odonnell

A buddy has a set I could get for a good price. My concern is that they will sacrifice midrange power for top end, that seems to be the rule of thumb for tri-Y manifolds versus 4-1 headers. This is a street car so I have no interest in sacrificing anything below 4500rpm. Anyone know if this is the case for typical 944 long tubes (Stahl, MSDS, etc)? Mainly looking for improvements all throughout the power band, I know they are not huge, or at the very least, improvements in places without losing out in others.

Jeff951NJ

Stahl header is the only way to go if you can find one.

odonnell

Is there objective data in terms of power tradeoff? I'm all ears.

V2Rocket

^not after you put headers on - you'll be deaf




really though, it of course comes down to the primary length and the tube diameter. certainly don't want/need to be any bigger than the head exhaust ports. long tubes should only help your low/mid range and still be great up top.

944 spec guys were (are?) allowed to use the MSDS or Bursch headers but from talking to a few the impression I got from them was "it only makes the car louder, not faster" but perhaps that is related to the rest of their regulated engine setups. a car like yours without "limits" and in a freer state of tune might be able to take advantage of the headers...

4-2-1 helps spread the torque curve out, 4-1 should make it hit harder in a narrower range (assuming they're all about equal length).

odonnell

Yeah that's what I figured...these cars aren't that special. 4-2-1 sounds like the best fit for this car. I'm also against making it louder. Cat delete (resonator in place) and a stock replacement muffler sounds awesome and refined without drawing any real attention.

951Dreams

On another place where 944 guys like to gather and talk, there's a guy who's spent all of his live long days doing everything he could possibly think of to get the most out of 2.5L NA engines. After many builds and dyno testing, he came to the conclusion the stock headers where just about perfect for a street NA.

His feeling was that Porsche realized the NA was gutless off the line, and tuned the exhaust to give it all they could get on the low end. His experiences showed any move away from the stock setup moved the curves higher, and the final determination was a/m headers only benefited those who raced and spent all their time in very high RPM ranges.

I can neither confirm or deny these findings, but he had lots of pretty graphs, maps, and really convincing sounding engine maths to back up his feelings. For all I know he made it all up. But I was convinced.

I would like to link to the post for all to read except A) It's another forum B) I have NO idea what thread it was in... sorry.

V2Rocket

^^ was that by chance a guy named Terry?

Noahs944

My only experience with long tube headers existed with other mods.

And it was with the expensive STAHL. The car was better with them.

Racing rpms... like 4000-6000+?

I have a tough time differentiating between spirited drives and "racing"...because when I'm having fun it ALWAYS in this range. Maybe not racing but the engine doesn't know the diff.

note: I noticed a quality difference between my MSDS headers for the 924 "Gramps" and the Mantis spec'd Stahls (1 3/4" or 1 7/8" primaries & 3" collector "secondary". The fitment at the flange where the ports are looks like expensive high end hand fitted pieces on the Stahl. Not trying to beat down the MSDS, but in this case you get what you pay for.

Anyway, the car breathed really really well at 4000-6000+, so it fit the type of driving I do when I am expecting results from the engine.

951Dreams

In short, yes....

We'll see how much a turbo changes my driving habits, but I consider that "race" driving.... Maybe we could throw in spirited.

Course you have lots of open, low traffic, roads up in your neck of the world. That may be more "4-6k" friendly than around here. If it's straight here it's got tons of traffic, and if it's not straight 4-6K will put you solidly in the ditch! LOL

To be honest Noah, from reading your post the last few years, I'd say your normal driving is pretty close to most others "Race" driving! LOL

I personally can neither confirm nor deny about headers.

ddombrowski

I can't speak for other teams, but a friend of mine had one of the bursch (I think) headers sitting in his garage for awhile that he never put on his car because he expected it wouldn't do much.

They ended up putting it on the car and beat their best lap at Daytona by 1.7 seconds over the previous year. Of course, there could be a lot of variables but they said the car felt faster. Keep in mind that at Daytona you spend a lot of time north of 5500rpm. I think it made believers out of them and now has me seriously considering one.

Now, that said, it just boggles my mind that people can manufacture headers (or any automotive component, really) and not have a dyno sheet to go with it.

marc abrams

Mike, while my experience with headers are a bit different. I had a 79 Z28, with a stock 350. With headers I lost a ton of torque between idle and 1500 RPM's. Now you may be asking who cares about idle and 1500 RPM's? Well I'll tell you, to get the car rolling from a dead stop I needed to rev it up to get rolling. With the manfolds, I could almost come off the clutch without giving it any gas to get rolling. I ended up putting the manfolds back on with true dual exhaust because I couldn't take the noise no longer.

V2Rocket

3 years ago I emailed Lindsey Racing for dyno info for the MSDS headers they sell.

They told me they didn't have anything and that I should contact MSDS directly.
I emailed MSDS directly asking for dyno info (since they have done testing for other cars they make headers for).

I am still waiting for their response...

ddombrowski

Yeah....

I went back through a few threads when the gen2 MSDS headers were announced. I saw a few claims from MSDS and thought 'wow, this was in 2015. Surely there is dyno data by now..."

Nope. I even saw a few replies specifically asking for dyno data that went ignored.

To me that says they either dyno'd and showed zilch difference (in which case they'd never publish the data) or they just didn't bother to dyno it. I'm not sure which is worse.

V2Rocket

They do claim a sizable gain in power/torque on early 928 models, and the 928 guys seem to like them.
So I am sure they work, but strange that a company won't spend $100 to dyno a car a few times with the headers installed as a marketing tool.

ddombrowski

I saw that claim, but again, how do you come up with a number like 23% and not have a dyno chart to back it up?

In my searching, I found this - http://members.rennlist.com/m758/944SpecDynoCharts.htm

While there is no 'back to back' comparison of stock/MSDS/Bursch headers, there may be room for minimal improvement but nothing groundbreaking. There is no clear trend, but there also isnt a lot of data. Keep in mind also that there are most certainly compression ratio differences between some of those dyno runs (83 vs 87 engines, different head shaving, etc).

One thing to note is that my friend who switched to the bursch header came from an early cast manifold, so that may be the reason for the improvement, as even the stock 'header' is a few HP improvement over the stock cast early manifold.