Interesting boost issues...

[uberswede]

As mentioned before, I purchased my Talon with a bunch of bolt-ons already on it. Everything (i think) is listed in my profile.

I finally got the boost gauge working properly (last guy wired up a bit of an abortion under the dash, and I had a hell of a time determining all the problems)

Anyways, my issues here are as follows...


#1.) My boost seems to be different with every gear. 1st is always around 7 or 8 psi. 2nd gear is around 13-14 psi, and 3rd is around 16 psi. I haven't tested above 3rd gear yet...

There's some kind of MSD adjustable ignition system under the intake... could that have anything to do with it? It's a pretty massive and unknown turbo, and there's also a GReddy boost controller... which brings me to my next problem.



#2.) The boost controller seems to do absolutely nothing. I've read around that the hoses may be hooked up backwards. I'll check this out tomorrow and see... but does anybody else have any ideas? No matter where I put the boost setting (from 0 to 1.0 to 2.0), the boost levels on the gears are all still about the same as listed in #1.

I've also noticed that the gasket between the turbo manifold and the turbo itself looks like it may be blowing out, or is already... sounds like there's an exhaust leak too... could this be contributing to my issue?

 

[jrohner]

#1.) My boost seems to be different with every gear. 1st is always around 7 or 8 psi. 2nd gear is around 13-14 psi, and 3rd is around 16 psi. I haven't tested above 3rd gear yet...

I've also noticed that the gasket between the turbo manifold and the turbo itself looks like it may be blowing out, or is already... sounds like there's an exhaust leak too... could this be contributing to my issue?

Load is higher in higher gears, so it's not uncommon to for the boost to be a little different in each gear.

An exhaust leak before the turbo messes up your boost (mostly makes the spoolup really slow). This definitely could contribute to your boost issue.

I have good luck with copper RTV with no gaskets anywhere (in the exhaust) except between the head and manifold.

 

[BLINKY619]

sounds to me like turbo lag not to mention that you said it had a massive turbo.... is this driving it normally or at wot? also a exhaust leak in the manifold before the turbo can really make your turbo slow and laggy

 

[uberswede]

Well, I suppose a LITTLE different makes sense... but should 2nd gear be pretty much double the PSI than in 1st gear?

I definitely need to get that exhaust leak found and rectified ASAP. That could definitely solve SOMETHING, I hope.

And I'm not sure what you mean by "copper RTV with no gaskets anywhere". I mean the "no gaskets anywhere" part is pretty clear. Do you mean you don't even use a gasket between the turbo and manifold?? What's copper RTV?



And yeah, it's a huge turbo. I only found a serial number on it. I need to grab that and look it up when I get a chance. There's definitely considerable lag for sure. There's almost no power until around 5000 rpm .

 

[BLINKY619]

5000rpm WTF dam your big time lagging you should do a boost leak test. make sure you have no boost leaks and fix the exhaust leak

 

[uberswede]

I don't feel much of anything until after 5grand... after that it starts flyin'... well kinda. It's pretty decent. But isn't it normal for a turbo that big to lag that much?

 

[BLINKY619]

i don't feel much of anything until after 5grand... After that it starts flyin'... Well kinda. It's pretty decent. But isn't it normal for a turbo that big to lag that much?

well first of all you have to figure out what turbo you have and that will let us know alot more...!

 

[uberswede]

Took a quick look at the turbo, it says J84A on it. Just doing some quick research, it looks like it might be an eBay Garrett t70 knockoff of some sort.

Given the other ebay parts already on the car, this wouldn't surprise me. Looks basically like this one

MonstA T3/T70 800HP 9SEC CAR TURBO NISSAN SKYLINE VL on eBay.ca (item 370356648567 end time 01-Apr-10 05:30:24 EDT)

Here's a quick phone shot of the turbo

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As for the exhaust leak... yeah... i put my hand down near the manifold/turbo gasket, and it's definitely blown out. That could certainly be causing more lag than wanted, the disgusting sound in the front, as well as possibly my issues with my boost controller, which is a GReddy PRofec A

This guy here http://image.modified.com/f/2835520...st_controller_comparision+greddy_profec_a.jpg


When I went out just now, I tried all settings on the boost controller... 1st gear was about the same no matter where I was. 2nd gear at the lowest boost setting gave me about 12psi, and at the highest setting about 15psi...

I'm thinking this exhaust gasket could most definitely solve my boost/lag issues... but maybe not all of them?

Also, any suggestions on gaskets, or will just any do, really?

 

[Marty Staggs]

Always test for boost in 3rd gear or higher.
1st gear will never put enough load on the motor to make full boost.
Yes every possibloe exhaust leak will have a negative effect on boost and spool-up.
Your turbo is probably too big and will never make you happy.

 

[TurboTerror99]

Quote: Uberswede
"And I'm not sure what you mean by "copper RTV with no gaskets anywhere". I mean the "no gaskets anywhere" part is pretty clear. Do you mean you don't even use a gasket between the turbo and manifold?? What's copper RTV?"


RTV= Room Temperature Vulcanizing compound. It's just a term for gasket maker. Copper refers to the grade/purpose of that particular RTV. I.E. ultra black, ultra grey, clear, copper. They're used for different purposes and Permatex makes them. I believe copper is "high temp."

 

[uberswede]

Ripped it apart today, tried finding a gasket somewhere... no luck.... so used the copper grade RTV for now, and so far, it seems to be holding up. I think it might already be blowing out, but we'll see.

That was definitely a major part of the issue though. Now that I have somewhat of a gasket, the car seems to scream, and I've barely turned up the boost. Like 10+ in 1st gear, 16 easy in second, then 3rd, I keep blowing a vacuum line off at the intake manifold.

But yeah, damn. This is MUCH better. I'll be ordering a proper gasket tomorrow for when this rubber stuff inevitably blows out, as it's only rated to "700 *F, intermittently"... which, I'd imagine an exhaust manifold will likely exceed more than just "intermittently"... but we'll see!