turbo lag

[waldo786]

In the 85 GN's how bad was turbo lag and what did they do to correct it in 86/87? Is it a computer thing or did they do something else.

[kenmosher]

It's not all that bad, but in 86 the whole header/turbo/throttlebody was redesigned.

The turbo was moved from the rear of the engine to the front, which simplified and shortened a lot of the exhaust runs to the turbo. The throttle body was placed at the top of the plenum after the turbo/intercooler instead of on the inlet to the turbo. The plenum and intake manifold were greatly improved in flow and design.

All of these things contribute to a different experience.

[waldo786]

Is it possible to bolt on the plenum and intake manifold from an 86/87 to an 85 or is that not possible or requires a lot of modification. Also, how much power would one expect if they intercooled an 85? Would it be similar to the 86/87? Thanks!

[kenmosher]

It can definitely be done pretty easily ... intake, plenum, throttle body should all bolt up. Might have to look at linkages and such and do some fabrication (or replace with 86/87 pieces).

Might also need fuel rail from later car as well ...

Biggest problem is that when you get that far, you'll need to get 86/87 headers and turbo and move things to the front of the engine (and coil pack to the back).

It's not trivial, but can defintely be done ... and in the end you have an 86/87 with an 84/85 block.

[1986GN]

Iam Interested In This Up Grade From 84,85 To 86,87 I Have The Complete Intake With Fuel Rail Injectors Included And The Headers And Turbo, Intercooler ......can I Use Same Wirring Harnes I Plan To Up Grade Ecm Also And Coils.....is There Any Place On This Site Where I Can Reserch This Further.....i Know Where Ecm And Ing Coil Up Grades Are But Is There One For Intercooled Corversion Thanks For Any And All Input!!!!

[kenmosher]

Since you have all the parts, you basically just unbolt the old stuff and bolt in the new.

There's articles on the ECM and ignition system here:

http://www.gnttype.org/techarea/ecmsensors/ecmpage.html

Mechanically, it should be pretty much a straight swap, except you'll have to either drill and tap a line in your block for the turbo oil return or have a fitting installed in the oil pan.

[waldo786]

I was wondering how much difference an intercooler would make on an 85? The car I'm looking at the guy selling it has an intercooler he's going to throw in with it. Would I be able to see a big difference if I added that but didn't change the rest? How much difference would you speculate that changing the intake, plenum etc. would make. The engine has just been rebuilt with around 1,500 miles on it so I don't know if I want to bother doing that. Also what is a good streetable turbo that might be a good upgrade, just to the stock 86/87 or should it be a little larger? Thanks!

[1986GN]

How About Wirrring Harnes Can You Use 84,85 Engine Harnes? For 86,87 Intercooled Up Grade?

[captn23]

when intercooling your hot air car, remember that the more pipe volume you have, the more your turbo needs to work to fill and travel to the engine -resulting in turbo lag. that is what you were initially inquiring about. i never owned a hot air car, but i would assume that throttle response would be better than an 86-7 due to the fact that the charged air shoots straight into the engine. the turbo is right there on top. but like i said -i never owned one so i dont know.
an alternative to intercooling would be alcohol injection, this will cool the air charge and allow you to run more boost. the downside that i see from my alky unit is that my tank empties FAST!!!!
you may want an in-car boost controller w/ this, i know i do.

if you plan on racing the car turbo lag really isnt a concern, but if its a street car remember that what you build on top, you lose on the bottem, where you need it most.
off idle, my car jumps like a 200hp car(turbo lag), but when the turbo spools up -look out!! on a street car it is more important to minimize this than build top end power. i am thinkin bout using a smaller exhaust housing on my turbo, this will further reduce lag but will hurt my top end power. torque converters work well too, but exesive heat can shorten transmission life.
besides, 84-5 engines are really nothing special, all cast parts(no disrespect). so its not hard at all to push these motors past thier limits.
put a buick4.1l long block under the hood and see what it does!?!?!?!?
its a direct bolt-in/on and the extra cubes will make more power AND reduce turbo lag.

[kenmosher]

Originally Posted by 1984TYPE-T

How About Wirrring Harnes Can You Use 84,85 Engine Harnes? For 86,87 Intercooled Up Grade?

Read the link .. it tells in detail what you need to do. Basically, you use the same wiring harness with an additional wire run for the MAT sensor.