1 3/4-1 7/8 stepped vs. 1 7/8
 

hey there, are there any dyno sheet comparisons for 1 3/4" stepped headers to 1 7/8 vs. full 1 7/8 headers? ive been searching and searching but cant come up with anything. has anyone used stepped headers and then gone to 1 7/8 and seen a difference? thanx

oh also, just from hear say, some people say that using 1 7/8 is a waste of money, that there really isnt any more benefit when using this large of primaries compared to 1 3/4 stepped headers. others say that there is huge performance gains compared to 1 3/4 primary headers. any input to shed some light on this subject?

I have never seen a comparison between thoose 2 but I have seen 1 3/4 vs 1 7/8 headers and the 1 7/8 lost nothing down low, picked up 8rwhp at peak and a little bit mid range.

hmm, cool

Yeah all the comparisons I've seen have showed no loss down low and more gains up top. The problem being these are usually comparing a budget 1-3/4 header to a high-end 1-7/8 header. That said I'm probably going to go with the 1-7/8 headers when I get mine. Bigger is better right ;) ?

Why is there barely any information on stepped headers? It seems like no one runs them.

see thats what i would like to know also. it would seem like 1 3/4 stepped to 1 7/8 would be practically the same as all out 1 7/8? it would be nice if someone had a dyno sheet even just comparing 1 3/4 to 1 7/8 on the same engine.

also when would be a good time to upgrade to 1 7/8 to get more performance?

From what I understand is that the step head is supposed to scavenge better. Most step headers that I have seen are considered a race or competition headers. I am going to run a Edelbrock Victor step header on my car. I actually have a set of new 1-3/4 set of jet hot headers and a extra set of new Edelbrock Victor step headers for sale. If you are interested, let me know. Ill make you a heck of a deal on them.

I'm curious about stepped too. They seem like they'd be more effective at scavenging because of the design vs. the regular. Seems that no one runs them though so there must be some reason.

Well supposedly 1 7/8 helps a little on the top end and loses nothing on the bottom end on even a stock motor, and only helps when you do heads/cam. However....

https://ls1tech.com/forums/dynamomet...results-2.html

So while bigger headers are definitely better at some point, it's all about the total combination of things....I guess

no i dont need any 1 3/4 headers. i have a set of FLP 1 3/4 stainless LT's on mine.

a friend of mine told me a while back that there really isnt any perormance gains from 1 3/4 to 1 7/8 primaries, at least none that are notable unless you're running an all out race motor that revs high, but the 1 3/4 stepped is better for street motors. and i mean this guy is all LS like the rest of us are and i started thinking about it a couple days ago. but it would seem like the stepped are better because once the 1 3/4 primary steps up to 1 7/8 it would be literally sucking the exhuast out of the cylinders to fill that space. kinda like putting a syringe on your thumb and pulling the plunger on it till it resists, then pull your thumb off the opening and you can hear the air being sucked into the syringe to fill the vacuum right?

That's the whole point of headers, to create a vacuum to suck the exhaust out of the cylinders. If you ran a car without headers it would make less power. So yeah it seems that stepped would be better

I have also heard that stepped headers create a better scavenging effect, yet I still don't see anybody using them.

i wonder why. is it because of the texan attitude, bigger is better, all or nothing? but turns out that some times the bigger is just the same as the smaller, huh.

would be nice if someone with exspertise from the exhaust industry would chime in and give some input.

I don't have very long to reply or find the thread that I originally read this in, but I believe I remember reading that stepped headers do create a better scavenging effect, but that it is focused for a more specific RPM range instead of the entire band. That's why they are for racing, where you intend to be in x-y RPM band for the majority of the time.

Wish I could help more.

wish there were more detailed info on this

That makes sense. Header length also corresponds to specific RPM range. I'm sure professional racers spend lots of money to get the right step & length for their specific RPM band. But as with many things race parts don't always translate well to the street. I'd hate to have a street car with headers that were only working best at 5 or 6k.

ha, would be getting a lot of tickets for either noise or speed.

The stepped edelbrocks looked nice but you have to weld the collector on which caused a lot of exhaust leaks.

The stepped header is supposed to make the torque of 1 3/4 with the topend power of 1 7/8

any info to back this up?

Very curious about this also.Would like to know more.Mr. Tooley can you give us anymore insight to this?I need to pick something out for my setup and have been wondering what would work best with my new heads (stage 3 AFR's on a 402)With a 200 shot,and six speed

hey there fellow arizonan. im in safford, about three hours from the phoenix area.

I can't see there being enough of a difference between the 1 3/4" and 1 7/8" to necessitate a stepped setup. The "stepped header is supposed to make the torque of 1 3/4 with the topend power of 1 7/8" isn't really true because the 1 3/4" doesn't make any more torque than the 1 7/8 at any point.

Also, going small to big slows exhaust velocity, so to increase scavenging (at least based on what I've read), you'd actually want a 1 7/8" header that steps down to 1 3/4" - that way, the velocity increases in the smaller pipe diameter, causing better evacuation in the larger diameter pipe. I can see how having the smaller diameter at the exhaust port would increase velocity there, but you're still going to lose velocity, and thus create turbulence, when you bump up to the bigger pipe diameter.

It'd be interesting to see this kicked to advanced tech to see what the smart guys think.

i read this out of this book i bought dyno-proven gm ls1 thru ls7 performance parts by richard holdener

test engine was a ls2 on a engine dyno with open headers. quote in this case replacing the 1 3/4 hooker competition headers with custom step headers resulted in a sizeable power gain past 4500. The custom step headers were worth as much as 13 hp over the smaller hooker on this ls2 appplication . The step headers improved the torque above 4500 rpm but lost 6 to 8 ft-lbs down below 3500 rpm. the custom steps were 1(3/4) stepped to 1(7/8). the test engine was a stock gmpp ls2 crate engine equipped with a fast 90/90

if you are already running a 1 3/4 header then there is no point at wasting money for 1 7/8 header. But if you do not have any headers and are in the market to buy some, i would go with 1 7/8. TSP sells 1 7/8 priced around 5-600 bucks i think.

thats interesting, maybe not worth 500 bucks for 13 hp, but none the less

Open headers on an engine dyno isn't enough of a real-world scenario for me to really give that test cause for considering stepped over regular header primaries. It also doesn't compare the stepped headers to 1 7/8" primary headers.

i can respect that, i would like too see if thers is less of a change from the comparison from stepped too 1(7/8) there is such a variety of lt's its hard and expensive to test on a specific engine combination what would be the best for your application comparing a stock 347 with cai or a 408 stroker for me i bought tsp ceramic coated 1(7/8) for my camaro and love them and came with 02 sensors and ory all the connections and shipped for 800 bucks and the fitment was great :nod:

It would be nice if Kooks,or ARH came in to discuss this with us...

agreed, get some first hand knowledge. there is alot of good information in here

is there any other input on this subject that anyone else would like to share?

Anyone from Kooks,ARH,TSP or anyone with good info,help us out.

up top

have fun with them 1 7/8's.... tighter than a virgin on prom night i tell ya!

stupid question here but what are "stepped" headers? Never heard that term before. How are they different from typical aftermarket header?

The tube diameter changes - hence "stepped" - between the header flange and the collector. A 1 3/4" - 1 7/8" stepped header would have primaries 1.75" in diameter at the exhaust flange, and then at some point the diameter would expand out to 1.875" and continue to the collector.

A typical header has a single diameter primary the full length.

oh ok cool thx

man i wish a sponsor with alot of knowledge about stepped headers would chime in and give us some wisdom on how they're designed and what they're designed to do

LOL who's the Sam Strano of headers and exhaust systems? :D

Back again,anyone?

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Nothing to add other then I went through this when I ordered headers. At the time the general consences was the 17/8 was too large for a stock cube motor. Thinking that I would eventually want to go to a bigger cube motor but didn't want to loose torque with the 347 I choose stepped.

did you discuss this with kooks when you ordered your headers?

Well, when I was building headers for my 1989 Trans Am I did a lot of research and talked to quite a few people in the business. As said above the idea is to keep the exhaust velocity up and this will improve the scavenging process especially during the cam overlap period. This probably what the 1 3/4" headers do.

I also learned that around the first 8" of the header is the key velocity wise. Now say after the first 8" stepping up to 1 7/8" the rest of the way will help reduce any back pressure and if the step is done properly will also help in reducing reversion. Every time there is a bend in the tubing there is a loss of flow. A larger tube will help in reducing that flow loss.

However in order to fit the long tube headers in our cars bends are a necessary evil. The bigger the radius the better but again to fit the headers in the car we have to use a radius that allows the headers to fit in the space allowed.

By the way when I engine dyno tested my motor I compared my home-built 1 3/4" "shorty" headers to the dyno rooms long tube headers. There are reasons I have to use shorties so don't even ask. Hahaha. The results were below peak torque the long tube headers were better. Above peak torque and we are talking 5000rpm to 6500 rpm the dyno room headers were better by just 1+hp on average.

wow, that is very interesting. so i guess, and correct me if im wrong, from what the above poster is saying is confirming what i thought to begin with. That you still get the torque with the 1 3/4 primaries and get the peak power with the 1 7/8 stepped, which would be best for a stock cube ls1 or 6.0.

I would love to see some dyno graphs of some comparisons: hint hint to some sponsors