Does engine size make a difference?

One of the most critical areas of a automatic race car

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camaroman9
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Does engine size make a difference?

#1 Post by camaroman9 » Mon Jul 12, 2010 12:02 am

I had Marty build me a converter for my 6" rod 388 last year. We are now running a 5.7 rod 355 because we are freshening up mine and getting it ready for bigger and better things. How much of a difference should there be? My car is real lazy naturally aspirated (1.70 60 foots). On the bottle I can't seem to keep the damn thing off the rev limiter in first gear. I did notice the other day that it's only dropping 200 rpm or so on the 2-3 shift.
C&S carbureted 388 SBC, PT106, TH400, e85
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CDR Performance
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Re: Does engine size make a difference?

#2 Post by CDR Performance » Mon Jul 12, 2010 6:53 am

200 rpm is no enough drop.
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Re: Does engine size make a difference?

#3 Post by John_Heard » Mon Jul 12, 2010 6:57 am

That sounds real loose - how are you measuring it?

I went and looked at some old passes, and my 2-3 shift was 1400 rpm drop - course this is going to vary with how tight the converter is, etc. but 200 rpm is not much. What is it on the 1-2?

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camaroman9
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Re: Does engine size make a difference?

#4 Post by camaroman9 » Mon Jul 12, 2010 7:14 am

This is just what I saw last Friday when we went to mokan. I don't have a logger so I have to look at the tach when I shift. The 1-2 seemed to have a little more drop but not much more than the 2-3 shift.
C&S carbureted 388 SBC, PT106, TH400, e85
http://www.timsbodyandglass.com
Special thanks to:
Bentune Performance & Fabrication (417)483-5584
Performance Coatings + (417)439-0546
C&R Transmission (417)736-2191

Marty Chance
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Re: Does engine size make a difference?

#5 Post by Marty Chance » Mon Jul 12, 2010 7:40 am

what rpm do you shift at ? If you short shift there will be little drop.
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camaroman9
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Re: Does engine size make a difference?

#6 Post by camaroman9 » Mon Jul 12, 2010 8:08 am

I am shifting right around 7200 on the bottle. On the motor I am shifting around 6800 and it drops about 600 rpm.
C&S carbureted 388 SBC, PT106, TH400, e85
http://www.timsbodyandglass.com
Special thanks to:
Bentune Performance & Fabrication (417)483-5584
Performance Coatings + (417)439-0546
C&R Transmission (417)736-2191

Marty Chance
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Re: Does engine size make a difference?

#7 Post by Marty Chance » Wed Jul 14, 2010 11:51 am

Sounds alittle loose. If you are 1/8 mile racing and you do not plan on running any more nitrous then 600 rpm drop is livable, but if you want to add more nitrous you will need to tighten the converter.
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