I been looking all over the internet for a stainless steel Y pipe and have not been successful. I need it to be 2 1/2 inch dual in to 3 1/2 inch single out. I am not interested in a steel one. If you can steer me in the right direction I would appreciate it.

 

Are you just looking for the merge or are you looking for the complete y-pipe? If it's the complete pipe, what headers are you running?

 

I'm just looking to merge the two pipes right before the cat. SLP headers 1 3/4 inch size at the heads which then bolt to the current 2 1/2 dual pipes. 1 pipe runs past the oil pan which comes right next to and runs paraell to the pipe coming from the passenger side. At that point the current Y pipe installed from the last owner necks down to 3 in. This 3 inch exhaust I believe is currently the major limitation in my horsepower right now. Car dyno at 370 hp. Which seems low for a 383 with 9.5 to 1 compression, 58mm throttle body, TPIS intake Trick Flow heads, 231 intake 239 exhaust @ 50 BUT this is my first hot rod car I've ever done so I'm not 100% certain this is the problem. O its a slip fit with those thin band clamps on the Y pipe on both sides.

 

http://www.autoanything.com/exhausts...A2680A0A0.aspx

dont know if they make a 3 1/2 you can take a look

have you had to car to the tack?

any 1/4 times?

 

The Magnaflow is pretty restrictive. If you have access to a good MIG with gas (not the WalMart specials using flux core schit wire like everyone on here does) it's pretty easy to build. I bought the mandrel bent pipes and built my own when I built my 409 SS 2.5" y-pipe for my SLP headers. Actually built 2 and used only one but it's only 3". You really don't need anything bigger. My old 406 setup without the F1R was pushing a lot more than your 370hp and I was running 3".

FYI, my car is the Firebird on the Mufflex website with the 4" system. The car lost power with that schit system. It wasn't on the car long before I went back to the 3" Flowmaster I was running before.

 

I my self. Dumped the Flowmaster Y to small.
but thats when i was running 200Hp Hit of NOS. (10.30's)
just not enof flow out of that 2 1/2 on
the SLP ss headers.. also getting dumped.. (thats on the old 383)

picked up the 2210 Hookers CC and 3"CutOuts on ea side..(for the track)
for the New 427. and intercooled Procharger.

 

Yes been to track I'm running 13.6. 3.70 gears 2500 stall I have no hook up problems cause i'm running drag radials.

 

1/2" is not going to do much if anything..
what muffler is on the car.

hows the car shifting..what RPM

 

You're looking for something like this, right? This one is dual 2 1/2" into 3" 409SS





or are you looking for something like this?

 

Are you running mid 13s with a 383 stroker? What is your trap speed? 105-107 I am guessing?

If you are looking at why it isn't performing the way it should, I would start someplace other than the exhaust unless its completely stock..

 

The first picture 96BlownSSragtop has is what i'm looking for. My current setup looks like the last picture, but instead of the single 3 inch pipe I want to go to a 3 1/2 pipe. Hoping I can slip my old y pipe off and slip in the new one.

 

Yes its a 383 stroker with 6 inch rods 1.6 ratio rockers. The muffler is Flowmaster no clue which model it is. It was on the car when I bought it. The cat is 3 inch from Catgo. The car shifts fine. My shift point is 6000 rpm well at least the light goes on then I normally hit it at 6100 ;P ;P ;P the trap speed i think was 102 106 range not 100% sure have to find slips. The only other thing I can think of thats causing a restriction is that old cold air intake pipe its very convoluted accordion shape necks down to 2 1/4 inches and makes that 90 deg turn that has baffles inside it.

 

I hate to be THAT guy but did YOU build (or have someone build) the motor? Or is that what the previous owner said was done? 13.6 seems "slow" for what you have done. Like stated, I don't think the 1/2" of piping is going to cure it and at 370rwhp, you should be in the 12's easily. It sounds like there are some other things that might need addressed if you want to go faster. You also could always get a 3" y-pipe and cut/weld on a 3.5" piece. I've seen the 4" outlets and 3" but haven't came across a 3.5 that is stainless.

 

Also, not sure what kind of tune you have in the car, suspension, weight etc but if your looking for faster, you could do without swapping to a bigger exhaust for your particular car. Sweet sounding setup you have there though

 

As far as the motor goes it was built as a short block by a company I never heard of before. I know all the parts that are in the motor because the previous owner keep excellent records he had every receipt and my god did he spend a lot. (The only missing receipt is what valve springs are installed) When I changed the computer The tuning was done by Euro Trick Tune for lack of knowing a better place to bring it to in MO. The runs where done on open loop control the AFR stayed between 12 to 13 the whole time. The computer is from Painless Wiring (DON'T buy it it sucks had to keep calling them and getting software patches just to get the damn thing to work and that wiring harness wouldn't even come close fitting correctly if my motor was 100% stock) As far as the weight goes its probably 200 to 300 lbs lighter than stock. The suspension well it has Hotchkis subframe connectors welded in. All the bars in the rear are Hotchkis also, except the torque arm which is stock. The shocks are Gabriel and the springs are stock. I really don't think its any type of lunching problem. I had my buddy watch the lunch of the car the tires don't spin and there is no suspension hop. O I'm not sure if I trust Euro Trick tune statement of the 370 HP I wasn't there when they did it.

 

the only thing i can think of is.. do you have the 1000cfm TB(twin 58mm)
and 30lb hr injtrs (for a 383 like your's.. you should have them)

have done a 383 sorta like yours (close)
and with 3500 lb car 4.10 gears 12.60's

 

It a 58mm Summit brand TB. It says they are 1000cfm. I originally had 30lbs injectors on there but Euro Trick tune said they where too big and installed 25lbs injectors.

 

make sure it's twin 58mm =1000cfm
(not just a 1000cfm name plate)

and try this.. up your fuel presher 2 to 3 LBS and see if the car speeds up or slows down in the 1/4 mile

install a presher guage on the fuel rail tape it to your window.. see if it't drops at WOT.
also

never used anything smaller then a 30 LB injectr on any of my 383's
even Linginfelter told me that..if you want all the power it will make amyway. for street driving...less then 30's will work but will less power.

GOING 2 TO 3 LBS more fuel presh will tell you if it needs more fuel
at WOT.. but then this is with a lingenfelter 383 eng (my old one)
it sould be the same for yours

 

Well I can't really take it to the track right now its winter. I have the fuel pressure set to 50 psi it drops to 48 psi at WOT. I'm not sure if that 2 psi drop is normal for WOT. Its the twin 58mm throttle body. The car has the stock fuel pump. Do I need to go bigger?

 

expl:

my 383 fuel presher is set at 52psi with 30LB injtrs pulls hard to 6100rpm

i up the Presher to 54/55 the car drops 1 to 2 tenths in the 1/4 mile

i drop down to 50 and it stops pulling at about 5800rpm

 

O! really thats interesting didn't think it would affect it that much. Does the pressure change at all at WOT for you on your car. Heck if this solves my problem I'll get my 750 dollar pressure gauge from work and set that pressure!!!!

 

mine stays / shakes at 51psi at WOT.

Hypertech has a good Guage for the $50 ball park just screw it on tape it to the window and Go..

checking with a fast look all 3 guages at right will point strait Up.when OK.

 

ok this explains a lot the regulator is actually getting starved or the regulator port is too small. I wasn't sure if it was regulator droop since car fuel regulators are basically direct acting regulators with a vacuums line to help suppress droop (though I'm not sure how much it suppresses). I was thrown a little bit because industrial regulators don't use a vacuum line to suppress droop it would kind of defeat the whole purpose of having a regulator over a control valve. The other thing that threw me is one of the manuals stated to set fuel pressure between 48 to 50 with kind of range accuracy didn't seem that important. I think i'll skip the exhaust for now fix the fuel and I'm going to experiment with the air intake filter/box because thats cheap to do. thank you for your time and knowledge. O and that blood red interior looks nice matched with that black.

 

If it IS the stock fuel pump, I would change that for sure. Could explain the pressure drop, pump might not be able to keep up (I would bet on it if it IS a stock pump) therefore starving your regulator/lines. I'd upgrade the pump for sure if it was me. I'm running the Racetronix kit with the upgraded wiring harness etc. Provides constant voltage, heavier gauge wire, has an output to add a "booster" to increase voltage (which would increase output of the pump). I've got the 255lph Walbro high pressure pump. Upgrade on injectors would also be good in my book. Stock injectors are around 22lbs on a Corvette L98, so 25lb is only a slight upgrade. The vette guys run 25lbs injectors on stock engines with a mild cam and some computer tuning. Your WAY beyond that

 

I am going to go ahead and say someone lied to you a long the way. I trapped almost 97mph in my full weight car with less than 230rwhp because the car was on 7 cylinders. Even 107mph isn't indicative of anywhere close to 370rwhp. A friend of mine went 110 in a bolt on ls1 auto car. I used to have it on film and I helped him install every part on the car.

What heads, cam and intake are on the car? 25lbs injectors are barely bigger than stock L98 injectors. What exhaust is on the car? Do you have any way to verify that the air fuel ratio is good? Not just one of those crappy autometer gauges but an actual wideband with quality gauge? How much timing are you running? What about compression ratio?

I think for now you really need to figure out what your engine setup is and figure out what's causing the poor performance. IMO if its a properly built 383 you are about 2 maybe 2 and half seconds and a good 10-15mph too slow. Start with figuring out why it runs the way it does before you start upgrading parts.

 

Its an AFX wide-band monitor. The calculated compression ratio is 9.5 to 1. I mentioned the cam and other things in my previous posts. ANYWAY I've been taking apart the car for body restoration including the engine bay. I have found a discrepancy in what cam is installed and what the receipt I have. The cam is actually a Lunati 60112 not a Lunati 60122. The real cam spec is 219 intake 227 exh @ 50 with 110 lobe separation. I'm a bit pissed at myself because I installed that cam and didn't check the grind numbers on it before I installed it. He had even a smaller cam in it when I bought it. He changed it out to try and get the computer to run the engine right again after making it a 383. I know him he is 100% computer illiterate. He doesn't own one nor has he ever turned one on. ONE thing has me a bit worried when i bought this car had a stock computer with stock chip....well I found a drag slip in the car very old though 6 years ago (but the car sat for 5 years in a garage unused) one lane was in the 10's but the other was 13.2 which i assume is my car (I know this one never ran 10's). So basically after I changed the computer over to Painless Performance and had it tuned by Euro Trick the car slowed to 13.6 Currently the intake has heavy carbon build up to the throttle body vanes after only 4100 miles of use. It didn't when i got the car cause I shined a flash light into the throttle body right after i got the car and when I took the intake off it was pretty clean. I think I may have got a crap tune or it was tuned with a bad O2 sensor. I sent the car to them with 30 lbs injectors and the replaced the to 25 lbs. EVERYBODY here is telling me I should have 30lbs ones. O the cat isn't clogged I feared it might be but the brick is missing. I guess the previous owner knocked it out. In MO the cat has to be installed to pass MECHANICAL inspection but the car doesn't have to do emissions because MO doesn't look at pre OBD 2 cars for that. So cat clogging is not an issue.

 

Not having enough fuel could cause it to run poor like it does as well as a bad tune could cause the same. You installed the cam so that's good, you should be able to tell the trick flow heads pretty obviously, the only part that would be hard to check would be if it IS a 383 or not. Could be a stock shortblock, but even then, a 350 with those heads/cam should be faster. I'd look at changing the pump, injectors and take it somewhere that can tune GOOD. A good tune can make a world of difference even in a stock car. It was amazing to see how much difference a small GOOD tune made to my buddies 98' TA after all his bolt ons (long tubes, gears, no cats, loud mouth exhaust, pullies, etc). He was running high 13's after everything and rich as hell. After the tune he dipped into the 12's no problem on street tires. Another friend of mine with a 94' Z28 did an LT4 hot cam in a stock LT1, pacesetter longtubes, no cat, exhaust, and converter with stock 3.42's and hit 12.99 on Kumho's. I'd say your build should be much faster than his.

 

Pretty sure its a 383 its got those notches cut into the block down by the oil pan for the H beam rods that are installed. Don't see why someone would go thru the trouble having a machine shop to do that then build it as a 350.

 

Understandable. I believe it is with all the other stuff on it, but that makes your fuel issue look like the culprit even more.

 

Well motor pulled heads taken off and I'm depressed. The car had been running too rich carbon build is extra thick. That wouldn't be so bad thats all fairly easy and not super expensive to fix. Then I saw cylinder 4. Just 1 big long scratch so deep I can stick my finger nail into it. Pulled the pistons and number 4 piston has a small piece of its ring missing. In fact I can see a small piece of a different color metal imbedded into the aluminum piston along the side. Yada Yada the car is going to be sitting for awhile.

 

That could explain the poor 1/4 mile times then. Sucks to hear bro, good luck with it though, I'm sure you'll get it back up and running good! just clean the rest of the motor up, get a new piston and rings and go to town!