Are log designed manifolds that restrictive?

[--X--]

I am trying to find out based on real world data if this types of manifold are very restrictive as it is often suggested? In comparison to a tubular header. I have seen few ppl run logs and a great deal running tubular headers, are there any merits? of course this is on a 60degreeV6.

[Guest]

headers will make more power then logs.

[--X--]

Do you mind explaining the rational? Any logs? not talking about stock units just something designed to work well? I always hear the tubular headers is less restrictive, I can't seem to see why, if both systems are been connected to a turbo?
thanks

[Doubt_Incarnate]

it has to do with the timing of pulses, and velocity. equal length headers are equaly timed and deliver the same duration pulses in a strength tuned to deliver the power and power curve demanded by the builder. logs do not, they were designed to fit, and direct the exhaust gasses out. a motor balanced in every way is capable of far more power than a oem mass production motor, ls7 aside.

[SappySE107]

http://60degreev6.com/forumdisplay.php?f=84

Intake and exhaust tuning, and headers.

[timg]

If you search, there have been a few back to back dyno comparisons of logs vs tubular manifolds. In every case, the tubulars have made significantly more power. Full Race took a time lapse video of the whole thing. Check Honda Tech and google.

Tim

[--X--]

I apologise guys I am a dufus, I mean in a turbo application specifically. I know the same principles for NA cannot be the same when connected to the turbo right?
thanks again and sorry for the confusion. btw firefox and "search" are not friends

[timg]

The articles and tests I referenced were specifically for a turbocharged application.

http://www.full-race.com/articles/Bseriestest_writeup.pdf

http://www.full-race.com/articles/1.8T_turbo_manifold_test_writeup.pdf

There have been other tests (by independent third parties who had the same results), but these are the only two I could find with a quick search.

Tim

[ezrollin]

In most turbo installations it's not what you want but what will fit.Anyone thinking about making their own true equal length hedders for a turbo install better be prepared to do alot of painstaking work . A lot of so-called equal length hedders,aren't!

[--X--]

The articles and tests I referenced were specifically for a turbocharged application.

http://www.full-race.com/articles/Bseriestest_writeup.pdf

http://www.full-race.com/articles/1.8T_turbo_manifold_test_writeup.pdf

There have been other tests (by independent third parties who had the same results), but these are the only two I could find with a quick search.

Tim

Thanks Timg,
I just emailed a member and he gave me data, research papers and his experience. It seems for this lowly V6 it is better to use as he put it "a well designed log style manifold for very good response and turbine efficiency". Now I am so confused!?!?
Timg your data shows a typical 4 cyl, can that be applied to a v6? (according to member emailed the firing of this v6 will be well suited with a log and what he called "pulse turbocharing"
I am a

[Joseph Upson]

Forget the logs, get a pair of the new design cast iron manifolds with the 3500 heads, they have a very nice contour and blend down to the collector end as well as nice open ports internally. On a turbocharged engine given that scavenging between the turbo and cylinder head is not going to happen much if at all under boosted conditions the gain a set of headers will have over these manifolds on the same engine might not be significant at all. Look at them compared to that Fiero log style manifold which believe it or not the Fiero guys have documented flow well enough to not warrant the header install some have been doing for the Fiero V6.

Another very, very important advantage cast iron manifolds will give you over all except an exceptional and expensive set of headers is durability under the heat stress and that is very important and at least for me desired over say a 15hp gain I might get from headers. I've burned through a tube before, no fun having to rework turbo plumbing for that reason.

[gectek]

well i thought they had 2 diff designs of manifold/downpipe, one that went like the GA's and one that went under the oil pan around the front...

[timg]

There are benefits to log style manifolds and to tubular manifolds. Usually, log manifolds will be more durable but make less power. Tubular manifolds are harder to make, more expensive, less durable, but if done correctly will make more power than a log manifold. The four cylinder info and NA information all still apply to V6's.

Tim

[nocutt]

There are benefits to log style manifolds and to tubular manifolds. Usually, log manifolds will be more durable but make less power. Tubular manifolds are harder to make, more expensive, less durable, but if done correctly will make more power than a log manifold. The four cylinder info and NA information all still apply to V6's.

On the contrary...the info for the 4 cyl are applicable to v8s...not a v6s. You are absolutely right there are benefits to a tubular vs a "log style" mani...removing price both mani function absolutely different however done right on this v6s the "log style" will ultimately be more beneficial...

[SappySE107]

I was wondering when you were going to use that SN.

What kind of effect does the firing order play when you are talking about a turbo and the manifold/header design? I would expect the 1 2 3 4 5 6 firing order to work better either way having alternate firing on each bank compared to alternate/sequential firing orders between banks for other V6 and V8s. Inline 4 would be 1 3 2 4 right? I don't know what variations there are for a 4.