Those who have gone Twin Turbo...


TORQJNKY

GT Owner
Apr 18, 2013
76
Chesapeake VA
Over the last year or so, I've been contemplating making the switch from Whipple over to Twin Turbo. IMO, a 05-06 TTGT is the pinnacle when talking about the baddest American made ICON's of all time. Ask Mark at M2K :cool:. I've thought about just upgrading the Whipple to a 4.5L with supporting fuel mods, and calling it a day. But the sound, efficiency, power and usability (boost adjustable without pulley swap) of twin turbo's, oh did I say badassary, has me moving down that path. Some will argue for supercharger, some will argue for compound boost and others are like me. I know many have used Hefner, M2K, Dallas Performance, Fischer Motorsports etc.. all of which build sick cars. So I'm here to leverage that experience and get some good info and perspective to help me make the best decision.

What I'm starting with: 05 GT, Fully built Accufab Racing engine, Whipple Supercharger.
Goals: 1200WHP
Use: Weekend warrior, 1/2 and mile racing events (I may ever only run a couple of 1/2 events and 1 Texas Mile)
Tunes: Low Boost 93, Pump E85, Max Effort C85 or other fuel

My thoughts on a kit:
* Precision Turbo 64/66 GEN II BB turbo kit to include Twin Precision Wastegates and Twin TiAl Blow off valves
* Custom billet intake (Thinking Shelby Mike Racing, but I'd like to stay with my Accufab TB, but not sure this intake supports and oval) Needs to look good too :)
* Spec or McLeod Twin Disc Clutch (Suggestions?)
* Fuel System (really where I have the most questions): Injector Dynamics Injectors (Size ?), Fuel Sump (pump and best kit option?), do I need to go return?
* Engine Management: I understand some have made 1100whp or so on the stock ECU. I don't know if MoTec is in my budget right now. Is it a good idea to wait until it is in my budget or can I reliably reach my goal with the stock ECU and upgrade to MoTec later?
* What other things so I need to consider?

I essentially could just send it off to one of the talented shops previously mentioned above, but I live in Virginia and that adds about $6K to the budget in shipping, that could potentially go towards a MoTec kit. I'll be using a shop local to me called Horsepower Solutions. Josh and his team have built some super badass turbo cars and race them weekend after weekend. Thanks for any insight you can provide.
 

mmlcobra

GT Owner
May 25, 2013
1,223
All I can tell you is go to Heffner.
Jason is meticulous.
The fabrication skills there are unique.
The shop is cleaner then most operating rooms that I have lived in!
Have had my TT Heffner 2005 GT for many years.
He ABSOLUTELY stands behind his work.
Other then Chuck Tator (the Viper Wizard), I have never met a more honest guy.
Best of luck with your quest.
Mark
 

GT@50

GT Owner
Mark II Lifetime
Dec 14, 2019
941
Issaquah
Don't forget the trans. I think there are some billet pieces available now that would be a worthy investment. A lot less expensive than replacing a scattered trans.
1200HP and budget is an oxymoron.
The cheapest way to get there, and live, is most probable from somebody that has done it before.
Do it once, do it right=spend the $$$$ now.
And post pics
 
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JOETWINT

FORD GT OWNER
Mark IV Lifetime
Jan 22, 2008
438
Brooklyn N.Y.
Slippery slope but I would say if you are going to do it let Heffner do it all or dont do it.I have seen that mistake made so many times over the years where people say I can do it cheaper at this shop rather than going to Heffner for my Ford GT or going to Underground for my Lambo etc.It almost always works out to being double the cost or they end up selling the car.

Oh,and if it going to be a weekend warrior stay away from the corn and tune the car on C16 or 109 or pump.Everybody loves E85 because it is cheap but in a car that is used once a week it attracts water and will wind up ruining your fuel system.Plus it makes the fuel system more complicated since u will need to build a fuel system for around 1800 whp if u were running C16(bigger or more pumps ,bigger injectors, larger fuel line, etc.
 
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Iconic GT

GT Owner
Mark II Lifetime
Dec 30, 2017
708
New Braunfels, Texas
Use: Weekend warrior, 1/2 and mile racing events (I may ever only run a couple of 1/2 events and 1 Texas Mile)


I essentially could just send it off to one of the talented shops previously mentioned above, but I live in Virginia and that adds about $6K to the budget in shipping,

Will you be trailing to events? Do you already have a trailer? If not invest in a trailer and get it in the hands of the best like Hefner or M2K and get yourself something that will accomplish your goals with these least frustration. Your entering a world where Benjamin’s have wings And or legs.... Point em the right direction!

Best of luck and be sure to keep us all posted!!!
 
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nota4re

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 15, 2006
4,281
If you search this forum, you will discover that I have historically offered quite a few opinions regarding the Supercharger vs. TT debate. Having installed 7 of Jason's TT kits and having a hand in improving that set-up to build boost almost 1000 rpm's sooner, I think it is an outstanding upgrade. There are many advocates of the big SC, instantaneously available boost, etc. but to all of these I just say drive a well turned TT and you'll be a convert.

That said, I would strongly encourage you to set you HP goals to 1000 RWHP. ALL of the TT's that we built attained 1000 RWHP and did so with virtually stock fuel system and ECU. Add TurboSmart's in-dash boost gauge/controller in place of your OEM boost gauge and you have your in-cockpit boost control at your fingertips. The car retains ALL of its everyday driveability (save for a noticeably heavier clutch pedal), but can easily be transformed into a beast. However, keep in mind that adjustments to boost levels will almost always require higher octane fuel so you need to exercise some restraint.

I would say that almost every owner on this forum could have this upgrade performed and it would not to any significant degree change the amount of time they need to invest in driving, enjoying, and maintaining their GT. The most significant difference as I mentioned previously would be learning to live with a heavier clutch.

All of that said, IMHO, the step between 1000 RWHP and 1200 RWHP is a substantial step in cost, OEM driveability, and maintainability. Although the clutch would likely be the same (we prefer the SPEC clutch), you would likely have to begin thinking about transaxle upgrades which can be expensive. The biggest changes will be in having to change the fuel system - larger pumps, custom sump, larger injectors, and potentially new engine management. These steps will add considerable expense and will leave you in a perpetual, intimate, love-fest with your GT. For me, it crosses the line between an everyday park and drive car, to a specialized full fledged race car with all of the attention (and $) that a race car will require. Several owners have pursued this path. They are highly skilled car enthusiasts and this is their passion. My hat is off to them, and to you, if you elect to pursue this latter course. Just realize that it is a substantial step.

It all depends on what you want and how much $ AND TIME investment you want to make in the car. You mentioned 1/2 mile venues and such, just keep in mind that someone will ALWAYS be faster. You can bring a 600HP, 900HP, or 1200HP car.... someone will always faster.
 
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B.M.F.

GT Owner
Mark II Lifetime
Jan 29, 2009
1,810
Minnesota
I offer probably the best surge tank/fuel system set up for a return style system that allows you to not touch the oem tank or pumps. Anything over 1000whp will require a fuel system. Esp if planning on using e85.. It will support 1500+whp on e85.

I also just about have the new 2.65 tvs supercharger kit done for the 05-06 GT and it will make around 900-925whp on a stock untouched motor at 25-26lbs of boost and will support 1250whp on a built motor. Much smaller blower than a 4.0 or 4.5 whipple, Less stress on the crank and it's more efficient than the old design 4.0 rotor pack.
 

MarkH

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
May 19, 2007
542
Katy, Texas
At the end of the day, there is one shop that has done more MoTec stuff for the GT along with twin turbos. M2K has developed a “plug n play” system for the GT using the MoTec and if you want to make the power you mentioned why try and reinvent the mouse trap.. call Kevin at the shop and go with a proven product... yes I am bias but I have spent a lot of money trying a lot of other different applications, so why not use some of the expertise Kevin has over the years. Tried to take a pic of a MoTec he is wrapping up on a Hefner build.

Mark H.
 

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