Creep or something else?

[turbojimmy]

So my car ran pretty slow last night at the track. I only got 3 runs in and each time I forgot to look at the boost gauge. I know it's hard to believe, but I get so fixated with the knock gauge I forget to look at other things.

Anyhow, it ran a 12.578 @ 111.54. Forget the 12.xxx, it's because I spun for a good 100 feet. The MPH is off a bit. I got up early this morning to goof around a bit and see where my boost was.

From a dead stop, boost rockets up to 17-18 PSI. That's what's causing the slow MPH. If I stay in it, it creeps up almost to 20. However, and this is the interesting part, if I'm cruising along the highway at like 50 MPH and nail it, it will drop a gear and boost will shoot up to 22-23 PSI. The 22-23 PSI is where I need to be (more actually) but I don't think it's happening until the end of the run if at all. If I adjust the wastegate so I get the high boost from a dead stop, it gets too high on the highway.

I know the wastegate needs ported. Would this cure this behavior? It's a PT-61 hooked up 'tuner style' with a bleeder.

TIA,
Jim

 

[turbojimmy]

I forgot to mention that I have a 3500-3600 stall 9x11 converter so it should be spooling immediately.

Thanks,
Jim

 

[turbojimmy]

I took the turbo off and it looks like someone else has ported the housing (I bought the turbo used). Here's a pic: http://www.turbojimmy.com/PT61_port.jpg

Should I even bother porting this some more? Would it make any difference? I'm thinking my problem isn't actually creep.

TIA,
Jim

 

[turbojimmy]

So I figured I'd continue this conversation I'm having with myself......

Even though it didn't look like I had much to go, I ported that exhaust housing anyway. Turns out that once I was done there was a pretty big difference.

The creep is pretty much gone. The boost still increases slightly at highway speeds WOT, but it's much better. I was picking up 6 or 7 PSI versus off-the-line boost. Now it's about 2 PSI.

Is it time for an external wastegate?

Jim

 

[fontana]

Sorry that I can't help with your problem, but I should at least let you know that you are my favorite poster on this board. I've learned more from you with how you try to understand how things work, and then apply that knowledge to fix a problem. Keep up the good work!

Wayne

 

[turbojimmy]

Sorry that I can't help with your problem, but I should at least let you know that you are my favorite poster on this board. I've learned more from you with how you try to understand how things work, and then apply that knowledge to fix a problem. Keep up the good work!

Wayne

Thanks! I don't post as much as I used to, but there are far better and more knowledgeable folks on the board. I do appreciate the complement though and I'm glad you enjoy my trial-and-error method of figuring things out

Jim