3" exhaust

[Superdave]

Hey all, i've been thinking about ditching my true dual 2" plans and going with a single 3" system. I'm just looking for some sound clips or opnions from anyone that's heard a n/a '660 with 3" single.

I'd be running a Hooker Aerochamber 3"in/dual 2.5" out Crossflow muffler. I know the exhaust will flow plenty, i'm just concerned with the tone...


this will be on my cammed 3500 with longtube headers and a hi-flow cat.

thanks for any information.


Dave

[1988GTU]

there's a link somewhere in the dohc section with a sample of my 3" exhaust, no muffler.

Link

[Joseph Upson]

Hey all, i've been thinking about ditching my true dual 2" plans and going with a single 3" system. I'm just looking for some sound clips or opnions from anyone that's heard a n/a '660 with 3" single.

I'd be running a Hooker Aerochamber 3"in/dual 2.5" out Crossflow muffler. I know the exhaust will flow plenty, i'm just concerned with the tone...


this will be on my cammed 3500 with longtube headers and a hi-flow cat.

thanks for any information.


Dave

3" exhaust is too much for a naturally aspirated V6 under about 300 hp.
You need the scavenging effect to help appreciate your headers and if the exhaust pipe is too big it will negate that by allowing the exhaust to cool too much before exiting. I believe GM ran 3" single on the V8 F-body cars all the way up into the 330 hp range in the 90s model cars, not sure if they switched when they developed the LSx engines.

Since you are using a muffler the wider pipe should make the tone a little deeper, however the muffler will probably have the biggest influence on the sound that comes out the end.

[neo71665]

Yeah 2.5 is about as big as i would go.

[Superdave]

3" exhaust is too much for a naturally aspirated V6 under about 300 hp.
You need the scavenging effect to help appreciate your headers and if the exhaust pipe is too big it will negate that by allowing the exhaust to cool too much before exiting. I believe GM ran 3" single on the V8 F-body cars all the way up into the 330 hp range in the 90s model cars, not sure if they switched when they developed the LSx engines.

Since you are using a muffler the wider pipe should make the tone a little deeper, however the muffler will probably have the biggest influence on the sound that comes out the end.

this engine should be over 300 crank hp. DD2K has reported around 350 HP at the crank with open headers.

I also want to leave room for fuiture work, may end up adding in a 100 shot next year.


i have clips of how the old 3400 sounded with the same muffler and 2.25" pipe

http://www.3500z.com/AV/Hooker1.wmv

http://www.3500z.com/AV/Hooker2.wmv

that's with gen2 manifolds on a mild 3400, 2" downpipe and 2.25" cat-back

[MidnightriderZ24]

ive got some sound clips of my 3'' borla xr1 .. its boosted but u get the point, ill have to upload them when im at home on my laptop

[PCGUY112887]

How do you plan on gaining over 100hp on a 3500 with just a cam and headers?

[Superdave]

How do you plan on gaining over 100hp on a 3500 with just a cam and headers?

huge cam, longtube headers, lots of porting/polishing, #36 injectors, UDP, bumped up compression to around 10.8:1 or so. I put all the specs in Desktop dyno and that's what it says. it's usually pretty accurate...

It's been built for over a month, just waiting on one last thing so i can get it fired up...

[ForcedFirebird]

huge cam, longtube headers, lots of porting/polishing, #36 injectors, UDP, bumped up compression to around 10.8:1 or so. I put all the specs in Desktop dyno and that's what it says. it's usually pretty accurate...

It's been built for over a month, just waiting on one last thing so i can get it fired up...

36# injectors are awfully large for a N/A 660, no? The 24# Denso's (blue top Ford) that I have are rated to 250hp at 80%.

What are you doing for tuning?

[Superdave]

36# injectors are awfully large for a N/A 660, no? The 24# Denso's (blue top Ford) that I have are rated to 250hp at 80%.

What are you doing for tuning?

they're #32's from a GMC Typhoon, just running them with the '02 3400 54PSI FPR (ends up around #36). According to the online calculators they're perfect for my application.

tuning... just using the stock '7730 ECM and my old custom chip for the 3400 to start with.. then lots of datalogging and adjustments till it runs right.

i've got a few sleaves of 27C256 chips so i shouldn't have any problems there.

[boostedrs]

http://2wai.ics-il.com/2.8.flowmaster.idle.wav

2.8L with high cr and huge na cam headers and single 3 inch back to a 80 series flowmaster.
sound quality sucks took it with a cellphone but u can still get the idea from it
and

http://2wai.ics-il.com/takeoff.wav

[SappySE107]

What are you using for input in DD2K? I wouldn't use its numbers as a baseline for anything, but rather only to see the way mods change the powerband.

[Superdave]

What are you using for input in DD2K? I wouldn't use its numbers as a baseline for anything, but rather only to see the way mods change the powerband.

when i put in the stock 3500 specs it came up at like 220 HP or so.. Anyone whos used DD2K knows it can skew results alot. Ben, that screenshot you saw before was the extreme version. After i toned down the head flow, input CFM and changed the exhaust it dropped to around 300 HP.

After it's all tuned i'll be taking it to the local dyno and track, then we can discuss real results..

But for now, Thanks for the exhaust clips guys!

[AaronGTR]

I still think a 3" single is going to be more than you'll need, but it will certainly be better than dual 2". The duals would be heavier and they'd have more surface area which would mean more cooling effect and more friction in the gas flow. The 3" single should keep better velocity.

[Joseph Upson]

I still think a 3" single is going to be more than you'll need, but it will certainly be better than dual 2". The duals would be heavier and they'd have more surface area which would mean more cooling effect and more friction in the gas flow. The 3" single should keep better velocity.

That's what I was thinking for my twin turbo setup but when I did the math I came up with more flow area for a single 3" diameter pipe than I did for dual 2" diameter pipes of the same length so I switched to dual 2.25", unless I calculated incorrectly it's either excessive area with 3" or near just right with dual 2" and a bit more exhaust cooling.

I don't believe the weight will be that significant for duals if he uses 18 gauge tubing to run the length of the car as opposed to 14 ga. I'm running 16 ga stainless from manifold to turbo, and 18 ga mild steel exhaust.

I just computed a test run in a airflow calculator and it seems to support my calculation; 100 cfm through a single 3" pipe vs. 50 cfm (have to divide) through dual 2" pipe and the latter showed a higher velocity which would coincide with airflow through a smaller area.

Hopefully it will link:

http://not2fast.com/gasflow/velocity.shtml