sparkwirez06

iTrader: (18)

I have changed my combo I am limited to a 3" dp without more mods.
365" turbo short block,
AFR 225 heads 72cc, 9to1cr
-11cc wiesco pistons
H beam rods polished stock crank,
ls6 intake, Z06 cam
1.8 yella terra RR,
single turbo PT76GTS, 4" intake, 3" dp .96 ar turbine, .75 ar comp.
COS3 efi live OS instock computer
60# injectors
Mostly street car AWD 4L80E
How much power can I make on low boost, 10-12#
How bad will the 3"DP choke my hp?
will it be mostly at high rpms?
THANKS

52172

iTrader: (2)

I've always been under the impression you can safely run up to close to 1000 crank hp before any problems should arise. Especially if its dumped. Otherwise a very free flowing exhaust.

sparkwirez06

iTrader: (18)

It's 3" all the way to the rear bumber

Slowhawk

iTrader: (12)

3" is going to kill hp through the whole curve and put alot of pressure on the exhaust valves.I figure 60-100hp in the mid. compared to a dump or 4" exhaust.

sparkwirez06

iTrader: (18)

don't make me go twins

SPRAYED 01

iTrader: (22)

I would agree that 1000hp is very possible. Just look at what they rate,t76,tc78,and similar turbos at. These are all rated at using a 3inch down pipe.

sparkwirez06

iTrader: (18)

I know almost all the f bodies were running 3" dp, until just recently when everyone got on the huge down pipe kick. Think I can reach 700hp with this setup?

Louis

iTrader: (7)

At the 850 wheel level, its worth well over 100 rwhp opening cutouts compared to through the single 3" Y pipe. Completely different car.

dfresh

I built a viper that made 1460 rwhp with 3 inch downpipes. Went to 4 inch, and it picked up 30 ft/lb torque down low and 25 peak hp. Don't be scared to run the 3 inch. The bigger pipes help, but not that much, especially below 1000 hp. At low boost(around 800 rwhp), there wasn't much difference.

eviltwin_1987

iTrader: (18)

key word, down "pipes". He is talking single turbo with 1 dp.

dfresh

I understand you point you are trying to make, and that the vehicles are considerably different. I am simply trying to make the point that big pipes,or pipe, make more power, but are not the holy grail of endless horsepower. If you put it on the dyno it won't make as much, but it will still put up a good number.

sparkwirez06

iTrader: (18)

Thanks for the replies,

dhdenney

iTrader: (53)

Thought I'd just continue this thread rather than start a new one..... What's the thoughts on a 4" DP with a 3" in the middle to get through the K member and then back to 4"? Or is it a bottleneck is a bottleneck is a bottleneck?

Photochop

iTrader: (74)

I have a 3" outlet on my setup off the turbo, 3" thru the k member, and steps up to a 4" pipe at the firewall thru a dynomax bullet turned down at the axle. Its pretty droney and loud under accel, been thinking about running a 3" e-cutout right behind the firewall in the stock cat. location and running a normal 3" catback behind that to keep it tame when not ripping on it. If anyones interested in my 3" to 4" setup I'll make a good deal on it.

396375

iTrader: (10)

With those cubes and that turbo you will see nothing with a 4" pipe.Even PT 88s run well with a 3" DP which by the way is the turbo you need.
Good luck.

dhdenney

iTrader: (53)

Ha, I got a good deal on the 80 but an 88 would have been nice. Exhaust side is 4" so I may do the "adapter."

pwrtrip75

iTrader: (8)

every elbow adds like 10' of pipe flow wise. Do like other said, run a 3" DP and then as soon as you can step it up, step it up...4" or even 3.5"

engineermike

I'm running a 3" downpipe that's about 5' long with 2 45's in it. From there, it's 3.5" all the way back, over the axle, and through a Magnaflow. I've run 146 in the quarter at full weight at 17 psi boost from a T76GTS. Backpressure numbers were only around 34 psi, which is quite low for 388 cid on the 76GTS. Doing some math tells me I'm over 900 fwhp on the 3".

dhdenney

iTrader: (53)

Nice. I bought my v-band and elbow this morning to take to my guy. I thought about just kicking the 4" back as far as possible for now and then work with getting it back with a muffler later. Sounds like a 3" intermediate probably won't make much difference.

dhdenney

iTrader: (53)

OK my stuff has been mostly welded up. We've gone with a 3" down pipe that makes a 90 off the turbo then pretty much straight back from there to underneath the pass side rear. I may just leave the muffler off.