if i remember right early (1990) zr1's were faster than later models... WHy?
05-02-2011, 10:19 PM
#1
Race Director
Thread Starter
if i remember right early (1990) zr1's were faster than later models... WHy?
When the zr1 came out, I was an 8th grader with a subscription to motor trend. I was totally fascinated by numbers.
How could this car beat a lamborghini? (countach)? Its neat.
As the years went on (and zr1 got a litte more HP), it seemed to get slower.
More than just a variation between one magazine's test numbers vs. the others. (i think C&D and motor trend always seemed to get the fastest times).
0-60 MPH and quarter mile were faster in the earlier models.
Where it used to be a 4.3 second 0-60 car, now it was a >4.9 second 0-60 car
Does anyone know why that was? Weight? tuning? what caused it?
or is this not true.
How could this car beat a lamborghini? (countach)? Its neat.
As the years went on (and zr1 got a litte more HP), it seemed to get slower.
More than just a variation between one magazine's test numbers vs. the others. (i think C&D and motor trend always seemed to get the fastest times).
0-60 MPH and quarter mile were faster in the earlier models.
Where it used to be a 4.3 second 0-60 car, now it was a >4.9 second 0-60 car
Does anyone know why that was? Weight? tuning? what caused it?
or is this not true.
05-02-2011, 10:36 PM
#2
Drifting
So rumor has it that the 90s had 400hp....as they aged and added ASR they got alittle heavier, but it could be also that the ASR can block the throttle body if its not set correctly....so maybe there is more than one factor.
A few of later test I have read about were done in some pretty poor conditions ...90+ degree, etc.
I wonder if the first ZR-1s with steel have shafts might have used the extra weight to gain some traction at launch...
It also did not hurt to have John Heinrecy driving in the original test runs.
A few of later test I have read about were done in some pretty poor conditions ...90+ degree, etc.
I wonder if the first ZR-1s with steel have shafts might have used the extra weight to gain some traction at launch...
It also did not hurt to have John Heinrecy driving in the original test runs.
05-03-2011, 12:10 AM
#5
Safety Car
I have never driven a 90, but I have my 91 now and had the pleasure of driving and racing against my dad's 91 bought new in late 91. They run 13.0-13.2 in full street trim at 109-110 mph like the test averages seem to indicate.
I had a 12.8-13.0 second Camaro at the time and it always got the hole shot hard on the LT5 due to the nature of its powerband and porky curb weight.
I think Motortrend had the ringer ZR-1 as they claimed 112-113 mph stock at 12.8 or something like what a car with tires and about 35 hp extra would do. I remember that test to this day- just no way that the typical car off the showroom was turning traps like that- I was there to witness that back then and verify it against my mildly modded 91 today that is maybe in the 112 mph trap speed range.
As far as the variations- I offer two possibilities:
1) weather conditions- hot air pulled lots of ignition timing on the LT5. If you have one of these cars, you know this to be true.
2) slow shifting can cause secondary intake ports to close between shifts and there is a tenth or two to open them up full when the throttle comes back to 100%. A couple of slow shifts could cost a tenth or two.
I had a 12.8-13.0 second Camaro at the time and it always got the hole shot hard on the LT5 due to the nature of its powerband and porky curb weight.
I think Motortrend had the ringer ZR-1 as they claimed 112-113 mph stock at 12.8 or something like what a car with tires and about 35 hp extra would do. I remember that test to this day- just no way that the typical car off the showroom was turning traps like that- I was there to witness that back then and verify it against my mildly modded 91 today that is maybe in the 112 mph trap speed range.
As far as the variations- I offer two possibilities:
1) weather conditions- hot air pulled lots of ignition timing on the LT5. If you have one of these cars, you know this to be true.
2) slow shifting can cause secondary intake ports to close between shifts and there is a tenth or two to open them up full when the throttle comes back to 100%. A couple of slow shifts could cost a tenth or two.
05-03-2011, 08:15 AM
#6
Race Director
he and I use to joke about it. At the time I wanted a ZR-1 VERY badly, but had my 89 that ran the same ET and a couple MPH less.
05-03-2011, 02:32 PM
#8
Burning Brakes
Hello:
I've heard from/read different sources stating that the early 90 (VIN<=600) motors had 'special attention' paid to cam timing during the build process. Reasons for this were varied, but all seemed to point to GM wanting to make certain the early cars ran the best numbers (a fair deduction given the sheer cost of the LT5 project).
I remember a red/red 90 running at Beech Bend in 1994 at the Museum's Grand Opening; he was turning 12.8s@112. It was completely stock down to the original Gatorbacks; didn't even have a cut air filter lid. I spoke with the owner for a good while (he was in his mid 40s); bought it new and had put less than 3K miles on it in that timeframe. He explained BG was the furthest it had ever been driven, but felt such a 'great car' should be part of the Grand Opening.
The car had run a best of 12.7@113 'up north' where he was from (Chicago I believe), and I remember asking him what mods he had to be running so much better than other ZR-1s (that's when he explained what I outlined above). That was the first time anyone told me about the cam timing on the early MY 90s, and how that could make a measurable difference in performance on a DOHC engine (obviously). I don't remember the exact VIN of his car, but know it was in the 300s.
I didn't recall that conversation until a couple years later (96 or 97), when Greg VanDeventer said the same thing during the Gathering Event at the UPlaza bar late one evening (early morning?
). I suppose the only way to be sure would be to tear down several very early 90s and compare the cam timing to specimens from later in the MY production run, but I don't see that happening anytime soon.
Brian A.
90 ZR-1
ZR WON
01 Z06
not quite stock
I've heard from/read different sources stating that the early 90 (VIN<=600) motors had 'special attention' paid to cam timing during the build process. Reasons for this were varied, but all seemed to point to GM wanting to make certain the early cars ran the best numbers (a fair deduction given the sheer cost of the LT5 project).
I remember a red/red 90 running at Beech Bend in 1994 at the Museum's Grand Opening; he was turning 12.8s@112. It was completely stock down to the original Gatorbacks; didn't even have a cut air filter lid. I spoke with the owner for a good while (he was in his mid 40s); bought it new and had put less than 3K miles on it in that timeframe. He explained BG was the furthest it had ever been driven, but felt such a 'great car' should be part of the Grand Opening.
The car had run a best of 12.7@113 'up north' where he was from (Chicago I believe), and I remember asking him what mods he had to be running so much better than other ZR-1s (that's when he explained what I outlined above). That was the first time anyone told me about the cam timing on the early MY 90s, and how that could make a measurable difference in performance on a DOHC engine (obviously). I don't remember the exact VIN of his car, but know it was in the 300s.
I didn't recall that conversation until a couple years later (96 or 97), when Greg VanDeventer said the same thing during the Gathering Event at the UPlaza bar late one evening (early morning?
). I suppose the only way to be sure would be to tear down several very early 90s and compare the cam timing to specimens from later in the MY production run, but I don't see that happening anytime soon. Brian A.
90 ZR-1
ZR WON
01 Z06
not quite stock
Last edited by ZR WON; 05-03-2011 at 04:04 PM. Reason: spelling
05-03-2011, 05:31 PM
#10
Burning Brakes
Jeff:
I didn't mean that later 90s couldn't run the numbers, only that the earliest ones were purportedly more more consistent in power output due to the cam timing hypothesis. FWIW, my car's VIN is in the 2000's and ran high 12s stock.
Brian A.
90 ZR-1
12.09@118
ZR WON
01 Z06
not quite stock
I didn't mean that later 90s couldn't run the numbers, only that the earliest ones were purportedly more more consistent in power output due to the cam timing hypothesis. FWIW, my car's VIN is in the 2000's and ran high 12s stock.
Brian A.
90 ZR-1
12.09@118
ZR WON
01 Z06
not quite stock
05-03-2011, 07:55 PM
#11
Race Director
Jeff:
I didn't mean that later 90s couldn't run the numbers, only that the earliest ones were purportedly more more consistent in power output due to the cam timing hypothesis. FWIW, my car's VIN is in the 2000's and ran high 12s stock.
Brian A.
90 ZR-1
12.09@118
ZR WON
01 Z06
not quite stock
I didn't mean that later 90s couldn't run the numbers, only that the earliest ones were purportedly more more consistent in power output due to the cam timing hypothesis. FWIW, my car's VIN is in the 2000's and ran high 12s stock.
Brian A.
90 ZR-1
12.09@118
ZR WON
01 Z06
not quite stock
05-03-2011, 10:53 PM
#12
Le Mans Master
When the zr1 came out, I was an 8th grader with a subscription to motor trend. I was totally fascinated by numbers.
How could this car beat a lamborghini? (countach)? Its neat.
As the years went on (and zr1 got a litte more HP), it seemed to get slower.
More than just a variation between one magazine's test numbers vs. the others. (i think C&D and motor trend always seemed to get the fastest times).
0-60 MPH and quarter mile were faster in the earlier models.
Where it used to be a 4.3 second 0-60 car, now it was a >4.9 second 0-60 car
Does anyone know why that was? Weight? tuning? what caused it?
or is this not true.
How could this car beat a lamborghini? (countach)? Its neat.
As the years went on (and zr1 got a litte more HP), it seemed to get slower.
More than just a variation between one magazine's test numbers vs. the others. (i think C&D and motor trend always seemed to get the fastest times).
0-60 MPH and quarter mile were faster in the earlier models.
Where it used to be a 4.3 second 0-60 car, now it was a >4.9 second 0-60 car
Does anyone know why that was? Weight? tuning? what caused it?
or is this not true.
The rumor on Later build 1990 zr-1's and the 1991 and 1992 cars was a person on the assembly line at mercury marine installing the secondary accuators, installed them backwards and the secondary butterflies would not fully open thus causing poor performance.
I had a 1991 zr1, that i bought in 1996 with 300 miles on it. once i got it broken in and put my foot in to it , the car never seemed to perform and it would not rev freely past 6000 rpm. I yanked the plennum off, and sure enough the acuators were not opening the secondary butterflies. they were on backwards. once i corrected the problem, the car performed like it should.
It was a great car. I miss it, but am very happy with the c6 z06.
definently a very different feel and level of performance then my zr-1, a torque monster compared to the lt5.
05-03-2011, 11:47 PM
#13
Drifting
Member Since: Jan 2000
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CI 2-3-4-5-6-7-8-9-10-11-12 Vet
St. Jude Donor '06
Zr-1
Hey -=Jackstands Jeff=-
Are YOU talking about ME?????
My 90 Ran a best of 12.71 @ 113 (100% Stock) in cool temps up north
on the original Gatorbacks.
I ran the 12.65 with a cut lid/KN and Drag Radials.
90's = lighter/quicker
P.S.
-=Jeff=- I will be in town this weekend. I will try to contact you. I want to see your Z!
Last edited by ZR_Don; 05-04-2011 at 07:23 AM.
05-04-2011, 08:30 AM
#14
Race Director
Hey -=Jackstands Jeff=-
Are YOU talking about ME?????
My 90 Ran a best of 12.71 @ 113 (100% Stock) in cool temps up north
on the original Gatorbacks.
I ran the 12.65 with a cut lid/KN and Drag Radials.
90's = lighter/quicker
P.S.
-=Jeff=- I will be in town this weekend. I will try to contact you. I want to see your Z!
Are YOU talking about ME?????
My 90 Ran a best of 12.71 @ 113 (100% Stock) in cool temps up north
on the original Gatorbacks.
I ran the 12.65 with a cut lid/KN and Drag Radials.
90's = lighter/quicker
P.S.
-=Jeff=- I will be in town this weekend. I will try to contact you. I want to see your Z!
I should be around most the weekend. just give me a call
05-04-2011, 10:46 AM
#15
Racer
You could chalk up the good e.t. to driving skills, but the 112-113mph trap speed is a direct indicator of power. Grandma driving the car might be able to pull a good 60ft. time, or not, but if she kept her foot in it she would get a great trap speed regardless.
I couldn't get my bone stock 91' to trap better than 110mph no matter how much I practiced. But the usual bolt-ons gradually brought the speed up, and the e.t. down. I finally gave up hammering it when it turned 12.06@117mph. one warm Florida night.
Gee, if I lived in Chicago, I might have an eleven second car
I couldn't get my bone stock 91' to trap better than 110mph no matter how much I practiced. But the usual bolt-ons gradually brought the speed up, and the e.t. down. I finally gave up hammering it when it turned 12.06@117mph. one warm Florida night.
Gee, if I lived in Chicago, I might have an eleven second car
