1985 model year more "pep"?
 

I've heard it said that the 1985 model had more pep. I've heard that it is because of a "bigger turbo" which called for "beefier piston rings", etc. Is there any truth to any of that?

If the 85 turbo was "bigger", then why can't one simply adjust the wastegate for more PSI on the earlier models? Also, a bigger turbo would just take longer to spool up, wouldn't it? I thought the only difference between turbos was the recirculation valve (that people always disconnect for better performance anyway).

I never heard the turbo on the 85's was bigger. I think if you want more power go for a pyrometer and boost guage and establish a base line for exhast temp and start turning the boost up and see what happens.

I know the 85's had a few different features than the early cars. One I have heard about is a locking torque convertor but I don't know if that is true.

The turbo is not bigger, just mounted diffrently on the Cali cars. Mine seems to have less pep. I'm not sure if it is the extra emissions junk or the 2.88 rear that all '85s have. I do like the fuel milage and cruising RPMs that the 2.88 rear gives though!

No locking torque converter clutch. Almost though. It gets to within 98% stall.

The '85 300D should feel about the same off the line. Perhaps slightly peppier. It has a higher stalling torque converter @ 2400 vs 1600 - 1700 rpm.

the 85 federals seem to run more lean than the previous years

If it's a Ca. model car I would think it would have less pep around town, but with the 2.88 gears it would probably be nicer to drive on the highway.

85's would have slightly less pep due to the 2.88 gears in the rear end. They also have a nasty ARV that will drop your boost. If its a Cali car performance will be crippled by the Trap Ox/Ox Cat .

If it has a higher stall t/c, the taller gears would be offset around town with the greater slip within the t/c...........the end result is probably a wash.

I've got the 2.88 gears in the SD and it's been perfectly fine at 2200 rpm to keep up with most traffic conditions off the line.

I believe this to be true also.

I've driven a few 85's and they seem to have less pep than previous years.

IMHO, 83 was the best year. It's got all the updates that occurred in late 82 and no ARV or computer controlled EGR equipment of the 84-Fed85's.

Well, maybe it is just due to adjustment, but my '85 wagon seems to have less turbo lag than other years I have driven. It is the same turbo I believe. Maybe somebody in it's previous life just nailed the alda adjustment.
And, the trannies just seem to shift so much smoother. My best discription is it shifts like a real car, not like many MB autos in the W123 chasis.
Whole lots more vacuum stuff under the hood, and my tach is inop, and much harder to trouble shoot.
Oh, and 2:88 gears seem to be right on the money......

The 85 123's have the vacuum amplifier that watches boost levels and along with the modulator controls the shift hardness more accurately. That's why the 85's tranny feels better.