Dartswinger70
Well-Known Member
All people on the internet want to do is argue ...
318 build #2 "cost minded" for the '74 Duster
- Thread starter 318willrun
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2.94 gears can actually start to make up time as MPH vs RPM in the quarter.
That was my experience on the street with my poly 318 '66 Coronet racing against predominately gm 350 powered cars with the common 3.08 factory gear.
Not a lot of difference between 3.08 and 2.94, but I'd gain a little on the top end around 70-ish MPH.
That was my experience on the street with my poly 318 '66 Coronet racing against predominately gm 350 powered cars with the common 3.08 factory gear.
Not a lot of difference between 3.08 and 2.94, but I'd gain a little on the top end around 70-ish MPH.
j par
Well-hung Member
HEY!!!... Everybody's known for 10 years now that I've had the slowest stroker on the internet and I'm not letting that title getting taken away from me!!... His car may be slow but mine's the slowest damn it....
Also it's very well known that I'm an internet supermodel....
...Sorry I had to draw the line somewhere....
j par
Well-hung Member
When you're trying to take my title away I'm going to the mat...All people on the internet want to do is argue ...
Sounds like a current day "doubting Thomas"!
That 2.94 was actually a pretty good street gear. Not as much of a dog off the line as 2.76, and that slight top end "walk" came in at just the right time.
My poly 318 was way torquey, and did great off the line. Easily made up for the difference in 2.94 vs 3.08.
If you were one of my victims and got jumped by a fender or almost a fender off the line, then kept even or maybe gained that fender back, but at 70, started getting walked you pretty much knew going on was a lost cause.
Any faster than 80-ish MPH on the roads I was on was asking for trouble, and most of the cars I raced were built street cars kinda in the same boat.
Surprising 350 guys with a 318 was a super bonus.
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Not trying to be a smart arse, but something is wrong with the combo. A bone stock 5.2 magnum in an early body style dakota is quicker than that.
Not piling on, but I ran a '92 club cab Dakota with the 3.9 V6 automatic stone-factory-stock and went low 17's. But I think he understands his combo didn't perform well.
Yeah club cab with 5.2 is in the 15's in the 1/4.
Maybe you already mentioned it and I overlooked it, have you run the 1/4 and done mileage testing with the combo that is in the Duster now?
Ran the 1/4, went high 14's but not with the dual quads, it was with the singe 4bbl. I've not checked mpg.
DionR
Well-Known Member
I think that manifold/header test is flawed. I base it on the fact that Holdener on YT tested a 300hp Crate Motor with the dual plane M1 intake against a JY 5.9 with a beer barrel intake and got virtually the same numbers. If dropping that extreme runner length intake won't pick up power, I don't think much will.
My opinion is that the real restriction on that motor is the cam, and until a better cam is swapped in the real advantage to the manifolds and/or headers isn't going to show itself. Not saying there weren't advantages shown, just that it was less than what it would have been if the exhaust had been the restriction.
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when you add a 200 shot it will matter the question is how much prolly alot more then what they found na
hopefully soon i can say with my own build soon
my 318 from the early 80s picked up quite abit with headers as compared to manifolds and helped mpg
340 manifolds not so much on a mild engine
both those engines you quote have low compression as well
my 340 is a legit 9.99 comp ratio and a 8.3 dcr with a 218@50 454 lift 110 lsa ica 60 in at 106 it has a 68 340 drivers side and the jeep 2 1/8 pass side with a 3.91sg and a 650 dp it will smoke the tires all the way thru 2nd if i choose great street cam on 93 octane much more low end then the stock 340 cam
DionR
Well-Known Member
Just saying that pointing to that test and saying the HP manifolds or headers are worth only ___ hp is flawed. Put something better than the broomstick cam it came with in and make the exhaust the restriction and (I think) the differences will be greater. Which means the magazine test is useless when applied to something other than a 300hp crate motor beyond the generalizations that tube is better than cast iron.
have seen test on 340s with a cam etc they lose 15 20 hp over headers up top
clearly they will loose more as power goes up
60 to 80 on a stroker dyno i watched
all i said is id like to see the difference on that motor with a twin stage shot of spray
might matter less with a mild build if so its another way for a lower cost motor to get good power
DionR
Well-Known Member
True but it still helpful, it's not like all of a sudden there's gonna be 20-30 hp between manifolds, not to many are gonna try to run manifolds on a 400 hp plus engine, a 350 hp test engine would of been better.
To me the test shows no point spending money on 340 manifolds for power gains any 360/5.9l are good enough. And if you already got a good dual exhaust with 318 manifolds not really worth the swap either.
DionR
Well-Known Member
No argument. But I too often see this test used to say that 340 manifolds are only worth 4 hp and I think that is bunk. The only data there is that with the small cam motor in the test, the HP manifolds aren't worth much. Anything beyond that is a guess.
It's kind of like swapping a big cam under a 2bbl intake and then saying the cam wasn't worth much. The cam stopped being the choke point and its true potential can't be evaluated until the other choke points are removed.
A similar motor to the one the in the test made 50+ more hp with a swap to a small cam, peak to peak. And it made 70+ more hp where the new cam peaked. Hard to say what the HP manifolds would see at that 5200 peak if compared.
The 300hp crate motor doesn't have lobes on the cam and using this test to validate any of the parts really can't go beyond saying "this is better than that". Any use of quantitative data (eg. 4 hp more) is suspect. In my opinion.
See above, this is exactly my concern with holding this test up as "proof". I just can't see using the linked test to say 340 manifolds aren't worth something on a motor with a real cam. The data just isn't there to say one way or the other. I understand that they might not be much better, I'm just saying this test can't be used to show it is so.
None of this helps the OP though. That test doesn't say anything about the Magnum manifolds and how they compare so it's not worth polluting this thread with beyond what has already been said.
I can add that Holdener did a test with the small outlet Magnum exhaust manifolds compared to the big outlet ones, and I think the big outlet manifolds were worth like 5 hp at the peak. So, compared to the referenced exhaust test, the big outlet manifolds might be worth about the same as the 340 HP manifolds. But that's just a guess.
If I was to run a real cam one with a good amount of overlap to me long tube headers are mandatory to work with the overlap. With cams with a moderate or lesser amount of overlap I highly doubt there's a huge difference between manifolds but guess we won't know until someone does a test. But looking how shorty headers dyno poorly compared to long tube headers to me it's got to do more with tube length and collector size than restriction.
This is the same thing as above comparing a small to a larger cam swap under a two barrel carb on a OEM iron intake. If the header being tested is on a weak engine like the 300/360 crate engine, the header really doesn’t shine. It looks like crap. IMO, the only time a shorty should be used is ether in a Happy Days hot rod or powering a turbo. Otherwise there garbage.
That 300/360 is a production engine with a M1 dual plane and 750 carb with 1-3/4 headers. When MP changed the parts for the 380/360, it was intake cam and IIRC, larger headers.
We've chosen an intake for the 5.2. Weiand Stealth 8022
Ok, so I'll do a quick parts list so far. 8 pages can be hard to find the build pieces.
* '94 5.2 magnum engine
* 20-745-9 Comp Cam Roller
* Hughes Spring Kit with 1110 springs (springs/locks/retainers)
* Weiand Stealth Intake 8022
* '94 5.2 magnum engine
* 20-745-9 Comp Cam Roller
* Hughes Spring Kit with 1110 springs (springs/locks/retainers)
* Weiand Stealth Intake 8022
DionR
Well-Known Member
What's your plan for bolting the intake to the heads? Re-drill the Magnums? EQ heads with the LA bolt pattern?
Sorry if I missed it earlier.
You didn't miss it. We have a couple options, some which you mentioned, or the use of LA heads
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