Exhaust flow potential

[klampy]

Hi guys, im seriously considering a remote turbo setup for the VR drifter.

so the question i want to ask, in a boosted setup, what sort of horsepower could the stock exhaust setup support? im being questioned as to why id choose extractors over the cast manifolds. and i believe they would be quite restrictive compared to extractors.

my idea/concept is to run (probably) pacemaker headers into a 2.25 cat back with the turbo sitting where the rear seat used to be and a 3inch diff dump.

so for next to nothing i could get a p/side cast manifold, stock Ypipe and a Stock catback (lengthened to remove the cat).

for $400 i can get lukey extractors.
for nearly $600 i can get pacemakers.

between different brand of extractors i would presume the difference would be marginal but between extractors vs cast manifolds, i would guess the flow difference would be quite different, (hence alot of people put them on as an "improvement" over cast's)


Discuss.

[Pub247]

Why a remote mount setup have yu factored in cost of supplying oil to turbo.

Turbo works effectivily on 2 solid princeples back pressure and heat. Rear mount system do not supply enough of these to justify the setup

[HoZy]

Rear mount system do not supply enough of these to justify the setup

Mr Pub, You couldn't be more wrong,

And Klampy, You will be wanting stock headers & 2.5" MAX, Preferably 2 1/4" for a remote mount setup.
You want exhaust temps & pressure to stay pretty consistant to the tip, An you will need to size your exducer housing to work on the temperature difference but to still be efficent up to the max RPM that you are after.

Cheers
Mat

[klampy]

YouTube - ‪STS Rear Mount Turbo Lag Demonstration‬‏
YouTube - ‪Late Model Racecraft's Rear Mount Turbo Camaro!!‬‏

i really dont think lag is going to be an issue. specially considering its going on a drifter so will be in the revs more often than not. off boost drivability isnt really an issue.

and oil supply is as simple as a longer oil line with a scavenge pump on the return to the sump.

and as far as pressure/heat, cooler gas is more dense. so in theory as long as i keep the velocity up to the turbine there should actually be more capacity for turbo speed once on boost.


so back to my question, im asking about pipe size, wether id go 2.25, or 2.5 and wether id go with proper extractors/headers vs stock manifolds/Ypipe.

[klampy]

Mr Pub, You couldn't be more wrong,

And Klampy, You will be wanting stock headers & 2.5" MAX, Preferably 2 1/4" for a remote mount setup.
You want exhaust temps & pressure to stay pretty consistant to the tip, An you will need to size your exducer housing to work on the temperature difference but to still be efficent up to the max RPM that you are after.

Cheers
Mat

you lost me on the exducer part. is that the turbine housing?

and you would seriously stick to the cast manifolds? i would have thought that extractor headers would flow better? as in, proper 3into 1 headers compared to the cast iron ones.???

[Pub247]

My comment said to justify the expense Why spend more money on a rear mount system when a proper setup works more effectivily and costs less. if your after a drift car i think response would be a factor, boost threshold would want to be minmal yet still retain high effeciency at top end.

As you said smaller turbine housing will solve your problems there but then you need go smaller again when you consider remote mount. then you have a lot of pipework to "fill" with boost before engine see a huge benefit .
You also have to supply oil to turbo which require a scanventge pump setup which might be simple but cost money.

Sure the losses arent great but there is a loss overall in all areas across the board.

So in essence remote mounts are a waste of time and money without justifiable reasons to do it.

If remote mounts were a worthwhile proporsition why dont not majority of turbo cars have them?

The only real reason for remote mounting a turbo system is when there is no room for them

[Pub247]

you lost me on the exducer part. is that the turbine housing?

and you would seriously stick to the cast manifolds? i would have thought that extractor headers would flow better? as in, proper 3into 1 headers compared to the cast iron ones.???

You might aswell make you whole system out of thick walled material more heat you trap the better which is why cast are better

[klampy]

its not "heat" that spins a turbine. its the expansion of the gas as it exits the head that is forced thru the turbine that makes it spin.

so in my theory (which is all it is at this point) says that once it has cooled slightly it can be pushed along at a consistant speed/pressure thru the pipe into the ex housing on the turbo.

[Not_An_Abba_Fan]

Heat equals exhaust speed though, the hotter you can keep the exhaust, the faster it will flow. A cold exhaust has a very small flow efficiency compared to a hot one.

I would still use extractors though as you also want exhaust velocity, extractors are way more effective at getting all the exhaust gas out of the combustion chambers, hence the name "extractor".

I will shamelessy plug myself here and say I can do Wildcat extractors for $385 shipped.

[klampy]

I will shamelessy plug myself here and say I can do Wildcat extractors for $385 shipped.

well so far your the cheapest as far as buying extractors go, so if and when i decide, ill send ya a PM.

and back to the flow rates n such, am i right to say that a 2.25 pipe off the extractors would be the way to go over 2.5 in relation to velocity?

coz when ur talkin about engine bay mounting, it was suggested that 38mm primaries into 50mm collector pipe would be suitable, so im wondering if that would still apply under the car? as in, would i be better off running twin 50mm pipes , one off each bank, right up to the turbo, as its a split pulse housing. compared to a single 2.25/2.5?

[one_and_only2004]

2.25" would be good for initial spool up speed, but it'd turn into quite a bottle neck higher in the revs.

[klampy]

iv just done some maths. but not entirely sure how to apply the results to what im doing.

i just worked out the cross sectional area of the different sized pipes.

2-1/4 pipe = 25.5 sq cm
2-1/2 pipe = 31.7 sq cm
2x 2 pipe = 39.3 sq cm
3in pipe = 45.6 sq cm

so can someone help me use this info to make an informed desicion rather than just guessing please?

i want to make 400+ hp at the wheels. so factoring in a 30% loss thru the drivetrain, is approx 530 at the fly. and id guess that power figure would happen around the 5000-6500 rpm range. so does anyone know how to work out what size exhaust pipe will support that sort of power?

and also what sort of boost it will take? im expecting 15psi +

[kiwicon]

you havn't even told us what turbo you are going to use yet.

[klampy]

yes i have. its in my build thread. but so that the info is here too, its a T70 with the 0.86? rear. its not the 1.something one. and not sure on the front housing size...

oh, and Ptrim make sense?

[kiwicon]

ahh so its an XS Power one then?? T70 is pretty big, and will easily make the HP you are after, what are you going to tune it with? a daughterboard or full standalone ECU? what about fuel supply side of things? actually I might go read your build thread, but IMHO Id go with extractors - brand named - not cheap chineese knock offs, run 2.5" in and 3" out and dump it at the diff

[acarmody]

So wait, you want to know if a single 2.25" exhaust is big enough to make 400hp? Or do you mean twin?

[klampy]

theres a few options there,

singles:
2-1/4
2-1/2

or twin 2inch.

single 3 would be way too laggy.

[klampy]

and im not sure what brand it is. all i can tell ya is its the rough cast compressor housing(not the shiny one), with a little blue tag, and 4inch intake flange. i bought it second hand but never used. so its still new. sorta.

and fuel is 840cc injectors (84lbs) and atm, a bosch 044 with a turbosmart FPR800. i may need a second 044 yet...
edit: and delcowizzid will be doing my initial tune so ill set up the delco however he requests it to be.

[acarmody]

OK I admit I know only a little about turbo setups and their subsequent exhaust, but if you have a fair bit of boost flowing into the engine, how car you going to get it out of the engine with a tiny exhaust thats better suited to a V6 N/A engine. Especially a 400hp car, I would think a 3-3.5" exhaust would be better.

[klampy]

so in saying that, you would think the same would apply to the turbo type headers when the turbo is in the bay. youd think the hotter gasses would require bigger pipes to flow through before they get to the restrictive turbine housing. but they dont, they use 38mm primaries and 50mm secondaries. which is what im leaning towards, the extractors would be 38mm primaries, (but longer than std turbo headers) and im thinkn id run twin 50mm secondaries( equivalent to the common crossover pipes) just a little longer as well.

im in the same boat as you acarmody, i dont know a LOT about turbos, but i do have a bit of theory. alot of it from reading lots and seeing what other people have done.

as far as flow is concerned, compare this to an L67 for a moment, for optimal performance they use 1-5/8 primaries, which is 41 mm and then they run twin 2-1/4 pipes all the way down, and that can support 400+ hpatw. but the difference starts where theyre trying to straight out remove the gasses compared to me trying to harness them, and (again in theory) as the gass cools it condenses, so if i dont go too big (ie: 2.5-3inch) i will be keeping up the velocity, and also keeping the pressure drop to a minimum and then the turbine becomes the restriction until the Dump and then it can be so short that it just becomes a nozzle instead of a pipe just to keep the flow straight as it exits the turbo. and they say that the less pressure on the dump side, the quicker it will spool. and i plan on the dump flaring out to 4inch, and not even 12 inches long. (diff dumper.)


if any of my theory is off, please learn me thats what this thread is for.

[klampy]

and too, i guess at the end of the day, the overall powerfigure isnt what im aiming for. if it can spin the wheels thru all the gears then iv won. thats what im aiming at.i wanna be able to spool up in 4th and light up the tires.

if it cant do that then i havent got enough. and it takes torque to do that. which is part of the reason iv stuck with the V6 and not opted for an RB, or a 2J just yet.


they do say theres no substitue for cubes. but i also wanna steer away from the V8 as i dont want an LS1, and iv heard it takes a fair bit of cash to make the 5L strong enough to handle this sort of abuse.

at least the Buick6 has been proven to handle a decent amount of crap.

[one_and_only2004]

You could also heat wrap the entire exhaust leading up to the turbo- that'd help the heat stay in the pipes a bit better.
You're probably going to have to consider a decent high flow cat as the stocker won't be up to the job. Are you in NZ or aus?

[klampy]

its a race car, so no cat. and in aus. nsw. coffs harbour. Ys that?

iv had a brief look at HPC coatings but thats also quite expensive.... i certainly would consider heat wrapping tho.

[one_and_only2004]

Ah sorry, thought it was registered. If you were in NZ I was going to suggest deleting the cat.
Heat wrapping is quite cost effective, procomp (in USA) do decent sized rolls for cheap so it wouldn't cost you much to do it that way. Don't bother with stainless cable ties - I just used fencing wire on mine and it never failed.

[klampy]

what about normal steel hose clamps? surely would do the same job?