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| Here, shiny shiny for you. Precioussssss.... |
The B-Body's LT1 has several areas that are known roadblocks to more power. The cam is one, the stock exhaust manifolds another. However, modifying either of those is costly (from the budget perspective, anyway) and of debatable legality where I now live. The cam's impact is a matter of choice, but as I've said, it's expensive to start messing with the exhaust manifolds, and you better get it right - the key to keeping the LT1 from going full on 'gas hog' is making sure the seal between the exhaust port and the O2 sensor(s) maintains it's integrity. Even then, it's a risk, though really it's not a Honda or Mustang or Camaro so roadside inspections shouldn't be anything I have to worry about. Sleepers just rock like that.
Still, there are several free to nearly so modifications one can perform when one is still stinging from the cash outlay that a new ride inevitably requires. They're a fine bridge to doing more serious mods and a great way to learn about your particular example while wrenching on it.
Throttle Body Bypass
Cost: FREE
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| If you look carefully you can see the black Gaff Tape Brand Hose Abrasion Protector installed as well. |
This mod is supposedly good for about 5 horsepower and seems like a good way to avoid detonation as well. While the heated throttle body itself wouldn't cause those conditions, under moments of stress it could certainly add to the thermal loads that would. No sense in 'blazing' a path for cold air to reach your throttle body, only to have said throttle body hot enough to heat it up anyway.
There is a hose on the front side of the coolant tank shown above. This leads to the throttle body, where it passes through and comes out the other side. I'd have some pics, but it's been many months since I performed this mod. The exit hose then leads to a hard line running to the back of the engine along the valve cover.
The forums usually suggest merely disconnecting these hoses, buying a brass fitting, and connecting them to one another. However I didn't see any reason to do that and leave a lot - a LOT - of slack hose getting in the way. So I simply bent the end of the hard line up a few degrees, shortened the 'send' hose, and attached it to the hard line. Wrap some Gaff Tape around the hose where it might rub against the alternator bracket.
Muffler Delete
Cost: $10
The Muffler Delete is a now-classic beginner mod for these cars. The factory mufflers are good for about 211 cfm of flow each. The 2.25" exhaust pipes can flow ~400 cfm each. The factory mufflers are a restriction, but does that necessarily mean they cost power?
Thankfully you can estimate this easily on this engine for the reason that it's based on such a classic. Typically small block V8s of this size and tune are happy with a ~650cfm carburetor. 211 x 2 = 422cfm, which means yes, the factory mufflers are costing power.
This is handy to keep in mind when the punters over in the four cylinder/import field suggest that you absolutely, positively must go for the penultimate, whizz-bang, extreme modifications possible. The muffler you install simply has to be almost no restriction at all, or you're just not cool or something.
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| "This the biggest one you got? It's got to match my giant NAWSSS tank" |
However if you were to install a pair of mufflers that were 'somewhat restrictive' but were capable of 400 cfm of flow each, you'd have enough flow on tap to keep the engine happy, not to mention the fact that the 2.25" stock pipes are only capable of that flow rate anyway. So unless you're going to revamp the entire exhaust system, 'race' mufflers installed in lieu of the the stock pieces aren't going to be more effective than the 'merely adequate' pieces - and are thus a waste of money, especially on a mild street engine that's supposed to be powering a hopped up daily driver.
The accepted consensus at the Impala SS forum is that the stock resonators, however, are effectively no restriction at all and many keep them when modifying the exhaust to avoid the dreaded 'LT1 drone' on the highway. This drone happens with about 1/3 to 1/2 of the mufflers out there without resonators installed on the LT1.
Many B-Body enthusiasts have taken the above information and deduced that you could do far worse than paying a local shop about 50 bucks to have them bend up and weld in some pipes to replace the stock mufflers, leaving the over axle pipes and resonators in their stock location. This does work and keeps a factory look.
However, when I tried to get this done on the West Side (west sIIIIIIIIIIDDE!) of LA, though, most of the shops, used to dizzy customers with too much money, quoted me a few ridiculous numbers for what I wanted done, and I decided one inspired (stoned) afternoon to take matters into my own hands. Thus the CID Vicious Exhaust.
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| No one is paying me for my Photoshop skills, so... |
I got two 2.25" adapters and two clamps at Pep Boys for 10 bucks. I reused the factory clamps on the back of the stock mufflers. I cut the resonators off of the over-axle pipes after removing them and 'simply' clamped the resonators onto the middle pipes of the factory system. In real life though I screwed up and didn't actually measure the stock exhaust. Up until the muffler exit on the stock system the ID is 2.25" as advertised, but the over-axle pipes and resonators are 2" ID. I ended up having to redneck it a little, which is to say I 'clamped the shit out of it' and fed the 2" pipe inside the 2.25" pipe to achieve a decent position and seal. There's a bit of leakage but not so much that you can tell curbside. Eventually I'll get proper 2.25" to 2" adapters on there, but in reality I'm probably going to order up a pair of Thrush glasspacks (perf-core and not louvered core, I've found out) in 2.5" size and mount them on the stock pipes a bit further up, and have turn outs fabbed up to exit in front of the rear wheels if I'm going to even screw with it. Unless I start running into clearance problems when I go to the lower profile wheels and tires I'm going to leave it alone until I can improve upon it significantly.
Honestly, I think this exhaust mod is all you need until you address the restriction at the beginning of the system, i.e. the exhaust manifolds themselves. If you're not running long tube headers I feel any investment in the exhaust beyond this is a waste of money. Oh, wait, I mean if you only care about horsepower and performance for dollar like I do - if you're a 'show car' type dude or an Impala SS owner I can understand your balking at this system. But if you care about performance for dollar spent, this 10 dollar exhaust system is hard to beat for flow, weight, materials used (everything aside from the Pep Boys parts are still stainless steel, which even some pricier aftermarket systems aren't), and even sound.
Some Impala SS guys hate this mod even when it's done with the welded in pipes - 'too much like a glasspack. Sounds like a redneck's car.'
But I'd have to agree with a random comment I saw on You Tube or one forum or another - "LT1 Roadmaster...a redneck's dream car."
So it's all six of one, half a dozen of the other if you ask me. Mostly, I get compliments on the sound, especially when I get on it. I'm biased, though. I've wanted to recapture the sound and aural sensation (shut up) of that header'd 327 screaming through glasspacks that powered my 'first car', the 65 Impala Convertible you don't know I used to drive because you didn't read my "Cars I've Known and Loved" post. Redneck? Well, we were in Florida at the time...
Again, if you've got more performance for less investment in either time to accomplish or money spent, let me know, but for me, this works. And yeah, I dig the sound. After years of sixes and fours, which are fun and great sounding in their own regard, I've wanted a V8's guttural growl under my foot for a long time. This mod gave me that in spades, and the 'glasspack' sound kind of goes with the 'modern day Led Sled' look.
Here's a little demonstration. Inside the car it's audible but not overbearing. I had to hold off at first to not blast a lady walking by with her dog, and you can't hear it when I turn up the radio but I got another throttle stab in. The exhaust, while 'too redneck' for the crowd that pops wood at the thought of billet anything, has a great burble at cruise, a terrific roar when the loud pedal is stabbed, and is easy to live with on the highway - which is more than many of the folks who've spent hundreds on their exhaust systems have said on the forums.
This post is pretty long as it is, and the intake mods from here out are pretty extensive. So I'm going to split this post into two and deal with all of the mods on the 'other end' of the motor that I've done, bringing the grand total to 45 bucks before taxes for mods that are theoretically good enough to at least equate the F-Body LT1's 285hp rating. If you're from LA and know a dyno owner that'd be cool with my making a run to prove this, I'm all ears, but until then...
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