How much compression will a magnum take?
#11
04-07-2016, 06:44 AM
Record Breaker
#12
04-07-2016, 09:54 AM
The stock bottom end will take a lot of abuse even with Boost and Spray, it's all about the tune....But again, I don't see anything you are doing to cause any concern.
I know my Dakota is running Eddy Heads, but I run 91 pump gas on 11.5:1. As said...It's all about the combo and tune
I know my Dakota is running Eddy Heads, but I run 91 pump gas on 11.5:1. As said...It's all about the combo and tune
Ya, finding a tuner in Central Florida that actually knows how to tune, not just program, is going to be a challenge.
I have a 3.9 in it now. I have the '96 engine in a van and it isn't fast enough for me, and it needs rebuilt. Because I need to be able to tow with it, I have to keep the cam smaller than I want. Still, I'll get 330-350 hp out of it, and I am trying to reach 21 mpg.
Since I am changing the top end, I should be able to squeeze a little more out of it. I just need to find out what is the limit for CR
Spending $600 for good intake pisses me off--even though I am use to paying more for parts being a Dodge Boy.
I have a 3.9 in it now. I have the '96 engine in a van and it isn't fast enough for me, and it needs rebuilt. Because I need to be able to tow with it, I have to keep the cam smaller than I want. Still, I'll get 330-350 hp out of it, and I am trying to reach 21 mpg.
Since I am changing the top end, I should be able to squeeze a little more out of it. I just need to find out what is the limit for CR
Spending $600 for good intake pisses me off--even though I am use to paying more for parts being a Dodge Boy.
I saw 19.5 highway back when all I had done was flowmaster cat-back exhaust otherwise stock. 4.5hrs at 65mph with no wind and 75-80degrees out no hills.
#13
04-08-2016, 05:53 PM
Veteran
FlyinRyan is in Florida so you have one of the best Magnum tuners in you backyard. I can't tell you yet what grade of fuel I'm going to have to use but I'll be running about 10.2:1 CR on my rig.
21MPG is not going to happen out of a magnum engine. You will see people all the time saying they get that but I really think their math is off.
21MPG is not going to happen out of a magnum engine. You will see people all the time saying they get that but I really think their math is off.
http://www.frptuning.com/
#14
04-11-2016, 09:25 PM
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It's all about the entire system design. Small quench area reduces tendency for spark knock, and you can push compression/timing pretty good. It is truly unfortunate that Dodge, in their finite wisdom, didn't decide to put a knock sensor on these engines, so the computer could run max timing, and only pull as necessary.... Instead of having to program for constant 'worst case scenario'.
if you keep quench area to a minimum, and are gentle with timing, (which will rob power) you could do 9.5:1 on regular gas....
if you keep quench area to a minimum, and are gentle with timing, (which will rob power) you could do 9.5:1 on regular gas....
I couldn't agree more about the knock sensor.
I was hoping with the better quench area on these heads would allow me to raise the compression to say, 9:3, and still not have to worry about detonation.
As for the timing, I had hoped the PCM engineers had it programmed to run the max timing without detonating, but from what you say that ain't gonna happen. Will have to see what the programmer can do, I guess.
#15
04-11-2016, 09:37 PM
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9:1 is factory and the factory heads are 62cc. The EQs don't raise compression at all unless you shave them or use a thinner gasket or both.
Good buddy of mine and a guy who used to be on here (Merc225hp) runs 10.5:1 with a custom grind, 1.7s, shorties with 2.25 true duals xpiped, heads comparable to the EQs, #24 injectors and 2bbl M1 ALL controlled through a MoparPerformancePCM
Good buddy of mine and a guy who used to be on here (Merc225hp) runs 10.5:1 with a custom grind, 1.7s, shorties with 2.25 true duals xpiped, heads comparable to the EQs, #24 injectors and 2bbl M1 ALL controlled through a MoparPerformancePCM
I looked at the MP PCM and was all set to order it and then I read it is not intended to be used on the street. I remember decades ago when Mopar started coming out with the different color ignition boxes and the trouble we had getting the strip version wired up for the street and not eat coils. Could it be similar with this PCM? Will they even last for continuous duty or 150,000 miles? Anybody know?
#16
04-11-2016, 09:50 PM
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Well, Spillage ol' boy, just remember to check back in on this thread every few months. The secret is to get good flow from air filter to muffler. Just think of the engine as a system where each part either enhances or hurts other parts.
Would you believe 16 mpg in a '70 Challenger 340 Six Pack with a 299*duration and .509" cam, 10.3:1, 3 speed auto, and 3.91 rear? They said that couldn't be done either.
With horrible exhaust manifolds gone, correct headers (and I don't mean those ridiculous shorty headers either) will gain me 2-3 mpg right there. As long as I don't put in too big a cam (which will also hurt being able to tow) to reach the 350 HP goal, I should reach 20 mpg easily, and likely 21 mpg-with a 3:55 rear end.
#17
04-11-2016, 10:03 PM
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[QUOTE=dapepper9;3292133][QUOTE=Wildman4x4nut;3292098]FlyinRyan is in Florida so you have one of the best Magnum tuners in you backyard. I can't tell you yet what grade of fuel I'm going to have to use but I'll be running about 10.2:1 CR on my rig.QUOTE]
Got any idea where/what city FlyinRyan is out of?
Got any idea where/what city FlyinRyan is out of?
#18
04-11-2016, 10:08 PM
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Ryan's in Texas now. Katy Texas to be exact. Has a new web page also.
http://www.frptuning.com/
http://www.frptuning.com/
Thanks for the link, RenardK764. Always good to know someone who speaks Mopar--and tuning I am weak on.
#19
04-12-2016, 01:51 PM
I looked at the MP PCM and was all set to order it and then I read it is not intended to be used on the street. I remember decades ago when Mopar started coming out with the different color ignition boxes and the trouble we had getting the strip version wired up for the street and not eat coils. Could it be similar with this PCM? Will they even last for continuous duty or 150,000 miles? Anybody know?
#20
04-12-2016, 05:34 PM
Haven't seen him around here for a while.... Wonder what happened to him.