Thread: Pulsing the turbocharger...

my issue is with a divided T4 with a giant AR on a small displacement v6 with a rotating assembly thats better for making power down low/mid range rpm.
i have a feeling your leaving a ton of under the curve performance off your car.

i doubt its a divided T3, which at least the area of the one port is just a hair bigger cross sectional area as one exhaust port.
a divided T4 has each port a good bit bigger than each of our intake ports. no mater what you do with the piping that increase in cross sectional area is creating a pressure drop as it enters the turbine scroll. sorta not what the pulse tuning is about, kinda hard to keep that pressure wave energy moving when the area of the pipe increases as much as it does

and since pulse tuning is to help at low/mid range Rpm's by spooling the turbo....youd probably make way more power at the bottom half of your curve if you kept the exhaust gas velocity up.
ive seen guys get around large AR turbines by running the pipes through the flange and leaving them long enough that they form to the inside of the turbine scroll artificially reducing the AR and keeping the pipe volume/wave speed constant.


im just saying that we were lighting off the turbo before 2700 rpm, and made of 400ftlbs of tq at 3k rpm with 500 ftlbs by 3750, 575 by the time we got to 5k. HP got to 608 by 5400rpm at a lean fall off due to fuel pressure dropping. we did that at 18psi and our compressor is good to 26.
primary's are 1.625 od and secondary's are 2"

im really just saying youd do more for your lower rpm performance if you at least swapped out the turbine housing for a .68 AR and kept your current piping.

if that is a divided T4 with that big of an AR id figure on you moving the bottom end of the Tq curve another 1,000rpm closer to idle and not change your current power peak even though the tq curve would be higher nearly the whole way down.

that or youd get a bump using a more powerfull squirt using one of the sound performance/others scroll closing plate (really only for open collector merges)

meh i like discussions. i spent alot of time talking to turbo buick guys doing the math for our stuff.

its a great motor but when they shortened the deck height and made it a much higher rod/stroke angularity....they sorta killed the top end

Originally Posted by jbunla

Good luck too, not sure if you are being funny about the road warrior comment?





Are you serious? who says that? RR is about improving your time? I think you guys are simply just talking now. Thanks for the advice *smh*

I call my buddy a road warrior since he quit doing 1/4 mile racing and bought fancy cars for road course stuff... :P
I am a Point A to Point B racer

Originally Posted by ImNowTylerTibbets

Who built the intake on the northstar?

I know that westcoastfieros and some others of the fiero cult have done engine/transmission swaps and combinations that would blow most peoples minds on this forum.......

LOL take for example people said a 4t80 wouldn't work..... But it does.

said a LS4 would not work with a 4t80..... but it does.

If you want to stop the negativity and non believers then post up results.

If its anything other than a SC or turbo 3800 with a junk 4t6fail glass transmission mated to it its crazy talk here........ LOL.

Me personally I still think the pulsing is a bit overkill for a 3800. Now stick it on a different engine that's capable of using higher RPM then it may be a different story such as a northstar engine or 3.4 DOHC engine. DOHC engines have entirely different power bands to begin with.

4t80e "works" ... but not very well ... for any powerful setup.. it still blows up. Just in different spots.
As far as I can tell.. anyone whos been running them, blow the crap out of em. If kept power down it'd probably
last, but then what would be the purpose of the swap then. To me until someone can go a full race season without it
doing a self destruct sequence, I am sticking with the 65fail.... at least some aftermarket is alive for it...

Im working on it... ass

Originally Posted by Turbocharged400sbc

Im working on it... ass

Since like what.. 2002?

By time you get it figured out, warp drive will be a common thing.

Originally Posted by SgtMarshal

the LS4 4T80 swap that furches performance built wouldn't do a 2-3 shift, and ended up blowing a big hole through the LS4 block. there is one example of a 4T80 swap not working. as far as I know, the 2/3 shift is the biggest problem of the 4T80.

Ben smashed through a few on his twin engine setup. His EP build didn't last long either.
He's got far on his last try, but one of his mods, required to weld a huge tank on the side of it to hold a ton more fluid.
Wouldn't work on our cars cause the frame is in the way.

Either way, 80e to me is still a bust. Unless you want to stay maybe the 4xx whp land maybe. And booooo on that idea.

my issue is with a divided T4 with a giant AR on a small displacement v6 with a rotating assembly thats better for making power down low/mid range rpm.
i have a feeling your leaving a ton of under the curve performance off your car.

i doubt its a divided T3, which at least the area of the one port is just a hair bigger cross sectional area as one exhaust port.
a divided T4 has each port a good bit bigger than each of our intake ports. no mater what you do with the piping that increase in cross sectional area is creating a pressure drop as it enters the turbine scroll. sorta not what the pulse tuning is about, kinda hard to keep that pressure wave energy moving when the area of the pipe increases as much as it does

and since pulse tuning is to help at low/mid range Rpm's by spooling the turbo....youd probably make way more power at the bottom half of your curve if you kept the exhaust gas velocity up...

Ok I will bite: This is an assumption and also lets preface; you said “my issue”…this is 231ci on a 6-cylinder it is relative. For me it is a big v6…irregardless my philosophy is to always leave power on the table. Many ppl will learn well from this small principle…I have FWD and a RWD, I am not deluded into thinking I can make one like the other and the type of racing I do…each one brings its own strengths. Power on the table is fine for me. You are assuming many things, how do you know I have a T4 or T3…did you ask? Or you just want to tell me about Turbine theory?


Edit: for reference only (I was emailed); this was my setup in late '97



the current exhaust manifold look similar to this done in about '05



…I think you are simply nitpicking here; this is why the principles behind good turbo exhaust manifold still holds…high pressure, high heat including high velocity…this “package” must be delivered to the turbine as quickly and as efficient as possible…period!! Now efficiency is unfortunately interpreted differently; not to go on a meaningless tangent. Efficiency for me takes the point of what type of turbocharging application you care to employ and then apply them accordingly (I am talking system approach)…I know in reality this depends on packaging, marketing, space constraints etc, etc…we can both agree HOWEVER that bends reduces efficiency of the exhaust gas, so does length and sizing…especially for an engine that does not naturally RPM (high rev)… however your analysis of throat area (if this is what you are alluding to)of the exhaust valves and throat area of the turbine does not make sense…

the people complaining about the 4t80 fail to mention that bens twin engine car and the ls4 turbo 4t80 were both setups north of 600hp.......

just saying......

it takes an absurd amount of money and unobtanuim gmr parts to get a 4t6fail glass trans to be able to stand 450 plus let alone 600.......

4t6fail cost vs 4t80 cost the 4t80 wins all day every day..... hell you can buy a damn 4t80 for the cost of just the 7/8s upgraded chain never mind the unobatnium gmr 1 inch price of over a grand thats at least 2-3 4t80s for that kind of money.......

the shifts are worked out people have done them the hardest part is making them fit........

no one has put a fresh 4t80 with around 500hp in a wbody. Around that hp level and a fresh trans id expect it to live for quite a while.

especially in a light gutted car like my caged car or a fiero.

Lol new guy 16 post kornhead since 2013........... OWNED.

i should warn this forum frequently requires the use of tylenol or advil potential for overdoes is strong here......

lololololololol

From my gathering headers produce higher horsepower at the top end, but you loose a few hundred rpm in spool time. HP gain would be worth it to me.

Most turbo guys here run the log type, some run the cast manifolds. I have a front log and rear cast.

We are all a far cry from 1000whp

ZZP's car runs turbo headers and is/was over 800whp

I have seen alot of the ls guys run the cast mani to the sky and beyond, lucky guys.

I used ZZP Plogs on my setup... Seemed to hold up pretty well. Before I took the car down for never ending upgrades, they didn't seem to really be a big bottle neck problem.