750+ cubic inches in a Cobra?

[Lightning]

I'm dreaming up a Cobra to assemble one of these days, and I've always wanted a 'mountain motor' with 750+ cubic inches (same size as the IHRA pro-stockers). With the kits available now, is it possible to fit an aluminum mountain motor into a Cobra chassis, with a manual tranny? All I want is a simple, four barrel carbed, non-nitroused, streetable engine with lots of cubes. I don't plan on racing it; I just love the feel and sound of a lopey, rumbling big block in a lightweight chassis. I'm sure you guys know what I'm talking about! Has anyone done something like this? Who's kit was used? I'm not looking for practicality or gas mileage, I'm looking for the rawest form of big block V8 horsepower in a lightweight street legal vehicle.

[427sharpe]

Lots of strokers in here! One of the nice things about Cobras is that you can put almost any motor/trans in one. A lot of mfg's make kits for a variety of motors. The problem with the mountain motors is that there is very little clearance in the hoodline. To use a motor like this, say a Kaase, you'd have to run a pretty big hood scoop...it has been done and the results vary from car to car. Take a look thru the galleries, and you can see quite a few variations to give you an idea of what I mean. Good luck!

[PatBuckley]

I love that idea!

The only problem - to me - is keeping it an FE.....but a 700+ cube engine in a Cobra is too cool.

As I have said before to friends, my idea of an engine is one that allows you to idle past someone with the tires smoking!!!

What are you thinking - 9 to 1 CR, 5500 redline etc?

[Lightning]

Originally posted by PatBuckley


I love that idea!

The only problem - to me - is keeping it an FE.....but a 700+ cube engine in a Cobra is too cool.

As I have said before to friends, my idea of an engine is one that allows you to idle past someone with the tires smoking!!!

What are you thinking - 9 to 1 CR, 5500 redline etc?

I've always loved big cube engines...I want to build up a nice, simple, powerful Cobra, just like the way they were intended, except put the motor on steroids! I'd like to run the motor on premium pump gas, so 9:1 CR should be okay, redline maybe to 6000 rpm (gotta find a builder who will blueprint and balance a mountain motor), 4 barrel Dominator carb (Holley/Demon), roller cam, MSD ignition, electric fuel pump...I guess the heads, intake and cam specs will have to be matched by the engine builder, but I want a stout engine (1 hp per cubic inch or more would be ideal) that will be reliable and streetable. Big long tube headers (with crossover tube) will help give it that pro-stock exhaust lope. I guess the biggest radiator (with corresponding mega-fans) will be a must.

I like the engine bay to be really neat and clean, with not much wiring or accessories in the way, so no power steering or heater hoses. Power brakes would be nice, but a high lift cam with lots of overlap/duration may not make much vacuum. A good strong manual tranny (maybe a T-56?) would be necessary, as well as a good rear-end. Gosh, I wish I could start building it right now!

Since I ride fast bikes, I want a car that can simulate the power rush of a big-bore motorcycle...this recipe will essentially be a four wheel equivalent of today's superbikes!

[750hp]

750 cubes = BIG $$$ Tall deck block, raised cam tunnel, belt drive etc.

600 cubes will still give you that big cube rumble for LOTS less money. Using an A460 block and a Scat 4.5" crank, you can get in the 600s without going for the radical custom parts.

BTW, any little old small block with the right blower can keep up with a superbike in a straight line

[cobrashoch]

I don't like the way that mountain motors have to be built for Cobra applications. A better way to build a Cobra is to build a normal hot rod type motor, drop the compression and add a huffer. The net results of mountain motors generally make such cars untractable for the street. What kind of car are you going to put behind it? I can't even tell you the crazy stuff I've had to do my car to get it to handle the power that I develop let alone a mountain motor. Most aftermarket Cobras have a chassis that really can only handle about 600 ft. lbs. of torque. You will find that most kits out there are designed with a certain parts orthodoxy that peak at about the 600 hp point. After that you kinda start getting into issues. These issues drive the costs up, not to mention drive up the weight. Don't get me wrong though, it can be done, but bring money, bring lots of money. It's not as simple as putting a parts list together and building a car. If you are like me and enjoy the mechanical challenge above all else I say go for it. But if you are more of street driver type I'd say one of the normal Cobra's kits when completed is MUCH more than you will ever expect out of them. And that's with a modest 400+ motor. The normal sage advice of building one of these guys is to build the car first then add a bigger motor later. I'd say that 80% of the time the orginal motor is more than enough though and that bigger motor never gets built. Been there, done that.
cobrashock

[Jack21]

If I were going to build another Cobra that would be the ultimate showstopper, I'd use a WWII vintage Allison or Rolls Royce aircraft engine. These things packed 1,800 cubic inches and made around 2,000 horsepower. They're 50 years old, but you can find them if you shop around. They make great tractor pull engines so there are trans adaptors, motor mounts, headers, and stuff for them.

Would love to drive something like this to DVSF and upstage DV's V10 Cobra.

I'd use the original valve covers as patterns to have a custom set made that had "COBRA" engraved on them.

Another show stopper I've been thinking about is a jet turbine engine out of a Tomcat or something. Nothing exotic about the fuel, it uses kerosene. I know it can be done because you see these things in Kenworth tractors running in jet funnys. I love watching them do burner pops before running the quarter. These things weigh about 18,000 pounds and are running 6's. In a 2300 pound Cobra, it should run 2's or 3's easily.

But mostly, I want to see the look on the guys face chasing me in his Viper or Vette when I give it a little throttle and scorch all the paint off his car, or do a few burner pops waiting for a light to change.

Hey, don't flame me over this. I'm not building it yet, just checking out the engine availability.

[Randall Thomas]

I am in a project of just those biblical proportions right now. Other than the rationalization issues and sanity considerations not to mention car strength capabilities, let's just look at the physical fittment for the time being...

I did this work on a Superformance due to the proven strength this car has shown in absorbing 700-800 and even 1000 hp along with huge doses of torque, in the past. This work was centered around a 460 Ford based block design since this is where the huge strokers are coming from, and as inexpensively and easy to to as they get.

To fit that many cubes into a block, you have to go big. The block is bigger, taller, heavier, stronger... not to mention more expensive. But when you're talking something important like your hobby, then money is no object. Just keep repeating that to yourself.

In order to get a longer crank in there, the deck needs rise like a skyscraper. As the deck goes up in height, the valve cover to hood clearance depreciates. I was able to go up no more than 2 more inches taller on the block deck in a Superformance before the heads and valve covers became an issue. Carb clearance was already an issue, but the deck did not affect it that much. Super low profile covers are needed and some really expensive "compact" valve train components were necessary. While I suppose a carb "could" stick out of the hood, I'm not so sure the valve covers should be as well.

Unfortunately, as the deck rises, it also widens at the same time. That became an issue with the Superformance steering column, which can be relocated to accomodate the larger chunk of alloy block and heads now in the way. The few folks with the 427 Cammer motors fall into a similar category.

The heads you "should" put on that engine, whcih are Arias, will not fit under the hood... so a comprimise in the best SCJ Alloy head out there will have to do. But boy, would those Arias hemi heads look good stickin out of the slots you'd have to cut into the fenders and hood for clearance! Then people would be asking you at the stop sign, "u got wun a dem himi's under yer hood?"

I've heard of 910" engines in a 460 base block, but that's about when the Tractor pull and drag orgnaizations clipped them at 650"... a mere 650 inches!!!

Anyway, with the physical limitations of the engine compartment and head clearance restrictions, you may be able to squeeze a 795" engine in under the hood if you use a dry sump oil system, thus reducing the lower pan depth allowing the engine to sit a little lower in the frame to provide more cubic inch clearance up above.

Keeping it cheap and compact with a stock iron block (67-69-ish in vintage) sleeved, most of those can be overbored about .190" and with the same stock deck and a 4.5" stroke crank will yield you an inexpensive 585".

Next step is a Ford A460 iron block overbored .265" and a 4.5 crank giving you 605" and that's still with a stock deck height.

Then you can use the Aries A96 alloy block with a 2" taller deck, overbored .265" with a 5.5" crank to give you 738". You could get 815" from this block, but the crank arm would be getting into mythical proportions. Of course the costs would be astronomical, but hey! It's for your CAR, and hobbies have no budget, right? ... at least mine never seem to end up like they ever do.

Good luck and hope this gave some insight on the options. Just remember, to get a single motor to have nearly TWICE the cubic inches than a single stock big blocks, will certainly cost FOUR times the amount... if not more, so maybe somehere in between is where you'd want to shoot.

/Randall

[BB427]

A mild 700 ci. mountain motor on pump gas

The only thing is it would look goofy . Kind of like the matchbox cars where the motor is a foot above the roof.

Not too cool when a 302 FI FFR blows by while you sit n spin. Sounds less like a Cobra and more like a centerfold for a JC Whitney Christmas catalog .

[SFfiredog]

Lightning,
Here is your recipe.
C&C Motorsports aluminum block 11.7" deck height
4.625" bore
5.25" Billet crankshaft
7.25" Oliver billet rods
Ford Racing or TFS A-460 or if you really want cool, C&C Motorsports Boss Hemi heads
705 ci
Jesel valvetrain
mild roller cam
272 degrees duration at .050" lift .780"lift 114 lobe centers
(that's mild for an engine that big!)
Ford A-460 or C&C cast single Dominator intake with spacers for the increased deck height
10.0 to 1 compression
Should make an easy 800 to 825 hp at 6200 rpm on pump gas
You get the money together and I'll build it for ya

--Mike

[Bill E]

Mickey Tomson 1130HP this will be in a car next mouth

[cobrashoch]

Randall- I agree with your semi-sarcastic realism. The only point I differ with is the point that a Superformance Cobra can take such motors. I guess it boils down to what our mutial definition of "can take it" means. In my NHRA world a factored 350 horsepower 2500 lb car runs in the mid to high 10's all day long with control. Just because a 800 horse motor can be shoe horned into a car and it doesn't shake itself apart doesn't mean that a car can "take" the power. In that respect a Superformance fairs no better than any other Cobra I've been in or worked on. And trust me, I've been in a BUNCH of big block Cobra cars.
Bill, I'd love to see that thing in a 90 inch wheel base car. Just the thing I was talking about above.
cobrashock

[Lightning]

Wow, getting mixed messages here! And some good advice too. Remember, I'm still dreaming about what to put together...this is the only time when you can let your imagination run wild, and not cost you too much

I don't see anything wrong with building up a normally aspirated big cube engine that runs on pump gas...whatever happened to 'there's no replacement for displacement'? Gen III Vipers run 505 cubes (not too big, but respectable) on pump gas, and I don't see any of them complaining? Remember I'm not gonna be racing and competing with this car...I just like the look, feel and sound of a big block V8, that's streetable and reliable (hence a big engine that's mildly modded, instead of a smaller engine that's pushed to it's limits).

When I'm at the point of actually starting to buy the parts and talking to an engine builder, that's when the 'practicality' and common sense issues come to play, and there's a good chance that I'll be using something less radical than what I mentioned in my first post. Of course, I'll be asking advice from seasoned Cobra owners who've been there/done that, to be sure I'm not going 'off the deep end'. If I did use a mountain motor, I'd probably try to use the lowest profile intake (non-tunnel ram) and valve covers possible, with dry sump...a 'small' hood scoop would be tolerable. Definitely no room for blowers.

750hp,
Just wait til you strap a turbo on a 1300cc Hayabusa superbike...last month one went 249 mph in the standing mile at the Maxton Mile...and it' completely street legal...how's that for straight line performance!

[A Snake]

Lightning

That's why it's called "Bench Racing".

Al

[cobrashoch]

I'm the original big cubed god. That's where blowers come in. But you are talking about a Cobra or a hot rod? There is a differance you know. Yes I know a Cobra can be hot rodded, that's the war I'm in. EX.-What kind of drivetrain ya tinkin about?
cobrashock

[BB427]

I am with you on the CUBES!! Got rid of a 90 Ford Probe S/C car with a 572ci. alky injected BB. If you want big power you need a big arm. I just think it is for show in a cobra because you sure can't "use" that torque the ways these cars are built. I have had 1072HP (single 4 bbl never put the injection on the dyno) and it is awesome, however,in a cobra ??

But I do love to "bench race" This is the time of year for it.

Have fun!!
Brent

[Lightning]

Originally posted by cobrashoch


I'm the original big cubed god. That's where blowers come in. But you are talking about a Cobra or a hot rod? There is a differance you know. Yes I know a Cobra can be hot rodded, that's the war I'm in. EX.-What kind of drivetrain ya tinkin about?
cobrashock

Well, I'm trying to 'hot rod' a Cobra, so I guess it's a little bit of both. I guess the best of both worlds would be pro-stock power thats streetable and reliable, in a Cobra chassis that handles like a track car and launches like a drag car too. Now wouldn't that be nice! I guess I need to keep dreaming (and saving $$$)...

[cobrashoch]

Lightning - Interesting trip you are about to embark on. Good luck on you quest for automotive perfection.
cobrashock