427 Assembled

[zrss]

Originally Posted by Polo-1

703

Holy Smokes.......=D>

Hey Jim we are going to need a big NOS jet to keep up on the 402

Nope. Just leave the jet out and plumb straight from the NOS bottle into the plenum. We don't need no stinkin jets!

[Pete]

Originally Posted by zrss

Nope. Just leave the jet out and plumb straight from the NOS bottle into the plenum. We don't need no stinkin jets!

Or plumb it straight to the driver if you loose you'll have a good laugh.

Pete

[tomtom72]

Originally Posted by XfireZ51

Todd,

Do you think there any LT-5 CWs this motor either confirms or defies? If so, what are they?

Please, I'm lost on the "CW's" ..... "conventional wisdom's"? Thanks Dom.

Todd, I have a Q born of curiosity with respect to the extensive modifications to the combustion chambers and the cylinder head ports. Would any of those ideas be related to what the "next LT5" would have been if GM had chose the 4v/DOHC format over the LSx motor format?

I'm curious because Mr. McLellan said that they had a 4v/DOHC that would fit in a C5 chassis/body configuration, but it was a different motor than the LT5's that were used in the C4.

If you don't want to answer, I understand.


Tom

[Paul Workman]

Originally Posted by tomtom72

Please, I'm lost on the "CW's" ..... "conventional wisdom's"? Thanks Dom.

Tom

Cripes, Tom!! Where the hell were you when Dom was handing out his "My Oft Used But Seldom Understood Italian Acronyms" book!? Sheesh!

P.

[Polo-1]

Originally Posted by Pete

Or plumb it straight to the driver if you loose you'll have a good laugh.

Pete

Originally Posted by zrss

Nope. Just leave the jet out and plumb straight from the NOS bottle into the plenum. We don't need no stinkin jets!

No problem I can put a tee in the line... 1 for driver, 1 for motor
Motor should be good for 800hp,driver good for 800 feet

[tomtom72]

Originally Posted by Paul Workman

Cripes, Tom!! Where the hell were you when Dom was handing out his "My Oft Used But Seldom Understood Italian Acronyms" book!? Sheesh!

P.

Yea, I thought they said trains and I missed mine! That's okay, wait till I ask for the list of "CW's"......then Dom will send the black hand after me!

[XfireZ51]

Originally Posted by tomtom72

Yea, I thought they said trains and I missed mine! That's okay, wait till I ask for the list of "CW's"......then Dom will send the black hand after me!

There was a major bust yesterday in NY and NJ so I won't be able to access the registry from Sing Sing!

[tpepmeie]

Originally Posted by XfireZ51

Todd,

Do you think there any LT-5 CWs this motor either confirms or defies? If so, what are they?

I dont know, Dom. The motor did everything I designed it for. I wanted/expected peak power at 7k, and we pretty much got it. Based on the last couple pulls, I can say it peaks around 6900. My calculations say it is airflow and valve-lift limited at just over 700 hp, and thats what we saw. Could have ran the water temp way down in the 170's, leaned it out, and cranked in more spark advance. Maybe another 10hp in it? Hard to run 170 water on the street, though.

Everyone said the inlet ports were too small, yet it made real good power. The torque peak was about 400 rpm higher than I expected (5800), so that may tell that the exhaust cams were too long. The open chamber also had us concerned it might be more detonation prone than the tight quench design. Wasn't. We ran the usual spark advance, with just a spot around 5000 rpm of light knock retard (2d). Pretty standard result.

Interesting, at peak power, the manifold vaccum was about 1.0" Hg. I suspected the throttle body might be a little small, and I think that's confirmed. Maybe 10 hp there, with less vaccum? Cant go any bigger with the factory body, though. A bigger plenum volume might have crutched it some.

The cams really come in hard about 4000 rpm, and the fuel curve takes off at that point. Again, that profile is consistent with the VE curve I saw on the 1-d simulation. We really had a hard time giving it enough fuel up top.

So, no, I don't think it re-wrote basic engine theory or anything. 95% of the power we saw is due to the unique porting and camshafts as designed.

Todd

[XfireZ51]

"Everyone said the inlet ports were too small, yet it made real good power."

Good one.

"...unique porting and camshafts as designed."

Not sure you're giving yourself enough credit for pushing the envelope on lift/duration/overlap milestones.

"We really had a hard time giving it enough fuel up top."

Sounds like it was leaning out. Was bumping the secondary injector multiplier one of the ways you tried compensating? Be nice to have the electronic VariableFPR scheme the ZR1 has for something like this.
Or maybe slightly larger injectors with a change to the BPC. On the VE tables, I'm assuming you were topping out above 100% VE.

Should be interesting to see if the behavior changes much in a real world install.

Hats off!

[tpepmeie]

Originally Posted by XfireZ51

Was bumping the secondary injector multiplier one of the ways you tried compensating?

On the VE tables, I'm assuming you were topping out above 100% VE.

We got there in the end through the VE tables and injector size.

VE in the cal ended up way, way above 100%. 120's-130's in fact, to keep it nice and safe up there.