The basics (and the not-so-basics) of turbocharging...

[professor_speed]

  I have heard a guy who I would consider to be a genius, state that the majority of charge piping is sized larger than necessary, which they claimed induced extra lag (as well as cost and under-hood real estate). I'm pretty sure this guy was an engineer for turbofans, or something along those lines.
  On the other hand, LSx motors have a relatively enormous displacement compared to the M50/S50 series of motors (but those motors do have excellent flow with the stock heads, DOHC/4-valve, etc.). The impression I got was that you almost never need more than 2.5", maybe 3" for charge pipes, but that most people do not want to listen to this.
  For post-turbine-outlet, I have never heard anything but bigger is always better, velocity doesn't matter, etc.

I don't know what a m50/s50 is but we are dealing with a large V8 that in turbo form makes big power so your 3 inch pipe theory goes out the door, its all based on how fast the air will have to move in the pipe to  get the mass air flow rate need to make power. at 1000hp the air is moving at ridiculous speed (especially before the turbo) in a 3 inch tube, turbulence  will cause a pressure drop. can it be done yes is it ideal? NO what ever pipe size people are using for na intakes are what would be ideal for charge pipes (not always possible) remember when turbo charged you are moving the same volume of air (after the turbo) but you have increased its mass

[professor_speed]

My $.02 on the billet thing.

Is billet better? Depends on the wheel, precisions 62 ans 67 are kicking ass but, those were two of the most out dated wheels out there, so it should have been easy to improve on. now the 72/76/78 wheel is a lot newer design, so the billet counterparts don't seem to be making an improvement. yes you can get more blade area by using a smaller hub with billet, but think about  the actual amount of air the blade moves at the hub. yes the blade area has increased but at the most worthless part of the wheel, and the area that it has increased is very small, not even close to what happens when diameter is increased

as far strength goes lets think logically, cast wheels go to 106mm (2400hp) think of the forces on that wheel vs. a 67-88mm wheel most of us use. if it works there in cast our little cast wheels will do just fine.

on a side note when I talked to tnetics, precision, and garret they all said the  place they can claim gains are in high pressure ratio applications

On another side note Allied Signal bought Honey Well but kept the Honey Well name.

[spacevomit]

  I have heard a guy who I would consider to be a genius, state that the majority of charge piping is sized larger than necessary, which they claimed induced extra lag (as well as cost and under-hood real estate). I'm pretty sure this guy was an engineer for turbofans, or something along those lines.
  On the other hand, LSx motors have a relatively enormous displacement compared to the M50/S50 series of motors (but those motors do have excellent flow with the stock heads, DOHC/4-valve, etc.). The impression I got was that you almost never need more than 2.5", maybe 3" for charge pipes, but that most people do not want to listen to this.
  For post-turbine-outlet, I have never heard anything but bigger is always better, velocity doesn't matter, etc.

I don't know what a m50/s50 is but we are dealing with a large V8 that in turbo form makes big power so your 3 inch pipe theory goes out the door, its all based on how fast the air will have to move in the pipe to  get the mass air flow rate need to make power. at 1000hp the air is moving at ridiculous speed (especially before the turbo) in a 3 inch tube, turbulence  will cause a pressure drop. can it be done yes is it ideal? NO what ever pipe size people are using for na intakes are what would be ideal for charge pipes (not always possible) remember when turbo charged you are moving the same volume of air (after the turbo) but you have increased its mass

That makes sense. M50/S50 are 2.5-3.2 liter BMW I6. If you read what I wrote, it wasn't my theory (although I did find it compelling). I feel silly having just stated that I read somebody's opinion, and here is what it is, but I did state that openly. The statement "you almost never need more than 2.5"-3"" probably doesn't apply to a large turbo V8, but I just thought it was interesting, because most people would think there is no such thing as too big (Mk.4 Supra community).

[Copper280z]

m=(A*V)/v and P*v=R*T

These are the equations you need to figure out how fast the air is flowing in a simple pipe, m is the mass flow rate, A is the area of the pipe, v is the specific volume, P is absolute pressure, R is the gas constant of air(53.3533), T is temperature in Rankine.

Lets assume that we make 1000hp at 20psi of boost with IAT's of 150*F(610*R)

v=(53.3533*610)/(144*(20+14.7)) - the 144 is to correct the units from in^2 to ft^2
v=6.513 (ft^3/lb)


m is roughly 100lb/min and a 3" pipe ha 7.06 in^2, so

V=(6.513*100)/(7.06/144)
V= 13284 (ft/min)

convert that to ft/sec and we get

V=13284/60
V=221.405 (ft/sec)

or, about .2 mach(5 times less than the speed of sound)

Not actually sure what this means, fluid dynaimcs is next semester, so if you wait about 6 months I can tell you. lol I do know that I've heard people claim that <.3 mach is good in a cylinder head port, so it sounds a little bit high for piping. As an educated guess, I'd say that you need no more than 3.5" piping at 1000hp, and about 3" at 750hp.

[MPbdy]

Haha good luck with fluids.  Have you gotten to intermediate dynamics yet?  If I can ever get into those I need to take them too..

Interesting thread, keep it goin

[383mazda]

A side note for the rear mounts...  At work we hooked a 1200 degree pyro up to a silverado with a rear mount set up.  6.0L engine with a 76 turbo, the pyro was about 2 inches before the turbine, it didn't take long for the gauge to get maxed out after we floored it.  The exhaust back pressure ratio was right around 2:1.    We also have a C6 with APS turbos that's being tuned and on the local dyno our STS car spooled up quicker and made more power... not a ton more or anything, but more nonetheless.

I think with this type of topic "lag" and boost threshold hold get used interchangeably when they shouldn't, as they are two different things.  Yes a rear mount, or a front mount with a liquid intercooler in the pass seat will have more lag than a traditional FM setup, but both are going to be extremely short (under a second I'd bet).

That was just my two cents, I don't want to turn this into FM vs RM thread, I just want everyone to know that turbos are always a better choice than supercharging!!! 

[ImportEvolution]

funny how garrett downplayed billets for the last couple years and now they've released a new series of billets.  I think in the 30r, 35r, 40r sizes

[frijolee]

Ok, since we're talking basics here, what's a rough budget per horsepower calculation and what kind of HP levels drive you do what kind of system modifications.  Please break out costs as much as you can so folks can compensate for doing work themselves, upgrades they already have etc...

Example, let's say I want to target 750 rwhp.  I'm guessing I need a forged bottom end but otherwise can stick with my existing ls1 block and it should still be pretty stable.  I'll need an upgraded driveline but can still get away with 4 bolt OEM heads and the OEM intake manifold.

-Piping w/ self fabrication $1,500
-FMIC $300
-Boost control (3 bar maf, wastegates, controler, pop-offs) $600
-Decent single turbo $1,000
-Fuel managment (X pump, Y lines, Z injectors) $700
-Cam, springs, retainers, pushrods $600
-Forged pistons and rods (but not crank) $800
-ARP bolts (head and con rod) $300
-Serious radiator, fan and cooling misc $600
-Ford 8.8 rear end $3,000
-Tuning $600

That puts my guess at a budget around 10k.   Is that about right for 750 hp?  What could I do to simpfy if I wanted to stay stock internals, what kind of HP is reasonably safe to shoot for?  How big a jump up is it to make 1000 hp?

[Andrew R]

Ok, since we're talking basics here, what's a rough budget per horsepower calculation and what kind of HP levels drive you do what kind of system modifications.  Please break out costs as much as you can so folks can compensate for doing work themselves, upgrades they already have etc...

Example, let's say I want to target 750 rwhp.  I'm guessing I need a forged bottom end but otherwise can stick with my existing ls1 block and it should still be pretty stable.  I'll need an upgraded driveline but can still get away with 4 bolt OEM heads and the OEM intake manifold.

-Piping w/ self fabrication $1,500
-FMIC $300
-Boost control (3 bar maf, wastegates, controler, pop-offs) $600
-Decent single turbo $1,000
-Fuel managment (X pump, Y lines, Z injectors) $700
-Cam, springs, retainers, pushrods $600
-Forged pistons and rods (but not crank) $800
-ARP bolts (head and con rod) $300
-Serious radiator, fan and cooling misc $600
-Ford 8.8 rear end $3,000
-Tuning $600

That puts my guess at a budget around 10k.   Is that about right for 750 hp?  What could I do to simpfy if I wanted to stay stock internals, what kind of HP is reasonably safe to shoot for?  How big a jump up is it to make 1000 hp?

I have seen 5psi blower cars lay down 500+rwhp for years on stock internals without major issues -I guess at the end of the day it's going to be how your drive maintain it.  I personally would run the stock internals and build everything else with some headroom to expand on one you build the engine. You should be able to easily get 600+ rwhp on low boost

cue Tracy -where is he...   or Nick 

[BeasTT]

Meh, you're kinda close. There are a lot of variables so it's hard to say X dollars for X horsepower. As for stock bottom end cars, 500-600whp is average. There is a sticky on this topic on tech http://www.ls1tech.com/forums/forced-induction/1056169-stock-bottom-boost-reliability-list.html Driving style and tune are going to be the 2 biggest things that determine stock bottom end longevity. IE some one who tuned the car themselves and bangs gears stop light to stop light is going to break something and bitch about it, where as someone who has their car tuned and romps on it occasionally or when "needed" is going to get a lot of miles out of the setup, This is pretty obvious, but I feel it's note worthy


I know you just kinda guessed on prices, but going off what you listed here;s what I'd say

-Piping w/ self fabrication - I have $500 in my turbo headers and shouldn't have more than $250 in down pipes and cold side piping and $100 in tbolt clamps and couplers.

-FMIC $250-300

-Boost control
- 3 bar map - $50
- wastegates $250 each
- EBC $200(truboost)-$1000(AMS1000)
- BOV $150-200

-Decent single turbo $800-1,200

-Fuel pump - 2 044's @~$200 each

AN braided lines - $500-700

80# injectors - $400

-Cam, springs, retainers, pushrods $600

-Forged pistons and rods (but not crank) $800 plus machine work plus bearings plus gaskets plus assembly if you cant do it yourself

-ARP head studs - $300

-Mishimoto radiator, taurus fan and cooling misc $500

-Ford 8.8 rear end $2,000

-Tuning $600

That's a start. I'd also do an oil pump, clutch, shift keys, shift pads, shift fork, and if it were my car, I would go sumped tank with a single a1000 or Magnafuel 4303 since I doubt you'll be hitting 750whp on 93

FWIW I have just off top of my head over $15k in my power/drivetrain and I should clear 1000rwhp on c16. And I did it the cheapest way while still being reliable

[digitalsolo]

My method:

Forged motor w/ stock crank and ARP hardware, good springs, LS9 cam, good springs, stainless valves:   $3000
Turbo:  $1000
Wastegate:  $400
C6 manifolds:  $75
Pipes/flanges:   $400 (mild) or $800 (stainless)
Vacuum hoses, misc. plumbing:   $100
Boost gauge/controller:  $100
Intercooler, cold side pipes, couplers/clamps:  $350
BOV:  $150
Fuel parts (dual 044 or Densos, -8 feed, -6 return, aftermarket rails to put regulator after the rails, boost referenced FPR):  $800
Injectors (80# Siemens):   $350
2 Bar MAP:  $50
OS for PCM:  $100

That's just shy of $7000, and personally, I'd have some good heads and an LS6 or other good intake as well in the mix.

That would get you rolling.     There's lot of other stuff I'd do, like a better boost controller, ceramic coating, yada yada, that adds up really quickly also.

[frijolee]

http://www.ls1tech.com/forums/forced-induction/1056169-stock-bottom-boost-reliability-list.html

Good link, thanks for sharing...  I'm surprized how low HP wise a lot of these failed.  Plenty of carnage in the 550 rwhp range.  Makes me wish there was something similar with the addition of forged rods/pistons.

[BeasTT]

Forged rods and pistons will cross the 1000rwhp barrier with ease. At that point the stock deck width of the 4 bolt heads becomes the weak link on an iron block, and the same plus cap walk become the weak links on an aluminum block.

I'd like to know how many of those blocks that failed were running the LS6 block of plates in the rear.

[frijolee]

Going to all the trouble of doing a turbo setup with a stock bottom end seems to me like you spend 90% of the effort to see a 200 hp bump (350->550), where had you done just a little bit more, doubling that gain would be very attainable...

What's a reasonable boost level if you want to stick to pump gas?  (Meaning 91 in the case of we poor Californians)...

By block off plates do you mean the ls6 steam tube plugs?  Sure seemed like lots of #7 piston failures...

[largeorangefont]

I think generally people who turbo stock block cars do it because it is easier/cheaper to turbo the car than to rebuild the engine, and you get more bang for the buck.

The problem (generally) with those type of people is that they don't know how to tune, or take it to the cheapest tuner who tries to get too much out of the setup. I can't tell you how many people I deal with that try to run 12:1 AFRs or MBT timing, or both on a boosted car with crappy gas. Very few of the forced induction V8 people (Ford and Chevy guys) monitor EGTs, which is the root cause of the majority of piston related problems.

The "back" cylinders run hot on just about every engine out there. For LS engines having the steam tubes in the back may help a coolant circulation a bit, but it is not enough to compensate for a bad tune. Fuel is what cools the pistons, not water.