Most power you've seen from a Log ?
 

I'm allways seeing Log manifolds getting a bad rap because they "dont flow well". What is the most power you've heard of some one getting with useing a log manifold?

Re:Most power you've seen from a Log ?
 

I've seen 500-600hp with the inline pro manifold. You can make high hp with a log manifold, its if you would change from that log manifold you'll make more hp alot easier at the same psi

Re:Most power you've seen from a Log ?
 

I think that, although these log styles have some disadvantages, they typically are made using piping that is quite a bit oversized. This decreases the velocity, which has other disadvantages... however, with decreased velocity, the flow characteristics are going to have less effect on performance.

In other words, if you were running much higher velocity (or smaller piping in the same shape) through the log styles, the bad flow characteristics they have would be much more evident.

Re:Most power you've seen from a Log ?
 

I'm not trying to call you out or anything, but have you seen your theory tested? I'm wondering if a test with a log manifold of large diameter compared to a log manifold of small diameter would show the exhaust velocity theory to hold true. think of it this way, the bigger the exhaust the better for turbo, but that's after the turbo, and the turbo is a restriction. Bisimoto uses fairly large sized piping for their NA headers, maybe he's found the sweet spot between velocity and cfm flowing ability.

Re:Most power you've seen from a Log ?
 

Yeah, think of it like a larger woman. If they're wearing baggier clothes, it isn't as noticeable, and they don't look terribly bad. However, if you see them wearing tight clothes, you want to throw up.

Re:Most power you've seen from a Log ?
 

Re:Most power you've seen from a Log ?
 

Lol you suck at teh quoting.

Re:Most power you've seen from a Log ?
 

I hate when people type in the quotes

Re:Most power you've seen from a Log ?
 

You can test this with a waterhose. Turn the hose on and see how far it shoots. Then reduce the cross-section of flow area by placing your thumb over half of it...and see if the water doesn't speed up and shoot farther. No dyno's needed to prove that when you reduce the area available for flow, while the mass through it stays constant, velocity is increased. Don't take this badly if it sounds that way, as I don't mean to sound like a dick or anything.
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That's possible, but it's also possible that he's found a size of tubing that is much easier to find or get bent, and the performance isn't enough "off par" to bother spending more money eleswhere. Of course we will never know, cause if you ask them, they'll say they did some extensive testing that nobody else can possibly comprehend...just so they defend their product and sound like hot-shots. I'm not saying that Bisimoto is bad or they lie..just that you have to consider the source of info. I think the odds of them admitting that they use that size pipe because it's cheaper is about 0%.

Look at Full Race and all the other big companies...they use heavy wall pipe. They will say that it's necessary...but somehow the prostock dragsters don't need that..hmmmm.. I think it's likely an issue of pipe fittings being easier to buy than bent pipe. It's also easier to cut, as it can be cut cleanly in a cold saw, where tubing is much harder. Also, when you cut tubing in mid-bend, it will egg shape due to stresses put in by the bend. Pipe fittings can be cut in mid elbow and the shape will stay round.

I think that in this industry, many companies will distort facts. They will tell you something's the best because it's what they use. They will say that one thing was tested and did best, when they likely never tested ----.

People are all over the nuts of the big header and manifold companies these days...and believe everything they say as if it were in the Bible...without questioning it.

Doubt what I say? The top companies will boast about "certified welders" and stuff like that... has anybody seen a copy of the certifications? Anybody ever seen what welding procedure the welders certified to? Anybody ever asked what welding specs they weld to?

Granted, that stuff may not be necessary, but I think that if a company says something, it should be true or not said. However, nobody questions these to companies..and therefore they believe whatever they say.

Kinda got off topic here..just a small rant.

Re:Most power you've seen from a Log ?
 

inline pro mani is hardly a log manifold ;)

Re:Most power you've seen from a Log ?
 

A cast manifold with no merge collector = teh log mani

http://www.errordownloadingcodec.com...29-05_1753.JPG


You put it next to the one Kyle made and I wouldn't be able to tell them apart :P

Re:Most power you've seen from a Log ?
 

http://www.inlinepro.com/catalog/images/IP-SST4-Lg.gif

Like I said.. hardly a log


http://i.xanga.com/yangsta3/crp%202.JPG

^^^ definatly a LOG

Re:Most power you've seen from a Log ?
 

Thats not a log


http://www.logscaler.com/Chevytrklog.jpg


^^^^This is a log

http://www.fast-turbo.com/Produtcs/F...3_SS_large.jpg


Yeah I can see its better than the homemade log mani's that people make but to me its still a log (the nicest out there) just becuase its still a cast and non merge collected. Merge collectors is what sells me on manifolds. What would you classify the inline pro mani as?

Re:Most power you've seen from a Log ?
 

a hybrid mani? ;) ^^ love the log picture.. google owns you

The inline pro decently merges the collectors into 1 dump, unlike a log where the flow is running directly into each other. But for 499 or whatever they cost its a huge ass rip off.

Re:Most power you've seen from a Log ?
 

Wow that really looks like an HF/CX/VX/STD Manifold!

According to Mike Kojima, log manifolds don't limit the horsepower on a turbocharged motor until around 400hp. Mike Kojima doesn't believe in the backpressure theory either, i remember reading a sport compact car once and they had an open downpipe sentra NA and it made more power than when it had an exhaust system. But mike kojima is a weirdass.

Re:Most power you've seen from a Log ?
 

equl length v log mani
http://fugu.trnetworks.net~geoff/movies/frmanifold test.mpeg

Re:Most power you've seen from a Log ?
 

Re:Most power you've seen from a Log ?
 

Re:Most power you've seen from a Log ?
 

full race have a good vid of equl length vs log mani test
ive tryd to post the vid but this sites haveing probs

Re:Most power you've seen from a Log ?
 

ill stuff my testicles in the collector

Re:Most power you've seen from a Log ?
 

NA is different then turboed.
You need some kind of backpressure especially on mostly stock NA engines...

Re:Most power you've seen from a Log ?
 

The back pressure theory is about flattening the power band, so it won't suck as bad.

Re:Most power you've seen from a Log ?
 

I'm not sure what you mean by that, but I think it helps with "scavenging" of the exhaust gasses. My way of thinking on this is that it creates some kinda "suction" to pull out the gasses.

Exhaust is gas flow, heat and a pressure wave. All of the designs are a compromise - logs hold the heat better, equal length distribute the pulses at more even time spacings and have better gas flow.

From what I've read, for a yutz like me at 7 - 10 psi it makes no real difference. When you start really going balls out, like 300+ HP, the difference might be like 5Hp or something. You could probably get more by porting the head or something.

Re:Most power you've seen from a Log ?
 

Old MYTH....not true at all. Backpressure is something you don't need. Just look at the dragsters that run 3" open pipes that are only about 2 feet long. They aren't worried about backpressure, only providing a way to get the heat away from the engine.

Re:Most power you've seen from a Log ?
 

what you guys are forgetting is that most turboed engines run about 30-50 psi of exhaust gas into the turbine inlet of the turbo, so if you have bigger piping and more flow and velocity out of the turbo (its a velocity vs flow problem) you have to have enough volume in the runners that it isnt restrictive but they cant be soo big that youre losing velocity all over the place, with a log manifold and no real collector, the velocity is all messed up because the exhaust gas has to make sharp 90* turns and isnt forced primarily into the turbo (as opposed to other runners etc) so its not as efficient, whereas an efficient collector on a race manifold smooths out the sharp turns and prevents a loss in velocity and makes more power due to the better scavaging