Intake manifold modifications

[NoDOHC]

Update:

Decided to do dyno run on junk transmission as the entire test would be done in fourth gear (direct - no torque is transmitted through countershaft - doesn't need good countershaft bearings).

Unfortunately, when told that the engine turned 9,000 rpm and that the rear tires would be going 180ish MPH in fourth gear the dyno guy told me that a third gear run would be all I would get.

I was worried if the tranny would take it, but I figured we could always tow it home, so I let him run it in third.

I was very dissapointed with the output (186.9 WHP at 7200 rpm). I have a lot of tuning to do.

I learned that my gut feeling for ignition timing was not accurate as I started with 62 degrees BTDC at 9,000 with 13.8:1 AFR (gave 169 WHP at 8200).

Retarding the timing to 52 degrees BTDC at 9,000 gave me 182 WHP at 7100 rpm

Adding fuel to 13.2:1 gave 186 at 7200 rpm.

I think peak torque can be found at a more retarded ignition angle (as I was still increasing torque by retarding). I think peak torque is somewhere between 13.8 and 13.2AFR, but I will still try going a little richer. Peak torque (172 Wlb-ft) was made at 4800 rpm and it was running a little fat there (12.2:1).

Still hoping for 200 WHP as my high end is currently wasting fuel (>100% VE) and making no power. My spark plugs are filthy (too much premix) and will be replaced before the next dyno run.

More dyno runs later (the transmission is still alive!!)

On a side note, this is a Mustang Dyno and it has steady state loading, so I can actually tune real time (although I should get an electric fan to keep the engine cool during a steady state run at 8,000 rpm).

Comments/suggestions welcome (I will be renting the dyno for several hours this coming weekend, so I can try about anything).

[RotaryProphet]

Originally Posted by NoDOHC

Update:

I learned that my gut feeling for ignition timing was not accurate as I started with 62 degrees BTDC at 9,000 with 13.8:1 AFR (gave 169 WHP at 8200).

Retarding the timing to 52 degrees BTDC at 9,000 gave me 182 WHP at 7100 rpm

It's also really -really- far advanced from what I've heard of anyone running, even up at the redline. If you got 13WHP from retarding 10 degrees, I'd say you're way advanced. On an NA 13b, while on an engine dyno, I've never had to advance past 40, and that was a motor that was already on the down-slope of the VE curve. I seem to make pretty good power on most port configurations around 30+/-5 degrees BTDC.

Something to remember is that as you increase airflow to the chamber, you need less spark advance, not more. Retard your timing out towards the stock numbers, and you probably will hit 200whp

[drewski86]

Originally Posted by NoDOHC

(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)

Are you eventually going to turbo this motor?

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

It would be nice to know how much porting the manifolds really helped.

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?)

Peak acceleration should coincide with peak power.

Originally Posted by NoDOHC

186.9 WHP at 7200 rpm

See

I learned that my gut feeling for ignition timing was not accurate as I started with 62 degrees BTDC at 9,000 with 13.8:1 AFR (gave 169 WHP at 8200).

Retarding the timing to 52 degrees BTDC at 9,000 gave me 182 WHP at 7100 rpm

Something is wrong. You should be more around 25-30* BTDC. As far as you are advanced, you should be igniting on the compression stroke which will want to spin the motor backwards which is very bad. Hopefully your numbers are off somehow. I would make a pull at 25* and 13.1 AFR and see what happens. If you're way down on power than maybe your numbers are off but the motor is seeing the correct timing.

One more thing, you seem too focused on torque numbers. I don't know if this is because the g-tech only gives torque numbers but horsepower is what makes the car fast.

[vex]

Originally Posted by drewski86

One more thing, you seem too focused on torque numbers. I don't know if this is because the g-tech only gives torque numbers but horsepower is what makes the car fast.

That is a negative. The true meaning of HP is the application of Torque over time. This means that 1 HP = 550Ft-Lbs/sec.