Supercharged 3800 V6 motors are good, but a turbo version is even better! (Image/Richard Holdener)

When it comes time to talk about engine swaps, the first motor that comes to mind is probably the GM LS.

Long the darling of the industry, the LS has all but taken over where (it might be argued ) the original small block Chevy left off. The LS-swap-the-world crowd has seen to it that the GM V8 has graced the engine bays of just about every vehicle imaginable. In fact, the swaps are not limited to just cars, but frequent marine and aviation applications as well. It wouldn’t surprise me in the least to hear that someone LS swapped a submarine.

As versatile, cost efficient, and effective as the LS engine family seems to be, there are obviously many other candidates that will (when properly modified) provide not just adequate motivation, but amazing performance.

In fact, it might be argued that it’s high time the trend setting, dare-to-be-different crowd find something else beyond an LS to swap into their favorite performance vehicle.

For the adventurous swappers (Fiero and S10 owners, I’m taking to you) or the great many factory applications, it is time to take a look at the supercharged 3800 V6 L67 and L32. Truth be told, we actually ditched the factory M90 supercharger for a more efficient turbo, but we will get into all that later.

For now, let’s take a look at what went into a 600 horsepower 3800 build up!

The GM 3800 V6 Engine

For those unfamiliar with the GM powerplant, you can think of the 3800 V6 as the replacement for the turbocharged (and legendary) 3.8L Grand National motor. Better in almost every way, the 3800 V6 offered improved head flow and a hydraulic roller cam, but ditched the intercooled turbo for an Eaton M90 supercharger. Rated at 240 hp, the L67 was soon replaced by the 260 hp L32. The additional power came from revised heads and an improved (Gen 5) version of the Eaton M90 supercharger.

What makes this 3800 V6 so desirable is not the use of the M90 supercharger, but rather that it was designed and equipped for factory forced induction. In fact, elimination of the (power limiting) M90 roots blower gives way for the amazing power potential, thanks to a low-compression short block that will take significantly more power than the factory ever dreamed of. It is not unheard of to double or triple the factory rated power output of the 240 to 260 hp using the stock bottom end.

Upgrading and Turbocharging a GM 3800 V6

For our build, we were looking to top the 600 horsepower mark, a goal we easily achieved using a cheap turbo and few essential (and one non-essential) mods.

With a power goal of 600 hp, the first step was to replace the M90 supercharger with a more efficient and powerful form of forced induction. Off came the M90 supercharger and on went a cheap GT45 turbo. Capable of supporting over 750 hp on the right application, it offered more than enough flow for our 3800.

The GT45 was teamed with a Procharger air-to-water intercooler. The combination resulted in a much lower charger temperature than even an intercooled version of the M90 supercharger.

Rather than just add boost, we decided to further improve the power output of the naturally aspirated 3800, as gains made NA are often multiplied under boost. To that end, we decided to augment the 3800 with ported heads, a healthy cam, and a revised intake (to replace the blower). We had a local machine shop surface the heads, perform a valve job, and do some mild port work.

In anticipation of the cam upgrade, the heads also received a set of 26918 beehive valve springs and matching retainers from Comp Cams. The spring seats on the iron heads were machined to accept the new springs and produce an installed height of 1.75 inches. Once set up, the heads were installed with new Fel-Pro head gaskets and stock head bolts, but MLS gaskets and ARP head studs are on the way for the future (high-boost) runs. The modified heads were run with the factory roller-fulcrum (like an LS) rockers.

The machined and ported heads were teamed with a new cam profile from ZZ Performance. The ZZP NIC cam offered 0.507 lift (intake and exhaust), a dual-pattern duration split of 220/230 (at 0.050) and 112 degree LSA. The cam was run with the factory hydraulic roller lifters and stock pushrods.

The finishing touches included use of the factory L67 lower (blower) intake topped with a gutted M90 blower housing. To produce a suitable upper and lower intake, we removed the rotor pack and made a cover plate to seal the upper intake. All the boost from the intercooled turbo system blew through the stock L67 throttle body and gutted blower housing into the lower (short-runner) intake—a better choice for street use would be the long-runner 3800 V6 Camaro/Firebird intake.

3800 Dyno Testing & Results

Run in naturally aspirated trim, the low-compression 3800 V6 produced 267 hp and 247 lb.-ft. of torque.

Run with the DIY turbo kit (using the stock FWD exhaust manifolds), we first applied 7.6 psi from the intercooled turbo setup. Run on pump E85 from a local station, the turbo 3800 produced an easy 418 hp and 387 lb.-ft. of torque.

Raising the boost up to 12.6 psi resulted in 534 hp and 488 lb.-ft. of torque.

Eclipsing our goal of 600 hp required 14.55 psi, where the turbo V6 pumped out 612 hp and 556 lb.-ft. of torque. It is at this point we started thinking seriously about adding ring gap, MLS head gaskets, and ARP head studs to the combo before getting serious!

Imagine what this motor would be like swapped into a little S10 or Fiero!

This graph clearly indicates that combining a modified 3800 with boost from a single turbo can produce amazing results! After upgrading the junkyard L67 3800 with ported heads, a ZZP NIC cam, and gutted M90 blower housing, the power output of the low-compression 3800 increased from 215 hp (stock) to 267 hp. The combo was then treated to a single GT45 turbo and Procharger ATW intercooler using the factory exhaust manifolds. Running just 7.6 psi on E85 resulted in 418 hp and 387 lb.-ft. of torque (a gain of 151 hp). Cranking up the boost to a touch over 12 psi resulted in peak numbers of 534 hp and 488 lb.-ft. of torque, while 14.55 psi brought 612 hp and 556 lb.-ft. of torque. The factory M90 supercharger could never duplicate this combination of power and boost. Now it just needs to find a home, but before that-it will see even more boost! (Dyno Chart/Richard Holdener)
The test motor started out life as a Series 2 L67 3800 V6. It is also possible (and maybe even preferable) to start with the later Series 3 L32 version. (Image/Richard Holdener)
The first step toward making more power from your supercharged 3800 V6 is to remove the factory M90 supercharger. (Image/Richard Holdener)
To further improve the power output of the 3800 under boost, we subjected a set of L32 heads to porting. Testing showed that all our porting efforts generated very little in terms of power, but properly ported heads should work well. (Image/Ricahrd Holdener)
One upgrade that was definitely beneficial was the addition of a set of 26918 beehive springs and retainers from Comp Cams. The ZZP cam required the increased spring rate. (Image/Richard Holdener)
Because we ditched the M90 supercharger, we needed a suitable intake. Though the best choice for a street turbo system would be one of the long-runner NA intakes from the RWD Camaro (for proper TB orientation), we relied on a gutted M90 supercharger case. (Image/Richard Holdener)
After removing the rotor pack from the M90, we made this cover plate to seal the intake under boost. (Image/Richard Holdener)
The factory PCV system required drilling and tapping to plug two holes in the intake. This eliminated pressurizing the crankcase under boost! (Image/Richard Holdener)
For our turbo application, the gutted M90 supercharger case was run with the factory throttle body/MAF assembly—no MAF was used for tuning. (Image/Richard Holdener)
The gutted upper intake and stock TB was installed on the L67 lower intake. (Image/Richard Holdener)
The simple, DIY turbo system consisted of nothing more elaborate than the stock exhaust manifolds feeding a single turbo. For dyno use, the turbo relied on this 3.5 inch downpipe. Obviously, this turbo system would need to be configured to fit in your chassis. (Image/Richard Holdener)
To provide boost, we relied on this ultra low-buck, (generic) GT45 turbo. Capable of supporting 750+ hp, it was sized very well for our modified 3800. We plan to push it even more in the future. (Image/Richard Holdener)
Keeping things cool was this Procharger ATW intercooler core. Oversized for this mild turbo 3800, it was run with ambient dyno water and kept the charge temps below 100 degrees under boost. (Image/Richard Holdener)
Boost control came from a single 45mm Hyper-Gate wastegate from TurboSmart. (Image/Richard Holdener)
Rather than try running the factory ECU, we relied on a Holley HP management system. This system allowed us to tune the 1500cc Snake Eater Performance injectors running E85. (Image/Richard Holdener)
Run first in NA trim, the modified (low compression) 3800 produce 267 hp and 247 lb.-ft. of torque. (Image/Ricahrd Holdener)
After adding boost from the GT45 turbo set up, the power output jumped to 418 hp at 7.6 psi, then to 612 hp at 14.5 psi of boost. Who wouldn’t want a 600+ hp V6 powering their S10 or Fiero Swap? (Image/Richard Holdener)

Keywords
3800, Richard Holdener, turbochargers
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Author: Richard Holdener

Richard Holdener is a technical editor with over 25 years of hands-on experience in the automotive industry. He's authored several books on performance engine building and written numerous articles for publications like Hot Rod, Car Craft, Super Chevy, Power & Performance, GM High Tech, and many others.