[dcook_14]

I have a D1SC in my car right now and am about to pulley down. I know that a D1 head unit with a 3.4" pulley will make more boost, ceteris paribus, than a P1 head unit with a 3.4" pulley.

My question (and it might be a stupid one), does a D1 head unit make more power than a P1 head unit at the same boost levels?

Anyone venture to guess what my boost and hp/torque numbers will be if I run a 3.4" pulley on my D1SC on a basically stock engine?

I have:
D1SC head unit
Procharger Red Race Valve
Procharger 3 core IC
42# Lucas Injectors
GT Fuel Pump
BBK O/R X Pipe

Bob thinks I'll be running 14-15 lbs of boost, which I think is about right

[B0B]

yup, the D1 usually makes slightly more power at the same boost level due to its different impeller design that flows more volume. i'll wait for others to chime in on this.. its worth a shot putting it on and thowing her on a dyno.. i'd do a pull to about 10 psi (regardless of RPM) and let off, see where that puts you powerwise.. then do a pull to 12, then redline (or what rpm you think your cutoff point will be) and see what she does.. with that 3 core and a good tune you should be ok if your engine is in good shape and you are running nice and rich 11:3-11.6 a/f ratio! i can see it putting down at least 450 with that pulley.. which could be safe as long as your IAT is cool and your AF ratio is good!

[B0B]

its your call on how hard you want to push it, but the centri is the safest poweradder on these motors especially when you have that nice big $1100 intercooler on there

[Boostang]

the D1 will make about 20 to 30 more hp due too its compressor design..

[06RedfireGT]

I would start doing stuff like longtubes, or cams to let the motor breathe better, and knock the boost down some while still making power.

[Boostang]

^^^ what he said! id do some exhaust work first then start with stuff like the plenum and tb. the boost will drop and youll make same power or maybe even more power with more reliability!

[dcook_14]

Originally Posted by B0B yup, the D1 usually makes slightly more power at the same boost level due to its different impeller design that flows more volume. i'll wait for others to chime in on this.. its worth a shot putting it on and thowing her on a dyno.. i'd do a pull to about 10 psi (regardless of RPM) and let off, see where that puts you powerwise.. then do a pull to 12, then redline (or what rpm you think your cutoff point will be) and see what she does.. with that 3 core and a good tune you should be ok if your engine is in good shape and you are running nice and rich 11:3-11.6 a/f ratio! i can see it putting down at least 450 with that pulley.. which could be safe as long as your IAT is cool and your AF ratio is good!

That's what I'm confused about though... Wouldn't the extra volume from the impeller design just be more boost?

If I can find a friggen tuner anywhere within 6 hours of me that knows what they are doing with a Mustang, then I would love a dyno tune!! I plan on running it on the rich side and I'm hoping the IC keeps the IAT down. How rich is too rich though? I've heard that if you run too rich that it can wash down the oil on the cylinder walls (IIRC that's what it does, maybe I'm way off)

Originally Posted by Boostang the D1 will make about 20 to 30 more hp due too its compressor design..

Again, won't more volume = more boost?

Originally Posted by 06RedfireGT I would start doing stuff like longtubes, or cams to let the motor breathe better, and knock the boost down some while still making power.

I'm prolly gonna do some LTs and cams next spring/summer.

Originally Posted by Boostang ^^^ what he said! id do some exhaust work first then start with stuff like the plenum and tb. the boost will drop and youll make same power or maybe even more power with more reliability!

So a car w/ 450 hp at 12# is more reliable than a car at 425 at 14# of boost? Is that just because of the decreased stress on the internals with lower boost levels?

[Eagle2000GT]

Every car responds a little differently. But, if I remember correctly, a D-1SC makes 5-6 lbs more boost with the same pulley as the P-1SC. I'm currently running a 3.7" pulley and making 8.9 lbs on my P-1SC. ProCharger said that for each 1/10" you go down you gain around 1 psi. Going to a 3.4" pulley would put my P-1SC around 12 lbs. I don't know but a 3.4" pulley on a D-1SC might be a bit much for the stock internals?

I have also been told that to safely run 425 rwhp you should have additional mods to help relieve the stress off of the rods and pistons. That you shouldn't try to get there just by upping the boost on a supercharger. The better the flow through the engine, the less stress on the rods and pistons. Long-tubes with o/r pipe and cams are a couple of mods that help the engine hold up to the stress.

There are motors that have run at 425+ for a couple of years. There are others that hold up only a few months. Most people suggest that the tune is the problem but it's just as likely that those that don't hold up are those that do not have other supporting mods.

[dcook_14]

So I might have just spent a bunch of money on a pulley I cant use... Sweet

I'm only running 6# of boost with a 4" pulley and I know the .1"=1# of boost thing so I figured I'd be running about 12# with a 3.4" pulley... IDK

[Eagle2000GT]

Even if you are only at 14-15 lbs of boost. That's quite a bit of power to be throwing at stock internals. One other thing, if you plan of pushing your motor to the absolute limit you've got to get a good dyno tune.

I read a post the other day from a guy who said he blew up his motor when the tempature got colder. He said he had a summer tune and the cold air made a difference. I don't know about you, but I have no intention of pushing my motor that far.

[Boostang]

yes 450 on 12# is way safer than 450 on 14#..
you want ur motor to be able too breathe as in let some of that boost flow out rather tan keep it all "back pressure'd" in..
summer tunes dont go well with winter tunes due too the humidity in the summer affecting most tunes.. so ur car in the winter will run differently than it did causing (sometimes) blow motors

[Scott2001GT]

so u need a cooler weather tune?

[Boostang]

yes..

[BLOWN2V]

Originally Posted by Boostang yes 450 on 12# is way safer than 450 on 14#.. you want ur motor to be able too breathe as in let some of that boost flow out rather tan keep it all "back pressure'd" in.. summer tunes dont go well with winter tunes due too the humidity in the summer affecting most tunes.. so ur car in the winter will run differently than it did causing (sometimes) blow motors

this is not true....
boost doesnt kill motors....boost is nothing more then a measurement of back pressure in the intake track and thats it it has nothing to do with flow or amount of air.... for example.... you take said car that is making 450 with 14lbs of boost... add ported heads,cams longtubes and intake manifold now said boost read 8 but power is 550.... is that 550 safer then say a car making 550 with 15lbs nope... its not the whopping 15psi worth of pressure that kills the motor, cause it takes the same force on the piston to make 450 n/a as it does to make 450 with 1psi or 1000psi of boost its still the same force on the piston n rod

another example in your way of thinking with cams n longtubes and such will lower the boost how does it lower the boost... it lowers the boost number by getting rid of restriction but it still the same amout of air if not more air getting into the chamber... thats why the boost number goes down and power goes up.. in no way will it bleed off pressure to make it safer...well unless you are running to big of N/A cams with a blower but then its not safer cause now you risk burning up the exhaust valves ... I know its something someone told you on the internet but it is just interweb BS

[BLOWN2V]

Originally Posted by Scott2001GT so u need a cooler weather tune?

no.... if tuned correctly the computer will adjust the timing and fuel based off the MAF and IAT.... but what you do need to watch is some parts of the country use a winter blend of fuel and if you are in one of those areas then just pull a 1-2 degrees worth of timing out but your tuner should tell you how much if any...

[BLOWN2V]

Originally Posted by Boostang yes 450 on 12# is way safer than 450 on 14#.. you want ur motor to be able too breathe as in let some of that boost flow out rather tan keep it all "back pressure'd" in.. summer tunes dont go well with winter tunes due too the humidity in the summer affecting most tunes.. so ur car in the winter will run differently than it did causing (sometimes) blow motors

the reason the run differently is because cold air holds more oxygen then hot air...

if the tuner is setting the tables right then you should have nothing to worry about cause the computer should pull n add the correct amount of timing and fuel based off of the MAF N IAT readings

[BLOWN2V]

Originally Posted by Eagle2000GT Even if you are only at 14-15 lbs of boost. That's quite a bit of power to be throwing at stock internals. One other thing, if you plan of pushing your motor to the absolute limit you've got to get a good dyno tune. I read a post the other day from a guy who said he blew up his motor when the tempature got colder. He said he had a summer tune and the cold air made a difference. I don't know about you, but I have no intention of pushing my motor that far.

most times its not the cold air as much as its the tune and placement of the IAT and winter blend of fuel,, when you mix that it can be real bad combo....... in colder months if you want to take it to the track and beat it around town then add a couple of gals of unleaded race gas and you should be fine

[dcook_14]

So... 450 hp at 12# of boost is not safer than 425 hp at 14# of boost?

Where's the best place for the IAT? haha, I guess a better question would be What is the IAT? I think it's the thing that comes off of the plenum and connects to your intake tube but I'm not sure.

If this is true, it means I just bought a couple of pulleys I'll probably never be able to use until I go forged... if that ever happens

[Boostang]

IAT= intake air temperature..
its not a sensor

[BLOWN2V]

Originally Posted by Boostang IAT= intake air temperature.. its not a sensor

yes it is a sensor....

the 96-00 have a seperate sensor where the 01+ have it has part of the MAF... and the best place for it is after the blower about 6inchs before the TB so the computer can read what the incoming air temp is... most kits have it routed to the power pipe which is not a good way to do and a good way to blow the motor with temp changes

the computer needs to see the incoming air temp to adjust timing and fuel correctly.... if its before the blower its going to read the outside temp and not what the real temp going into the motor is... the blower will heat the crap out of the air... if you have a intercooler it still needs to be after the intercooler and before the TB