hey guys. i'm trying to find a set of headers for my '81 that are smog legal and has the clearence i need for how low my car is. i figure the L98 headers have to be way better than the crapazz headers that came on my car and the cheapy summit headers i've been using for the last few years. i'm not looking for the absolute best headers out there (hence, the factory header question) but either a good set of factory or aftermarket smog legal headers that will support about 250-300hp and give me the clearence i need. what is your opinion of the factory headers? what aftermarket 'shorty' headers are out there?
what about LT1 headers? are they actually different from the L98 and earlier design?
due to ground clearence issues, length is critical

 

If you look through summit, there are plenty. Hooker SuperComp 2151s and 2149s are the ones often recommended for my L98 ('91).. I know they have uncoated shortys for right around 300ish... (+/- 50, don't remember). They also sell some LT headers for 550ish, ceramic coated and all. Nice set of headers. Look around. : )

-Joe

 

The only real advantage to the shorties is their weight savings.

LPE uses shorties because they are 50 state legal...

There are no long tubes that are 50 state, but many are 49 state. The biggest problem is the cat position - and CA gets **** about cat position.

LTs are also going to be slung real low...

do you have true duals?

I would do this - considering you are in NV, you can do this - ditch the entire exhaust. Get some headers and bullet cats, then put in an X-pipe and duals all the way back. You will pick up 50hp over the factory exhaust, and still be smog legal! Infact, using the new bullet cats, you will be even MORE smog legal!

 

The comps have to big of primaries for his app 1 3/4. however there are a few 1 5/8 out there hedman and such

 

plus hedman has a smog legal setup... i forget the model number offhand though

 

Bogus,

Fifty horse with long tubes? Really? Does the X-pipe factor into that or is it primarily the headers bumping up the HP? I haven't done LTs yet, but have plans to and if fifty horse is a reality, i'll be concentrating on getting them sooner!

:

 

on an L98, i'd definitely think you could pull 50HP from a LT/dual exhaust setup. If you use the right LT's, and a good true dual setup...

on an lt1/4 its prolly less...

 

thanks, guys. i'll start looking through summit or jegs for a set of L98 shorties. i would think those should do just fine.
only concern i have is i still have mechanical clutch linkage that would interfere if the #7 tube goes straight down. you c4 guys don't need to worry about it with the hydraulic clutch set up. any thoughts on that for you guys that have already replaced your stock system with hedman, hooker, etc.? does the stock manifold come straight down like that?

 

Here are your Hedman numbers: 68447 and 66447 I believe the first is coated and 616.95 , the other 304.95 and uncoated, thru Hedman. Their cat# is 13910 These are 1 5/8 primaries w/smog tubes for L98

 

Jloshotz, I think maybe 40chp over bone stock exhaust might be closer even with true 2 1/2" duals and bullet cats.

clutchdust, it looks like Summit has headers for late C3s by both Headman & Hooker.

 

jim is right, 40CHP is max.......i got 25CHP with headers,highflowcat, and catback.

 

My frame of reference is for the 1981, using a stock monolith cat.

Adding 50hp doing that would be about right. You see, those old school cats were sooooo ugly... bullet cats, LTs and true duals will do it to it!

Hell, might even be more.

 

here are some pics to consider. not the best but will give you an idea of the clearances on LT headers.

first is stock shorties which are 1 1/8" primaries. TPiS headers i have are 1 3/4" primaries



this is how tight the exhaust sits the the frame



Drivers side clearance. no the best pic but judge the clearance from the oil filter



passanger side. you can judge the clearance from the frame rail that the lift arm is on.



the headers are actually pretty up tight close to the frame rails. your only talking 1-2" at most below the frame rails.

hope these help!

 

with my basic mods:
K&N open air box, MAF descreened, TB Bypassed, 160* T-Stat, Accel Super Coil, 12* degree advance timing, plugs gapped at .047 Indexed, TPiS Long Tube Headers, with straight dumps off the rear Y pipe. Hayden Tranny cooler. Stock 1600 rpm stall, 2.59 rear gear on 275/40/17" BF Goodrich Drag Radials.

these were my mods at the time i did a dyno pull after i installed headers. i did not have dyno numbers to know what the car did in bone stock form but going at 240 chp and 340 ctq the car made 245 rwhp and 350 rwtq @ 220+ water temp while blowing the EGR hookup on #8 cylinder this left a good 20+ hp on the table along with another 20+ rwtq if the car was at race temps and NOT city temps. going by a 20% loss due to drivetrain the car made 49 More cHP and 70 More cTQ over factory specs.

so IMO L98 or SB1 blocked cars benefit ALOT from headers especially Long Tubes i picked up 3+ mph with Long Tube headers alone.

this would explain my 1.2 second on average drop in ET with the extra TQ and HP along with traction and alot of tuning

*Note* Not all Cars will see these kinds of numbers. i would be willing to bet my car is on the other end of the bell curve due to alot of old school tuning. ie plug gapping, indexing, playing with timing, and air pressures in the tires for maximum grip. this is just a generalization about *What* your car *Could* see with the same basic mods.

Dyno runs have shown on LT1 and LS1 cars around only a 20-25 at most rwhp gain with long tube headers only.

 

i've seen those headers listed and talked with many other c3 owners who have them or a variation of them. the problem i have with them is they are all long tube and they are all G.M. generics, so the ground clearance issue comes into play. novas and chevelles don't need nearly the ground clearance that the c3 does, even when they're slammed. as it is, those hookers become the lowest point of a c3 by close to 2". not so bad for a car still running the stock ground clearance of 6.5", but mine is less than 5" now.
alot of your HP estimates are probably very close, for a stock system. i'm currently cat-less true duals and when i switched, i would say it was worth about 40hp. my only problem is, it's not smog legal. so if i move someplace where smog becomes an issue, i'm going to have a major problem.
i think i'll check out those TPIS pipes. thanks