Jump to content
SAU Community

Recommended Posts

Ok I'm starting this post to see what is working for everyone.

My new engine is a 3025 neo built engine and I want to maximize its performance. 

Old system is a 3inch turbo back 100 cel cat straight through muffler.

Was thinking about doing a 4inch dump pipe to 3 inch from dump back.

 

Link to comment
https://www.sau.com.au/forums/topic/466345-exhaust-system-setups/
Share on other sites

You don't need anything crazy if you venting gate to atmo and run no cat..

If you not..good luck with that .., just take of exhaust on dyno before you piss fart around remaking stuff

400 should be a walk in the park for a 3 inch exhaust..

cheers

darren

Edited by jet_r31

The smart* approach (fully fully custom) is to route the wastegate pipe back in behind the cat.  Face it, the gate is not open very much of the time on the street, therefore the vast majority of the time all the gas is going through the cat.  Then when you really need the gate to flow lots of gas, you're not also requiring the cat to flow lots of gas.  Win.  Was it dose pipe Johnny who's done basically this recently?

 

*Only smart until you actually do get some sort of EPA/police attention, in which case it's not actually legal.

1 hour ago, GTSBoy said:

The smart* approach (fully fully custom) is to route the wastegate pipe back in behind the cat.  Face it, the gate is not open very much of the time on the street, therefore the vast majority of the time all the gas is going through the cat.  Then when you really need the gate to flow lots of gas, you're not also requiring the cat to flow lots of gas.  Win.  Was it dose pipe Johnny who's done basically this recently?

 

*Only smart until you actually do get some sort of EPA/police attention, in which case it's not actually legal.

Yes Johnny did this and ive copied plus merged it later for good measure ?

3 hours ago, lcxu105 said:

So a 3 1/2"dump 700mm lone back to a straight through 3"with 100 cel cat with 50mm wastegate merged back in the 3" pipe should be able to handle 420 to 450rwkw?

i had a 3.5 inch dump, then a 3 inch with a slight offset lukey and a resonator on my r31. It ran 141mph through the mufflers on 25psi with a auto

it was quiet exhaust but with a vented gate 

My mate had same mufflers in his vl turbo( manual)  as he copied with a 3582 turbo on upper 27psi, but with a 3 inch dump..he ran 138mph (you work the power out out) on a 3582 1.06 turbo , he dropped the exhaust  at dump and it made 10rwkw difference...Had a vented gate

No meows..

 

It really really comes down to vented gate..if you don't vent it..good luck. You need a f**koff big exhaust. Just like a Gtr with the twins replaced with upgrades...

or perhaps merge it a long way back. But thats a p.i.t.a

honestly you just need to test it, as different mufflers and cats pose different restrictions..even in same sizing..

cheers

darren

 

  • Like 1

Interested to see what difference venting the gate to atmosphere would make with my set up. Currently running a 4" dump to the bellhousing and then 3" from there through a single round muffler after the diff. Single cam RB30 with a powerglide. Head is stock besides slightly oversize valves and a small 218 @ .050 wade cam. Making 396rwkw with a 1.06 gtx35 on 30psi. Basically stopped making decent gains in power with more boost and inlet temps rising quite fast. The gate plumbs back in maybe halfway down the dump pipe. Would it be much more efficient going to atmosphere as I presume a fair amount exhaust flow would be through the turbo at that boost level?

I didn't have a chance to dump the exhaust last time on the dyno to see if any gains were to be made but I guess the stock ports in the head would be holding things back a little also?

44 minutes ago, PSI086 said:

Interested to see what difference venting the gate to atmosphere would make with my set up. Currently running a 4" dump to the bellhousing and then 3" from there through a single round muffler after the diff. Single cam RB30 with a powerglide. Head is stock besides slightly oversize valves and a small 218 @ .050 wade cam. Making 396rwkw with a 1.06 gtx35 on 30psi. Basically stopped making decent gains in power with more boost and inlet temps rising quite fast. The gate plumbs back in maybe halfway down the dump pipe. Would it be much more efficient going to atmosphere as I presume a fair amount exhaust flow would be through the turbo at that boost level?

I didn't have a chance to dump the exhaust last time on the dyno to see if any gains were to be made but I guess the stock ports in the head would be holding things back a little also?

What fuel are you running? 30psi i would expect to see more hp than that 

On 8/24/2016 at 7:10 PM, PSI086 said:

Interested to see what difference venting the gate to atmosphere would make with my set up. Currently running a 4" dump to the bellhousing and then 3" from there through a single round muffler after the diff. Single cam RB30 with a powerglide. Head is stock besides slightly oversize valves and a small 218 @ .050 wade cam. Making 396rwkw with a 1.06 gtx35 on 30psi. Basically stopped making decent gains in power with more boost and inlet temps rising quite fast. The gate plumbs back in maybe halfway down the dump pipe. Would it be much more efficient going to atmosphere as I presume a fair amount exhaust flow would be through the turbo at that boost level?

I didn't have a chance to dump the exhaust last time on the dyno to see if any gains were to be made but I guess the stock ports in the head would be holding things back a little also?

I wrote a big post and it didnt work. Cbf again

My mate morgz on ct ran 3 inch dump/exhaust plumbed back

With a 3582 with billet 67mm  comp 1.06

Went 10.20@140 -30psi-auto-450rwkw..made no more power

He unplumbed gate and it went straight to 40psi and maxed fuel system out in the midrange where peak torque is. Had to plumb it back..lol

So maybe worth a look

Cheers

Darren

 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • For once a good news  It needed to be adjusted by that one nut and it is ok  At least something was easy But thank you very much for help. But a small issue is now(gearbox) that when the car is stationary you can hear "clinking" from gearbox so some of the bearing is 100% not that happy... It goes away once you push clutch so it is 100% gearbox. Just if you know...what that bearing could be? It sounding like "spun bearing" but it is louder.
    • Yeah, that's fine**. But the numbers you came up with are just wrong. Try it for yourself. Put in any voltage from the possible range and see what result you get. You get nonsense. ** When I say "fine", I mean, it's still shit. The very simple linear formula (slope & intercept) is shit for a sensor with a non-linear response. This is the curve, from your data above. Look at the CURVE! It's only really linear between about 30 and 90 °C. And if you used only that range to define a curve, it would be great. But you would go more and more wrong as you went to higher temps. And that is why the slope & intercept found when you use 50 and 150 as the end points is so bad halfway between those points. The real curve is a long way below the linear curve which just zips straight between the end points, like this one. You could probably use the same slope and a lower intercept, to move that straight line down, and spread the error out. But you would 5-10°C off in a lot of places. You'd need to say what temperature range you really wanted to be most right - say, 100 to 130, and plop the line closest to teh real curve in that region, which would make it quite wrong down at the lower temperatures. Let me just say that HPTuners are not being realistic in only allowing for a simple linear curve. 
    • I feel I should re-iterate. The above picture is the only option available in the software and the blurb from HP Tuners I quoted earlier is the only way to add data to it and that's the description they offer as to how to figure it out. The only fields available is the blank box after (Input/ ) and the box right before = Output. Those are the only numbers that can be entered.
    • No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
×
×
  • Create New...