--- I just want someone to tell it to me straight out - am I wasting money by putting aftermarket headers on a bone stock LT1? ---------
- Bob

Bob,
Bob here so you can trust me. Straight out the answer is "No". The old saw is start the mods journey starting at the back and working forward. The boxstock motor ain't the issue as much as the craptastic but 'customer quiet' restrictive original exhaust. You're attending that soon with the new catback though. A pesky bad bad but true fact is your car will actually go faster with just a 2 1/4" new setup all the way up to ~350hp. At the wheels. But it'll look and sound faster with a 2 1/2" so forget I said anything.

Of course you need better intake air flow we all know. But it's been proven (though not as pretty or expensive) to just do the Homeplate and firstbase deletes using a sewer pipe, along with swiss-cheesing the filter box. And please no K&N or the other brand fancy red or blue cartridge filter (that you can't see anyway). They don't measure up for as effective particulate contamination filtering, or even remain better flowing after just a short while after installation as a good quality WIX/NAPA.

There dwindling sources for headers for our aging platform. Of all the major players the only ones I've heard were 150% plop-n-drop are Tri-Y. I can attest that's the case with mine. Do a WTB post and someone might part with theirs, or, you might get another brand that's been 'pre-tweaked' to fit by a previous owner.

The only real waste is NOT getting a tune to get improvements on the ground after doing as much add-ons as you can afford beforehand. best luck.

 

Of course you need better intake air flow we all know. But it's been proven (though not as pretty or expensive) to just do the Homeplate and firstbase deletes using a sewer pipe, along with swiss-cheesing the filter box. And please no K&N or the other brand fancy red or blue cartridge filter (that you can't see anyway). They don't measure up for as effective particulate contamination filtering, or even remain better flowing after just a short while after installation as a good quality WIX/NAPA.

I was meaning to track down an old post I remembered finding here some several years ago, a list of mods recommended to start with. I have owned this car (second owner) since around 40k and have only maintained it. The exhaust (and subsequent audio upgrades coming) are the only things which will be done on the vehicle. I need some guidance in direction, I'd love to do a home plate/first base delete, CAI, and anything else within reasonable means to sort of strike a new heart string for the ole girl. She's stuck with me for life and I think it's time to do a little pampering. She's coming up on her Antique plates down here in FL and she's earned it.

- Bob

 

Marky, wow all the oldster handles in the link in the first post !

 

1" wood spade bit and patterned holes drilled to increase free air opening over the original little oval inlet. I recall simply centering the holes inside the square molding grid. I also recall looking for areas where rain or splashes might get in but decided that not to be a real concern. I have a habit of inspecting the filter ~few months to make sure nothing liquid or rodent-like got in.

 

Thanks a ton! I'l gonna go through with the Swiss cheesing this weekend, I may grab a K&N filter for her while I'm at it. I'll do the home plate delete once my "puck" arrives.

- Bob

 

Just use any hockey puck. I found one on the road and gave it to my son. Then stole it back when I did the mod. And you're getting that K&N why? "I've done my research!" Actually, more than one published review using actual measurements has the filters I listed as performing better than that one.

 

If for whatever reason you don't like the idea of a hockey puck …
Many years ago (lost to the Great Data Misplacement), someone here used glass jar lid that just happened to fit perfectly.

K&N is not worth the inferior filtration.

 

The contributions are all spot on.
I just wanted to add that I was happy beyond belief when I first put on (only) a 2-1/2” cat back exhaust. It was my first mod, and while I think it was worth zero horsepower, it made the car perfect. Leave the exhaust manifolds and catalytic converters alone. The car becomes muscular and satisfying. Completely reliable and cool.
Just be careful, because if that mod bug bites you like it bit me; you could become as poor as as I seem to stay.

PS I had custom bent 2-1/2 pipes, dynomax ultra flo mufflers, and no resonators.

 

I run a stock exhaust with full size turbo mufflers and a swiss cheese air box(stock filter) and hockey puck intake elbow.Car is stock other wise.It sounds good runs great and is fun to drive.If it helps Bob, here's a how to picture I drew up in 1997 of how I did the drilled air box mod.
Good luck with yours! Jim

 

Here's the picture

 

There is no downgrading. The original exhaust is 2 1/4, but the terrible crimped bends (some measured even less than 2", severe flattening to clear areas as the crossmember, along with notably restrictive mufflers resulted in a system that's overdue to be replaced right off the showroom floor. To promote exhaust velocity through the system, even to the point that it acts to suck intake charge better into sequential cylinders, the goal is scavenging which tests consistently show is best accomplished keeping hot gases moving at a higher speed through a correctly designed tube. Borla catback has been around since soon after the Impala SS hit the street. But funny that a guy in our local club who grunted past the $1,200 cost and installed it over 20 years ago did NOT get the positive reaction he thought he would from many members. The consensus was that it was "too damn quiet to be any good." Hahaha For the LT-'s cfms x revs, tests show a 2 1/4" caps out at ~350.

 

There is no downgrading.

I should have said "downsizing".

For the LT-'s cfms x revs, tests show a 2 1/4" caps out at ~350

I feel like this isn't as simple as RWHP and exhaust pipe size. How long is the pipe? How is the pipe shaped? Does the car have cats? Which headers? Which mufflers? I'm assuming that you are only speaking about N/A applications.

It seems strange that after all these years we don't have any side by side data on this. Would be interesting to take a mildly modded car and dyno it numerous times using different exhaust setups.

 

Thank you for all of the replies, I will stick with an OEM stock-style air filter per your recommendations, The exhaust goes on early this week, I will take that, the audio upgrades (CT Sounds front/rear speaker replacement, Pioneer headset, self powered Rockford Fosgate Punch 300-12 Sub/Amp combo) the Home plate/First base delete and air box mods and run for a bit. I admittedly felt the bug creeping on, hence the header questions. I'll report back after the aforementioned is done. Thank you all once again for being examples of why this community is home to some really helpful, great people!

- Bob

 

If you delete homeplate and don't want to use a hockey puck, you can get a rubber elbow from Camaro/Firebird. GM pn 25147210 or Dorman 696-077. It has an oval fitting on the bottom for a small vertical resonator (same noise reduction idea as home plate, just a different shape). Just make sure you get one that doesn't have the oval already cut open. You can trim off the excess vertical part.

 

Many ,if not most have settled on 2.5" systems... Three inch is overkill for the vast majority. Plus ,one does run into clearance issues around rear-end housing especially.

 

I also settled on 2.5" catback Spintech Pro Street 9000's

 

Bone stock EVERYTHING?
Shortie headers, probably not worth it. Long tube headers without catalytic converters, full 2.5” exhaust like you’re getting, in addition to some intake modification and a pcm tune will make a bit more power and sound even better IMO, but “worth it” to every individual varies wildly.

For a nice stockish cruiser, nah.

For someone like me, flogging the crap out of the car every time it’s out of the garage, and spending a fair sum of money on a large, aging sedan, sure! 😁

 

Bone stock EVERYTHING?
Shortie headers, probably not worth it. Long tube headers without catalytic converters, full 2.5” exhaust like you’re getting, in addition to some intake modification and a pcm tune will make a bit more power and sound even better IMO, but “worth it” to every individual varies wildly.

For a nice stockish cruiser, nah.

For someone like me, flogging the crap out of the car every time it’s out of the garage, and spending a fair sum of money on a large, aging sedan, sure! 😁

I will be doing the home plate/first base delete along with the swiss cheese intake mod, longtube headers maybe somewhere in the distant future, going to start researching tunes soon - seems intimidating though..

- Bob

 

Now I see where you were coming from.

Agreed.

 

OP

My $.02...and I am an original owner who has jumped deep into the mod pool

DONT swiss cheese the stock air box. That only lets hot engine compartment air in. If you want a CIA get a K&N F.I.P.K system

ANY motor will benefit from headers. The ? becomes is the 10 hp gain on a stock motor worth the $

Performance mods work better when they are combined which is a domino effect that cost $ but does increase HP. Example. PCM tune, CAI, headers, 2 1/2" cat back, 2200-2400 stall TC, Transgo shift kit, 3:42 or 3:73 gears.

2 1/2" exhaust will give some HP but also give up some low end TQ...BUT, if you are doing a "tune" than the 2 1/2" will benefit.

Ed Wright (Fastchp) may still be doing mail order tunes and is arguably the Godfather of GM OBD1-2 tuning. moehorsepower (Moe) has a good reputation but I have only used Ed.

Learning to self tune will cost WAY more than paying someone who knows WTF to do. Its not about turning everything up to "11" (Spinal Tap)

To get the most out of a mail order tune you would want to put in a 160 Tstat so more timing and lower fan temp "on" will allow more fueling thus more power

If you don't see a lot of long Fwy driving than 3:73 gears will really wake up the car but if a lot of Hwy go 3:42 IMHO

Home base delete....well its a cosmetic mod but with it removed the engine looks like crap so some form of "dress kit" would be suggested. The LT1 Corvette one, to me, looks the most appropriate but there are aftermarket ones you can get. If you do home base delete just get the F-body elbow posted earlier

 

I opened the end of the filter box next to inner fender. Pretty easy...

 

The whole stage 1/2/3 thing is more of an import phenomenon, particularly in factory boosted applications where massive power gains can be had with basic mods like tuning, downpipes, etc.

It would be easy for us to identify "stages" of b-body modding, but we just don't use that terminology.

Side note: I thought headers were supposed to be worth like 20 hp or more on our cars due to how restrictive our stock manifolds are. Maybe I'm thinking headers + exhaust together?

 

Side note: I thought headers were supposed to be worth like 20 hp or more on our cars due to how restrictive our stock manifolds are. Maybe I'm thinking headers + exhaust together?

I don't measure HP but a set of cheap 1 5/8" mid length ebay headers and dual 2.5 w/h pipe gave me .2 in the 1/4 mile. DIY tuning with wbo2 netted another tenth and I am a noob tuner (is possible a 'pro' would have gotten better results.) I also saw no ET improvement on premium fuel even though I could run up to 7 degrees more advance w/o knock...

 

Hi, nice to see good info in here for the new guy.
I tried the sewer pipe, with a HP and 1base delete. Throttle response felt the best with my butt dyno.
But i settled on Silicone coupler on the TB and MAF and Air filter cuz i like how i looked.

Since dynomax stopped making both OTA pipes in 2.5 inch i am glad i went 2.5 inch cuz exhaust shop pipes have crappy bends so it flows like a real nice 2.25 inchi bet. Plus the Spntech super pro streets are crazy loud like i like it.

I suppose if i had the money i would start 2.5 inch and after muffs goto 2.25 inch as the air cools down and flows slower, also cuz Walker still makes the OTA pipes in 2.25 inch i think. Dynomax is just performance division of Walker, BTW.

-ALF out....

 

While the 2 1/2" OTA DynoMax pipe is often "not available"...I have purchased them at Autozone separately. My guess is they run batches of them similar to when Gates runs batches of the long not available PS reservoir to pump hose

 

The further from the source (manifolds/headers) pipes are. The less difference that diameter makes. Obviously a 2.25" mandrel bent tail pipe is dramatically better than a 2" crimp bent tail pipe. Regardless if resonators are used.

 

My experience with headers is from friends that have replaced factory cast exhaust manifolds with headers. All that installed big tube 4-in 1 headers lost bottom end power and very little, if any top end. On the other hand, the tri-y headers did make more power on stock engines, even before adding aftermarket exhaust. According to one person, adding low flow cats was the single biggest difference, then a mandrel bent cat back system helped more. My Impala SS has headers and stock cat back exhaust, which is worthless without the aftermarket exhaust. You will tell a difference with a tri-y headers, high flow cats, and 2-1/2 mandrel bent exhaust system. The stock exhaust has a lot of restriction because of restricted bends that reduce 2-1/4 diameter down to 2 inch. An LT1 needs more exhaust than 2 inches. There will be a difference with a cold air intake and free flowing exhaust. From people I know, tri-y headers, high flow cats, and mandrel bent exhaust system has made an increase in power on a stock engine. What has not is big tube shorty headers and stock exhaust system. The great thing about improving the intake and exhaust system is, you have that in place if any other mods are in the future. I say, have a go at it, and have fun doing it!

 

Went back to the stock air box, "swiss cheesed", and lost zero performance at the track. Run low 12's at 108 -111 all day long depending on track and weather. Zero difference with ET & MPH swapping back to the stock box. Cut to fit a $5 plastic trash can from Walmart for a DIY heat shield. Plug for the stock intake elbow is the bottom of an old Freon can cut down to fit. TriYs are a great header for a stock LT1 BUT the cost to performance ratio is very high. Better off with gears, TC and tune. If you go with heads & cam, and/or stroker, that would be the perfect time to go with headers.

 

Lately I have been feeling like a modified stock airbox may be about as good as it gets. I'm thinking intakes for our cars may rank like this:

1. True ram air setups
2. Modified stock box, and every other "cold air intake" on the market
3. "Hot air intakes" without a heat shield

I'm about to experiment with a filter down by the bottom of the radiator, but I won't have any numerical data on it.

 

at the moment I wouldn't do any modifications to emitions EPA is raiding all manufactures of after market emitionss fining them getting costumer list and going after anyone who modify there machines its all over the internet and youtube there is a petition SEMA and others are trying to pass called the RPM act.

 

Cite source(s) for this info. Hopefully established credible sources ,and not trade group propaganda designed to attract donations/hysteria.....

 

Hi, i'm cool with rehashing stuff, part of the fun. Didn't want to muck up the OP's thread any more.
Maybe start a new thread and we can get another discussion going on what you are wanting to talk about.
Later,
-ALF out....

 

Ah yes, I love the smell of an ancient circular argument in the mornin'. Having not learned from the past is assurance of it repeating.
Evil minds think alike as I was also hoping to get back to more of the thread title related content. Those old threads do serve to refresh the decade's-old info, discussion, argument(s) and cognitive dissonance surrounding CAIes, - and cone filters. All scientific SOTP aside, I liken the whole topic as more STTE (Sparkle To The Eye). And cone filters are in plain fact much prettier than another random car battery looking box stuck under the hood. However, results of actual measuring instruments show that any miniscule elevated underhood temps at idle are quickly dissipated back to ambient temps soon after the car is moving again. With or without a 'heatshield'. That's not to say I didn't buy two SSRIes when they first came out. Sure they were $700 each, but they were pretty. They still are. But I'm sure not going to argue the results of 3rd party measured testing results showing performance of a good cartridge filter and simple DIY improved intake flow v. aftermarket setups costing $$$hundreds more. And we're moving along.