Just curious as I'm nearly decided on buying a 1996 Buick Riviera w/superchared 3.8 ....if I knew I could do some easy mods to get it to 250+ HP that would be cool. Does it have an FMU or what ......how does the factory address fuel pressure vs boost? If it's an FMU setup it would obviously be easy to put a smaller pulley on the blower as long as the factory timing is conservative. What about K&N FIPK? Flowmasters? (on a Riviera ....lol, nah prolly not)

Check this out .....I can get it for $3,000 because it has high mileage and minor hail damage and some minor fixes needed. It has a motor from a wrecked 1999 Park Avenue Ultra that only had 12,000 miles on it though. It needs minor work like A/C charging and leak repair, sunroof motor is making grinding noise and needs a helping hand, hail damage repair (paintless dent repair) will be $1,000 without fixing the top or $2,000 with fixing the top (not much area to fix but hard to get to). I think I will buy the car and fix everything but the top because it's not that bad anyway and not worth $1,000 to fix to me. My mechanic has already checked it out and everything else is great on it ....says he would completely rebuild the tranny for $1,200 if it became neccesary (due to high mileage) but it works great for now and tranny fluid is a nice color. The dismantler/rebuilder who put the motor in used the old SC from the bad high mileage engine because the one from the newer engine had external fire damage .....my mechanic checked it out and said it's all superficial damage and he could clean it up and paint it....swap it in for a few hundred or less. Reason for swapping it is the old SC's coupling has some play in it which the rebuilder hadn't noticed.....you can twist the pulley and there's half an inch of play before it moves the blades. The newer SC feels tight and great just looks bad on the outside. Anyway, looks like I could have the car with everything fixed but the hail damage on the roof for about $5K maybe even less. Everything else is perfect, all of the power stuff works and factory leather interior is mint. Brakes/tires/underbody/shocks/body/paint/stereo/traction control = all great! These things stickered for $35K .....I'm thinking really nice daily driver for $5K, what do you all think? BTW, back to the original question ......what mods are good/easy/safe?

 

Go to http://www.clubgp.com/newforum/ and sign up so you can post to the forums. There are a lot of people there that could tell you about this motor. I wouldn't paint the SC because they are real picky about heat.

It sounds like it could be a fun car. My Z is my play toy but my Grand Prix, with a similar SC 3.8 as the car you are looking at, runs pretty good. My friend has a 4.6 Mustang and he is scarred of my car now, LOL.

Good luck

 

My GTP is reliable as hell AND hauls a**. I put down 233 hp to the front wheels with a 3.25 pulley and a fenderwell 9" K/N. That equates to 290hp at the flywheel. I've put 28,000 miles on this car (55,000 total)since I did those mods, I still runs great and I beat the heck out of it on a daily basis.
I bet it would run a high 13 at around 99mph on a good day.

 

Fireman, that's awesome! You're telling me a simple pulley and filter upgrade will give you nearly 300 HP on the SC 3.8 !? That's pretty damn good. What do you have to do supporting mods-wise? Does it have an FMU from factory or what? What about the timing ....do you use a BTM or something or does the factory computer remove timing as boost comes on anyway? Now I'm really getting interested The only thing that disappointed me about the Riviera's performance was the part throttle performance wasn't so snappy and the tranny's a little slow on kickdowns ......not bad, but just not impressive. Does pulleying up make a noticeable difference in part throttle response or do you only notice it when you're getting on it?

Talk about a nice sleeper car/daily driver .....a mid to low 14 second Buick Riviera, totally cool!

JWBerk94Z, why not paint the SC? Because it could hold heat in? I assume my mechanic was talking about some really durable engine enamel or something? He said he'd dip the charger in chemicals to get it clean and replace the seal in it near the pulley just to be safe; he was thinking of painting it only for cosmetic reasons upon resale.

 

The factory PCM adjusts for everything, just change the pulley, put on a K/N canister and go!
Heat kills performance though, I have installed a drilled 160 thermostat to keep things as cool as possible.
My first time to the track I ran a 15.2 @ 91 mph, then I hot lapped it and ran another 15.2 @ 91(this is with a 3.4 pulley and an open K/N mounted to the throttle body)
I let the car cool for an hour and ran a 14.7 @94 mph, I let it cool for another hour and got 14.64 @95 mph. I have learned some tricks since then:
Run it till almost empty,put race gas in, reset the computer, drive around for an hour or so. Doing this, the computer re learns everything(timing advance, etc) on race gas. This is supposed to be worth a couple tenths.
After putting on the 3.25 and mounting the K/N in the fender, I was short on time. I reset the computer in the pits and ran it immediatly after, that when I got the 14.45.
Several people told me that I probably lost half a second from not letting the computer relearn anything. Someone even said "its like being forced to run with a broken leg". This is why I believe it is really capable of a 13.9 at around 99mph. Check out clubgp.com

To fix the transmission shift firmness, rpm and kickdown you will need a DHP or Digital Horsepower PCM(around $300). This Pcm is supposed to be worth about 15 wheel hp as well. I have also removed the plastic cover on top of the supercharger because it retains heat. Remove the weatherstripping near the cowl to allow underhood heat to escape as well.
You do not need any boost retard devices as this engine was supercharged from the factory, they don't reach the ignition or fuel system limits till 400wheelhp or so.

 

I have read on Clubgp about people painting their SC. Usually this is frowned on by most of the more knowledgable guys there, because of heat. You don't want anything to slow down heat escaping the motor. These cars have knock sensors like or LT1's do. Only a SC is more prone to detonation/knock due to the heat caused by compressing air. You don't have to run a btm because the factory pcm senses knock and pulls timing out. Fireman may be able to run a little faster with a bigger pulley. From what I have read it takes a lot more mods to get exhaust out than he has before the car doesn't pull a lot of timing with a 3.25" pulley. I am not saying his car is set up wrong or anything. I would just suggest that you read up on clubgp before you start putting a pulley on your car. My gtp is pulling up to 5* of timing out right now and I have a 3.4" pulley and a high flow Downpipe/Cat.

The DHP PCM's that he is talking about are great. That will be my next mod.

These motors are fun. My car has had me distracted from spending money on my Z for a couple months now. However, after I buy my DHP it will be time to make the Z faster again

I cant stress how good of a resource the forums on clubgp are. You really should make a post there for advice. I am far from a good resource on these motors since I am only a couple months into modding my GTP. For instance I am curious if there are any differences in our motors. I think yours is the Series one and mine is a series 2. Probablly no big deal, but there may be better mods for one than the other. Don't know

Good luck and don't forget about your LT1

 

I used to run the top of the line MSP catback with a 3" ID resonator to centered Y split to dual 2 1/2" Hooker areochambers, I saw no difference with this kit except for the sound, KR stayed the same when I went back to stock exhaust. I keep the car very cool and monitor everything with my scanmaster. The factory downpipe is the worst, it is double walled, it looks like 3" from the outside, but ID is really more like 1 1/2". And of course the restrictive U bend in it as well. I used to run the Random Tech 3" SS offroad downpipe, It never sealed right and I always got an SES light even with the rear O2 sim, the SES light pointed to the front O2(?) I tried replacing the front O2 and nothing changed. I went back to the factory downpipe and no more sealing problems or SES. I did however have the U bend removed and replaced with a piece of 3" pipe.
I'm sure I would have gotten around 240 wheel HP with that DP if I could have gotten the SES to go off. 3.25 is safe with only a canister if you don't beat on it in the heat, even if you do, you won't harm anything as the PCM will just pull lots of timing. I picked up 3 mph over the 3.4 pulley with the 3.25, once again, when the motor is cool and KR is down.
If you want to run consistently fast, the DHP is the way to go. My friend ran consistent 14.20s at 98mph the other night with a DHP,CAI, and a 3.4 pulley, stock exhaust.

 

I have a GTP that runs mid 13's (13.5-13.6) at 103 with a couple of bolt ons (rockers, pulley, downpipe, cutout).. it's scary the amount of torque it put out when I put it on the spray.

 

JWBerk94Z, I see that you're from B-ville!! You ever head down to Kanawha Valley??? We've got a little local crew that likes to race down there on thursday nights (well, all I do is watch now that I sold the LT1). You should come, it's cool meeting people from the boards.

Charlie, it sounds like you could be dustin' my "built" 305 with minimal effort out of the little 3.8. Please dont do that to me!!! Talk about wounded pride! Later!

Joe.

 

How's it goin' Joe. Is Chris Detamore part of your local crew? I used to work with him and just recently got back in touch due to this board. I need to get back to the track, I have only been once since I bought my car and it was nearly stock then. I wouldn't mind getting my little Pontiac up there once too. I am a little curious how it will do.

By the way, why did you sell the LT1? I watched your buddy run a Supercharged Mustang with it out on Rt. 2 not too long ago. Man that thing looks fast.

 

Yeah, Chris is part of the crew, but he only makes it out a couple of times a month due to work.

I sold the LT1 on a kind of spur-of-the-moment type deal. Sean (funina91ss) was very interested in the car and I wasnt driving it (keeping it babied in the garage for winter), so it just seemed liked the right thing to do, and I dont miss the payments not one bit! Plus, it gives me the opportunity to build up the '91 and make it a real head-turner, it's a work in progress. Maybe one day it'll be as fast as the '95 is now. Sean has the car running 7.50's on the bottle, and 8.10's without. It bested a 7.69 on spray and an 8.59 NA when I owned it, so he's made some excellent progress with the car.

Hope to see you at KV one thursday!!! Let us know if you plan on going! Later.

Joe.

 

JWBerk94Z, I didn't even notice you are in our area ....cool! Hopefully we'll run into each other at the track sometime.

Joe, I don't know if the Riv would be quite as fast as your 91 but it might be close and a fun race though.....we should consider that if I get it!

Fireman, some of the stuff you are saying concerns me a bit. Why are you guys so casual about knock retard on the 3.8? The sensor pulling out timing is not a good thing, as that is after the fact so you are seeing real detonation first and then the timing comes out to prevent more. Also, if the PCM relearns on race gas and makes better power output doesn't that mean that you just had more retard before due to it learning that the gas you were using just wasn't up to par? To me that sounds very risky and is a sign it is pullied too much to be safe on pump gas. Unless the factory PCM works differently than I'm thinking and rather than operating on set values it advances timing until detonation and learns to stop the advance right before that point. I checked out clubgp and they say a 3.5 inch pulley is the best for optimum balance between torque and HP due to the low adiabatic efficiency of a roots blower at high boost/heat levels. From their dyno tests it looked like changing to the 3.5 pulley alone makes a huge difference in and of itself. How much difference do you all think the K&N and higher flow exhaust makes? I think for a Riviera I would want it to stay somewhat quiet, so maybe a high flow cat with the downpipe mod you all are talking about, and maybe the quietest flowmasters money can buy. As for the K&N is there an FIPK or is it more popular to just bolt a cone filter onto the throttle body?

I know the compression ratio is only 8.5 so that is good, are the pistons forged as well? How does the DHP make extra power, via leaner tuning? Also, can it eliminate the top speed limiter like a Hypercrap?

I noticed someone on clubgp sells shift kits for the tranny, I would probably go that route when/if rebuild time would come for it as it has 116K miles as far as I know.

 

Keep in mind, this motor was built for the supercharger and the stock PCM was programmed for a supercharger as well. These cars have a very conservative program stock. They had to make this car stand up to wifes and grandmas who floor it going up a hill in the summer on pump gas, this motor was designed to take the abuse of the blower even with people who don't anything about KR and premium gas. I you still wanna hammer it everyday in 110* heat and boost performance a little, the 3.5 is for you. I never floor it unless I am at the track or it is fairly cool outside. Even if you do get crazy hre and there with the 3.25, the ringlands aren't gonna go anywhere, this motor is bulletproof.

 

Huh, I never looked at where you were from, small world. Do you run your car at Kanawha Valley?

Hey Joe, I work evenings so I won't be at the track much. I will be off on Thurs. July 17. The plant where I work is shut down that week. So I will try to get up there then, if I can't make it sooner. I don't know which car I will bring. I drove the Z yesterday and figured that it was time to order a clutch. Then today it worked pretty good. Time is ticking, LOL. If I don't have a new clutch by then I may have to see how the GTP does.

Canboufo, check out this article. http://www.zzperformance.com/zzp/inf...rd/kr_home.htm

It explains a lot of things like the dhp pcm, kr and so on. It is really informative. ZZPerformance is also a very good 3.8 performance shop.

I am not sure about the Buick's stock exhaust. Supposedly the stock GP exhaust flows great once you replace the downpipe. They look 3" on the outside but they bevel (sp) down to something like 2.1" on the inside. So I would say that a highflow downpipe/cat would be a good idea. Does your car have dual mufflers? Flowmasters are gonna give you that crappy 60 degree V6 sound. Ever hear a V6 camaro with a flowmaster? My downpipe made my car a good bit louder with stock exhaust. But, some people like that sound. It's just not for me.

I would just go with the 3.4 Well, I did.

As for the cone filter, I don't know if you can get a fipk for that car. If you just bolt a filter on then it will be sucking in warm air. Some people do it, but you want it as cool as possible. Make a post on clubgp to see if anybody knows of a cold air for this car. You could also make a custom one. This link is to make a fwi (fender well intake) for a GP but I am sure you could do something similar. http://www.azgrandprix.com/fwi/

I believe the pistons are forged, but don't quote me on that.
The link to the article at zzp above explains how the dhp makes power. The dhp does eliminate the speed limiter. As for the shift kit, most people running a dhp say you don't need one. It increases line pressure somehow, which makes the car shift harder.

 

The Riv has dual mufflers and is really, really quiet ....I can't really hear the exhaust at all, the only thing you hear is the engine sucking air when you floor it. I would guess it has the same restrictive downpipe and the cat with 116K miles on it is probably a restriction as well. I think I would replace both and leave the mufflers stock from what you are saying about the flowmaster/V-6 sound.

As to choosing the best pulley size you all have me scratching my head, I think more research is in order or maybe I should just compromise with the 3.4 pulley. However, JWberk94Z....you said you are getting KR with it and that would bother me. Maybe the 3.5 is what I should go with because I don't want to go crazy with it and have to monitor with a scanner and all of that (been there doing that with the Z and it gets old IMO). With the 3.5 pulley it sounds like I'd get nearly the same increase in performance (especially with CAI, downpipe, etc) and not have to worry about KR. I don't want to spend a lot on mods and want to be able to just drive the car anywhere and drive it hard at times without worrying about it. With the 3.5 pulley and nothing else at all, what do you think the flywheel HP would be ....... 275? If so, that would be good enough for now and I could do the DHP, intake and exhaust, etc later. The DHP sounds like the way to go since it can do more than just power increase. Does it run on a set "power-program" like Hypertech or does it have different levels of fuel and spark to compensate for different pulley sizes? If it can compensate for a smaller pulley size with less ignition timing then I might consider the 3.25 pulley

I guess I've got some reading to do but in the meantime share as much info as you care to guys, thanks for the info and links.

PS: Also, two important questions. 1. Who has the best deal on pullies 2. Do you really need a pulley/seal removal tool to swap the smaller pulley in?