trying to figure out which route to take: all else being equal... any idea the difference in performance of an equal length exhaust manifold over a log style on an LS Vtec b 16 running 14 pounds of boost? trying to figure out weather the extra cost of a quality equal length is worth the performance gains. and secondly... i heard... log style may not have the power in the upper rpms, but the turbo will spool quicker... true? or is that a bunch of crap?

 

read the FAQ's then come back with a more in depth question(s)

 

for 14 psi of boost, depending on the turbo the log will lose out a lot up top but spool faster. however in a drag racing situation you're rarely in the midrange and always up top.

there were members here that got 400 on log style manifolds. with a proper tubular, you can make 400 with a less boost and less chances of detonation etcc

 

Best whp per price = Log.
Best whp per psi = EL.

 

A properly designed equal length manifold will spool faster than a log and give more top end.
For a quick spool you need a high gas speed and higher EGT's a log won't have the same gas speed as a well designed equal length.

That said if your on a budget, you might be better off spending the money elsewhere, i.e. getting a good tune etc.

 

I believe that statement is rather incorrect. Check your fluid dynamics a bit when it comes to the correlation b/w Exhaust gas velocity and volume per cubic meter. You've got it a bit backwards.

 

hey shodan/rickylee either of you interested in explaining a little more in depth about that? I'm a very beginning student of fluid dynamics and i'd really be interested in hearing the mathematic reasons behind the performance difference between log and E.L.
thanks!

 

Both manifolds are more than capable of making your desired power. I have made over 800whp with an inlinepro log manifold, but a quality tubular manifold will make more power AND spool faster. There are some good companies making affordable tubular manifolds these days like RCautoworks.

 

I switched from top mount to rev hard cast manifold. I made more power. I couldnt believe it. My tuner couldnt believe it either. I prefer cast manifolds personally.

 

You can still use a "tubular" manifold with shorter runners to keep exhaust velocity high. just be aware that when some people are using the term "tubular", they don't necessarily mean Ramhorn or topmount. It could be a "log" manifold using the higher quality "tubular" steel.

 

Equal length will generally spool the turbo up slower but make a bit more power. If not chasing every last hp a log manifold will be fine.

A more interesting question for me is does the added back pressure from a log manifold give you more chance of running into detonation problems? I am still using my stock SR20 cast log mani and a experiencing a bit of det under higher boost levels..

 

well the reason i ask, right now i have a b16 in my car but im looking to eventually buy a b18 and swap it over once all the work on it is finished, i would be swapping the head of the b16 onto the other block tho... anyways right now i have an ss auto crome ram horn style manifold (no jokes... it came on the car, obviously looking to replace it) but its cracked at the collector both back and front. to get it properly welded (with the chance of it cracking again) would be about $100-150 depending on where i go and if i yank it off myself... and i dont want to spend a dime on anything right now for performance if it wont work for the motor swap and turbo levels im looking for. i dont want to put money into the motor other than to get it running cleanly, but if i decent log manifold that would work for the b18 is only $300 or so i might as well make that purchase now and not worry about the manifold cracking any more...

 

SS auto chrome RUN!!!

do yourself a favor and goto spoolinperformance or RCautoworks and pick up a tubular log mani.

 

hahah hit me up ill see what i can work out for ya .. got a few manifolds here in stock on shelf ready go too !

 

I've had much better luck with the inlinepro logs than most any other log i've seen. I had a stainless steel log on my car at one point and it didn't make power. Swapped out for a rc autoworks ramhorn and doing much better. In general if you go with a log I would stick with a nice cast piece such as the inline manifold.

 

what
mini ramhorns

 

I actually had something very similar happen. I went from a topmount to an SLS mini ram and not only gained 4whp up top at the same boost level, but gained 40whp/40wtq in the midrange. Switching was definitely a good choice on my part

 

hmmm... interesting. Sounds to me like a log style is the way to go for the average enthusiast like me whose car will see little track time but will be street driven eery day.

 

^^That's probably true, but i would rather have a manifold with at least some sort of collector. That's why i opted for the miniram on my last setup. Its awesome for the street. You sacrifice a bit in the low end, but gain up top. Pair that with a good turbo and you're all set. I can toss up the comparison graph if you're interested...

 

We are starting to notice are few interesting things about the mini ram manifolds and the tiny collectors they are made with. I'm not saying its good or bad either, just some itneresting things seeing how these smaller collectors work out and perform compared to a ram horn style collector.

I also just want to state this because I get people calling every now and then asking about equal length manifolds. So many people are mistaken, and they think the ram horn is equal length, its far from it actually.

There is always a big debate about true equal length manifolds vs. tublar manifolds ( I.E , ram horn, top mount, mini ram ). I have never once seen an actually test done, and for the money its usually not worth it to go with a full equal length manifold.

I'd say the mini ram was just better for your setup overal.

 

Here's the graph of the difference. The setup other than the manifold is the exact same. The boost is the same on both dynos.

Setup was an STC GT3255b .63, 3" dp and exhaust, 2.5" IC piping, etc...

BLUE is the mini ram - RED is the topmount

 

So then how do you know at what point you shouldn't be running a mini-ram and up to a ramhorn? I always thought that the ramhorn was better but now I am starting to think that the mini-ram gives the best of both worlds of the log mani and the ramhorn. It gives you faster spool than a ramhorn which would help on my B16 but still gives you good power up top like a ramhorn would.

 

It's kind of a case by case thing based on the setup, turbo, goals, etc. There really isn't a definitive point at which a certain manifold is better than another one.

 

A thread like this quickly becomes vague and confusing... It is not possible to compare between a "log" and a "EL tubular" manifold.

Which type of log? Which type of EL tubular?

Let's see.. We have log manifolds that are constructed out of pipe "tee's" with cylinder #2 and 3 exhaust gases literally hitting a brick wall and forced to turn a sharp 90 deg. Those suck no matter what the setup is. You will lose spool and power with those, but hey, it's cheap to build and easy to make. We also have logs such as Inline-Pro that has proper dividers inside the manifold, wide radius primary bends and great design. We also have logs that are equal length too, such has a mini-ram horn with really short runners but has a full merge collector. Then we have shitty EL tubular manifolds, such as OBX or SSAC which has no merge collector and uses a box collector; that kills spool and power big time. All of a sudden, does that mean a log will outperform EL tubular manifolds? Nope

The only way you will get a straight answer is compare between specific brand and model manifolds, thus, drawing a conclusion that ie: Peakboost Ramhorn is better than OBX, because we know it's true and tests have been done. Or compare manifolds by design, long merge collector vs short merge collector, long runner lengths (topmount) vs short runner (mini-ram), etc...

So let's all skip this log vs tubular BS.... The question makes no sense, therefore, none of the answers would make any sense either.

 

Eq