Very good insight @Gnx1234. There is quite a few ways to look at this subject as you stated. Each vehicle/setup tends to be slightly different also and is best verified by a person creating a specific kit or from a local tuner that can see both AFRs and injector duty cycles.
The simplest rule of thumb my injector guys tells people for 8 cylinder boosted setups (his most popular customer) is the below...
Desired HP = injector CC IE: 600hp = 600CC injectors
Posts by TravAZ
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I have never heard of the "gimmick" story spark plugs actually running any better than stock style plugs when independently tested.
If you are changing plugs either way, than go for them if you want. Just don't expect them to outperform the stock plugs. -
Injector sizing does nothing without properly tuning your ECM.
As mentioned above, when tunes aren't custom to each machine, they tend to be programmed to run a tad richer for added safety. Heat, altitude, fuel quality, etc., etc., change from person to person and having this buffer is important.
The smell issue is more about losing the catalytic converting than the rich AFR difference in running a boosted machine. -
The post isn't specific to anyone or any one thread. There has been a lot of confusion around this subject for awhile and I wanted to try to add some clarity. There are people running boost with stock injectors, stock injectors + running 60lb secondary injectors, running 60lb only, etc, etc. It is all over the place... Hopefully this gives people some general knowledge so they can better understand injectors and what they may need for their power goals.
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I have recently been rambling about injectors in a couple of different threads and I wanted to add some clarity/links to this subject. This may help people understand what injectors do, and their importance to an engine running correctly after making modifications to boost power.
FROM - https://www.injectorsonline.co…-to-choose-fuel-injectors
Nothing will have your engine running rough faster than the wrong choice of fuel injectors. Not only that, you risk ruining your engine altogether if you make the wrong decision. So it’s important to understand the factors you need to consider when deciding which fuel injectors are right for your setup.
Bigger is not always better
It’s easy to fall into the trap of thinking that bigger fuel injectors equal more power, but unless your engine is set up to deal with the extra fuel, you’ll be on a fast track to trouble. The excess fuel will flood the engine and it either won’t run at all, or will be running too rich. This can lead to fouled spark plugs and damage to the engine.
There is a whole range of things you can do to increase your fuel capacity to accommodate bigger fuel injectors but the main ones are:
- increasing the airflow – this can be done by installing a turbocharger or supercharger, or fitting a bigger throttle body
- installing a bigger exhaust
- remapping the computer
- fitting a bigger fuel pump
- adding an adjustable fuel pressure regulator.
Running too lean
At the other end of the scale is where you’ve modified the engine but the injectors aren’t delivering enough fuel to keep up. If you’ve added a turbo, a higher flowing fuel pump, a bigger exhaust and remapped your computer, you’re going to need bigger fuel injectors. Otherwise your car will be running too lean and you’ll have a situation where your it is sluggish and lacking in power at best, or at worst, you’ll burn out the pistons and destroy the motor.
Size does matter
Both of these scenarios highlight why it’s important to have the right-sized fuel injectors. The best place to start to work out the right fuel injector size for your needs is to get an understanding of how much horsepower you expect to achieve with your modifications. We recommend you enlist the aid of a reputable car tuner to determine this.
The other critical factors are:
- whether the car is turbocharged or supercharged, and
- whether you are using E85 or standard pump petrol.
Once these factors have been established, you can use the charts below to help you select the correct injector. The following considerations should be taken into account when using these sizing charts: horsepower is at the engine (you lose roughly 30 percent if calculating from the wheels); injector duty cycle is 80 percent; and fuel pressure is 43.5 psi (3 bar).
Flow Rate Conversation Website
https://www.deatschwerks.com/flow-rate-conversion
Fuelinjectorclinic.com Flow Calculator
https://fuelinjectorclinic.com/flow-calculator
The stock Slingshot injectors are 35 lbs/hr models. The above information and Flow Calculator tool are great resources in understanding what injector should be chosen for your power goals. They are used as a rough guide and final validation comes from dynoing or street driving the machine while closely watching the injector duty cycle (software is available that does this). In almost all cases, tuners don't like to see injector duty cycles over 90% during desired AFR conditions.
Example for most forced induction kits making around 300whp... -
Save my post and look back at it when you have a chance to dyno the machine and get some input from a boosted guru in your area. I think it will make more sense at a later time.
I am not biased towards a certain kit/brand, as I have a mix of parts on my machine. The turbo kit I have currently, cannot even be purchased. I simply want to see the rest of the group get good/correct information.
Anyone can run more boost on their kit. It is as simply as changing wastegate springs or turning up a manual boost controller. The description and information should revolve around how the kit was designed and what it will do with no modifications.
Right now, it's all just super confusing and looks deceiving from my perspective...
This marketing/strategy makes a bunch more sense if it will do the number safely.
A more affordable kit capable of an exhilarating 100 whp over stock without as many risks associated with higher boost.
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Aero isn't good on the Slingshot, but what is even worse is the stock Slingshot gearing for 1/2 mile events. 5th gear is way too long and 4th gear ends right around 130 - 135mph.
So, it doesn't really matter if you have a 250hp Slinghot or a 400hp Slingshot. 5th gear will keep everyone right around that 135mph mark. Good luck picking up a bunch of MPH in 5th....
This is why Rab & Mark should absolutely crush everyone if their machines are running ok because they have ditched the stock 5 speed. But we all know how this goes... -
Display MoreJust saying....
No more needs to be said....
Drops the mic and walks off ......
I'm staying out of these debates.... last pic from the panda camp. Notice the orange redline light in the corner of the pic...
Holy Haltech lights! ha
You all better be careful if you aren't running stability control. Kites like to fly.
Hopefully someone makes the Slingshot community proud and gets over the 140mph mark. We are likely the laughing stock at these 1/2 miles events. Craziest power to weight ratio and slower than a stock $5k stock C4 Corvette.
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Cruise control for sure. Not sure where they are at on making sure the stability control and traction control work as intended. At one point it wasn't working, but I think they squared that all away.
Here is a big question... What do you really gain from the Haltech?
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Just ask him or someone close to his camp where he purchases his injectors from. Shoot the supplier a call and check. Not all "flow matched" injectors come with data sheets. Often they just flow a bunch of them and package sets of 4 close together and call it a day. "Flow matched" is a very broad description. You really want to get the % of variation at idle, 50% throttle, and 100% throttle.
I doubt your injectors are that far off. It is pretty rare so see them much over a 5% difference at 50% and 100% throttle. You are probably just seeing odd air intake volumes with the portfueler intake manifold.
The real question is, why the F would he put 60lb injectors in for secondaries? That seems really over kill and not correct. Over 400 whp Slingshots don't get close to running out a fuel with running only 60lb injectors. You have a 40lb and 60lb running together it would appear. This would mean the 60lb pulse rates would be pretty low and lower pulse rates usually show more of difference from one to another.
Lots of odd stuff going on here... -
If you guys didn't already realize from previous research/posts, Bill is an exceptional writer and maybe even a more impressive speaker. See an example below...
http://www.dragbike.com/hahn-r…eaches-another-milestone/
He is far from a dummy by anyone's standards. It is easy to understand why people would have been talked into something and regretted it later.
On a different note, make sure you really research and understand the Haltech system. A lot of people talk about it and make it sound like it is much better and more capable than the stock ECM, which really isn't the case. You lose a lot of features when you switch and you need to pay someone to tune it correctly. Unless you are built motor with a custom boosted setup / high boost, it probably makes very little sense to go that route.
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Thanks " TravAZ for the info, maybe this winter we can get a few people from the "Group
" to combine our injectors and get them flow matched. Maybe send in 3 or 4 sets at once. Probably a better change of getting more close together.
I wonder how expensive it is to just by 4 flow matched injectors? I'll have to look into that.What is the part number of the injectors? Are they just stock Slingshot injectors? If so, there are a ton of people like myself that would probably would sell them for cheap.
Around $250 for 4 injectors is the price point for the bigger 60lb ones used in the boosted stock ECM tuned configuration.
Why don't you just do yourself a favor and rip out the portfueler stuff and run the stock intake, 60lb injectors, and a Bob tune. We all know that is what is going to happen at some point anyways.
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@Casey_SS You need to find a company that specializes in fuel injectors. I think Dave is still recommending the place I use by my house called AUS Injection.
It is around $80 to send them off and have them tested. Honestly, it is much better to send out yours and a buddies and have 8 tested at the same time. Then, determine if you want them cleaned and match two pairs of 4 to the closest flow rates.
Another company that gets good reviews is Fuel Injector Clinic. Good reading at their website below...
http://fuelinjectorclinic.com/flow-testing -
Mine was a base model from 2015, so no. Sorry @Davezann.
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A 300hp Slingshot with decent tires and shocks hurts a lot of feelings at track days. Even a lot of purposed built, trailered to the track cars, can't keep up with the Slingshot.
It takes good driving too, but the vehicle itself is very capable. It is amazing how much I have to chop out of my videos, as I driving slow behind people trying to safely get around them... -
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I had the crap BOV valve, today I received the TurboSmart Supersonic. Hahn refers to it as the Billet Blow Off Valve
I only played with it for a short time as its getting to dark to be running around with the deer out there.
But at first it seemed to be set to hard. Free reeving in the garage I never go the woosh. I backed it off from the hard setting to softer settings. Then started getting some woosh. I noticed that the valve was staying open just a little prior to settling to ide. So I adjusted it a little harder. Now I get a little woosh and it seems to close at idl.
Quick road test... wow, it now stutters at full throttle which it did not do with the "stock" hahn BOV, but I got woosh.
Anybody know how to adjust it so I get smoothness back like I had with the "stock" BOV???
Thanks,
The Tial blow off valves that we run on the Alpha kits stay open at idle around 1/8 of an inch. They also use a 10psi spring.
https://www.jegs.com/i/Pro-Dia…LvpnqSX-I2CQaAsLXEALw_wcB -
But, you would still need to re-paint or re-powder the wheel too, right?
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@SaltyClownNY You need to figure out what is dripping off that spark plug. That isn't normal and is not good. Is it fuel, oil, or coolant?
Not sure if you have ever seen this, but it is a good old read that relates to spark plugs and Slingshots.
https://www.slingshotforums.co…un-with-spark-plugs.8603/
From this info and my experience with a couple of different Alpha Turbo kit, I have chosen the below spark plug to be best for my setup.
https://www.jegs.com/i/Brisk-USA/084/RR14S/10002/-1
This is what I used to run...
https://www.ngk.com/product.aspx?zpid=30369
Make sure to note that both plugs are two steps colder than the stock plugs. 1 step colder is probably just fine too.
Also, forged motors/blocks don't necessarily always run less compression (pressure) than a stock block. It depends what you put into the engine and how you build it. My old built motor was setup to run a compression ratio of 9.5, compared to the stock 10.4 compression. Just because someone is running a forged motor, it doesn't mean they made the right choices in lowering the compression and opened up the piston ring gaps.
I would agree the PCV issue is the main issue causing smoke and should be included in all Port Fueler kits. The varying exhaust back-pressure probably makes certain setups worse, but they all likely would benefit from a PCV setup as stock intended. I am sure the Welter has quite a bit of back pressure from the length and size of the pipe. I can see a small difference on power and detonation on the Alpha turbo kit from changing the side exhaust to their race exhaust. -
I am just happy you guys are happy. I don't own this kit and probably wouldn't recommend it (unless used at a great price), especially with the Port Fueler setup.
Hopefully all of the issues are squared away and you guys have good luck on the tuning side for the Port Fueler setup!
Boost away!
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1. I highly advise against putting anything larger than a 285/35/20 tire on a stock 9 inch wide wheel. It is too far out of recommendation and the tire is considerably bulged. They last thing anyone needs is the tire de-beeding under extreme use.
2. Widening a stock wheel makes very little sense. The stock wheels aren't that nice to start with and it is expensive compared to other options. If you widened the wheel 2 inches to a 11 inch rear wheel, you would be inch too far towards your shock. This would mean that you need a big 1 inch spacer and new wheel studs or a spacer that converts to new lug studs.
3. The best matches for a rear wheel are likely...
- The Rohana RFX5 you listed about
- The XO Verona (found here -https://www.xoluxurywheels.com…rona-xo-custom-wheels.php)
4. If you want wide, just run what everyone else runs - 20x12 rim (one of the two above) and a Toyo T1R 345/25/20 tire
5. I have a black Rohanna RFX5 with setup listed in #4 for sales if your interested - shipping probably isn't favorable though...
