Blowing thru the converter?

[stroker1]

How can I tell exactly if I am blowing thru my converter? I have recently started hitting the rev limiter as my truck has sped up. I'm only turning 6800-7000 at the traps but before I was turning about 6400. I'm spraying a 180 shot but that is really no different except I've leaned it down some. I'm running 1/8th mile only. It's a 8" converter TCI, that's been restalled and changed to spragless. It has a top cut aluminum stator and was built by Atlantic Coast Converters in Conway, SC. I know these guys stand behind their stuff and are great to work with. But just wanted to get a good opinion before calling. I have a 2950 lb S10 truck with a 383 small block, 13.3:1 compression, small 170cc aluminum heads, 4.56 gears, and no nitrous cam at 106 lsa 256/268@.050" .640/.640 lift w/1.6 rockers. I'm foot braking, 28x10.5" tire, 9" with 4.56 gears, 1.82 glide, average of 1.43 60ft, 1/8th mile 6.32 @108 mph and about 6800 rpms. Could also be bouncing the window switch for the nitrous.

Thanks for the help. Stroker1

[John_Heard]

Doesn't really sound like it's blowing through it as you say it's speed up. How much faster is it going MPH wise / ET when it's running the additional 400-600 rpm more? That's when you're spraying it right?

No sprag is probably costing you a little bit of ET/MPH as well.

[stroker1]

It's about 107.7-108.2 on a 6.50 pass or a 6.30 pass. They are the same mph just lower ET.

Off The Wall Pass-Could Have Been Surging
1.45 60ft.
6.50 ET
107.7 mph

Typical Pass
1.43 60ft.
6.31 ET
108.42 mph
RPMs at trap sometimes have been 6400, sometimes have been 6800.

Best Ever
1.40 60ft.
6.27 ET
108.42 mph
RPMs at trap about 6600???????WTF

Thanks for the reply John.

[John_Heard]

How are you recording your trap speed RPM? Data logger, recording tach or are you doing that by Memory watching the tach/shift light? Yes, that is kinda weird that the MPH has been holding about the same but ET is better. I'd be real tempted to blame it on the lack of a sprag, especially if it seems to be hitting a brick wall right about that RPM level you're going through the traps at.

[stroker1]

I just checked my window switch and it is set to cut off at 6800 and the upper rev limiter is set at 7000. So I'm wondering if I need to raise the rev limiter and/or the window switch? Ya think that might be where the RPM fluctuation is coming from? Maybe the nitrous is cutting off and on about the same time it goes thru the traps?

Long term, I might need to go with less gear or a taller tire. That should bring the rpms down some and be more in line with my power range. The little heads ain't gonna do very much more RPMs than about 6500 or so. Or would I be better off to tighten up the converter?

[Marty Chance]

The real test of "driving through" the converter is how the converter holds the power on the gear change , in other words how much rpm drop there is on the shift . To gauge this acurately you will need something to record engine rpm going down track.