jamie furman
Enthusiast
Since any and all air comes in through the throttle bodies that doesn't make much since does it? I guess the viper plant will have to hire your buddy to redesign the intake.
Question for Supercharging Gurus
- Thread starter jamie furman
- Start date
Daffy
Enthusiast
Kid,
The supercharger works to create boost in the intake manifold, to create that boost it's jamming the air into it. If you have a boost gauge hooked up to the manifold you can see the pressure go from vacuum off throttle, to boost on throttle & load. To get that boost the whole intake is pressurized, so .. no there wouldn't be areas where air wasn't getting - if you're getting boost then the whole intake is under boost.
If he was talking about the nitous, I'd give him more slack. Some intake designs can make for poor dispersion in the intake and not all cylinders getting fed the same.
Gerald, may be right, could be a case of boost envy.
Dave.
caveat: I've not supercharged my viper, but I've supercharged 4 of my other cars, so the above is just my general opinion. I'm sure others with exp with viper s/c's can shed more light.
The supercharger works to create boost in the intake manifold, to create that boost it's jamming the air into it. If you have a boost gauge hooked up to the manifold you can see the pressure go from vacuum off throttle, to boost on throttle & load. To get that boost the whole intake is pressurized, so .. no there wouldn't be areas where air wasn't getting - if you're getting boost then the whole intake is under boost.
If he was talking about the nitous, I'd give him more slack. Some intake designs can make for poor dispersion in the intake and not all cylinders getting fed the same.
Gerald, may be right, could be a case of boost envy.
Dave.
caveat: I've not supercharged my viper, but I've supercharged 4 of my other cars, so the above is just my general opinion. I'm sure others with exp with viper s/c's can shed more light.
Kid97GTS
Enthusiast
Thanks for explanations - my prior experience is solely with Weiand type blowers on old Chevys - I guess it's a little easier to imagine the charge getting an even dispersal when it's coming into the manifold from the top.
Gerald - is the black gen I RT/10 really your old car? If so, that's a trip! I think the guy had a rear spoiler on the car, so if he's putting down those kind of hp numbers the nose must feel like it's on ice at speed.
Also, word was the owner quoted a 9.86 on street tires - I thought that sounded kinda generous given the utter lack of traction the setup must produce on street tires, even with a mid strip spray.
Gerald - is the black gen I RT/10 really your old car? If so, that's a trip! I think the guy had a rear spoiler on the car, so if he's putting down those kind of hp numbers the nose must feel like it's on ice at speed.
Also, word was the owner quoted a 9.86 on street tires - I thought that sounded kinda generous given the utter lack of traction the setup must produce on street tires, even with a mid strip spray.
Gerald
Enthusiast
Kid, yes, absolutely my old car. I installed the wing (Carbon fiber from Doug Levin, fully adjustable)... It also have automatic Lumbars, Fuel Cell for race gas, etc.The guy really knows how to drive very well and visits the track quite often, a racer his whole life. He called me estatic one day when he wiped a 1200cc rice bike off the road from a roll. That is the car that I told ppl about on the covette forum that I killed a GSX-750 EASY and they jumped all down my throat.. Believe me now??
I could never drive the car to its' full potential as I'm not a racer, but it was nice to have the power.... The car is absolutely friggin SICK!!! SICK!!!! I can only imagine a time like that would be street slicks, perhaps he meant those...?
Again, Kid, that car is pretty wicked huh? I had it for about a year and upgraded to a GenII GTS that is going to Dougs with the month for a similar setup.
Gerald
I could never drive the car to its' full potential as I'm not a racer, but it was nice to have the power.... The car is absolutely friggin SICK!!! SICK!!!! I can only imagine a time like that would be street slicks, perhaps he meant those...?
Again, Kid, that car is pretty wicked huh? I had it for about a year and upgraded to a GenII GTS that is going to Dougs with the month for a similar setup.
Gerald
Kid97GTS
Enthusiast
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Gerald:
Again, Kid, that car is pretty wicked huh? I had it for about a year and upgraded to a GenII GTS that is going to Dougs with the month for a similar setup.
Gerald
<HR></BLOCKQUOTE>
Gerald - yeah, that must be the same car - fuel cell and all! You know it's a wicked car when a load of older Viper guys are taking one look at the blower and spray and saying "Gee, how much power do you need......" - uh, guys, the C5 dealer is down the street to your left. Anyway, I can only imagine the mess that the Gen II will leave on the street when Doug is done with it - stop selling your old cars to West Coast guys - I don't need that type of peer pressure!
Again, Kid, that car is pretty wicked huh? I had it for about a year and upgraded to a GenII GTS that is going to Dougs with the month for a similar setup.
Gerald
<HR></BLOCKQUOTE>
Gerald - yeah, that must be the same car - fuel cell and all! You know it's a wicked car when a load of older Viper guys are taking one look at the blower and spray and saying "Gee, how much power do you need......" - uh, guys, the C5 dealer is down the street to your left. Anyway, I can only imagine the mess that the Gen II will leave on the street when Doug is done with it - stop selling your old cars to West Coast guys - I don't need that type of peer pressure!
Gerald
Enthusiast
Yeah, totally agree about the C5 comment, heh.
Let me guess,Did Larry leave the Carbon Fiber Dash kit in?, MGW goodies and CD changer in the trunk? hehe. Did he put that wicked paint job on it yet? ( He was talking about adding some flames to match his Bike)
Gerald
Let me guess,Did Larry leave the Carbon Fiber Dash kit in?, MGW goodies and CD changer in the trunk? hehe. Did he put that wicked paint job on it yet? ( He was talking about adding some flames to match his Bike)
Gerald
Kid97GTS
Enthusiast
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Gerald:
Yeah, totally agree about the C5 comment, heh.
Let me guess,Did Larry leave the Carbon Fiber Dash kit in?, MGW goodies and CD changer in the trunk? hehe. Did he put that wicked paint job on it yet? ( He was talking about adding some flames to match his Bike)
Gerald
<HR></BLOCKQUOTE>
Yep, loads of carbon fiber - as far as the trunk goes, after seeing that industrial sized bottle of juice and the fuel cell, my eyes were bugging out too far to much else. Paint still looks like the original, but he was wearing his Harley gear! Did you ever have a problem at high speed with the rear spoiler but not front splitter?
Yeah, totally agree about the C5 comment, heh.
Let me guess,Did Larry leave the Carbon Fiber Dash kit in?, MGW goodies and CD changer in the trunk? hehe. Did he put that wicked paint job on it yet? ( He was talking about adding some flames to match his Bike)
Gerald
<HR></BLOCKQUOTE>
Yep, loads of carbon fiber - as far as the trunk goes, after seeing that industrial sized bottle of juice and the fuel cell, my eyes were bugging out too far to much else. Paint still looks like the original, but he was wearing his Harley gear! Did you ever have a problem at high speed with the rear spoiler but not front splitter?
Gerald
Enthusiast
No I didn't at high speed it was extremely stable.. But I ALWAYS had the autoform hardtop on. When I installed that wing it was night and day difference without it. With it, 130 plus was a breeze (but hardtop was on). Yeah, he loves harleys....
Matt
Enthusiast
I'd really be interested to hear a technical answer to this question from a tuner such as Doug or Jason. I really don't think it's as straight forward as some here are saying. It seems a denser air charge WOULD enter the first cylinders. It also seems that the air/fuel ratio would vary from front to back because of this.
I've heard similar things to what Kid97GTS heard and it was not from someone with supercharger envy, it was from a Viper tech whos seen broken motors.
Anyone know why tuners such as McClure which used to advertise supercharger kits in Viper quarterly died?
Matt
I've heard similar things to what Kid97GTS heard and it was not from someone with supercharger envy, it was from a Viper tech whos seen broken motors.
Anyone know why tuners such as McClure which used to advertise supercharger kits in Viper quarterly died?
Matt
Ulysses
Enthusiast
Kid,
Was that the black RT at Deer Park with the wing? As soon as I heard that supercharger, I had to see what was under the hood. Then he opens the trunk and there's this HUGE bottle of nitrous! Very impressive.
Was that the black RT at Deer Park with the wing? As soon as I heard that supercharger, I had to see what was under the hood. Then he opens the trunk and there's this HUGE bottle of nitrous! Very impressive.
Gerald,
I wondered if that was your old car at the So Cal event at Deer Park. It caught the attention of everyone as it pulled in the lot from the S/C sound alone.
Using the Washer Bottle as a water injection tank was interesting. Have never seen a rear wing quite like it either.
The only thing there that got as much attention was the CDI engine with the 10 throttle body intake complete with A/C .. ready to put in a street Viper.
I wondered if that was your old car at the So Cal event at Deer Park. It caught the attention of everyone as it pulled in the lot from the S/C sound alone.
Using the Washer Bottle as a water injection tank was interesting. Have never seen a rear wing quite like it either.
The only thing there that got as much attention was the CDI engine with the 10 throttle body intake complete with A/C .. ready to put in a street Viper.
Gerald
Enthusiast
Yeah Marv, when I had the car I actually didn't like the whistling sound because NOONE EVER wanted to street race. Never had ONE soul wanting to race. I replaced the belt once and the whole day it was off I must have had a 1/2 dozen ppl wanting to race!! My next one will have NO whistle...
Doug Supercharged Vipers
Enthusiast
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Kid97GTS:
I had a chance to check out a Gen I Viper at a club meet this weekend - the car had a supercharger from a well-known builder, as well as nitrous. One of the guys there made a comment that got me wondering - he said "That supercharger setup will only charge the first 2 cylinders. There's no way the supercharger will get flow to all 10 the way it is set up." I didn't know enough about superchargers to really tell if this guy had a good point or was just benchbuilding.
<HR></BLOCKQUOTE>
Kid,
Good question...
It would make no difference where the intake manifold is pressurized (front, side, top, back) utilizing a centrifugal supercharger. Boost (or pressure) is only obtained at levels above atmosphere. It would be impossible to pressurize two cylinders and not others on an open plenum intake. The answer is simple, pressure is pressure, no matter where the compressor is located.
The car you saw was in fact Gerald's old car. It's our soon-to-be older design gen I supercharger system. Gen I cars will have a new makeover, they will share the same design as the Gen II S/C system.
Regards,
Doug
I had a chance to check out a Gen I Viper at a club meet this weekend - the car had a supercharger from a well-known builder, as well as nitrous. One of the guys there made a comment that got me wondering - he said "That supercharger setup will only charge the first 2 cylinders. There's no way the supercharger will get flow to all 10 the way it is set up." I didn't know enough about superchargers to really tell if this guy had a good point or was just benchbuilding.
<HR></BLOCKQUOTE>
Kid,
Good question...
It would make no difference where the intake manifold is pressurized (front, side, top, back) utilizing a centrifugal supercharger. Boost (or pressure) is only obtained at levels above atmosphere. It would be impossible to pressurize two cylinders and not others on an open plenum intake. The answer is simple, pressure is pressure, no matter where the compressor is located.
The car you saw was in fact Gerald's old car. It's our soon-to-be older design gen I supercharger system. Gen I cars will have a new makeover, they will share the same design as the Gen II S/C system.
Regards,
Doug
Went to the So Cal event on Sat and as we're driving back to Phoenix I thought "wonder if that was Gerald's S/C?" I pulled some photos off our camcorder so quality is not the best, still waiting for the 35mm to come back. For a "soon to be older system" it was MIGHTY impressive:
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<FONT size="-2">No, this is not my car, but I am a Viper owner, VCA member and figured some of you would like to see this machine.</FONT s>
You must be registered for see images
You must be registered for see images
More Photos of the car Click Here and then click on the photo you want to view .
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<FONT size="-2">No, this is not my car, but I am a Viper owner, VCA member and figured some of you would like to see this machine.</FONT s>
Doug Supercharged Vipers
Enthusiast
Marv,
You are talented! Those are great pics. I can tell you right now Gerald is suffering from withdrawals
Thanks for the mighty compliment,
Doug
You are talented! Those are great pics. I can tell you right now Gerald is suffering from withdrawals
You must be registered for see images
.... You just broke his heart.Thanks for the mighty compliment,
Doug
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Doug Supercharged Vipers:
I can tell you right now Gerald is suffering from withdrawals
<HR></BLOCKQUOTE>
I have a hunch he'll find a cure:
<FONT size="-2">Hey, that looks like a Gen 2 motor.....</FONT s>
<FONT COLOR="#ff0000" SIZE="1" FACE="Verdana, Arial">This message has been edited by Marv S on June 05, 2001 at 12:07</font>
I can tell you right now Gerald is suffering from withdrawals
You must be registered for see images
Doug<HR></BLOCKQUOTE>
I have a hunch he'll find a cure:
You must be registered for see images
<FONT size="-2">Hey, that looks like a Gen 2 motor.....</FONT s>
<FONT COLOR="#ff0000" SIZE="1" FACE="Verdana, Arial">This message has been edited by Marv S on June 05, 2001 at 12:07</font>
Kid97GTS
Enthusiast
I had a chance to check out a Gen I Viper at a club meet this weekend - the car had a supercharger from a well-known builder, as well as nitrous. One of the guys there made a comment that got me wondering - he said "That supercharger setup will only charge the first 2 cylinders. There's no way the supercharger will get flow to all 10 the way it is set up." I didn't know enough about superchargers to really tell if this guy had a good point or was just benchbuilding.
Anyway, can anyone shed some light on how the better known superchargers that are mounted up front near the throttle bodies can effectively reach all 10 cylinders? Thanks.
Anyway, can anyone shed some light on how the better known superchargers that are mounted up front near the throttle bodies can effectively reach all 10 cylinders? Thanks.
Gerald
Enthusiast
Dear Kid,
That is FUNNY!! That was my old car. That car is a beast..
Doug Levin built it . That guy you were talking to was just J-E-A-L-O-U-S..
"That supercharger setup will only charge the first 2 cylinders. There's no way the supercharger will get flow to all 10 the way it is set up."
LOL!!!! So that car has an extra 400 to 550HP (dont' know what kind of shot he put on it, but it was around 700HP before and it is a 200HP shot that would be about 900HP) on just 2 cylinders? hehehe That's a good one.. Tell the guy to show you what kind of narcotics he was taking when he made that statement.
Gerald
That is FUNNY!! That was my old car. That car is a beast..
Doug Levin built it . That guy you were talking to was just J-E-A-L-O-U-S..
"That supercharger setup will only charge the first 2 cylinders. There's no way the supercharger will get flow to all 10 the way it is set up."
LOL!!!! So that car has an extra 400 to 550HP (dont' know what kind of shot he put on it, but it was around 700HP before and it is a 200HP shot that would be about 900HP) on just 2 cylinders? hehehe That's a good one.. Tell the guy to show you what kind of narcotics he was taking when he made that statement.
Gerald
Kid97GTS
Enthusiast
Doug - thanks for the explanation. If that was the "old" setup, I'd love to see the new one!
Ulysses - Yep, that was the Levin Viper
Marv - Too bad I didn't know you'd be there, I could have finally put the face with the name!
Ulysses - Yep, that was the Levin Viper
Marv - Too bad I didn't know you'd be there, I could have finally put the face with the name!
Gerald
Enthusiast
FOR THE LOVE OF GOD, STOP!!!!
aaaaaaaaaaaaaaarrrrrrggggggggggggghhhhhhhhhhhhhhhhhhhhhhhh!!!!!!
I see he still has that pressure release radiator cap on it so he can fill the radiator easily!
Gerald
aaaaaaaaaaaaaaarrrrrrggggggggggggghhhhhhhhhhhhhhhhhhhhhhhh!!!!!!
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I see he still has that pressure release radiator cap on it so he can fill the radiator easily!
You must be registered for see images
Gerald
Doug Supercharged Vipers
Enthusiast
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Jeff Ellison (Austin, TX):
Doug, PLEASE MOVE TO TEXAS! What beautiful work! I'm guessing this would really mess me up on a Road Course,....but street or Drag racing, this would be a HOOT! How many hours have you guys got on S/C V-10's? I remember on our old board all the neigh say'ers comments that S/C'ed V-10's won't last...I guess the proof is in the life of these engines! (Come on Stock market, give me back my mad money!)
<HR></BLOCKQUOTE>Jeff, I fell blessed to have one of the best jobs in the world. The positive support from my customers allows me to continue one of the best projects I have ever ventured into. I've constructed many big HP marine motors for many, many years. The marine industry poses high demands on engines that must run like buses on and on in higher rpm bands.
The first time I removed a set of Viper heads from my own S/C motor, I inspected the cylinders and bearings and was absolutely delighted from what I found. Upon inspection, there was NO sign of any fatigue associated with a previous nitrous engines I had built in the past. The Viper V/10 is a short roded motor, therefore the pistons side-load the cylinders and scoring is inevitable, it just happens. Also, the stock Viper bearings are covered with a babbet material -- Not ideal for nitrous or race engines. When the pistons get shoved down hard, you can note the babbet wearing off the bearings, typically on the upper rod bearing, not the lower cap brg.
I've yet to find any of this type of engine wear on a properly tuned centrifugal forced inducted Viper motor. Boost is gradual and power is more linear, not like a jack hammer. Don't get me wrong, nitrous in *small doses* can be used successfully without the detriments.
As far as hours spent on development, call me at the shop this Sunday and I'll let you know
Thanks to all of you for the kind words,
You guys are terrific!
Doug
Doug, PLEASE MOVE TO TEXAS! What beautiful work! I'm guessing this would really mess me up on a Road Course,....but street or Drag racing, this would be a HOOT! How many hours have you guys got on S/C V-10's? I remember on our old board all the neigh say'ers comments that S/C'ed V-10's won't last...I guess the proof is in the life of these engines! (Come on Stock market, give me back my mad money!)
<HR></BLOCKQUOTE>Jeff, I fell blessed to have one of the best jobs in the world. The positive support from my customers allows me to continue one of the best projects I have ever ventured into. I've constructed many big HP marine motors for many, many years. The marine industry poses high demands on engines that must run like buses on and on in higher rpm bands.
The first time I removed a set of Viper heads from my own S/C motor, I inspected the cylinders and bearings and was absolutely delighted from what I found. Upon inspection, there was NO sign of any fatigue associated with a previous nitrous engines I had built in the past. The Viper V/10 is a short roded motor, therefore the pistons side-load the cylinders and scoring is inevitable, it just happens. Also, the stock Viper bearings are covered with a babbet material -- Not ideal for nitrous or race engines. When the pistons get shoved down hard, you can note the babbet wearing off the bearings, typically on the upper rod bearing, not the lower cap brg.
I've yet to find any of this type of engine wear on a properly tuned centrifugal forced inducted Viper motor. Boost is gradual and power is more linear, not like a jack hammer. Don't get me wrong, nitrous in *small doses* can be used successfully without the detriments.
As far as hours spent on development, call me at the shop this Sunday and I'll let you know
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.Thanks to all of you for the kind words,
You guys are terrific!
Doug
Matt
Enthusiast
What does the air/fuel ratio look like when moving from the front cylinders to the back? It would seem like the front would receive a denser air charge causing either a lean condition at the front or a rich condition at the back. This has been a documented problem on other front throttle-bodied manifolds.
Also, Doug, can you share with us what was inmproved upon from previous Viper supercharger designs to make them reliable? I've been told by a Viper tech that many early blower motors nuked themselves, hence those advertisers in old Viper Quarterly issues are no longer around.
Thanks,
Matt
Also, Doug, can you share with us what was inmproved upon from previous Viper supercharger designs to make them reliable? I've been told by a Viper tech that many early blower motors nuked themselves, hence those advertisers in old Viper Quarterly issues are no longer around.
Thanks,
Matt
Gerald
Enthusiast
Matt,
I'll admit I know nothing about engines, but why would the front cylinders receive a more dense charge WITH a S/C setup or WITHOUT? If we would use that theory then a non S/C setup would have a denser charge at the front cyclinders, no? only difference as Doug stated is that it's pressurized MORE. So it would seem if we would think about that, the dual throttle bodied viper EVEN WITHOUT a S/C would treat the front 2 cyclinders the same as the back 2 cylinders? I think I've really confused myself. I'll stick to what I do best... Buy/Sell..
Just my $1
I'll admit I know nothing about engines, but why would the front cylinders receive a more dense charge WITH a S/C setup or WITHOUT? If we would use that theory then a non S/C setup would have a denser charge at the front cyclinders, no? only difference as Doug stated is that it's pressurized MORE. So it would seem if we would think about that, the dual throttle bodied viper EVEN WITHOUT a S/C would treat the front 2 cyclinders the same as the back 2 cylinders? I think I've really confused myself. I'll stick to what I do best... Buy/Sell..
Just my $1
kverges
Enthusiast
I'll jump in with some limited knowledge. By way of background, I have personally supercharged with the Vortech "kits" available for the Mustang 5.0 and presently have a pretty heavily-modified (but daily-driven)'95 C4 based upon the Vortech Corvette Kit. I experimented with a S/C on the '93 RT/10 with a local "tuner," which was fabulously unsuccessful, but that's another story.
Doug did the setup and I have seen his work - marvelous craftsmanship and happy customers, so I know he does a fine job. The pics are the most detailed I have seen to date and reveal the answer to one of two important questions.
The questions are: (1) how do you supply extra fuel to go with the increased manifold pressure?; and (2) how do you control (usually retard) timing to avoid detonation? These questions are actually related, as increased timing can in effect lean out the mixture due to the combustion process starting sooner and therefore more completely burning the available fuel.
The pics (correct me if I am wrong, Doug) appear to reveal that Doug's solution was a "parallel" fuel system fed by an auxiliary fuel cell in the trunk. This is necessary because the stock fuel system has no fuel return line and "dead ends" at the manifold, making the rising rate fuel pressure regulator solution commonly used impossible. This auxiliary fuel tank feeds the extra injectors that you see on the tubes feeding the throttle bodies. Basically, this whole system can run independent of the stock fuel system and provide supplemental fuel as a function of boost pressure and rpms. There are electronic devices on the market to accomplish just this task and Doug may also use a rising-rate fuel pressure regulator to increase fuel pressure with boost.
To actually answer some of the questions, there may be some issue about mixture distribution of the auxiliary fuel. Notice that the injectors fire in front of the throttle bodies (unlike the factory injectors that fire into each runner) and at right angles to the air flow. It is probably impossible to say if the resulting mixture is evenly dispersed to each of the 10 cylinders, but I doubt it is a big problem (otherwise the car would have blow up long ago!). I also suspect the setup is programmed to run fairly rich, which is conservative and safe. As I explain below, I would prefer to control the factory injectors in order to eliminate this concern and provide the extra fuel at the point the manifold was designed to have fuel introduced.
I still wonder about timing. Traditional boost retard products are no good with the Viper because it has no distributor. There are now supposedly "boost retard" products that will work with DIS (distibutorless) systems to retard timing as a function of boost. With low boost pressures and enough fuel, timing retard might not be necessary at all.
This leads me to why I have never tackled the Viper S/C system. On my C4 and earlier cars, I could actually monitor and program the factory computer. I can change fuel injector sizes, pulsewidth and timing and then monitor the results via the factory O2 sensors (and knock sensor, which the Viper does not have)and a wideband O2 on a chassis dyno. I am very comfortable that I can safely obtain about a 12:1 air:fuel ratio and can avoid detonation. I consider this a preferred solution and I can't do this on the Viper. You might just run the whole shebang with a MOTEC controller, but then you have likely spend $10K or so just on the computer. Then I wonder how you interact with the other stuff the computer manages, like evaporative emissions, speedometer, cooling fans, etc. I would vastly prefer to just re-program the Viper PCM, but alas, there is no way that I have access to.
Oh, the software exists to reflash late-model Viper PCMs for performance purposes, but it is closely controlled and done only on an exchange basis. I am not 100% confident that timing and injector events can be precisely mapped over all rpm and load factors. Regardless, I just don't bellieve in mail-order programming with significant mods like forced induction. Maybe the tuners are able to do accurate long-distance programming, but I sure don't see how! I have to precisely monitor and fine-tune the programming on my C4 based upon several dyno pulls. In addition, I find that I have to make seasonal changes to my programming on my C4. I think it is a factor of fuel formulations and perhaps ambient temps.
Finally, on the early Vipers, the PCMs cannot be "flash programmed," but have dedicated chips. Usually not a problem on other cars, but I think the Viper PCM is epoxy-potted, so there is no easy way to remove and replace the "chip." Ever notice how there are no "chips" for Vipers? So I think there is probably no choice but to piggyback on the stock computer to provide extra fuel and control timing on the '92-95 Viper.
Well, my geek alert is going off big time. I'd sure love it if a kit was available, but it probably makes no sense. First, you don't want to make the technology available and second, there are parts of the install that are beyond most DIY folks (like adding a keyway to the crank in order to not spin the balancer on the crank snout). I sure do wish I could get a kit, though, as the prospect of customer service 1000+ miles away is just too much.
Anyone want to jump in and "get technical" and fill in the gaps/correct my errors?
Doug did the setup and I have seen his work - marvelous craftsmanship and happy customers, so I know he does a fine job. The pics are the most detailed I have seen to date and reveal the answer to one of two important questions.
The questions are: (1) how do you supply extra fuel to go with the increased manifold pressure?; and (2) how do you control (usually retard) timing to avoid detonation? These questions are actually related, as increased timing can in effect lean out the mixture due to the combustion process starting sooner and therefore more completely burning the available fuel.
The pics (correct me if I am wrong, Doug) appear to reveal that Doug's solution was a "parallel" fuel system fed by an auxiliary fuel cell in the trunk. This is necessary because the stock fuel system has no fuel return line and "dead ends" at the manifold, making the rising rate fuel pressure regulator solution commonly used impossible. This auxiliary fuel tank feeds the extra injectors that you see on the tubes feeding the throttle bodies. Basically, this whole system can run independent of the stock fuel system and provide supplemental fuel as a function of boost pressure and rpms. There are electronic devices on the market to accomplish just this task and Doug may also use a rising-rate fuel pressure regulator to increase fuel pressure with boost.
To actually answer some of the questions, there may be some issue about mixture distribution of the auxiliary fuel. Notice that the injectors fire in front of the throttle bodies (unlike the factory injectors that fire into each runner) and at right angles to the air flow. It is probably impossible to say if the resulting mixture is evenly dispersed to each of the 10 cylinders, but I doubt it is a big problem (otherwise the car would have blow up long ago!). I also suspect the setup is programmed to run fairly rich, which is conservative and safe. As I explain below, I would prefer to control the factory injectors in order to eliminate this concern and provide the extra fuel at the point the manifold was designed to have fuel introduced.
I still wonder about timing. Traditional boost retard products are no good with the Viper because it has no distributor. There are now supposedly "boost retard" products that will work with DIS (distibutorless) systems to retard timing as a function of boost. With low boost pressures and enough fuel, timing retard might not be necessary at all.
This leads me to why I have never tackled the Viper S/C system. On my C4 and earlier cars, I could actually monitor and program the factory computer. I can change fuel injector sizes, pulsewidth and timing and then monitor the results via the factory O2 sensors (and knock sensor, which the Viper does not have)and a wideband O2 on a chassis dyno. I am very comfortable that I can safely obtain about a 12:1 air:fuel ratio and can avoid detonation. I consider this a preferred solution and I can't do this on the Viper. You might just run the whole shebang with a MOTEC controller, but then you have likely spend $10K or so just on the computer. Then I wonder how you interact with the other stuff the computer manages, like evaporative emissions, speedometer, cooling fans, etc. I would vastly prefer to just re-program the Viper PCM, but alas, there is no way that I have access to.
Oh, the software exists to reflash late-model Viper PCMs for performance purposes, but it is closely controlled and done only on an exchange basis. I am not 100% confident that timing and injector events can be precisely mapped over all rpm and load factors. Regardless, I just don't bellieve in mail-order programming with significant mods like forced induction. Maybe the tuners are able to do accurate long-distance programming, but I sure don't see how! I have to precisely monitor and fine-tune the programming on my C4 based upon several dyno pulls. In addition, I find that I have to make seasonal changes to my programming on my C4. I think it is a factor of fuel formulations and perhaps ambient temps.
Finally, on the early Vipers, the PCMs cannot be "flash programmed," but have dedicated chips. Usually not a problem on other cars, but I think the Viper PCM is epoxy-potted, so there is no easy way to remove and replace the "chip." Ever notice how there are no "chips" for Vipers? So I think there is probably no choice but to piggyback on the stock computer to provide extra fuel and control timing on the '92-95 Viper.
Well, my geek alert is going off big time. I'd sure love it if a kit was available, but it probably makes no sense. First, you don't want to make the technology available and second, there are parts of the install that are beyond most DIY folks (like adding a keyway to the crank in order to not spin the balancer on the crank snout). I sure do wish I could get a kit, though, as the prospect of customer service 1000+ miles away is just too much.
Anyone want to jump in and "get technical" and fill in the gaps/correct my errors?
Doug Supercharged Vipers
Enthusiast
Keith, Matt -
As you know, the Viper does run a "one pipe" fuel system as do all new cars now to eliminate fuel vapors and comply to Government mandated emission standards. Our S/C system replaces the one pipe with a return type (two way) fuel system. We don't rely on our IAC (additional injector controller) to supply -all- the needed fuel for supercharging. Superchargers as well as turbo's require a minimum of 1lb of increase in fuel pressure per pound of boost. The factory one pipe system cannot increase fuel pressure in it's present form. Our IAC by itself, will NOT suffice for all the rq'd extra fuel. Also, as I stated earlier regarding increasing fuel pressure, the factory injectors would be forced shut without the increased fuel pressure -- This would most certainly cause a lean-out condition.
Matt, To answer your question regarding AF ratio per cylinder, we measure AF in total (not per cylinder) via a lambda wide band 02. It provides us with real time data. During initial testing, we tested our systems with EGT probes in EACH cylinder to obtain a safe EGT level for EVERY cylinder. We also have a program that plugs into our computer that interfaces with the factory PCM. We can map and change parameters on our computer that provides us with data acquisition in real time. Reading spark plugs (every one) along with other proper tuning aids is important too. You can have all the proper AFR and EGT readings and still detonate an engine. Of course other factors still apply. Timing is under control and can be adjusted in the cockpit on every one of our cars.
Keith, This is my take on "chips" for ECU's. A chip is only a fixed input. On any given day temperatures and conditions change, that's why we prefer to interphase with PCM inputs.
Hope this helps,
Doug
As you know, the Viper does run a "one pipe" fuel system as do all new cars now to eliminate fuel vapors and comply to Government mandated emission standards. Our S/C system replaces the one pipe with a return type (two way) fuel system. We don't rely on our IAC (additional injector controller) to supply -all- the needed fuel for supercharging. Superchargers as well as turbo's require a minimum of 1lb of increase in fuel pressure per pound of boost. The factory one pipe system cannot increase fuel pressure in it's present form. Our IAC by itself, will NOT suffice for all the rq'd extra fuel. Also, as I stated earlier regarding increasing fuel pressure, the factory injectors would be forced shut without the increased fuel pressure -- This would most certainly cause a lean-out condition.
Matt, To answer your question regarding AF ratio per cylinder, we measure AF in total (not per cylinder) via a lambda wide band 02. It provides us with real time data. During initial testing, we tested our systems with EGT probes in EACH cylinder to obtain a safe EGT level for EVERY cylinder. We also have a program that plugs into our computer that interfaces with the factory PCM. We can map and change parameters on our computer that provides us with data acquisition in real time. Reading spark plugs (every one) along with other proper tuning aids is important too. You can have all the proper AFR and EGT readings and still detonate an engine. Of course other factors still apply. Timing is under control and can be adjusted in the cockpit on every one of our cars.
Keith, This is my take on "chips" for ECU's. A chip is only a fixed input. On any given day temperatures and conditions change, that's why we prefer to interphase with PCM inputs.
Hope this helps,
Doug
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Matt
Enthusiast
Gerald,
I uderstand what you are saying and I sort of have the same perception. I'm really asking because I haven't been given a technical answer one way or the other. The only justification I've received is that at non-forced induction levels this phenominon is not as detrimental (?). Also, a tech has seen nuked motors from something along these lines and I'd like to try and understand how and why Viper supercharging is working now, but has failed in the past.
Edit: I've spoken with someone regarding this issue and it appears I may have it backwards. He feels that in forced induction applications with front mounted throttle bodies the air charge can actually be blown past the front cylinder ports. (?)
Again, a technical response from some more knowledgable would be enlightening.
Matt
I uderstand what you are saying and I sort of have the same perception. I'm really asking because I haven't been given a technical answer one way or the other. The only justification I've received is that at non-forced induction levels this phenominon is not as detrimental (?). Also, a tech has seen nuked motors from something along these lines and I'd like to try and understand how and why Viper supercharging is working now, but has failed in the past.
Edit: I've spoken with someone regarding this issue and it appears I may have it backwards. He feels that in forced induction applications with front mounted throttle bodies the air charge can actually be blown past the front cylinder ports. (?)
Again, a technical response from some more knowledgable would be enlightening.
Matt
Doug Supercharged Vipers
Enthusiast
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Doug Supercharged Vipers:
IAC (additional injector controller).
<HR></BLOCKQUOTE>Oops, AIC (not IAC)..... 12:00 AM here and time for sleep!
Doug
IAC (additional injector controller).
<HR></BLOCKQUOTE>Oops, AIC (not IAC)..... 12:00 AM here and time for sleep!
Doug
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