Another one. Exhausted

[16SSWag]

Wouldn't it be great if Monstar was here to throw his 2 cents worth in right now

Hahahaha same thought popped into my head

 

[Not_An_Abba_Fan]

I don't think you understood why we had the head made with the smaller port...it was so WE COULD USE THE SMALLER PIPE rather than be stuck with a port that had to have a 1 7/8" pipe. That was no accident and done as building and racing these cars since the start of LS1 and hotties in general for over 30 years...it was an observation that bigger pipes felt flat under the curve. If you can't get the torque curve right in a LS between 4500 and 5500 you are doing something real wrong...from LS7 427 to cammed LS3 etc near all show peak torque at 45-5200rpm..it is what is happening before that point that gets a streeter out of the hole.

Here is a comprehensive write up on the LS cylinder heads and how the 4.0 came about. We spent a bunch of $$ making that head and put some design stuff into it that we gleaned from offroad racing 6L class. The same head is available with a larger exhaust port...it flows the same numbers.

http://www.streetquick.com.au/tech-articles/sqp-mast-4-0-cylinder-head


The hole in the middle of that torque curve would be nothing I would be excited about. As you know...the architecture of the vehicle dictates where you end up with headers...not something that is compromised on a race only design.

You guys build reliable and quick cars. You know a lot about the intricacies of what an engine needs to have to be able to perform. Street car headers are a compromise, always have been and always will be. To get a streeter out of the hole, the headers are all wrong. They are built to fit the car. If you lengthen the header primary and have them all equal length, the car will perform even better to 60'. 1 3/4" is a good size, getting the length right so that the engine stays in it's peak torque between gear changes is achieved through the primary length. Because both Pacemaker and DF use uneven lengths, I reckon you are losing a little bit.

I have always said, build a car and match everything to what you want to achieve, but people rarely have the time or money to custom build everything so they buy bolt ons. The aftermarket industry is huge because of this. 30 years ago we were custom building over half of the headers and exhausts that came through our shop. Now it's get them in and out as quick as possible to get the next customer in. I think you even said it in one of the articles, people want to having pissing contests with peak power dyno read outs rather than a car that is quick.

Cost is part of it for sure NAAF. Particularly when it comes to headers v cast manifilds. But, re OTR's and tunes, cost wouldn't really be a factor.
Out of interest, do we know why the LSA's didn't come out with piped headers in The HSV's?

With forced induction headers don't really play that big a role as far as scavenging goes. The HSV tri Y's are an improvement over the cast manifold for N/A but FI, doesn't matter, just need to move volume.

 

[426Cuda]

Hahahaha same thought popped into my head

ditto

 

[blackve76]

While ago talked with a neighbour whos has a VE wagon SS auto, commented it sounded nice(we live on a decent slope so under load going up hill) surprised it was just a x force 2.5' system.

Pulled up a lights other day and he took off a bit hard didn't sound so good, bloody exhaust are so subjective to ones ears.

 

[426Cuda]

Does anyone know what size bolt /thread would be required to block off the air sensor holes is a 340 HSV midsection?
Cheers

 

[dgp]

Cuda, if you are talking about a redundant O2 sensor bung, you will need an M18 x 1.5 bolt.

 

[426Cuda]

Cuda, if you are talking about a redundant O2 sensor bung, you will need an M18 x 1.5 bolt.

View attachment 197547

Ah, yes. Awesome dgp. Thanks mate!

 

[phantom0817]

Might not be the right thread but didn’t think it deserved a new thread.

I was really impressed with the exhaust on my SS except that it was quiet. What I loved was the crackle/pops especially on the overrun. Got a Walky catback (dpe 2.5”) based on sound and reviews but while the sound is deeper, I’m somewhat devastated that all the crackle/pops are completely gone. Ironically the exhaust is a lot more muffled, despite being deeper and louder, the character is gone. I thought for sure the crackle/pops would be caused by the tune or header, not the cat back but clearly It’s both.

Anyone know of any cat backs that retain the crackle/pop?

 

[blackve76]

Might not be the right thread but didn’t think it deserved a new thread.

I was really impressed with the exhaust on my SS except that it was quiet. What I loved was the crackle/pops especially on the overrun. Got a Walky catback (dpe 2.5”) based on sound and reviews but while the sound is deeper, I’m somewhat devastated that all the crackle/pops are completely gone. Ironically the exhaust is a lot more muffled, despite being deeper and louder, the character is gone. I thought for sure the crackle/pops would be caused by the tune or header, not the cat back but clearly It’s both.

Anyone know of any cat backs that retain the crackle/pop?

I fitted headers cats to the stick cat back and hated the pops and crackles, fitted 3" kpm better but tuned out the pop crackles now nice deep throaty v8 sound.

 

[KT11H]

Anyone know of any cat backs that retain the crackle/pop?

Now you mentioned it, there isn't any occasionally crackle/pop from my newly fitted X Force 1 7/8" header with 3" stainless steel exhaust system. now it just crackles/pops every time I press the accelerator.

I read it in an article somewhere that minute amount petrol is sprayed into the stock system to give the characteristic crackle/pop which happens when gas pedal is returning to its original positon after pressed. With the X Force system, it happened few times when the vehicle was cruising with a light throttle then brake hard then full throttle, it crackles and pops during braking before picking up speed.