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Supercharger Question for Lenny


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Lenny,

I am looking for power upgrades. I contacted Silverbullet and they said they are a couple of weeks out from putting a supercharger together (which really means a couple of months). I also assume they are building a system based on a lot of input from you.

There are some pretty inexpensive turbo systems out there, but I want instant throttle response if possible.I don't feel a centrifugal blower has much advantage over a turbo, so a roots type blower is what I am looking at just as you have, but I have a few questions.

Do you think your supercharger would work well with an FMU instead of purchasing a whole new programable computer and larger injectors? From what I have read an FMU is an easy alternative to a computer reprogram. I understand the way your system is set up is the best, but you were having tuning issues.

Would you do anything differently if you were to do it a second time?

Thanks

Paul

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Lenny,

I am looking for power upgrades. I contacted Silverbullet and they said they are a couple of weeks out from putting a supercharger together (which really means a couple of months). I also assume they are building a system based on a lot of input from you.

There are some pretty inexpensive turbo systems out there, but I want instant throttle response if possible.I don't feel a centrifugal blower has much advantage over a turbo, so a roots type blower is what I am looking at just as you have, but I have a few questions.

Do you think your supercharger would work well with an FMU instead of purchasing a whole new programable computer and larger injectors? From what I have read an FMU is an easy alternative to a computer reprogram. I understand the way your system is set up is the best, but you were having tuning issues.

Would you do anything differently if you were to do it a second time?

Thanks

Paul

Initially I had some tuning issues but that went away when I got the right injectors in and resolved a fuel pressure problem. It took two trys to get the injectors right with the second set working fine. The first set were 22# injectors and they worked quite well but I felt it wanted a bit more so I went with 26# injectors. Haven't done my final Dyno work yet but will soon now, hopefully in 2-3 weeks. Went out this past weekend and was doing trails at 12-15 hundred RPMs in 4th and 5th gear. I'm careful not to lug it in the low RPMs but didn't have to shift much. Pulled all but the steeper hills in 3rd gear, again at relatively low RPMs. Found that if I get it to about 1800 RPMs, 3rd would continously pull long hills. Only in the knarly stuff did I need to go to 2nd or 1st. That was usually because the terain was such that I needed to go slow and that slow in 3rd brought the RPMs down to 1000 or 1200 and without any forward momentum, 3rd would try to pull it and does to a point but lugs and can't gain speed thus it keeps lugging. There is no way I would ever go back to a stock power setup. Driveability is in a completely different world and real nice. Much better then when Rocmoc last drove it and it will get better yet. You can do a casual chug down the trails without shifting all the time very easily and when you want to hot rod it, it's a riot, again because you can pull out of corners strong without dropping down into the lower gears. I finding mine is actually getting stronger which I suspect is the result of the rings finally seating from when I lowered the compression. Thats only about 1000 miles ago so that would make sense. Actually I could have gotten a bit more power if I didn't drop my compression quite as much. I now know it could have taken a little more compression and be fine.

As far as SilverBullets supercharger goes, it should be nearly a clone of what I have. I'm in my 4th variation of how I arranged and setup this supercharger and now i'm satisfied it's right. Yes, I did work closely with him and provided him with blueprints to go buy along with explaining everything I did and why. I suspect he will make some changes but only for production reasons. When I get my final tune on the dyno, I will be providing him with the complete tuning tables I use. That way if everything is done that I did, it should be pretty much plug and play. I'm not a turbo guy but I would think that when chugging along at low RPMs, the turbo will struggle to provide much boost where my supercharger provides twice the normal asperation air per revolution no matter what RPM it is at. You will need to provide a muffled input to tame the supercharger noise coming back through the intake, but that is easy. I do feel confident that SilverBullet will bend over backwards to make sure the first few supercharger installations go right. He did this with Plumber when he had a problem installing the torque cams from him. The cam problem Plumber had wasn't Silversbullets fault but the mechanic Plumber trusted let him down and caused some serious problems. SilverBullet is working close with him to get things back right. I can't tell you about the FMU. It might work fine but I also have spark timing changes that help. I've been told that the real horsepower is found with the spark timing. Of course the air fuel ratio has to be close to optium too. Just good air fuel ratios helps a lot but is inproved a lot with proper timing. I am not running a loop back system where the computer reads the oxygen fuel sensor and adjust to conditions. Agian I was told by my dyno guy that this is fine for max ECO reasons but not for top preformance.

I see Randy is getting 25 mpg with his turbo where as I'm getting about 12 (driving sort of fast) but I am running 93 octain pump gas so that part then seems to even out. When I was at Unleashed and spoke with Scott, he was using 2 fuel pumps and pushing the fuel pressure up to about 140 psi.

Lenny

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Initially I had some tuning issues but that went away when I got the right injectors in and resolved a fuel pressure problem. It took two trys to get the injectors right with the second set working fine. The first set were 22# injectors and they worked quite well but I felt it wanted a bit more so I went with 26# injectors. Haven't done my final Dyno work yet but will soon now, hopefully in 2-3 weeks. Went out this past weekend and was doing trails at 12-15 hundred RPMs in 4th and 5th gear. I'm careful not to lug it in the low RPMs but didn't have to shift much. Pulled all but the steeper hills in 3rd gear, again at relatively low RPMs. Found that if I get it to about 1800 RPMs, 3rd would continously pull long hills. Only in the knarly stuff did I need to go to 2nd or 1st. That was usually because the terain was such that I needed to go slow and that slow in 3rd brought the RPMs down to 1000 or 1200 and without any forward momentum, 3rd would try to pull it and does to a point but lugs and can't gain speed thus it keeps lugging. There is no way I would ever go back to a stock power setup. Driveability is in a completely different world and real nice. Much better then when Rocmoc last drove it and it will get better yet. You can do a casual chug down the trails without shifting all the time very easily and when you want to hot rod it, it's a riot, again because you can pull out of corners strong without dropping down into the lower gears. I finding mine is actually getting stronger which I suspect is the result of the rings finally seating from when I lowered the compression. Thats only about 1000 miles ago so that would make sense. Actually I could have gotten a bit more power if I didn't drop my compression quite as much. I now know it could have taken a little more compression and be fine.

As far as SilverBullets supercharger goes, it should be nearly a clone of what I have. I'm in my 4th variation of how I arranged and setup this supercharger and now i'm satisfied it's right. Yes, I did work closely with him and provided him with blueprints to go buy along with explaining everything I did and why. I suspect he will make some changes but only for production reasons. When I get my final tune on the dyno, I will be providing him with the complete tuning tables I use. That way if everything is done that I did, it should be pretty much plug and play. I'm not a turbo guy but I would think that when chugging along at low RPMs, the turbo will struggle to provide much boost where my supercharger provides twice the normal asperation air per revolution no matter what RPM it is at. You will need to provide a muffled input to tame the supercharger noise coming back through the intake, but that is easy. I do feel confident that SilverBullet will bend over backwards to make sure the first few supercharger installations go right. He did this with Plumber when he had a problem installing the torque cams from him. The cam problem Plumber had wasn't Silversbullets fault but the mechanic Plumber trusted let him down and caused some serious problems. SilverBullet is working close with him to get things back right. I can't tell you about the FMU. It might work fine but I also have spark timing changes that help. I've been told that the real horsepower is found with the spark timing. Of course the air fuel ratio has to be close to optium too. Just good air fuel ratios helps a lot but is inproved a lot with proper timing. I am not running a loop back system where the computer reads the oxygen fuel sensor and adjust to conditions. Agian I was told by my dyno guy that this is fine for max ECO reasons but not for top preformance.

I see Randy is getting 25 mpg with his turbo where as I'm getting about 12 (driving sort of fast) but I am running 93 octain pump gas so that part then seems to even out. When I was at Unleashed and spoke with Scott, he was using 2 fuel pumps and pushing the fuel pressure up to about 140 psi.

Lenny

Yeah, your supercharger just sounds awesome. I really like the one you selected too (Aisin). The only downside is it is a little noisey, but that is inherant of a roots type blower. If it was dollar for dollar the same price as a turbo I would go with the supercharger, but it sounds like it will require a programable computer, injectors, & an new fuel pump which will up the price over a turbo. And, I believe a intercooler should be run with a roots blower which will up the price even more.

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Yeah, your supercharger just sounds awesome. I really like the one you selected too (Aisin). The only downside is it is a little noisey, but that is inherant of a roots type blower. If it was dollar for dollar the same price as a turbo I would go with the supercharger, but it sounds like it will require a programable computer, injectors, & an new fuel pump which will up the price over a turbo. And, I believe a intercooler should be run with a roots blower which will up the price even more.

I do use an intercooler. I kind of always figure that if I can't get what I really want, I just wait until I can. Being retired, I don't want to spend the best part of my life living with something other then what I really want. Then again, it can get expensive but I can't take it with me. Yes I run the Aisin 500cc compressor, spinning it 2:1 with the engine, and the aftercooler made quite a differance. Didn't have it at first and had more boost but more boost at higher temp limits how hard you can push the engine. That is how I ended up with lower compression then I could have now. Was getting pre-ignition. I dropped 2 or 3 psi with the intercooler and now my compression could raise maybe from my current about 7:1 to 8:1. At full boost that would give me about 11-3/4:1 where as now I'm about 11:1. I don't want to go higher then 11-3/4:1 so I can run pump gas. If I ever tear it down again, I will go to different pistons to raise the compression. I find that I work the engine far less then when stock where I was always reving it to get it to go. Hitting the rev limiter frequently. Now I never hit it and have even set the rev limit down to 5700 RPMs just to be conservative with the engine. Don't need to rev that high anymore. I figure that my engine will run much longer with the supercharger because now I don't have to scream it all the time.

The cost for the programable computer, injectors and intercooler wouldn't be more then about $1500. I only run 55 pounds of fuel pressure so the stock pump would do the job all though a low pressure fuel pump into an accumulator before the main pump set up will steady the flow and eliminate air. That is what I have.

Lenny

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  • 3 weeks later...

Another question for you since you are our boost guru. I am trying to decide where I might place my aftercooler. Are there drawbacks from having longer tube coming from the supercharger to the intake than a shorter one. I figure a longer tube would help the air cool more, but would there be significant pressure loss or power delay from being longer when you could have it shorter? Since it will need more air to build the same amount of pressure as a shorter tube? Or, do you think it would even be noticeable?

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Another question for you since you are our boost guru. I am trying to decide where I might place my aftercooler. Are there drawbacks from having longer tube coming from the supercharger to the intake than a shorter one. I figure a longer tube would help the air cool more, but would there be significant pressure loss or power delay from being longer when you could have it shorter? Since it will need more air to build the same amount of pressure as a shorter tube? Or, do you think it would even be noticeable?

There are some advantages to boths long or short. On a top fuel dragster, the supercharger is after the throttle body. They want absolute instant response. I run a longer intake setup, primarily to get everything in. My throttle body is after the supercharger. The supercharger is to the rear of the engine above the water pump. The outlet runs from there to the left side of the engine to the aftercooler, about 10". The aftercooler runs along the side of the engine sort of next to the shock. It's probably about 15" long, I have a good sized aftercooler, about 12x12. The aftercooler outlet is low, sort of down just above the stock location of the battery. From there a U shaped tube, about 15" long brings it up to the top where it connects to the throttle body. My intake manifold has been flipped so the aluminum plentum is on top. The supercharger pumps more air then the engine sucks thus a pressure build. This volumn before the throttle body fills quickly and maintains a certain amount of built up pressure anyway. There is a waste gate valve in this section so when I let up on the throttle, any pressure build up is partially released. I really don't want this to have a full standing charge because if there was, when I opened the throtle quickly I would get a pressure pop into the intake which would then drop off some. This would make tuning in this situation hard to get right because of the fulctuating pressures. I rather like the pressure to have to build a bit so this smooths this out. When the engine is just running easy, the pressure will build some anyway in the aftercooler part of the tubing structure. When I hit the throttle, I show a very quick boost , basically at the same time I hit the throttle. I'm not showing this boost in the aftercooler part of things but in the intake plentum after the throttle body as this is where you want the boost sensor reading from. I don't have a gage in the other area. This boost is about 5-6 pounds. As the motor revs more, the boost increases to about 8-9 pounds. I'm going to change this to about 10-11 pounds. The boost increases with revs because as you run more air thru the intake system, the less efficient it gets thus the supercharger produces it faster then what the engine is capable of using. Remember that just because you have 10 pounds of boost doesn't mean that there is 10 pounds more pressure in the piston chamber. The power increase from the boost is quick and smooth and very driveable. I don't want a light switch setup like a dragster. You still need to be able to feather the power at lower RPMs like in rock crawling or going thru tight spots. A supecharger is different from a turbo charger in that it doesn't need to get reved up first. It's always turning, in my case, twice as fast as the engine so I'm building pressure even at idle..

Lenny

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There are some advantages to boths long or short. On a top fuel dragster, the supercharger is after the throttle body. They want absolute instant response. I run a longer intake setup, primarily to get everything in. My throttle body is after the supercharger. The supercharger is to the rear of the engine above the water pump. The outlet runs from there to the left side of the engine to the aftercooler, about 10". The aftercooler runs along the side of the engine sort of next to the shock. It's probably about 15" long, I have a good sized aftercooler, about 12x12. The aftercooler outlet is low, sort of down just above the stock location of the battery. From there a U shaped tube, about 15" long brings it up to the top where it connects to the throttle body. My intake manifold has been flipped so the aluminum plentum is on top. The supercharger pumps more air then the engine sucks thus a pressure build. This volumn before the throttle body fills quickly and maintains a certain amount of built up pressure anyway. There is a waste gate valve in this section so when I let up on the throttle, any pressure build up is partially released. I really don't want this to have a full standing charge because if there was, when I opened the throtle quickly I would get a pressure pop into the intake which would then drop off some. This would make tuning in this situation hard to get right because of the fulctuating pressures. I rather like the pressure to have to build a bit so this smooths this out. When the engine is just running easy, the pressure will build some anyway in the aftercooler part of the tubing structure. When I hit the throttle, I show a very quick boost , basically at the same time I hit the throttle. I'm not showing this boost in the aftercooler part of things but in the intake plentum after the throttle body as this is where you want the boost sensor reading from. I don't have a gage in the other area. This boost is about 5-6 pounds. As the motor revs more, the boost increases to about 8-9 pounds. I'm going to change this to about 10-11 pounds. The boost increases with revs because as you run more air thru the intake system, the less efficient it gets thus the supercharger produces it faster then what the engine is capable of using. Remember that just because you have 10 pounds of boost doesn't mean that there is 10 pounds more pressure in the piston chamber. The power increase from the boost is quick and smooth and very driveable. I don't want a light switch setup like a dragster. You still need to be able to feather the power at lower RPMs like in rock crawling or going thru tight spots. A supecharger is different from a turbo charger in that it doesn't need to get reved up first. It's always turning, in my case, twice as fast as the engine so I'm building pressure even at idle..

Lenny

So it sounds like your aftercooler is not in a path of direct airflow. Is that correct? Is there a way to mount the supercharger with out flipping the intake?

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So it sounds like your aftercooler is not in a path of direct airflow. Is that correct? Is there a way to mount the supercharger with out flipping the intake?

The aftercooler has a fan on it which blows from the outer side towards the engine. This is wired into the other fan solenoid so it runs when the other fan does. The manifold is easy to flip. It's almost a direct flip. Once flipped you can get at the throttle body along with the IAC and TPS which is all but impossible to get at in the stock position. Besides, you need to match the ports between the aluminum plentum and the tubes going to the head along with the tubes to head ports too. Also match the throttle body to the plentum. It will be far easier to flip the manifold then trying to work with it below. Plus, a down draft intake is always better then an up draft one. You can get some nice aftercooler tubing kits on Ebay that will provide lots of tubing and couplers. Just cut and weld to your needed configeration.

Lenny

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What did you find Lenny? If you don't mind sharing.

It's another brand of blower but it will require redevelopment of the system from the ground up. I was throwing it out to Rick in case he wanted to sometime in the future, play with the idea. I would be interested in working with him on it. It remains to be seen if this new blower would work without causing problems. For now, the supercharger I'm using which is also what Silverbullet is using is a good working setup.

Lenny

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