Hello all I would like to know what's your recommendation when it comes to the exhaust for running twin turbo's on a 72 455. This is a non ac car, so I felt it to be a likely candidate to be a sleeper. Let me know what you think headers or manifolds, what diameter would be best, what muffler to get the best performance and sound, would I need to run a x pipe? I don't know!!! I just need to get the exhaust done and I want to have it ran for my future plans so I don't have to do it again. Thanks in advance
3in duals min. 3.5 would work well too turbo headers would be alot lighter, but cant beat manifolds for durability sand ground clearence if you plan to lower...or just have a staggered height tire combo! I too plan to do the sleeper look either going to go 295-50 rear 245-60 fronts or 265-50s all around 1.5 drop all around too
So I could run the manifolds and the twin turbos???? I thought this would be too restricted. So with 3" exhaust should I use a x pipe or no, and would my selection of muffler make a difference?
i'm personally going with pypes performance 3''exchange system(x-pipe with electric cutouts) mark burtons manifolds are specifcly designed for turbos he also makes turbo headers ps, can't run stock manifolds nor aftermark headers, has to be turbo specific
x-pipe will not make a difference since the turbo's get rid of all the exhaust pulses...and as far as mufflers go just get a bullet type muffler, if you cant see straight through it, dont use it
yea, the crossovers with a turbo system might just make things a bit quieter, my only reasoning is that pypes makes a 304 ss ready kit...that and electric cutouts right off the x is a cool feature..will spool a turbo faster
the exhaust cut outs will not have any effect on your spool time, they can reduce you back pressure in an improperly designed setup but as long as you can run 3in down pipes, and 3in dual exhaust you wont have a problem with the right size .ar on your turbos
you sure....a free'er flowing exhaust helps turbo spool...thats just what anb electric cutout does also would a 3.5 dp to 3in duals be better for us v8 guys
back pressure makes a turbo spool, aka the size of the turbo exhaust housing (.ar)....smaller .ar spools faster, but to small will create to much back pressure in the rpm's and then choke you out up top, so its just a fine line. and if your running twin turbos, and your running them both down the firewall and out the back, dual 3in will be plenty...going from 3.5 down to 3in wouldnt do you any good cause then your smallest piping is still 3in and it would be just the same as running all 3in. BUT if you wanted to run some exhaust cutouts, and some smaller dual exhaust so that it fits easier just put the cutouts before it transitions to the smaller piping and run the cutouts on a wide open throttle switch like on a nitrous setup, so that they open automatically and remember, the turbo acts as a muffler itself, so it will be quieter than you think
what are you power goals? some twin MP t4 70mm turbos with the .68 ar would spool fast and not choke you out up top, assuming around 6000rpm redline your 455 will have some good power without boost, so you wont need insant boost anyways, sometimes lag is a good thing
ok, I was just thinking like this...turbos work off engine load...which is pretty much the cold side, which you want to be hi backpressure. haveing less backpressure on the hot side should mean better flow and in return make the turbos spool a couple hundred rpms faster
Cold side= from turbo outlet to intake Hot side= from heads to turbo just run the 3in downpipes with a straight threw muffler and youll be perfect spool time comes from the hotside, not the down pipe or exhuast to small or a dp or exhaust makes the turbo/engine "choke", kinda like running to small of a header
see someone thinks like me lol you want the exhaust to leave the turbine side quickly as you can. this is why everyone upgrades to a bigger diameter exhaust.. this point cant be agured though... less back pressure on turbine side mean more power, this is why turbo manufactures revised the flange style..3bolt, 4bolt, 5bolt to the best flowing v-band dp flange I'm going to read that link too, even on the internet the whole thing is about 50/50 on the bigger dp and cutout thing..
heres a snipping from the link dawildcat posted The exhaust system before the turbo and the turbo itself have a greater effect on backpressure than the exhaust behind it. You want the least restriction after the turbo as possible for both top end power and quick spool-up. p so, bigger exhaust as you can fit. or cutouts which will essentially have the same effect
Ok guys so everything that i've read I've arrived at this conclusion. In order to run the twin turbos, my best option on the exhaust end of it is to run headers. Is there a such thing as a 3" header????? Does it matter if I run a shorty or long header? As for the exhaust 3" all the way back and muffler's that have no internal baffling, and no cross over. Now for running these turbos can I add this to a stock engine or would I need to change anything such as header's, intake, carb etc.????? I'm new to all of this, let
Works with stock engine wouldnt go past 10 psi...6 or 8 will do ya well with a 455 3in exhaust will do ya well as for headers or manifolds, go to whichever you prefer for whatever reason(justa350 makes them both) as for things needed to run on a carbed engine: BLowthrough carb ie. csu,quickfuel, or holly 4150 modded for blowthrough you'll need an fuel pump block off plate electric fuel pump like an aeromotitve a2000 or fuelab pump you'll also need a fuel pressure reegulator with boost reference, again, fuelab or aeromotive Think I mentioned everything if not someone will chime in.
Thanks for the plug Mike! I think he is asking what to run for now though, in preparation for running turbos later. If so, I would suggest full length headers, and 3" pipes with no x-pipe. That will be reusable and easy to hook up to later. I run full mandrel 3" with no mufflers (other than turbos) and it sounds like a typical non-turbo car with flowmasters or similar.
