbsup:
 
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