demetaktak

Hey guys. Today i had custom longtube headers installed and dynoed the car.
The car is runnin on 83mm pulley, 82mm tb, 2HE, 010 pump. Ecu/tcu tune, deleted cats and resonator.
Before the headers the car did 492 whp, 525 wnm 11.4 afr in 4 th gear.
Today with headers it dynoed 501 whp but a whopping 650 wnm in fourth. (750 wnm in third). Afr was 12.0.

But we lost boost. Before headers it was 14.5 psi whereas now it was 13.2 psi.

What do u guys make of it? Why such drought in whp gain ?

SterlingE55

You will lose boost with headers. Less restriction equals less boost. That's a huge increase in torque. What were your IATs?

Ls1toAMG

You have a pic of the dyno. Want to see the torque curve.

HeissRod

I think you are way too concerned with dyno numbers. You're constantly doing new pulls and asking about them.

kponti

What's the time frame between dyno sessions? What's the primary runner diameter of the longtubes?

demetaktak

here is the dyno paper.

ye i did 2 pulls, before and after headers.. honestly i couldnt care less of the dyno numbers, freeway is what matters to me, but this gain in whp looks too small.

the AIT were 15C on the start of the pull and aroudn 60 at the end..
bare in mind the pull was done in 4th gear and the dyno cut off @ 5300 rpm.
but still, 3rd gear was even less power even though it spun 7000 rpm flat.

i lost about 2psi of boost. is that much normal. tbo, i was expecting something like 0.5 psi

we all making a new crank pulley now, to get back those 2psis.
and one more thing, i have about 100wnm difference between 3rd and 4th. that normal?

demetaktak

and these are the custom built headers

demetaktak

,

Crissus

Have you adjusted the tune after headers? I always thought this has to be done. The Torque increase is just WOW. And Torque is what matters the end of the day. HP is just a calculated number based on Torque. How does it feel for you on the street? More powerfull?

Also your numbers are good for just the 83mm Pulley, Imagine you doing 180mm crank equivalent total, i bet you reach 550WHP after a good tune

demetaktak

i think that i dont really need a tune.. the AFR well close to perfect. in third gear it was 11.5 minimum and in 4th 12.0. the fourth was 0.5 leaner at any given time, is that normal?

it feels lot stronger, and faster, had a little incident and ended up evading the police,

but today, when i went back to the highway to get logs. the supercharger size of the crank pulley came clean off! in the morning before the run, there was like 5mm space between the 2 lower pulley, but i paid little thought to it and got the result. so i am guessing yesterday on the dyno, the pulley was not fixed well, hence the boost loss...
i opened another thread on crank pulley size to get 15 psi, but i ll ask here as well.
what pulley size do i need to go in combo with 83mm sc pulley and get about 15 psi?

Hulk

Boost is relative to restriction. You take off restrictions like the manifolds and replace with headers that will lower boost and make power. Boost will also add heat, that blower could become a heat pump. If it makes more power with less boost that is a very good thing. You seem fixated on this 15psi of boost.

demetaktak

i get that its not the boost that matter, but the airflow.. which i have now with the headers... but i got lot less power than i was expecting... i was thinking i would get around 530ish.. maybe a little more.
that is why i wanna get more boost, to get even more flow, coz now i think the car has much better outflow, headers, than inflow from the charger... and its cool enough for now, the timing is not pulled and the ecu is not dumping gas to cool things, hence 12 afr... i think i can squeeze more power out of it with a little more boost... and if thats too hot, i can always install killer chiller or water injection.