EFI S/C question in 68 coupe...

[tjnavyblue]

Hi Guys,

I'm working on my long range plan for the car (1968 coupe) and would like a few thoughts from ya'll.

I'd like to do a 5.0 EFI with a T5. I already have a three speed on the floor, so the manual swap will most likely be easiest. I'm looking for around 300-350 horsepower and 25 MPG hwy with good longevity (running all synthetics, a good tune and good tire pressure I think this should be doable...?)

The way I plan on acheiving that is through a mostly stock roller 5.0 with bolt on mods inlcuding a good set of long tube headers, a good intake, a cam, and a supercharger running 5 - 7 lbs of boost. The reason I'm drawn toward the supercharger is because (correct me if I'm wrong) it will not hurt fuel mileage during normal driving conditions, but will still deliver good power when asked.

My questions are:
1.Assuming I can find a low mile 5.0 (that doesn't need an instant rebuild), will the stock internals handle a supercharger running low boost?

2. Will this 'bolt on' set up achieve my h.p. objectives without compromising mpg on the hwy?

3. What is the best s/c for the application?

4. If I bought a s/c kit, would I buy it for the Foxbody or for a 1968?


Thanks in advance all...

 

[iskwezm]

1. Stock internals will handle about 5-7 psi boost.But if your going throught the hassle and expence of doing a engine swap, dont put in a "used" engine.At least rebuild it with some new rings and bearings and gaskets.

2.You should get what your looking for with a blower.

3.Since your going for a low boost set up,dont waste the money on a Novi2000 pr Procharger set up. Just get a old school Paxton(Paradise Wheels has the SN kits still for cheap)

4. Since your going with a EFi set up, there wil be some modifying that you will have to do,no kit will fit perfectly,But a kit for a 5.0 EFI is your better choice.

If your not mechaincally inclined,set aside money to for labor and fabbing up parts and a lot of it. Tuning it something you probably cant do yourself and that will also be pricey.

 

[tjnavyblue]

Hi, thanks for the tips.

Is the Paxton you're running (in your sig. iskwezm) the same one you're recommending? So it does have the potential for running atleast 10 psi...(who knows what I'll be tempted to do in the future )?

Also, as long as I'm freshening up the motor with new rings etc., is there anything I really should do while it's apart (aside from replacing everything with a forged setup)?

As far as price goes - I've read a few times on here about guys who have pieced together a supercharger kit for around $1000. Is that realistic?

My level of mechanical inclination is high on enthusiasm and lower on experience.
There's pretty much nothing I don't want to atleast try my hand at - especially with fabrication and stuff. I don't have the dinero$ to pay someone else to try their hand at it. I've restored a few cafe racers (pics of my bike: http://kzrider.com/component/option,com_joomlaboard/Itemid,/func,view/catid,10/id,51737/#51737 ) , but that's not on the same scale.

Anyway, thanks for the help. What did backyard mechanics do without forums and the internet? Learning all this by trial and error would take a lifetime.

 

[iskwezm]

Hi, thanks for the tips.

Is the Paxton you're running (in your sig. iskwezm) the same one you're recommending? So it does have the potential for running atleast 10 psi...(who knows what I'll be tempted to do in the future )?

Also, as long as I'm freshening up the motor with new rings etc., is there anything I really should do while it's apart (aside from replacing everything with a forged setup)?

As far as price goes - I've read a few times on here about guys who have pieced together a supercharger kit for around $1000. Is that realistic?

My level of mechanical inclination is high on enthusiasm and lower on experience.
There's pretty much nothing I don't want to atleast try my hand at - especially with fabrication and stuff. I don't have the dinero$ to pay someone else to try their hand at it. I've restored a few cafe racers (pics of my bike: http://kzrider.com/component/option,com_joomlaboard/Itemid,/func,view/catid,10/id,51737/#51737 ) , but that's not on the same scale.

Anyway, thanks for the help. What did backyard mechanics do without forums and the internet? Learning all this by trial and error would take a lifetime.

well now you've just changed your whole game plan

I picked up my shortblock with forged rotating assembly for about 2300 bucks, add heads,intake,carb,headers,electrical and front accessories and thats about it

Sure you can piece together a blower together, but you can also open a can of worms with a bad impellar or bearings,then youve just spent your savings on a $600+ rebuild.Mine complete ran me $2K. They can do 10 psi,but they arent very efficient at that level.You have to watch the impellar speed,they are limited to about 42,000 rpm i think.

I always try to do things the "cheap" way, and i'll show you the stack of parts i have from doing things twice.

 

[BB1966]

Just buy my car and bolt a S/C on it and go........

 

[tjnavyblue]

Yeah, I didn't word that very well. I meant what can I do besides going full bore and getting a forged rotating assembly. Sorry for the confusion. Game plan is still the same.

BB1966 - maybe we could just trade cars straight across?

 

[GNN60GT500]

My fastback I sold had a stock 5.0 with 85,000 miles- all stock internals- running 7 pounds of boost and driven hard-

ran like a champ for the 20,000+ miles I had the blower on- sold the car too my uncle, and the thing is still running strong-

I used the NOVI1000 on mine-

 

[ForceFed70]

Keep in mind that a supercharger is going to be hard on fuel economy. Doesn't matter how you drive it.

I think a stock 5.0 HO engine with hypereutectic pistons would be good for 5-7PSI. It's kinda a gamble as to wether you should rebuild right away or wait until there is a problem. Just keep in mind it's not a matter of "If" it's a matter or "when".

 

[red65]

Since you're planning on a fairly modest horsepower target, you might rethink using a supercharger. When I first installed my 5.0EFI into my '65, it had a Holley Systemax heads/cam/intake setup, that was advertised to make 350hp (at the flywheel I assume). That was a very drivable combo that idled reasonably well, started every time, and was lots of good fun when you got on the loud pedal. It didn't even require a custom tune on the EEC-IV - I just bolted it all together and drove.

A year or two later, I lost my mind and installed a Novi 1000 S/C. I started with a Fox 5.0 kit, which is a good starting point, as iskwezm recommended. It was a significant effort, though, and took lots of time and garage-floor engineering. Enthusiasm won't pull you through here - you're going to need some genuine fabrication and shop-floor engineering skills to pull it off. By the way, the car ultimately dynoed at 445rwhp, and has crossed the line from 'good fun' to 'oh my god.' Driveability is not as good, although it's still pretty well behaved - a custom dyno tune was a necessity ($$!). Gas mileage is not something I track anymore, but suffice it to say that I'm jealous of those economical Suburbans and Yukons.

Given your target, I'd think about a simple head, cam and intake swap, and nix the S/C for now. Holley is one among many possible options - you can collect lots of opinions on this on Stangnet. I think the money may work out better too. You can always add the supercharger later, once some testosterone has pooled in your brain and you lose your mind too... Good luck.

 

[68EFIvert]

I have a 68 vert that I've converted to EFI. I did the cam, head, intake, injector, pulley, 1.7 roller rocker, balanced bottom end, forged pistons, long tube coated headers with flowmasters ........ In general I built it for good fun and reliability. I think it will be putting out 330-350 hp. I have kicked around the same idea that you are contemplating, adding a sc to my package and built my engine with it in mind. I don't think it makes that much sense for me now. If I feel that I really need more power I now plan on adding a ZEX wet NOS setup for that occasional wild hair but leave good enough alone for now. Nothing like another 125 hp at the flip of a switch.

 

[tjnavyblue]

Thanks for the feedback.

From my reading on other threads I was under the impression that the supercharger wouldn't necessarily affect mpg because it wouldn't get spooled up under normal driving conditions...? Any more thoughts on how this works?

The reason I was wary of changing heads, intake and cam etc. was that in increasing flow, I would be decreasing mpg... (red65 - what was your experience?). However, maybe 350h.p. and 25 miles per gallon just isn't a reality. Though at some point, shouldn't taking a stock engine and making it as effecient as possible increase h.p. and possibly even decrease fuel consumption?

I've read posts on here of guys reaching 26 and even 27 mpg hwy with well tuned 5.0s. Gas is three bucks a gallon again, and my sentiment is that if I'm gonna build a car I want to be able to drive it everyday without killing the wallet.

I appreciatte those warnings about the fabrication skills required. I'm feeling mixed on the S/C idea for sure. I did swap a few brief emails with the guys from Paradise Wheels and interestingly they can put together a hybrid kit which shares components from the Foxbody kit and the old Shelby style kit and, presumably, cuts down on the fabrication required. They said it would be "cheaper than the Shelby style kit".

Thanks for thinking through this with me.

 

[tjnavyblue]

Here's a link to a good thread in 5.0 tech on fuel mileage. This is what got me thinking in the direction I indicated at first.

http://forums.stangnet.com/showthread.php?t=534229&highlight=supercharger

 

[iskwezm]

Thanks for the feedback.

From my reading on other threads I was under the impression that the supercharger wouldn't necessarily affect mpg because it wouldn't get spooled up under normal driving conditions...? Any more thoughts on how this works?




I appreciatte those warnings about the fabrication skills required. I'm feeling mixed on the S/C idea for sure. I did swap a few brief emails with the guys from Paradise Wheels and interestingly they can put together a hybrid kit which shares components from the Foxbody kit and the old Shelby style kit and, presumably, cuts down on the fabrication required. They said it would be "cheaper than the Shelby style kit".

Thanks for thinking through this with me.

I dissagree with the comment about a "supercharger being hard on gas mileage".Unless its spoken from experience its a "guess". I dont measure mine, but i doubt i lost any.True it does take about 20-30 HP to spin a blower, but what what you gain back in torque/HP makes up for it and the extra torque is what makes the car move easier,therefore using less gas to move it.

Craig at Paradise Wheels is THE MAN for old school kits and there can be a lot of threads about him found on superchargerhelp.com.He bought all the rights to the SN ball drives, so for parts he is the only place to go.

 

[BB1966]

BB1966 - maybe we could just trade cars straight across?

No ,But you could be riding this summer for WAY less than building one..My car is already EFI ,5 speed and the fuel system will cover the SC no problem.

 

[ForceFed70]

I don't speak from experience, but I wonder how you could convince yourself any other way? True, you might be able to get decent gas mileage while keeping a supercharger, but you will always be better without.

Iskwezn, you said yourself that it takes 20-30hp to spin the blower (personally I think it would be more I've heard 25% of HP goes into spinning the blower). True, you make up for that lost HP... but any way you look at it, it takes fuel to make horsepower. Those 20-30Hp arn't magic ponies that run off of air...

There is alot to be considered here. But any way you look at it... strap on a SC and your fuel mileage WILL go down. Especially if you want to run a "safe" aka rich tune.

 

[red65]

The reason I was wary of changing heads, intake and cam etc. was that in increasing flow, I would be decreasing mpg... (red65 - what was your experience?). However, maybe 350h.p. and 25 miles per gallon just isn't a reality.

My gas mileage went from "who cares" to "wow, my mileage is really bad," but I never bothered to measure it. I'd guess it dropped from teens to single digits. Ask yourself, seriously, if the amount of fuel you're going to use with this car is a major factor. If it is, to be blunt, you're just barking up the wrong tree.

The Fox Mustang I had years ago - a '92 GT convertible making its bone-stock 225hp - maybe (maybe) made 25mpg in straight highway driving if I ran downhill and the wind was at my back; but I didn't buy that car for its fuel mileage either.

 

[iskwezm]

I don't speak from experience, but I wonder how you could convince yourself any other way? True, you might be able to get decent gas mileage while keeping a supercharger, but you will always be better without.

Iskwezn, you said yourself that it takes 20-30hp to spin the blower (personally I think it would be more I've heard 25% of HP goes into spinning the blower). True, you make up for that lost HP... but any way you look at it, it takes fuel to make horsepower. Those 20-30Hp arn't magic ponies that run off of air...

There is alot to be considered here. But any way you look at it... strap on a SC and your fuel mileage WILL go down. Especially if you want to run a "safe" aka rich tune.

Being that i used to work for a company that made superchargers and did extensive testing to prove results, im not just talking out of my a$$.basically its increasing the VE of engine since most engines can only acheive about 85% VE. But if you do a little research, you will find under normal driving(which is what anybody would do for maximum fule economy) gas mileage could increase.These are just a few comments from other companies that dealt with the myth of "losing gas mileage"


"Does the supercharger decrease my fuel mileage?....... Not under normal driving conditions. However, if you use the boost it will, of course, use more fuel. You can't make power without fuel."

"Boosting, or adding a supercharger to a stock naturally-aspirated engine, has made something of a comeback in recent years due largely to the increased quality of the alloys and machining used in modern engines. In the past, boosting would dramatically shorten an engine's life due to the extreme temperature and pressure created by the supercharger, but modern engines produced with modern materials provide considerable overdesign and boosting is no longer a serious reliability concern. For this reason boosting is commonly used in smaller cars, where the added weight of the supercharger is less than the weight of a larger engine delivering the same amount of power. This also results in better gas mileage, as mileage is often a function of the overall weight of the car, a sizeable percentage of which is weight of the engine. "

"A supercharger is the most versatile form of power adder. The power is available "on-demand" at all times, but when the supercharger is not making boost it takes only minimal power to spin. As a result, in normal driving mileage does not decrease significantly. This common myth is just that, a myth. In fact, some of our customers have reported an improvement in fuel economy under normal conditions after a blower installation. Most likely this is due to the careful tuning we do for each of our own installations."

Theres plenty other comments from tuners as well as manufactures, but im sure you could find just as many opposing this view.But from MY experience, under normal driving conditions,it does not decrease mileage.If your foot is always in it, then yes it will.

 

[GNN60GT500]

wow...is this StangNet or PriusNet ?

Ive added superchargers to several cars in the past and the only time I saw a drop in gas mileage was when my foot was in it all the time-

just cruising I never saw a difference-

If you are so concerned about MPG, keep the motor stock or buy a daily driver-

I would have to say the last thing I think about when building a car is MPG-

My daily driver (Lexus IS350) puts 265 to the rear wheels, and will get 25-27MPG if I keep my foot out of it- but the way I drive it I get about 20MPG (the thing also ran a 13.38@105MPH - not bad)

Of course if I was going to pu**y foot it all day long, I would have bought the 250 and gotten 30+ MPG

BTW- off topic- I need a 4 door car for work- when is Ford going to build a 4 door that is fun to drive? I would rather have a Ford-

 

[BB1966]

BTW- off topic- I need a 4 door car for work- when is Ford going to build a 4 door that is fun to drive? I would rather have a Ford-[/QUOTE]

They do,just in Austraila ..........The Falcon!

 

[68efisuper]

I have a 68 with a 5.0 motor and a kenne bell supercharger. The motor has performance heads, exhaust, cam and made 379 to the rear wheels on the dyno. I can still get 18-20 mpg on a highway drive. Around town you can just forget it, its too much fun to use all that torque