G'day guys, I really hope someone can help me here. I'm an Australian expat living and working in Saudi Arabia. A few weeks ago, I purchased a 1982 C3. The guy I bought it from said that he had had a 400 small block installed but I have not been able to check this because my company moved me (temporarily) to a different part of the country before I actually bought it. Anyway..... it had rams horn exhaust manifolds fitted, both of which were badly cracked. The rest of the system is a mixture of some pipe and lots of welds!! I have found a "performance" shop here in Saudi that will make me some stainless headers and a stainless system, but what do I want?? What is the best combination of pipe diameter etc... to get the most power from the engine? I would much prefer a single system over twin pipes, so again, what size etc... Of course, I would love to just dial up a speed shop and buy a system but the freight to Saudi Arabia would be outrageously expensive. Any help or ideas here would be really appreciated. Thanks....

 

Go to http://www.headerdesign.com and use the header design program. You'll have to estimate your peak power and the RPM at which it occurs, but you can play with a range of values and get something that will work OK across a pretty broad spectrum. You can probably tell if the motor has a big, high RPM cam or not. It may be a basically stock 400. If so, headers and a larger cam would make a huge difference.

You'll probably end up with 1-5/8" primaries. With 16 gauge pipe that is a 1.5" inside diameter. You'll probably want the primaries about as long as they can fit under the car to satisfy the design parameters you get. Make sure they use mandrel bends. If they don't, then bump up the pipe sizing to compensate for the wrinkles in the bends.

Since you presumably have no emission laws over there, maybe you should have them build custom side pipes. Muffler availability would likely be a problem, though. Maybe a 4" round muffler body with 3" inlet and outlet, something for a truck. You'll want some form of heat shielding as well to avoid severe leg burns.

I wonder if you have some missing hangers. Strange that the manifolds cracked. Only other thing I can think of that might cause that is excessive exhaust heat from retarded timing. Never seen a car with both manifolds cracked.

What kind of labor rate (in US$) do you have to pay over there? Folks tell me that Saudis lift nothing heavier than money, and all the work is done by foreigners.

 

As far as the single secondary pipe goes, 3" should be adequate for any power level you build the 400 to, and is probably the biggest that will fit. My buddy with a Mitsubishi Eclipse makes 400HP at the wheels with a single 3" pipe. Exhaust flow is a function of horsepower, not displacement.

Make sure they build you a nice merge collector where the two banks are joined. Flowmaster makes a very nice piece. You can get a picture off their website and show your shop.

 

I'd also have the pipe collector flange be placed about 1/2 inch lower than the lowest part of the oil pan. Any lower, and you might be scraping the headers on bumps & dips. Any higher, and you will sacrifice the oil pan (although that's the situation on stock systems).

Good luck - :)

 

Thanks for the info mate. I found a site last night that talked about Tri-Y headers and they sounded pretty good. I thought about having 1 1/2 inch primaries, into a 2 inch secondary then into a 2 1/2 inch collector box. I much prefer single systems so I though that I could get both sides made like that then run them into a single 3 inch pipe all the way to the rear. Did the C3 originally have a twin system? If so, it would be an easy matter to split the system right at the rear so there is still 2 tailpipes sticking out.

There is supposedly emission laws here, but I have seen no evidence of them!! I thought about side pipes but I dunno how good this speed shop is and whether they'd be able to make a heat shield that looks good and isn't attached to the pipe!! I'll be back there in a few weeks and will go and have a chat with them. As for missing hangers, I haven't had the time yet to have more than a quick look at the car. It drove well, has new paint and the engine was rebuilt 8 months ago and, most importantly, I have always wanted one - more than enough reasons to buy a car I reckon!

I don't know what you mean by the labour rate that I have to pay. I'm on a tax free wage, get all my accomodation and food supplied and get 9 weeks vacation a year with the company paying for my tickets up to the value of about $1800 US - more than enough to get me back to Oz or pretty much anywhere else in the world.

Yes, the Saudi's are an inherently lazy race of people. If something ever goes wrong, it's not their fault. They always NEED to go home from work early. They love to blame the Western world for all the problems in the world, but they aren't shy when it comes to driving a Caprice Classis or a new Suburban! If all the foreigners were to leave tomorrow, this place would shrivel up and die...

 

Good thinking 99, one that I probably wouldn't have thought of. These ratbags just LOVE speed humps. One of their favourite pastimes seems to be to build a speed hump in the middle of the night, probably where it is needed the least and then DON'T put up a warning sign or paint it a different colour from the road!! My other car is a 1982 K5 Blazer and I've hit some of these cunningly camouflaged speed humps before and I'm sure I've managed to get the wheels off the ground - especially a PITA when you have a cup of Seattles Best at your lips!! :conehead

 

I meant "what does an exhaust shop over there charge you per hour of labor for something like building custom headers?" Over here it is $65-$90 per hour, and the hours add up quick on custom headers.

The '82 originally had a 2-1-2 system where a Y pipe took the two banks into a single pipe so only one expensive catalytic converter was needed, then split back out to two mufflers at the back. The crossmember at the back of the transmission should only have one hole for exhaust pipe to pass through, unless it has been changed.

If you're expecting these guys to build custom headers, they better be pretty good. It is a tricky and time-consuming operation. Headers to fit the car are very cheap over here, $80-$300 depending on coating options and thickness of materials, etc. Even if shipping and duties doubles the price, it would be cheaper than getting custom headers over here. But maybe your shop labor rate is only $15 or something and you have a very skilled craftsman available.

Tri-Ys generally don't do well in dyno shootouts between header designs. Boost low end torque over a small RPM range but don't do well on peak power. You don't need any low end torque boost if you have a 400, but you need to free things up to let it breathe even at 4500-5000RPM.

 

Oh, sorry. I don't know what they charge per hour, but a mate called them for me and told them what I wanted and they told him the equivalent to about $500 US to build custom headers and a full system, all from stainless. Another mate has had a few cars done and swears by them. I'll be back there in a few weeks and get it sorted...

What size hole was originally in the cross member? I had a look at headerdesign.com and it seems to me that the best size pipe would be to from 1 1/2 inch primaries into a 2 1/2 inch system?

 

Another aussie here, also long way from home.

If you change exhaust pipe size then the centre exhaust hangar will need to either modified or replaced. A new hangar for 2&1/2" is $20-$25 USD through most of the corvette suppliers. If you go to 3" get them to modify the current one.

Cheers,


:cheers:

 

Just a stupid question, but why do you prefer single systems? Most guys here that have the means have replaced their old, nasty y-pipe setups with true duals.

 

Those sizes seem right, but I believe the program gives you inside diameter. Tubing is sold by outside diameter, so you need to add for the wall thickness. 1.5" ID gives you 1.625" (1-5/8) outside diameter with 16-gauge tubing wall. This is what most street headers are because it is a size that works for most engines. There is some information on the site about selecting tube sizes nearest to the calculated optimum.

That's an awesome price for full custom headers and system in stainless. In the US that system would be $1500-$2000. The labor eats you alive on building custom headers.

Not sure what size the hole will be in your crossmember. Easy to modify for anyone capable of building custom headers, though. Several people on the board have had custom crossmembers fabricated to allow dual 3" pipes.

The program is probably suggesting 2.5" collectors on the headers, right? Once you connect into the Y-pipe, you'll want the single pipe coming out to be 3". This will give you a nice scavenging wave as the exhaust pulse sees the pipe size go suddenly from 2.5" to 3".

 

I've just always preferred the throaty sound of a single, big bore pipe. I'll be off in a few weeks to see what this shop can do for me - I guess I'll make up my mind then... :confused:

 

Yeah mate, I should have said inside diameter. Yes again, the program suggested 2 1/2 inch collector boxes. I'll more than likely go with a single system, but if I do go with the twin, I'll run the collectors into twin 3 inch pipes - it should breath nicely...

Pretty much everything here is quite cheap. I dunno what you would pay in the States, but it only cost me about $35 for a water pump for a 500 cube, big block Caddy engine. Parts for newer cars aren't too bad, but stuff for the older "iron blocks" is really cheap. Labouring jobs out here are normally filled with 3rd world nationals - Indians, Pakistani's or Sri Lankans. Some of these guys are highly skilled but still get paid bugger all, however, it is still more than they would be paid in their home countries...

 

Thanks for the heads up on the hangers, this place is apparently pretty well stocked and very professional - for somewhere in Saudi, that is!

Where are you from in Oz and where are you living now? I spent quite a bit of time in Dallas and was real tempted to buy a Vette there and bring it back to Saudi. I wanna do another 5 years here in Saudi then go back to the Sunshine Coast in Queensland, taking my new toy with me... :thumbs: