The Fugitive

iTrader: (6)

why not just do a 370, a Frost dual pcm/ecu, o-ring the block or heads and boost the **** outta it and keep a second tune for the street?

leave the diablo alone unless you have to drive a good distance for a tune. buy hptuners or the like if you go that route. The tunes(diable/sts) that they give are not really made to get out there and have a lead foot, they are safe general tunes that really can't take into account all the conditions that are made from a custom tune. A wideband is always a smart choice don't forget to get one.

longrange4u

iTrader: (2)

Figured sense I said something about the LT's and not the rest of your questions I would loop back..

#1 Min upgrade to a new Walbro 255... that will handle what you are doing (if you stay at 8lbs and NO MORE).

#2 Save your money... get it tuned by a good shop that knows what they are doing. Do it for 8lbs of boost and you will be good.

#3 I wanna add some reccomendations (and echo some of what the other folks have said)..

- Buy an intercooler kit.. in my opinion... this is a must!
- wrap your exhaust from your exhaust manifold to the turbo (get rid of the LT's).... this will GREATLY improve your performance.
- spend $300 bucks and buy a set of truck heads (6.0L truck heads) and put them on... that will drop your CR by a point. (Great saftey for your engine)
- reccomend 42# injectors min... if you think you will EVER go above 8lbs (10-12) then start with 60# high imp injectors. You can get a gooooooood tune that keeps your fuel ratio VERY safe... you could run 10lbs all day (with the above mods)

So... to answer #3 With the above mods I reccomended, and a mild cam, I put 585RWHP down at 10lbs through my STS.

WARNING... I then went to the track.. ran an 11.01 1/4... was so excited, turned it up ~1-1.5 lbs to get that "10 sec run"... blew up my #7 piston.

If I had 60# injectors and a better tune for them... I would have been ok. But I ran on 42#'s... with a tune for 9lbs.. and

Now I am hooked... and in the next two months I will (WILL!!!) run the first 8sec run in a rear-mount F-body.. oh.. and nothing is STS on my car anymore.

mike13

iTrader: (27)

lot's of good info from longrange4u, buy the 60lber's that why your only buying injectors once, car will run fine on 60's even if your not boosting. I would run a intercooler for sure and also methanol injection especially if you stay with the stock compression. The few guys I have talked to who have made stock motors last all run conservative AFR's, timing and ramped up methanol injection. What horsepower they loose thru a conservative tune they gain by running a little more boost.

The Fugitive

iTrader: (6)

have you ever posted pictures of your set up?

ZL1Killa

iTrader: (17)

+1

check out my thread.

longrange4u

iTrader: (2)

Yep! Haha... I will do another build thread soon.

eodmonkey

the 383 was an easy kit for me to get forged. right now i think i'd be good with 10-15psi. if she runs well enough at 15 i may do a boost controller and bring it down for the street. 9's are fun but i'm working on a wrangler too. so i can have something i can use with back seats

dwfronk

so nobody has answered the question of shorties.

My theory is they are short so less heat loss but still flow good.

hawk584

iTrader: (1)

in my humble opinion a smaller diameter pipe will create a higher velocity of flow compared to a larger diameter pipe with a power source who's output is the same.... but what do i know, my screen name isn't the all mighty zombie

Zombie

iTrader: (2)

Flow and velocity don't seem to matter much due to the turbo's exhaust housing being the biggest restriction in the exhaust. Keeping as much heat in so you can have the waste gate open and run the largest turbine wheel and a/r housing will cause the entire exhaust system to flow more.

Keeping heat in is the key, all the velocity is created from the turbine housing.

eodmonkey

so maybe someone can point me to the thread but doesnt heat have no effect on a compressor other than make it hot? airflow either hot or cold will spin your wheel, trim determines how much velocity it takes to spin. larger piping slows exhaust velocity(pressure), more air in more air out. i kinda get thermal expansion but thats on a static system how much of an effect does it have on a gas in motion and at what point does it just not matter and you start to look into either your air turbulence to increase flow or just increase your volume of air from the engine?

hawk584

iTrader: (1)

.yes, cold or hot will spin the turbine,... heat expands gases. smaller tubing (to me) flows those gases faster... larger the tubing = more surface area for heat loss...heat wrap to keep heat in, smaller tubing induce faster flow & retains more heat.. hotter the exhaust, pipe size = faster velocity...


...never mind, others say i don't know anything about r.m. turbo's so i shouldn't say anything about them... refer to zombie, he's the god of rearmounts and is in the 10sec. club

longrange4u

iTrader: (2)

Wow.. there seems to be a little aggression towards Zombie by folks. Doesn't make sense to me as he has spent allot of time sharing his experiences.

Well... sense I am in the 9 sec club I guess I owe some input. I was the first rear-mount fbody in the 9's... and will be the first in the 8's in the next couple months. Oh and Zombie was allot of help with my decisions and build direction. (Thanks Jeremy!)

It is not about velocity as a turbo is a resistance mechanism in the line and isnt greatly effected by the speed of the air, rather the volume.

So try to imagine it this way... if we agree that we are going to push water down a 3" pipe at a fixed speed (an engine produces a fixed amount of exhaust)... at the end of the pipe you put a restrictor.

How fast the water gets from one end of the tube to the other isnt as important as the relative pressure achieved when the water arrives.

Test one: If in one version of the experiment I try to pass 10 gallons of water down the pipe at the fixed rate of entry (fixed speed in which I add water) of 10 seconds, one pipe is straight and one is twisted repeatedly.... logic would insist that the straight one would far outweigh the curvy one. However... because of the restriction, water backs up at a near identical rate due to the limitation of the volume of water that can pass that restriction.

Test two: Same as one, except this time I will push 10 gallons down one pipe in 10 seconds, and 20 gallons down the other in the same 10 seconds. On the second pipe, relative pressure will be doubled thus the amount of water pressure at the point of restriction will go up significantly.

Now lets apply that to turbos and exhaust. The temperature of air effects the density of air. Cooler air is more dense, and hotter air is less dense. This means that Cooler air has LESS volume than hotter air. (Note the important thing to take from this is that Hot air has significantly more volume then the same amount of colder air)

As we discussed above.... keeping our exhaust temps hot all the way to the turbo gives us more pressure at the turbo (thus faster spool). This is the desired effect! We cant make our engine produce more exhaust, but we want to maximize the efficiency of the turbos use of the exhaust gas. Or, we want the most volume we can cram down our turbo to get it to spool faster...


LT's reduce the resistance (back pressure) of an engine to allow for more efficient production of HP. However they have something like 7-10x the surface area of manifolds, thus accelerating the cooling process of the air. As we dont care about the reduction of resistance as much in a turbo setup because that is largely dictated by the AR of the turbo, not the exhaust type.

Short tubes... same problem, just a little smaller.

Hope this helps some... ask questions and I will refine this more.

eodmonkey

ok so, lets say your engine flows x at the heads. has anyone seen what the difference in flow is down the line? the gas has already expanded in the chamber, so your not getting that volume any hotter and its not expanding anymore. maybe i'm skeptical of this whole it must be hot approach, but does anyone know what the drop is by the time it reaches the turbo? sure heat expands molecules but they're already expanded now your just moving that volume down the line at a high rate of speed.

eodmonkey

nice timing, you posted as i was writing mine

mike13

iTrader: (27)

Can you ceramic coat a set of headers either shorties or long tubes and have them be comparable to a seat of manifolds?

Zombie

iTrader: (2)

Nope, it's been tried and failed. Haven't seen any back to back comparisons on shorties though, but I don't think they'll make any more power than a manifold under boost because of back pressure. They do have more surface area than manifolds.

A hotter gas has more energy. The hotter the gas, the less of it you need to do a given amount of work (such as spinning a turbo) which leaves more gas to be bypassed through the waste gate, turbine and housing which nets lower back pressure and higher efficiency.

hawk584, you have some issues.

hawk584

iTrader: (1)

i'm not angry with him, nothing i say is useful and i'm frustrated that my car has been on jack stands since mid Feb. and i can't find the problem... sorry Z

mike13

iTrader: (27)

I have 383 (LS1) ported 317's 224/230 cam , auto, rearmount TC76 w/.96 a/r. Just installed the 383 should I go with a 1.15 a/r or buy a bigger turbo? My goal is 750rwhp

longrange4u

iTrader: (2)

I would think you will be close to your goals as you sit... Zombie and 1320 have done alot of experiments with AR's on rear-mounts. I think that will affect your spool time but not as much your HP numbers. But I am not an expert on the AR ration effect..