87 just seems slow compared to 85
10-14-2016, 04:31 PM
#1
Oil Producer
Thread Starter
87 just seems slow compared to 85
Hi guys. Now that I am on my 87 overhaul/restoration/mod i am methodically going through the car as I still drive when the weather is good.
Something that has always bothered me about the 87 is that sometimes it just doesn't have the same torque as the 85 does.
Granted, fully SOTP meter but we did take both cars out and do a test and the 85 is much faster on acceleration than the 87.
The 87 runs excellent, smooth, it has some leaks in a few spots but those are just seals.
I did a compression test on the car and they all came in great at 150psi +/- 2psi. I did not do any leakdown testing but with numbers that close I gotta believe that I don't have any random burnt exhaust valve somewhere robbing me of compression on one cylinder. I put new plugs in the car, tested the spark plug wires and they all ohmed less than 5 ohms resistance.
they have the same rear end.
the one thing they DO NOT have the same of is the 85 stock torque converter is 2400rpm. The 87 stock torque converter is 1300 (!!!! might be 1400 but its still a tonne different)
The 85 is like rip your face off fast. it will spin the tires if you want. the 87 will spin the tires sometimes but not often. likely depending on friction conditions with temperature and road surface. the 85 will loosen the tires whenever you want. I have ran two sets of tires on BOTH cars and its the same thing so its not like the 85 has dried out hard tires and the 87 doesn't.
I have a feeling that is all it is but wanted to ask you guys what you thought.
Something that has always bothered me about the 87 is that sometimes it just doesn't have the same torque as the 85 does.
Granted, fully SOTP meter but we did take both cars out and do a test and the 85 is much faster on acceleration than the 87.
The 87 runs excellent, smooth, it has some leaks in a few spots but those are just seals.
I did a compression test on the car and they all came in great at 150psi +/- 2psi. I did not do any leakdown testing but with numbers that close I gotta believe that I don't have any random burnt exhaust valve somewhere robbing me of compression on one cylinder. I put new plugs in the car, tested the spark plug wires and they all ohmed less than 5 ohms resistance.
they have the same rear end.
the one thing they DO NOT have the same of is the 85 stock torque converter is 2400rpm. The 87 stock torque converter is 1300 (!!!! might be 1400 but its still a tonne different)
The 85 is like rip your face off fast. it will spin the tires if you want. the 87 will spin the tires sometimes but not often. likely depending on friction conditions with temperature and road surface. the 85 will loosen the tires whenever you want. I have ran two sets of tires on BOTH cars and its the same thing so its not like the 85 has dried out hard tires and the 87 doesn't.
I have a feeling that is all it is but wanted to ask you guys what you thought.
10-14-2016, 06:56 PM
#2
Team Owner
What about gear ratios? The base A4 rearend was a 2.73 and there was an optional 3.07 for both years. Could it be that the '87 has the 2.73?
The '87 had 240HP/345TQ compared to the '85 230HP/330TQ so one would expect that the 87 would have a little better performance.
Where did you find the converter specs? An 1100 RPM difference sounds like a lot. Because there were so many similarities between the 85 and 87 (except for the cylinder heads) I would have expected that the TC would have similar stall numbers. The A4 gear ratios for both years were the same and so were the gear ratios for the 4+3 trans.
The '87 had 240HP/345TQ compared to the '85 230HP/330TQ so one would expect that the 87 would have a little better performance.
Where did you find the converter specs? An 1100 RPM difference sounds like a lot. Because there were so many similarities between the 85 and 87 (except for the cylinder heads) I would have expected that the TC would have similar stall numbers. The A4 gear ratios for both years were the same and so were the gear ratios for the 4+3 trans.
10-16-2016, 09:19 PM
#3
Advanced
Interesting comments. I have a similar concern. I bought a new 81 in 1982 and in 1984 I traded it in for an 84. The difference in performance was significant. The 84 was faster, quicker and when I ran over a quater I could tell if it was heads or tails, well almost.
Eventually I returned to family cars until I bought my 1987 base vert. It is nothing like I remember my 84 being. I mean it drives and rides like a 52 Buick Roadmaster. Or at least it seems to. I'm at a loss. Like yours my engine seems to be running as designed. I don't drive it often, it's a toy but I'm really disappointed. Don't know what I'm gonna do but I feel the need to do something.
Eventually I returned to family cars until I bought my 1987 base vert. It is nothing like I remember my 84 being. I mean it drives and rides like a 52 Buick Roadmaster. Or at least it seems to. I'm at a loss. Like yours my engine seems to be running as designed. I don't drive it often, it's a toy but I'm really disappointed. Don't know what I'm gonna do but I feel the need to do something.
10-16-2016, 11:56 PM
#4
Melting Slicks
Hi guys. Now that I am on my 87 overhaul/restoration/mod i am methodically going through the car as I still drive when the weather is good.
Something that has always bothered me about the 87 is that sometimes it just doesn't have the same torque as the 85 does.
Granted, fully SOTP meter but we did take both cars out and do a test and the 85 is much faster on acceleration than the 87.
The 87 runs excellent, smooth, it has some leaks in a few spots but those are just seals.
I did a compression test on the car and they all came in great at 150psi +/- 2psi. I did not do any leakdown testing but with numbers that close I gotta believe that I don't have any random burnt exhaust valve somewhere robbing me of compression on one cylinder. I put new plugs in the car, tested the spark plug wires and they all ohmed less than 5 ohms resistance.
they have the same rear end.
the one thing they DO NOT have the same of is the 85 stock torque converter is 2400rpm. The 87 stock torque converter is 1300 (!!!! might be 1400 but its still a tonne different)
The 85 is like rip your face off fast. it will spin the tires if you want. the 87 will spin the tires sometimes but not often. likely depending on friction conditions with temperature and road surface. the 85 will loosen the tires whenever you want. I have ran two sets of tires on BOTH cars and its the same thing so its not like the 85 has dried out hard tires and the 87 doesn't.
I have a feeling that is all it is but wanted to ask you guys what you thought.
Something that has always bothered me about the 87 is that sometimes it just doesn't have the same torque as the 85 does.
Granted, fully SOTP meter but we did take both cars out and do a test and the 85 is much faster on acceleration than the 87.
The 87 runs excellent, smooth, it has some leaks in a few spots but those are just seals.
I did a compression test on the car and they all came in great at 150psi +/- 2psi. I did not do any leakdown testing but with numbers that close I gotta believe that I don't have any random burnt exhaust valve somewhere robbing me of compression on one cylinder. I put new plugs in the car, tested the spark plug wires and they all ohmed less than 5 ohms resistance.
they have the same rear end.
the one thing they DO NOT have the same of is the 85 stock torque converter is 2400rpm. The 87 stock torque converter is 1300 (!!!! might be 1400 but its still a tonne different)
The 85 is like rip your face off fast. it will spin the tires if you want. the 87 will spin the tires sometimes but not often. likely depending on friction conditions with temperature and road surface. the 85 will loosen the tires whenever you want. I have ran two sets of tires on BOTH cars and its the same thing so its not like the 85 has dried out hard tires and the 87 doesn't.
I have a feeling that is all it is but wanted to ask you guys what you thought.
My friend had an 87 that had similar performance when my 85 was stock, yes they can launch well with that tree stump pulling first gear.
The early TPI's all ran mid to low 14 sec quarter mile, depending on the rear gears.
10-17-2016, 11:57 AM
#5
Team Owner
The 85 does have 24lb injectors they run at 30 psi, if the fuel pressure regulator had been replaced it might be more like 40 psi now.
My friend had an 87 that had similar performance when my 85 was stock, yes they can launch well with that tree stump pulling first gear.
The early TPI's all ran mid to low 14 sec quarter mile, depending on the rear gears.
My friend had an 87 that had similar performance when my 85 was stock, yes they can launch well with that tree stump pulling first gear.
The early TPI's all ran mid to low 14 sec quarter mile, depending on the rear gears.
10-17-2016, 12:59 PM
#6
Intermediate
How about your timing? I'd be checking coil for spark too. You could have a weak coil or ignition module sending weak signal to coil. Also if the timing is not on par, power will suffer greatly. I'd also check timing chain diflection, because that can affect power as well.
10-17-2016, 04:27 PM
#7
Team Owner
Member Since: Oct 2004
Location: altered state
Posts: 81,242
Received 3,043 Likes
on
2,602 Posts
St. Jude Donor '05
TC and gears can make a huge difference
Drove a very low mile perfect 88 yrs ago was stumped why it seemed so sluggish compared to an 89 auto I once had. Even in P throttle reponse (with everything being just right worked on it a lot) was a stone in comparison
Want to drive something with real bad throttle reponse? My 02 Truck drive by wire...like basketball slow.
My 850 DP Holley has more throttle response than any EFI car Ive had except one and its still not "perfect".
Drove a very low mile perfect 88 yrs ago was stumped why it seemed so sluggish compared to an 89 auto I once had. Even in P throttle reponse (with everything being just right worked on it a lot) was a stone in comparison
Want to drive something with real bad throttle reponse? My 02 Truck drive by wire...like basketball slow.
My 850 DP Holley has more throttle response than any EFI car Ive had except one and its still not "perfect".
10-17-2016, 04:42 PM
#8
Oil Producer
Thread Starter
thanks all for the suggestions.
i'll start by comparing the reas ends but i recall having done this once and i believe they are the same in the stickers. they may have been changed i suppose.
ill check timing and spark too. as for timing chain diflection, that means stretch right? a slightly stretched timing chain would mean that when im at 8dbtdc id be at say 7?
i'll start by comparing the reas ends but i recall having done this once and i believe they are the same in the stickers. they may have been changed i suppose.
ill check timing and spark too. as for timing chain diflection, that means stretch right? a slightly stretched timing chain would mean that when im at 8dbtdc id be at say 7?
How about your timing? I'd be checking coil for spark too. You could have a weak coil or ignition module sending weak signal to coil. Also if the timing is not on par, power will suffer greatly. I'd also check timing chain diflection, because that can affect power as well.