Intake manifold modifications

NoDOHC · 07-27-2009, 06:25 PM

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).

07-27-2009, 06:25 PM	#5
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 17	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). __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)