Quench, separated thread. - Page 3 - Motorgen - Automotive Events, Meets, Cruises and Forums

enkeivette · 10-07-2009, 06:02 PM

Going to theorize.

If quench is just basically a matter of mixing the air and gas and moving it all around evenly on top of the cylinder before combustion to promote even combustion (thereby eliminating hot spots, or spots more prone to detonation) then it wouldn't matter with a blower. Blowers mix the air and gas and move the air all around in the cylinder before the 'quench' happens. (Pushing the air in, rather than drawing it in) So with blower motors, there should be practically no hot spots.

With the same line of reasoning, on FI cars, expecially those of a relly good design like the LS engines, it shouldn't matter as much because the fuel and air would be mixed better than in a carb app. Not saying it's the same as a blower motor, just better than carb motors.

BADDASSC6 · 10-07-2009, 06:39 PM

I read the quench post it was really good, but my interpretation was that they were discussing setting quench with the correct compression ratio. I'm not saying it's not important, but I will say that it's not as important as correcting the CR.
my $.02

enkeivette · 10-07-2009, 07:44 PM

Quote:

Originally Posted by BRUTAL64

So, look at it this way. A pro builder is looking at much higher rpms than the average Joe. My 400 is set up with .054 quench--cause I was always spinning them over 7000 rpm. So rod material, rpm and piston clearance set the final closest quench spec.

So a low rpm engine with close piston clearances could go .035 quench with a steel forged rod.

Is this 7k 400 in your Vette? It's not the one with balance issues is it? Cuz I really want to feel what a 7K rpm SBC is all about. Mine has some expensive parts and even it chokes out at 6K.

94cobra69ss396 · 10-07-2009, 09:11 PM

Quote:

Originally Posted by enkeivette

Is this 7k 400 in your Vette? It's not the one with balance issues is it? Cuz I really want to feel what a 7K rpm SBC is all about. Mine has some expensive parts and even it chokes out at 6K.

Your engine shouldn't choke at 6000. I run the 454 in the Chevelle to 6500 and I have about the same size cam as you do 246 @.050 with a .623 lift with a longer stroke. You may not have enough valve spring pressure if it's choking at 6000. That's what happened to me with the old valve springs on the 454. They were the stock Edelbrock ones that are for a flat tappet cam and I'm running a solid roller. Since I only run it to 6500 they had enough pressure for a couple years but then the car started to choke past 6000. I haven't run it down the track yet to see how it pulls but I jumped on it in second gear with the new springs and with the tires blazin I quickly shifted it to third when the tack hit 6800.

enkeivette · 10-07-2009, 09:19 PM

Quote:

Originally Posted by 94cobra69ss396

Your engine shouldn't choke at 6000. I run the 454 in the Chevelle to 6500 and I have about the same size cam as you do 246 @.050 with a .623 lift with a longer stock. You may not have enough valve spring pressure if it's choking at 6000. That's what happened to me with the old valve springs on the 454. They were the stock Edelbrock ones that are for a flat tappet cam and I'm running a solid roller. Since I only run it to 6500 they had enough pressure for a couple years but then the car started to choke past 6000. I haven't run it down the track yet to see how it pulls but I jumped on it in second gear with the new springs and with the tires blazin I quickly shifted it to third when the tack hit 6800.

Hmmm... I got the upgraded springs from AFR (heavier) not sure what rate they are. I do have 1 5/8ths headers and catalytic converters though. Could this have anything to do with it?

I think the motor made peak hp at 6.1K

It feels like it pulls hard past 6K now, but it's so damn powerful it's hard to tell when it chokes out. I remember it choked after 6K when NA so that's where I shift now to be safe. To be honest I could be shifting at 5.5K one time and 6.5K the next, like I said, and I'm sure you empathize, the rpm moves up quicker than my senses can follow. Or you might have more time to react with a wider gear set (3 speed auto right?)

enkeivette · 10-07-2009, 09:26 PM

Also, don't forget that my cam is a hyd roller. Heavy as they come.

94cobra69ss396 · 10-07-2009, 09:43 PM

Quote:

Originally Posted by enkeivette

Hmmm... I got the upgraded springs from AFR (heavier) not sure what rate they are. I do have 1 5/8ths headers and catalytic converters though. Could this have anything to do with it?

I think the motor made peak hp at 6.1K

It feels like it pulls hard past 6K now, but it's so damn powerful it's hard to tell when it chokes out. I remember it choked after 6K when NA so that's where I shift now to be safe. To be honest I could be shifting at 5.5K one time and 6.5K the next, like I said, and I'm sure you empathize, the rpm moves up quicker than my senses can follow. Or you might have more time to react with a wider gear set (3 speed auto right?)

I was in second gear (1.48) and you're correct that it goes quick. I just caught the tack as I was shifting. When I drag race the car and this goes for the Cobra as well I shift from first to second by the sound of the engine. I don't even look at the tack until I'm shifting from second to third and from third to fourth on the Cobra. So I completely understand. Also, I'm kind of out in the middle of no where so I was on a deserted street going straight.

If you're going off what your car was doing before when it was lean then that would make sense.

enkeivette · 10-07-2009, 09:45 PM

Quote:

Originally Posted by 94cobra69ss396

If you're going off what your car was doing before when it was lean then that would make sense.

Sarcasm?

94cobra69ss396 · 10-08-2009, 08:42 AM

Quote:

Originally Posted by enkeivette

Sarcasm?

No. Your car wouldn't make power up in the higher rpms due to it running lean so it would feel like it was running flat. If you are still feeling this now that the AFR is correct then I'd say you don't have enough valve spring pressure.

BRUTAL64 · 10-08-2009, 10:30 AM

Quote:

Originally Posted by enkeivette

Is this 7k 400 in your Vette? It's not the one with balance issues is it? Cuz I really want to feel what a 7K rpm SBC is all about. Mine has some expensive parts and even it chokes out at 6K.

Yes, It was suppost to be a 7,000 rpm motor, BUT, that damn vibration it has limits my big rpm blasts. The 12 dollar motor went to 7,000 -all the way around my dash tach- anytime I wanted. I balanced that motor with a UPS scale.

I should have balanced this motor myself.

I once rode in a 69 Z28 that would spin over .........ready........8,000 rpm. I didn't believe it either till I rode in it. Yep, quite the sound. Nascar tone to it.