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600-650 reliable efficient hp??

12K views 57 replies 16 participants last post by  DHenderson 
#1 ·
I was planning on a 545 inch stroker and shooting for the moon for power and dropping it in a street driven Torino. However, I just had a moment of clarity and realized what overkill that is for what I would really wanna do with the car. What I really want is something that can provide factory levels of reliability and efficiency while making around 550RWHP through a t56 and a 9inch.

My end goal is a car I can drive cross country with only a lash check and an oil change while doing close to 20mpg.

I know I'm asking a lot but with the right heads, right cam and minimal cubes I think I can get damn close.

TL,DR; Think Z06 Corvette powered by a BBF
 
#3 · (Edited)
A Z06 Corvette does well over 20mpg with 427ci. I don't think its unreasonable to ask IF and HOW a small inch high efficiency BBF can achieve similar numbers. Nor do I think its unreasonable to try to build a BBF for efficiency with optimal power instead of just stroking and adding a giant cam.

I know 20mpg and 600hp is a lot to ask for but so is 1000hp with P51 heads and a factory block but people still push the envelope. So don't tell me get a mod motor and turbo, that's counter productive. When people ask for easy way to 800hp do you tell them to find a Teksid block, 4v heads and 20lbs of boost?



Btw I rather do a LSx swap than cut my car up for a mod motor.... Not opposed to going back to a Cleveland though
 
#5 · (Edited)
#9 · (Edited)
I've done a 600 HP 460 that was reported to get ~18mpg with a manual overdrive trans and a carb.

What you're talking about is probably somewhat close to that assuming a 15% drivetrain loss. Making it a 429 might help with MPG's, a custom solid flat tappet, alum heads, dual plane intake, overdrive manual trans, and you might get close. Fuel injection would definitely help.
 
#10 ·
Thanks Carl! I think I remember you posting about that combination before. Can you elaborate on it a little. Heads cam intake carb compression?

And I agree, a 429 could get there and EFI would likely be a piece of that puzzle
 
#11 ·
In that particular combination, we used Edelbrock heads with an Air Gap intake, a hyd flat tappet cam, and fairly aggressive compression. The goal wasn't to make a mileage master by any means, it just happened to do pretty well.
 
#12 ·
To me it seems that to achieve these kinds of goals max compression is a must which means tight quench areas and a carefully selected cam.

As far as heads go, would P51s be too big?
 
#18 · (Edited)
Based on personal experience with my 460" LTD I would say that a goal of 550 to 600 HP crank with a manual OD transmission, EFI and High compression / thermodynamic efficiency could easily net 18 MPG with careful tuning of both AF ratios at cruise and ignition timing.

I am getting 14+ mpg with 3.5 gears, 3000+ stall convertor and a carefully tuned HP 950 built by comp carbs for the application. Idle feed restricters and air bleeds are all tunable on the aforementioned carburetor.

Up until about 50 MPH I am cruising on the transfer slots in the carb and can easily tune the cruise A/F to a target of 14.5 to 1. Above that I am starting to pull from the main well / booster venturis and the AF ratio goes from the 14's to the high 12's low 13's A/F. This is simply a matter of the airflow needs of the engine at 2750 to 3000 rpm at highway speeds. I can lower the float level on the primary side to delay main well fuel flow however I compromise drive ability at that point. A larger engine would of course make good economy harder to attain with a carb given the additional air flow needs at cruising speeds.

If I were to use a self learning EFI system set to cruise at stoic / 14.7 to 1 with a manual OD and or a locking automatic like the E4OD I would certainly expect to be near 18 MPG with a reasonable foot.

I am running 11 to 1 static c/r, 9.3 to 1 DCR, 220+ psi cranking with .039" quench distance with the DUAL QUENCH SCJ-A castings. I mention these heads because I feel that the minimal timing requirements of these castings plus the dual quench pads offer better octane tolerance vs the other std valve location offerings. at 460 inches I do not feel that the port cross section is too large given the amount of torque these castings make even at lower rpm windows.

I dont know if the new AFR offerings have a revised chamber and valve locations with dual quench pads...

I run 30 degrees total timing in by 2600 rpm and add 20 degrees vacuum advance in conjunction with the leaner cruise A/F's while on the transfer slots...

I think carl is on the right track as is backed up by my personal experiences.

I am making close to 550 crank HP with the 3 pattern roller cam and larger carb so I again agree that the MPG criteria is plausible...

I have contemplated the new FAST wide band EFI for exactly this reason.

One last consideration here is abundant airflow with minimal cross section at modest valve lifts paired with careful camshaft design. keep duration minimal for the power expected.

I would have some doubts about a 650 Hp combination NA making the grade due to the long duration cam needed however if Static c/r is increased to keep DCR high it might just get close.

:D


S
 
#20 · (Edited)
Great info Scott, thanks for chiming in.

Whats a 3 pattern cam?

You mentioned using SCJ heads, Carl suggested TFS and etc. So you feel the benefits of the chamber outweigh the larger ports for this scenario, would you agree with him that P51s are just too large for this though?

Also wouldn't better flowing heads be able to make more power with less cam duration? So wouldn't a lot of this ride on utilizing heads that flow a ton at low/mid lifts with a highly efficient chamber to use the smallest possible cam and the most compression?

Also, what kind of intake would work best? Dual plane or a tall single plane or other?

You mentioned dynamic compression, whats the most you can run on pump gas. I know 11:1 is about the limit of static compression and pump


thanks!!!!
 
#26 · (Edited)
Torino.......to answer some of your questions.....and any body can correct if I'm wrong but....as far as the AIR GAP max hp goes....don't know the max hp..but I can tell you I'm pushing 642 hp at 5700 rpm and 670 ft lbs at 4300 rpm.....while maintaing ove 600 ft lbs from 2500 - 5000 rpm and 19 in of vacuum with a SCJ ported air gap with p51 heads and a smaller cam

As far as SCJ vs p51....the p51 do flow more air but the SCJ has a smaller cross section....the goal is to flow the most amount of air AND keep the smallest cross section you can....smaller cross section keeps your air velocity up and crams/sucks more air into your cylinder for a given displacement. Because of the high air speed.....producing more tourqe...and for what you want tourqe is what your after...SCJ SHOULD be more street friendly..and I feel a SCJ head is a far better choose for your intentions...... I've never been real good at explaining things...sorry if I don't make sense. ..maybe of the big dogs can better elaborate. ..i went with the combo that i did because i like to experiment and try new things....lmao hence. P51 heads small e r cam and a dual plane..and was told by many that this is a "stupid" combo...but you never know whats gonna happen till you try it....but i also spend alot of time thinking about the combo and how this part would affect that part and tried to compliment it the best i could....lot of prep work......I can also give you a cut sheet of my build if you like so you can compare if you like...just let me know
 
#27 ·
I'll throw this in for what it's worth. I had a rebuilt well-running stock 89 460 EFI in my offroad buggy for many years, with all new injectors and sensors. It was factory MAP set-up with multiport, but bank fired injectors. I recently built and installed a 545 with the new torker II EFI and 234/244, 0.562/0.581 lift cam, and I went with mustang EEC-IV computer, which has multiport but sequential injectors, and I was surprised to get a noticably better fuel economy from the new motor.
 
#29 ·
Thanks for the input guys.... now I kinda wonder what i could possible hope for if I went ahead and built the 545 I was planning while still aiming for high efficiency with a carefully chosen cam and super tight quench area and eventually efi
 
#32 ·
If I went EFI, the Mustang computer wouldn't be my first choice. If budget was of no concern I would go FAST. If I was to be more budget conscious I would go megasquirt.
 
#33 ·
Man the new FAST EZ EFI with the Carb replacemnt looks like a pretty good setup, but I can't seem to find any info on the throttle body. I'm tempted to order it and try it out
 
#39 ·
The old Ford computers weren't bad, but there are better options for the same price now. Megasquirt would be about the same cost and it will support many more functions than the now nearly 30 year old Ford setup with the same ease of use and amount of support. And FAST XFI will do even more....

So, not to beat a dead horse, but there are options I would choose before the old Ford computers.
 
#40 ·
I think you should shoot for moon.

Caring about gas millage with a bbf ? Common. That's girl talk.

You have a Torino with a big block. You should be able to spank the zo6 not yell out " I get comparable mileage " as he passes you.

You should stick to your original plan.

A high horse Torino is cool. Bragging about gas millage at shows or the track is for the import group.
 
#41 ·
I think people got really sidetracked by the mileage thing. My main concern was not mileage but rather making a good all around combination thats as efficient as possible.

I was asking if I could make 650hp, get 20mpg and it all be a reliable combination that I could drive across the country.

BUT no one ever asks about mileage with these motors so thats what every one focused on. Also as Scott pointed out, hitting that power number AND efficiency requirement would be a real challenge because the cam duration requirements to get to 650hp would start to hurt efficiency.

As far as racing a Z06, those cars are so light and aerodynamic that if the car is modded at all and has a good driver it would take me a lot more power to keep up. Its too easy to make stupid power and go stupid fast with modern cars. This Torino will never be a world beater AND a fun driver and right now I rather it be a fun driver.

I think it would be cool to cruise from Dallas to Vegas or Panama City or whatever and get 20 mpg along the way with out a hiccup while embarrassing all the guys in 5.0s CTS-Vs AMGs and etc along the way. Making that road trip while getting 10mpg and constantly setting the lash and worrying about it breaking doesn't sound like a fun drive to me
 
#43 · (Edited)
Is that car carb or EFI; how much hp; what trans? It also doesn't hurt that its much lighter and a little more slippery than my 71 Torino

Also, I guess you don't adhere to the "no hydro roller cams in BBFs" mentality that others have?
 
#49 · (Edited)
Dam, tried to edit before anyone noticed... I misread it somehow

Glad to see you've got your head screwed on straight. Kind of hard to compete with an $80K car that has world class engineering teams behind it.

One thing that I'm curious about.....how many miles do you plan to drive per year? How much money do you plan to spend on a transmission that will net the desired fuel economy. How many miles will you have to drive to recover the cost of the OD trans vs. getting six MPG less without it?
Yeah, I was never trying to beat a Z06 just benchmark it in a few areas.

I already have both Viper and Magnum T56s to choose from. The car already has the Viper unit in it but I like the Magnum better so I'll probably swap them out. As far as cost vs return, thats not part of the exercise. I just want to be able to pass a few gas stations from time to time. And it ended up with a 6 speed because thats just what I personally wanted to do.

As far as miles I'll put on it goes, I really can't answer that. It really depends how nice a driver I can turn this into. I have a coil over front suspension, rack and pinion, hyrdaboost and big brakes waiting to go on the car sooner than later. At some point it'll get a real AC and radio too

Maybe I'm just nuts, but I have a 3.90 gear in my car right now, and I've got an entire separate 3rd member with 2.75s for if I ever want to take it on a real road trip (over 1000 miles is a "real road trip" to me), or go to Bonneville (one of my goals in life). But, with the 3.90s, I'm getting about 10 mpg, and like Carl stated, cost vs time for the return in saved gas money is a big thing why I haven't gotten an OD yet. But, swapping a different 3rd member is really only about an hour job at most if I ever want to.....but it's soooooo much fun with the 3.90s :D. I don't like the thought of the extra revs on the engine, though.....
But with a 6 speed I can run 4.10s out back and still cruise on the highway and never have to worry about changing a thing.
 
#46 ·
Maybe I'm just nuts, but I have a 3.90 gear in my car right now, and I've got an entire separate 3rd member with 2.75s for if I ever want to take it on a real road trip (over 1000 miles is a "real road trip" to me), or go to Bonneville (one of my goals in life). But, with the 3.90s, I'm getting about 10 mpg, and like Carl stated, cost vs time for the return in saved gas money is a big thing why I haven't gotten an OD yet. But, swapping a different 3rd member is really only about an hour job at most if I ever want to.....but it's soooooo much fun with the 3.90s :D. I don't like the thought of the extra revs on the engine, though.....
 
#47 ·
what spline axles are you using? if you guy anything, it should be a minimum of 31 spline axles if you already dont have them. if you have 28 spline, i've heard people can twist them but i haven't heard anybody really twisting them often but i have though. if you need to upgrade like i did, might as well hit up the 35 spline range. its not too much more.
 
#55 ·
For fuel mileage go with the efi. Sounds like you have spent $$ on your car, don't cheap out and use the eec-iv. It would work, but is very old tech. You'd be limited to a distributor and single coil. You also can't use a wideband O2 sensor to control afr. I use the megasquirt2 but I bought it 4 years ago. If I had to do it now I would recommend the new Holley Dominator efi. Hands down it's one of the nicest systems available for the cost. It is self learning and can control nearly any system you desire (TBI, Dual TBI, MPFI, Drive by Wire ) along with standard and LS/DIS Ignitions. You can do sequential efi timing the injection on a closed intake valve, crank trigger for rock solid timing control and use individual coil on plug. It is the latest and greatest. Megasquirt3 can do that too but it's much more work to set it up. You'll be able to run a water injection system and higher cr with the system controlled by the aftermarket efi for potentially better mpg. I like the idea of what you are trying to do, good luck with it. The aftermarket efi just gives you a lot more options to help in your quest. Also in my experience the efi will help in taming a larger cam at low rpm vs a carburetor which will help you in the hp area.
 
#56 ·
I would do a stroker blower combo.let the blower make all your h/p. use a custom roller cam that easy on parts.p51 heads.procharged with a t56 of some sort.high rpms are a bitch to have to maintain al the time. ive got a 331 dart afr headed blower set up makes around 550 hp w 93 octane with a ****y holly 174 at 5 lbs of boost.im sure you can get to 6-800 hp easily with a stroker ans some decent heads. while maintaing durability,longevity and economy.
 
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