Let me start over a bit , the car is an unfinished project that i recently purchased . The PO rebuilt the motor and had a 727 transmission built and then installed everything . I only have basic info on the motor build . Nothing was plumbed so I got everything done so I could break in the cam and just check the general health of the motor . As far as gears the car has a bone stock 8 1/4 . What I see in the future is no more than 3:91 gears and really leaning towards 3:55 if I can make them work and 15" wheels . Primary use will be street /cruise with occasional track time .
This is seriously messed up. There are only 3 cures;
1)lots more compression; more static and more dynamic
2)lots more compression; more static and more dynamic
3)lots more compression; more static and more dynamic
After that maybe you get to keep that 2800,etc,
BTW, what
nm9 said is bang-on. A Dcr in the high 6s puts
your VP down under 71, living among weak 6 bangers, and 4s.
Hi-performance starts at around 160. Modest around
140, lowly around 120,sucks pretty bad at 100, Wish I had never been born at under 90,lol.
Now; you can get your teener wound up tight and show pretty good, but getting going will be almost embarrassing, until your TC and gears are so big, the car become a track only car.
Your #1 priority is to start over with hi-compression pistons. And #2 is to get a more street-friendly cam.
Here's a fun recipe; 10/0 Scr and a 268* cam. The Dcr works out to about 8.2@165psi and a VP of
128. So you are between Modest and Lowly.
Or here's another, geared more to a DD; an Scr of 9.5 with a 256* cam puts your Dcr at 8.2@165psi and a VP of
134, so you're bottom end is waking up.
Or if you want to blow some Mustangs away; How about a 4"stroker kit and keep the 292* cam; You will need a 4" arm and an Scr of 10.9 to get a Dcr of 8.2@165psi and a VP of
141. Now your 388cuber is rocking.
For comparison, here's a 416 cuber at 10.0 and a 272* cam. The Dcr comes in at 8.2@165psi with a VP of
166
Notice I kept the Dcr and cylinder pressure street and iron head friendly, and as good as identical,so;all of these should run on pumpgas.
Ok one more; the stock original engine with the stock 240* cam, and an Scr of
8.0, will get you a Dcr of 7.0@135psi, and a VP of
113; that's pretty close to lowly! Yet light years ahead of 71
Notice the cylinder pressure is pretty good. Notice also that the VP is pretty low. The VP gives us an idea of how the engine will perform in day to day useage.
You can read about it here;
V/P Index Calculation
The more cylinder pressure your engine makes, generally the more driveable it will be, ie more pressure takes off harder. This makes the TC and gear requirements easier to target. But there is a limit to how much pressure you can run and that is detonation. This must be avoided at all costs. 165psi is about the limit for iron heads and pump gas.
Dcr is a snapshot of how performance oriented the engine is, and is especially keen at determining what octane rating you will need. As always the higher the better, with 8.2 being about the limit for pump gas/iron.
With your stated useage, you don't really have to push the envelope. And with open-chamber heads, I recommend you don't.
Re-formatting your engine, the Scr,Dcr,and cam selection should be a carefully orchestrated endeavor. Those guys all have to play nice together.To do otherwise is to risk the combo you now have. But hey, you have no place to go but better!
Here's what an original 225 looks like;
Static compression ratio of 8.2:1, Dcr of 7.25@141psi, and a VP of
82..
82 is bigger than 71,lol
Although he is a pretty smart dude when it comes to Mopars and cams!!
