I have no low end!

[GnTooFast4u]

I've got an 85 GN that seems to be the slowest thing on the road on the bottom end. The car has a pts 9/11 3200 stall, pt-54 turbo, ported intake(v1 or v3? don't remeber the #'s) 218 cam, walbro 340 hotwired, atr 2.5" downpipe, catless 3" exhaust, msd 50 injectors and a 20 degree 93 octane chip from precision, ramcharger electric fans, cone K&N filter. f.p. is at 39 PSI and o2/s are in the 810-820 range. Running 16 pounds of boost. The convertor will probably only get to 2800 rpm. Do you guys have any idea what my problem may be? I can only make about 4 or 5 pounds of boost on the line and it won't even spin the tires when it launches. I was thinking that there may be too big of a cam and turbo on there but what do you guys think.

 

[cool 84]

You have a pretty big turbo. I had the same problem at first with my TA64. Most of my problem was in my tuning. Have a chip made that runs a little leaner on the bottom end. Check the usual like exhaust leaks, wastegate puck sealing, and the restrictor end of the vacuum "t" going the right way.

If you're running an elbow, even with the 2.5" downpipe it will hurt spool on a big turbo. I went from the Kenne-Bell 2.5" with a ported elbow to a Lee Thompson 3" that eliminated the elbow and it was a night and day difference in spool, not to mention power.

 

[GnTooFast4u]

Thanks for the quick reply. The car has absolutley no exhaust leaks, but i have not checked the wastegate puck or vacuum tee. Could you tell me how to check those? It also hase a manual boost controller, is there a wrong way of hooking these up? Thanks again

Paul

 

[cool 84]

The brass restrictor in the Y goes toward the compressor. The idea is to restrict overall volume to the wastegate/bleeder. As long as the restrictor is on the compressor side, you really can't hook it up wrong.

 

[fireberd350]

My car has identical symptoms as yours....a COMPLETE dog at the bottom end and will RARELY ever even spin the wheels. I need my POS tuned good tho, just need to find someone in my area who know hotairs.

 

[GNeric]

My 85 did this exact same thing. I have an 87ecm, Thrasher 108 chip, Poston 107 cam, BlueTops, TA-33, 3" downpipe, Hughes 10" 3000 stall. Turns out the converter came apart and one of the fins off the stator broke off and was wedging itself between the stator and impellar of the converter. Hughes wanted more than what I paid for it new to fix it so I had a shop here cut it open and repair it. Now the car has all the bottom end the Nitto's can handle.

 

[cool 84]

I know how frustrating it can be to have no bottom end. When I ran my car last time I had the gas floored while powerbraking and the boost guage wouldn't move at all. That's how I pulled my amazing 2.3 60. It wasn't a traction issue, I came out at WOT. Then, somewhere after the 60', right around second gear it would blow the tires away.

Slow spool is the reason I built this 4.1L with extra compression. Hopefully it will spool decently and so far it looks very promising. Unfortunately while my build was in progress the new GT series turbos came out which should spool much better for a given size.

FWIW, as a bandaid the turbo seems to spool better when it's hot. So don't shut the car off in the staging lanes. When I used to go out at night "hunting" I would drive the car decently hard all the time and when it came time to race it would definately spool better.

 

[GnTooFast4u]

I've never noticed any restrictor T, I've have to look for it to see if it's there. I guess if it's there then I'm screwed, I may have to get rid of the turbo for a smaller one, cause I can not live with no bottem end. Do electronic boost controllers do anything to help the spool up issue. I know there is a guy here in town that just blows his tires loose whenever he wants, not power braking either. That is what I want. It is an 87 though so maybe that has something to do with it.

 

[cool 84]

The restrictor Y is gray in color. It's common for them to get replaced with a regualr Y. A lot of people don't know there's a brass restrictor inside. It makes a huge difference with a big turbo. Aftermarket electronic boost controlers help spool. Even manual ones can help if you set them up right.

 

[GnTooFast4u]

Cool 84 I think you nailed it. There is a regular brass t with no restrictor on there. Let me run this by you to make sure I'm not mistaken but it's the only T i see in there. the hose coming from the actuator goes directly to the manual boost controller(black valve basically) on the other side of the boost controller is a another line that goes to the compressor, along that line is the T that seems to go to some sensor or something by the valve cover. Is this the one because it's just a regular brass T w/o a restrictor. Where can i get a T with the correct restrictor on it? Thanks again for all your help.

Paul

 

[turbobooster]

after readin ur guys replies i was curious to see if i can build boost at a dead stop powerbraking and well i barely get 2 or 3 lbs ive read some guys buildin up 5 or more now is that becuz they have there cars modified ? im runnin stock right now wit 3 in dp and dump so is that ok for wat i have so far or should my ride be able to build more ?(BTW tranny isnt in its best condition)

 

[cool 84]

Originally posted by GnTooFast4u
Cool 84 I think you nailed it. There is a regular brass t with no restrictor on there. Let me run this by you to make sure I'm not mistaken but it's the only T i see in there. the hose coming from the actuator goes directly to the manual boost controller(black valve basically) on the other side of the boost controller is a another line that goes to the compressor, along that line is the T that seems to go to some sensor or something by the valve cover. Is this the one because it's just a regular brass T w/o a restrictor. Where can i get a T with the correct restrictor on it? Thanks again for all your help.

Paul

Are you running a single line wastegate? I don't remember how the stock hotair is routed. Assuming you're running the single line wastegate, I would run the lines like the 87s did: The vacuum line comes off the brass fitting on the turbo compressor and goes to the restrictor side of the Y. One end of the Y goes to the wastegate and one goes to the wastegate solenoid (thingy on the valvecover). Very simple, just 3 vacuum lines. Since you're running the bleeder valve, put it in place of the wastegate solenoid. Solenoid is no longer used. Keep the electrical plugged in to the solenoid so it doesn't trigger the check engine light.

If you're not intercooled or intercooled and haven't moved the throttlebody to the pressure side of things, you'll need to run a vacuum line from the other nipple on the bleeder to a port on the throttlebody, assuming the bleeder has two nipples.

The Y can be bought from Kirbans, I believe. Watch your boost carefully the first time you get on it with it hooked up right. It will probably be way too high. It's probably a good idea to back off the wastegate adjustment or close the bleeder a little. I hope this makes sense, typing with a hangover is tough.

 

[cool 84]

Originally posted by turbobooster
after readin ur guys replies i was curious to see if i can build boost at a dead stop powerbraking and well i barely get 2 or 3 lbs ive read some guys buildin up 5 or more now is that becuz they have there cars modified ? im runnin stock right now wit 3 in dp and dump so is that ok for wat i have so far or should my ride be able to build more ?(BTW tranny isnt in its best condition)

If you're running the stock turbo, you should be able to make all the boost you want. On sticky tires, I would launch at 10 psi when I was nearly stock. I could've hit full boost just from powerbraking but anymore and the brakes wouldn't hold it back. I would check for the usual leaks before the turbo or vacuum lines to the wastegate.

 

[turbobooster]

wat r the usual leaks before the turbo i should look for ?

 

[cool 84]

Cracked headers, header to crossover, header to uppipe, uppipe to turbo. You should be able to hear leaks unless you're running open exhaust.

 

[racemybuick]

from what this sounds, I have a feeling the converter may need to be checked out. 16 psi for that combo seems modest...Have you tried any higher levels with any difference? What octane are you using? I have a feeling this is not a simple problem, and I hope when my car get's together, I can avoid this hurdle!

Good luck!

John

 

[fireberd350]

Mine also has a major knock problem...any ideas related to that?

 

[racemybuick]

Hey steve! long time no talk to! lol.

With knock, I have found it very hard to figure out. I had a non-turbo v-6 that had a distributor... When too far advanced, it knocked and pinged like crazy!!! So, for about a month, I was slappin 93 in it, and the knock was kept to a minimum, only on BIG hills, or foot to the floor wot... My dad came to me, gave me a wierd ass lookin wrench (distributor wrench), and said- "go retard the timing a hair"...I said how, and he told me to spin the distributor a tenth of a turn....just an itty, bitty, bit.... I did, and boom...knock be gone....

Anecdote....It is all in the timing! The chip you have may be leaning out the mix too much, and you are not getting the right mix....My only other suggestion is to check the timing, see how far advanced it is, and take it back a couple degree's. From there, keep notchin back until the knock is gone... I am not sure what chip you have, but if you explain the bad knock on pump gas to an a-hole, they will tell you go get alky or only fill 110+. That to me is not a solution, so I would try my best to find a chip that backs your timing off a wee, and see if the knock loosens up.

Are you burning any oil? Have you ever been a quart low? If yes, then boom...You got blowby, and that would knock the hell out of the car...But if not, you gotta tune it out!

I hope that helps any, Steve!

John

 

[fireberd350]

I run a Casper's thumbwheels on an 87 ECM on position 3. I actually run on pos. 3 b/c of the less timing.

Here's the specs on it:

 

[GnTooFast4u]

I can't find the Y anywhere, does anyone have one they want to get rid of? I called Kirbans and they sell the whole boost line kit not just the Y.