Importance of a proper tune.

[Fast305]

Just want to show you'll how important a proper tune can be, especially when working with a OBDI vehicle running speed density. This is a TPI Vortec 305 built up some, but none the less, I picked up over 30 RWHP from fine tweaking on the dyno. I started out at 322 RWHP @ 4,700 from tuning without the dyno. My biggest power gain surprisingly was changing the WOT air/fuel ratio from the mid 12 down to 11.6:1. E10 does some weird things to the Air Fuel Ratio and engine wants. WOT TCC lockup was worth 9 HP, but I lost 8 ft/lbs in the process. Messing with the timing resulted in power loss, so I left it the way I had it.

[jim_in_dorris]

Wow! As usual, very impressive results for a 305. Just curious, which lower intake do you have mated up to the vortec heads to allow TPI?

[Fast305]

Originally Posted by jim_in_dorris

Wow! As usual, very impressive results for a 305. Just curious, which lower intake do you have mated up to the vortec heads to allow TPI?

I have one of the ones that SDC chevy sold a while back. I believe it was cast by edelbrock before they started casting their own.

[oldred95]

Pretty diligent but its no 4.8 liter.

thats damn stout for the lil engine! interesting about TCC lockup... the dyno really is a nice tool for fine tuning/finalizing things... especially when you are at optimal performance that the engine can make.

[oldred95]

FWIW I've noticed the same thing with my converter. Stock it commands torque converter clutch lockup at 75 mph at WOT. When mine locks it drops the rpms by about 3-400 and it actually accelerates faster. If you have a good converter I imagine the effect would be the opposite but mines a loose slopping pile of crap.

[MSlewis]

Excellent torqueband & impressive peak numbers. Looks like if you had a little more time with the dyno you could get rid of those AFR fluctuations as well. Makes sense having to lower the ratio for the ethanol. Curious, what size valves are you running in those heads?

BTW, what gear were you pulling these runs on & did you have the converter locked up from the start? If not when did you engage it?

[1BadZ71Tahoe]

Originally Posted by MSlewis

Excellent torqueband & impressive peak numbers. Looks like if you had a little more time with the dyno you could get rid of those AFR fluctuations as well. Makes sense having to lower the ratio for the ethanol. Curious, what size valves are you running in those heads?

BTW, what gear were you pulling these runs on & did you have the converter locked up from the start? If not when did you engage it?

Werd on the size valves in the heads.

[1500chevy5.7l]

ya how do you have yours to do that do you jsut set the force tcc lock ..to lovk the converter from the get go like really low mph...or what do you do?

[Gran Patron]

Crap, that's some pretty fine darn numbers for a 305.

[oldred95]

They are CNC ported 305 vortec castings with 1.94 intake valves and 1.6 exhaust.

[Fast305]

So I have done some more tuning to the van. Worked with the AE and timing as well as the PE AFR. I was also recently making some datalogs. I decided it was time to enable the speed limiter on it after this datalog. If it actually reached this speed, it might not have taken it long to get there, but we have NO interest in going this fast on a public road in the name of safety, even though it MIGHT have been 1:00 AM.