nicksL98

iTrader: (6)

who has them or would be willing to do a flow bench test on them? I see most people putting headers on their cars that dont really need it IMO, so i'd like to find out the flow capacities of 85-6 305TPI H.O. manifolds, 87-92 L98 Manifolds, and the 90-92 TBI/ Base TPI manifolds.

My opinion is substantiated after i told an SD L98 Camaro owner he would see NO gains whatsoever from full SLP headers and catback, sure enough over $1000 later and 2 trips to the track it ran the same or .05 sec slower than it did with stock manifolds and Y-pipe(stock egine).

Can anyone help me out?

onebadwagon

what are you talking about, that really dont need it? any engine should benefit from headers.

the more air in, the more air out, the more power made. simple.


adam

Blown87

iTrader: (1)

You won't benefit at all if the original set up can handle the flow that the engine is putting out. I agree, on a stock set up, headers will not give any more performance. Once you have performed mods that will increase engine output, exhaust upgrades will produce benefits.

Ricktpi

Headers aren't just about flow, the scavaging effect of seperating each port into a tuned primary is the main benefit, increased flow is the by product. It's a proven fact, a stone stock 305 TBI will benefit from headers, mods just make it more important.

Blown87

iTrader: (1)

That is a good point.

nicksL98

iTrader: (6)

Blown87 is understanding what im getting at and RickTPI brings up some good points. A stone stock TBI would benifit the same with L98 manifolds as it would with headers. But i am still loking for flow numbers, not why headers are better. I have seen a 91 Z28 L98 run 13.50's with the stock manifolds cats, ect and aftermarket catback- putting headers on that car made NO improvement whatsoever(including Tuning for them).
I would think TBI manifolds would flow the worst, the 85-6 tpi untis in the middle and the 87-92 L98 manifolds would flow the best, im just wondering how much better. I do not want to put headers on any of my cars so if i can retain the manifolds and make a high flow y-pipe/dual cat setup and be free and clear( i have a Huth bender so, yes i can make my own) i'd love it.
If i am not able to get flow numbers either way, you guys will still see my setups when finished including before and after track results.

Ed Maher

JUST swapping to L98 manifolds and dual cats i went from

2.157 - 2.233
6.282 - 6.297
9.655 - 9.624
72.94 - 74.46
12.487 - 12.468
15.052 - 14.889
90.58 - 93.18

1bdbrd

iTrader: (1)

why are you going to waste time doing the job to put stock manifolds from a different motor on? thats just retarded unless you for some strange reason MUST keep manifolds. you WILL see a gain with headers if installed, and driven correctly in good weather. i am willing to bet that 91 z28 gain a good bit of mph in the trap speed but maybe not. just like i added an ASP underdrive pulley and a homemade 3inch CAI to my 91 last week along with a new TPS.i improved my best from a 14.54 to a 14.53. that whole reason was because of weather. i had perfect weather when i ran the 14.54 but last week was humid as hell. which means i DID pick up a couple hp but the weather wasnt there to show it.

get a set of headers dude. trust me. race cars run them for a reason. i dont know about you but at the local car show tonight, i didnt see one strip car with stock manifolds on it....

nicksL98

iTrader: (6)

who said i was swapping manifolds? im looking for FLOW NUMBERS NOT WHY EVERYONE THINKS HEADERS ARE BETTER! good ***. the 91 Z28 DID NOT HAVE ANY IMPROVEMENT OVER THE STOCK SETUP! GOT IT?! I was there! Im not you average dumbassTBIer that posts on tgo who thinking he can make his L03 run 12's.

i KNOW headers are required on GOOD engines, my chevelle wouldnt be in the 11's without them. BUT why waste my time and money on installing headers on a 14 sec car if i can use my existing manifolds, make up a dual 2 1/4 or 2 1/2" y-pipe with dual cats and put a good catback on it and be right next to you sorry souls who blew $400+ on headers and a catback?

brodyscamaro

Why? Because most do it right and do it once. I guess you don't. And for the record I don't care how many tenths the headers/exhaust knocked off the L98 car, whats the MPH gain?

nicksL98

iTrader: (6)

For the record - Zero, nada, nothing. if you want to, ask him for yourself, ThrdGenZ28 from New Jersey ( blue 92 z28) Hes a great guy but i told him headers would not give him any perfomance increase and i was completely correct.

Also, id be willing to put any of my cars up against your piece for any catagory, workmanship , performance, appearance - IF you want to get into the argument about doing things right the first time. bring your car up to ohio if you want to do this in person.

Edit: I just saw your pics of your car, you'd lose.

Mark A Shields

OK, just for a second let's assume stock manifolds flow enough for a near stock motor , have you looked at the stock y pipe??? my G0D, it's a joke,talk about restriction.

Put on a set of headers and a nice y pipe and you'll see improvement.

Marc 85Z28

iTrader: (3)

nickL98 - You're crazy. Just because 1 car did not see an improvement with the headers does not mean it can't help. I think he's got tuning issues - regardless of whether or not he "tuned" it already.

Personally I saw a full .9 gain with headers and 3" exhaust - on a stock 155HP 305.

And on another note, I watched a 91Z28 with nothing other than longtubes and dual 2.25" exhaust go from 14.3 to 13.7.

nicksL98

iTrader: (6)

Most of you have added nothing worthwhile to this topic - i dont care if you think headers on a stock engine are awesome- truly i don't. I asked for manifold flow numbers, if you dont have any insight to them the get the hell out.

thanks to Ed , blown and ricktpi

25THRSS

All I have to say is you will see a huge gain with any headers over any stock manifold on even the lowest hp third gens. I read a buildup of a 145 hp LG4 where they added long tube headers and mufflers to it and it dyneod 197 fwhp afterwards. You are crazy if you think the stock manifolds can flow enough for even a stock engine, LG4, L03, L98, whatever it be, it WILL benefit from headers. Save yourself the trouble and screw the manifolds and get some headers.

Marc 85Z28

iTrader: (3)

Did you honestly expect to come on here saying headers are worthless on stock engines and not expect replies?

Nobody flows street intake manifolds, much less stock TPI units. I doubt you'll ever see the numbers.

Better yet, anyone got flow numbers of stock exhaust manifolds vs headers

25THRSS

Also, as Ricktpi stated, it's not all about flow, scavenging has a lot to do with that and once again headers will not only outflow manifolds they will do a much better job of scavenging the exhaust pulses as well.

SSC

Well I'll tell you what...

I dont have the flow numbers. My 1st experiance with headders was on my truck. The truck already had good flowing dual exhaust on it and probably the best flowing manifolds avalible in 76. I installed a set of long tube headders with no gain in MPH or trap speed or increased fuel economy nothing. But on the Bird its a different story. The manifolds are tiny and very restrictive. I actually have two pairs of manifolds one from my car another from a 92 TBI and there identical in every way, saved them off a core engine thinking they might be better, no!

So I will agree on a good flowing system they probably will make little differece in my trucks case none but on a restricitve fbody the dont hurt.

Ricktpi

You are welcome. Your one example of no gains with headers vs. the literally hundreds (possibly thousands) on this board who have had gains proves to me at least, that your anti-header crusade is baseless. Obviously no one has flowed them or least they won't tell. So maybe you should flow them yourself & get back to us with your astonishing results.

five7kid

iTrader: (14)

I wouldn't put much "stock" in iron manifold flow numbers. Why? Because exhaust doesn't "flow", it pulses.

I know of two guys who run awesome numbers with iron manifolds: 1) A '90 RS, highly-modified ZZ3 (Bigmouth, SD TPI system, CNC ported heads, zero-decked, ZZ9 cam, 1.6 RR, dual cats, 4.10's, etc.). He took a die grinder to those manifolds and really hogged them out. He pulls 14.0's at 5800', which is low 13's at sea level. He's got a set of SLP's he'll put on when his health allows (he moved to Ft. Worth, or I'd help him get them on). 2) A '37 Chevy pickup with roots 383, runs 13.5's here (3700 lbs, 3.55 gears), with rams horn manifolds. He took a die grinder to those manifolds and really hogged them out. With the blower, flow area becomes more important than scavaging. They fit better in the narrow frame rails than any header he could find, anyway. Oh, last season, his passenger side manifold broke at the flange because it was so thin from the die grinding - he hanger-wired it up for the last month of the season until he could get another one fixed up over the winter.

The LB9/L98 manifolds are larger than LG4/LO3 manifolds, but the passenger side really necks down just above the y-pipe flange. Yuck.

FWIW, I had a '71 GMC 3/4 ton Custom Camper 350, dual exhausts, with similar rams horn manifolds. After the 2nd one broke on me, I figured a $75 set of 1-1/2 long tubes made a lot more sense than trying to find that increasingly-rare manifold - for which I paid $45 to replace the 1st one that broke. The difference they made in the way that truck ran was amazing, especially up here were power was down, anyway.

If a car slowed down with headers vs. factory manifolds, something wasn't done right - like tuning. You don't need extensive mods to justify headers, nor those mods to improve power with headers.