transammiller

iTrader: (21)

just curious what everyone thinks of log style manifolds? I am in the works of a turbo 370 Miata. its kinda tight and stainless works headers arent really in my budget. i can put together some log style manifolds with 1.75" primaries and 2.5" collectors. someone on here mentioned too high EGTs (isnt that good for turbos anyway?) and inefficient design. anyone here built a set yet?

IT_SS

iTrader: (5)

theres a blue TT Trans Am that runs logs, I'll try and find the thread.....


here ya go https://ls1tech.com/forums/forced-in...a-build-4.html

camaroturbo

I have log header on my 383 sbc and am haveing back psi probs right now power falls off at 6000rpm and 18psi so I haveit had to much luck so far

transammiller

iTrader: (21)

can you post pics of the manifold design? iI'm hearing things also about backpressure problems and restrictions.

smokinHawk

iTrader: (48)

they will work, especially if you lack space, i dont you will notice any performance lost, main thing would be cracks so get thick walled material.

camaroturbo

here you go it made 650rwhp at 12psi 6000rpm the power fall off the back psi was about 3:1

Blownz28man

iTrader: (2)

I was kinda curious about logs myself. Especially have a stock manifold in stock postion one side having the pipe swing around to the passnger side, connect and have the passengerside primarys meet the single pipe then to turbo. Is that what u mean? I'd like to see some power numbers from that style

F8L GTO

Ive seen several cars make 800whp with a log style manifold set up. From what I've gathered, the upper Rpms will be the only place that you MIGHT notice a HP loss over a tubular manifolds.

LS1NOVA

iTrader: (12)

Check out LS4 manifolds too.

TT350

Where are you reading the back pressure at?
In one leg of the cross over or just below the inlet flange?

transammiller

iTrader: (21)

the truck guys do that.


I have a set of LS1 header flanges and i could easily build a set of logs for my upcoming 91mm build. I am thinking of building a set tubular headers but that is too much commitment.

camaroturbo

just below the inlet flange

TT350

You can’t blame the back pressure on the log manifolds
If your taking your readings from under the turbo inlet flange.

The cause of the back pressure is always down stream
of where your reading from.

It could be the turbine is too small, the A/R is too small
or the exhaust system may not flow enough.

But you can’t blame it on the log headers.

Not trying to bust your *****, just trying to help.

camaroturbo

naw is cool man I can use any help but I all ready did all that stuff and is left is the logs I got a 5" dp right now dump right down I went from a a/r .96 to a 1.32 with the biggs wheel I can get got a gt4788 and it did help for sure but still the back psi is still to high so idk wut eles to chg but the logs wut I could do is put it on the logs and see wut the back psi reads from there

Quik

iTrader: (7)

grand nationals been boosted over 2 decades ago and they came stock with log style setup

ive ran a Log setup for my truck made good power, i also fabbed a log setup for a Fbody as well

98SuperchargedLs1

iTrader: (1)

im also using log manifolds.. it was the only thing to use on my 65 chevelle ls2. should be done in a few weeks then i can get some dyno numbers. im only going to be running 8psi

camaroturbo

the thing I like about my log headers is I can get to all the spark plugs and thay fits real nice my car does make good power for sure and the gt4788 r know for back psi prob but a lot of people on here told me the logs had something to do with my back psi hope this helps