3800 SC mods?

EyesofThunder

New Member
Joined
Jul 3, 2008
What sort of mods do most people do to the 3800 SC's?

I have a 00 Park Ave Ultra with the F41 package and I have done some PCM tuning and gutted the stock very restrictive air box. The upper end pulls very well.

I am still concerned with mpg like probably most people who drive 750 miles a week just to get to work and back, but a smaller pulley would be nice, that and maybe a higher flow muffler (it has 1 main and 2 rear).

Fortunately the Park Aves (my guess is all C&H bodies don't have it) don't have the dreaded U-Bend the W bodies have.

I would love to get into the 13's, but need to keep some degree of reliability....
 
The best I have gotten out of my 02 GTP w/the 3800 SC engine so far is 13.8 @ 99mph. There are several sites that have tons of info on them.
Here is some info from one of them

This should be a quick down and dirty to the ever present question. When can I run a 3.4, 3.25, 3.0 etc.... Take into account this write up will be on the more conservative side and I think everyone will agree that this aplies to 95% of GTP's. Obviously that 5% applies to people with already hurt motors or if you have 150k miles, have gone 10's of thousands of miles between oil changes etc... you may want to rethink modding at all and start fresh. With this list you should be knock free, however its always a good idea to either buy a scantool or join one of your local chapters and find someone close by with one to scan for kr, however like I said this list is designed to almost guarntee 0 KR.Anyone please feel free to addin suggestions or comments and I will adjust this accordingly.

Well start with the 3.4 pulley as it usually starts the majority of these questions. Below you will find a list of supporting mods that should be in place prior to installing that 3.4. Can you get away with less? Possibly. Have people gotten away with less? Yes. Do you want to take the chance? Enough said.

1. PCM- standard v 1.0 will suffice at this level.
2. CAI/FWI- Cold Air Intake/ Fenderwell Intake, you can build your own or purchase one from a vendor.
3. Ported Exhaust Manifolds/ Headers/ ZZP Powerlog- your choice, at this level Pems or the Powerlog are fine, if your planning on further modding later you will need headers, only you know your budget.
4. 3" Downpipe- Crushbendt which most exhaust shops will do is unadvised, preferable to purchase an aftermarket from one of the vendors.
5. 1-2 Heat range colder plugs. i.e Autolite 104's or equivelent gapped in the .050-.055 range
6. Ubend delete- just after the cat, most exhaust shops will be able to remove this and put in a straight pipe.

Thats it, doesnt sound too hard right? Fortunatly your reading this, back when alot of us blew our motors there was no such write up and no such guidance. These 5 items are considered necissary, of course you can change your thermo to a 180 unit, also wouldnt hurt. Also quite a few people add a set of 1.9 ratio rockers to that list. If you plan on staying at this mod level, I agree, add the rockers, if your planning on continuing on in the quest of more speed and wont be at this level for very long skip the rockers.

Now onto the 3.2-3.25 Pulley. Obviously this is going to take more extensive supporting mods. Add all from above and include:

1. Camshaft- take your personnal pick, do a search these have been compared time and time again. Addin supporting components, i.e stiffer springs, new pushrods, check with the vendor for individual needs.
2. Ported and Polished heads, larger valves- check with the vendors on this one, will be your best bet to invest in a stage 2 or 3.
3. Headers- if you had Pems before your dangerously close to being out of their level, sell and get some headers.
4. Larger Throttle Body- again these have been compared, take your personnal pick.
5. 2-3 heat range cooler plugs, you can stay with 104's but may need to switch to 103's
6. Retuned PCM to add in the cam and free flowing heads etc....

3.0 Pulley needs extensive mods, and honestly you shouldnt even be considering if you have to read this, but just in case take all from above and add:

1. High flow Cat
2.Cat-Back system
3. 42.5# injectors
4. Upgraded fuel system
5. Stage 4 heads
6.Powertuner/HPTuners or some other means to custom write onto your PCM during a dyno session.

Now yes notice I didnt say anything about Intercoolers in any of those combinations. Either a Short Stack or Full size intercooler obviously adjusts those combinations. However I dont agree with the idea of just slapping on an IC to address an issue. Can you run a 3.25 with a full size IC and no other supporting mods? Our vendors say yes. Will you get knock? No probably not. Is it a knucleheaded way of thinking? Abso***inglutely. Go ask people who have dealt with forced induction far longer than our motors have been around, if they would almost double the stock boost with just an IC backing it up, not a single one will say yes, Ill bet my next year salary on it. IC's are great, and have their uses, but you need to have a foundation first. Endeth the sermon.


try clubgp, full throttle v6, and 3800 pro
 
Nice post! Any chart like the LT1 guys had on what combo did what on the track? Somewhere there is a sweet database of times, cars, owners, and list of mods. Not commerical like dragtimes, just good html list. LOTS of cars.... From 16's to single digits.....

Any indication of when the trans says too much and gives up the ghost? How reliable is the 4T65E? I have a 4L60E in my Fleetwood and it is at 250K and still shifts great, (ok, special HD tow package one) and hasn't been rebuilt yet. Shows what GM CAN do if they want to....
 
Nice post! Any chart like the LT1 guys had on what combo did what on the track? Somewhere there is a sweet database of times, cars, owners, and list of mods. Not commerical like dragtimes, just good html list. LOTS of cars.... From 16's to single digits.....

Any indication of when the trans says too much and gives up the ghost? How reliable is the 4T65E? I have a 4L60E in my Fleetwood and it is at 250K and still shifts great, (ok, special HD tow package one) and hasn't been rebuilt yet. Shows what GM CAN do if they want to....

I have the HD trans in my GTP, at 125K miles it still shifts great. I hear its kinda a roll of the dice on the trannsmissions, but I havent had a problem yet.
 
I have a 97 ultra with the 3.4 pulley and I remember running in the high 9's in the 1/8 mile
 
a pulley will not reduce gas mileage...only your right foot

on long hauls i typically get 30mpg at 75-80mph.... city 40% and highway 60% i get 24-25mpg.
if i drive nicely around town i can get 20mpg, but i usually get 17-18mpg

with a home-made airfilter(k&n cone) and a 3.4"pulley i ran a 14.3 at 97mph...absolutely no affect on drivability.

i bought a 2.5" "downpipe" off ebay for $69 bucks and a ZZP SS intercooler.....ran a 13.8 at 99mph

i've since removed the intercooler, added headers and bought a tuner....feels much better on the highway

alot of the stuff you read on those websites is garbage....you'll end up with an empty wallet and a bunch crap on your car
 
leave the mufflers alone....only thing i would change is the downpipe.

if you already have a tuner...you can get your fuel trims tight and bump your highway/cruise timing up a little for better gas mileage
 
I wouldn't mind a pulley, but afraid that I will lose mpg, I drive a lot of highway cruising, mpg is important. I guess maybe I will just have to try.... I have seen as high as 160 kPA on stock pulley (that is around 8.8 psi boost). It runs decent, can't complain, but would love midrange/upper end. I have a hacked up airbox that allows a lot of air in and I see only around 6-9 degrees more intake air temp than ambient (as read by the PCM sensors and the climate control temp sensor).

a pulley will not reduce gas mileage...only your right foot

on long hauls i typically get 30mpg at 75-80mph.... city 40% and highway 60% i get 24-25mpg.
if i drive nicely around town i can get 20mpg, but i usually get 17-18mpg

with a home-made airfilter(k&n cone) and a 3.4"pulley i ran a 14.3 at 97mph...absolutely no affect on drivability.

i bought a 2.5" "downpipe" off ebay for $69 bucks and a ZZP SS intercooler.....ran a 13.8 at 99mph

i've since removed the intercooler, added headers and bought a tuner....feels much better on the highway

alot of the stuff you read on those websites is garbage....you'll end up with an empty wallet and a bunch crap on your car
 
what kind of gas mileage do you see now?

i saw better fuel economy after the air filter and pulley...
 
especially where you are asking about an ultra K shef has been there & done that allready and has given you great advice.

the list of supporting mods for pulleys posted above is good provided you verify knock retard is not present with a scanner/tuner , but where a lot of buick owners would tend to be on this forum if they are modding a regal gs you will require more exhaust mods than listed as it is the only L67 car that came with a single muffler in addition to the wonderful u bend.

I have always wanted a GN but until then I am having fun with L67's , they respond wonderfully to mods and there are cars running as fast as 9.0 @150 on stock(never apart !) short blocks. Depending on how clever you are a set of dr's and under $500 in mods can get you in the 13's under $2k can get you in the 12's and so on & so forth and the cars are plentiful & cheap to buy:cool:
 
A nice 3.4 pulley set up would feel pretty good. There is so much you can do just make sure you have supporting mods to keep the KR down. These L67's like to chip pistons if you get too greedy:D :D
 
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