Headers, need to move fast

[Trance_LT4]

I am about to buy a set of full length headers off an 85 corvette for my 96 LT4 vette. I've been told they should fit the engine no problem. I have a few concerns I need to have addressed by folks who know.

#1 I don't have EGR, and I'm sure that these headers aren't equipped for EGR, so no problem there, right?

#2 Is there anything that my OBD2 computer is going to flip over?
I plan on running no cats or gutted cats, and will be using O2 sims. Can anyone think of anything else? I'm getting them real cheap, so I don't want to have to do a whole lot of extra mods to get them to work.

#3 I'll be using a completely different exhaust setup, more than likely utilizing most of an 84-91 exhaust system. Will that bolt in the same way as my 96 system?

Here is the pic of the headers (I will obviously be having them coated)

 

[Ken]

Will the headers that were made for an L-98 fit an LT-4?

_ken

 

[Trance_LT4]

The guys at TPiS said they should fit no problem. The headers are basically the same, the only difference being how you connect the exhaust afterwards. Since I'm going to piece together/fabricate everything after the headers, I don't think it should be a problem. Its only like 60 bucks I'm spending on the headers, but 1 dollar wasted is still wasted, so I just want to be sure I'm not overlooking anything.

 

[Ken]

:cool

 

[Burnnrubber]

Hello,
I just purchased a new set of Lingenfelter Ceramic Coated L98 headers, for my 1995 LT4 conversion. I spoke with Lingenfelter's shop prior to buying them on EBay. I was told they will fit just fine, the differences are in how they hook into the the older style center mounted catalytic convertor. The ones I purchased were 1-5/8" Dia. primarys. Most of the LT series headers are 1-3/4" Dia.
I went out & measured the stock Exhaust manifold & the largest cross section I could find was only 1-1/2" I've also read some info that calculates primary Dia's. They say 1-5/8 primarys should be good up to 400 horsepower & above that you should go to 1-3/4"
Also the smaller primary's help keep the exhaust gas velocity's up which increases the scavenging effect & produces more low & mid-range torque. I have the OBD-1 system & plan on running all (3) heated 02 sensors. I think you will need the simulator on the rears 02 sensor positions of the OBD-2 system to keep the check engine light off.

 

[Trance_LT4]

I forsee a small problem now. My stock exhaust manifolds have a AIR system, that connects to the center top of the manifold, and these headers (I think they are hooker long tubes) do not have AIR hookups. Any ideas on how to disable this system, and will it trip any error codes?

 

[-=Jeff=-]

Those don't look like hooker headers. Hookers have a solid flange at the end.

Anyway as for exhaust.. you can modify you cat back to use with headers.. there will be no cats though.

here are a couple of pictures of my Hooker headers with an LT4 cat back

you can see the passenger side where you need to add a pipe in the close end of this picture

 

[-=Jeff=-]

here is the driver side tubing that will need to be cut

 

[Trance_LT4]

You're right, those do have a sliding flange at the end. Maybe Mr. Gasket? I'm going to use a hooker y-pipe for an 86-91 vette, then use a random cat with a slip fit on one end, and a 3 bolt flange on the other, with a yet to be decided on 86-91 rear y pipe, going to some LT1 style targa mufflers for an 86-91 out of Mid America. All the diameters numbers seem to match, and I hope it all bolts in well.

 

[-=Jeff=-]

You're right, those do have a sliding flange at the end. Maybe Mr. Gasket? I'm going to use a hooker y-pipe for an 86-91 vette, then use a random cat with a slip fit on one end, and a 3 bolt flange on the other, with a yet to be decided on 86-91 rear y pipe, going to some LT1 style targa mufflers for an 86-91 out of Mid America. All the diameters numbers seem to match, and I hope it all bolts in well.

I would not do that..

If you get those headers.. get a pair of Random 3" Bullet cats.. one on each side of the 6spd. then either mate it to your stock cat back or aftermarket LT1/4 Cat back. your stock system is 2.75" dia.

Most 91 earlier systems were 2.25" and only a select few make 2.5 or3" rear catbacks. I honestly think if you do what you are planning you will not gain much, if anything.

The stock LT1/4 Catback is nice.. believe it or not the Resonator on that system is 2 DUAL pipes through it. You stock mufflers MAY be a restriction but those can be replaced.

here is a picture (not very good) of my random cat next to the trans.. this was my set-up last year.. Hooker headers.. dual 2.5" cats and a Flowmaster 2.5" LT1/4 Cat back

 

[69MyWay]

This will work, but you will have some mods. You should have two O2 sensors in that LT4, so an extra O2 bung will need to be welded into the other header. You do not have to run the AIR tube. However, if you want to hook it up, simply have an welding shop cut the header and have the stock flange welded in. Then test fit, then send them out to be coated.

I have no opinion for you on the CAT back portion. I would really respect Jeff's opinion on the CAT back portion. He really knows his stuff.

 

[Trance_LT4]

thanks Jeff

Good advice, I took a look at some 2.25 size stuff today compared to my 2.75. High end power is what I want to increase, and that will definatley hurt. How difficult was it to squeeze those bullit cats into the stock style exhaust? My problem is that my fabrication/cutting/welding abilities are limited. I can install the headers no problem, but after that........and I don't want to pay someone else 300-400 extra to do something I can do myself. The problem is how I get the car to a competent muffler man once I've installed the headers.

Perhaps I could just drop the whole exhaust, install the headers and the O2 sims, then drive to the closest muffler shop, avoiding any John Q laws......or bite the bullet and pay the 80 bucks or so to have it towed to a nearby shop.

Are your cats easily removed for replacement? I'm wanting to be able to take off the cats and put in hollow ones and be able to switch back and forth.

 

[69MyWay]

I always look forward to the early saturday morning after having installed a set of headers, easing the car into the street, cranking it up, and easing onto the main road, then feeling like a Nascar driver for the next 6 miles or so to the muffler shop.

I suppose you could get a ticket, but no doubt, you are on your way to fix it. Just don't hot dog for the sake of hot dogging. I remember after I put the V8 in my S10, I drove right past a cop with open headers on my way to the muffler shop slow and easy. The S10 was still painted white, and looked very normal and mild. I could see the cop straining to look around in traffic to figure out where the sound was coming from! Same thing with the V8 Fiero. Nobody suspected all that noise was coming from that little door stopper.

With all the fabrication I on my own, I leave the exhaust welding to the pros. My local shop is fast and friendly with low low prices. I spent $80 having the collectors, O2 bung, and the entire center exhaust bent and mounted to the Flowmasters on the 90 model after I installed the Headman headers.

 

[-=Jeff=-]

Re: thanks Jeff

Are your cats easily removed for replacement? I'm wanting to be able to take off the cats and put in hollow ones and be able to switch back and forth.

Not really, I don't have cats anymore. I changed the exhaust this year and ditched the cats

 

[sothpaw]

TranceLT4,

I saw an earlier post from you where you
were telling someone how much hp you got
from your flowmaster cat-back exhaust system for
$600.

How much more does a good set of headers buy
you?

--I am strongly considering a set of headers
but I don't understand all the mods you
guys are discussing as necessary. I'm not
inclined to do anything myself. I have the
stock exhaust and don't have the $$$ to do
headers plus exhaust

Any recommendations for a good set?
What should I buy and how much labor
will have to pay for?

 

[Trance_LT4]

Headers (full length) are normally costing from 400-800 for C4 corvettes like yours and mine. They make a definate improvement in power, as for a hard and fast number, there isn't one, but I wouldn't be suprised if I gained 20-30 hp at the rear wheels over my stock manifolds.

Shortie headers (the kind they sell that will fit your stock exhaust system with no mods) are just performance manifolds, and you won't really see any gain from them, they just look better than that brown cast iron manifold.

Doing a header swap is a very simple job in and of itself. You can save yourself 300-500 bucks labor from a mechanic if you can find a friend wit some experiance to help, or read up a little and do it by yourself.

Most full length header jobs require a little cutting/welding on our vettes, but paying 80 bucks for a tow over to a muffler shop to finish the job after you have the headers installed is still saving money over giving the whole job to someone else.

 

[-=Jeff=-]

TranceLT4,

I saw an earlier post from you where you
were telling someone how much hp you got
from your flowmaster cat-back exhaust system for
$600.

How much more does a good set of headers buy
you?

--I am strongly considering a set of headers
but I don't understand all the mods you
guys are discussing as necessary. I'm not
inclined to do anything myself. I have the
stock exhaust and don't have the $$$ to do
headers plus exhaust

Any recommendations for a good set?
What should I buy and how much labor
will have to pay for?

Do you want to keep cats? if you have a 6spd, you can buy a set of headers from TPIS or Exotic Muscle that are coated and have them installed and get some Bullet cats to connect after the headers and mate to your stock cat back. You can also Get Hooker headers from Summit Racing coated or non coated.

Granted my vette is an L98 BUT, I am using a LT4 STOCK catback. I have Hooker headers PN 2151 (no AIR tubes) and have them connected Directly to the stock LT4 cat back. The Stock exhaust found on LT1/4 cars is quite good. I don't think it is necessary to replace the Stock exhaust as is flow well. The mufflers may be a restriction. If I decide that the mufflers are not helpign but hurting, I will buy the Magnaflow muffler set and keep the stock resonator.

Hope this helps
-=Jeff=-

 

[sothpaw]

Guys,

So, for my LT1 6spd C4,
you recommend TPIS or
Exotic Muscle full-length
headers (at cost $400-800)?
Jeff, it sounds like Hooker headers
will do the same trick for the LT1?
And coated headers are better why?

--My co-worker recommends Sanderson
headers, but he's into 30's muscle
cars.

--Should I pick the Dia. assuming that
my car is under 400 hp as discussed above(which it certainly is now)?

--I want to keep the car streetable
so I need cats; will replacing the
cats on the LT-1 increase hp and pass
emissions? Cost?

--If I buy the TPIS, for example, are there
any other parts I need?

--TranceLT4, you live relatively close to me,
what shop are you going to use for the muffler
work?

Thanks so much!!!!!!!!!!!!!!!!!!!!!!!!

 

[Trance_LT4]

I'm just going to use Midas for the work if I find that I can't fabricate the area between my header collector and my resonator. I'm using a flowmaster cat back, but its the same as stock dimension-wise. You sound like you need a good performance shop though, as you will be having the whole job done there, right? Check out the phone book for "automotive racing and performance products" or something close to that for speed-shops in your area. I go to Crofton, which is about an hour away from you. I'm sure you have one closer.

As for your questions

#1 Lots of companies make headers, but very few make em that will fit an 84-96 corvettes body. Hooker, TPiS, EXotic Muscle, and Lingenfelter are the ones I know of. Uncoated Hooker headers are 400, the coated ones are 600 (I think), other brands vary.

#2 I'd go with either 1 5/8 or 1 3/4......you won't see much diff between the two on your LT1, they both make good power over the stock manifolds

#3 Replacing the stock cats with high flow "random technology" cats will help, keep you streetable, and you'll still pass that annoying MD state emissions inspection. The cats pric depends on the size you get. I would suggest the bullet series, since they are only 8 inches long (I think). They cost about $330/pair

#4 You will need : a) the headers b) exhaust gaskets c) clamps (unless they weld it) d) the cats e) a few feet of exhaust tubing, size depending on what headers/cats you get......you might only need a foot worth, but a little left over never hurt.

If you get headers with a flange (bolt-up) ends on them, you will need a collector and gaskets to bolt to the headers and slip over the end of the cat to clamp or weld. If you get headers with a slip-fit end to them you can put the cats right on the end. However, I hear placing the cats further back helps because the air is smoother further away from the collector.

 

[-=Jeff=-]

Coating of the Header helps keep the heat where it should be.. in the Headers.

After driving a car with Ceramic coated headers.. you can touch the headers after about 30-40min.. The coating also help keep the headers in good shape