View Full Version : To those with a 10% blower pulley

Scott Long
04-07-2003, 07:52 PM
I just had a bunch of work done to my SC and now its reading very low vaccuum. At idle it sits at the C on VAC. Thats like 3 inches of vaccuum. But the car doesn't idle rough. I thought maybe the bypass was sticking and I checked all the hoses and the bypass valve and its fine. So whats the deal? I doubt my gauge just messed up all of a sudden.

The car goes into boost VERY easily now but I'm only seeing about 10 psi on the floor. I do have a very free flowing exhaust (catless down tubes, flowmaster force 2 resonator and mufflers).

The upper IC tube was removed so we could get at the power steering pump to change the high pressure hose but I think its sealed well since its not stumbling at idle or anything.

Any ideas?

04-07-2003, 08:19 PM
I got a 94 tbird with a full exhaust and ported heads, with my 10% the gauge just to sit right at 20 at idle. Now I got a vac leak some where and it sits just a little above 20. So I think you got a serious vac leak, is your blower really loud? I would check that. I also get about 13-14 psi almost instantly. Hope this helps a little.


04-07-2003, 11:38 PM
If all else is normal then I would say that you have a leak at the tube that runs to the gauge. That's about the only thing that would make since, especially since your boost is so low for having a 10% pulley.


Scott Long
04-08-2003, 12:09 AM
I raced a GTP last night and from a 40 mph roll. I was in 3rd and we both jumped at about the same time. I held even with him for a little bit and then he started to walk away from me. I was only seeing 9-10 psi of boost. Even with my exhaust I was hoping to get about 13 psi out of this car. I am going to reseal the upper IC tube this weekend when I get to St. Louis.

The car feels a little faster than it was, but not much. For what I paid to get this work done ($4048.57) I was hoping that the car would perform better. I had the transmission and rear end rebuilt along with new shocks, eibach springs, new bushings and control arms, clutch and all components, fuel pump, exhaust, blower pulley, and gears. The car is quick but I think it should have more pull.

The GTP has a chip, 3.2" pulley, and an intake. He got 2nd when he floored it, I had mine in 3rd. I might have done better if I would have dropped to 2nd but I don't like beating on my car.

How can I have a vac leak but the car runs fine, idles fine, and doesn't throw a check engine light? Also my cruise control hasn't worked since I installed my new cd/mp3/dvd player. I was moving stuff around in the dash but I don't recall any vac lines behing up by the radio. I had to cram a lot of wiring in there though to make it fit. Since the DVD player had two big black boxes to fit in the little opening and the tv's power supply had to fit up there too. I'm so pissed right now. At least it runs and I can drive it.

04-08-2003, 12:15 AM
Because it's probably right at the nipple and is just enough to throw the gauge off but not enough of a leak to cause it to idle rough. I blew the line off of mine and it idled like a champ. Other than the hissing and no gauge display It was fine. It doesn't really matter how good your exhaust is you will still make 14psi with a 10% pulley.


04-08-2003, 12:52 AM
Are you still running the stock inlet pipe, MAF and TB? I don't think it would cause a loss of 15ish inches of vacuum, but it could make a difference. When I had a SCP inlet pipe, I had about 16 inches with a cam and a modified ESM Dominion III blower spinning an 18% OD. Since I changed to a MAC CAI, it's up about 2-3 inches to 19 or so.

I'd check for leaks at, on or around the blower by spraying some carb cleaner around the joints. If there's a leak, it'll change the idle. Then follow the line for the gauge.

As for how it runs, only the pulley, exhaust and gears added power. A wild guess of 25-30 HP from the pulley and exhaust and .1-.2 in the 1/4 from the gears depending on what you went with.

See ya,

Scott Long
04-08-2003, 02:16 AM
This is my mod list (drivetrain/motor):

9" K&N cone filter
SCP intake tube (aluminum)
70mm MAF w/o bridge
10% overdrive pulley
removed cats
flowmaster cat back
190 lph fuel pump
3.27:1 gears
ripper shifter

Everything on this car is new except the engine which had the head gaskets done right before I bought it.

What would you estimate my power at? I'd be happy to see 215 rwhp but I don't know if thats a high estimate on my part?

Randy N Connie
04-08-2003, 11:21 AM
here is my mod list,& RWHP number

Scott Long
04-08-2003, 10:39 PM
sprayed with carb cleaner today, no luck.

tightened up some clamps on the cross-talk tube. Got a little more vac and 1 psi more boost. Now I'm getting 9 psi. No rough idle. Beat a Z28 on the way home from work tonight. Still low on boost and vac. Gonna reseal the upper IC tube saturday.

Scott Long
04-09-2003, 06:28 PM
Any ideas where else I might get a vac leak, I checked the boost gauge hookup, and the bypass valve hookup, i'm out of ideas.

04-09-2003, 06:34 PM
Pull the boost gauge out of your other car and see if the one you have might be damaged. Stranger things have happened.


04-09-2003, 07:32 PM
I assume this is your 92 sc. Im sure you have read some of the other posts about the 10% pully puling timming out and whatnot but with your mods I think you should running faster. Our 93 dosnt get but 10-11 on the boot-o-meter and I have pulled my hair out to find nothing wrong. I think that with the milage on the car about 125k or so has a lot to do with it. The only thing that bugs me is you say you lost some boost over night. I would check all vacume hoses with a 2 foot vac hose held up to your ear. this short of a stethescope is you best bet. I have seen some of those litttle plastic hoses split and cause minor leaks, cant even see the split. I myself am going to get a dyno tune by the man after all my mods are done. I think this is most important because the comp just dosnt know we are pushing more air and fuel. Well good luck Scott and let us know how its going.

04-09-2003, 09:54 PM

Scott Long
04-09-2003, 10:24 PM
The car gained about 1 psi and about 5 inches of vac. when I tightened the clamps on the rubber tube between the inlet and return plenums.

04-09-2003, 11:54 PM
Oh man I did that on the 93 when we reinstalled the motor I forgot to tighten one side and some oil deposits were showing up. I cant beleave the thing even ran at all. Ops. All I can say is vernon you are the man. Some day I hope to be that inteligent. I got some pressureising to do. Thank You

David Neibert
04-12-2003, 10:29 AM
This is Scott. I'm at Daves house in St. Louis right now for the SC meet. Yesterday when I arrived Dave helped me seal up the motor. It only took us about 15 minutes and we did it in the driveway.

Todd Jelle let us use his SC Collar nut spanner wrench and that collar nut took about 2 good turns to get tight. Then we tightened up all the intercooler tubes which took about 2-4 turns on each nut. After that we removed my cross talk hose and put caps on it, since the hose had a good cut in it. After all that the car pulled 3 inches of vac. Then we noticed the boost gauge line was cracked and leaking air. So we cut off the end, took some small vac hose and made it work. Then we zip tied all the vac hoses to keep them on the motor.

Fired it up and it idled a lot better, and now sits at 20 in. of vac at idle. Since Tony Serno is parked behind me right now I wasn't able to drive it to see how much boost I gained. I have a feeling it should get 13 to 14 psi now.

I want a rematch w/ that GTP....

We are getting ready to go to Stegemeiers to Dyno, so I will get to drive the car soon. Right now Dave's wife Kathy is making us all breakfast. The driveway is full of SC's, and we are gonna go see what kind of numbers we can pull.

Can't wait to see Mendola's ride on the dyno.

-Scott Long-
1992 Thunderbird SC 5-speed

04-12-2003, 03:41 PM
Well that makes since, glad you fixed it.


04-12-2003, 04:22 PM
Well??? what were the results? all better???:confused:
We're all pullin for ya

04-12-2003, 05:53 PM
Somebody get some group shots while you're at it. And..for what will probably happen tonight. ;) Anxiously waiting to hear everyone's numbers.