KEEPING THE STOCK FIERO ENGINE: Looking to buy a Fiero with a manual transmission but would like to swap out to a different tranny that will lower my RPM's at highway speed.
Which is a good manual transmission (and from what vehicle) to be used with a stock Fiero engine? Does anything need to be modified and do I need custom parts?
Looking for a taller top gear? You may not like the result. Even the V6 with a Getrag does not have much oomph left in 5th gear....it's something like 0.72. If you want to pass somebody you are going to drop it to 4th gear, or you won't make it.
[This message has been edited by Gall757 (edited 01-02-2015).]
If you don't already have the Isuzu 5 speed (stock 85-88 4cyl Fieros), then swap one in. If you already have the Isuzu 5 speed, then there aren't any other real options... the F40 would lower the cruise RPM some more, but it will be difficult to justify the cost of the swap via fuel economy.
By the sound of it. I think I'm better of with an auto and throw in a 4T60 to lower my RPM's.
I don't know how or why you're drawing that conclusion from the responses in this thread.
I swapped a 5-spd Isuzu into my '84 Fiero and I couldn't have been happier with the result. I autocrossed that car for four years, and the gearing was just fine for making good use of the limited power of the 4-banger duke... as well as having a fuel-saving 5th gear for the freeway. Absolutely no complaints with that tranny swap at all.
I don't know how or why you're drawing that conclusion from the responses in this thread.
I swapped a 5-spd Isuzu into my '84 Fiero and I couldn't have been happier with the result. I autocrossed that car for four years, and the gearing was just fine for making good use of the limited power of the 4-banger duke... as well as having a fuel-saving 5th gear for the freeway. Absolutely no complaints with that tranny swap at all.
Is there a way to tell what manual transmission it has? Because from the sound of it, it sounds as if the 5-speed Isuzu is what I'm looking for. What my fear is is that I'll be at high RPM's at highway speed which will decrease my fuel economy BIG time! What's the RPM's on your car at 70MPH using the 5-speed Isuzu transmission?
The engineers at Pontiac knew what they were doing. The 5 speed isuzu is optimal for the Duke, and the Getrag 5 speed is good for the V6. Even the econo MY8 4 speed was set up for great mileage....(that transmission could get 42 mpg in 1984!). I don't think you can improve much on any of those transmissions, considering the power available. If you are looking for good mileage, avoid the automatic trans, and the M19 'sport' transmission available in 1984. All the others are as economical as you can get.
I've used the Isuzu behind V6's in two of my cars. They held up well even with agressive mountain driving, but I never tried to burn rubber in any gear. RPM at 70 was somewhere in the neighborhood of 2500 if I recall correctly. Here in the Georgia Piedmont area, one of the cars that had over 200K would need to be dropped to 4th for some hills. The other identical car with a little healthier lower mileage engine could usually cruise on up those hills in 5th, but both often needed 4th gear to pass another vehicle on 2 lane roads. The Isuzu trans was very comfortable in the mountains pushing 65 in 3rd gear on the straights between curves. These were identical 85GT's.
My 87GT has a Getrag and a 3.4 and it will comfortably stay in 5th gear on most any road except for the steepest of grades. It's not the transmission that allows this. Lots of low end torque in the 3.4. Something the 2.8 doesn't have.
Is there a way to tell what manual transmission it has? Because from the sound of it, it sounds as if the 5-speed Isuzu is what I'm looking for. What my fear is is that I'll be at high RPM's at highway speed which will decrease my fuel economy BIG time! What's the RPM's on your car at 70MPH using the 5-speed Isuzu transmission?
Depends on the model / year.
4 cyl Fieros got the 4-speed Muncie and the 5-Speed Isuzu. (4-speed for the 1984 model year, and the 5-speed for 85-88).
V6 Fieros got the 4-speed Muncie from 85-86, and the 86.5 GT Fastback and ALL 87/88 V6s got the 5-Speed Getrag.
Yeah I guess getting a 5-speed would be best choice. I live in Vegas and highway speed limit is 65MPH but of course, no one does that. But what's that have to do with anything??
I currently drive a 1986 Toyota MR2 w/ manual transmission and at 70MPH it's at about 4,000RPM and don't want the same issue if I get a Fiero
Yeah I guess getting a 5-speed would be best choice. I live in Vegas and highway speed limit is 65MPH but of course, no one does that. But what's that have to do with anything??
I currently drive a 1986 Toyota MR2 w/ manual transmission and at 70MPH it's at about 4,000RPM and don't want the same issue if I get a Fiero
A fiero and MR2 are very different. Any fiero will not have 4,000RPM's when doing 70 unless something is wrong with the car (horrible wrong.)
Your MR2 will keep it's value more, but a Fiero will get more looks.
Yeah I guess getting a 5-speed would be best choice. I live in Vegas and highway speed limit is 65MPH but of course, no one does that. But what's that have to do with anything??
I thought the limit may have been 75 or 80 mph. Maybe someone can chime on what RPM the engine is doing in 5th gear at 65mph.
The Getrag is geared for a balance between top gear efficiency and responsiveness. IMO they could have put a taller 5th gear in and still retained decent highway performance, but its a moot point.
In 5th gear at 65 mph I think the 2.8 would be running around 2500 RPM.
Two or three years ago I read part of a report about transmissions and their effect on engine life. It seems that vehicles with automatic transmissions, in general, tend to require fewer engine repairs and have higher longevity. Manual transmission equipped vehicles of course, tended to life a shorter life.
There were some theories about why this was. Some of those were that automatic transmissions were programmed to shift at the proper times depending upon the load placed on them and the engine rpm. So that leads me to think that even with aggressive driving, over-driving the engine is less likely. They felt that the inverse was the case with the manually equipped vehicles in that persons who selected a manual transmission were generally more aggressive drivers and more frequently approached the rpm limits of the engine, or at least pushed the engine to higher rpm ranges as compared to what an automatic transmission would.
There was a brief comparison of 4 and 5 speed manual transmission vehicles and the one thing I remember about that comparison was that people tend to lug an engine in 5th gear rather than downshifting to 4th. That low 5th gear rpm combined with the reduced oil flow and extra stress put on the engine parts can cause early engine failure.
If we accept that statement, then the 5 speed manual transmission vehicles would have shorter engine lifespans in mountainous or hilly regions as opposed to areas such as where dansical or maryjane live.
