24v p pump twins Big exhaust = less boost, am I crazy?

K

Kustum_kid

New member
This is my set-up.... .40 over 24v, industrial injection ported head, hamilton 188 cam, hamilton push rods, 110# springs, 180 p-pump conversion (pump has full cuts afc mods #5 plate), stock size lines and tubes, 7x10 (ddp 150's), steed speed manifold w/2 38mm gates (goal with the gates was to gate both front and rear banks of the engine even as possible and keep divide in manifold un touched) , turbos hx35 12cm housing w/62mm compressor wheel (62/65/12) over a borg s475 (75/96/1.32).
Ok, so I put all this crap together and it don't work at all like i think it should. Very smokey even at 75psi of boost and over all not very quick. So, I take the pre-boost screw all the way back and start to turn the star wheels back to take some fuel away... the more I take away the better it runs!!! Now I am not a diesel guy (only owned one for 8weeks so far) but from what I read more fuel more power? So, I mess with it a few days ajusting the gates and starwheel and I got it so I put it to the floor in 3rd gear @ 45mph it hits 80psi (untill it smokes my 35" tires lol) just a haze of smoke very fast feels like it going to break something in the suspention but I'm very happy with that..lol
So, truck runs good I figure I need some dv's so I ordered them. In the mean time I thought I would upgrade the exhaust system (had a stock 3rd gen 4in tail and miss pipes in the middle). To see how good the gains of big exhaust would be I took it all off (all but the downpipe) and drove the truck. It runs like crap!!! makes just over 60 psi slow and smokey. I did change the filters on my fass titainium at the same time which I thought of later that yeilded me about 10-15 psi more fuel pressure than before. Pressure was 30 before and close 45 now. Would that fuel pressue make that much difference? I decided to install my 5inch exhaust anyway since the other was junk anyway. My boost is now around 70 psi and it will clean up on top but not near as fast as it was with the small exhaust. Do diesel's like restriction like 2 stroke dirt bikes...lol???????????????
 
That's a mouthful. I'd say it's probably the new delivery valves, exhaust shouldn't make boost drop, but fuel would. Sounds like a good setup, just needs tuning. Too much fuel (smoke) will also put the fire out and make less power past a certain point.
 
I don't have the new dv's yet the only change to fuel was 10-15 psi increase in lift pressure do to clogged filters.
 
Have you checked to see at what PSI the AFC arm starts to move and when it is at full travel? What kind of timing are you running?

Like JQ says, serious tuning would make this work better.

Boost doesn't always equal power. With the head and cam, you can still see power gains with less pressure. The parts just start to work more efficiently showing less pressure and better use of the pressure there.
 
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have close to the same set up and im gonna tell ya right now fine tuning is the key ive been fine tuning for a while now and still not there its all trial and error.:bang
 
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