jangy

So, in the process of building two OUTRAGEOUS exhaust systems. Why outrageous, because they are our design . Anyhow, running into a few sticky points that I hoped experience could help on. One is I am running the HEM from Vadim, and like it. nIt is much more sturdy than the headers and gives me nice top and sound. The thing is, if I am going custom exhaust, what about the primary cats? If they get modified, then why not long headers? Crap....

dyno

if your Street use of the car is at least 50% .. I would not go for long headers that give the best on top end, in a racing environment

Yacht Master

jangy,
The HEMs are just fine. At this point I would not build my self away from a turbo install by replacing the HEM with long tube headers.
You said outrageous, Victor and Vadim have mentioned the possibility of a blow through turbo set up.
Jangy you could be the one.

Exotic-metal55

I vote,,,,,Long tubes and high flow cats!! You make plenty of low end tourqe and still will.

Any info on how much long tubes wil drop our IAT`s?

bobgodd

I vote long tubes as well. The slight drop in low end torque is more than compensated by the increased high end power. Plus, the car already has more than enough low end torque; you should still be able to fry the tires at will.

rflow306

From my experience long tubes on an e55 make very little difference in power. They do a better job at lowering egt's which is a plus.

bobgodd

Can you go into detail on some of these experiences? There seems to be a lack of consensus around here regarding this topic and it would be nice to get some finality.

rflow306

I tried a set of super-sprint long tubes first and made a little less horsepower about 2 rwhp, so I would call that a wash. Then I tried a set of custom long tubes with close to 1 7/8 primaries, lost some bottom end torque and picked up about 5 rwhp on motor. The biggest increase came on the nos where it picked up 10 rwhp.

I ended up going back to my Klee style shorties because the long tubes where to loud for my taste. I could also feel a slight resonance under the floor board when taking off in first gear at low speeds.

Vadim @ FD

Long tubes work well with bigger cams and ported heads.

The problem is passing smog for most owners depending on the state.

Jangy, I have a car with long tubes in the shop, you can listen to it.

Hammer Down

Let's hear it!

jangy

Nah, I'm not interested for sound. I want performance, and yes, I want it street car. This will be my daily driver now for the next few so I need to pass smog. After lots of talk, it seems that we will go with the HEMs and keep the primary cats. I want to cut the secondary cats and play with the mufflers. BTW, after a few days of driving with the HEMs, I am noticing sound, too.

bobgodd

Not to be argumentative but I'm having a hard time grasping this. Underneath that MBZ engine cover is a V8, much similar to any other small block V8. It has cylinder heads just like other V8's that need to breathe. The engine as I'm sure you know is a giant air pump, which is why intake and exhaust mods do so well. The stock manifolds are terrible and I really see this healthy V8 opening up nicely once it's allowed to exhale.

chiromikey

our s/c'd motors are not as picky about exhaust systems when compared to a n/a motor so i thoroughly believe what albert is saying about the headers he tested. on the other hand, i'm not a fan of supersprints product and imho there are other long tube systems that would have shown better results in his tests.

bobgodd

I understand that forced induction engines react differently to certain mods than N/A engines, but all these Paxton supercharged Vipers and the KB Cobras are seeing very good gains from headers. One would think that a S/C'd car that moves quite a bit more air than a N/A engine would definitely need the better breathing... que no?


I should also add that I'm not calling him a liar by any means. It just doesn't follow at all that anything "better" than the stock manifolds will only make 2hp, unless the design is flawed in some serious way.

chiromikey

ok, i think i see where the miscommunication is. i believe (and albert can correct me if i'm wrong) he was comparing supersprint long tubes to mid length/shorty headers rather than supersprints to oem exhaust manifolds.

E55 RUSS

I had shorties then removed Primady Cats and and installed straight pipes, the car defialy felt faster on TOP...Cory Kleeamnn says those Cats worth around 10whp...

psuball1

I just had my exhaust modified this weekend. I did it entirely for sound. I do feel a bit of TQ loss but the car does pull much smoother. Anyway, the car sounds AMAZING!! I planned on putting up some sound clips but did not have the chance this weekend.

I went to Meineke muffler in Pacific Beach. The owner worked on a race team and is very knowledgeable with exhaust modifications. He cut the mufflers open, took all the fiberglass out and cut all the baffles out of the system. The car sounds like a high-powered motor boat. The best part is that all the work cost me $360.00

CyE55

Just out of curiosity.... If you guys are spending this much money on modding a street car, why not buy a track car and the REALLY go NUTS !!!



A bit of a hijack, but just curious.

stevebez

The HEMS for turbo blow-through application would not be ideal as you need small diam primary tubes to keep exhausst velocity up to spool the turbos, better larger primary tubes will slow airflow to much and increase lag...

The Evosports would mbe work better here if you were to go to a turbo blow over.

Murtaza

If he cut all the fiberglass and baffling out...why not just staight pipe the mufflers? Or is there some sound supression still being done by whats left of the muffler..?

rflow306

100% correct, thanks Chiro.

Sorry, I did not make it clear. I was comparing a good set of klee style headers that were on the car to long tubes that I tried. The stock manifolds are very restrictive and should be changed the minute you start modding. You an expect an increase of 30 to 40 rwhp by changing to a good shorty /mid header.

komp55

Maybe on a modded engine; ot on an otherwise stock engine. More likely, you'll only get around 12 - 18 RWHP. It's been awhile, but I recall my Evosport shorties only added about 14 RWHP on my otherwise stock car (same dyno). Agree on the notion that almost any shorty header will be an improvement over the factory manifolds.

psuball1

It does keep the drone and sound out of the cabin gutting the stock mufflers. Also, if I was to do straight pipes I would have to get some other tips and I don't like any tips aside from the stock setup.

Murtaza

Need video clips, I want to hear that beast

Zod

There is one little tid bit of info we are missing here, the klee headers remove the primary cats, not sure if they replace them with their own though or just remove it. Primaries removal alone have shown gains of 7-10whp reported by some members.
thats where the rest of the hp comes from