4.8L Project Horsepower - One step at a time

[George C]

Yep...and yours being a 4WD and a different year it prolly has more. Is yours an X or a W?

you tell me. my old 00 s10 extcab 4x4
blazer is 99

i think your right 2wd was 180 and 4wd was 190 but seriously what is the difference

[farmtruc]

Dyno'd new cam.

I don't have time right now to post graph, but I will later.

Cam Specs: 220/220 - .581-.581-112+4

This going through stock manifolds, cats and exhaust system.

Made 270hp, which is +24hp over previous mods/tune.

The truck liked 13.2 a/f ratio on this run.

[Slimsilverado]

Can you explain for my ignorant self how a 3600 stall would loose HP but effectivly increase the ET. I know having the higher Stall helps get it outta the hole because of the RPM difference. Is it because the verter is slippin? help me understand please...

[farmtruc]

Can ... Is it because the verter is slippin? help me understand please...

Yes. Not much but it is.
Lock it up and you'll see an increase in HP.

I'll do some dyno runs with it locked and unlocked to show the difference.

[Slimsilverado]

Sweet whats the difference between locked and unlocked? I notice on mine Nelson tune with my 3k stall in 1-3 it will flash if you at a low rpm up to 3k but in OD 4th it does not do that...

[GasGuzzler]

That's the diff between the T/C clutch locked or not...the tune being locked is another thing all together...

[Slimsilverado]

so if its locked then the stall is defeated meaning its fully engaged all the time. Dammit Nathan dont leave me hangin...

[farmtruc]

Think of a stall converter this way:

You have two box fans facing one another. The two fans are acting like the torque converter.
One fan is connected to the engine and one to the transmission.
Turn on one fan and you'll obviously notice, the second fan doesn't turn as fast right away.
As the first fan is sped up, the second one will eventually equal the speed of the first fan. (just assume it will for this explanation).
As you change the first fans speed from low to high (immitating the throttle), there is a delay when comparing the both fans. This is how a stall converter acts when you play with the throttle.
Stall speed is determined by many factors, but internally to the converter, the fins are angled to adjust stall speed. If the converter has a flatter fan blade pitch, the higher the stall.
Now, for lockup. Put a stick through both fans, note they turn the same speed and are considered locked up.
Some clutches and tunes lock up harder than others, so this is more noticable in some setups.

With your tune specifically, I didn't allow the converter to lockup 1-3 gears. Actually, if you look at the mph for lockup, they really don't lock up anway with a stock tune, unless you hold each gear.
Yours only locks up in fourth with light throttle around 40-50mph.

hope this helps,
allen

[PurpleMinivan]

hope this helps,
allen

If he still doesn't get it after that explanation... he never will

Stall converter sticky!

[Slimsilverado]

Thanks Allen... F U KURT :flipoff: just wondering i get the basic concept just wondering about the tune n ish and why would you loose some power with a higher stall but i got ya...