Forced induction Questions and Such for the Slingshot

    Quote from SaltyClownNY

    Hey, question I've been thinking about... need some help with some info from folks like @Slingrazor and @ericastar76 who I believe are running stock engine and superchargers. Whats the high end of "safe" limits on the stock engine for boost pressure? I know some are running the 95 pulley and getting around 340HP, but what is the boost level for that? By my calculations, it's about 15 - 16PSI on a stock engine, no? Who else is running the supercharger with 95 pulley?

    @SaltyClownNY SC or Turbo I wouldn’t push more than 10# on a stock engine. That’s pretty much the safe zone. If you want a little more assurance, throw in some ARP headbolts. Cheap insurance.

    Quote from SaltyClownNY

    Hey, question I've been thinking about... need some help with some info from folks like @Slingrazor and @ericastar76 who I believe are running stock engine and superchargers. Whats the high end of "safe" limits on the stock engine for boost pressure? I know some are running the 95 pulley and getting around 340HP, but what is the boost level for that? By my calculations, it's about 15 - 16PSI on a stock engine, no? Who else is running the supercharger with 95 pulley?

    Just a couple quick notes on why using boost pressure as the determining factor of what a block will take is not the only factor you should be looking at, especially when it comes to turbos. The turbine section of a turbo does act as a restriction in the exhaust of the engine, so a smaller turbine will generally cause more restriction to flow than a larger turbine. If you would compare 2 different turbos making the same power, but one with a larger turbine, in general the larger turbine turbo will make the same power at lower pressure. In general the 300hp/torque limit on the stock engine has seemed to be working well as a point at which, if over that power/torque you should be looking at building the engine for more power. So, the size of the turbo being used will determine what pressure is needed to make 300hp a the wheels and that pressure required will be different depending on which turbo is used.


    Also, in the case of changing cams on the supercharger kits, when the new cams are installed, the pressure actually decreases, but power increases. This is because we are changing the volumetric efficiency of the engine with the cams and the longer duration and slightly higher lift, so there is less restriction for the supercharger to push against, airflow increases and pressure decreases.

    Quote from Fla tom

    Is there any word on the cost of a new tune from bob for an old supercharger? Also what is the cost on a map clip? Generally mine runs quite well but cold starts take a bit of feathering the throttle.

    I did talk to Bob while I was traveling and the tune update will be $200, we are going to be flashing a couple of Slingshots in the coming week hopefully just to get some more feedback on the tune and then will start having the tune available through Bob.


    Hope that helps,
    Dave

    Thanks all!


    What I'm attempting to do is understand the limits of my turbo and a stock engine. Hahn provided a tune file that seems solid with the Street Race Intake manifold. We can argue about injector sizes and such and which system is better and they are all valid points, but doesn't change the fact that I have one and not replacing it right now until I feel like I've exhausted all my options to get what I can out of it.


    So that being said, the tune file for the FIC that was provided Bill had stated is getting about 250 HP at the wheel. So here are some facts I know of:

    • lots go into a 1/4 mile time. Surface conditions, tires, experience, etc.
    • My "experience" is novice, but I'm learning. Part of the reason for all this. Been messing with suspension and tires for a bit as well.
    • I have the machine to tweak and mess with. The above is basically staying at more or less a constant. So finding the best setup that gives me the fastest times is what I'm shooting for and then what can I do to improve that. Experience will come.

    So knowing the above...

    • With others running 340 HP or higher (although with supper chargers), I believe the 250HP is low for the Hahn system and what it can handle (on the VERY safe side). One option is to increasing HP. A better tune file and or putting the sling in the 2x is an option, but I have a stock engine. 2x will give me up to about 10PSI I believe.
    • I know the sling can be faster than 15.5 second quarter mile. So just trying to figure out what I can do with the setup I have. Examining boost pressure and HP is just one data point as Dave pointed out above, but finding the upper limit of what is "safe" seems to be what I'm attempting to do.
    • So figuring out what is the top PSI for the turbo we have with a stock engine is what I'm trying to figure out. How do you know what is too much... BEFORE you blow the engine LOL.

    :00000436:
    Success is a lousy teacher. It seduces smart people into thinking they can't lose. - Bill Gates

    1. Go ahead now and start shopping for a salvage yard engine to replace the one you have.


    2. If your lust for more power is strong go ahead and buy another one like you have (they are cheaper) to put in when you blow yours. That way you can still be riding while you build a better one.


    3. Go ahead now and start shopping for a LEA or LAF engine. Get with Dave and he will head you in the right direction on pistons, rods, cams ect. BTW you will need the top end off the engine that you have now or the one you buy to replace it when you blow it because the LEA and LAF are direct injection so you can't use their top end.


    4. Next you'll want to get with Dave and Bob to set up a time when you can bring the sling with the new "built" engine to the dyno to see how much total boost that you can get out of your current turbo charger.


    5. Now that you've maxed out the capabilities of your current turbo charger you will need to again get with Dave and Bob to select the new turbo charger and tune that you will be purchasing. After all you have a built motor that can withstand whatever you can put on it so why would you stick with an inferior under powered turbo when you can have more power.


    6. Next you will need to contact those who have installed alternate power trains in excess of 1000hp. Might also be a good time to check up on your life insurance and upgrade your pilots license to include "high performance".


    Enough is never enough!


    Tim "Ghost" Ganey
    Winfield, Alabama
    205spam412spam2868

    I do not know a whole lot about all of this, but I do know that you cannot compare the numbers from one dyno with another. You will probably not get the same numbers on each dyno.

    @FunCycle, Dave gave a post some time ago where the vendors are comparing each others systems. I agree that it's hard to do and in some ways, the vendors are putting their own system in the best light and working to discredit the other brands out there, so can be a bit misleading. My take away from Dave's comments was that there is a standards for measuring the system on the dyne and that they both have to be using the same standards. I would think it would be close.


    @Ghost LOL... Yes, there are a LOT of ways to do myself off. The key is that with my current setup, I'd like to get what I can out of it. The Hahn setup wasn't cheep all on it's own. If I'm at 250HP at the wheel now, is it possible to get to 275HP or even 300HP on the stock engine. I really have no desire to be at 1000HP, but I would like to get the most out of what I did purchase and at the moment, I don't feel as though that is the case. The system I know is capable of more, but when is it too much for the stock engine I don't know.

    :00000436:
    Success is a lousy teacher. It seduces smart people into thinking they can't lose. - Bill Gates

    hmmm, again, I posted somewhere about this, and Dave can probably chime in, but it's possible to run 300ish HP on the stock engine. In my case, Alpha Turbo, the only thing they recommended before increasing boost was the head bolts. 300ish hp has been been measured and tested on several dyno's with different vendor Turbos and/or SC and your engine's pretty safe running that. DDM's SC is running in that range as well while staying with the stock block. What you have to do with your setup to get there is anybody's guess. Now, if you want to go into real HP #'s, do what others are mentioning.... go out and get you a donor motor and build one up....then you can play with the big boys and their big HP #'s. I've been trying for 2 years to blow this motor up so I have an excuse to go there but she's still running strong (knock on wood) :thumbsup:

    I believe Bill stated the 250 HP was at 6# of boost, we should be I believe at the 2 level around 275 HP with 7.5# at least that is what I'm getting pressure wise.
    2x will move the pressure up to 8.5ish I believe.


    From what I've been lead to believe from my research it's not a 1/4 machine with 1 wheel in the back. @StickerDick I believe runs 1/2 mile drag strip. He's also running a 345 rear


    Quote from SaltyClownNY

    @FunCycle, Dave gave a post some time ago where the vendors are comparing each others systems. I agree that it's hard to do and in some ways, the vendors are putting their own system in the best light and working to discredit the other brands out there, so can be a bit misleading. My take away from Dave's comments was that there is a standards for measuring the system on the dyne and that they both have to be using the same standards. I would think it would be close.


    @Ghost LOL... Yes, there are a LOT of ways to do myself off. The key is that with my current setup, I'd like to get what I can out of it. The Hahn setup wasn't cheep all on it's own. If I'm at 250HP at the wheel now, is it possible to get to 275HP or even 300HP on the stock engine. I really have no desire to be at 1000HP, but I would like to get the most out of what I did purchase and at the moment, I don't feel as though that is the case. The system I know is capable of more, but when is it too much for the stock engine I don't know.


    Maybe @Dave@DDMWorks has some insight as to approximately how many pounds of boost in a turbo equals appropriately how many HP?


    I also believe that superchargers making their max boost at the top of the RPM range is also much easier on the engine then making that same pressure at a lower RPM like you can with a turbo. Lugging the engine and getting lots of boost pressure at lower RPM's; your just begging to blow your engine.


    Care to comment @Dave@DDMWorks?

    John
    2017 SL LE Midnight Cherry
    :COILOVERSS::TURBOSS::MOTOROILSS::FILTERSS::COLDAIRSS::DONKEYSS:

    If you’re looking for a 1/4 mile contender in the SS you’re going to be disappointed with it. At 300 hp I’m still spinning the rear wheel easily at 40-50 mph. @rabtech can spin that rear wheel at over 90, I believe, and he’s running way over the hp numbers we’re talking. Try the 4 wheel conversion. That may help some. Not sure. ?(

    Quote from jorgebri60

    If you’re looking for a 1/4 mile contender in the SS you’re going to be disappointed with it. At 300 hp I’m still spinning the rear wheel easily at 40-50 mph. @rabtech can spin that rear wheel at over 90, I believe, and he’s running way over the hp numbers we’re talking. Try the 4 wheel conversion. That may help some. Not sure. ?(

    Even NA I have spun the rear tire all the way into 4 gear

    I personally believe that by its nature the Slingshot is much better suited for road course competition than it is for the drag strip.

    Cage Free - 2016 Pearl Red SL

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    As for x boost = y horsepower, there is no perfect scale, but with most turbo/supercharger kits we have tested here, around 10 psi is close to 300hp at the wheels. With our supercharger kits, each step smaller pulley adds about 1 psi of boost and around 10-15hp at the wheels. Since a stock Slingshot will make around 150hp at the wheels and one with 10 psi of boost makes around 300hp at the wheels, that makes sense. This ratio is not a perfect one though, as our new turbo kit makes 300hp around 9psi or a little less depending on which exhaust we have on it. This ratio is also not linear, as boost increases on some of the turbo setups, your boost pressure will keep rising, but horsepower does not increase by as much. In that case, you would most likely be running into the restriction of the turbine wheel to get air out of the engine, limiting your horsepower. There is also limits of the compressor wheel to actually move more air also which can have your boost start falling off. With the supercharger, you can only spin it so fast before you reach its speed limits, and our kits with the smaller pulleys on it are at that limit already. In the power range we are talking about though (250-300hp at the wheel) the ratio works pretty good.


    On a stock engine, ARP head studs or not, I do not recommend running over 300hp at the wheels. We do know of plenty of people that have gone over that power level without any issues, but there are quite a few that needed new engines when they did. Those engine failures were from a lot of different reasons, some easily preventable, some not, but in general we always reference the 300hp number as our upper limit for someone that wants to be safe with our kits. If you want to go higher than that, that is up to you, but the majority of our customers want something they can bolt on, ride hard and never worry about and that is why we recommend the 300hp level and have also had great reliability. That being said, we have ran our stock, junkyard engine up to upper 300's at the wheels and it is still together, but if something happens to it, we can easily change it and that is the difference. Even with the higher power levels we drive, I personally like around 300hp at the wheel, I feel that is the real sweet spot for the Slingshot for track/mountain driving and around town.

    Quote from edwardaneal

    I personally believe that by its nature the Slingshot is much better suited for road course competition than it is for the drag strip.

    Absolutely, they are a lot of fun on a road course, would love to take ours out more often, hope to do it again soon.


    Obligatory track video -



    Hope that helps,
    Dave

    thanks for the video - - love it :)

    Cage Free - 2016 Pearl Red SL

    DDM Short Shifter, Sway Bar Mounts Coolant tank Master Cylinder Brace & CAI

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    For those that want to compare, I was running 115 MPH at the end of that straight with my NA Sling and that was all I could get.

    Quote from FunCycle

    For those that want to compare, I was running 115 MPH at the end of that straight with my NA Sling and that was all I could get.

    thats interesting to know. I have never had mine on a track and I have never really tried to see how fast it could go, but I have hit 100 very easily on local roads and it always seems like it could easily go much faster when I let off


    I have read that they have the top speed limited, but I do not know if that is true or just speculation

    Cage Free - 2016 Pearl Red SL

    DDM Short Shifter, Sway Bar Mounts Coolant tank Master Cylinder Brace & CAI

    Twist Dynamics Sway Bar, JRI GT Coilovers, Assault Hood Vent

    OEM Double Bubble windshields & various other goodies