5.7 performance in a abody

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o1heavy

o1heavy

1974 dart sport
Joined
Jan 7, 2009
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tarkington
kicking around the idea of putting a 5.7 hemi in my dart sport
got a few questions currently running a 360 street car ran a best of 12.50s


how does a stock 5.7 run (prolly use a carb )
what trans are you guys using ( i'am ok with the old 3 speed)
headers are available

i got a bunch more but these are the most important

thanks guys
 
I've got a stock 5.7 in my Dart so far and am loving it! I started with a carb swap and wasn't very impressed with the power, but I think I could have fixed it with tuning. I didn't have the parts or equipment to tune it up right, but there's no reason a well tuned carb couldn't make as much power as EFI. When I first swapped it I think I was probably making 300 hp or less on the carb according to my little windshield mount accelerometer. It still woudn't turn the tires on a full throttle stab the way I thought it should. Some of that might have to do with the cam as well. The stock cam is likely designed around EFI, so a carb might not react as well to the valve timing. Swapped over to a Megasquirt fuel injection setup and it's the animal I always thought it should be. I can barely go full throttle in first without hazing the tires or just flat out blowing them off. Should be making between 350-400 hp now according to the same accelerometer.

I've got a plain old 833 four speed behind it now and it's been doing pretty good. Don't have an official timeslip yet since the track here isn't open for the spring season just yet, but I paired it up with my parents XJR Jag that's a 370 hp superchaged car around 3800 pounds and overtook it pretty easily once the tires hooked. I'm hoping for low 13's on a good run. My car scaled in at a little over 3400 with me in it before the FI swap and a fiberglass hood. I think it should run similar to my mom's 99 Vette. It has 350 hp, 350 ft-lb of torque and around the same weight of 3400 lbs and is supposed to run 13.3-13.5 from what most tests have seen. Calculators put my car in the high 12's, but I think that's a pipe dream of a 100% perfect run on a perfect day with zero traction issues.

The nice thing about the new hemis is that they are pretty easy to pump big power out of and still be streetable. Heads and a cam and you can push 400 rwhp pretty easy and still drive it around all day.
 
If you're planning on running a carb on a new Hemi, you're wasting your time and money. You can build a stroker small block cheaper and easier. I'm putting a 5.7 Hemi with the factory fuel injection and a 5 spd automatic transmission in a 70 Duster. If I'm going to finally come into this century...I'm gonna stay here instead of running back about 5 decades to get a carb.
 
JDMopar said:
If you're planning on running a carb on a new Hemi, you're wasting your time and money. You can build a stroker small block cheaper.
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I disagree with your opinion on this. Carbs have been serving reliably for decades and decades. Plus they are plentiful and cheap in used rebuildable condition. If starting with nothing and building engines of equal power output
The 5.7 is competitive with an la stroker in both total cost to build and power in a carbed configuration.

I do agree that efi is superior in most applications but some would rather deal with the simplicity and familiarity of a carb.
 
Cevidicus said:
I disagree with your opinion on this. Carbs have been serving reliably for decades and decades. Plus they are plentiful and cheap in used rebuildable condition. If starting with nothing and building engines of equal power output
The 5.7 is competitive with an la stroker in both total cost to build and power in a carbed configuration.

I do agree that efi is superior in most applications but some would rather deal with the simplicity and familiarity of a carb.
Click to expand...

Agreed, efi offers better drivability and cold starts but when tuned properly, the engine cannot tell the difference at wide open throttle.
 
JDMopar said:
If you're planning on running a carb on a new Hemi, you're wasting your time and money. You can build a stroker small block cheaper and easier. I'm putting a 5.7 Hemi with the factory fuel injection and a 5 spd automatic transmission in a 70 Duster. If I'm going to finally come into this century...I'm gonna stay here instead of running back about 5 decades to get a carb.
Click to expand...

This subject has started many a shouting match and argument so I will keep it simple and true to the fact with no opinions and not comment any further. #1 using fuel injection or carburetor depends on how you want to spend YOUR money!! This is America!!! #2 Go with what suits your abilities and don't be pushed into going over your head due to peer pressure!!(if you don't know how to program fuel injection but you know how to set up a carb use a carb). #3 STOP THE OPINIONS UNLESS ASKED FOR ONE!!! He asked for help not IMO!! This opinion gets to me becaused I get razzed all of the time for having a carbed hemi FOR NO REASON! It runs 11.50s in the quarter naturally aspirated, with a stock displacement 5.7L with 5.7L heads. If you are hurt or bothered by this post I mean no disrespect but remember it nextime.:eek:ops:
 
JDMopar said:
If you're planning on running a carb on a new Hemi, you're wasting your time and money. You can build a stroker small block cheaper and easier. I'm putting a 5.7 Hemi with the factory fuel injection and a 5 spd automatic transmission in a 70 Duster. If I'm going to finally come into this century...I'm gonna stay here instead of running back about 5 decades to get a carb.
Click to expand...


i agree. just don't see the point in going with a modern motor just to go back to the stone ages with a carb. take advantage of the technology. don't know why mopar guys are so afraid of technology. its actually comical. but hey its not my money.
 
Due to my choice I am no longer an FABO member. Goodbye guys!!!
 
hemijoejr said:
Due to my choice I am no longer an FABO member. Goodbye guys!!!
Click to expand...

it's prolly due to some of the clowns that post on this site about stuff they no nothing about... bummer dude.. stay around and ignore the trash!
 
hemijoejr said:
Due to my choice I am no longer an FABO member. Goodbye guys!!!
Click to expand...

so long..
wave.gif
 
Jesus Jones!! Some of y'all sound like menopausal old women! He wanted to know what he was getting into, and I offered an opinion. I stand by it, and if you don't like it.....TFB! :banghead:
 
I think it's a great idea. I plan on running a toilet bowl injection on my 65. What I plan to run is from "affordable fuel injection", they take the cheby style set up and work the vcm to accomidate your HP. Not bad for 1K considering the others are twice the price. Post some pics when your done.

Once you understand how the componets work with EFI, the rest is easy.
 
I've expressed my opinion pretty strongly on the Carb vs EFI question. I definitely think EFI is the way to go, and if you go megasquirt you can do it for about the same price as a carb.

I feel bad that HemiJoeJr is taking off. That being said, often when someone says they plan to go carb, I would argue that they do so out of fear. The fear that they will never figure out the EFI, and based upon some of the difficulties guys have had with the factory EFI there is some justification to that fear.

For the above reason, when someone says they plan to go carb, I frequently chime in to say, "Hey, don't throw out thirty years of auto technology quite yet." I won't apologize for that.

Finally, a well running 5.7 Hemi with a cam and headers is a honest 400 HP motor. Hot-Rod got 481 out of a 5.7 with headers, cam, single plane manifold. The long runner factory EFI will provide a ton more torque, but sacrifices some top end HP. As a result with perfect conditions a flat 12 second quarter mile time is certainly possible, though high twelves is much more likely given likelihood of traction issues and not having the gear ratio optimized for quarter mile times.

To me the real beauty of the 5.7 / 6.1 Hemi is the fact that you could have 400-750 HP and still have a very streetable combination.

Regards,

Joe Dokes
 
i'am up to speed and not afaid of technology
but this is for diesal trucks(mack trucks) and not very useful for automotive opinions dont bother me guys


so most of you are not running the factory injection ?

the megasquirt sounds like it could be interesting
 
o1heavy,

A lot of guys do run the factory computer with fuel injection. Most with good results. Unfortunately some have run into difficulties, and the factory ecm is limited it its ability to deal with changes like cams, porting, and superchargers. Early centrifugal blowers had the bad habit of destroying hemi engines. Those problems have been dealt with and the kits from Kenne Bell, Paxton, etc are now reliable.

All that being said, the factory ecm with a wiring harness from Hot-Wire or Street and Performance has served many FABO members well.

If you want full control over fuel and spark you have a few choices.

Mopar Performance sells a kit, that is basically a rebranded AEM unit, it comes with an 80mm cable operated throttle body.

FAST sells a kit that uses one of their 92mm GM style cable operated throttle bodies and an adapter

Megasquirt is a DIY controller that can be fitted to virtually any engine. As a result it is NOT very user friendly.

You can cut and splice the stock hemi wiring harness and use all your factory sensors. You are pretty much on your own for wiring up your megasquirt but as you read more and more you'll come to realize that it is not that complicated, just a butt load of wires.

You will need to adapt a cable operated throttle body as Megasquirt does not support drive by wire. I made my own adapter to use a GM LS style cable operated throttle body, or you can buy an adapter from FAST for $68.00. The GM throttle body will use a common GM throttle position switch and Idle Air Control Valve.

To cut a long story short, Megasquirt is approximately 1/3 the price of FAST and 1/4 the price of AEM unit. MS is truly DIY you can either buy a prebuilt unit or get out your soldering gun and build your own. You'll save about 200.00 if you can solder.

In addition many in the community who have used both AEM, FAST, and Megasquirt tuning software actually like the Megasquirt software better.

Also and this was important though not critical, the Megasquirt tuning software is written in Java so it has been ported to Mac OS X. It was important to me as I have a Mac and although I could load Windows on it, I didn't want to spend the money on a Windows license if I didn't have to.

Here's a couple of links to get you started

http://www.ms3efi.com

http://www.diyautotune.com

Hope this helps.

Regards,

Joe Dokes
 
deciding on a 408 or a 5.7
not in a hurry just freshed up my 360 and it should be good for a while
the 5.7 is interesting and 450-475 hp looks as if it can be done

efi will be the way to go after reseaching the carb cost

thanks for the input

the efi vs carb thread is very helpful
 
I've always hated carbs, useless dinosaur technology IMO. But in instances like a drag car where the car is making a bunch of passes one day a week and not street driven I see no problems using a carb. The only real difference between fi and carbs are the fact fuel injection can adjust on the go. Once you get into mpfi(multi port) then you get more away from a carb, and once like a diesel we have direct gasoline injection then we'll have a monster far separate from carbs. Would I carb a hemi? Not at all. Do guys deserve crap because they do? Not at all. Comfort level is important.
 
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