TxDiesel007

This is a very valid point....

unless of coarse you are on a dyno....

Rick

gunracer1

i can run 50#s of boost in 3rd gear real easy at say 3400 rpm. and hit 55#s in od at 75mph or so, maybe more. i have 3 pop off valves welded in the intake side of the cold piping and they blow open at 50 psi. i have the fuel cut back on the bottom to keep the smoke low and fuel miliage up. but i run a looser conveter than most and it keep the tubo lag at bay. this is all on my 98 2wd with a auto, a set of ddp stage 4s with a cut plate, a hx40/16 over a big bht3e.
and i have a head getting the full massage up in kanasas, ported out, o ringed and all the fancy coatings. i will dyno before and after to see exacty what the differance is.

RowJ

GR1 - Even with 3 POV's you can't hold boost at 50 psi??
Have heard this problem before... just seems hard to fathom!
Read elsewhere that twins under 50 psi get real smokey and laggy, but seems almost impossible to do it anyway.

I have no personal expirience with twins, other than lots of reading and future plans, but it seems the answer to 12V's question is... No, you can't set twins to stay under 50 psi and work well. Agree?

Even BD's smallish twins... with two S300 turbos... seem to jump to 60 psi with anything over 450 hp.

RJ

12valve

how about 6 blow off valves???

Send the head to usa, for Oring is one of the worse things... cant i buy an Oringed head?

ratsun

_________________

Call Piers he sells new 12v heads and can prep it any way you like and ship it out to you

Mike Holmen

If you put in an aftermarket cam and a max out hogged put head, you'll drop you're overall boost numbers and improve you spool-up. With the BD twins I wonder how much hot air is put out when you running 60psi of boost and how much drive pressure you have to push that amount of air. The BD twins spools fastest of any twins that I have drove. Even with my twins at wot, I still have a haze with my box at 3X3. The intial spool-up is sluggish but after that its pretty sweet ride. I still haven't tryied out the 5X5 except on the dyno.

gunracer1

i have my hx 40 wastegate opening at 20 psi, i think it would lower over all boost to set it at 15 or so but i think it would make it feel more like a 2 stage set up. right now it is just nice and smooth building boost, the pop off i used are small, from the grainger catalog. they are adjustable to 150 psi or so and cost about 7 bucks each. i think for a 50 psi twin system i would go with a hy9 with a modded internal waste gate and a hx 55 with a wastegated housing that was also modded for more flow. i still think this would be the ultimate towing set up for a stick or auto.

gunracer1

ok i did some checking at lunch, i can hit 50 plus psi in 2nd gear on the street at 3200 or so rpm. it is hard to watch the gauges when the truck chucks sideway[i just listen for the popoffs to blow]. no idea what it will do in first, the tires just get blown away.

12valve

ok... i found myself askin a guy at a CTD performance shop over PM to help me with the o-ring specifications, he was more then willing to help, couldnt belive it,
and a good friend at the shop, near me can do it for me that is... good.

next thing, do i still need head studs once o-ringed? they are sooo much dinero$$ keeping boost around 60

and what head gasket?

thx

BigBlue

Definately get the studs. The studs and o-rings will make your head gasket all but invincible.

fordsux8269

If it was a budget situation I would get the studs 1st the have it o ringed later on if needed.

RowJ

Agreed! You can do studs w/o o-rings and increase your saftey margin.
I'm not sure the same can be said about o-rings w/o studs ???

RJ