Turbocharging a Superformance Big Block???

[fordracer]

Has anyone here successfully put twin turbos on a 460/514 in a Superformance roadster???? If it's been done what kind of body/underhood modifications were needed???

[ffindling]

It can be done, but not easily. Probably the biggest challenge in such an
installation will be the intercooler setup. It has to go in front of the radiator
and there isn't much room there. Since you want twin turbos, the intercooler
will have to be a two-section unit with separate intake/discharge connections.
The intercooler will probably have to be custom built for your application,
a number of shops can do this, but it will be pretty expensive. A larger water
radiator will probably be necessary as well as it is going to be deprived some
cold air flow going into with intercooler sitting in front of it and fitting a larger
radiator will be challenging as well with the air plumbing go to and from the
intercooler taking up space where the radiator resides. Custom headers will
be needed to route the exhaust gases into the turbos as well as some custom
plumbing to route the turbo discharge to the sidepipes. Assuming you will be
using EFI, you will need to make sure whatever ECU you decide on supports
a twin turbo installation with electronic wastegate control on each side.
I believe the Electromotive TEC3r can do this but there are probably others
that can as well.

....Fred

[ByronRACE]

The turbos need to be above the oil level unless you're going to rely on some kind of external scavange pump to lift the oil back into the pan.

If you're turbocharging a 385 series, you obviously want more than 800rwhp, so you'll need a pair of turbos that are quite large in size...like a pair of T60's or something similar.

Take a look at a 385 based SPF. Those turbos all by themselves aren't going in the engine compartment; let alone the plumbing. So, they'd have to go somewhere else...like probably up in the nose behind the headlights or behind the tires in the front fenders somewhere. You'd have a real problem on the drivers side with steering, brakes, etc... I think you're going to have a major packaging problem. And, we havn't begun to talk about the plumbing/intercooler.

If you're willing to stick them through the hood and make a "log" style exhaust manifold, you could simplify the plumbing a lot and make it happen easier...but it won't be too pretty; unless that's the look you're going for.

A single turbo low and in the front would be an easier solution. Or a supercharger with a mount like mine. The same basic configuration could be accomplished with a single turbo and some front-swept exhaust that comes to a shared collector right at the turbo.

It'll tend to kill your exhaust note...turbos quiet an engine a lot. Be aware of that up front.

And, with a turbo, you'll need an intercooler. Turbos generally use smaller impellers spinning at higher rpms and create far more intake heat at a given boost level. Even at 8psi or so, I think you'll see 200+ deg intake temps without an intercooler; that won't work well.

Personally, after having gone the power-adder big-block route in a Cobra, I'd advise you against it. (A) It's ludicrous and largely unusable. (B) You can build a little 545 stroker with some A460 heads and make over 750hp to the tires on pump gas...how much power do you want?

My tires are on fire at freeway speeds at right around the 500hp mark (per my datalogger)...beyond that, I don't see the point except for the cool factor of having that capability. It was/is cool; granted; but the wow factor wears off shortly after you've done that a few times.

My stuff is at http://www.racesystems.com/cobra if you want to look at it for ideas.

Oh, and I should mention...my car is an old West Coast Cobra. I believe the engine bay is longer than SPF by about 4-6", and there's a lot more room in the fender wells.

[ffindling]

Originally Posted by ByronRACE

And, with a turbo, you'll need an intercooler. Turbos generally use smaller impellers spinning at higher rpms and create far more intake heat at a given boost level. Even at 8psi or so, I think you'll see 200+ deg intake temps without an intercooler; that won't work well.

I agree 100% there, to use any meaningful boost pressures, a pretty stout
intercooler system will be required and packaging that in the confines of an
SPF or just about any other replica is going to be extremely difficult and expensive.

....Fred

[mike knight]

my experience with installing a turbo in an spf may be of interest. i have a 351 windsor with a 93mm intercooled turbo. i actually bought 2 56 mm turbos as that was my intent. we could not lay up a plumbing system for the intercooler and turbos in the engine compartment. we had made arrangements with the supplier to return the turbos if we couldn't succeed. there simply wasn't enough space for all of that 3" piping and intercoolers. i even went to an electric radiator mount water pump. after a considerable amount of work we decided to go with the single turbo.
i have also experienced cooling issues. my car in traffic on a hot summer day wants to run over 105 c, about 220 f, and would probably continue to climb slowly. on the highway it runs perfect at about 180f. more work to be done with the cooling system over the winter. you can see a couple of pics of my installation in my gallery. i know you are asking about turbo installs for a 385. i can only imagine you might have the same issues as i with my small block, only compounded by the size of your motor and exhaust system.
i will say that performance with the turbo at about 30 lbs of boost is insane. i am driving on the street with about 7 lbs of boost and acceleration is very quick. in third at 60 mph if you stand on it the rear 295's break loose. at 140mph in 6th it pulls hard. turbo whine is very pronounced. mustang dyno with 7 lbs of boost equals 596 rwhp 4800 rpm and 613 ft lbs at 4250 rpm.
incidentally what you see in my pics was expensive. fyi

[fordracer]

In all honesty I do not have a Cobra yet. Long story short I have wanted a Cobra for the last 29 years.

Now that I have some money I am trying to decide what I want. Fortunately or unfortunately I have had many years to build a perceived notion of how a Cobra should run. As I've gotten older my tolerance for all out race cars on the street has dropped.

This leaves me with a choice of buying a used ERA, and its possible inherent problems. A new Superformance. A new Dodge Viper or a new Z06. Again to be brutally honest, a Viper and Z06 with factory 500hp,a warranty, and everyday reliability sure looks good. Add to this the relatively cheap ways to gain even more power from the Dodge or Chevy is an even stronger argument.

But, compared to a Cobra there are Vipers and Corvettes on every corner. I could buy a used ERA, sell off the FE that it came with to fund a new motor of my liking or, buy a Superformance and also have a motor built to my liking.

I picked twin turbo because I was only thinking of the side pipes. If a single turbo is easier to package then I will do it. I don't want a centrifugal supercharger because I like the explosive acceleration a well set up turbo can give. I was also thinking of using the turbos as my mufflers. I have read too many threads on how restrictive the exhaust is on these cars. It doesn't turn me on to build a 500+ hp motor only to have it choked by something as silly as a muffler.

Thanks for the responses

[ByronRACE]

If you do decide to go TT, I'd recommend finding a very vintage-incorrect car with lots of fender well room. One of the 96" wheel base cars would be easier as well; more room.

And, if you do go single turbo, there's no reason you couldn't do side pipes...you'd just split the exhaust. You wouldn't need mufflers.

Another idea I thought about on my car when I was considering TT's is to mount the turbos externally and low. Basically, you'd build headers that would terminate at a turbo flange in the typical location where the side pipe exits the body. Put a filter on the turbo, coat the hot side, polish the cold side, and build the side pipe such that it bolts right to the turbo. The reason I abandoned this is the difficulty in returning the oil to the pan, and the potential for damage from road debris. As far as cosmetics, I think it'd look incredible if done right...but very vintage incorrect, of course. You'd have to have an electric scavange pump for the oil return. I don't think this is a show stopper...just ads complication. The road debris issue would be an issue potentially...you'd have to inspect the filters frequently.

As far as rejecting the centrifugal supercharger approach due to it not having explosive acceleration...think through that one again. My supercharger is running an 80/30 cog with a blow-off valve set to 10psi that operates much like a turbo wastegate allowing me to limit boost. Judging by the boost curve I've seen at low RPM, it's going to easily hit 10psi before 3200rpm at WOT. I can't discover this on the street...already too sideways by 3 or 4 psi. As-is, the tires disconnect from the pavement in 3rd gear at a 30mph roll as soon as you reach approximately 1/3rd throttle and 3psi of boost with only a tiny 435 CI 385 series Ford in a 3000lb car. More power than you can possibly use, and the power comes on WAY too fast for control/comfort. In fact, after I get my dyno number I'll be turning DOWN the power significantly with a pulley change...it's too hard to drive as-is, even after changing the throttle to have a full 6" of pedal travel!

[Excaliber]

If you plan to dump the FE, ERA is not the car you want. Get something that isn't known for being as 'correct' to original specs and modify it to your taste. Something like an SPF or an FFR would be more suitable as they typically come with a wide variety of motors anyway.

[Anthony]

Originally Posted by fordracer

In all honesty I do not have a Cobra yet. Long story short I have wanted a Cobra for the last 29 years.

Now that I have some money I am trying to decide what I want. Fortunately or unfortunately I have had many years to build a perceived notion of how a Cobra should run. As I've gotten older my tolerance for all out race cars on the street has dropped.

This leaves me with a choice of buying a used ERA, and its possible inherent problems. A new Superformance. A new Dodge Viper or a new Z06. Again to be brutally honest, a Viper and Z06 with factory 500hp,a warranty, and everyday reliability sure looks good. Add to this the relatively cheap ways to gain even more power from the Dodge or Chevy is an even stronger argument.

But, compared to a Cobra there are Vipers and Corvettes on every corner. I could buy a used ERA, sell off the FE that it came with to fund a new motor of my liking or, buy a Superformance and also have a motor built to my liking.

I picked twin turbo because I was only thinking of the side pipes. If a single turbo is easier to package then I will do it. I don't want a centrifugal supercharger because I like the explosive acceleration a well set up turbo can give. I was also thinking of using the turbos as my mufflers. I have read too many threads on how restrictive the exhaust is on these cars. It doesn't turn me on to build a 500+ hp motor only to have it choked by something as silly as a muffler.

I would suggest for you to get a "standard" cobra as your first cobra, and if you want to build something exotic, then do later. However, it seems like you're not a diehard cobra enthusiast, and you may be let down by other aspects of owning a cobra, so why invest alot of time / money / frustration in your first cobra, when maybe you'd be happier in a vette/viper.

Finally, there are different sidepipes, some with very little restriction. There are many people who could advise you on this.

[ByronRACE]

Read the thread regarding Z06 vs Cobra.

Owning a Cobra is like owning a vintage war plane. It will require constant care, but has a cool-factor that can't be replaced by the Z06.

They can't be compared, so buy both. I wanna see someone do a twin turbo big block cobra.

[fordracer]

Originally Posted by Anthony

.... it seems like you're not a diehard cobra enthusiast, and you may be let down by other aspects of owning a cobra.

Odd that you know me well enough to make such a gross assumption. I have owned,built,and driven cars faster than 90% of the show cars on this board so telling me that I don't know the aspects of owning a car as mechanical as a Cobra is ludicrous.

If you had read my post I have wanted, nay, lusted after this car for 29 years. When friends were playing games I was helping my dad work on his '34 Ford Coupe or '60 Corvette. When friends were partying or playing sports, I was building small block Chevrolets. I am a professional ASE certified, L1 advanced automotive technician. I have been drag racing locally since 1992. I am more than qualified to own,drive,and maintain a Cobra, unlike the majority who "build" their cars with a checkbook.

I like Byronrace's idea of using a blowoff valve as a wastegate on a centrifugal. I looked at your pictures Byron, that Vortech is HUGE. Which one is that?? I could use a "Y" trim, pulley it for some hellacious blower RPM to build boost quick and then blow it off. Question Byron, are you using a blowoff valve or a true wastegate on the blower outlet???

[ByronRACE]

The blower is a Vortech V7-JT reverse-rotation. The mounts are custom. Electric water pump; meziere WP-337 I think.

I'm using a Vortech Mondo bypass valve. I built a little fixture that hooks up to shop air to allow you to set the cracking pressure to whatever you want. I played around with springs until I found what I needed. The mondo valve has an adjustment screw that gives you adjustment range on the spring preload. Basically, it's a crude relief valve.

A computer managed waste-gate would be superior. Mine will have some boost creep as pressure gets higher. I have plans to mitigate that if needed using a boost controller to modulate pressure to one side of the diaphram to control boost to the level I need. Much like a conventional boost controller, just optimized for this big bypass valve instead. In this mode, the internal spring will be very weak and both sides of the diaphram will be plumbed to manifold pressure. When the boost set point has been reached, you'll start venting one side of the bypass valve diaphram to atmosphere via a 3-way valve. The resulting differential pressure will cause the diaphram to move and the valve will open...venting off boost. You'll manage this closed-loop using pressure feedback like a conventional boost controller; and should be able to maintain flat boost at any pressure you like, or even define a boost curve...or control boost using some other input like vehicle speed, rpm, wheel slip...etc. This is stuff to play with later...my car has a PC for a dash; so I plan to do all kinds of experiments with such things.

The only disadvantage to the aggressively pulleyed centrifugal is that at all points above your blow-off pressure level, the intake air temp will be higher than it would be had you just pulleyed the blower to achieve that same pressure by a function of impeller RPM alone. That is, pulleying the blower to produce 20psi at 7500rpm then blowing it off to 5psi flat across the board is going to make a lot hotter air than if you would have pulleyed it less agressively. You have to compromise some...don't go too crazy on the drive ratio, and don't blow it off too early, and you're fine. Right now I'm pulleyed for approximately 14psi (that's about max for this combo I think...considering my head flow), and blowing off at 10. That shouldn't hurt much.

The nice part about the Vortech is the efficiency. That V7-JT is 78% efficient. Intake temps at 15psi on other comparable race engines with this blower I've datalogged show 160-180deg air at max pressure; and less (of course) at lower pressures. Low enough that you can avoid intercooling if you simply use a low compression design and tune it conservatively. I chose to build mine 7.88:1. It's running 20deg total now; at what should be around 11:1 AFR...no dyno time yet. If you see yourself doing extended WOT; you should intercool it. After having driven my car...I can tell you now that I'll NEVER be doing extended WOT in this car...just short bursts for grin factor. I've been to WOT once for a brief moment...in 3rd gear at about a 50mph roll. It just went "BLAAAT!", bounced off the limiter (set below 5K for now), and I thought something broke...because I didn't go anywhere. A quick check in the rear and it became quite evident that the tires WERE turning.....to grease in fact.

[decooney]

fordracer,
IMO - unless you are going to turn it into a full-on drag car/suspension setup and race it, why so much power in a 90" wheelbase / IRS based car on the street with street tires? If you've never driven a hi-powered 700+HP Cobra on the street before with an IRS, get ready for a ride or a wreck! A close friend let his other friend (7-time NHRA World Record holder) step into his 580HP Cobra and he didn't last 5 minutes before he put it through a few fences and almost killed himself. Bad ass drag racer almost lost his head, literally. He quickly found out first hand why Cobras can bite you.

Another buddy just finished a brand new SPF 542 stroker for a customer, at 700HP. He kept trying to hint to the customer it would not be what he thought it would be. Customer had to have the biggest/baddest; so he proceeded. We all just sort of laughed shaking our heads, sat back and waited for the phone call to come in. Sure enough, didn't take but a few weeks, now the customer is reportedly selling the car becuase its a bit too much and not that easy to drive without swapping ends. Seriously, my friend says at any speed the thing just fries the tires and can get out of control quickly. Its a normally aspirated 385 series / 542 crate motor. The customer now wishes he had a 351 in his car. Oh, by the way, an ERA with 550+HP gets to be pretty useless if you ask me. That's about the limit. I spent months building/testing stronger diferential/ traction system that helps but its still and IRS. If you go 385 series, the SPF would be a better car to try that in my opinion.

I say go Drive or be a passenger in a true 500+HP (90" wheelbase) Cobra and experience it first before you decide to build an overpowered out of control 385 series monster with turbos. Good Luck.