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I was on a track with several miles in a stretch straight aways. I was cruising at 90 and pushed it up to 150 mph and my rpm's were at 4400. My cam makes power up to 5300 so I feel comfortable saying I think my car could reach 160 mph at top end. Maybe more if there is enough room?
Maybe, but it depends on what you have done to the car. My 89 (bone stock, 75k) topped out at 140 MPH @ 42-4300 RPM. I had more room, the car just did not have anything more to give. I do not think you are RPM limited, but are drag limited by the power you are making.
I had a cracked block in 2011. During that time I read about different ways to modify the L98.
Ported and gasket matched 113 heads
Long tube headers, MagnaFlow cats, Flowmaster 40 mufflers 2.5" pipe
Comp cam 08-501-8 roller rocker arms
reduced pulley set 3
adjustable fuel pressure set at 40 psi 24lb fuel Injectors
1.5 roller rockers
balanced motor
Edelbrock 3860 intake manifold
SLP runners ported
Edelbrock water pump 2 row aluminum radiator ( better cooling no hp gain)
700R4 with a shift kit adjusted pressure cable so down shifting happens quickly
Eliminated 10lb Frisbee after I bought the car!
2:59 gears which allow the car to really go go go. It takes allot to get the engine to rev to 5000
Like I said I was cruising along and noticed lots of open road ahead of me and got the rpm's up to 4400 and hit 150 mph in D. I know this is a brick wall so to speak. Stock I had the pedal to the floor and could not get it over 144 mph. This was the first time I had ever gotten up past 140 mph since the rebuild.
I was on a track with several miles in a stretch straight aways. I was cruising at 90 and pushed it up to 150 mph and my rpm's were at 4400. My cam makes power up to 5300 so I feel comfortable saying I think my car could reach 160 mph at top end. Maybe more if there is enough room?
That's what the car was designed to do and apparently, 28 years later, it still can.
Last edited by mtwoolford; 12-16-2016 at 02:12 AM.
Last summer I had the joy and privilege of driving my new-to-me 95 on the Indy track. Led to believe that we would be lucky to be allowed to hit 65 I entered the track in confidence, not giving my mismatched, aging, off brand tires a second thought. As the Vette in front of me stopped and allowed the pack to run to the end of the back straight he lit up and hit 145 with his C5. How could I resist. I nailed it and saw triple digits before I conside red how those black marks on the wall came to be and settled for a 100MPH marker. No photo of the speedo but the blur of the landscape remains strong.
I don't own a Go Pro camera. If anyone doesn't believe that my C4 didn't hit 150 mph at 4400 rpm's and needs proof with a picture all I can say is fly to Arizona. I will pick you up at the airport and you can hold a camera on my speedo and snap away as we hit triple digits. On the track of course which is about 15 minutes from Skyharbor airport.
No different than going 75 mph. All four tires 275 40 17, 32 lbs psi
Interesting.
On my '85 Z51 it felt like it was a little "darty" at normal highway speeds. It was probably just the quick response of the Z51, but as I got to high speeds it actually felt more stable.
Last summer I had the joy and privilege of driving my new-to-me 95 on the Indy track. Led to believe that we would be lucky to be allowed to hit 65 I entered the track in confidence, not giving my mismatched, aging, off brand tires a second thought. As the Vette in front of me stopped and allowed the pack to run to the end of the back straight he lit up and hit 145 with his C5. How could I resist. I nailed it and saw triple digits before I conside red how those black marks on the wall came to be and settled for a 100MPH marker. No photo of the speedo but the blur of the landscape remains strong.
your lucky they didn't throw you off the track. The watering hole dive bar I used to drink at is just north of the track there in Speedway.I always thought the sounds coming off the track during testing was better than the juke box music. BTW. some idiot took his bicycle for a lap or two around the track. lol, he did make at least one lap b4 the Speedway police stopped him. Also,the cops have a sign near the jail cells that you walk by that says, Welcome Race Fans". You gotta admire their sense of humor.
Last edited by ghoastrider1; 12-16-2016 at 09:45 AM.
I want to add this fact to open discussion. My modified L98 runs on 87 octane cheap gas. The builder talked me into keeping the compression stock. I entretained bumping up the compression to gain more horsepower. The builder asked Do you want to have to buy expensive gas? So I kept it on 87. This car has heart and it's a 5.7L not a stroker. Putting this engine in a 1989 ZF transmission car would be a fun project.
I want to add this fact to open discussion. My modified L98 runs on 87 octane cheap gas. The builder talked me into keeping the compression stock. I entretained bumping up the compression to gain more horsepower. The builder asked Do you want to have to buy expensive gas? So I kept it on 87. This car has heart and it's a 5.7L not a stroker. Putting this engine in a 1989 ZF transmission car would be a fun project.
Shouldn't you be on 93 anyways at stock? The logs I remembered eons ago, there was more knock count when accelerating at 87 vs 93.
1988 Corvette L98 is at 9.5 compression. 87 octane gas and it screams. I am currently spending $1.89 gallon.
Have you scanned it for knock counts with different gas? I did and noticed less knocking on the F-body with stock compression. I always drive to the empty and fill up so it is mostly the octane of the last fill. More knock was observed on 87 than 93 and yes, the SOTP dyno said it screams either way
Never felt any need to scan a 9.5 compression ratio motor for knocks under suspect from burning 87 octane. I occasionally run higher octane gas through it. Zero difference except my wallet is lighter.
Never felt any need to scan a 9.5 compression ratio motor for knocks under suspect from burning 87 octane. I occasionally run higher octane gas through it. Zero difference except my wallet is lighter.
Next time you do, scan it, if you dare. Wait till the tank is empty, fill with 93, drive for a bit and do a few WOT runs and watch the knock count. Repeat with 87 after the 93 is run off and see. On cruising, there is no difference even with a scanner. The difference, if any is seen on heavy loads like WOT.
12-15-2016, 07:43 PM
Hit 150mph in my 1988 C4
