How do you keep the C3 from getting light above 120mph?
04-24-2012, 02:58 PM
#1
Race Director
Thread Starter
How do you keep the C3 from getting light above 120mph?
Well that's the question... I have the following mods for suspention but above 120 I can still feel her starting to get light, and at arond 160 it's just not good.... So here are the mods:
I am between 3-4" off the ground from frame or exhaust. #550 front springs cut 1/2 coil, bilstine sport shocks, #360 rear carbon fibor spring, spreader bar, tires and wheels rated for such speeds... Large front and rear sway bars, rack and pinion...so for just suspention that is what I have.
I think I'm not letting enough air escape from under the hood,,,, I saw Beejay install hood vents, so I think that that will be my next mod.... Any other ideas? Thx
I am between 3-4" off the ground from frame or exhaust. #550 front springs cut 1/2 coil, bilstine sport shocks, #360 rear carbon fibor spring, spreader bar, tires and wheels rated for such speeds... Large front and rear sway bars, rack and pinion...so for just suspention that is what I have.
I think I'm not letting enough air escape from under the hood,,,, I saw Beejay install hood vents, so I think that that will be my next mod.... Any other ideas? Thx
Last edited by pauldana; 03-12-2013 at 05:05 PM.
Popular Reply
05-17-2017, 10:43 PM
Le Mans Master
OK. "Speed kills!", to recite the old adage. (More often, it's those sudden unplanned stops.) I believe there is likely a clear consensus among this thread's followers that your point has most assuredly been made, sir.
So, let's p l e a s e allow the discussion to get back onto the OP's topic, as his original inquiry wasn't made to induce such judgement calls. Anyway, the subject matter being discussed prior to the finger of condemnation being wagged at those of us who are interested remains a perfectly valid technical one, particularly from the perspective of on-track performance.
Show of hands, how many complete morons here?
Any?
None. That's what I thought.
Thank you.
/Charlie
So, let's p l e a s e allow the discussion to get back onto the OP's topic, as his original inquiry wasn't made to induce such judgement calls. Anyway, the subject matter being discussed prior to the finger of condemnation being wagged at those of us who are interested remains a perfectly valid technical one, particularly from the perspective of on-track performance.
Show of hands, how many complete morons here?
Any?
None. That's what I thought.
Thank you.
/Charlie
04-24-2012, 03:27 PM
#3
Burning Brakes
Do you have the pace car front spoiler? Look into keeping as much air out from underneath the car as possible. I have a custom splitter that is 3" off the ground which I think helps immensely at high speed.
04-24-2012, 03:28 PM
#4
Melting Slicks
Well that's the question... I have the following mods for suspention but above 120 I can still feel her starting to get light, and at arond 160 it's just not good.... So here are the mods:
I am between 3-4" off the ground from frame or exhaust. #550 front springs cut 1/2 coil, bilstine sport shocks, #360 rear carbon fibor spring, spreader bar, tires and wheels rated for such speeds... Large front and rear sway bars, rack and pinion...so for just suspention that is what I have.
I think I'm not letting enough air escape from under the hood,,,, I saw Beejay install hood vents, so I think that that will be my next mod.... Any other ideas? Thx
I am between 3-4" off the ground from frame or exhaust. #550 front springs cut 1/2 coil, bilstine sport shocks, #360 rear carbon fibor spring, spreader bar, tires and wheels rated for such speeds... Large front and rear sway bars, rack and pinion...so for just suspention that is what I have.
I think I'm not letting enough air escape from under the hood,,,, I saw Beejay install hood vents, so I think that that will be my next mod.... Any other ideas? Thx
04-24-2012, 03:52 PM
#6
alignment both front and rear set for high speed track?
http://www.vbandp.com/View-document-...ent-Specs.html
http://www.vbandp.com/View-document-...ent-Specs.html
Last edited by MelWff; 04-24-2012 at 03:55 PM.
04-24-2012, 03:56 PM
#7
Race Director
Thread Starter
I have he front stock air dam and the stick rear spoiler
Yes again... Stock front air dam
Got a pic of your custom splitter? What speed have you had it to? Any difference? I can't go much lower with out hitting small stOnes in the road!!!
Sorry, my bad.... Fiberglass trw 360 spring
Got a pic of your custom splitter? What speed have you had it to? Any difference? I can't go much lower with out hitting small stOnes in the road!!!
Sorry, my bad.... Fiberglass trw 360 spring
04-24-2012, 05:38 PM
#8
Burning Brakes
Look at BeeJays custom Pace car spoiler. I would say his looks the best and is probably the most functional.
Here is mine... The aluminum support rods are "consumables" but the fiberglass will flex enough if you scrape a driveway. The only reason I have scraped my splitter/bent a support rod is because I was forced to enter a driveway at a less than optimal approach angle or I wasnt paying attention and hit a HUGE pot hole. Most speedbumps are no taller than 3" and if they are, they are the speed "humps" that span a further distance so I still wont scrape.
04-24-2012, 06:04 PM
#10
Your wheel alignment, tires, and all wheel bearings and suspensinon components need to be absolutely spot on perfect.
Then you might begin to look at aero mods.
Remember the C3 was not designed to a low drag coefficient. It was designed to "look cool''. (And, we might all agree, succeeded). I believe the early C3's had a Cd of something like .5. The '80 to '82 cars were slightly better, like .45. Whereas a C5 or C6 has a Cd of perhaps .3 or even slightly less. So the new cars are about 40% better, as far as aero drag is concerned..
Then you might begin to look at aero mods.
Remember the C3 was not designed to a low drag coefficient. It was designed to "look cool''. (And, we might all agree, succeeded). I believe the early C3's had a Cd of something like .5. The '80 to '82 cars were slightly better, like .45. Whereas a C5 or C6 has a Cd of perhaps .3 or even slightly less. So the new cars are about 40% better, as far as aero drag is concerned..
04-24-2012, 06:34 PM
#12
Team Owner
When I had a stock 79 nose I added 3-4 inches to the front chin spooler just using 6 inch wide black rubber floor molding from the hardware store like Home Depot I drilled holes and used big rivots, but anyway bolts and large washers would work. I had 550 front springs and used 255/45/17 front tires which are 25.7 or so diameter. The extra chin make more vacuum under the car at speed.
The second thing is rake. Measure each rear center of the fender well hieght. then crank on the rear spring end bolts lifting the rear in 1/2 inch increments and test how stable it is. The higher rear points the nose down and makes for more front downforce
One problem about our c-3's is that the steering is tooooooo fast. you need higher ratios for higher speed.
The second thing is rake. Measure each rear center of the fender well hieght. then crank on the rear spring end bolts lifting the rear in 1/2 inch increments and test how stable it is. The higher rear points the nose down and makes for more front downforce
One problem about our c-3's is that the steering is tooooooo fast. you need higher ratios for higher speed.
Last edited by gkull; 04-24-2012 at 06:37 PM.
04-24-2012, 09:11 PM
#14
Race Director
There has been lots of discussion on this. Do a search on this forum using "aero".
This will get you started. Look at post #5 in particular.
http://forums.corvetteforum.com/c3-t...ics-et-al.html
This will get you started. Look at post #5 in particular.
http://forums.corvetteforum.com/c3-t...ics-et-al.html
Last edited by 3JsVette; 04-24-2012 at 10:40 PM.
Please be careful. PS, How is the A/C?
04-24-2012, 10:22 PM
#16
Le Mans Master
Having downforce rather than lift is all about having more air pressure above than below the body, and there are some fairly straight forward steps that can get you closer to being on the right side of that equation. FWIW, it doesn't take much to make a significant difference, as only 0.1 PSI Δ (differential) on 20 sq.ft. yields 288# of lift or downforce.
1) For pre-'80 bodywork, adding a functional front dam and rear spoiler helps a lot, and the Pace Car kit actually works, but IMOE the dam needs bracing and/or a splitter for very much high speed running.
2) Lower ride heights (assuming you're not already at or near Power Book recommendations). Agree with George about ~1/2" rake, but keep in mind it's not something you want to take too far.
3) Properly sealed hood, CAI or not. At speed there is a high pressure area at the base of the windshield which you don't want bleeding under the rear of the hood into the engine compartment.
There is, of course, more that can be done, but I wouldn't worry about things such as fenderwell vents, diffusers, belly pans, wings, dive plates or undercarriage streamlining until and unless the above doesn't suffice. These guys apparently weren't satisfied with only doing the basics...
1) For pre-'80 bodywork, adding a functional front dam and rear spoiler helps a lot, and the Pace Car kit actually works, but IMOE the dam needs bracing and/or a splitter for very much high speed running.
2) Lower ride heights (assuming you're not already at or near Power Book recommendations). Agree with George about ~1/2" rake, but keep in mind it's not something you want to take too far.
3) Properly sealed hood, CAI or not. At speed there is a high pressure area at the base of the windshield which you don't want bleeding under the rear of the hood into the engine compartment.
There is, of course, more that can be done, but I wouldn't worry about things such as fenderwell vents, diffusers, belly pans, wings, dive plates or undercarriage streamlining until and unless the above doesn't suffice. These guys apparently weren't satisfied with only doing the basics...
04-24-2012, 11:26 PM
#17
Race Director
Thread Starter
alignment both front and rear set for high speed track?
http://www.vbandp.com/View-document-...ent-Specs.html
http://www.vbandp.com/View-document-...ent-Specs.html
Most all those guys are now C5&6's..... they never see me coming!!
Ive hit 130 on the road course (no more gear left) But I can say there is a big difference compared to nothing.
Look at BeeJays custom Pace car spoiler. I would say his looks the best and is probably the most functional.
Here is mine... The aluminum support rods are "consumables" but the fiberglass will flex enough if you scrape a driveway. The only reason I have scraped my splitter/bent a support rod is because I was forced to enter a driveway at a less than optimal approach angle or I wasnt paying attention and hit a HUGE pot hole. Most speedbumps are no taller than 3" and if they are, they are the speed "humps" that span a further distance so I still wont scrape.
Look at BeeJays custom Pace car spoiler. I would say his looks the best and is probably the most functional.
Here is mine... The aluminum support rods are "consumables" but the fiberglass will flex enough if you scrape a driveway. The only reason I have scraped my splitter/bent a support rod is because I was forced to enter a driveway at a less than optimal approach angle or I wasnt paying attention and hit a HUGE pot hole. Most speedbumps are no taller than 3" and if they are, they are the speed "humps" that span a further distance so I still wont scrape.
1. Your wheel alignment, tires, and all wheel bearings and suspensinon components need to be absolutely spot on perfect.
Then you might begin to look at aero mods.
2. Remember the C3 was not designed to a low drag coefficient. It was designed to "look cool''. (And, we might all agree, succeeded). I believe the early C3's had a Cd of something like .5. The '80 to '82 cars were slightly better, like .45. Whereas a C5 or C6 has a Cd of perhaps .3 or even slightly less. So the new cars are about 40% better, as far as aero drag is concerned..
Then you might begin to look at aero mods.
2. Remember the C3 was not designed to a low drag coefficient. It was designed to "look cool''. (And, we might all agree, succeeded). I believe the early C3's had a Cd of something like .5. The '80 to '82 cars were slightly better, like .45. Whereas a C5 or C6 has a Cd of perhaps .3 or even slightly less. So the new cars are about 40% better, as far as aero drag is concerned..
Here are the numbers again ...http://i237.photobucket.com/albums/f...8new/aero3.jpg
2. part of my problem now
1. When I had a stock 79 nose I added 3-4 inches to the front chin spooler just using 6 inch wide black rubber floor molding from the hardware store like Home Depot I drilled holes and used big rivots, but anyway bolts and large washers would work. I had 550 front springs and used 255/45/17 front tires which are 25.7 or so diameter. The extra chin make more vacuum under the car at speed.
2. The second thing is rake. Measure each rear center of the fender well hieght. then crank on the rear spring end bolts lifting the rear in 1/2 inch increments and test how stable it is. The higher rear points the nose down and makes for more front downforce
3. One problem about our c-3's is that the steering is tooooooo fast. you need higher ratios for higher speed.
2. The second thing is rake. Measure each rear center of the fender well hieght. then crank on the rear spring end bolts lifting the rear in 1/2 inch increments and test how stable it is. The higher rear points the nose down and makes for more front downforce
3. One problem about our c-3's is that the steering is tooooooo fast. you need higher ratios for higher speed.
2. 550 here also cut 1/2 coil. front 245/45zr18 rear 275/40zr18 my front wheel well hight is 26 1/2" front, 27 1/4" back
3. i have rack and pinion, but yes, much to twitchy still
Been racing Willow springs small track, and on the straight away im hitting a brief speed of 110+ before into hard breaking. I going to be more on the big track now, and the speeds are much greater.
There has been lots of discussion on this. Do a search on this forum using "aero".
This will get you started. Look at post #5 in particular.
http://forums.corvetteforum.com/c3-t...ics-et-al.html
This will get you started. Look at post #5 in particular.
http://forums.corvetteforum.com/c3-t...ics-et-al.html
Having downforce rather than lift is all about having more air pressure above than below the body, and there are some fairly straight forward steps that can get you closer to being on the right side of that equation. FWIW, it doesn't take much to make a significant difference, as only 0.1 PSI Δ (differential) on 20 sq.ft. yields 288# of lift or downforce.
1) For pre-'80 bodywork, adding a functional front dam and rear spoiler helps a lot, and the Pace Car kit actually works, but IMOE the dam needs bracing and/or a splitter for very much high speed running.
2) Lower ride heights (assuming you're not already at or near Power Book recommendations). Agree with George about ~1/2" rake, but keep in mind it's not something you want to take too far.
3) Properly sealed hood, CAI or not. At speed there is a high pressure area at the base of the windshield which you don't want bleeding under the rear of the hood into the engine compartment.
There is, of course, more that can be done, but I wouldn't worry about things such as fenderwell vents, diffusers, belly pans, wings, dive plates or undercarriage streamlining until and unless the above doesn't suffice. These guys apparently weren't satisfied with only doing the basics...
1) For pre-'80 bodywork, adding a functional front dam and rear spoiler helps a lot, and the Pace Car kit actually works, but IMOE the dam needs bracing and/or a splitter for very much high speed running.
2) Lower ride heights (assuming you're not already at or near Power Book recommendations). Agree with George about ~1/2" rake, but keep in mind it's not something you want to take too far.
3) Properly sealed hood, CAI or not. At speed there is a high pressure area at the base of the windshield which you don't want bleeding under the rear of the hood into the engine compartment.
There is, of course, more that can be done, but I wouldn't worry about things such as fenderwell vents, diffusers, belly pans, wings, dive plates or undercarriage streamlining until and unless the above doesn't suffice. These guys apparently weren't satisfied with only doing the basics...
AC needs 1 more can of freon, but it is working now, thank you again!!!!
my frame crossmember is at ~3".... cant go much lower.
Sealed hood??????? really?????? i was thinking of venting it!! ...... im confused... i want to release the pressure build up dont i??
04-24-2012, 11:36 PM
#18
Safety Car
Member Since: Nov 2005
Location: Lompoc, CA. Santa Barbara County
Posts: 3,932
Received 543 Likes
on
198 Posts
Venting my hood made a huge difference in front end feel and steering responsiveness at ultra high speeds. Venting the hood also helped drop the radiator temps too. I have a 170 degree thermostat and I rarely get up to that temp. Also, I made a splitter that seems pretty effective. I made it out of plywood, but I need to find another material.
Bee Jay
Bee Jay
Last edited by Bee Jay; 04-25-2012 at 12:10 AM.
04-24-2012, 11:56 PM
#20
Le Mans Master
Pressures differentials from above to beneath the hood vary, and you want to make sure you don't open anything up where pressure above is greater than that directly beneath any specific location. So it depends on where you intend to vent as to whether or not it would prove beneficial. Other than for isolated CAI, I'd look elsewhere than at the cowl just ahead of the windshield. Besides, in city traffic the lack of a rear hood seal invites hot engine compartment air into the cabin.
FWIW, tho I've studied up on this stuff a bit, I don't have a sheepskin in the subject, but if I can ever afford to get my shark back in service I do have instrumentation on hand with which to gather supportive data. (Donations to the cause graciously accepted. )
FWIW, tho I've studied up on this stuff a bit, I don't have a sheepskin in the subject, but if I can ever afford to get my shark back in service I do have instrumentation on hand with which to gather supportive data. (Donations to the cause graciously accepted.
)
Last edited by TheSkunkWorks; 04-24-2012 at 11:58 PM.
