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3.8L Build

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v6 build
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25K views 16 replies 6 participants last post by  Injuneer  
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#1 ·
Hi Everyone,

I have been modding my Brid one piece at a time, small gain by small gain. So far I have done:

CAI
160 Degree Thermostat
Pacesetter Headers
3" Magnaflow Exhaust Catback
Cat-Delete
3.42 Posi Rear End w/Rear Disc Brakes
Founder's Lower Control Arms
Founders Panhard
UMI Sub Frame Connectors

I have been learned from many of you on here for many years now, and thought I would give something back to the community. After bouncing a lot of ideas around here for a while now, form LS1 Swap to L67 w/M80 Fabrication... I have narrowed the idea of my build and decided on a direction to go to build up my 97 3.8L Firebird. I love my car but it is lacking severly in the power department, as we all know these cars don't put much out without some serious work and money. I would like to take my 3.8L to LS Stock Territory. Its possible, but not easy and I have a plan, so here it is:

1) Grab a Grand Prix Supercharged Engine Bottom End and Fuel Injectors
2) Send this bottom end out to a local rebuilder for a refresh, I don't have full shop access so this will be sourced out to the pros.
3) Pull Top End off a L36
4) Send the Heads into Intense for Stage 3 Service (Port & Polish w/Upgraded Internals)

Also Purchase the Intense Perfomance Package:

INTENSE™ 3800 Camshaft
JP Performance Single Chain Timing Set
LS7 Hydraulic Roller Lifters
INTENSE™ Oil-Restricted High-Performance Pushrods
ARP Head Stud Kit
Cometic/INTENSE™ .052" MLS Head Gaskets
L36/L26, L67, or L32 Cam Installation Kit
GM Timing Chain Dampener
INTENSE™ Rocker Installation Kit
INTENSE™ Custom Powertrain Control Tune

5) Custom Tranny Teardown and Rebuild with upgraded Stall Converter
6) Powerdyne Supercharger or Custom Turbo

I was not very keen on Turbo because of the possibility of AC Delete (NOT HAPPENING IN FLORIDA), and the ugly tubing under the engine.
However I have been seeing some real nice custom tubing done (a little coating can go a long way!!!)

From all the people in the field I've spoken to, with the mods I've done and all these improvements running 8 psi boost (All say it is more than safe after these mods with no risk) will get me to 300 HP at the wheels. I've been told that I COULD push it to 10 psi, but any higher I would need to go forged pistions... others tell me that the bottom end could handle 400 HP all day long. I'm not racing or anything, just want to nice running car with a kick that I can pop the hood and be proud of.

I will be posting progress reports and pictures as I go here. I don't expect to have this all complete until a little later next year, but anything is possible.
 
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#3 ·
From all the information I gathered on the GM Engines (L32, L67, L36, and L26) none of them contain forged pistons. The L32 have powdered metal connecting rods which is by far the strongest and can take some serious HP... pistons are a different story. There is a huge misconception about boosting and Forged Internals, its not always a requirement. Its really a balancing game between Compression, Boost Levels, and Tuning. The reason the L32's and L67's are able to run a supercharger and not blow the engine is that they have lower compression 8:5.1 where as the L36 and L26 N/A's run 9:4.1. The Boost Levels in the M90's don't go above 8 psi (GP Pros correct me if I'm wrong here), this is considerably low for boosting levels and a Supercharged Car producing less than 300 HP (260 HP Stock at the most I'm not mistake) is proof of that. The reality is that the L32 and L67 are capable of producing some MASSIVE POWER, 240 to 260 HP is what the GTP's run stock there are many accounts of people Building their L67's from the cam up only and putting down 350 to 400 HP. Stage 2 to 3 Heads and cams, bolt-ons, with 12 to 14 PSI (which I consider a little risky) will get you in that area.

With that being said, the L36 which is used in the N/A Grand Prix have M90 bolt on kits that many 3800 Shops sell them that offer considerable gains with supporting mods. This is achieved safely by running lower boost levels, upgrading to L67 Heads (I beilieve P & P is a must with this), fuel delivery, and PCM Tuning... all while keeping he Higher 9:4.1 Compression Ratio. What this says to me is the Series II and Series III are very powerful engines, capable of much more than we give them credit for.

My desired output is in the 300 to 330 HP range (285 to 290 at the wheels),

I believe with:

L67 or L32 Bottom End

Built up Heads and Cam

P & P Intake (Upper and Lower)

GTP Fuel Delivery

Rebuilt Custom Tranny and Stall Upgrade

and Boosting between 8 to 10 PSI and professional tuning will get me in that territory.

Experienced builders please correct me if my research is inaccurate here.

Now if I was planning on running 12+ psi with a Shot of Nitrous, I would throw Forged Pistons in there.

Hell, I may do it anyway. If I get a call from the shop on the rebuild/refresh and they tell me it will be $800 extra and a few extra days wait, that would be an option worth paying up for.
 
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#6 ·
I hear you, and if the price is right I will go Forged, but I'm not going to break the bank or push back my whole build for budget concerns on that. Its not a high priority for what I'm looking for. If was insistent on Huge Horsepower gains I'd be planning an AC Delete, and Twin Turbo... and would be Sweating My Butt off in the Florida heat with only momentum to cool me. I'm just looking for a rewarding build that gets Stock LS1ish output, that I can gun it on long highway drives here and there... It will never see the track, and maybe only see a dyno if I get curious or need some better tuning.
 
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#7 ·
Update:

So far I got some Junk Yard Parts off a 97 Firebird:

Upper Intake Manifold

Lower Intake Manifold

Throttle Body

Valve Covers

Fuel Rail

Its not much but a start. I'll just be cleaning everything up real nice, and maybe a nice primer and paint for the UIM and Valve Covers and polish up the fuel rail so it looks nice. I also am going to polish the manifolds and smooth grind and seal up the coolant bypass in the Throttle Body Chamber (Live in Florida... no need chance of any freeze in there). I will post pics of what I'm doing in the near future.
 
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#9 · (Edited by Moderator)
Spent a little time on the Lower Intake manifold during the holiday break, cleaning and port and polish.

It was a major trial and error process in cleaning them up. Degreasers, carb cleaners, brake cleaners, wouldn't do a damn thing... I found a magic solution that worked great:

Liquid Laundry Soap (Wisk), Hot Water and a few Brushes (Nylon to get started, then wire to finish it up)

A few cone sanding cones from Harbor Freight, and lots of hours.

Then some fine sanding/finishing discs for the ol Dremel.

Not expecting any impressive gains form this work, just wanted to get some experience. This was not as difficult as I expected, just very time consuming and labor intensive... it has me considering doing the heads now.
 

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#10 · (Edited by Moderator)
What i would recommend with the heads is use a gasket to make the ports on the intake and heads the same. Port matching and removing casting flash is the key. It will remove areas that fuel/air can get caught and slow velocity into the combustion chambers. With a supercharger/turbo in a direct port fuel injected motor, it really doesn't matter as much, as it deals more with pressures and less with the flow patterns. BUT, smoothing casting flash will allow liquid fuel to flow easier into the CC. I don't have a ton of experience actually porting, but i do understand the physics and aerodynamics behind it.

I will be doing the same intake/head work on my wife's 2000 3.8 bird in a month or so during the rebuild. I will not be going boosted however

My recommendation is sticking with 8-10psi with stock L67 internals. If you are going to be running higher or using NOS, i would recommend forged internals if you want your investment to last.

Also, get the pistons/rods balanced, as the manufacturing process causes them to be pretty far off. This causes rod bearing to wear out quickly at higher rpm's and knocking occurs.

I don't know if you will get a full 300 hp out of this combo, i think the deciding factor will be the camshaft. A conservative cam probably won't hit the mark. I would like to see where this goes though.
 
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#11 ·
The Gasket Sharpie/Method is the only way I know, the Youtube videos simplify it so much, that is why I'm considering doing the port and polish myself. Im getting some L36 heads form a youpull yard at a steal (40 a piece), then putting some upgraded internals (130 Lb Springs, Retainers, Rods, Spacers Ect)… If I foul up a head in the process, then its not a major loss.

As for bottom end, since I'm way a head of my build schedule, I can be patient and wait for a L32 bottom end, which has stronger internals. Still not forged pistons, but stronger than the L67. The Grand Prix forums I have asked boosting questions they all say 10-12 PSI all day long on a freshly built and tuned L32 bottom end. L67 6-8 PSI, safely 10 would be pushing it. Not very many of them felt safe beefing up the boost on a L67. I will be pulling the bottom end, sending to a machine shop and letting them do their magic, not a corner worth cutting.

The Camshaft I'm going to be running is a Stage 2 Blower cam, don't have the exact numbers but it is a good compromise between performance and drivability. I will also be putting in a 3000 to 3800 Torque Converter to adjust to this. No nitrous, and the GP guys are excited to see this as well (their lack of RWD limits them a bit), they all agree on 300 HP and a little north on this build with a proper tune. I have pacesetter headers and 3 inch full exhaust for this reason alone already on it.

The only X Factor is the Powerdyne Charger, they aren't designed to boost over 6 PSI reliably, but with the people at 928 Motorsports I may have to bite the bullet and get their full custom rebuild to make 8-10 and built to last. They said if I pulley it to the max AS-IS, with my planned mods, I will see easy 300 HP, but they can get me to 340 without a problem.

At the end of the day, these are all numbers. I'm not taking it to a track, just want a nice fun build with, and didn't want to sell it and buy a LS1. So far I have come in under budget on what I have collected, and this is only because I've kept my eyes open and been patient.
 
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#13 ·
Grand Nationals are very hard to come by, either very few were made or their owners hold on to them for dear life. Grand Prix GTP's on the other hand are fairly plentiful, L67's everywhere and a few L32's are popping up here and there. I am only pulling out bottom end portion of the engine, because I am building up the L36 Heads and keeping the L36 Firebird/Camaro LIM and UIM's. Doing this gives me the 8:5.1 Compression Ratio optimum for low to mid boosting (6psi-12psi), and I won't have to do any crazy fabrication, just upgrade fuel... tune... and go.

From what I have heard the L36 bottom end can support 300 to 350 HP, L67 is 400 to 450 HP, and L32 450 to 500 HP.

L36 9:4.1

L67 8:5.1, Stronger Rods

L32 8:5.1, Forged Rods

Add Forged pistons to the L32's, I'm sure 600 HP is very possible.

Just repeating what I have been hearing multiple times from legit forums.
 
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#14 ·
Update:

This build is taking longer than I really wanted it to. Both Finances and Time have delayed this build but not canceled it, I am still in the parts collecting phase. The only change I have decided to make was to keep the 9.4:1 Bottom End, after running a compression test on my Bird and confirming we a good to go there. After reading many reports and forums, I decided that I don't really need to pull the bottom end of a Grand Prix GTP if I'm going to keep it around 5 - 7 Boost PSI and run a proper tune.

So far I have collected:

L36 Heads from a 2002 3800 Series II Camaro

Valve Covers from a random 4th Gen Firebird

Fuel Injectors form a L67 Buick Regal

I have also placed my order from Intense for:

105# Valve Springs

Retainers

Valve Locks

The valve springs are out of stock, and will be able to expect them sometime November. Obviously I am not ready to build it up right now, so no big deal. Once the parts arrive, I will be sending it out to be cleaned and then I'll do the Porting and Polishing and of course adding Photos here.

When I pulled the Fuel Injectors today, I made sure to cut and keep the wire connectors, just in case they don't match up, just eyeballing it, I believe I am fine. I will be cleaning, testing and putting in storage with my Intake Manifold.

Can anybody tell me what rating the stock L67 Fuel Injectors run at?

I believe they are either 32 or 36lb. If anybody knows form sure, please let me know.
 
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#15 ·
Ok, the Collecting continues, So far I got:

#105 Springs

Retainers

Valve Locks

Seals.

LS7 Lifters

Reusable Rocker Arm Bolts

Rollmaster Single Timing Chain

all from INTENSE Racing.

To this point I have settled on the Stage 1 Intense Blower Cam, and Lightweight Push Rods. I sent an e-mail about this decision to the guys at Intense. They have been pretty informative to this point, so I am laying my trust in their hands.

I am now shopping for a L26/L32 bottom end.

Also during my search, I am in the market for rocker arms. From what I have read, I don't really need to invest in upgrading the rocker arms since I am going the boosting route, stock ratio is the only way to really go.

Does anybody know if I can pull rocker arms off a Grand Prix, Regal, or anything with a Series 2 or 3 Engine? It would be 1000 Times easier if I could pull Rocker arms off a FWD car. I haven't found anything about rocker arms being interchangeable. My educated guess is that I can, based on the fact that the Series 2/3 heads are interchangeable since you can pull L36/L26 and make it work on the Firebirds. Since I am putting in an Aftermarket Cam and Supercharger,
 
#17 ·
“wav6644” was last seen on this site 5 years ago.
 
Prev. Owned 1994 Firebird Formula
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