I recently drove my bone-stock '87 Limited from Denver to the Florida Gulf coast for a few days. (thanks to those who helped me get my waste gate actuator length issue resolved - it was 1/2" short! Car was much more docile when set properly.) I noticed several rather profound differences in performance which have given me an agenda for my winter project(s). However, I need to get some advice on one of the starting points.
I have noticed in Denver that the car has a slight lag, and doesn't make as much boost as it did at sea level (no surprise there, of course). What I would like to do is replace the stock turbo with a unit that is 1.) a stock look-alike and 2.) is sufficiently "aggressive" to spool up at 5500 feet the same way the stock one does at sea level. I also recognize that a change in torque convertor is probably nearly mandatory with the sort of change I'm proposing.
Any suggestions (including any direction to charts for the various turbos) would be appreciated. I have read through the article in the tech area regarding compressor flow calcs. I need some data (or advice) to be able to make better use of this article.
TIA
A TA49---no change in converter required but a set of 36# or larger should be done at the same time. Look at the turbo/injector chart on this site under technical resources, turbos....or a vendor's site such as PTE.
I don't have any specific recommendation for you, but you are right, you need something bigger at altitude than you do at sea level.
For example, to move 300 gm/s of air at sea level the compressor has to pull in about 578 cfm, but in El Paso where the local pressure is about 12.8 psia it would have to pull in about 670 cfm to get that same mass air flow.
When you look at the Turbonetics compressor curves the X axis is in mass flow (lbs/min), but that is *corrected* mass flow, it has to be corrected to a standard pressure. A compressor like this is really a *volume* machine, they should have used cfm for the X axis instead to get away from that correction requirement.
That being said, for a basically stock car like yours, a TA-49 is probably a good choice.
John Estill