Recently rebuilt motor. 30 over, small cam, blocked decked (91/2 - 1 compression), balanced ect. The shift light comes on at 3K rpm and I was wondering how far past 3K do you guys push your 2.8?
The shift light comes on at 3K rpm and I was wondering how far past 3K do you guys push your 2.8?
Ummm... you are aware that the "shift light" on the Fiero indicates shifting for economical driving, right? It does not indicate when the engine is red-lining.
Have you done anything to your intake to improve airflow? If not I don't think much passed 5000 does any good. At this point the engine is gasping for air.
The only time I shift under four grand is when I am sleep driving. Like fierofinder said anything over five is a waste of time. So, somewhere between the two.
In an 85-87 the most you can go is 6012 as that is where the rev limit kicks in, the 88 has no rev limit. At WOT the shift light kicks in at red line, (well just before) the shift light varies on throttle postion and RPM, it is all in the code. And it is NOT gasping for air, it is the cam profile thats drops off in the upper RPM. Next being the coil.
Originally posted by sardonyx247: In an 85-87 the most you can go is 6012 as that is where the rev limit kicks in, the 88 has no rev limit. At WOT the shift light kicks in at red line, (well just before) the shift light varies on throttle postion and RPM, it is all in the code. And it is NOT gasping for air, it is the cam profile thats drops off in the upper RPM. Next being the coil.
And the valvetrain, and the intake, and the exhaust. And the flat tappet.
Going over 4500, you're almost certainly just wasting fuel, as the torque curve has already started coming down pretty quickly after 4000. Going over 5000 and you are definitely wasting gas. Don't bother unless you're on a dyno and seeing what the peak HP number is (stock peak HP is at 5200). Going over 5500 without an upgraded valvetrain, intake, exhaust, fuel, and igntion, with some tuning, and you're just taking unnecessary risk of breaking things.
In an 85-87 the most you can go is 6012 as that is where the rev limit kicks in, the 88 has no rev limit. At WOT the shift light kicks in at red line, (well just before) the shift light varies on throttle postion and RPM, it is all in the code. And it is NOT gasping for air, it is the cam profile thats drops off in the upper RPM. Next being the coil.
I have taken my stock (To the best of my knowledge) 86 GT to over 7000 without it hitting any rev limiter on multiple occasions.
Ummm... you are aware that the "shift light" on the Fiero indicates shifting for economical driving, right? It does not indicate when the engine is red-lining.
quote
Originally posted by fierofinder:
Have you done anything to your intake to improve airflow? If not I don't think much passed 5000 does any good. At this point the engine is gasping for air.
Agreed! Look at your tach instead.
Shift by the time you hit yellow - sooner if you feel the engine "running out of air". At that point it's no longer accelerating hard anyway.
Stock tach doesn't even read that high. And if an aftermerket tach is reading that high, accurately, on a stock 2.8, I'd be worried about mechanical damage. The engine just isn't built for that abuse.
With a high flow fuel pump, gutted cat, ported exhaust manifolds and a cold air intake plumbed under the car with K&N filter my Fiero GT when naturally aspirated with 4 spd could pull strong to 6500 rpm in 1st to 3rd gear and hit 6000 rpm in 4th.....140 mph!
[This message has been edited by I FAR I (edited 08-07-2014).]
With a high flow fuel pump, gutted cat, ported exhaust manifolds and a cold air intake plumbed under the car with K&N filter my Fiero GT when naturally aspirated with 4 spd could pull strong to 6500 rpm in 1st to 3rd gear and hit 6000 rpm in 4th.....140 mph!
IIRC, the max horsepower point for the 2.8L engine is around 5600 RPM.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
With a high flow fuel pump, gutted cat, ported exhaust manifolds and a cold air intake plumbed under the car with K&N filter my Fiero GT when naturally aspirated with 4 spd could pull strong to 6500 rpm in 1st to 3rd gear and hit 6000 rpm in 4th.....140 mph!
Seem like simple changes. You should dyno it and see what was actually gained. When you say high flow fuel pump, which one? 140 Mph, is your car lowered at all?
With a high flow fuel pump, gutted cat, ported exhaust manifolds and a cold air intake plumbed under the car with K&N filter my Fiero GT when naturally aspirated with 4 spd could pull strong to 6500 rpm in 1st to 3rd gear and hit 6000 rpm in 4th.....140 mph!
Seeing you are in Canada, don't you mean 140 KPH? If it was a made for Canada car the MPH are on the outside and MPH are on the inside, I think, I am tired I need a nap ! edit to add OK I had to go look before I take my nap, this is obviously an after market speedo, you sure its right? Mine on my 86 SE only goes to 85 MPH.
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Originally posted by lou_dias:
Pretty sure the stock cam's advertised peak is 4800 rpm.
And he said, the OP that he put a small cam in the car so I would think that means its not a stock cam.
Steve
------------------ Technology is great when it works, and one big pain in the ass when it doesn't
Detroit iron rules all the rest are just toys.
[This message has been edited by 84fiero123 (edited 08-08-2014).]
Originally posted by 84fiero123: Seeing you are in Canada, don't you mean 140 KPH? If it was a made for Canada car the MPH are on the outside and MPH are on the inside, I think, I am tired I need a nap ! edit to add OK I had to go look before I take my nap, this is obviously an after market speedo, you sure its right? Mine on my 86 SE only goes to 85 MPH.
140 kmh ~= 87 MPH. The 86 GT would have had a 120 MPH/200 kmh speedo though.
With stock tires and 4 speed for the 86 GT though, the speed at 6000 RPM in 4th gear would be 152 MPH, not 140.
85 Fiero GT will drive at 24.3 mph per 1000 rpm in 4th gear......24.3 x 6000 rpm = 145.8 mph......My tires are 225/50 15, so I'm subtracting 1 mph per 1000 rpm......The speedo in my car is only to 140 kph, but during this run was spinning round and round in 360 degree revolutions.
[This message has been edited by I FAR I (edited 08-08-2014).]
Seem like simple changes. You should dyno it and see what was actually gained. When you say high flow fuel pump, which one? 140 Mph, is your car lowered at all?
That motor is now gone....worn out after 200k km. The fuel pump was a GM unit for the Syclone and the car had a Hypertech chip. It is lowered with Suspension Technique springs.
[This message has been edited by I FAR I (edited 08-08-2014).]
Originally posted by I FAR I: 85 Fiero GT will drive at 24.3 mph per 1000 rpm in 4th gear......24.3 x 6000 rpm = 145.8 mph......My tires are 225/50 15, so I'm subtracting 1 mph per 1000 rpm......The speedo in my car is only to 140 kph, but during this run was spinning round and round in 360 degree revolutions.
With the 195/70-14 tires (which I think are the stock size for the rear on the 85 GT), it would be about 150 MPH at 6000 RPM in 4th, and with the 225/50-15s it would be about 143 MPH at 6000 RPM in 4th.
But the 85 GT speedo only goes to 85 MPH, and would read 3.7% off from the stock tire size. Also the tachs in Fieros are known to be somewhat inaccurate at higher RPMs. At 4000 RPM though, you would have been going 95 MPH, and the speedo would be going crazy. I really doubt you made it to 6000 RPM in top gear, because the 2.8 just doesn't make power up that high, even with the minor mods you did. Even with the mods that lou_dias did on his 3.4 build, he's not making power up that high yet.
With the 195/70-14 tires (which I think are the stock size for the rear on the 85 GT), it would be about 150 MPH at 6000 RPM in 4th, and with the 225/50-15s it would be about 143 MPH at 6000 RPM in 4th.
But the 85 GT speedo only goes to 85 MPH, and would read 3.7% off from the stock tire size. Also the tachs in Fieros are known to be somewhat inaccurate at higher RPMs. At 4000 RPM though, you would have been going 95 MPH, and the speedo would be going crazy. I really doubt you made it to 6000 RPM in top gear, because the 2.8 just doesn't make power up that high, even with the minor mods you did. Even with the mods that lou_dias did on his 3.4 build, he's not making power up that high yet.
Whatever......I'm not asking you, I'm telling you!
