Only 460hp

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Only 460 hp, I know how you feel. 73 Duster, 3680 lbs, 380 hp crate motor, high stall converter etc only goes 9s in the 1/8. Careful planning = Piece of garbage
 
srduster340 said:
More compression is definitely in the plans. How much more cam do I need? I've read that strokers eat duration. Right now I'm at 242/250. Do I need 248/254 or 250/256?
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I would base the cam specs on what CR you’re thinking, Fuel used. (I assume pump premium) Max rpm as well as Rpm drop each gear change etc. I’d roughly guess something in the low 250°‘[email protected]” or so. With those 3.55 gears requires some thought. There are a lot of members here who are very well versed on what would be needed.
 
Ported Mopar iron heads #P4876179 275@650 (
advertised)
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In my 2000 MP catalog it shows the …179 heads ported for lifts up to 0.500”

Could these heads not flow as suspected?

From a post by Rob C on Moparts…

The first 2 heads are the 360 heads. It is stated that they are ported to a 44% increase over stock heads which flow 200 cfm at least if not a tiny bit better. So, at least an addional 88 cfm makes them a pretty good flowing head. 288cfm should be able to get you moving well. Produced before Edelbrock came about?
Each price is per head. (1 head complete.)

All prices are the Racers Net list in the year 2000.

For the P4876179, 2.02-1.60 ported for .500 lift, $1206.60.
For the P4876180. 2.02-1.60, ported for .650 lift, $995.00.
-----------P5249459, 360HP- 1.88-1.60 (1 Stock head complete) $495
-----------P5007089, W2 head assembly, unported, $862
-----------P5007047 STAGE V, 500/505 service head, $867
-----------P5249112 STABE V ported/2.14-1.81 (15% flow increase) $1295
-----------P4876186 Stage VI non CNC ported heads with 2.14-1.81 $1375.
-----------P5876187, Stage VI non CNC ported head, 2.18-1.81, $1935
-----------P4876857, HEMI, $1495. Not ported, just an assembled head.
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my 2000 MP catalog

image.jpg
 
This is a street car with 3.55 gears, manual transmission. Not after maximum high rpm power.
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I didn’t catch this first time around........

In light of that info I’d say.......install as is and see how it goes.
 
12many said:
I find it kinda sad when someone puts together a new combo and hits the dyno and ends up dejected with the results. See it here often. Then they immediately start thinking about changing out internals, never seeing what they’ve got after some time working on it.

I’d leave it as is, take it to the track and work on launches, hooking and shift points. See what you’ve got there as a package. The ability to put down good numbers at the track is more impressive than some arbitrary horsepower number IMO. 460, 500 hp on the street means nothing other than a number to throw out to impress.
But as it is the CR is kinda low, you could step up a bit on cam, intake, rear gear.
But you have the combo, you say you’re happy with it so work with it for the coming year, see whatcha got on the street and track
Then later maybe go with a 4.10 swap, try a nicely ported single plane intake.
You can always change those internals later as well.
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Like PRH said, he needs to figure out WHY it’s that low. He needs to post fuel flow numbers if he has them.

Its making 1.23 TQ/CID and 1.11 HP/CID. That’s weak.

It’s clearly out of air. And it makes my point about jamming all that stroke in there and not being able to feed it.

And it’s all done by 5300. A perfect example of way too much stoke and no way to feed it.

He can stuff more cam in it, but if the heads have the cross section to flow 270 he has other issues.
 
If the Mopar Performance heads are optimally ported for only .500" lift, there's a good chance that the valve springs that came with them are nowhere near what they need to be pressure-wize and you could be floating the valves, not to mention possibly having guide clearance issues and/or not enough installed height for the lift. Check for signs of damage.

Just my opinion, but for a street car:

* Get a 750 Holley DP carb & tune. Should be easier to tune and provide more air velocity/throttle response.

* SIR rods are rated for 500hp, which you're already shooting for. I figure the 4 speed and long stroke will be stressing the rods even more. Even less trust with nitrous. I'd suggest the Scat I-beams (A little bit heavier.) or H-beam rods even without nitrous.

* 1.5 rockers should be plenty.

* Is the cam installed/degreed properly.

* More compression will make a noticeable difference, if available gas can handle it
 
I posted the incorrect part # for the heads. I definitely have the P4876180's. Valve springs were changed to Comp springs. I'm not chasing ET's. The car hasn't been on the track and may never.
 
I agree the OP's results seem fairly reasonable for the heads and cam combo. As others have said, more CR, more cam, and more head flow are in order if you want more output. I don't know about the step headers. Others may have better Intel on them.

Me? I'm a big fan of a SFT cam. My 408 has a 251/[email protected] SFT. If I had to do it again, I'd go a skosh bigger - maybe something like a [email protected]. It's pretty rough at idle (my wife loves it!) but still idles at about 850-900 and as Rat Bastid said, the 4" stroke can handle cam duration! My engine made 503 #-ft @ 3500 rpm and that's the only point that was recorded as after that, the et slip will tell you what you need to know. (We spotted it in at higher RPM's with other engines tested on the same dyno with similar parts so have a good estimate what it makes. But the et slip is a better indicator for me.

I have a thread called The 72 Demon Follies if you want to see more details on the combo but the car has gone a best of [email protected] .

I'll keep tuning on it but I am limited by the Eddie RPM heads and then the cam. I suspect your engine is too. Anyhow, I share just so you can see what someone else has done. Learn from it and do better!!
 
Demonx2 said:
I agree the OP's results seem fairly reasonable for the heads and cam combo. As others have said, more CR, more cam, and more head flow are in order if you want more output. I don't know about the step headers. Others may have better Intel on them.

Me? I'm a big fan of a SFT cam. My 408 has a 251/[email protected] SFT. If I had to do it again, I'd go a skosh bigger - maybe something like a [email protected]. It's pretty rough at idle (my wife loves it!) but still idles at about 850-900 and as Rat Bastid said, the 4" stroke can handle cam duration! My engine made 503 #-ft @ 3500 rpm and that's the only point that was recorded as after that, the et slip will tell you what you need to know. (We spotted it in at higher RPM's with other engines tested on the same dyno with similar parts so have a good estimate what it makes. But the et slip is a better indicator for me.

I have a thread called The 72 Demon Follies if you want to see more details on the combo but the car has gone a best of [email protected] .

I'll keep tuning on it but I am limited by the Eddie RPM heads and then the cam. I suspect your engine is too. Anyhow, I share just so you can see what someone else has done. Learn from it and do better!!
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Thanks. I'll check that out.
 
In a street car with 3.55 gears, I’d drive it and be grinning like a mule eating sawbriars.
 
the headers are too small, need 1 3/4 to 1 7/8 stepped headers on my 340, stocker i run 1 7/8 headers, friend of mine had 1 5/8 to 1 3/4 step headers on his 340, changed to 1 7/8 picked up 35 hp. just food for thought,
 
srduster340 said:
I'm not chasing ET's. The car hasn't been on the track and may never.
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Put it in the car, drive it and have fun...

Your statement says it all. You aren't chasing et. Other than bragging about hp, the rest of this exercise means nothing in the big picture.

It's also fat according to the sheet... could be 20hp right there. Work on the carb a bit, maybe take a jet size or two out of each end.
 
I guess it really depends on what you're after. There's 100 HP on the table with ported heads, suitably sized cam, and a proper intake. You could probably get there without changing the bottom end but yeah 9 compression is pretty lowish.

However it's a good number for a centrifugal supercharger or a turbo. Food for thought.
 
ou812 said:
If you leave it alone, I'd move to a 750 cfm proform or holley or quick fuel carb...it will drive much better and possibly pick up power.
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That's sacrilege!!!! Everybody knows a bigger carb will make more power......:rofl:
 
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