[ponjohn]

Is there any reason to believe that Ernie's car would be quicker / faster with a taller gear (3.55 or 3.73)?

[AG]

Probably if he isn't going across the stripe at peak Hp RPM now.

[b-man]

3.73 would be a shorter.gear, not taller.

Tall gears are highway gears, short gears are dragstrip gears.

Just sayin'.

[ta man]

Originally Posted by ponjohn

Is there any reason to believe that Ernie's car would be quicker / faster with a taller gear (3.55 or 3.73)?

Yes it would be quicker..I almost swapped gears to a 3.42 or 3.55 depending on rearend choice last year at this time and was ready to order a stall in the 3800 to 4000 range.

[Steve C.]

In his thread he suggested around 5000 rpm, at least on his factory tach. Based on actual dyno sheets with similar set ups we know the peak power RPM is quite a bit higher than that.

Also, in conversation don't for get converter slippage. He has a Continental torque converter which are known for being well coupled.

554hp @ 5500rpm here:

http://www.sdperformance.com/newsStory.php?newsID=44

.

[ponjohn]

Originally Posted by b-man

3.73 would be a shorter.gear, not taller.

Tall gears are highway gears, short gears are dragstrip gears.

Just sayin'.

OK, numerically larger.

[AG]

Originally Posted by ta man

Yes it would be quicker..I almost swapped gears to a 3.42 or 3.55 depending on rearend choice last year at this time and was ready to order a stall in the 3800 to 4000 range.

TAMAN, I don't think you have any reason to change gears, you are flying now. What is your converter slippage across the line? I have a Redneck 9.5" converter in my race car and it slips 8.2% on the big end.

[ta man]

Originally Posted by AG

TAMAN, I don't think you have any reason to change gears, you are flying now. What is your converter slippage across the line? I have a Redneck 9.5" converter in my race car and it slips 8.2% on the big end.

Its hard to tell..my tach is off a tad...according to Wallace Racing..I should be about 4600 Rpm crossing..I'm sure I see 5000..whether the tach is accurate..so about 8% slippage.Did some more math and I shift into drive right around 97 to 98 mph which is at the 1/8th mile.

[6D9]

If the car hooks it should be faster but have seen it many times it barley improve even with a good hook. Would be a cool test to see. For the marginal performance increase would not be worth the increased rpm on the freeway since no OD.

[Garry Sr]

Originally Posted by ta man

Its hard to tell..my tach is off a tad...according to Wallace Racing..I should be about 4600 Rpm crossing..I'm sure I see 5000..whether the tach is accurate..so about 8% slippage.Did some more math and I shift into drive right around 97 to 98 mph which is at the 1/8th mile.

They need to lay an eighth out where I've been street racing. If you're going to go all outlaw on me let's do it right. I don't mind winding second a little higher than you.

[ta man]

Originally Posted by 6D9

If the car hooks it should be faster but have seen it many times it barley improve even with a good hook. Would be a cool test to see. For the marginal performance increase would not be worth the increased rpm on the freeway since no OD.

I agree when I used to drive to the track with the 3.42's it felt like a much longer drive.

[Torquewar]

I have 3:42s and I'm crossing at 5200.
Ernie and me run the same converter and pretty much identicle times.
We have talked about upping the gear and converter to get the car moving out of the hole.
It really is a balancing act in regards to street/highway driving and race .I also looked at a 38-4k upgrade ,so a call was made to Continental
Cant remember who I talked to but he highly recommended a 3:73 gear set .

[ta man]

It would be a ride for sure when the track is crappy..!

[Garry Sr]

3:42 isn't a bad all around gear at all. I'm running massive duration and the high stall and 3:73 pretty much belong with it.

[Garry Sr]

That being said I can't knock what ta man has accomplished with that 3.08 gear. He'd probably kick my ass.

[slowbird]

I bet you dont gain much. We went from 3.73 to 3.08 with a 428 and didn't see much i think it was .05. It would be an interesting test though.

[Garry Sr]

I went from a 4.11 in my 69 to a 3.55 and I wasn't happy at all. That being said I had way more into my other engine and it was on spray.

[1lemans]

I went from 3.23 to 3.73 same time and mph wtf?

[Garry Sr]

On my 69 I ended up going to a smaller diameter tire to compensate for the gear change. I still wasn't happy.

[Formulajones]

Keep in mind simply changing the gear changes other variables. When dealing with an automatic, taking his 3.08 out of there and installing say....3.73's. Now his converter isn't going to flash as high, will drive around tighter and may change the whole attitude of the car in a not so good way.
In order to take advantage of the steeper gear, most likely a converter swap would be necessary at the same time. Something a tad looser to make the car act the way it does now. That would be a more apples to apples comparison.

My father just had Continental build a new converter for his 571. Currently 3.73 gears. Bischoff who built the motor suggested staying with 3.73's for best ET's but my father having more street driving in mind wanted to drop it to a 3.25 with the new 9". Continental said they couldn't build a converter tight enough to harness the torque with 3.25's and said at minimum he would need to run a 3.50 gear for the converter to couple and work properly.

Right now that converter is in the car with the current 3.73's and it works absolutely beautiful on the street. It will drive a tad looser with the 3.50 gear set.