Exhaust headers, LS series engines

[Rebel1]

Ermmmmmm, Sambo....what car?.

[Rebel1]

Thanks Boxhead....much appreciated.

Cheers

[HSVREDSLED]

Originally Posted by Rebel1

Hey, thanks loads HSVREDSLED, guess that proves a point.

Given that often our finances are stretched and we have heaps of other things to spend money on, then that proves that using a standard manifold is an excellent and inexpensive option.

Cheers

True...for a standard engine....but who leaves them standard? You will soon get sick of standard. LS1's are so easy to get hopping through Cold air/Tunes which is reasonably inexpensive, then you will benefit from after market headers and future proof for the inevitable Cam upgrade.

[Plums]

Originally Posted by HSVREDSLED

True...for a standard engine....but who leaves them standard? You will soon get sick of standard. LS1's are so easy to get hopping through Cold air/Tunes which is reasonably inexpensive, then you will benefit from after market headers and future proof for the inevitable Cam upgrade.

This has been my point from the start...

Most people get a tune when they get VATS turned off in the PCM, this is before they have even started the thing. Most that I have done get a full custom, twin table MAFless tune.....

[HSVREDSLED]

Oops double post...

[Aussie Mike]

I remember when that header test was done for Street Machine magazine. It was several years ago and there weren't many larger sized headers available then. I believe the only real tuning program was still LS1 Edit. It was also a bone stock 5.7L LS1.

Tuners have been making more and more power since then as they have learned what works and how to get the most out of the various tables available to them. Newer versions of tuning software have also opened up more of the ECU to adjustment.

I don't think rule the years of development done by people on LS1 engines in Commodores, Corvettes and Camaros just because it hasn't been done on an LS1 installed in a Cobra?? that makes no sense. The rules are still the same, a primary tube of W diameter with a length of X int a collector of Y diameter and a collector length of Z. It doesn't really matter what car it's installed in.

I think the biggest impact on low end performance is the Side pipes. They just don't have a long enough collector area. From memory that collector really needs to be about 15" long

As has been pointed out, none of these motors stays standard for long. Les, you yourself have several times mentioned to me that you plan on changing out the lazy factory cam in your L76 to wake it up. So I think an exhaust should be built to fit the end product rather than what works now Unless you want to spend more money on another set of headers down the track.

It doesn't matter to me either way if people buy Ian's headers or not. They seem like a reasonable buy for the money as long as you aren't chasing all out performance. What got me fired up on this tread was Ian's arrogant response.

Honestly though who needs more bottom end in an LS1 powered Cobra. My low end robbing 1 7/8" headers still make the car turn the tyres in any of the first 3 gears from bugger all revs so I think I've got enough bottom end. I reckon mid range and top end are going to be far more usable. It's a formula that has been working well for Ferrari and Lamborghini. They design their cars with smaller capacity multi cylinder engines that rev to buggery and make heaps of mid range and top end. Bottom end grunt is great for towing stuff and getting a heavy car off the mark but my Cobra weighs about 800KG less than a commodore and I don't own a pop top camper.

Cheers

[Rebel1]

You know....what has me bu$$ered is exactly how much is enough.

Like, I'm looking at the LS1 site and in the GM Motorsport forum. In the stickies there is a post about a SS Thunder ute with a 6 Ltr completely standard ( stock exhausts) which did a 13.9 @ 102 (about)

Then underwent a mafless tune and did a 12.9 @109.5...all bog standard with bugga all miles on it.

And all the while having traction problems!!!!!

Now this thing weighs what??....1625Kg.?.

I'll leave it to the more expert than me to guess what this same powerplant in a say....1140 Kg.? cobra would achieve.

My post clearly mentioned Street car as opposed to track cars but also mentioned being able to blow off most ex showroom cars.

Sure, most of us will install aftermarket cams etc but my point stands...the stock manifolds will not stifle a standard ( as presented for rego) lightweight cobra which can in that stage of development give a hell of a fright to most cars ex showroom.

There is another area which I suggest many on here don't realize. You can build these things...purchase the best brakes, springs, shocks and all sorts of mickey mouse stuff and I'll bet.......you $hit yourself first outing.

You'll more than likely find it wont stop, wont go around corners and you'll find yourself wondering what the hell is going on and having to spend more money than you planned on sorting the thing out.

I'd prefer to get it handling and stopping properly before I find myself short of money because I spent up big on some go fast stuff.

My point is...you really don't have to have all the best of everything ie. cams, extractors etc., to have a well performing cobra...the lack of weight is your best friend.

Cheers

[HSVREDSLED]

Originally Posted by Aussie Mike

Honestly though who needs more bottom end in an LS1 powered Cobra. My low end robbing 1 7/8" headers still make the car turn the tyres in any of the first 3 gears from bugger all revs so I think I've got enough bottom end. I reckon mid range and top end are going to be far more usable. It's a formula that has been working well for Ferrari and Lamborghini. They design their cars with smaller capacity multi cylinder engines that rev to buggery and make heaps of mid range and top end. Bottom end grunt is great for towing stuff and getting a heavy car off the mark but my Cobra weighs about 800KG less than a commodore and I don't own a pop top camper.
Cheers

For the record, I think the pipes on offer look well constructed and are a good price. If I was in the market I would probably buy them.

I guess the difference between discussing the LSX donk in a Cobra and in its usual Holden/HSV is that in the latter, every possible rwkw is attempted to be extracted. However with 800kg shed over a Commodore, Im surprised you guys get any of the neddies to the tarmac. If robbed low down torque is your dilemma, diff gear change may be your friend and keep your current pipes and increase gas velocity through higher revs.

Now I just gotta think of a way of shedding 800kg from my car.

[Rebel1]

Originally Posted by HSVREDSLED

For the record, I think the pipes on offer look well constructed and are a good price. If I was in the market I would probably buy them.

I guess the difference between discussing the LSX donk in a Cobra and in its usual Holden/HSV is that in the latter, every possible rwkw is attempted to be extracted. However with 800kg shed over a Commodore, Im surprised you guys get any of the neddies to the tarmac. If robbed low down torque is your dilemma, diff gear change may be your friend and keep your current pipes and increase gas velocity through higher revs.

Now I just gotta think of a way of shedding 800kg from my car.

In many ways you are correct.

[Rob. Smith]

I've seen a ford 302 injected with a crossover and side pipes...looks good and seems to work !

[Beejay]

Lobelly,

Is this type of response necessary? You could have made your point without consulting the dictionary. I thought this forum was just a group of enthusiasts having an informal chat to help each other out and talk about cool cars.

"I guess the assessment is (again) a matter of opinion. If I were weighing up someone in that manner - in the context of their posts in this forum - I guess I would have to look at the level of vitriol, the respect they show others' opinions, their capacity to support their arguments in a cogent manner and the degree of circumspection and qualification they add to their opinion."

I am not sure why you are putting crap on Plums. In my book anyone who tunes LS1's for a living does not have to provide raw data to anyone to prove themselves. He offered his opinion, and I am sure some people appreciated the advice.

Have a nice day.

Ben

P.S. Ian, the pipes look good, I probably would have bought a set if they were available last year. Hopefully more CR parts will become available in the future.

[LoBelly]

I think its probably true to say that we agree Ben

I too think that Plums is entitled to his opinion - and if you read my prior posts you will see that I welcome them and hope that they continue.

Plums clearly has a lot to offer.

However, I don't think its fair of Plums to ask Ian for Proof if Plums isn't willing to hold himself to the same standard.

So - for complete clarity - I think that it is fair of Plums to add his opinion - based on his experience - and to let people weigh what he has to say about something. (and I'm glad we now agree that it was opinion)

And at this point I hope you will also note that I'm not actually taking a side - just asking for fairness in the argument.

Accompanying that sentiment is, as expressed in the section you've quoted, a general desire to let people have their opinion without running others down. I don't think that Plums was the one doing that. (interesting that you thought it was directed at Plums - maybe because it followed his post - I can assure you that was circumstance)

Naturally the generally good natured banter about the choice of colour of one's engine is an entirely different matter.

As to the way in which I write - I am attempting to reform.

You raised some plus-good points Ben and I'm glad that you prompted me for explanation.

LoBelly

[macloft]

Right so I waded through this thread after watching the rugby (go you good things hehe).
I have a standard pair of holden headers like the photo in Rebel 1 gallery.
Unlike the rest of you I have to scrimp and save so I can not afford a set of chevy headers for my Harrison anyway
I offered the headers up to the motor and SAMBO they dont fit. They both hit the chassis side members.
I then turned them around ala Rebel 1 suggestion and they hit the engine mount
Soo thinking what do I do
1/ mill the flange on an angle to tilt the headers inwards
2/ cut the flange off and reweld it. Not to strong on cast iron welding skills. Maybe I braze it back?

I think I will try 1 first.

Next I need to cut the large flange off the end of the header (as this is a tight fit between the starter motor and the chassis) and braze?? in a piece of tube which will curve around and underneath the car. the tube would have a flange on it to bolt up the rest of the exhaust system.

Now a question
Knowing the clearance underneath is tight could you split the system into FOUR smaller pipes at the back each with a muffler. Would this work or has the thrashing of the wantabies left me light headed.
Cheers
Bruce

[Rebel1]

Bruce, also try swopping engine mounts left to right as well as exhaust manifolds left to right.

This means the exhaust dumps to the front of the motor and you need to fabricate a J-pipe to redirect the exhaust rearward to the system.

ArshCobra did the same with a factory five in the states. see his post here:

http://www.ffcobra.com/ubb/ultimateb.../t/000150.html

Cheers
Les

[Aussie Mike]

I wouldn't bother with the factory cast Iron manifolds. I reckon they are probably more trouble than they are worth.

I picked up a pair of factory Corvette exhaust manifolds on ebay for about $80 shipped to my door. These are pressed steel and a lot easier to work with. I cut off the outlet pipe and collector part and fabbed up my own outlet and welded it on. These are the basis for my quiet under body system. You can buy new O2 bungs and weld them in and it was a pretty easy excercise to make these manifolds fit.



There's a couple of different designs of pressed steel exhaust manifolds for the LS1 out there but I think the Corvette ones are the easiest to work with. I've got a pair of Camaro ones as well but they are quite different left to right.

Cheers