Forced Induction: Whipple or Twins

[Max97COBRAtkd]

It seems this topic is almost taboo in the GT350 world so I would like to bring it up. I see quite a few Whipple GT350's on Instagram making great numbers. I don't see many of the Hellion twin kits out there. I doubt it's just because of cost though. Here's what I see as far as pros/cons:

Whipple: More power, helps with lack of torque down low, need beefed up timing components, oil pump gears, etc to help the flat plane crank take the extra stress. Heat soak is the real demon here, especially if you track it.

Hellion Twins: more power, goes perfectly with the way the motor works already, extra engine bay heat, but won't heat soak nearly as quick as a Whipple, especially on really low, say 5psi boost. I honestly don't see anything wrong with it and it could only help track times, whether on the strip or road course. I am a rookie so you are welcome to school me on road courses.

I see these things making great power on really low boost and crazy high power on high boost. Now, I know warranty comes into play here too. No way I would void my warranty to do this personally. Once it's up though, time to play so just curious on opinion on this from current owners of all three, N/A, Whipple, & Hellion Twins.

Hoping to get in a GT350 soon myself so I need to learn myself on this new platform. Going to test drive one with 3k miles on Friday. Super excited.

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[ANGREY]

Some other considerations:

1) The whipple option also presents the challenge of the hood and clearance. It's resolved (bandaid) by using lowering engine mounts, but for those already concerned about ground clearance, it's basically just dropping the powertrain lower so it'll fit under the hood. I have yet to see an aftermarket hood/top side solution.

2) Turbos are gonna give you a heat source regardless of the boost you run. Lower boost is simply a function of wastegate and running the exhaust through hair dryers is going to create a heater, low boost or not. This is where heat shielding helps with turbos.

3) Turbos change the character of the exhaust note. For those of us that love/cherish the way a V-8 sounds, adding hair dryers definitely tames/restricts it (to a noticeable degree). Maybe that's good or bad for you, but the whine of a twin screw and the exhaust note are going to be appreciably different than twins. This probably has to do with the fact that you can still run long tubes with the twin screw setup (which make the car sound glorious).

4) Twins seems a bit of a solution to a problem that doesn't exist. The car has plenty of top end go, it's just the low end response that most driver's don't like. Most of us are used to the glorious torque and the ability to be in 6th or 5th at low rpm and feel the car respond when asked. THAT seems to be the biggest complaint of the high revving FPC voodoo motor. You don't hear a lot of guys complaining about running out of ponies at full wail. Turbos would help a LITTLE on the lower end, but not much (especially if you go big hair dryers).

5) I know over the years that "turbo lag" has been reduced greatly, but it's still there. Granted, as you point out, the power band of the Voodoo kinda mimics turbo lag, but the twin'd cars I drove (even though they're better than the old big singles) still made me frown because the responsiveness and sudden run up felt jerky.

6) I guess it all depends on what you're trying to "solve." Some people like how turbos make the car pedestrian at normal driving conditions with the added getup at WOT/high rpms. But as I've stated above, I think most guys who add a power adder are looking to resolve the biggest knock against the voodoo which is low end seat dyno numbers. If you're just looking for a street/roll race monster, then twins is a better option. If you're looking to have more low end response then twin screw is definitely the ticket. Neither is going to appreciably improve it's track capabilities/characteristics. The turbos aren't going to mess with the balance as much as the TS by putting 60 extra lbs on the front. But both are going to add to overheat/limp worries. Are turbos really going to help with entries and exits in the turns? A twin screw setup might, but as you pointed out, it doesn't do much good to improve your lap times if you can only run a few laps before heat injury. And even then it's an assumption that the added weight and worse balance doesn't negate the added torque.

I've thoroughly researched and thought this whole aspect through and I'm still not TOTALLY decided but I've leaned back toward just leaving the car N/A. If I want a street/strip beast I'll get a different vehicle which is MUCH more suited to it.

 

[Max97COBRAtkd]

Some other considerations:

1) The whipple option also presents the challenge of the hood and clearance. It's resolved (bandaid) by using lowering engine mounts, but for those already concerned about ground clearance, it's basically just dropping the powertrain lower so it'll fit under the hood. I have yet to see an aftermarket hood/top side solution.

2) Turbos are gonna give you a heat source regardless of the boost you run. Lower boost is simply a function of wastegate and running the exhaust through hair dryers is going to create a heater, low boost or not. This is where heat shielding helps with turbos.

3) Turbos change the character of the exhaust note. For those of us that love/cherish the way a V-8 sounds, adding hair dryers definitely tames/restricts it (to a noticeable degree). Maybe that's good or bad for you, but the whine of a twin screw and the exhaust note are going to be appreciably different than twins. This probably has to do with the fact that you can still run long tubes with the twin screw setup (which make the car sound glorious).

4) Twins seems a bit of a solution to a problem that doesn't exist. The car has plenty of top end go, it's just the low end response that most driver's don't like. Most of us are used to the glorious torque and the ability to be in 6th or 5th at low rpm and feel the car respond when asked. THAT seems to be the biggest complaint of the high revving FPC voodoo motor. You don't hear a lot of guys complaining about running out of ponies at full wail. Turbos would help a LITTLE on the lower end, but not much (especially if you go big hair dryers).

5) I know over the years that "turbo lag" has been reduced greatly, but it's still there. Granted, as you point out, the power band of the Voodoo kinda mimics turbo lag, but the twin'd cars I drove (even though they're better than the old big singles) still made me frown because the responsiveness and sudden run up felt jerky.

6) I guess it all depends on what you're trying to "solve." Some people like how turbos make the car pedestrian at normal driving conditions with the added getup at WOT/high rpms. But as I've stated above, I think most guys who add a power adder are looking to resolve the biggest knock against the voodoo which is low end seat dyno numbers. If you're just looking for a street/roll race monster, then twins is a better option. If you're looking to have more low end response then twin screw is definitely the ticket. Neither is going to appreciably improve it's track capabilities/characteristics. The turbos aren't going to mess with the balance as much as the TS by putting 60 extra lbs on the front. But both are going to add to overheat/limp worries. Are turbos really going to help with entries and exits in the turns? A twin screw setup might, but as you pointed out, it doesn't do much good to improve your lap times if you can only run a few laps before heat injury. And even then it's an assumption that the added weight and worse balance doesn't negate the added torque.

I've thoroughly researched and thought this whole aspect through and I'm still not TOTALLY decided but I've leaned back toward just leaving the car N/A. If I want a street/strip beast I'll get a different vehicle which is MUCH more suited to it.

Thank you for the very thought out response. I have had a turbo Terminator before so I know how they change the feel of the car. I honestly didn't like it. Made cool noises and was fast up top though.

Your point on exhaust note is spot on and that is a MAJOR consideration with these cars. I won't track mine but maybe once per year depending on my schedule. It may make sense later for me to go Whipple possibly but I'm for sure going to enjoy the shit out of the car for a while in semi-factory form. If I do get the one I looked at yesterday, it will get a carbon fiber R wing, stripe delete, MGW shifter, and resonator delete asap. They sound so stupidly amazing in person and behind the wheel.

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[PhoenixM3]

Thank you for the very thought out response. I have had a turbo Terminator before so I know how they change the feel of the car. I honestly didn't like it. Made cool noises and was fast up top though.

Your point on exhaust note is spot on and that is a MAJOR consideration with these cars. I won't track mine but maybe once per year depending on my schedule. It may make sense later for me to go Whipple possibly but I'm for sure going to enjoy the shit out of the car for a while in semi-factory form. If I do get the one I looked at yesterday, it will get a carbon fiber R wing, stripe delete, MGW shifter, and resonator delete asap. They sound so stupidly amazing in person and behind the wheel.

Sent from my Pixel 2 using the svtperformance.com mobile app

If I were you, I’d get the car, drive it for a year, then evaluate the modification path ahead. For me, I’d do the same, but feel I’d lean towards bolt-ons and a tune.

I also feel that the GT350 = kickass cage fighter where a GT500 = Heavy weight boxer. You can try to cross-breed them, but the results usually compromise each thoroughbred’s original DNA.

 

[SID297]

The Whipple will be far simpler and more reliable. Hellion will make far more power. Both can make the VooDoo splatter it guts.

 

[mavisky]

An option you left off that one of my friends swears by is his Vortech kit. Doesn't fix the low end torque issue, but has a smooth power delivery that matches the Voodoo engine just at a higher horsepower level.

Of course I'm also friends with the boys over at Fathouse and their twin kits are mean as all get out.

 

[SID297]

An option you left off that one of my friends swears by is his Vortech kit. Doesn't fix the low end torque issue, but has a smooth power delivery that matches the Voodoo engine just at a higher horsepower level.

Of course I'm also friends with the boys over at Fathouse and their twin kits are mean as all get out.

Those kits look top notch.

 

[Voltwings]

If you try to track your car with twins you're going to have a very bad time. If you try to track your car with a whipple you'll have a pretty bad time.

Not to be shitty, but amateurs, roadcourses and more power than one knows how to handle do not mix. I've seen more than one "muscle car" go off track because the owner was just out there drag racing between the straights and was not properly equipped, physically or mentally, for the turns.

Had a guy in an 800 whp supercharged camaro plow right off track at well over 100 mph after missing a turn. Car was totaled and he went home in an ambulance. I'd STRONGLY recommend a few track weekends under your belt before even remotely considering a power adder.

Now, let's assume you were capable of competently handling the power, I think you're vastly underestimating the heat and weight-over-the-nose headache you're bringing on yourself.

 

[Max97COBRAtkd]

You are totally correct Voltwings and I 100% agree. However, MOST people that would go forced Induction with these cars would only be driving them on the street and maybe dragstrip. I highly doubt that very many people go forced induction on a GT350 that track their car regularly.

After driving my GT350 for a week or so after coming from my 756/682 Cobra, I am actually quite happy with it and would consider going even more gear to a 4.56 over my 4.09's and do full bolt ons (Longtubes, full exhaust, intake, tune, etc) before I would go with a Whipple. Just my opinion. The gears make this thing so much more fun over a stock GT350!

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[blueovalkid]

I have a Whipple on my GT350 with the lowered motor mounts and I dont have any ground clearence issues.
I have the FRPP springs as well

 

[tt335ci03cobra]

Twin 55’s would hit hard with 1/4 throttle above 4000rpms in a gt350.

Me? I’d keep the ethos of the gt350, and go e85, full bolt ons, tune and 4.10-4.30 gears.

Car traps 117+ stock, and could do 125+ with those changes. That’s hellcat straight line performance.

A whipple after that is 150mph capable, and very safe because of e85. That said, the whipple is good for around 80-100whp/wtq until you hit 6000rpms, then it really starts to run up the difference vs stock. Spooled, the turbos will feel much faster at 5000rpm than the whipple will since the air difference and force is entirely different. Turbo gt350’s show closer to 200whp/wtq at 5-6500rpm but start to flatten off uptop from 7000-8000. I’ll post some pics.

Supercharged at Hennessy with iirc a whipple.

Turbo from hellion.

Sorry but the guy saying the turbo would take forever is incorrect as these graphs clearly show. The sc combo is only having to make it to 8 psi while the turbo car made 18psi just fine very quickly. Table flat power curve on 18psi with over 1150whp. It’s just useless power in a street car though. I’d personally set it to 5psi and forget it.

Anyways much as turbo is my personal favorite on anything, the gt350 is too fun na and revving out peaky like an s2000 or brz but with balls and a v8 soundtrack. Throw bolt ons and gear, and it’s insanely fun. After that too easy to just go to a nice whipple. Save the turbos for a different build imo down the road with a cpc crank.

I did 62’s on my 5.3 bbs build for my 03 cobra and love everything about that build to give you an idea of how much I like turbos. That said I plan to follow the route I just laid out when I get around to a gt350

 

[ANGREY]

Running 18 psi on any motor at 12:1 compression is just asking for trouble. ANY motor. Let alone one as optimized from the factory for N/A (aluminum pistons, membrane thin cylinder liners, significant balancing challenges, etc).

Can you fit 10 people in a 12' aluminum boat? Sure. Sitting next to the dock. Would you want to take it out and use it in all sorts of applications that way? Probably not.

If you compare apples/apples (i.e. same boost level) even twins are going to have spooling challenges (i.e. lag) compared to a twin screw. That's kinda the point of the twin screw, to bring on torque instantly and low. As I said earlier, turbos and their run up kinda mimics the power distribution of the voodoo already. So basically solves a problem that doesn't exist. MOST of the guys wanting "more" are wanting it down low where the car feels doggy. Especially in highway scenarios involving 5th and 6th gear. For the first few trips, I found myself annoyed that I couldn't just mash the gas at 2k rpms and pass people. The car isn't built that way. Now I just down shift and go.

Considering the costs, the inherent drawbacks and the reliability concerns, creating a street/strip monster out of a 350 is kinda like trying to make a Porsche go off roading. Can it be done? Sure. Probably not the best starting platform though.

 

[tt335ci03cobra]

Ya you’re wrong, sorry.

8 psi on 55’s (turbo) on a voodoo has much more mid range power than a whipple. You don’t understand physics. If you spec 62’s or 67’s you’d have a point. But that’d also make 1200whp on 12psi.

Any supercharged combo will have far less midrange at the same boost as a turbo car, period.

I’ll find a pic of a gt350 on low boost to show you that you are incorrect.

I’ve built and owned nitrous, sc, and turbo modulars.

That all said, I’d go na then sc on this motor, and honestly skip the whipple for a centri.

 

[tt335ci03cobra]

Once boost is built, which takes half a second, a turbo voodoo will be at peak boost. No belt slip, no parasitic drag.

8psi in an engine that needs air down low is much better served via turbo than in a form that eats power via crank drag and possible belt slip. Also, most pd blower combos can’t rev high enough to keep up with the engine speed.

Again, it’s just much easier to put a $5-6k blower on this car vs buy a $10k turbo kit and install it.

Spooling twin 55’s with a voodoo isn’t hard at all. 4.6L modulars making 300tq we’re fitted with turbo kits centered on 50’s and then 57’s 10+ years ago. The cars with 50’s fully spooled quickly, but people wanted more powers. All of the powers. Some kits were centered around 61’s.

I have a much peakier combo than a voodoo, and am running an out dated ecu. I have stage 3 ported gt500 heads and aggressive stage 3 turbo cams from MMR, as well as 9.3/1 compression, and 62’s in a T4 flavor. Manual transmission, very long 24”+ cold side. Read: very laggy combo on paper. Much more so than a voodoo (has milder cam profile, better low and medium airflow head design, much higher compression, only .1L smaller, etc etc than I have).

My combo makes 10psi by 4000rpm. Just rolling onto my gas pedal wot in 3rd at 3000rpm, I have 5+ psi. and can jump from 50 to 115mph in a few seconds on pump gas with 15 year old parts.

Turbo Voodoo’s are snappier than my old stuff, and can rev to 8000rpm. My combo is limited to 7000-7500rpm until I convert to a stand alone computer. I’m running scaled tables with 96% fuel trim on my 30psi tune. Incredibly inefficient.

Here’s some media of low boost turbo gt350 action. Enjoy


^clearly states it had low end torque, spools fast etc etc

 

[ANGREY]

Some people just want to ice skate uphill.

Fine, you're right I'm wrong. Turbos are better for LOW END (LOW END LOW END, not midrange LOW END) torque. Tell all your friends. You'll still be wrong. But tell them all that turbos make more torque at low rpms.

Anyone who's driven a new Raptor will disagree with you as well, but tell them anyway.

Turbos are great in certain aspects, but they don't beat displacement or positive displacement boost for low end torque.

Unless you're sizing the tiniest turbos in the world to spool at 1000 rpm, (which no one does) turbos have lag. That's the tradeoff. Having enough huff up high to make the desired power and not taking forever to spin up to get there.

Why do you rarely see turbos on an offroad crawler (if ever)? Because they want to operate below 3k rpms where MOST turbos aren't very helpful.

 

[Curt@injected]

Some other considerations:

1) The whipple option also presents the challenge of the hood and clearance. It's resolved (bandaid) by using lowering engine mounts, but for those already concerned about ground clearance, it's basically just dropping the powertrain lower so it'll fit under the hood. I have yet to see an aftermarket hood/top side solution.

2) Turbos are gonna give you a heat source regardless of the boost you run. Lower boost is simply a function of wastegate and running the exhaust through hair dryers is going to create a heater, low boost or not. This is where heat shielding helps with turbos.

3) Turbos change the character of the exhaust note. For those of us that love/cherish the way a V-8 sounds, adding hair dryers definitely tames/restricts it (to a noticeable degree). Maybe that's good or bad for you, but the whine of a twin screw and the exhaust note are going to be appreciably different than twins. This probably has to do with the fact that you can still run long tubes with the twin screw setup (which make the car sound glorious).

4) Twins seems a bit of a solution to a problem that doesn't exist. The car has plenty of top end go, it's just the low end response that most driver's don't like. Most of us are used to the glorious torque and the ability to be in 6th or 5th at low rpm and feel the car respond when asked. THAT seems to be the biggest complaint of the high revving FPC voodoo motor. You don't hear a lot of guys complaining about running out of ponies at full wail. Turbos would help a LITTLE on the lower end, but not much (especially if you go big hair dryers).

5) I know over the years that "turbo lag" has been reduced greatly, but it's still there. Granted, as you point out, the power band of the Voodoo kinda mimics turbo lag, but the twin'd cars I drove (even though they're better than the old big singles) still made me frown because the responsiveness and sudden run up felt jerky.

6) I guess it all depends on what you're trying to "solve." Some people like how turbos make the car pedestrian at normal driving conditions with the added getup at WOT/high rpms. But as I've stated above, I think most guys who add a power adder are looking to resolve the biggest knock against the voodoo which is low end seat dyno numbers. If you're just looking for a street/roll race monster, then twins is a better option. If you're looking to have more low end response then twin screw is definitely the ticket. Neither is going to appreciably improve it's track capabilities/characteristics. The turbos aren't going to mess with the balance as much as the TS by putting 60 extra lbs on the front. But both are going to add to overheat/limp worries. Are turbos really going to help with entries and exits in the turns? A twin screw setup might, but as you pointed out, it doesn't do much good to improve your lap times if you can only run a few laps before heat injury. And even then it's an assumption that the added weight and worse balance doesn't negate the added torque.

I've thoroughly researched and thought this whole aspect through and I'm still not TOTALLY decided but I've leaned back toward just leaving the car N/A. If I want a street/strip beast I'll get a different vehicle which is MUCH more suited to it.

Those freaking lowered engine mounts combined with the flat plane crank absolutely suck.

I've built, tuned and driven all three. My personaly preference is the whipple despite the nvh issues with the lowered mounts. The twins with 55mm exhaust housings do spool really quick though I just prefer the more linear and predictable power band of the whipple myself.

It really depends on what you plan to do with the car. For a street car whipple all day. If you're going to build a roll race monster with a built engine etc then turbos. Road course car I'd keep it na.

 

[Curt@injected]

Some people just want to ice skate uphill.

Fine, you're right I'm wrong. Turbos are better for LOW END (LOW END LOW END, not midrange LOW END) torque. Tell all your friends. You'll still be wrong. But tell them all that turbos make more torque at low rpms.

Anyone who's driven a new Raptor will disagree with you as well, but tell them anyway.

Turbos are great in certain aspects, but they don't beat displacement or positive displacement boost for low end torque.

Unless you're sizing the tiniest turbos in the world to spool at 1000 rpm, (which no one does) turbos have lag. That's the tradeoff. Having enough huff up high to make the desired power and not taking forever to spin up to get there.

Why do you rarely see turbos on an offroad crawler (if ever)? Because they want to operate below 3k rpms where MOST turbos aren't very helpful.

The 55 mm turbos actually do make more torque than the whipple from 3500-6500 by quite a bit with far less boost. There is still some inevitable lag but you'd be surprised by how fast they actually spool in this combo. On the street the lag is even less noticeable than it is on the dyno.

 

[ANGREY]

The 55 mm turbos actually do make more torque than the whipple from 3500-6500 by quite a bit with far less boost. There is still some inevitable lag but you'd be surprised by how fast they actually spool in this combo. On the street the lag is even less noticeable than it is on the dyno.

I know they've come a LONG LONG way since the old days where the car felt like a black powder musket (fire...wait, recoil) but my point to him was there's a reason that twin screws still exist. Turbos are superior in just about every other aspect, the one area they still aren't tops is low end torque/response. That's improved greatly, and I'm sure that guys wanting to have the best of both world's can do a 50 shot on the low end to bridge the lag, but then it's all the hassle/fuss of running nitrous and one of the selling points of a lot of turbo setups is being able to be "pedestrian" at normal/low rpms and then having it wake up when called upon.

 

[Curt@injected]

I know they've come a LONG LONG way since the old days where the car felt like a black powder musket (fire...wait, recoil) but my point to him was there's a reason that twin screws still exist. Turbos are superior in just about every other aspect, the one area they still aren't tops is low end torque/response. That's improved greatly, and I'm sure that guys wanting to have the best of both world's can do a 50 shot on the low end to bridge the lag, but then it's all the hassle/fuss of running nitrous and one of the selling points of a lot of turbo setups is being able to be "pedestrian" at normal/low rpms and then having it wake up when called upon.

You are correct. This is why I still prefer the whipple just because of how linear the power band is but that kit does spool crazy quick. It works well for those who choose to go turbo.

 

[tt335ci03cobra]

If you want 450wtq at 2300rpm instead of 350wtq at 2300rpm, then yes, the whipple will feel a little more powerful than the turbo car at 2300rpm.

Angry, you are correct on that.

I assumed you meant low rpm as 2-4k, mid as 4-6k and high as 6-8k.

If your saying the whipped will have more torque at 2-3krpm and the turbos have more torque and power from 3k to 8k, then I agree with you.

I’ve had one combo that everyone said would be killer. I put 57’s on a 5.4 with stock 03 cobra heads and cams. It made 600wtq around 2500rpm, over 900wtq at 4K and peaked at 900whp at 6k.

I would routinely spool it up at very low rpm. Melted #8 cruising at 40mph in 3rd gear around 1800rpm. Too much crank case pressure and cylinder pressure.

Engines don’t want or like high pressure low rpm conditions. They can’t expel what’s there, this creates higher cylinder temp and can lead to pre ignition.

I’ve been in whipple gt350’s, they aren’t gt500’s at 2k rpm, but man are they screaming up top. I’d say a whipple gt350 feels so fun because it keeps the linear feel of what you’d assume a gt350 feels like. When you drive a gt350 you realize it’s set up for midrange punch much more so than peak power. They left 50 peak hp on the table to widen and fatten/stretch the midrange. The whipple gives you the factory experience you expect.

It’s clear in these graphs. Stock vs whipple

The sc only nets 75-100wtq at very low rpm. It fully fills the chambers at peak rpm. The parasitic nature of the blower as well as the cam profile makes a whipple feel like a rotex or centri on these cars. What’s funny is a centri actually makes more average power than a whipple from what I’ve seen. Pd blowers will quickly supply air, but eat from the gains as rpm rises. The drag on a voodoo mill is strong enough that pullied for only 8psi, there is just barely enough airflow to fully fill the chambers at 8krpm. The turbo system had done this by 3500-4000. That’s exactly why I’ve stuck to my opinion for the last of what I call the low range, all of the mid and high range. The charting and physics verify that.

That said, it sure is fun behind the wheel. The whipple gt350 I drove was one of the funnest street cars I’ve driven. Exceptional, almost perfect. I think a whipple gt350r would be incredibly fun.

Too much torque is useless. When I did my latest build, I put rpm and linearity at the front of my mind and torque Wasn’t even stressed. Still ended up with 700wtq at 4500rpm with 800whp at 7000.