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Question on Headers and Cats..

Not_An_Abba_Fan

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I never said tri Y's don't work. I recommend 4-1's. Sound better, go better.

Darren DiFilippo is a manufacturer, he pushes what he makes. Street Machine are a commercial enterprise, they push whichever advertiser pays the most.

As I said, there is very little difference on a dyno between tri Y's and 4-1's, just torque delivery. 4-1's will have a longer torque curve due to the way the exhaust gases collect. Tri Y's are also called "interference" design, because the gases collect sooner and the pulses interfer with each other.

I'm not saying I am 100% right, exhaust design and theory is all over the place. What works on one engine may not work as well on another. The best exhaust for power is none at all. One pipe off each exhaust port, tuned to the correct length for the application will see the most power produced on a dyno. Why do top fuel and funny cars run this type? Most exhaust design on race engines, you will find are the way they are because of regulations more than optimisation. They have to run the best that they can and still be within the rules. Noise is probably the biggest deciding factor.

If you Google enough, you will find supporting arguments for all theories. To have the best exhaust header design for your particular application, all sorts of things have to be taken into consideration, intake size, runner length, valve size, duration, exhaust port size and length, valve overlap, compression ratio, exact displacement. Millimeters either way in some measurements can make as much as 1-2kW difference in the final result.

Does all this matter on the street? Probably not, but you will sound like a genius at the pub.
 

Not_An_Abba_Fan

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I'm no expert, but from what i've found and learnt over the years is that:
Tri-Ys are better for low down
4-1's better for top end

Yes and no. Really long tube 4-1's (40" and over) are actually better for bottom end, short 4-1's (32") are better for top end.

BUT, the Tri-Ys beat the 4-1s in LOW DOWN by such an insignificant margin (1-1.5%) that its not worth giving up the extra top end power.

If you want more power, but not alot more noise, go for some HSV headers and cats. The cats are the same as regular holden ones, however the headers are a mild steel tri-y system, can be bought almost new on ebay for under $300 (for headers and cats!) from people who have taken them off their cars.

I put some from an e3 maloo onto my 07 WM caprice, straight bolt up, sounds nice and looks factory (because well, it is.. i guess..) Shouldn't cause issues with the fuzz or insurance either.

To put it into perspective, i have 195rwkw stock, bumped to 209 with HSV headers, cats and a 2.5" HM Perry S/S exhaust without a tune. Did you do a comparison with just headers, or after you replaced the lot? My opinion is that the cats and system would have netted you the most gain. HSV headers are better than cast manifolds, but not 19 kW better.

I then got a 219/224 cam (only a baby cam) OTR and tune and got 280rwkw.

I think id be up around 295-300 with some big honken (and expensive) 4-1 headers and cats but for a <$300 upgrade done in my drive way in like 2 hours, totally worth it!
That's the key though, bang for buck. To get the absolute most after a cam and tune, big headers, high flow cats and a good system are a must. I'd put money on the fact that you will easily crack 300kW by just doing headers and cats. Proper high flows, not the HSV ones.
 

mikey-

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To put it into perspective, i have 195rwkw stock, bumped to 209 with HSV headers, cats and a 2.5" HM Perry S/S exhaust without a tune.

I then got a 219/224 cam (only a baby cam) OTR and tune and got 280rwkw.

I think id be up around 295-300 with some big honken (and expensive) 4-1 headers and cats but for a <$300 upgrade done in my drive way in like 2 hours, totally worth it!
I have just a smidge under 280rwkw (274 or so I think on my dyno sheet) without a cam, but I have a full exhaust (1 7/8 4-1's, 200cell cats, twin 2.5" cat back), OTR, and mafless tune.

To be honest for all the money you spent getting your cam, wouldn't it of been easier to just get bolt ons and keep the motor un-opened? I couldn't imagine spending money on getting a cam without giving it a decent exhaust to breath as well.


and theres the pub too, "what extractors you run?" "1 7/8" 4-1's"...."cool"....
So true, love looking in a mates engine bay with 1 5/8th Tri-Y's, then looking in my engine bay at a serious set of pipes :)

-------------------------------

To the original poster... I have an SS wagon with a full exhaust as described above. Big extractors and high flow cats. When cruising, my car is whisper quiet! At 100 and 110kmh in 6th there is absolutely no exhaust noise in the cabin. Don't be scared to go big, I wish I went twin 3" but was scared of drone.
 
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Turtle2388

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Very, very informative NAAF! fantastic reading! But mikey yours is manual yea? I want to go 3` but I'm concerned about drone on the auto. I've been In an auto with xforce and drones at certain rpm. I'll be going manta full system from NAAF soon.

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Turtle2388

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From my countless hours of advice and research on the internet, phone etc.. NAAF has provided the best advice and between that and YouTube I made my mind up getting the identical system to mikey. Manta seem to be a quality system. And sound good! Love the note of your wagon mikey! Just gotta be patient for the tax man to hurry up :/

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mikey-

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Yeah mines manual.

I need to make another video, few mates have commented how much better it sounds now that it's carboned up a little and tuned. Fair bit deeper I think, its hard to say from inside the cabin though?


In that video I made it was basically brand new, probably didn't even have 50km on it....

Best bit about NAAF's system is that it is 100% going to bolt up, fit well, and is very achievable on your shed floor.
 

Turtle2388

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Yea I can't wait to get my tax return back. It's been 28 days and still no sign or it :( I'm planning on doing the whole system myself for the first time lol. It sounds good and is very well priced and shipped to your door! Then I'll get OTR and tune after that will just ignore the engine light for a few weeks.

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anarklov3r

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Hey mikey,

True, however things didnt go the way i had planned. I planned to only do a cat back with HSV headers and cats for a cheap "sound and go" package that i did myself. Car is running direct injected gas (vapour, not liquid)
I had the lifters go on the engine (its an L98 6litre) which also ####ed the cam. Sounded like a tractor. Had to get new lifters and a cam, so i figured i'd may aswell. Any bigger of a cam and this car wouldn't be a daily, and any bigger id have to ditch the gas system.

But 100% correct, If I knew i was getting a cam + tune + otr, i would have gotten bigger headers and cats. I also wouldn't have bought a car on gas if that was the case (if i knew id be getting a cam!)

I'm not after huge power figures TBH, because lets face it, you can't use it unless youre on a drag strip! That said, the cam, although didn't add ALOT of power (its an auto too, yours is a manual) boosted the torque and 0-100 speed alot. It's got enough power to kick this 1.9tonne boat out sideways going 60kmh in a straight line on a sunny day with 9.5" wide rear tyres. So sure, the dyno results might look disappointing but take it for a spin and you'll see where the moneys gone.
 

mikey-

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Yeah that cam would have a mean torque curve! But your answer 100% explains it why you've done what you did, and also agree that the top end figure although what we all go for, isn't a great indication or how a car drives day to day....
 

Not_An_Abba_Fan

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the top end figure although what we all go for, isn't a great indication or how a car drives day to day....
I wish more people thought like that. For some, it makes no difference how it drives, just a big kW number is all that matters. Because that makes ALL the difference.
 

HamaTime™

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I wish more people thought like that. For some, it makes no difference how it drives, just a big kW number is all that matters. Because that makes ALL the difference.
Agreed.

The power curve/torque is more important than a number.
 

mikey-

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I still tell my mates mine made more on the dyno though :beer chug:
 

anarklov3r

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I don't know what else to say... I feel.. at home...with smart people.....

My thoughts exactly.
 

mikey-

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The argument for big cams is that with their high top end, they will be faster down the 1/4mile, and for the most part, this is true, although not always....

What I found interesting reading through some Pontiac G8 forums is that alot of guys have tested several fairly conservative split duration high lift cams... They are obviously much nicer on the street, but due to the massive weight of our cars are proving to be comparable down the 1/4mile to much longer duration cams. This is due to the heavier car really utilizing the much fatter torque curve rather than just revving the rings off your engine with a huge cam...
 

PIR4TE

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The argument for big cams is that with their high top end, they will be faster down the 1/4mile, and for the most part, this is true, although not always....

What I found interesting reading through some Pontiac G8 forums is that alot of guys have tested several fairly conservative split duration high lift cams... They are obviously much nicer on the street, but due to the massive weight of our cars are proving to be comparable down the 1/4mile to much longer duration cams. This is due to the heavier car really utilizing the much fatter torque curve rather than just revving the rings off your engine with a huge cam...
True. Guy doing my upgrades retains AFM, runs a 221/225 .558/.564" 113+1 and its torque pulls a fat G8 to 11.84 at 122 on stock gear and converter.
He says smaller cams on tighter lsa with our heads and intake seems to do much better than larger cams which cam be hit or miss plus all the draw backs of large cams.
If you have airflow and heads that will support it, less duration with more lift will make broader power and give better street manners.
Follows an older article on the little cam that could... 219/223-duration, .625/.625-inch lift, 112 LSA article in GMHTP http://www.gmhightechperformance.com/tech/lsx_engine/ghtp_1108_ls1_engine_cam_test/viewall.html
 
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mikey-

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That second cam you mentioned is very close to what I had my eye on for awhile...

This is a weird series of posts... Seems to involve thought, reason, and not much 'I won't ma car 2 go wub wub wub at da lights for ma boiz....' Haha
 

anarklov3r

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Looks just like my cam :) 219/223 @ .600 i believe. not as much lift
 

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to VE_Calais at the end of the day probably the best advise is to go the drags or car shows and talk to people face to face and listen to their cars and ask them their opinions . I'm not an exhaust guru nor am I trying to sell you something but I've been driving modded street cars for a long time,
mild to wild , I have used 4 into 1 extractors & tri Y's for different applications ,twin 2 1/2 & twin 3" exhausts as well

enough said
 

Not_An_Abba_Fan

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That second cam you mentioned is very close to what I had my eye on for awhile...

This is a weird series of posts... Seems to involve thought, reason, and not much 'I won't ma car 2 go wub wub wub at da lights for ma boiz....' Haha
This sums it up I think

I don't know what else to say... I feel.. at home...with smart people.....

My thoughts exactly.
Retaining the MAF gives a much more refined tune. You can tune your trims at all rev ranges not just at WOT with MAFless. You will get smoother delivery and better economy with a MAF tune, and it keeps the EPA happy.
 

Turtle2388

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30 days no sign of tax still... I want my exhaust god dammit!!!!!! And my tune. But I was told the same maf tunes are the way to go with a street car.

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