700R4 ratios

[peter paul fenske]

HI George

Well the TPI in my truck gives me about
20 MPG irregardless of what I do..
Definitely better than CARB.
Although at 90 MPH
Am using 3.08 in truck with 700R4..

I guess you could try bumping the timing.
I am running 14 initial and can still use reg.
Seldom does knock show up on the scanner
This timing is worth 2MPG over stock..

You could also play with the timing map.
Also lock up the TCC earlier but this gets to be a pain..

Mind you I forget if you are using a TPI ecm.
The TBI does strange things..
and will run a wee bit rich on a TPI although prob ok.

Cya:peter

At 07:20 PM 7/14/97 -0500, you wrote:
>Gentlemen, it's official. MY TPI has actually lost about 1mpg in the city.
>Highway milage aint worth bragging about either. I simply must have the best
>fuel economy possible with the '89 GM 5.7L TPI system. What does the TPI
>engine & ECM like as far as final drive ratio?? I'm at a loss as to why my
>TPI system is not performing at it's best. Any ideas? Do I need to drop to a
>lower gear ratio? Below is a engine speed vs vehicle speed data set. This is
>calculated data, but it aggrees with my instruments. 2.73:1 rear end ratio
>27.125" dia tires. Thanks for the data Chief!
>
>rpm     1st 3.06        2nd 1.62        3rd 1.0         4th 0.70
>500	4.829933	9.123207	14.7796	        21.11371
>600	5.79592	        10.94785	17.73551	25.33645
>700	6.761906	12.77249	20.69143	29.55919
>800	7.727893	14.59713	23.64735	33.78193
>900	8.69388	        16.42177	26.60327	38.00467
>1000	9.659866	18.24641	29.55919	42.22742
>1100	10.62585	20.07106	32.51511	46.45016
>1200	11.59184	21.8957	        35.47103	50.6729
>1300	12.55783	23.72034	38.42695	54.89564
>1400	13.52381	25.54498	41.38287	59.11838
>1500	14.4898	        27.36962	44.33879	63.34112 (I show 65mph at 1500rpm)
>1600	15.45579	29.19426	47.29471	67.56386
>1700	16.42177	31.0189	        50.25062	71.78661
>1800	17.38776	32.84355	53.20654	76.00935
>1900	18.35375	34.66819	56.16246	80.23209
>2000	19.31973	36.49283	59.11838	84.45483
>2100	20.28572	38.31747	62.0743	        88.67757
>2200	21.25171	40.14211	65.03022	92.90031
>2300	22.21769	41.96675	67.98614	97.12306
>2400	23.18368	43.79139	70.94206	101.3458
>
>Help'
>GMD
>
>At 02:59 PM 6/13/97 -0400, I wrote:
>>>...I've wrote
>>>it off to my 2.73:1 gear ratio and 27-1/8" diameter P255 60-15's. Does
>>>anyone have the gear ratios for the 700R4 tranny? It seems like my gas
>>>milage in the city has dropped from 13 -14 to 12-13. Dope!
>>>
>>>GMD
>>
>>Ratios are 3.06, 1.62, 1.00, 0.70.
>>
>>Ed Hilker aka "Chief"
>>84'SS - 700R4
>>
>>
>>
>George M. Dailey
>gmd at tecinfo.com
>
>