How Important is a Header?

[bravenrace]

I'm kind of new to this engine (2.5l in a TVR 2500M). I'm looking to raise the power level on this engine, and am wondering what the benefit, if any, a header has over the factory manifold. Just to be clear, I fully understand the benefits of headers in general, I'm asking about on this particular engine. My other mods would benefit from improved exhaust flow, but is the header enough of an improvement? Seems like I remember someone saying that the factory manifold is pretty good already, but I'm not sure if I'm remembering that correctly.

 

[Brosky]

I believed that it helped my TR6 quite a bit, but I also improved carbs and ignition at the same time. My headers are also JetHot coated on the inside as well as the outside and run cooler than a stock manifold.

 

[bravenrace]

Thanks for the reply - I was starting to wonder if no one here ever put a header on a Triumph before!
Still, I can't believe there aren't more people that could chime in on this. Anyone?

 

[kodanja]

I put a header on my 71' Tr6
seems to increase the hp a bit, and makes such a pretty sound too!

 

[Guest]

I have one too, but it was part of a whole engine refit so I can't comment on the effect of that part individually.

I jet-hotted it and it looks nice though...
/bcforum/images/%%GRAEMLIN_URL%%/grin.gif

 

[bravenrace]

Is there a significant difference in weight?

 

[duckspuddle]

I'm probably in the minority, but I'm convinced that my header has actually hurt performance in the rpm band that is most useful, that is, less than 4000rpm. My engine is 9.5:1 ported head, triple strombergs, GP2 cam, high ratio roller rockers, twin sport exhaust, lightened flywheel etc... At rpms over 4000 rpms, my motor screams, but I think that around town, I've lost some torque with the addition of the"group 44 header". You do get what you pay for in header design. Application is key. What do you want to do with the car? The primary tube length is important. If I had to do it all over again, I'd probably opt to spend the $650.00 on something else...like a Nissan limited slip rear end!

 

[YankeeTR]

A header is usually only worth the $$$ if it's used in conjunction with other engine mods to the intake, cam and perhaps the head porting.

Use of a header WILL reduce low speed torque...as will all of the other mods I mentioned. The original designers of these (and other) cars built them to be very docile in everyday driving situations.

I really want to stress that IF you make the change KEEP THE STOCK PARTS. With values of TR's on the verge of rising (as have Jaguars and Big Healeys), stock, unmolested originals and good restored cars will have the highest values. While this IS your car and you can do with it as you want, I don't think it makes sense to spend a couple thousand $$$ making 'upgrades' that will, eventually, lower the value of your car.

I have nothing against modified cars...I own a chopped, shortened '56 F-100 with a blown Chrysler Hemi and all MOPAR drivetrain. About as far from stock as you can get. BUT this ain't a TR...and TR's are going to be $30K and up in just a few years...and the nice, untouched cars will probably hit $50K...if you get the right buyer.

 

[LastDeadLast]

I tend to agree with the last two posts. I've got a TR that's got it's share of mods (cam, exhaust, headers, compression, carbs, just to name a few), and I do feel that the the headers to probably add power above 4000. However around town, the reverse is probably true.

My take on modifications: Do it. But realize that the next owner might not think the white-walled tires and shoed-in Chevy 350 is as cool as you do. Every mod that I've done can be taken off and put back to stock (or at least as stock as it was when I bought the car). With all that said, there will always be a place for modded classic cars, I've seen resto-mod Mustangs go for as much or more than originals. It's all about how much someone is willing to pay.

 

[Brosky]

I've got all my old parts, not that I'll ever put them back on again!

 

[bravenrace]

I'm probably in the minority, but I'm convinced that my header has actually hurt performance in the rpm band that is most useful, that is, less than 4000rpm. My engine is 9.5:1 ported head, triple strombergs, GP2 cam, high ratio roller rockers, twin sport exhaust, lightened flywheel etc... At rpms over 4000 rpms, my motor screams, but I think that around town, I've lost some torque with the addition of the"group 44 header". You do get what you pay for in header design. Application is key. What do you want to do with the car? The primary tube length is important. If I had to do it all over again, I'd probably opt to spend the $650.00 on something else...like a Nissan limited slip rear end!

You're engine is pretty much exactly what I have planned for mine, although at least for now I'm sticking with dual ZS's. I'm not sure I mentioned it before or not, but I can pick up a new but unknown brand of header for $150. At this point I'm thinking it's worth doing, as I can probably get that much for it if I end up not using it. It's not that difficult to swap, so I can try it an see which I like the best. It sounds like a reasonable risk to me. What do you guys think?

 

[duckspuddle]

Cheap headers often require a bit of work to fit well. Headers are notorious for warping with subsequent gasket failure. the flange is just not as substantial as the stock manifold. I've heard horror stories about grinding the header flange to get it to mate with the head, not to mention problems with port matching etc.... I've got the falcon two piece unit, and had no problems with fitting. I know of a couple of folks who like the performance of the cheap pacesetter...once they get it to fit. I would argue that ceramic coating is overkill on stainless steel. The insulating properties are nice both for temperature and noise reduction. I understand moss has a nice mild steel header that is reasonable, that once coated would probably be a good alternative. I would not bother coating a pacesetter until I was assured that it fit well.

 

[Guest]

I have the moss header, and jet-hotted it.
The nice thing about it was that it actually fit out of the box...

 

[MadMarx]

I've tried out the the stock unit against a not efficient tuning header and found a great improvement compared to the stock unit of about 7 hp.

My current racing header does a lot more....

This is how a TVR should sound...:

https://video.google.com/videoplay?docid=-7401778884355481580

 

[rotoflex]

My knowledge of Spitfires & TR6's is not much past knowing what parts don't fit on my car.

The TR6 engine is a stroked version of the GT6 engine (thanks to I think Andy Mace for pointing out the development order).

So there are similarities. As far as headers go, Kas Kastner in his GT6 Competition Preparation Handbook pointed out that fitting a header as opposed to using the stock cast iron exhaust manifold gained power in the upper end, but cost power in the lower end.

And not just a little. Notice that the header doesn't equal the stock manifold's power until 4,000 rpm. For a track car, this is not a big problem, but it is for a street car (which Kastner points out in the "Building a hot street GT6" section). Just as a daily driver, you'd have to keep the revs up over 4,000 to justify the header. Pulling away from stop lights would be sedate.

For a street GT6, the stock cast iron manifold makes more sense. It may be the same for a TR6.

A new design of header for 6 cyl Triumph engines has lately been available called the "Phoenix" extractor. Instead of the typical 6-2-1 design, it is a 6-3-1 design. A lot of folks have claimed it to be an improvement over the typical desigs & not only less detrimental at lower revs, but superior to the stock manifold. I've never seen a dyno graph comparison, though, so who knows. You can claim anything, & the "butt dyno" is hardly reliable. The variations being sold of the 6-3-1 headers are interesting: they can vary among other things in the length of the primaries, which in general header theory is where low rpm power is controlled. So with all these 6-3-1 manifolds being sold in various configurations - they're not all the same. Anyone who'll drop $600 on one, dyno it with a standard header & the stock manifold, & publish it would get my gratitude.

Kastner probably published a TR6 Competition Preparation Manual for British Leyland; you might watch eBay for one. Kastner sells on his website a compilation of some of the material he wrote for BL: <u>Spitfire, GT-6, TR-3, TR-4, TR-250, TR-6 Triumph Preparation Handbook</u>
https://www.kaskastner.com/kasbooks.html
Which will likely have very useful information for you.

 

[DNK]

I follow you with the results that Kas has done. I have 1 thought or question. The date of the test was 1967. Any chance the headers have improved since then?

 

[rotoflex]

That's what I referred to in the reference to the new "Phoenix" 6-3-1 headers.

Chance is for slot machines, show me the dyno comparison.

At least Kastner has published dyno graphs. The new header 40 years later does *not*, only sales pitch & butt dyno reports.

Also as mentioned, the new 6-3-1 type extractor designs have a lot of variations across vendors, & the most obvious is primary length. Variability of primary length of headers is NOT irrelevant, especially for smaller engines.

Street performance of the 6-2-1 type was shown by the dyno report to be inferior to the stock manifold. To get better performance over the stock manifold from the 6-2-1 header, the car would have to be driven as if in the racing application the header was designed for: holding the engine at the redline all the time.

Most people buy headers because:
1. They hear they will make the car go faster
2. They are shiny & expected to impress others

And they will be sold if people will buy them. It's amazing to think of all the GT6's that had headers put on for "performance items" & intended to be street-driven.

I cannot say if the new 6-3-1 headers are better than the stock manifold or even the 6-2-1 header. Nobody can, without a dyno comparison.

We do know the 6-2-1 header is inferior to the stock manifold for street use, because there's the dyno report.

 

[MadMarx]

I use my race car as a daily driver and go shopping with it, visit the restaurant or clients (only if they know that I do racing - Germans are a little envy of) or enjoy driving around.

Sure the car has not that tremendous power at low revs as it has beyond 4000 rpm but it has a lot more at the rev cellar than a standard TR 4. Even If I stay below 4000 rpm the car is very fast. It performs like a standard TR 4 with just more power.

 

[TR6oldtimer]

Thanks for the graphic. Made me think. So yes, for me a street driver I know I can find other things to do with $400-700, and it will help keep me from getting an exhibition of speed ticket, well just a little.

 

[trboost]

Just a few clarifications that would affect the dyno chart that was posted. It shows a GT6 engine, which as correctly stated has a shorter stroke (2.99 in) as compared to the TR6 engine (3.74 in). This gives the TR6 more usable low end torque. The results are also greatly affected by camshaft selection. This affects low end power much more than a header can. In Kastners TR6 dyno tests stock cylinder head except for an increase in compression (10.1) the comparisons between A)stock engine B) 10.1 CR, Vel stacks & valve grind C) "B" plus S-2 camshaft D) "C" plus exhaust extractor system. The results show A, C & D all produce the exact same power at about 2,800 rpm. The biggest differance was the "B" motor not using the cam or exhaust.

The job of the header is to extract the additonal air/fuel being used by the engine. The header is only part of the exhaust system. The muffler, pipe diameter and amount of exhaust pipes (single or dual)all affect the final result. I would not imagine you would notice a small change in power curve under 2,500 rpm. More often than not, when your right foot summons the horses to awaken it will be from 3,000 rpm's & up.

There is a happy medium we need to settle on for a street/performance set-up. These motors are not tuned with a lap top or chip. It's more basic & not an exact science along with a ton of trial & error. Maybe thats why I love it so much !!