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engine upgrades?

5K views 16 replies 7 participants last post by  ECONORAM 
#1 ·
I've done just about every external bolt-on possible, and while my truck has plenty of low end and will lay stripes, it's still not fast by any stretch.
From idle to 3500 is great, from 3500 up is not.

What is the 360s design flaw that makes it so inefficient?
I'm getting 9 mpg - empty, full, towing, not...9 all the time.

I know the heads are probably cracked, but what else could be improved?

I'm talking about single parts - cam, higher compression pistons, etc.
nothing like a larger displacement stroker kit.

With almost 200k on the motor I'm probably losing some to compression, but with the tune, throttlebody, roller rockers, long tubes, etc it should do a little better than 9.

I just want to have a list put together when it's time for a rebuild so I know what direction to go.
 
#2 ·
a cam is going to mover your power band up which will give you more top end.
higher compression is going to be a bottom to top power inprovement
none of these are going to help with fuel mileage however

i got better then 9mpg out of boost with my last built which was 10.6:1 compression. cam had a ton of lift and duration but on a 114lsa
if you interested in mpg rebuild it to stock specs with maybe a little cam and a new set of heads.
 
#3 ·
new heads will boost compression a bit, plus 1008 felpro head gaskets. and a M1 manifold should do you pretty good.
 
#4 ·
You can come drive mine! Slowest truck on the planet but at least I get 12mpg!!
 
#5 ·
lol your running larger tires and a lift with 3.55s
My 97 with the 318 was a pig after I put the 35s on until I upgraded to 4.11s
The 01 I am working on now is getting 4.56s so that should help some, but it'a also got almost 200k hard miles.

When the time comes I was looking for internal upgrade options.

I have seen an airgap (m1?) intake for around $350 at some of the swap meets, but wasn't sure what the advertised power range was.
A little more lift & duration on the cam along with a new set of IronRam heads would probably help with flow.

If the metal sleeves for the spark plugs werent rusted in place I'd do a compression check...
 
#6 ·
My truck could never move its butt, even on stock 245s. It also has the Deathflash. Only time I feel it is moving, it at 150 temp just before it gets to 180. Then it falls flat on its face.

Gears are out of the question. I was quoted nearly $3000 and the truck is worth maybe half that.
 
#7 ·
I'm in the same boat, I've now invested more money into the truck than what I paid for it ($1800), and almost more than what it blue books for ($2750). The trans was right at $1000, I'll have close to $700 in the rear axle replacement and front & rear re-gearing, and that's not counting labor.


the death flash is what's killing the power.
You anywhere near TX?
 
#13 ·
I've gone one step further than Chizzle1. I've pulled everything off my short block except the crank, pistons and oil pan. I've also pulled my tranny and installed a 2800 RPM stall convertor. I also have Mopar Performance mid length headers going out to 2.5" pipes to an X pipe and then to true duals out the back. I replaced the cam with a KRC 210x variant (was supposed to be the 210x but they sent me a slightly more radical grind with faster ramp rates.. oh well) with 1.7 rockers for a full .538 lift on intake and exhaust. M1 intake with F&B 52mm throttle body. I found out about the head cracking problem so I went with street ported R/T heads. They have the castings cleaned up and the bowls blended with 6062 springs installed with screw in studs and guide plates. Also have a MSD 6AL and the HVC coil.

I had it tuned by HemiFever with my SCT X2 programmer. I was told by Marty at KRC back in the day that I should be pulling 420 hp at the crank. I figure about 300 hp at the rear wheels since I have a 4x4 and that transfer case is a power sucking beast along with the tranny. I had plans at one time to install 4.56 gears to replace my 3.55 gears but the mileage sucks the way it is. I get about 10.5 MPG in town and about 12.5 to 13 on the highway. Revs really well. I shift at 5700 rpm in all gears thanks to the APS valve body along with the HemiFever tune.

Before the mods I got just under 14 MPG no matter where I drove but after the mods and stall it dropped down to where it is now. Its fun to drive but I recently got laid off at my old job and have to travel farther to my new job so its not a daily commuter vehicle anymore for me. You would think with all the mods and if I kept my foot out of it the mileage on the highway would improve but it doesn't. I have been thinking about getting a mileage tune from Hemifever but I shudder at the thought. Its about 20 years old now and starting to show its age. I bought this baby brand new so it has a special place in my heart.
 
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