bstudey01

Just curious what kind of boost you guys are seeing with big crank pulleys and headers/open exhaust. I'm running 178 Evotech lower with the smaller S/C pulley and belt wrap kit. I have MBH headers and no cat's. I'm currently seeing a max of 27psi from the map via Dashdaq, which I think is about 12.5psi after figuring barometric pressure in my area. Does this sound right? I thought 11psi was stock? How much do you loose with headers and more open exhaust? If others with similar setup could chime in on what kind of boost they are seeing. I beleive my setup to be similar to a 185-190 crank pulley. Not sure if there is a problem or this is normal. Maybe a leak somewhere or slipping S/C clutch??

urbamworm

I saw 12.5 recently on one run, 12 on another and 11.3 on one other. I have Kleemann headers, no cats, x pipe with aftermarket mufflers with a supercharger pulley. It will vary with weather though. I believe you should be around 15.

bstudey01

15psi is kind of what I thought, although GregMB posted on a stock pulley and MBH's he was seeing 9psi. So I would be +3.5psi boost from that. Gotta get the girl back to the dyno/track since the new s/c pulley to see for sure.

AMG E Power

please do ! I really want to know if the upper pulley is giving the 2psi everyone says.
Ive never actually seen a before and after dyno.

adianaty

You may want to specify a steady state range since on my car with a 180 and the smaller upper, I can spike to 16.5psi after a shift but climbing through the rpm range it will drop. As such, I would consider mine at 15psi and I have headers and a 90mm TB. Also if you are using the dashdaq with the external sensor I would trust it more than what you get from the OBD port. I think your boost is right for your mods.

Forrest Gump 9

I have 180, small sc pulley, custom long tube headers, no cats, and 90mm tb and I see a hair over 14psi in third gear.

shardul

iTrader: (1)

They way in which the bypass valve is controlled by the ecu remap also influences the max boost you will see.

Hulk

Shards is right on the bpv also max boost will be in 3rd gear on the street and as Ali said look for steady instead of spike and have a real boost gauge instead of the obd

bstudey01

Could you explain further about the bypass valve?? Also could my stock map sensor be getting a bad reading. My car always seemed a bit slow to me at the track, best was a 11.49 and 120mph is the fastest I've gone, this was a cool day with ice in trunk tank and aits were only 80 degrees by the end of the run, so definately no heat soak. This was without the new smaller S/C pulley. But I have seen many others with same mods doing about 11.2 at 125 or so. I thought possible head gasket leak?? But no signs of it at all in oil, coolant, or exhaust.

Hulk

The tuner can control the bpv example opening sooner etc, every time it opens it bleeds off boost

Btw, just because they got best times doesn't mean you can't either...

Track prep and DA makes a big difference as well

e55amgrocket

With the 195mm I would see spikes over 15psi but usually in the mid 14's. That was with ported heads and all the normal bolt ons.

Denroll

I have a 175 lower, smaller upper, MBH headers (no cats on this run), ported heads, and the belt wrap kit. Boost sensor is in the surge tank feeding into a DashDAQ. I have logged at the track in pretty cold weather and showed 17psi.

I did a log a few days ago, but haven't looked at it yet (Yes, I am retarded). Mid-70's out at the time. I will check it out and see what my boost was at.

FinanceMike

If you search my threads I posted a before and after dyno (same day, same dyno).

Going from an ECU tune to a sc pulley and box tune I picked up 7whp and about 20wtq.

Not very impressive. Adding my Kleemann headers is where most of my power came from.

Denroll

^Probably a lot of power to be squeezed out of that box tune then.

PACougar

You my friend need a dyno tune.

E55Greasemonkey

I'm seeing max boost of 11.3lbs. Highway driving @ 82F, with mods listed below.

FinanceMike

I am a numbers guy. I wanted to see what each mod did on the same dyno under the same conditions. I dyno'd the car after each progressive mod.
Stock
ECU Tune
SC Pulley with box tune
Kleemann Headers with box tune
Dyno tune from Jerry.

The final dyno tune made a substantial difference. But going from an EC ECU tune to an EC SC Pulley box tune, I picked up 7whp and 21wtq

HeissRod

Did you go from an EC box tune to a SC pulley with box tune or did you go from a EC dyno tune to a SC pulley with box tune?

urbamworm

My guess is he went from a box tune to adding a supercharger pulley and not adding even a supercharger pulley box tune but running the supercharger pulley on his original box tune. There is still power to be made though, I gained a lot going from a supercharger pulley box tune to a dyno tune on the supercharger pulley.

chawkins2001

12.8lbs max here with a 190mm, no upper.

jmb614

14.1 is the max I've seen, usually see around 13.5 at the bottom of third however. 185 pulley, no upper.

bstudey01

Hmmm, that's closer to what I'm seeing. I wonder why such a difference between cars with the same basic setups?? Guess it really doesn't matter anyway, what matters is how fast she gets down the track. Can't wait to give her another shot with the new mods, plus I've been putting some effort into trimming some weight. Lighter rear wheel setup and evosport rotors too. Should have dropped about 100lbs of unsprung weight right there.

e55amgrocket

I've always wondered the difference myself. I think the best way to see the actual boost is with a true boost gauge from my experience. When i would see the sudden spikes i wondered if that was just a glitch from the MAP reading. On the dyno with a mechanical boost gauge the most we seen was 12.4-5 PSI using a surge tank i borrowed from Blackbenzz with a port on it for boost. That was with the 195mm pulley

chawkins2001

Yes mine was on the dyno too, 3rd gear pull too.

Denroll

I'm calling bullsheeeit on myself. Turns out I only saw 16psi. Here's da log: