[NoDOHC]

Ok, Vex has me thinking about this intake manifold thing now.

I have always been told that the RE Intake manifolds flowed the best. Not having access to a RE manifold, but having access to many Turbo II manifolds, I decided that i would make do with what I had.

After increasing the runner cross-sectional area from 2.32 in2 to 3.20 in2 (a lot of die grinding), giving the engine a mild street port (more die grinding), polishing the runners to 400 grit where dry and 80 grit where wet, measuring the entire runner length to maintain a uniform cross-sectional area in the manifold (don't ask how many times I broke through), modifying the plenum to fill all irregularities and smooth the air path, and porting and polishing the throttle bodies, I have encounted some odd engine characteristics.

(I polished the rotor faces to 1000 grit, but I doubt that had any effect on the power.) I am using stock S4 8.5:1 rotors (ground down to about 8.2:1)

I have yet to get on a real dyno, so I will not post numbers here except for AFR and VE (which I can compute) and relative torque (from the g-tech).

The VE for this engine is above 100% from 3000 rpm to 8500 rpm (9000 rpm rev limiter). I promised myself that I would stop at 8500rpm, but I couldn't cut an engine off that was pulling that hard. Unfortunately, my peak VE (108% at 6500rpm) is disappointing for me (I had hoped for 112% at 7000rpm).

The rev limiter is very annoying at 9,000 rpm because it is still pulling strong. (My legs are too important to me to rev it higher, my clutch is rated for 9500).

At 13.2:1 AFR, I can't keep my Bridgestone HP50s hooked up above 3500 rpm in first gear (with a gentle launch).

My first question: Would anyone find it beneficial if I strapped a stock TII manifold on the engine to see how much it kills the VE?

My second question: Why does my G-tech show the peak acceleration at 7500 rpm when the peak VE is at 6500 rpm? (Is there something I am missing, shouldn't peak torque and peak VE coincide?)

Is this a transient issue? Maybe the g-tech assumes a road load that is incorrect.

VE curve (based on injected quantity, injector size, fuel pressure and AFR as measured on the wideband):
rpm 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000
VE 67% 75% 78% 85% 95% 100%103% 103% 103% 104% 106% 106% 108% 107% 104% 101% 100% 94%
Torque curve: (Please do not set store by this, g-tech numbers assuming 3000 pound car weight, up to 10% high)
rpm 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000
lb-ft 130, 135, 145, 148, 152, 155, 156, 158, 158, 160, 163, 165, 160, 152, 140

For comparison:
NA 6-port, sleeves opened at 5000rpm, Stock intake manifold, secondary throttle plate mod.
rpm 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 7500
VE 75%, 80%, 83%, 89%, 91%, 95%, 93%, 89%, 82%
lb-ft 120, 123, 125, 128, 132, 135, 135, 128, 120
(made about 155 WHp with 196,000 miles)

I really need to make a real dyno run (I am actually excited because I think I can break 200 WHp.)

Also: What AFR do you guys typically run on a NA rotary? This thing LOVES fuel. Seems to make peak torque at 12.2:1 (my 6-port, 9.4:1 engine made peak torque at 13.5:1 AFR).

I have heard 26 degrees is optimal ignition timing, is this true for NA? I get best torque at 44 degrees BTDC at 9000.

Any thoughts are welcome.