Smaller pulley in my '98 Regal GS

[jpstax]

I want to install a smaller S/C pulley in my 3800 Series II engine. My Buick dealer ordered the only pulley offered by SLP Performance Parts, the 3.5" diameter one. The dealer already has the S/C installation tool sold by SLP, so I'm having them install it for me. SLP claims the new pulley will add up to 25 more horsepower. Dealer also ordered an air temperature module which plugs in between the air temperature sensor and its harness connector. It tells the PCM to provide maximum spark advance (usually 1 to 2 degrees). SLP claims 5-7 horsepower increases are possible with this little device. I was wondering if anyone else has installed these two things, and if you've noticed a big difference in performance? Thanks in advance.

P.S. I also installed a K&N (flat panel) air filter for more power.

 

[JasonGS]

Welcome! Your sn sounds familiar. Are you on any other boards?

I would recommend visiting www.regalgs.org or www.clubgp.com there is tons of info out there for these engines.

To answer your questions, they are pretty much right on with the pulley. I wouldn't go any smaller than that unless you take out some exhaust restrictions and run colder spark plugs. Otherwise, you'll be getting some serious knock.

As for the air temp resistor thingy, that's a waste of $. As long as your intake air temp is below 120*F, you will see absolutely NO change in power whatsoever. The way the air temp spark table in the PCM works is that it adds no timing over stock at all. However, when the IAT starts to climb above 120*F, the PCM starts to slowly retard timing.

 

[jpstax]

New pulley and ATM device installed

I did it! I had a 3.5" SLP pulley installed yesterday at the dealer. The service manager said it would take a couple of days for the PCM to re-learn the new S/C boost capabilities. I asked him if I should disconnect the battery cable for a few minutes, to allow the PCM to re-set itself, and he said no. He said I just had to be patient and allow the computer to do its thing. He also said the ATM device does advance the timing 1-2 degrees, no matter what the air temperature is. It plugged into the MAF sensor. I'm anxious to see what kind of ETs I get from these mods.

 

[JasonGS]

Re: New pulley and ATM device installed

Originally posted by jpstax
He also said the ATM device does advance the timing 1-2 degrees, no matter what the air temperature is. It plugged into the MAF sensor. I'm anxious to see what kind of ETs I get from these mods.

Sorry to tell you, but he is either talking out of his ass, or he lied right to your face. Believe me, I have seen and edited the PCM code. Re-read my post above, it is accurate. It will only help if your IAT is > 120*F. Also, it doesn't plug into the MAF sensor, it plugs into the IAT sensor (intake air temp).

Oh, and btw, you'll be happy with the pulley.

 

[jpstax]

Ripped off

You're right. SLP's part description doesn't say anything about it advancing the timing only when the air temperature exceeds 120 degrees. What a ripoff! BTW, do you know approximately how much HP I gained with the 3.5" pulley and K&N filter?

Here's a link to the SLP page describing the device:

http://www.slponline.com/view_product.asp?P=63012

Thanks for the correction.

 

[steveX]

Jason a car with your mod should turn 400Whp+ in our shop. our on-IC normally make 330WHP. I must very good ET.

jpstax what kind of mod is done to the exhaust? you should be good with a 3.5 pulley, using the IAT spoof is also a good idea ONLY if you have NO KNOCK RETART. Be carefull using the spoof in 90 deegree plus weather, with the CTS running at 220 degree+ more boost+ hot weather+adding timing = disappering piston . i am not trying to scare, you should make sure the car is hook up to a scan tool. if you see any KR try colder spark plugs.

 

[jpstax]

Thanks for the advice Steve. However, you beg the question as to why SLP would risk selling a device that could cause piston damage. As far as I know, SLP is a very reputable company, unless somebody there didn't do their homework on engines. However, as a precaution, I'll disconnect the device on hot days.

I haven't done anything with my stock exhaust system yet. When I get financially ahead, I'm planning on eliminating the u-bend, which should help.

Do you have any idea as to how much horsepower I've gained with just the 3.5" pulley swap? SLP claims as much as 25 HP.

 

[steveX]

I agree with you ,SLP performance is a awsome company. I use alot of they 85mm (truck) 85mm LS1 mass air flow sensor on all our high HP application. I don`t know of any product that will hurt a motor.take a look at the product (GUNS), we all know the down side and the up side to the product, so there i side it.Product failer only occur when the installer/designer is not educated on a certain application. we get away with a lot of wild stuff in our shop. we are running solid roller cam in two supercharger car make near 400whp (non-IC). OH and you can forget the vacume brake.lol, Thank BUICK for the POWERMASTER . when i work with GFWC performane (comp cam) try too sell a lot of small block chevy grind in the 3800 roller cam. we use a different cam grinder with 40 yrs of cam design.

eliminte the U-bend is a big PLUS in exhaust performance. I don`t know what you furture is with his car, i know the guys Just keep comming back for more HP. I use to do alot of write up on the L67.NO more. you should also look into ported manifold. it`s the poor man headers .I think zzp performance sells them...PUUUU i can`t beileve i said that...LOL

 

[jpstax]

I just got off the phone with SLP. A technical advisor said to remove the Air Temperature Module, and get my money back from the dealer. He said I didn't need the ATM with the 3.5" pulley. He said the device is not designed to work with the pulley upgrade. Could cause KR. Thanks Jason and Steve for some good advice.

 

[jpstax]

More on SLP IAT module

I found another post (link) about the IAT "thingy". Here it is:

http://www.installuniversity.com/install_university/installu_articles/slp_atm/slp_atm_9.202000.htm

I feel confident it will be safe to reinstall the thing in my '98 GS.