Stock Exhaust Manifolds

[Racerseks]

Anyone have or know where I can find a pic of the stock L98 exhaust manifolds?

I think I may have shorty headers on mine, and wanna make sure.

If I have the shorties, I'll probably just keep them on. If not, I may go with long tubes.

Thanks!

 

[tigmaned]

the stock manifolds have ugly metal shields to protect the spark plugs. were the shortys would not and look alot nicer. and depending on what year your vette is have the emissions tubes running to heat the cat.

 

[vetteboy86]

I am unaware of any company making shorty headers for the L98 corvette. Regardless, either of the two you have, get a set of long tubes.

 

[Racerseks]

the stock manifolds have ugly metal shields to protect the spark plugs. were the shortys would not and look alot nicer. and depending on what year your vette is have the emissions tubes running to heat the cat.

I have the same year as you.....an '86. It does have the heat shields. If anyone has a pic, I'd appreciate it.

Thanks for the reply!

 

[Racerseks]

I am unaware of any company making shorty headers for the L98 corvette. Regardless, either of the two you have, get a set of long tubes.

Thanks.....maybe down the road I will.

 

[tigmaned]

i was looking at long tube headers today. TPiS has some for $600 paint to coated for $750 both with the front Y-pipe. and i was on summit looking at hooker coated for $529 and front Y-pipe cost of $169. both with emissions since i still have to do that every other year here!
i have seen short tube headers for L98's, but they're about the same thing as the stock ones so i don't under stand them?
if you don't care about emissions, summit racing sells some on ebay for a really good price too.

 

[Racerseks]

i was looking at long tube headers today. TPiS has some for $600 paint to coated for $750 both with the front Y-pipe. and i was on summit looking at hooker coated for $529 and front Y-pipe cost of $169. both with emissions since i still have to do that every other year here!
i have seen short tube headers for L98's, but they're about the same thing as the stock ones so i don't under stand them?
if you don't care about emissions, summit racing sells some on ebay for a really good price too.

Yea, I'll probably consider some of those down the line.....Guessing I have the stock manifolds.....they don't seem as restrictive as I thought they were, so may even just stick with them.....we'll see.

Thanks for the reply!

 

[Mad-Mic]

stock manifold vs TPiS long tube header

here it is again in the car

you can see where the front Y pipe mates up to the shortie header aka manifold.

 

[Mad-Mic]

Yea, I'll probably consider some of those down the line.....Guessing I have the stock manifolds.....they don't seem as restrictive as I thought they were, so may even just stick with them.....we'll see.

Thanks for the reply!

stock manifolds primaries measure 1 1/8" compared to the picture i posted of both the stock manifold and the TPiS long tubed header primary of 1 3/4". that makes a BIG difference and you will definetly notice it! i picked up almost 4 mph from headers only. this means about 40 rwhp.

 

[thirdtimevetteowner]

Racerseks,
Can't help you out w/pics, unfortunately, but I do have a question regarding keeping emissions w/headers, or going w/o the air pump and whatever else can go. Any thoughts on this by anyone? I suppose this subject has been up a time or two, but thought I'd rehash it w/all you C-4 forum members since it was mentioned here already. TIA

Rich K

 

[Racerseks]

stock manifolds primaries measure 1 1/8" compared to the picture i posted of both the stock manifold and the TPiS long tubed header primary of 1 3/4". that makes a BIG difference and you will definetly notice it! i picked up almost 4 mph from headers only. this means about 40 rwhp.

Thanks for the pics and info.....definitely helps out. I bought the car last summer, and haven't had much time to really even check it out!

So.....before I go ordering all the hi-po parts, I thought I'd see what I'm starting off with.

Thanks again!

 

[Mad-Mic]

Thanks for the pics and info.....definitely helps out. I bought the car last summer, and haven't had much time to really even check it out!

So.....before I go ordering all the hi-po parts, I thought I'd see what I'm starting off with.

Thanks again!

np thats what we are here for!

 

[Mad-Mic]

Racerseks,
Can't help you out w/pics, unfortunately, but I do have a question regarding keeping emissions w/headers, or going w/o the air pump and whatever else can go. Any thoughts on this by anyone? I suppose this subject has been up a time or two, but thought I'd rehash it w/all you C-4 forum members since it was mentioned here already. TIA

Rich K

depends where you live. here in maryland we have no visual inspection. as long as you keep it well tuned up and running hot going thru the testing it will pass.

mine did with alot to spare.

 

[tntcorvette]

stock manifolds primaries measure 1 1/8" compared to the picture i posted of both the stock manifold and the TPiS long tubed header primary of 1 3/4". that makes a BIG difference and you will definetly notice it! i picked up almost 4 mph from headers only. this means about 40 rwhp.

40RWHP with a set of headers on a TPI car? No way. The stock manifolds are small but not - 40rwhp small.

 

[ZumZum]

40RWHP with a set of headers on a TPI car? No way. The stock manifolds are small but not - 40rwhp small.

Just replacing the manifolds with headers? No. Put on headers, get rid of the front y and precats, put a hi-flow cat and a good cat-back system or 2 hi-flow cats and a dual exhaust system and you've got 40rwhp. Easy.

The factory L98 exhuast system is the most inefficient of any C4 model.
That, and the TPI intake, but that's a whole other story.

 

[tntcorvette]

Just replacing the manifolds with headers? No. Put on headers, get rid of the front y and precats, put a hi-flow cat and a good cat-back system or 2 hi-flow cats and a dual exhaust system and you've got 40rwhp. Easy.

The factory L98 exhuast system is the most inefficient of any C4 model.
That, and the TPI intake, but that's a whole other story.

I still disagree. The TPI does not make that much power from the factory at high rpm to benefit 40 hp with headers, cat back & even no cat.

 

[Mad-Mic]

40RWHP with a set of headers on a TPI car? No way. The stock manifolds are small but not - 40rwhp small.

for every 1 tenth and or 1 mph equals 10 rwhp. so high 102 mph trap times to high 105 almost 106 mph trap times on a bad day you tell me?

this run was in 1500+ DA from my previous best with out the headers. and for the record all i did was add headers. already had catless front Y pipe i installed before the headers and a gutted cat.

All in all I know what the car will run cooled down and hot. Get me some good DA like I had when I ran the 13.26 which was -1500 DA and sunday was 500+ DA at 60+ degrees and I'd have a strong 12 sec pass. I was hoping to pull a sub 1.80 60' time since my best 60' was last year with a 1.815.

every 1000 less DA is 1 tenth and or 1 mph which equals 10 rwhp also. yeah i didnt pick up much on the ET but i was having troubles launching the car first time out with headers. this day i ran the 105.84 i should of easily ran low 13.0's maybe a 12.9's

Current Mods at the time of this timeslip:
K&N open air box, MAF descreened, TB Bypassed, 160* T-Stat, Accel Super Coil, 12* degree advance timing, TPiS Long Tube Headers, Muffler Eliminators. Stock 1600 rpm stall, 2.59 rear gear on 285/40/17" GoodYear F1 D3's at 18 psi.

here is my dyno sheet. take into account when i run at the track i'm below 160 degrees water temp usually 130-140 range for optimum runs and i dynoed the car at 220+. this equals a +2 tenth loss at the track when i hot lap the car from cold to hot every time. add 20+ rwhp for this. also #8 cylinder, the EGR tubed i fabbed up using just a high temp pressure hose blew out on the first and only pull since i rushed it to the dyno that night. so basically after 3500 rpm there was no cylinder pressure in #8 cylinder resulting in about 15 more rwhp lost. you can see not far into the run there is a sharp spike downwards. thats when the EGR tube blew off. thought it was a header gasket that blown out due to being late at night at my friend Jason Heffners shop. http:www.heffnersperformance.com

so the car should of dynoed around 265-270+ rwhp and about 370 rwtq with the mods listed above which isn't much. thats a HUGE increase no matter what number you look at considering this car like many other L98 vettes dynoed in the high 180 to mid 190 rwhp.

mods i've added but haven't got a true reading from the track is Air Elim Pulley, Crank Pulley, cut back AC Delco Rapidfire plugs gapped at .047, and BFG DR's. went to the track once back in september when it was 90+ degrees with a dead O2 sensor and the best run of the day was on the brakes at 13.54 @ 92 mph.

BTW i've been around racing all my life and i record the DA (Density Altitude) which is a combined reading of the Air Temp, Altitude, Dew Point, and Humidity for each run. I also stage the same and as close to the same water temperature as i can. I'm very Methodical about what i do and i also take the time to know what i done and why it done it.

 

[tntcorvette]

you still will not get 40 rwhp with headers, cat back & no cat or a high flow converter on a l98 car

 

[ZumZum]

you still will not get 40 rwhp with headers, cat back & no cat or a high flow converter on a l98 car

OK, why not?

 

[ZumZum]

OK, I've been reconsidering this whole deal and I think it might have been wishful thinking on my part. Realistically, you would probably only see a max of 27-30 hp at the rear wheels. And that's inlcuding such items as a K&N air filter and cut air lid. Plus the whole low restriction exhaust to go with the LT headers.

My bad.