exhaust manifold flange design

[Skylar]

Hi,

Drew the below flange up today but looking at other manifolds I've noticed they cut away material that's not really needed. Is it for thermal expansion or just weight savings or some other reason?

My plain drawing:
http://www.ae86drivingclub.com.au/dcimages/2/0/2/5/52452.jpg
Other manifold flanges:
http://www.ae86drivingclub.com.au/dcimages/2/0/2/5/52479.jpg

'nother thing: at ~700 deg C, that flange will get ~3.6mm longer while the head gets ~6.2mm longer, so in theory, the manifold opening won't meet the port perfectly. Should I draw the flange up to take that into account? Looking into it too much? Probably shoulda used a manifold to map the flange off and not the head, maybe there's a difference.

[--Redwork--]

I'd say that the removed material is aas you suggested both for heat expansion and weight.. But mostly heat...

Also. While the Exhaust manifold may get close to 700 the head will not...Not even close.. Just make the manifold port a fraction bigger if your concerned about them not lining up quite right..
I've seen some absolutly horrid looking manifolds that have actually worked really well.. Turbo applications though.. NA headers are an art form best left to the elite.. eg very few.. and I do mean "FEW" ppl are cappable of making really good NA headers...

[Skylar]

My manifold's going to look so goofy. The exhaust housing is too big to fit in between the head and the strut tower so it's going to have to be mounted pretty far forward. Hopefully I can get a decent looking mani that's close to equal length and points the gas at the turbine and not just get it to the turbine housing.

When you say horrid looking, do you mean unequal length or real bad entry for gas into the turbine housing? Like no. 1 runner on most jap low mount SR manifolds.

[redsprinter]

i know it obvious but wouldnt you just get an exhuast manifold gasket and trace it onto the material you want to make the flange from ???

[--Redwork--]

Horrid as in differnt sized pipes butting up with no intergration. Bad angles on pipe to bends ect.. Just nasty looking.. Sorry I have no photos.

Equal thenght is not important on turbo headers.. Length and heat are far more influential in how the manifold will work.
You have to remmeber a Turbo manifold uses mostly heat energy and flow to get the turbo spinning. Not preasure wave pulses like NA manifolds use to get the best scavenging.

[Tim.duncan]

I looked into turbo manifolds a little bit and endded up buying a book on it which was a big help!
keep it as short as possible and the piping as thick as possible, like redwork said its the heat trying to escape past the exhaust wheel that spools up the turbo not the "gas flow"
also look into pulse manifolds where ports 1,3 are separate than 2,4 to allow a pulse into the turbo for quicker spool
with the flange make it at least 10mm thick, i would go 12mm weld it all up then get it machined back flat

[Skylar]

Redsprinter, don't have a gasket. but I have 3 heads I can use to map the ports and studs off.

I was going to use 12mm and get it machined flat but everyone sells 10mm for the head side so I think I'll go with that. Sorta disappointing but I found a place that sells 10mm flanges for most common cars for 40 bucks each so I think I'll get that. I'll get the turbo side cut in 12mm though.

I read somewhere (PF maybe?) that turbos want to see pulses and not a constant stream but I do agree with the heat. As much as I want to keep it short no. 4 runner will have to be at least 18" long and the others will have to navigate around it. I'll get it ceramic coated and maybe heat wrap it too coz I still got a whole bunch of it lying around.

I'm a bit skeptical on doing split pulse manifold for non-split pulse turbo. I've read that the runners be arranged into the collector to make the flow "swirl" into the turbine housing. Not sure about that either.

I'm going to use sch. 10 stuff if I can get it. I see sch. 40 being overkill especially since the manifold won't be supporting the turbo's weight.

[Sam-Q]

which book did you buy Tim?

[biggo]

You say you have little room? My old turbo mani had runner 1 join into runner 3 then into flange, so in theory it had a 3 flange collecotor. Could work in your case?

Why not go log style?

[Skylar]

It's not the manifold having no room, it's whether the turbo will fit where a turbo normally sits. Last time we test fitted the turbo (last year) it didn't fit. me and mate were talking about it today and I'll test fit again tomorrow but try to make it fit this time. I'll get a picture to show you what I mean. Might have to remove aircon :( or downsize the turbo. :(

[Skylar]

OH BOY! It FITS!
http://www.ae86drivingclub.com.au/dcimages/2/0/2/5/52777.jpg
Gonna need some heatshielding.

Probably didn't fit last time because the standard resonance box was still on the strut tower in me mate's silvia.

Biggo, I could to log but the turbine opening is bigger than T3/smaller than T4. Even with 1/2 and 3/4 linked it won't fill the area. Not that I've looked hard at it but it's probably not going to need a real 'collector' as the flange opening should accommodate 4 pipes.

[--Redwork--]

That a HX300sx thingy... Holset /Borgwarner turbos are big MOFO's.. That looks like it'll fit in there nicely..
Mate has a gt35 on the SR in his little datsun 1200 and that has less room than your car.

[Skylar]

Haha, you just mashed BW/BEP S300 and Holset HX30 together to make HX300sx. and it's neither of them. S300/HX30/GT35 are still 'regular' turbos with normal turbine A/R's so the comp cover usually clears the strut tower by being forward of it while the turbine housing fills the space between strut tower and head. Mine's a HE351VE with a 1.5 A/R rear housing which is why I was worried about it not fitting. The exhaust housing is bigger than the comp housing. It has a 'exhaust deflector' or something in the turbine housing to make the turbo spool quicker and exhaust brake diesel truck style which is why the rear is so big.

[--Redwork--]

1.5 ar.. REALLY.... I have seen some divided style housing where on side of the housing gets block off to force the air through only half the area untill it get moving, but a 1.5 is A BIG housing..

And can you tell I'm not reall up to speed on the BW Holset range.. I know they're cheap though... :)

[biggo]

You said you wanted a daily. THis goes above and beyond the call of duty. The SR's timeline shall be henceforth measured in minutes.

[Skylar]

bro, it's spend 695USD on a t3/t4, spend 500 on a shitty S15 T28 or use this turbo that I already have. get where I'm coming from? I didn't wanna use it either but cheap.

Current SR's life is limited anyway, high k's and makes rattle noises on start up. thought it was just exhaust but always shuts up in under 5 seconds so guessing it's engine related. Got another SR to put back together so we'll see how long it lasts, with me tuning it.

and since corolla passed engineering that can go back to being daily. :)

[Nikkojoe]

lol, a ca18det ke70 as a daily and a stock s13 with a stupid turbo as a.....?

[Skylar]

Back up race car/daily + dyno queen?