Modding the Supercharged 3800 for Dummies

[Imp558]

my car wasn't available supercharged nor is there a hell of a lot left of what GM intended for it to be. there is a certain Pride that comes with a car that didn't exist

[Nas Escobar]

Hmm interesting. I may have to look at it and seriously consider it... so I'd still be 9.3:1 compression? I thought the compression was based on the head gasket which you could get thinner or thicker depending on how much compression you want. How low of a pulley could I run? Guess I should probably make a thread about looking into this.

 

 

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The main difference between the L36 and L67 blocks are the pistons. Everything else is the same, except compression on the L67 is 8.5 compared to 9.4 on your L36. That's why a top swap makes more sense. You could probably get the whole setup at Crazy Ray's for $150. Most people surprisingly leave the L67's alone, and they're in abundance at the yards. If not a W, they can come off an H body. I'd just double check that the p/n's for the injectors are the same, but they should be. I think L67SS is running an H body motor. His Monte is pretty frankensteined

 

As far as smaller pulleys, most people go down to a 3.4 pulley. 

 

I think I'm gonna leave it. I'm making about the same whp that a stock GTP is making crank. I also don't like the idea of it being a fake GTP. I'll get a GTP eventually but I think the top swap isn't something I should do

 

 

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It's not a fake GTP and at the end of the day, the trim is just a marker for the engine. There was nothing special about them. It's not like taking a V6 Camaro and turning it into an SS with the SS specific spoiler and other random tidbits. 

 

my car wasn't available supercharged nor is there a hell of a lot left of what GM intended for it to be. there is a certain Pride that comes with a car that didn't exist

 

THIS FTW. 

 

I did something similar with my old 2002 Camaro. My 3800 had a hole in the block and I swapped it for the L26 engine out of a 2008 Lacrosse. Long story short, you think a stock engine with some mods is satisfying but when you upgrade to something better, and actually use it, it makes you smile. I know the L26 and L36 aren't very different but I do feel the bigger exhaust valves made a difference... along with the full exhaust setup I had on it. I had upgraded from 2.25 to 2.50 and deleted the EGR. 

[Grandprix1]

The main difference between the L36 and L67 blocks are the pistons. Everything else is the same, except compression on the L67 is 8.5 compared to 9.4 on your L36. That's why a top swap makes more sense. You could probably get the whole setup at Crazy Ray's for $150. Most people surprisingly leave the L67's alone, and they're in abundance at the yards. If not a W, they can come off an H body. I'd just double check that the p/n's for the injectors are the same, but they should be. I think L67SS is running an H body motor. His Monte is pretty frankensteined

 

As far as smaller pulleys, most people go down to a 3.4 pulley.

 

 

It's not a fake GTP and at the end of the day, the trim is just a marker for the engine. There was nothing special about them. It's not like taking a V6 Camaro and turning it into an SS with the SS specific spoiler and other random tidbits.

 

 

THIS FTW.

 

I did something similar with my old 2002 Camaro. My 3800 had a hole in the block and I swapped it for the L26 engine out of a 2008 Lacrosse. Long story short, you think a stock engine with some mods is satisfying but when you upgrade to something better, and actually use it, it makes you smile. I know the L26 and L36 aren't very different but I do feel the bigger exhaust valves made a difference... along with the full exhaust setup I had on it. I had upgraded from 2.25 to 2.50 and deleted the EGR.

Heads alone are $100 and I would have no way to take a motor and even do anything with it by myself. I could probably get everything off of it but I could take a whole motor.

 

 

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[digitaloutsider]

The main difference between the L36 and L67 blocks are the pistons. Everything else is the same, except compression on the L67 is 8.5 compared to 9.4 on your L36. That's why a top swap makes more sense. You could probably get the whole setup at Crazy Ray's for $150. Most people surprisingly leave the L67's alone, and they're in abundance at the yards. If not a W, they can come off an H body. I'd just double check that the p/n's for the injectors are the same, but they should be. I think L67SS is running an H body motor. His Monte is pretty frankensteined

 

As far as smaller pulleys, most people go down to a 3.4 pulley. 

 

The engine block itself is the same for an H-body, but the oil pan, oil filter adapter, mounting system, pullies, brackets, etc are all W-body specific.  Injectors and fuel rail are the same.  I would not pulley down to a 3.4" on a topswap without headers at the very least, and even then I wouldn't move that far down until I was at maybe a 3.6" and scanning wielded no KR.

 

 

Heads alone are $100 and I would have no way to take a motor and even do anything with it by myself. I could probably get everything off of it but I could take a whole motor.

 

I would never pay $100 for junkyard heads that I'd have to take somewhere else to be gone over anyway.  Your best bet is finding an individual parting out a car a wrecked so you can see it run for yourself, then take the parts you need.  Honestly, troll the 3800 Marketplace group on Facebook, I'm sure plenty of people are sitting on a complete top swap.

The advantage of pulling it yourself is that you KNOW for a fact everything is there.  I know myself, and probably other folks on the group, might be willing to take some time to visit a yard with you and help collect the parts you need.  Hell I've got an L67 LIM and perfect condition M90, so that gets you almost halfway there.

[Grandprix1]

The engine block itself is the same for an H-body, but the oil pan, oil filter adapter, mounting system, pullies, brackets, etc are all W-body specific. Injectors and fuel rail are the same. I would not pulley down to a 3.4" on a topswap without headers at the very least, and even then I wouldn't move that far down until I was at maybe a 3.6" and scanning wielded no KR.

 

 

 

I would never pay $100 for junkyard heads that I'd have to take somewhere else to be gone over anyway. Your best bet is finding an individual parting out a car a wrecked so you can see it run for yourself, then take the parts you need. Honestly, troll the 3800 Marketplace group on Facebook, I'm sure plenty of people are sitting on a complete top swap.

The advantage of pulling it yourself is that you KNOW for a fact everything is there. I know myself, and probably other folks on the group, might be willing to take some time to visit a yard with you and help collect the parts you need. Hell I've got an L67 LIM and perfect condition M90, so that gets you almost halfway there.

That's a good idea. I'll keep my mind on it and keep looking at parts and see what people are doing. I'd love to run boost but I can't afford the cost haha

 

 

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[l67ss]

One thing to remember when looking at the horsepower ratings is where its making it. Just because two motors make the same peak HP doesn't mean they'll run the same. Once you add boost it becomes a whole new animal. And x2 on trolling the fb 3800 pages for parts. I've seen complete topswaps as cheap as $80. Something I also noticed was I picked up mpg....especially around town

[Grandprix1]

One thing to remember when looking at the horsepower ratings is where its making it. Just because two motors make the same peak HP doesn't mean they'll run the same. Once you add boost it becomes a whole new animal. And x2 on trolling the fb 3800 pages for parts. I've seen complete topswaps as cheap as $80. Something I also noticed was I picked up mpg....especially around town

The top swaps that are that cheap are they on the car or off the car and I just need to pick up a box? If I could do this for 80-150 bucks then sign me up. If it's a full motor I won't be able to do that cause I got no where to even put a motor much less store another another.

 

 

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[Imp558]

It's more than that, head gaskets alone are pretty pricey. Set a realistic goal date and gather parts. Watch for deals and update your cars build thread so everyone knows what you still need.

A top swap doesn't have to be crazy expensive but as with any project things add up, like $25 for supercharger oil for instance. There's no reason why you can't have the engine parts for about $100 but you really should have the heads redone and that's $200 at the place I use.

[Grandprix1]

It's more than that, head gaskets alone are pretty pricey. Set a realistic goal date and gather parts. Watch for deals and update your cars build thread so everyone knows what you still need.

A top swap doesn't have to be crazy expensive but as with any project things add up, like $25 for supercharger oil for instance. There's no reason why you can't have the engine parts for about $100 but you really should have the heads redone and that's $200 at the place I use.

That's a good idea. It would be very expensive regardless because if u want to be able to run decent pulleys you'd need to change pistons since the compression is higher on the NA cars. At that point your better off just buying a GTP.

 

 

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[digitaloutsider]

What on earth are you on about?  You don't have to change anything, just don't go balls to the wall with dropping pulley sizes. My old '98 is STILL running around, nearly 100k miles later on a used L36 block with a 3.4" pulley and the necessary supporting mods and no KR.

 

It really is as simple as dropping L67 heads on to an L36 block. There is no magic or mystery here.

[l67ss]

Yeah no need to change pistons. Just have to do more supporting mods with each pulley drop. The higher compression alone will make a topswap more powerful than an l67

[Grandprix1]

Ok well I joined the 3800 sale site on Facebook so if I see any top swaps there for a nice price I may jump on them. 

[Imp558]

I'm planning an L36 bottom end for my "final" engine

[carkhz316]

Lots of good info. Not sure if this is proper place to comment, but my own takeaway from top-swapping, that not many have ever mentioned, nor is there much info on, is the subtle year to year and platform differences with engine components. I am specifically noting that there are alternator and alternator mounting changes between '98 and 99 on all platforms; also the A/C compressor and mounting bracket are different between platforms too. I'm not sure why, but the SC belt would rub on the A/C compressor until I put a small enough idler pulley and belt to clear the AC comp. 

 

Also, if anyone would like to give me a crash course on Fuel Trim/ O2 tuning that would be great. I know my way around HPT a little bit, but the tune I'm using in the Monte is a clubgp member (can't remember who, some Adam guy)-modified ZZP tune. It runs fine all around and gets decent mileage (don't really pay attention as the car hasn't been taken on much for road trips), but holy cripe it smells like a old farm truck (rich exhaust, though no black smoke); and my LTFTs are always hovering around -20%. Any help can PM me or comment. Thanks!

[digitaloutsider]

That is a good call out, at some point I need to try and compile that data (alternator mounting, vacuum line routing, etc) between the years. 

 

As for the tune, those are massive negative LTFTs. Do you have a wideband? Stock injectors and MAF? What mods?

[Imp558]

It would be cool to have a really good guide on tuning, Shawn did a write up a while back but it assumed the reader was familiar with the software.

[digitaloutsider]

I would love if someone with a lot of tuning experience would sit down and write us a guide. But you're usually gonna run into someone who only uses DHP or only uses HPT and doesn't know how to translate between the two.

 

A lot of the "tuning guides" and "tuning notebooks" that exist out on the Internet are extremely outdated or wrong. For example, both Gary's Guide and Jerry's Notebook reference doing VE tuning. VE tuning is a complete waste of time (outside of having a failsafe tune on an extremely modified car to get home if the MAF dies) because of how the 3800 PCM calculates fueling. Tuning a car for VE is extremely time consuming, wastes gas, and produces zero benefit. So the recommended starting place by most "expert" tuners is to start with MAF tuning. And even then you'll have people who debate whether or not you should touch the MAF table (Editor's note: A MAF tune was absolutely necessary on my car, I saw no other way around getting fueling right). Another example: neither of these guides discuss lowering the KR enable temperature, which in 2017 is known to be an important step before you accidentally make the engine go boom because GM set the original temp too high.

 

Then there are people who are fluent in GM LS PCM tuning and try to apply that knowledge to the 3800 PCM. Same for people who studied Greg Banish's book over and over. Greg's shit is SPOT ON for LS tuning, but sadly much is useless for ours. For example, if you want to tune an LS car to run E85, you literally change one table that references the stoich number of the fuel. That's it. You're done. In HPT for 3800s, that field exists. Except it doesn't do anything. Little things like that are what make tuning our cars difficult because everything is a little tidbit of knowledge or a trick or workaround and no one seems to know them all. You have to read every single bit of information you can and try to figure out how it applies to you. I spent more time than I care to admit just comparing BIN files to try and figure out why some changes were made.

 

At the end of the day, I think a lot of 3800 tuning is guesswork or working off of "known best practices" and hoping for the best, hence a lack of any real updated tuning guides.

[carkhz316]

That is a good call out, at some point I need to try and compile that data (alternator mounting, vacuum line routing, etc) between the years. 

 

As for the tune, those are massive negative LTFTs. Do you have a wideband? Stock injectors and MAF? What mods?

No WB, but I'm running stock L67 injectors and 99+ MAF and throttle body. Aside from the top-swap, the only mods are FWI, and 284 swap. I can post/ email my HPT file if that would help.

[bluegtp91]

OP:  You're the first one ever to actually site where it came from and give me credit (even though I know the post is like eight years old); I appreciate it.

 

Also:  Hi people.

[digitaloutsider]

Hey man, good to see you around here! But it's no problem at all.. I've had enough people hijack my shit over the years. I wouldn't do that to someone else.

[bluegtp91]

Hey man, good to see you around here! But it's no problem at all.. I've had enough people hijack my shit over the years. I wouldn't do that to someone else.

 

Gimme a holler if you need anything; PM's usually work since I'm still trying to fix GPF after Devil's Own basically told us to take a hike.  I'd have no problem shooting advice to people around here, too.

 

However...the Corvette takes up a lot of the free time lol

[Marshal]

is there any hp gain to be had switching to a 3" exhaust? I currently run sd headers with a 2.5" downpipe.

[digitaloutsider]

Don't the SDs have a 3" downpipe?

[Marshal]

i'm not sure if they do or not, I just know mine is 2.5"

[pshojo]

Nice