Stock high stall converter stall? 5.9 magnum
I see in the Dacco catolog there are low and high stall converters available. I have a 1987 904 lockup trans and converter and will be running it behind a 5.9 Magnum junkyard motor with a carb and air gap intake, recurved stock type distributor, 1 5/8 headers and a XE roller cam with 278/ 278 / 106 lobe seperation cam,that has 225degrees @.050 . lobes are 3344b Comp.
I would like input from anyone with experiance running a stock converter with a 5.9. I may chose to bracket race this setup and am not concerned about a great ET, just a consistant launch with 3.55 gears and 26 inch tall slicks, aprox 3200 race weight. The torque range of the cam is supposed to be from about 1800 rpm and up.
This is going to be a low budget deal, but at the low price of a replacement type converter, I would be willing to put one in, either in lockup or non lockup type by changing input shafts. What results have you had?
>Firstly a 278 roller cam with 225@050 ? That is a slower rate of lift from seat/seat to 050, than a FTH; what's up with that? Did you select that on purpose? and to what end?
>Secondly, installed 4* advanced, that cam will drop your Dcr to 6.75@128psi starting from an 8.2Scr base. that means a soggy bottom end. About 1.5 points soggy. So you need a hi-stall,period;with that cam.
>Rocco;post#2,recommends 2300. Which with your combo seems reasonable.
However since your rpm will be about 3000@ 65 with 3.55s and those little rollers, I would suggest a 2800.
>I would ditch that cam in a heartbeat, if I could find faster ramps. I have seen roller-cams with acceleration-ramps in the 30s. Then you can go up a size as to 050, and make more power. Or stick with 225* and make enough torque to pull a much lower stall, like Rocco's 2300.
>If that 5.9 is closer to 9.0Scr; then the Dcr might come in at 7.39@144, now only about 8/10ths of a point low.
For that cam to be a ripper, the Scr would need to be up 10/1 for a Dcr of 8.2@165psi. The 2300 will work very nice with this.
But in any case, the lo-stalls are out.
>Rocco also said
The advertised tq and hp specs of a cam mean jack..
And I couldn't agree more.
When applied to the powerband,I cannot imagine why they bother to write this drivel. It is as good as meaningless.
>To my way of thinking, the "powerband" starts at the torque peak and ends at the power peak. It is usually about 1400 to 1600 rpm wide and varies little in the realm of street cams. Now where it starts is governed mostly by the intake duration, and where it ends is governed mostly by the heads. Inside that realm the amount of power is governed mostly by the heads and the cam's lift.
>The seat to seat, to 050, mostly governs the sogginess down low, and gives us a reference to select a stall. It would be best to not have any degrees down there at all, but alas that is not possible. The roller cams come pretty close; but not yours apparently.
> And finally,with those 3.55s and a A998 automatic, you have the potential to trap at 95mph=6640rpm at the top of second gear. This is well outside the 225*s comfort zone. But to trap in Drive will be 95=4580 well below the power peak, and just above the torque peak. Have you thought of this?
This 225*cam will like 3.23s,and an engine with a lot more compression.
Or the next size bigger cam, with a lot less seat to seat.
Warning Opinion coming!lol
> If I had this combo; the 8.2Scr 5.9 engine, in a 3200 chassis, with the A998 tranny, then I would be looking at a 228* roller cam with no more than about a 262 advertised.This is what I would be looking for; 262/270/106. I would install it 100*.The ICA would be 51*. The Dcr might come in at 7.2@139psi. I would run this with 3.23s and a 2800TC.
The 3.23s will get you 6400 at the top of second=95mph. The 2800 will get you enough torque for a little tire-spin off the line. That tranny has a 1-2 split of 56%. The 228* cam will power-peak at about 5200 or a tad higher with good heads and that 106LSA, lets say 5400 max. This will require, with that tranny a shift rpm of about 6400 to drop in at 6400x 56%=3600, which is well out of the engines powerband which doesn't start til about 5400less 1400=4000rpm.PHEW!,long sentence there. Anyway that is what I would do
If I had to keep the that 225* cam,the 3.55s and the A998, I would bump up the compression to at least 10/1.
If you have to shift into Drive before the trap, the car will slow down.