Looking at low boost build - Input please!

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10-12-2010, 04:42 PM
Bigbadwhitey

Looking at low boost build - Input please!

I keep seeing builds for people in search for x.xx passes, however thats completely not the direction Im looking at. Im looking for input on a low boost setup, hopefully with avoiding touching the internals of the motor.

Goals for the final outcome would be a car thats really streetable, I have to drive this back and forth to school everyday, so drivabilty is key.
Something thats fairly tame untill the skinny pedal is mashed.
And not that hp matters, but soemthing maybe in the 375rwph range.

With that out of that way, what would be suggested? Through searching, 4-5psi would get me to my goals faily simply, but how reliable is that on an 82k mile motor? I have a local wrench shop that does all tuning on my brothers boosted lt1 (mind you its one of those x.xx cars) so getting a good real time tune wont be difficult.
Is there any inherant problems with buying a used setup, aside from possibly having to rebuild the headunit? Does anyone have an average figure on how much that costs?
Self contained units vs one id have to tap lines for, like a p600b?

I also already have a racetronix fuel system consisting of a walbro 255ho, boost a pump wiring and 42# injectors, do you think the injectors will be overkill?

Shredding belts. I know this is a going to happen situation, but whats my best bet to avoid this? Ive head going with a wide belt(?) will decrease my chances, but again not to sure what that means!

So in short, anyone running a stock interals, low boost, FI ltx, id greatly appreciate your insight!
10-12-2010, 05:25 PM
QC97Z

I'm not running stock internals...not hardly. But, I can do my best. I'm assuming by "internals" you're talking about the rotating assembly/ "bottom end".

A low boost build (4-5 psi) can definitely get you to 375 RWHP, and above.
My setup was bought used, and is in great condition. It's a self-contained Procharger. Not sure how much rebuilding costs, but buying a good used setup from a reputable person on here or LS1Tech would be just fine. I wouldn't worry too much about re-building the unit right away.
My setup cost me about $4300 if I remember correctly, but it's an F1A with FMIC, SDCE tensioner kit (12 rib belt) etc.
For simplicity (and less leaks to diagnose/chase) I'd go with a self-contained unit. I wouldn't bother with an oil-pan-tap unit.

Do you have (or are you planning on) anything done to the heads? Different cam? Or do you just plan on boosting a completely stock motor? With more free-flowing TB, intake, and heads, it will take a lot more volume to make 4-5 psi (therefore more power at a lower psi) than stock. Either way you want to go is your business, I'm just saying you can make more power with a stock bottom end if you have more flow/volume to burn.

I'm not sure about your fuel system...the single 255 should be alright, but I'm no technical professional as far as the power capacity one pump can provide for. I'm running dual Walbro in-tank pumps. I think the injectors might be a bit light, but I could be wrong on that as well.

As far as shredding belts, it doesn't have to be a "going to happen" situation. Mine's not. A system with a pulley upgrade (more ribs) is useful to prevent slippage, but shredding belts will depend on how well the supercharger's pulley is lined up with the crank pulley. Only a good quality product can achieve that from bolt-on brand new. If you buy a setup used from someone, they will (more than likely) have worked out the bugs already for you as far as alignment goes, providing that it performed well for them for at least a few months' time. Mine came with all the bolts, standoffs, shims, etc pre-labeled and I've been burning the tires off since.

Now it feels like it's CALL911's turn to weigh in...
10-13-2010, 11:25 AM
Bigbadwhitey

Quote:

Originally Posted by QC97Z

I'm not running stock internals...not hardly. But, I can do my best. I'm assuming by "internals" you're talking about the rotating assembly/ "bottom end".

A low boost build (4-5 psi) can definitely get you to 375 RWHP, and above.
My setup was bought used, and is in great condition. It's a self-contained Procharger. Not sure how much rebuilding costs, but buying a good used setup from a reputable person on here or LS1Tech would be just fine. I wouldn't worry too much about re-building the unit right away.
My setup cost me about $4300 if I remember correctly, but it's an F1A with FMIC, SDCE tensioner kit (12 rib belt) etc.
For simplicity (and less leaks to diagnose/chase) I'd go with a self-contained unit. I wouldn't bother with an oil-pan-tap unit.

Do you have (or are you planning on) anything done to the heads? Different cam? Or do you just plan on boosting a completely stock motor? With more free-flowing TB, intake, and heads, it will take a lot more volume to make 4-5 psi (therefore more power at a lower psi) than stock. Either way you want to go is your business, I'm just saying you can make more power with a stock bottom end if you have more flow/volume to burn.

I'm not sure about your fuel system...the single 255 should be alright, but I'm no technical professional as far as the power capacity one pump can provide for. I'm running dual Walbro in-tank pumps. I think the injectors might be a bit light, but I could be wrong on that as well.

As far as shredding belts, it doesn't have to be a "going to happen" situation. Mine's not. A system with a pulley upgrade (more ribs) is useful to prevent slippage, but shredding belts will depend on how well the supercharger's pulley is lined up with the crank pulley. Only a good quality product can achieve that from bolt-on brand new. If you buy a setup used from someone, they will (more than likely) have worked out the bugs already for you as far as alignment goes, providing that it performed well for them for at least a few months' time. Mine came with all the bolts, standoffs, shims, etc pre-labeled and I've been burning the tires off since.

Now it feels like it's CALL911's turn to weigh in...

What headunit would you recommend thats a contained unit for that low of boost?

At the moment I plan on keeping heads and cam the same. Being on a university student budget i was planning on doing heads and cam the following winter. I have a spare set of heads i plan on sending away to get opened up, and then getting a cam spec'd to match. The car already has full exhaust,and id plan on getting a 58mm tb and having the intake manifold opened up to match it.

So pulley allignment is the big monster in making sure the belts dont shred? I assume this is just achieved by machining the bracket or swapping out pulley to get ones that line up well?

Thanks for the info and help!
10-13-2010, 03:02 PM
RealQuick

P1SC blower is probably the best solution for simplicity.
10-13-2010, 03:11 PM
QC97Z

Quote:

Originally Posted by Bigbadwhitey

What headunit would you recommend thats a contained unit for that low of boost?

At the moment I plan on keeping heads and cam the same. Being on a university student budget i was planning on doing heads and cam the following winter. I have a spare set of heads i plan on sending away to get opened up, and then getting a cam spec'd to match. The car already has full exhaust,and id plan on getting a 58mm tb and having the intake manifold opened up to match it.

So pulley allignment is the big monster in making sure the belts dont shred? I assume this is just achieved by machining the bracket or swapping out pulley to get ones that line up well?

Thanks for the info and help!

P1SC is a good unit. It can be your solution for a low boost application, and will have enough capacity for you to crank it up a bit once you put on the better flowing heads/cam/intake/TB.

Keep in mind that in order to control boost, the pulley size must be changed on the S/C head unit. your maximum boost will also be determined at the maximum RPM you plan on turning the motor. For a stock bottom end, I probably wouldn't turn it past 6000 rpm.

Yes, alignment is EVERYTHING. There's nothing else that shreds belts besides alignment issues. Purchasing a complete kit from a) ATI themselves or an ATI dealer or b) used from someone that had positive results from their kit will help. Being meticulous when installing everything and doing your best to inspect alignment will also help. It's also good to have knowledge of machining, so you can decide WHAT needs to change in order to solve your alignment issues.

Quote:

Originally Posted by RealQuick

P1SC blower is probably the best solution for simplicity.

^^ Agreed with RealQuick.
10-13-2010, 03:28 PM
ZGOBYBY

Ehhh... Even with 5 lbs. of boost through a T60 Garrett turbo over one summer which ended up equating to about 1,000 miles of driving on my 85K LT1 motor, my motor is starting to have EXTREME amounts of blow by, and is now running like garbage. I ran Walbro 255, and 42 LB SVOs as well with my set-up. I will not run the car again until I build my other block I have for boost.

As for your fuel setup, I think it is fine for running a low boost F/I setup... it's kind of a standard setup from what I have seen.
10-13-2010, 04:25 PM
Bigbadwhitey

As it sits the motor never sees past 4k rpm, as it is mostly street and never sees the need for it.

ZGobyby how often were you boosting? Rather, at what rpm did the t60 spool at?
10-13-2010, 04:43 PM
QC97Z

If you'd never really go above 4K rpm, you'd need a pretty small pulley to see the boost you want at that low of an RPM.
10-13-2010, 05:52 PM
ZGOBYBY

Quote:

Originally Posted by Bigbadwhitey

As it sits the motor never sees past 4k rpm, as it is mostly street and never sees the need for it.

ZGobyby how often were you boosting? Rather, at what rpm did the t60 spool at?

Ummmm... It spooled up around 3700 RPM I believe. From a dead roll, the turbo wouldn't spool until 2nd gear.
10-13-2010, 09:23 PM
Bigbadwhitey

Quote:

Originally Posted by QC97Z

If you'd never really go above 4K rpm, you'd need a pretty small pulley to see the boost you want at that low of an RPM.

Id be ok with going with a pully that would get me the 4-5psi at a higher RPM, that way i would be at less boost durning regular driving, and potentialy increasing longevity of the motor?
I like the idea of having the power there when needed, But not using it when its not.

Edit: Also, will i need to run a BOV? And I know an intercooler is a good idea, but will it be essential?
I ask because ive found these ATI kits that appear to come without fueling systems or an intercooler, and a p1sc (id link but i dont think thats allowed?)
However, at 1800 more than most used kits cost, i dont know if this would be a real bonus. Tricked out toy is selling a kit on here, but I cant tell if its overkill as well?
10-15-2010, 07:21 AM
QC97Z

Quote:

Originally Posted by Bigbadwhitey

Id be ok with going with a pully that would get me the 4-5psi at a higher RPM, that way i would be at less boost durning regular driving, and potentialy increasing longevity of the motor?
I like the idea of having the power there when needed, But not using it when its not.

Edit: Also, will i need to run a BOV? And I know an intercooler is a good idea, but will it be essential?
I ask because ive found these ATI kits that appear to come without fueling systems or an intercooler, and a p1sc (id link but i dont think thats allowed?)
However, at 1800 more than most used kits cost, i dont know if this would be a real bonus. Tricked out toy is selling a kit on here, but I cant tell if its overkill as well?

Your first comment sort of ties in to your question about needing a BOV, or in the S/C world, a "bypass valve".

Yes, you will need a bypass valve. It works the same way a BOV does for a turbo. If you've been boosting, and you let off the gas, you need that pressure still left in the charge pipes to be released, otherwise it will push into the motor and create a fatal lean condition. I'm using a Vortech bypass valve on my setup.
"Regular driving"....well, under "regular" or "grandma" driving, you'll always be in vacuum, and any boost you're creating will expel into the atmosphere from having a bypass valve. When you step on the gas and open the TB (depending on how much), you'll reduce vacuum, eventually to zero, then you'll start boosting. So whether you have "power" or not kind of depends on you...What I'm saying is if you have the unit pulley'd for 4-5 PSI at max RPM (6000 or so), you won't see (or feel) much unless you're really mashing the throttle. And at 4K rpm, you may get like 3 psi max. Get a smaller pulley so you can be at 5 psi at 4K rpm. Then watch your RPM from there, or get some sort of wastegate that will expel anything past 5 psi. Then you could boost earlier, and ramp up the RPM however much you want and never exceed a 5 psi target.
An intercooler would be a good idea, even for low boost. ATI has Twin High Flow kits, or you could do a smaller FMIC custom on your own. I have a huge FMIC behind my front bumper. FMIC = Front Mount InterCooler.
Yes, most ATI kits don't come with fueling. For a low boost setup like yours, a Walbro 255 in the tank, stock fuel filter and lines, a fuel pressure regulator that will reference boost 1:1, and some bigger injectors should do (48#?). No fuel rail or line mods needed. I'm still running the stock lines, stock fuel filter, and stock rails. They're good to 700+ RWHP.
10-15-2010, 05:25 PM
Bigbadwhitey

Quote:

Originally Posted by QC97Z

Your first comment sort of ties in to your question about needing a BOV, or in the S/C world, a "bypass valve".

Yes, you will need a bypass valve. It works the same way a BOV does for a turbo. If you've been boosting, and you let off the gas, you need that pressure still left in the charge pipes to be released, otherwise it will push into the motor and create a fatal lean condition. I'm using a Vortech bypass valve on my setup.
"Regular driving"....well, under "regular" or "grandma" driving, you'll always be in vacuum, and any boost you're creating will expel into the atmosphere from having a bypass valve. When you step on the gas and open the TB (depending on how much), you'll reduce vacuum, eventually to zero, then you'll start boosting. So whether you have "power" or not kind of depends on you...What I'm saying is if you have the unit pulley'd for 4-5 PSI at max RPM (6000 or so), you won't see (or feel) much unless you're really mashing the throttle. And at 4K rpm, you may get like 3 psi max. Get a smaller pulley so you can be at 5 psi at 4K rpm. Then watch your RPM from there, or get some sort of wastegate that will expel anything past 5 psi. Then you could boost earlier, and ramp up the RPM however much you want and never exceed a 5 psi target.
An intercooler would be a good idea, even for low boost. ATI has Twin High Flow kits, or you could do a smaller FMIC custom on your own. I have a huge FMIC behind my front bumper. FMIC = Front Mount InterCooler.
Yes, most ATI kits don't come with fueling. For a low boost setup like yours, a Walbro 255 in the tank, stock fuel filter and lines, a fuel pressure regulator that will reference boost 1:1, and some bigger injectors should do (48#?). No fuel rail or line mods needed. I'm still running the stock lines, stock fuel filter, and stock rails. They're good to 700+ RWHP.

Awesome, thank you! The wastegate seems like a great idea but im confused at the difference between a bypass valve and a wastegate? A wastegate prevent there from being more than 5psi by releaseing air from the intake pipe preventing more than x ammount of pressure to build up? Where does the bypass valves it and how is it different?