First post, but I've been reading up on this engine for years and years by virtue of having owned two L67s since 2007. Yes, I've been through all the stickies. I'm thinking of pulling the trigger when the weather warms up, and I want to have the stuff and the plan good and ready to go. I keep running into the "If you give a mouse a cookie" problem, though, which I'll outline below.
There are two major complications to this project:
- The car in question is a 2004 Buick Park Avenue Ultra. The GM C Platform is very, very similar to the H Platform (Bonneville), but I'm afraid of differences in the firewall or undercarriage (for example) that would make things like headers or downpipes incompatible. An example that comes to mind - the Bonneville uses a different length supercharger belt than the GTP, and that seems weird to me, since it's the same engine. Also: wbodystore.com --> okay.jpg
Welding would solve this.
- This is my daily driver. I would obviously do this over a weekend and probably take a few days off work as well. This complication is mitigated by a close buddy who is a certified GM mechanic. HELLS YEAH!
On to my mods list: Here's what I have in my ZZP cart so far.
- ZZP PCM - Because I'm probably not spending $500 on an HP Tuner, unless my buddy wants to do that, then I'd do like $200 of it and let him keep it. All options stock.
- 160* Thermostat - Because why not. All the reading I've done indicates the 2004s should have 180 or hotter, but I'm pretty sure that's for the GPs with the L32 motor. I have an L67 with a Gen3 blower.
This will just kill fuel economy
- TR8 Iridium spark plugs - Because I'm not changing these damn things every 6k. For the colder thermostat.
These will foul every 6K on a near stock engine. You don't put colder plugs in for a colder thermostat, if anything, you'd put in higher temp plugs. But the reality is, every 50-100 hp if increasing boost or compression to get it go one step colder. For most lightly modded 3800's, 605's will idle nicely and help keep it running a little cooler. 104's/TR6's won't idle as nicely.
- Power log and off-road down pipe - Fix the stupid U-bend (really, GM?) and front manifold; off-road because I can delete the O2 sensor code with the PCM and still pass emissions without a cat. I'd polish (and port?) the rear manifold myself. Decided on this combo over a set of Pace Setter headers for cost-effective solidness. Further, besides an incremental improvement, I can't really see what headers are doing for me over the combo of power log + polished rear manifold + down pipe. I've not been able to find much to this effect. I'd love to be educated on this.
Headers are going to flow better, let you run a smaller pulley, or use lower octane for the same pulley.
- K&N 4" x 9" filter - strap it right to the TB, because I read stickies.
Probably going to cause more KR in the city, bump fuel economy, unless it throws off your maf readings.
- MPS - 3.4" pulley and appropriate belt - 716? (Please help.) I'm pretty sure I can't go to 3.3 right off the bat, but if the scanner shows no knock, then... what? The PCM advances the timing by itself and I can judge whether or not to drop to 3.3? How does one know? Or do you just drop to the next pulley as soon as you have zero knock?
You're going to want to see if you can even run the stock pulley without KR first. If you have the ability to tune, you'd bump the timing up to 18-19*, if you can run that, you can try a smaller pulley at lower timing, say 15*. Repeat as necessary.
Anyway, that's my ZZP cart. No pulley puller yet, because I'm hoping to grab one off a forum like this. Comes to just over $700 so far. Maybe some of these parts are available used on forums and such, save me some bucks.
Now: here's where I run into the "give a mouse a cookie" bit. Everything I'm reading says I really want to intercool right off the bat, or maybe immediately after fixing the U-bend (seriously, GM). So:
I want to intercool. That means I want to machine out my lower intake manifold, and I probably also want to machine out my blower housing to match it, too. If I'm machining out my blower housing, I probably want to machine out the inlet port.
Unless someone has tested this, I can't see why the H bar would impact flow or outlet temperatures in the slightest. Its not sealed against the core, the air isn't going to make a 180* turn just to go to the furthest ends of the core. Natural order of things is to take the easiest, most direct route.
If I do that, I want a throttle body to match the new inlet port - Northstar throttle body.
You're nowhere near needing a larger TB.
Of course, I still need a cone filter to slap on that throttle body, and Mother of God, I'm pretty sure now they're going to hear my blower scream on Mars. Now, let's pretend I'm doing this right off the bat with no other mods. I know that stupid U-bend is there (UGH,
GM), so I'm going to want a down pipe. Now, this is a fine stopping point, since the power log is not as huge a fix as the down pipe, but I'd probably end up doing it anyway. All of this is probably enough to support a 3.2" or 3.1" pulley, and now I've run my injectors dry.Into the engine we go. Since we're in there, I might as well cam, and I'll do new springs and retainers, too, and a chain, because the car has close to 60k on it. Finish the job off with aluminum coolant elbows (because those damn plastic ones failed TWICE!! on my 2000 Ultra), and all of a sudden, I've sunk $5000+ into my car, and it's "Bye, kids, I'll see you next weekend, tell your mother to brush your teeth before school."
Forgot about the transmission investment to support that kind of power having to move around that much mass.
So I'm thinking my plan is this: sink the initial $700 I've laid out above, then intercool in a major $3500-ish project later on if I feel like taking that on.
Is there anything obvious I'm missing? Any alternate paths you would take?
Originally Posted by rafadavidc
