So like most of us I typically use the 'ole standby 1.5" schedule 10 304.

But, I have a few customers that are very weight concious (car-wise :1) so I am thinking about branching out- provided they will pay for it of course.

The one customer in particular wants to run anti-lag, which is hard on manifolds, otherwise I'd be inclined to just try 16ga 304.

Chances are it'll be 16ga 321, or maybe 18ga 321, but again anti-lag is nasty.

Any thoughts? Obviously I'll be backpurging here. Cost for u-bends is typically $35-$40 a bend for 1-3/4", 2" radius, 3" legs? Any sources anyone has had particularly good luck with?

 

adam at racing solutions is the man for mandrel bends.

i'd just go with 304 and brace the turbo.

 

Good to hear from ya, greetings from another Canuck!

Just staying 304 is in the back of my mind- I would be adapting the existing sched 10 design which is braced already....

What I am going to do is build the new 6 cylinder manifold for my own project car from 16ga 304 as a "science experiment". I'm always just nervous about selling a material thickness/quality combination that I haven't proven out.

If I can make 16ga last, I'd rather use it obviously since it is so much easier to cut and fit than sch. 10. Cost/time wise it'd probably work out around even.

The big difference will be that backpurge will become necessary, at the moment I weld the sch 10 at around 60 amps, get ~80% penetration and call it a day, the heat affetced zone in the pipe will fail before a weld does. But easier cutting should offset the extra effort to backpurge and result in a more "professional" product overall I think. Sorry I am rambling... I think out loud a lot...

 

Just because 321 has a little extra strength in it at 1100-1700*F. There is no point in paying the high price for it. Only shops that are trying to coax money out of people use it.
I promise... .05+ thickness of cheap 304 will last ALOT longer than .04" 321 and do it at 1/3-1/4 the price.



If they can't afford the weight of a turbo, manifold and associated systems. They need to wake the ---- up and get a bottle of the juice.

 

LOL! that is quotable right there.
It's actually an autocross car and they are obsessed with weight - the car has so much grip it is 2 wheeling quote a bit on R compounds, so they are doing everything they can to lower weight and CG. It is currently turbo and has a cast iron manifold- so they're looking to shave some weight.

My sched. 10 headers are actually 2-3 lbs heavier than the stock one thanks to actually having runners.

Thanks for the insight guys!

 

2-3 lbs? If their that worried about weight. Tell them to drop a few lbs themselves. It's cheaper also.

 

Welcome to competition man.

We are talking about folks who actually weight the fasteners they use.
Competitive autocross racers are a different breed. Shaving 5 pounds off of a 13lb part gives them a huge hard-on. Who am I to argue? Different goals than most, that's all, and it does all add up.

 

a stainless manifold is an expensive science project. i did this manifold in mild steel 1.75" bandrel bent and no brace. it held fine for the year i ran it... and i ran it hard on the street and at the autox track a couple times. you can see the gussets i added to it on the back side.

 

tell them the general non-fast car general 1/4 mile racing rule is 100lbs = +10 peak brake horsepower.
i bet if you tell them that your hourly pay should equal your pound to engine performance ratio they'd be okay with it!


Im serious... honest to god Id tell them if they want to run anti-lag on a heavy-use auto-x car. i'd flat out tell them that they should leave the descision on what to use up to the person making it. beyond that if they want to shave weight they can be happy to use my 4 1/2" Makita angle grinder on their block and heads al they want. Im serious...