My90Iroc

I'm trying to plan a motor build which I would like to complete by this time next year. I was gonna go N/A but it seems people are making too much power in street driven cars not to put a blower in the car. So now I'm starting to figure out what I'd need for a Procharged 355/6 spd setup. My question is about the blower with a sixspeed.

I think I know the difference between a surge valve and blow off valve where the surge is vacuum controlled and stays open at low rpms where the blow off opens under high pressure when the throttle blades close. With my manual tranny I like to downshift when slowing and even when you just let off the gas the motor stays wound up because it's being turned by the drive train, but the throttle blades are closed.

My question is what setup would be wise to use with the manual tranny so I don't hurt the blower under these conditions, surge valve, blow off, or both?
I'm thinking the blow off valve might be a better idea and I'll just always have a little bit of boost running through the motor, but if that's the case approximately how much boost would be going through the motor when just cruising on the highway with a 12 psi pulley?

My next question is about prom tuning for such a motor. Since it will be a completely new motor (currently have a 305) I'll have to start from scratch so what would be the best approach to take in tuning the car? Tune the motor N/A to get it running, put the blower on, then tune it again? Or, tune everything at once?

Sorry for the length but the help is greatly appreciated.

CrazyHawaiian

I've only seen blow off valves on intercooled F/I setups. So if you're going to intercool your setup then you'd probably end up with both. If not, then you'll have a surge valve. Either should be able to handle driving with a 6 speed. I dunno about Prochargers, but with my Vortech setup (10# belt) I dont see any boost when cruzing on the freeway. Unless you put load on the engine you'll be in vaccum. If you went WOT then you would build boost, but not while cruzing. As far as tuning, it'll depend on how you want to do it. Theres alot of ways to go about tuning your setup. Again, I dunno about Prochargers, but the Vortech setups come with FMU's that work with your existing ECM. These types of hardcoded 'boxes' work good with stock motors, but as soon as you start to change the internals of the engine they dont work as good. Sounds like you plan to do some mods to the engine (355 and all), so you'll probably want to go Standalone/DFI. You can choose between expensive standalone engine management (does all the tuning work for you), or you can save money and get creative with GM equipment, burning your own chips and such. It will depend on how much you want to spend and how much you're into it. If you decide to go standalone, then tune it all at once. If you stick GM then do it in stages (get the N/A 350 running first) so its easier to troubleshoot.

My90Iroc

I should have clarified, I will have an intercooled setup. To me the extra money for the intercooler is worth it to get more power and not have to worry so much about detonation from high incoming air temps.

I will be building the motor from scratch so I'm planning to use a good flowing intake (HSR looks good right now), AFR heads, and a cam that will work nicely with the blower.
I was hoping that it'd be possible to have a prom tuned for the motor and maybe use something like the superfueler to get the blower tuned. Or even use the FMU setup the blower kits include with bigger injectors and have the prom tuned right so the combination of the FMU and bigger injectors should make up for the motor being more powerful then stock. Does any of this sound reasonable?

I was trying to stay away from DFI because of the extra costs and I'd like to use GM's computer if possible to insure proper operation of A/C, cruise control, emissions equipment (if I decide to go that way), and so on.

Feel free to flood me with advice and opinions because I'm trying to learn as much about this as I can, and I'm the type of person who loves to know exactly what's going on before I get into something, especially something like this that is so meaningful to me.

Thanks for the input.

CrazyHawaiian

The FMU's that come with the blower kits are tuned for the stock heads/cam/intake. As soon as you start changing these things, the FMU becomes out of tune. Since you do plan to change the heads and cam, you will have to go Standalone/DFI to get a good tune. There are alot of aftermarket Standalone/DFI setups out there, costing between $900-$2000. They cost alot but really make the tuning process easy. The cost effective method of tuning would be to stick with GM stuff. In this case, a 749 ECM with a custom chip. I'm going the GM route because it can get the job done for less than 1/2 the price of the other stuff. It will just take more time and effort to get it tuned right. Since you're starting your project early, you should start reading on up PROM burning and tuning for our cars. The stuff you learn can help you burn a chip for both the N/A 350 swap (MAF/165, or SD/730), and the blower later on (SD/749).

Willie

iTrader: (1)

I think I know the difference between a surge valve and blow off valve where the surge is vacuum controlled and stays open at low rpms where the blow off opens under high pressure when the throttle blades close.

Correct. The surge valve is open under vacuum and closed when in boost. The BOV opens only when a pre-determined pressure is attained. Typically, this pressure is slightly higher than the maximum amount of boost you're making.


My question is what setup would be wise to use with the manual tranny so I don't hurt the blower under these conditions, surge valve, blow off, or both?

I believe a surge valve should be used, irrespective of the transmission. This valve is an outlet for air that the engine is not using that the blower produces. Under vacuum conditions, that's MOST of the air. Without this valve, the intake tract between the blower and TB will always be under pressure, causing the blower itself to work harder. This creates more heat. I have empirical data that proves this, based on my two surge valves, the ability to control one of the two valves, and my air temperature gauges.

Using a BOV can be considered insurance. It will prevent compressor surge when letting off the throttle, which can damage the blower. Although I currently do not have a BOV, it is high on my priority list of things to do.


I'm thinking the blow off valve might be a better idea and I'll just always have a little bit of boost running through the motor, but if that's the case approximately how much boost would be going through the motor when just cruising on the highway with a 12 psi pulley?

With a surge valve, positive pressure in the ducting between the blower and TB is greatly reduced (or eliminated). On the other side of the TB, i.e. in the plenum, you're in vacuum at cruising speeds. You're in vacuum under light to moderate acceleration too.


....PROM.... Since it will be a completely new motor... I'll have to start from scratch so what would be the best approach to take in tuning the car? Tune the motor N/A to get it running, put the blower on, then tune it again? Or, tune everything at once?

It depends. If you're running an system that cannot "see" boost, i.e. MAF or one-bar SD, you should tune N/A with the possible exception being the spark advance tables. You will have to "subdue" (retard) total timing @ WOT unless, depending on amount of boost, intercooled, water injected, etc....

With the above systems, neither knows how to compensate for boost. So choose EPROM constants and tables values for an N/A application. When in boost, you'll have to decide which method to use to add additional fuel to compensate for the additional air. I only know of two methods: An FMU (yuck) or a Carroll Superfueler (my choice).

The only example where you'll have to tune an EPROM with the "whole package" is if you use a system that can see boost, i.e. a 749 ECM with a two-bar MAP sensor. I understand a two-bar sensor can be used with a 730 ECM with minor changes.

In a nutshell, I believe that is that, although I probably forgot some stuff.

Willie

itsjojo

I just signed up to give you some feedback on how my Procharger 600b works. You can use this to decide if its what you want. I have no experiencew with manual tranys and boost. I am running a 700r4 behind a completely stock 350cu in. Tuned port fuel injection. L98 engine in a 84 vette. Yes I got rid of the crossfire injection. I have a 600b procharger installed for about 2 years now. Intercooled, surge valve and fuel management unit. First off I only have a surge valve. It is used to quickly vent boost from your intercooler and hoses when the throttle plates close (foot off the peddle). I learned quickly when setting this up about not venting the boost when you quickly take you foot off the peddle. If you get any substantial amout of boost and let up on the throttle the the manifold drop to vacuum while the boost in the intercooler makes a very loud buffeting sound for about 4 seconds. I mean you know this isn't good. Reading your post it sounds like you might be thinking of keeping boost to the engine all the time. I don't think that will be possible at all! I didn't understand the characteristics of my procharger, until I installed it and saw it operate. You have no boost until you mash the peddle (wide open throttle). Highway crusing there is no boost. Throttle closed, you have normal vacuum. If you don't use the surge valve as indicated I think you will have a lot of problems.
Once I hooked up my surge valve the whole supercharger package came together! I might try to find a blow off valve to use. My thought is that I could attain more boost quicker with a higher psi pulley and vent off the boost on the top end. I found that the 2.9inch pulley I had on the unit was a 6 lb pulley. I ordered and installed a 2.6lb pulley (10lbs). Nice difference. I am taking it to the track Sunday to see what she runs.
As for tuning, the procharger is very easy to tune. I have a Mass Air Flow computer system. The Mass Air system is forgiving to performance parts and you don't have to keep burning new chips as with Speed Density. I put this thing on and hook up the surge valve and dial in the fuel management unit(FMU). If you looking for low cost I might advise you to check out the FMU Idea on the procharger. This is boost operated, the more boost you make the more fuel pressure is created and more fuel goes through the injectors. You simply set the FMU neddle to full rich for you first ride after the install and just dial out some fuel. I have an air/ fuel ratio gauge. This reads green (rich) at wide open throttle when I start to set the fmu. Make a few pulls and close down the neddle valve a turn to reduce fuel. make a few more pulls and so on .... I do this until the air / fuel ration gauge reads "Stoich" which is right in the middle of lean and rich. This Fmu simply doesn't even come close to altering the stock fuel pressure under normal driving. It seems to only alter fuel pressure at wide open throttle. That is the beauty of this system.
A little note on exhaust. I was very impressed with the procharger then I installed a full exhaust system . 1-3/4 headers, knocked out cat, borla 2.5 mufflers and y pipe. When I took this car for a ride I was blown away by the difference. I would estimate that 50% of the power was blocked by that stock exhaust system. So don't forget to upgrade the pipes!!!
If you have any questions further I will be happy to get back to you.
Jojo

My90Iroc

Thanks for the help Willie. I have a few more questions.

Can you explain how the Superfueler works and how you hook it up?

Can you also give some details about the Cog belt setup, it seems much better then the ribbed belt setups? I've also read in another post that the stock cooling fans won't fit with teh Cog setup, is this true? If so what fans are you using and how's that working out?


Thanks again.

My90Iroc

Jojo, thanks for the info. as well. It's always great to hear firsthand experience.
My main concern with the surge and blow-off valves is when I down shift to slow down and the motor revs to 2000 or 2500 rpm's with the throttle blades closed to help slow the car. I was concerned that this may build boost and hurt the blower because the throttle blades are closed. What are your thoughts as far as that goes?

Thanks again.

Brian

Willie

iTrader: (1)

Can you explain how the Superfueler works and how you hook it up?

Go to: http://www.carrollsupercharging.com

Then click on Superfueler. It should answer your questions.


Can you also give some details about the Cog belt setup, it seems much better then the ribbed belt setups?

I've now had this setup for 2+ months and have driven the car almost daily. You hear a lot of guys say that a cog setup shouldn't be used on the street. I have no idea why because I couldn't be more content. Not only is a cog setup more forgiving in terms of pulley alignment -- it seems that with a ribbed setup, ANY variance in alignment throws the belt -- but you get absolutely zero slippage (obvious). Having run both setups, I can say that there's no comparison. I wish I had converted to cogs years ago.


I've also read in another post that the stock cooling fans won't fit with teh Cog setup, is this true? If so what fans are you using and how's that working out?

It's true. The cogged belt is made in a very limited number of lengths, unlike the ribbed. With the ribbed setup, it's primarily made in one inch increments with many half inch incremented belts available. It's a different story with a cogged belt, in as much as you must design the pulley system around the belt length. With ribbed, it's the opposite. The only belt length that will work on our cars is 1600mm long. With this, one of the three idlers used with the ribbed setup must be eliminated. The "third" ribbed pulley actually diverts the belt away from the primary fan motor. With the removal of this pulley on the cogged setup, the fan motor is smack dab in the way of the belt, so.....

I removed both factory fans and installed a 2500 cfm Flex-a-lite dual fan setup with shroud (Summit). I have my concerns as Flex-a-lite states these fans can support 250 hp. So far so good though, even in temperatures approaching 100 (it was 99 in Tucson yesterday, 05/14/03). But be it known that from my single intercooler days (two years ago) with a hotter running engine, I retained both pusher fans. With these, I've had absolutely no problems so far.

Willie

itsjojo

Brian,
Good question. First off remember that vacuum in the plenum or manifold opens the surge valve. If you foot is off the gas pedal any extra boost generated from a downshift motor reving will bow out the surge valve. I had the same question. If you down shift without a surge valve or it not being open, you will get the loud buffeting I mentioned. This can't be good. I tried to down shift and watch the boost gauge several times after I did the install. I have a vac/boost gauge with vacuum scale on the left and boost scale on the right with zero at the top. At idle, foot off the gass the vacuum registers 16 to 18 (vacuum). As I press the gas rapidly, the vacuum reduces 15, 13, 10, 5 0 ...etc, towards zero then the needle keeps moving further on the boost side showing the pressure increase of boost 1, 2,3,4,5, etc. At 50mph foot off the gas, the 16-18 vac reading is the same as if you were parked ideling. At that 50mph If I down shift into second gear with foot off the pedal, the the blower will push the extra boost out the surge valve which will be open due to the vacuum in the manifold and plenum. It is important to route the vacuum line to the surge valve to the plenum behind the throttle body and not to the intercooler tubing. The surge valve wants to monitor the boost/vacuum in the manifold. If I am crusing, foot lightly pressing the gas at 50mph the surge valve might be slightly open, doenshifting into second gear will send boost either go into the engine or out the surge valve if it is in fact open. This is all ok! The thing you may not be aware of is with a 6 psi system on a procharger 600b like I have, the boost seems to accumulate through all 3 gears. I thought the boost would hit 6lbs in each gear on the way up to 3rd. I was wrong. this is why I just installed the 10 pound pulley. Even with this 10lb pulley the boost does not hit 10lbs in first gear. Maybe I neeed to wind the out the rpms a little more. I beleive it hit 7lbs in first gear. I have only hit 7lbs with the new pulley since I only drove it twice since. I will say the if I accerate in first gear and then pull my foot outta it that damn surge valve makes me sound just like a tuner!!! lol "PFFFFFFFFFFFF" Real Loud! Kinda kool! The surge valve is louder with the 10lb pulley installed than the 6lb pulley ever was. Look out tuners!!!
Keep in touch! I will try to help you with any other questions you may have. I like trouble shooting these things!
Jojo