Kevin,
With the same mindset why stop at say 15 MPG, why not compare that 15 to what a moped could get? The only difference is 8/15 or 15/30+ of the moped. In reality they are the same argument but with different thresholds of pain I guess.

I hear what you are saying and have just made changes from 4 miles per gallon to maybe 8 MPG now. My main drive was to be able to run pump gas and not the race gas. I had to haul with me. Sure cost was a consideration but availability was more of the issue. Thank goodness I could not get 110 octane at a 7/11 to make me decide or prove your point. LMAO

thanks for all the replys.. mpg is not oo much of an issue right now, i just dont want to regret not getting enoug hp but also having too much that i cant enjoy driving it.

as for headers and side pipes. are the factory units that bad on th hp #s where can someone get an after market set of headers and pipes from?

again thanks for all the replys and for your time in posting

take care

Maxum,
Where are you located?


Kevin,
If I make a conscious effort, I can get about 10 mpg around town.
If no effort is made, 6-7 mpg around town.

When I was getting 6 mpg with my old BIG horse power motor the problem was: Having to stop every 75 miles for gas! Man that got old, not to mention with the high compression needing to run 'race gas', which you could never find on a trip! My new motor gets 11 to 12 mpg and is much more streetable (pump gas), the additional cruising range is a real plus and makes a solid case for:
1. 42 gallon tank if you don't care what your mpg is. :D
2. MPG consideration when you spec the motor.

Now it's your call which way to go. :LOL:

I've got one of the new 427 Roush / Shelby FE alumn. 511 block. 600hp and 625 torque. A real monster when you want it. As they say priceless !!!! Check out my gallery. Gets about 8 to 10 mpg and will run on 92 octane but loves the good stuff (100 octane race fuel ) when I can get my hands on it.

Great engine spoooky. I could handle 8-10 mpg.
Your gauges look great at night.

Spooky,
Better watch out, you might get taken to the dyno!!
I was getting 16 to 18 mpg on the freeway with my Holley 1000 cfm and the larger diameter tires ( no messing around). Freeway speeds would be around 2200 rpms. I haven't checked it since I changed to the BG 850 and the smaller diameter tires.
Scott

Spooky,
Welcome to the group. I only have about 200 miles on my Roush 511 8 stack so far. I did one tankfull of 110 octane(that motor loves it) and 1 tankful of 93 octane. It gets better mileage obviously on the 93 wihtout too much of a loss of power but that motor absolutely sings with 110 octane. Did Anthem build your car or did you do it yourself? I have went through a couple of tankfuls so far and I can tell you that on the freeway in 5th gear I am about 2000 rpms(loafing) and it was about 15mpg. driving it the way I do to enjoy that 511 and it was 7-10 but I will take that any day to get the grin on my face that the motor causes!!:D

I happen to agree with most of what I've read on these posts. When referring to HP, Carroll has said, "enough is never enough". That's why we decided to do something that has never been done before. Our company, in partnership with Sean Hyland Motorsport in Woodstock, Ontario, is installing a 5.4 L modular GT500, aluminum block 1,000 HP engine in a CSX 4000 Cobra. Yes, that's right, 1,000 HP running on E85 pump gas, mated with a TKO600. You can see it this November at the Sean Hyland Motorsport booth at SEMA. (You read it here first.) I'm a Cobra dealer in the US. Over the last year, we've been using Shelby aluminum FE blocks and SHM's services with great success. Sean builds an awesome motor using the best components (T&D rocker assemblies, JE pistons, Tilton starters, etc.) Our collective experience tells us that if you do it right the first time, using the best possible components, the quality of your phone conversations with customers improves greatly. Instead of receiving calls with complaints about fluid leaks or funny noises, you get to hear how much fun they are having with their Shelby, SPF MK III, GT40 or Datona Coupe. Frankly, those are the calls we live for. I also agree a TKO600 is a good choice for a Cobra. .82 is my preferred 5th gear OD ratio for all around performance. A .64 ratio is good for fuel economy, but at 70 mph and 2,000 RPM, torque is pretty limited, even with a big block. For the record, I've been a Shelby Cobra dealer for years, from the previous regime to the current. It's been a wild ride. My office chair has seat belts.

HP? Enough is never enough . . .
 

Sorry . . . my computer froze. I posted this twice by accident.

:eek::eek::eek::eek::eek::eek::eek::eek:

What a BEAST!!!

Power
 

Without making this sound like a "my penis is bigger" post, all I have to say is that in my 3000lb West Coast Cobra running Kumho V700 335's on the rear, 600rwhp is the most I can connect without getting sideways on the freeway starting at a 60mph roll. It's a big block/supercharger/efi combo, and the supercharger was pulled at an 80/30 ratio when I first tried to drive it. I've now pullyed it back to 80/40 and this traction problem still exists, so I run 19deg total advance to keep the power to a point where I can drive the car without breaking traction every time I feel the urge to step on the gas. Add 2deg of spark up top, and the tires do a pro-stock burnout starting at freeway speeds. So, if you have a lighter car and narrower tires with a less-sticky composition, you may want to give this a little thought unless you specifically are constructing a burnout/drifting machine. Yeah, it's cool to have a car that can do this sort of thing, but as far as I'm concerned, it lost its novelty and never improved my driving because I'm so nerve wracked to drive the thing that I find myself in "survival mode" instead of "drive mode" behind the wheel.

Byron

Spooky..

Tim, How have you been? It's been awhile since we heard from you.

As far as HP goes.... I have a small 302 putting 267 at the rear wheels, I have the dyno sheet someplace. I love it. I am not trying to impress anyone with big numbers. I just drive, drive and drive.

There have been times where I have said I want more, but then rethink it over and say why? I don't need it. The car scoots nicely and is fast enough for me. I think it really depends on what you do with the car. For me cruisin is the thing. I don't street race or take it on the track.

My 2 cents.

Mike

I believe you Bryon. My Cobra has "only" 345 hp, but is very flat torque curve and it just hooks up and goes in second and up. I love it and feel very secure and not afraid to push it any time, well almost. I took it to autocross school and what a blast. With more HP it would have been more of a challenge to keep it on course.

Lee

Missing posts...
 

There are 2 or 3 posts missing from this thread that were there last night. Anyone else notice that?

Please disregard, I confused this thread with another one.

Byron's post ought to have a sticky on it that anyone who is building their first Cobra engine is required to read, and, for anyone that asks "Why are there so many 500+HP Cobras for sale on Cobra Country with less than 1000 miles on them.":cool:

Heh heh - it may well be the "survival factor" is over-riding the "bragging
rights factor" for THOSE individuals who have decided to sell with "barely
broken in" mileage on their Cobras. Nothing wrong with that but it can be
an expensive decision.

Tunable Power...
 

The only saving grace of my "eyes bigger than stomach" combo is that the power is tunable. NA, the engine will probably make close to 450-500rwhp. With timing retard, probably 400-450. So, with pulley changes and changes to the blow-off valve I can tune it to that level if so desired. Had I built a 1000hp NA engine, my options would have been far more limited.

One mistake I did make was cam. It's too big to cruise nicely under 2400rpm, and I find myself in 4th gear to stay there when I have a double overdrive 6spd available...so it's a bit of a waste. I'll be changing from a 242/256@.050 duration cam with .680 lift to something with about 10deg less duration and .080" less lift. It'll lose some lope and make peak power sooner (and less power) but will allow me to cruise under 2400rpm smoothly. I'll then tailor the power with boost once again until I'm at that traction limit. I like to be able to come out of corner exit, get it straight, mat it...and have it stick.

So, if you want something that has a real wide span of tunable power ranges without having to dig into the mill too deeply, you might want to consider a power adder EFI combo. You can do a lot with the keyboard instead of a wrench, and your option to change power further with easy to access surface parts (like pulleys) makes life easier.

That said, this entire exercise taught me that I probably would have been just as happy with the way the car drives had I put a 514 crate motor in it...and I would have been driving it 6+ years earlier. (I'm slow). One thing my car does have is additional wow factor when the hood is open. People just don't see that every day and for those that understand what they're looking at, it's a real conversation starter.

Byron

Hey Byron, just thought I would mention the cam in mine.

600 lift, 252/260 duration @ .050 112 lobe sep.
It's perfect for me on the hwy & street, as I live outside the city.
It likes to idle at 1,000 -1,100rpm.

Okay just my 2 pennies here but the Roush 427 R's cam is not (in my opinion ) as street friendly.
What are you planning on doing with the car? If it is a street cruiser I would suggest the 427SR/Tw it is very well mannered for the street and the power comes on heavy at 3000 rpm!:3DSMILE:

I get 10-14 MPG with mine with the tko 600 5speed, if you find you want more HP later you can always upgrade to the injection set up for better throttle responce and roughly 40 more HP.

Marc:cool: