Will headers improve performance of 308?

Replacing the headers is really only worth it if you have cracks or leaks. Unlike with a domestic V8, where replacing manifolds with headers makes good gains, with performance headers already on there, switching to an aftermarket or custom set might not yield really anything without making changes in other areas.

There are so many other ways of increasing power...and the easiest in the 308 is to reduce weight.

 

Sammy,

How do you reduce the weight ??

 

I think there is a whole bunch of stuff you'd do before you bothered to change the stock headers. Aside from making sure the thing is in tip top condition & that the carburation is bang on you'd probably look at the ignition system as a first port of call.

But as I understand it the major limiting factor on 308/328s etc is the size of the valves where one set are actually too big I think (can't remember which way round that is - but read up on it). As with any engine the power is in the head(s) & the design of the ports & the valves seem to be the limiting factor.

Of course if you get it to make more power it will make more heat & so your cooling system better be able to handle that - and then there is the brakes & suspension & so it will go on !!

As someone else has said, stripping weight out anywhere you can adds performance. Anything from light weight batteries, lightweight exhaust systems, lightweight wheels if you can find something that works, to removal of things like tool kits to taking out or replacing chunks of interior etc. Anywhere you can drop lbs adds speed.

 

There are plenty of ways of reducing weight in any car.

The best bang for the buck in the 308s is to remove the spare wheel/tire, air pump, the a/c compressor (if a/c is not needed or is not working), and don't keep the tools or jack in the trunk. This might not all seem like a lot of weight, but you'd be surprised -- especially if the original post author was considering doing headers for maybe a one or two hp gain, this will get the same or better gains without spending a single $.

BTW- there are other things that you can do to reduce weight, some crazy, some easy: old stereos and speakers are usually heavy, if you have a GTS -- keep your top in the garage (not in/on the car), keep only a little fluid in the windshield washer bottle.

As for other hp gains: get rid of the catalytic converter, change your spark plugs/wires and make sure your points, caps and rotors are in tip-top shape and timing set properly.

 

Sammy I am surprised that those few things will make any difference. My air pump is already gone and my a/c dosen't work, so maybe I will yank it out when I have my shocks done.
What do you do for a flat without a spare or tool kit?

 

I kept my spare tire in place, but it's inflated with helium. Now my front-end is so light it's like having power steering.

 

Removing 200 lbs from the car would potentially reduce the et by less than .2 sec and about 2mph. Removing the spare and ac might get you 75 lbs...not even worth .1 sec .2 sec is totally unnoticeable except to the timing system at the strip. I'd much rather have a spare tire and ac!

It takes about .5 sec improvement in the range of these cars...14.3 sec or thereabouts... to notice a reliable difference in power

 

I'm trying to lose 20 pounds so my car will go faster.

 

Rammer, that's pretty funny!

 

If you have 16's on the car, why bother with the spare..........carry tire inflater.......and when you remove your spare it will change the front suspension geometry some what. will need to lower the car if you want it to put it back to specs.

 

There's a whole lot of stuff in the car that you don't really need, and another bunch that is constructed heavy where you want it light.

Rear deck-lid is very heavy: put a plastic one one. Oops, you already have a plastic one
Exhaust: throw that boat anchor and put something light.
A/C: In a GTS? You gotto be kidding me. Take it all out, including all the stuff that runs front to back.
Central locking, electric window motors and door-panels, have you weighed that lot? Scary.
US bumpers? Put plastic Euro's on.
Spare, jack, tools? Okay, maybe leave the tools in there

There you have 250 pounds or so. You should notice the difference.

 

+1!!
there is a lot of weight that can be reduced!!!!
the 308's only problem is it's heigh weight don't carry things you do not need.
and then there are the supreme replacement-things like: titanium suspension(-12kg unsprong weight), lightweight raditiator, swaybars, alternator, flywheel, clutch, batterie, brake's etc etc
i make my own bumpers (example; +/-1kg piece instead of 5.5kg EU version, +12kg US bumper)
i think i got wrid of about 300kg, but have to weigh it (soon) to be exact but then mine is pretty hardcore
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Of course one COULD reduce 250 lbs but what a PITA to end up with what? It's just not worth the trouble and annoyance of driving such an annoying vehicle around except in 20 minute stretches with long breaks. Buy a different car! OR...As often noted, power to weight is the key. It's WAY easier to increase the power noticeably than it is to reduce the weight noticeably.

Dropping 250lbs just gets you a power/weight improvement from 12.3 lbs/hp to 11.3 lbs/HP. (based on 3200lbs/260FWHP to 2950 lbs). Bumping the HP to 320FW takes you to 11 and with a blower that's a pretty light HP change AND you get to keep all the stuff on the car that makes it a lot more pleasant to deal with.

For many years I drove cars that were "lightened" and they were/are extremely unpleasant to drive around though, of course, they were great on the track. SO if you MOSTLY drive the car on the track, it's fine. If not, IMHO, it's a total PITA.

 

Face it, if you are worried about 0 to 60 times or quarter mile, get a Corvette. Our 308s were never meant to be dragsters. A few HP here or there simply doesn't make much of a difference in the "seat of the pants" experience in driving these cars. Short of turbo/supercharging a 308, most of the things you do will not make a real difference in the power your feel behind the wheel.

That said, when I did the engine out service on the 308 two years ago, I removed the headers, stripped off the old heat shields and insulation, and had them Jet-Hot coated. The weight savings is not significant, but the Jet-Hot coating inside and out improves the performance of the stock headers, and the temperatures in the engine compartment are much lower than before I did the work. IMHO, that is a worthwhile exercise if you want to do anything with the headers.

 

+1 regarding getting a different car for drag racing.
Removing things like the spare tire doesn't make sense because these cars actually NEED weight over the front wheels for the brakes to work.

 

One thing I have also noticed with s/steel headers is the effect it has on the noise of the engine, it tends to give it a very metalic/tinny sort of noise. The standard steel manifolds have a lot more mellow tone.
Speed wise I found it just sharpened the response from the engine slightly and with the sports exhaust it felt as it was quicker due to the noise.

 

i haven't done this yet, but i am also planning to change my headers. supposedly, the US cars have narrower tubing for the headers compared to euro cars. making the change yields a noticeable improvement.

in terms of weight, if you have a US car, just convert to euro spec and will have saved 200+ lbs. i have no idea where all that US extra weight comes from, but it's there somewhere...

 

Most of it is bumpers/shocks...and don't forget door crash beams...

 

my point was mostly that for the performance gains you can get from just going to aftermarket headers, you can get the same (or better) gains for free. Plus, with lower weight comes the slightly more nimble handling and better braking.

When it comes to weight, the old saying always is true: the easiest way to save weight is to use a lighter nut behind the wheel.

 

...extra frame components and air pumps.

 

Ok, so most people here suggest to reduce weight to gain HP, I agree BUT,
exactly how much weight do you need to lose to gain one HP, what is the ratio?

 

i never get tired of seeing pics of your car, its lovely, and looks like it means business.

 

10LBS = 1HP My old 308 is under 3000lbs now which required major surgery but the lightness is felt and the car is still slow and nothing short of rebuilding the engine with close attention to installing parts that work together as a package is whats needed, you will see little gains if any by tinkering or beating around the bush. My old 308 has high compression pistons, free flowing exhaust, single distributor and some port work, its still slow by todays standards. Cams would round out the package but it still wont blow you away like a 430 would.