Lets talk Aux fueling.. Shotgun or PI?

Clean WHP

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Apr 24, 2017
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Whats up guys, I cant make a decision on which kind of aux fueling I want to go with and its driving me nuts! My car will be running a VIE top mount with a Garrett GTX 3582R gen 2 1.06AR and my goal is 700WHP or so. I will be staying stock motor and Dont want to risk blowing it so therefore probably only running 27-28psi max.

I have never seen someone run the GTX3582R gen 2 on an N54 so not sure how much power to expect at 27-28 PSI. Im hoping the 1.06AR gets me some extra power up top but once again im not sure. I could see it making anywhere from high 600's to low 700's at the wheels.

I will be going with a dw400 pump for the LPFP, and I will be going full flash with boostbox. Now Im trying to decide if I want to add PI or go with a shotgun (single or double).

Single shotgun:
  • costs slightly less than PI when u factor in the price of PI + controller.
  • could probably supply my WHP goal when on e50 ish fuel and being fed by the dw400 lpfp.
  • is safer than PI
  • my local e85 pump has both 93 and e85 at the same pump, so mixing is not a huge deal.
  • on the downside it could cause my hpfp to go out quickly, but im not too worried about that since I could take the FCP euro route on the next hpfp.

Double Shotgun:
  • can supply my WHP goal with full e85 (a bit more convenient that mixing and perhaps a bit safer with being higher octane than say e50 at 700whp?)
  • is safer than PI
  • downside is the price is hella expensive and it needs a controller for hpfp which if ive buying a aic6 controller anyways I feel like i may as well just go port injection

Port Injection:
  • can support my WHP goal on full e85
  • said to be unsafe and risky due to PI controllers not being that great
  • priced decently for a set up that can run full e85 at 700whp (much cheaper than double shotgun)

Whats everyone's opinion and how likely am I reach my goal with a dw400, single shotgun, and E50?
 

langsbr

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Apr 5, 2017
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My suggestion is always DI over PI. I would go wit the single barrel and if you get to your goal, perfect. If you are shy of it just from fueling, you can determine then if you want to drop the extra cash to get there. If you hit 650whp and run out of fuel, you may determine its worth doing. If you hit 690, you might be content.

There's been a number of people cresting 600whp on just the stock HPFP on an Emix, so I would think the single barrel will get you there, might have to be a little less ethanol though, maybe E40.

On a related note - I know the Gen2 is supposed to spool better, but the 1.06AR seems fairly large. Won't that kill some spool?
 

Clean WHP

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Apr 24, 2017
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My suggestion is always DI over PI. I would go wit the single barrel and if you get to your goal, perfect. If you are shy of it just from fueling, you can determine then if you want to drop the extra cash to get there. If you hit 650whp and run out of fuel, you may determine its worth doing. If you hit 690, you might be content.

There's been a number of people cresting 600whp on just the stock HPFP on an Emix, so I would think the single barrel will get you there, might have to be a little less ethanol though, maybe E40.

On a related note - I know the Gen2 is supposed to spool better, but the 1.06AR seems fairly large. Won't that kill some spool?

thanks for the reply. I would be fine with a tad under 700whp (say 675-700) i dont need the magic number on the dyno, so im leaning towards single shotgun.

lots of people have differing opinions on spool vs AR size. Personally, I think a 1.06 will be just fine, and the gains on the top end will be well worth it. I know its a completely different platform and a rotary engine all together, but check this video of Rob Dahm and his switch in AR housing on a beastly 3 rotor rx7. Basically he went up a shitton of AR sizing and did not loose any spool, but deceased his back pressure and increased his top end. skip to the 9:10 mark for the graphs
 

dyezak

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DI>PI>TBI>Carburetor

This is a fact and undisputable. The only question is do you want to incur the expense and hassle required to stay full DI?
 

langsbr

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Apr 5, 2017
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Normally I'd say the platform doesn't matter, but with a rotary, all bets are off. They inherently use a larger a/r from what I've seen. They're like weird crazy air pumps. Speaking of air pumps the only good use for a rotary is an air compressor, lol. The larger AR works because a 3 rotor is equivalent to 5.8l piston engine! Not my math, see here https://oppositelock.kinja.com/comparing-piston-and-rotary-displacement-1139838430

It's always good to see different setups so I'm not saying don't go with that AR, just be mindful that it may not perform how you expect and definitely not similar to a wankel. Wankels should be placed where they belong - the trash
 
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MDORPHN

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FWIW, I'm now planning to change the turbo and fueling on my MOTIV 750'd 1M to eliminate the PI and to gain faster spool/improved transient response since my 1M is used primarily on road race courses.

I'll be replacing my HTA3586r with a smaller turbo (GTX 3076r, GTX 3576r, XR7164, or XR7865) .82 AR and may go single shotgun so I can run 40-50% E85 with some headroom.

My hp goals are lower than the OP and I'm shooting for 550 whp +/- 25 or so.

Neil
 

Clean WHP

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Apr 24, 2017
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Thanks for the info. I get that the 3 rotor flows a massive amount of air, and thanks for pointing it out that it is equivalent to a 5.8L, (thats actually wild) but in the video the AR was changed from a 1.28 or so to a 1.44 AR!! even though its a 3 rotor, and equivalent to a 5.8L and can move a shit ton of air, 1.44 is still a massive AR.

You dont see LS builds running anywhere close to 1.44AR or atleast I never have. I know the wankel moves a ton of air, but still.

I dont think the 1.06 wont be laggier, but I believe the lag will be minimal. Its still a GTX gen 2 3582R, and is still an incredibly fast spooling turbo. We shall see what it does and If I'm not satisfied with the 1.06 I can always swap it out later!

My only concern is if the single barrel will support my WHP goals on e40/e50 combined with a dw400 feeding it from the lpfp side of things. Maybe I will just have to find out

Would love if someone running single barrel is out there and could chime in
 
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dyezak

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Thanks for the info, If im not satisfied with the 1.06 I can always swap it out later.

My only concern is if the single barrel will support my WHP goals on e40/e50 combined with a dw400 feeding it from the lpfp side of things. Maybe I will just have to find out

Would love if someone running single barrel is out there and could chime in

Call Vargas.
 

veer90

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What's all this talk about port injection being unsafe... been pushing 30 psi on e85 for a while and have yet to blow up my motor.

PI is only unsafe when you go full retard and keep your foot on the floor when it misfires.
 
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noshi

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Apr 25, 2018
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I contemplated the same thing when I finished my single install, and came to the conclusion to just tune a solid 93 Oct map and see where that nets me. I came to this conclusion since I rather a solution that swaps out the original pump, and not add to much fuss to my setup.

Going port injection or shotgun seems like I'm applying a temporary fix, and loosing mod money on a solution that I know I would drop the instance a direct pump replacement was introduced. Though I would love the benefits of not walnut blasting anymore, using port injection.

I've swapped my motor already so i lean a bit more on the cautious side. Fun experience but don't plan another swap till its a built motor lol.

But if i was to say "screw all that I want more power now!", i'd go port injection. Since I wouldn't have to worry about walnut blasting, easier install and reversibility. Also if a solution to swap out the original pump is released, I have a better resale value (controller | injectors). Anyways that's just my train of thought.
 

Clean WHP

Corporal
Apr 24, 2017
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2010 135i Msport 6MT
I contemplated the same thing when I finished my single install, and came to the conclusion to just tune a solid 93 Oct map and see where that nets me. I came to this conclusion since I rather a solution that swaps out the original pump, and not add to much fuss to my setup.

Going port injection or shotgun seems like I'm applying a temporary fix, and loosing mod money on a solution that I know I would drop the instance a direct pump replacement was introduced. Though I would love the benefits of not walnut blasting anymore, using port injection.

I've swapped my motor already so i lean a bit more on the cautious side. Fun experience but don't plan another swap till its a built motor lol.

But if i was to say "screw all that I want more power now!", i'd go port injection. Since I wouldn't have to worry about walnut blasting, easier install and reversibility. Also if a solution to swap out the original pump is released, I have a better resale value (controller | injectors). Anyways that's just my train of thought.

very nice insight. I like the point you made about walnut blasting, and resale value. plus install on PI is super easy and it would allow me to run full E.

Honestly It might just come down to whatever I can find the best deal on. If i can score a used AIC6 controller and maybe a discount on a BMP PI kit or just a good PI kit used, that may be the route I take cause I know I can re-sell it and ditch it if something better arrises
 
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chadillac2000

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I've been contemplating this for the better part of a year now waiting for an upgraded HPFP to come out, but it doesn't seem to be happening.

Since I'm not going for sky high HP numbers, keep my maintenance up to date, pay close attention to logs and replace ignition components on a regular basis, I finally bit the bullet and picked up on of the Phoenix Race intake manifolds with PI combo. It's been said before, but it seems port injection gets a bad reputation as a motor killer, when it's probably people not paying attention to maintenance/logs, and staying in it when they feel the first misfire. The JB4 controller seems to have a lot more safeties in place than others as well as far as shutting things down at the first sign of a misfire so it can be diagnosed.

I'm going to replace my HPFP too since it's getting weak and I don't want that acting up after all this. Plus I have 100,000 miles on the thing. More than likely going to need to upgrade my stage 2 bucket to a stage 3 bucket on the LPFP side.
 
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chadillac2000

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very nice insight. I like the point you made about walnut blasting, and resale value. plus install on PI is super easy and it would allow me to run full E.

Honestly It might just come down to whatever I can find the best deal on. If i can score a used AIC6 controller and maybe a discount on a BMP PI kit or just a good PI kit used, that may be the route I take cause I know I can re-sell it and ditch it if something better arrises

I imagine Jake will have a BMP kit up for sale used soon as he got in on the DocRace manifold + PI combo.
 

martymil

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Is @martymil around? I know he runs a shotgun. He may have good insights.


We are runnning 27-28 psi on a gtx 3584rs with a .82 and a 1.01 housing to see which one works best and full testing is still a month away if you can hold off

We ran pi on this setup alone and we maxed the pi out and added a shotgun to supplement the pi as the pi could not supply enough fuel on spool but we are adding a double barrel to minimize the use of pi altogether but from experience we still have to run some pi

We made 460rwk on a dyno dynamics which is a heart breaker dyno compared to the ones you guys use

With 416rwk I ran 130mph trap speeds
With 460rwk it should be 134mph +

This is just an indicator for how much our dynos differ to you guys but trap speeds never lie
 
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MDORPHN

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Jan 28, 2018
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very nice insight. I like the point you made about walnut blasting, and resale value. plus install on PI is super easy and it would allow me to run full E.

Honestly It might just come down to whatever I can find the best deal on. If i can score a used AIC6 controller and maybe a discount on a BMP PI kit or just a good PI kit used, that may be the route I take cause I know I can re-sell it and ditch it if something better arrises

I may be selling my AIC6 and MOTIV PI kit shortly...

Neil
 
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dyezak

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What's all this talk about port injection being unsafe... been pushing 30 psi on e85 for a while and have yet to blow up my motor.

PI is only unsafe when you go full retard and keep your foot on the floor when it misfires.

It's not just about safety, it's about performance, efficiency, and quality as well. The automotive industry moved from a carburetor to throttle body injection because TBI was better all around than the carb. We moved from TBI to port injection because PI was all around better. And we moved from PI to direct injection because DI is all around better.

And just like the PI revolution...where people couldn't figure it out for the longest....and they went back to carburetors. We are experiencing the same exact thing now. DI is better, but people are having trouble figuring it all out, so right now reverting back to PI (that we understand and can control) is the stop gap solution. And there's nothing really wrong with that, but lets all be honest about it. We aren't using PI because it is the better solution. We are using PI because we don't have full control of DI yet.
 

The Convert

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FWIW, I'm now planning to change the turbo and fueling on my MOTIV 750'd 1M to eliminate the PI and to gain faster spool/improved transient response since my 1M is used primarily on road race courses.

I'll be replacing my HTA3586r with a smaller turbo (GTX 3076r, GTX 3576r, XR7164, or XR7865) .82 AR and may go single shotgun so I can run 40-50% E85 with some headroom.

My hp goals are lower than the OP and I'm shooting for 550 whp +/- 25 or so.

Neil
I'm actually contemplating the same thing and same power goals. Keep us posted on your build and results.
 

Stucks

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Nov 3, 2016
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DI is better, but people are having trouble figuring it all out, so right now reverting back to PI (that we understand and can control) is the stop gap solution. And there's nothing really wrong with that, but lets all be honest about it. We aren't using PI because it is the better solution. We are using PI because we don't have full control of DI yet.

+5000