komp55

Pretty disappointing. I went back to the dyno today to see what gains, if any, the addition of my Evosport shorty headers would make to my otherwise stock car. The headers have been on the car for over a month now.

Using the same dyno, and all else being identical to my prior dyno runs other than the intake air temperature being 4 degrees warmer outside today, I got a peak gain of only 8HP at 5,300 RPM, while peak torque actually declined by 4 ft. lbs. Peak torque remained at 3,000 RPM. My car is now producing 434 RWHP and 491 ft. lbs. of torque, so I am still very pleased overall.

Perhaps others have gotten better results with just the addition of shorty headers, but I'm not one of them. I seriously doubt if shorty headers alone will actually bring anything close to the 20 - 30 RWHP I've seen claimed here. This one ranks as my second worst performance "enhancement" in terms of cost per each HP gained, the worst being on a previously owned car.

What's my next step in the quest - TB or pulley?

SteveFox

Pulley next for sure.

Depending on where you live, you should get some minor cooling mods(spacers, new pump, -10* mod, and 160* stat). All inexpensive and effective as a unit.

ROCKETW19

I was never a beliver in the crazy gains people said either. I remember 30 rwhp quotes. I would bet 12hp for shortys.
the good news is your car is/was strong from the start. my car dynoed 401rwhp stock you have a 30hp head start.lol

ROCKETW19

Oh ya, next mod for sure pully and ECU. that will also make your headers work better. then after you add TB. your headers will be workin to their fullest.

psk145

did you feel a difference on your butt dyno?

I can definitely feel a gain on the set I had made, but I havent had time to dyno it again.

LTHL VPR

I dyno'd a set of shorties on my stock car and saw no increase as well. Not too surprising though as headers don't usually see the gains on forced induction cars as you would see on naturally aspirated cars.

ROCKETW19

headers IMO shouldnt be added first. there is no need for them untill you do TB and pully. you will see gains after that for sure but I still dont belive the crazy number people quote.

komp55

Yeah, and I learned my butt dyno was wrong. After the header install, it felt like low end torque (below 2,500 RPM) was down. In fact, the dyno shows decent gains in low end torque with the addition of the headers; e.g. +11 ft. lbs. at 2,500 RPM. The upper RPM range feels like the engine is less restricted, but the power gains measured didn't seem commensurate with the feel of the butt dyno. Either way, the car seems more eager to accelerate with the addition of the headers; they just didn't create gains as large as I had been led to believe I might obtain. Definitely dyno your car and share your experience.

ROCKETW19

psk145s results will be better than yours due to the fact he has a pully. your letting your motor breath better but first you need to give it a reason to breath better (TB, pully)

phatmitzu

Get rid of your primaries and let it breath.

Vadim @ FD

On the car with pulley and tune, the headers make a nice 20-25RWHP gain. On a stock car, stock manifolds are OK.

I will going through of these bolton again on Jangies E55, will be able to see all of the gains, part by part.

jangy

I'm expecting to get slightly better bottom end and hopefully about 20hp. Anything more is butter.

komp55

Yep, that's my plan too. Measure the gains produced by each add-on. I'm thinking pulley is the next project.

dyno

I think result is not bad, considering that only difference is because of some steel curving ..: quite same primary pipes diameter and stock outlet port.

I got the idea that, other things equal, benefit comes even from larger pipes' dia.
therefore VRP's that I think have a 1.75" diameter should do better ..

NGS_E55

Even at 20hp, have you guys done the $/hp? I am considering discounted headers and even at a discount, it doesnt seem so appealing.

higginsbeach

I have the same headers but had them installed with an 80mm Throttle Body and it kicks ***. Get the TB and you won't be sorry. As it was explained to me, you have more air that can go into the Supercharger with the headers, now you can force more air into it with a TB. The two can together quite nicely and than an ECU tune to tie it together for more HP....TB is an expensive Mod but BOY OH BOY is sounds like a giant Vacuum sucking air into the supercharger........

jangy

From a $ analysis, you need to keep in mind that the headers should actually come AFTER you modify the intake. In that respect, you have typically already started to approach the diminishing returns. By contrast, look into $2500 for an easy 50 (HP and TQ) with the pulley and ecu.

On a forced induction, why open the back end when the front is tight? You only put in as much air as the screw and other associated backpressures allow. The headers basically come into play at the top end, when the screw is really being more of a restriction than a help. The headers help to drop the localized pressure, and therefore increase the airflow. On a dyno chart, I would look mostly at the HP curve to be more linear, rather than plataeuing out.

EVO Headers are nice. You kind of twisted it by getting them first, but they are still nice. Just add more bol on toys and you will be happy.

E55 RUSS

My car made 535 HP at the crank with just shorties...

jangy

At the crank? Did you measure or are you "correcting"? What was it at the wheels?

E55 RUSS

It was my 1st dyno ever...on Dyno Dynamics and machine calculates it self...I know its not right but everybody measures here crank HP...

jangy

Do you know the wheel numbers? It would be interesting to see what just shorties really adds to a stock car on the dyno. I'm not so sure that the gains can really be captured that way, but just curious.

komp55

See my original post. Just shorties added to a stock car. 8 RWHP.

jangy

Sorry bro, I was asking Russ, but didn't make it clear. i was just curious to see if he claims different numbers than yours. I dunno that we have any other data on a stock setup with just headers.

dyno

Russ probably had the popular chip tuning that gives 525 crank HP
.. so, shorties added 10 , or 8 at wheels.
seems correct.

jangy

What chip tuning that gives 525 at the crank? Sorry for the ignorance, but i have only recently begun to believe that anyone has a clue about MB ECUs.