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tman
Dodge Dakota
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12/13/2002
15:03:16
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 Subject: Boost limits on 5.2 or 4.7
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how much boost can you run on a stock 5.2 or 4.7. and can you go a lot higher with fel-pro or copper gaskets?
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notchlx
Dodge Dakota
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12/13/2002
16:03:18
| RE: Boost limits on 5.2 or 4.7
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Not so sure on either, but, I recently ordered the Paxton kit...
I'm going to start things off at stock boost...6-7psi..I'll see how the air/fuel situation looks, and work my way up from there.
I talked to one guy who installed a Paxton on his 4.7, and it ran fine with 6-7psi, but when he upped it to 10psi, he had some problems...
He did it without compensating for fuel though.
If you want to be safe, I would recommend not going any higher than 8psi on either, and even at that, you have to have the necessary ammount of fuel.
I will push the limits on mine eventually, but to save some headaches, I'll leave it alone for a while.
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Demon Dakota
DakotaEnthusiast
12/13/2002
17:15:47
| RE: Boost limits on 5.2 or 4.7
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The stock internals "could" handle 9-10 PSi based on my research, but fuel and cooling would definitely need to be addressed. Bigger injectors, a stand alone fuel management unit, and some serious dyno time would be ideal, but then it wouldn't really be a bolt on system anymore.
K&N Drop in AF
True Dual exhaust and removed third cat
HO Cams & HO Intake
Modified TB
Autolite 3923 Plugs
TPS @ .76 VDC
IAT Adjuster Mod
14.52@94.2 MPH at Silver Dollar Raceway
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dogliftsleg
Dodge Dakota
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12/13/2002
20:54:59
| RE: Boost limits on 5.2 or 4.7
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I used to own a "79 Turbo Mustang Cobra many years ago. It came factory stock with a high volume oil pump, forged rods, crank, and pistons, and race quality bearings all over the place. It only put out a max of 5.5 lb boost (in factory form, I modified it, using a golf tee to bypass the wastegate, to 9 lb). If I was today going to boost my manifold pressure, due to the experiances that I had with that engine (mostly good, except for the carborator), I would start by making those changes first, before bolting on any type of booster.
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dogliftsleg
Dodge Dakota
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12/13/2002
20:57:20
| RE: Boost limits on 5.2 or 4.7
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Oh yeah it also had a modified head gasket made to with stand the extra internal chamber pressures.
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paysonbadboy
Dodge Dakota
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12/13/2002
21:43:23
| RE: Boost limits on 5.2 or 4.7
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dogliftsleg
, you're talking about the '70 Mustang with the 2.3 Liter 4 cylinder right? Those pinto based Engines were long lasting tanks. I knew people who drove the non-turbo ones for years even with rod knocks! Those were not all that fast tho.
I heard that back in the day, those turbo ones were considered pretty fast. How was it?
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big_torque
Dodge Dakota
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12/13/2002
23:41:41
| RE: Boost limits on 5.2 or 4.7
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I thought you said we are all idiots and that you are done posting here , dogliftsleg.
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tman
Dodge Dakota
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12/14/2002
07:28:20
| RE: Boost limits on 5.2 or 4.7
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thanx guys, but does anyone know which engine can handle more boost? im purchasing a new dakota to replace my 92 R/T and im thinking of going with a 4.7 w/5 speed, or a 5.2 w/5 speed club cab, and want to put a supercharger on it the day i recieve it.
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tman
Dodge Dakota
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12/14/2002
14:05:38
| RE: Boost limits on 5.2 or 4.7
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thanx guys, but does anyone know which engine can handle more boost? im purchasing a new dakota to replace my 92 R/T and im thinking of going with a 4.7 w/5 speed, or a 5.2 w/5 speed club cab, and want to put a supercharger on it the day i recieve it.
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dogliftsleg
Dodge Dakota
JOIN HERE
12/14/2002
15:23:58
| RE: Boost limits on 5.2 or 4.7
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big-torque I told you a while back that some clown stole my name,now I am wondering if you are the clown that posted the flames and put my moniker on it.
paysonbadboy Yeah that was a 1979 Pinto based engine, a few years after they came out with it they took a straight six pushrod engine and cut it down to a four and used it, It was a bit faster and did not have the same problems the Pinto block had with undersize oil galleries that would starve the bearings on some engines and burn up the bearings. True they were not that fast only 17 in the quarter turning 80 when stock with the wastegate bypassed and a tank full of premium you could pull a 15 something at just over 86 mph. Believe it or not the "80 and "81 Camaro Z28 was actually slower against a stock turbo stang in the 1/4 mi but soon GM figured out the new smog rules and that ended that. It took a while to figure out that if I wanted to sprint away after going around a corner I had to open up the throttle almost upon starting the turn so the turbo could spool up and start to produce power about the same time you finished exiting the corner. They aslo came with some pretty awesome tires made by michelin that allowed it corner in the .84 area, which for its time was at the top of the pack. The thing had a ride like a brick and was not all that good for cross country touring. My wife hated it.
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Larry Hearold
Dodge Dakota
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12/15/2002
23:49:41
| RE: Boost limits on 5.2 or 4.7
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I have a 98 Durango with a 5.9 and I run 9 pounds boost on it. Had to go with the ford motorsports competition injectors though (Summit Racing has them) and an MSD boost retard box. Started out trying to use the Mopar performance ECM but it advances the timing too much. Have better luck with the stock unit. Also using MP headers and dual exhaust. Dyno's it and the HP went from 235 before to 355 after and added almost 80 foot pounds torque across the board. Only problem I've noticed is spark plugs. Need to replace a lot more ofter. Not melted, just on the verge of fouling since I went to N9Y Champions. One of these days its going to be impossible to get plugs cold enough for forced induction!!
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notchlx
Dodge Dakota
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12/16/2002
00:26:57
| RE: Boost limits on 5.2 or 4.7
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Larry,
Have you taken the big "D" down the track since the install?
355 is pretty stout. Did you go with a Vortech unit?
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Lew360
Dodge Dakota
JOIN HERE
12/16/2002
01:51:37
|  RE: Boost limits on 5.2 or 4.7
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Larry, I have a few questions for you. Did you replace your head gaskets or the intake? What do you have the BTM set at? The reason I ask is I have a 9lb. pulley but am afraid to install it till I change the Headgaskets. The problem you are having with the plugs is probably because the Ford injectors are making it run pig rich at anything but WOT. I don't know that for sure because my dyno runs have been made with the cat still on, and I think that is throwing off the A/F reading.
'99 RC Dakota R/T, Gibson Headers and Cat-back, MSD 6a, BTM, IAT adjuster, Powerdyne Supercharger, M-1 4/2, Mopar PCM.
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kota on 20s
GenIII
12/16/2002
02:55:07
| RE: Boost limits on 5.2 or 4.7
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lew360, do you want to sell that 9lb pulley?
~Eric
superdupercharged, M-1, 1.7 RR's, 52mm TB, ceramic headers, 3" carsound cat, and gibson muffler
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Lew360
Dodge Dakota
JOIN HERE
12/16/2002
03:46:24
| RE: Boost limits on 5.2 or 4.7
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Kota
No, I will be using it in the near future, I just don't know if I should do the FelPros before or if I can wait.
'99 RC Dakota R/T, Gibson Headers and Cat-back, MSD 6a, BTM, IAT adjuster, Powerdyne Supercharger, M-1 4/2, Mopar PCM.
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kota on 20s
GenIII
12/16/2002
04:15:16
| RE: Boost limits on 5.2 or 4.7
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better safe than sorry
~Eric
superdupercharged, M-1, 1.7 RR's, 52mm TB, ceramic headers, 3" carsound cat, and gibson muffler
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FastRT6Dakota
Dodge Dakota
JOIN HERE
12/16/2002
17:57:23
| RE: Boost limits on 5.2 or 4.7
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ok, this is kinda off topic, but I have to get some opinions on it. I remember an old ad that showed a pro-mod dirt circle car and a picture of its engine. The ad also showed the head gasket and piston from said engine. The piston had a hole burned in that was nearly half the piston head, but the gasket was fine. The ad read "Piston gives, gasket lives." It was felpro. Now, I consider myself to have a fair amount of knowlege about engines and vehicles, but I still don't get it. Why in hell would you rather replace your pistons than a head gasket? Lets compare:
1. Time: Piston change: around 5-6hrs Gasket Change: 45min. (both have been done in my 66 Fairlane. I have actually timed it.)
2. Ease of access: Pull the head to change the gasket, or pull the engine to change the piston. (I realize you don't HAVE to pull the engine, but why not...)
3. Cost: Custom grind 8.5 C.R. J&E Pistons, only avail. in a set of 8: $899, discounted Felpro Wire-loc head gasket set: $129.99 discounted
So, now that I've ranted, raved, and carried on, does anyone care to give an opinion?
BTW, To talk boost in a Magnum engine, ask Bernd or Tom. To talk boost in a 4.7L, talk to Duner. Both have nicely modified turbo motors, both have experience with forced air induction. Good luck.
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Tom Slick
GenII
12/16/2002
21:31:34
| RE: Boost limits on 5.2 or 4.7
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It is more desirable to have the head gasket to fail rather than part of the motor... Why? It's cheaper to repalce the head gaskets...
Magnum engines should be able to handle about 8-9psi reliably... I would recommend better head gaskets... Fel-Pro, SCE, or Cometic... IF you're running much more boost than this, I recommend o-ringing the BLOCK (not the heads!!!) if your using the Fel-Pro or SCE's... The Cometics are fine without o-ringing, but I'd put a small receiver groove in the block if running over 11psi boost with them...
THe Mopar heads are more prone to blowing head gasket than some other engines due to the fact that they only have 4 head bolts per cylinder rather than 5.
Some people say to 0-ring the heads... DO NOT DO THIS... O-ring the block! O-ringing the heads became popular with some of the Ford engines, due to stress cracks caused from o-ringing the block... This is not the case for the Magnum engines... Plus, you don't have to re-O-ring the heads after having them resurfaced... O-ringing the heads may be easier if your just doung a head swap, but it is not the most reliable way to do it... If you have a choice, O-ring the block!!! Ron Jenkins of Magnum Force Race Car Fabrication and Bobby Kammer of Kammer Racing both agree that o-ringing the block is the proper way with Magnum engines.
Later!
Tom "Slick"
96 Dakota Sport 5.2 RC SB
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