What kind of top speed is your F-body cabable of?
01-15-2008, 11:47 PM
#22
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01-20-2008, 07:24 PM
#25
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Ive had my stockish ws6 upto 160 and I thought the whole thing was going to fall apart from the wind I was hearing and I thought my t tops were going to come flying off. Other then that my bone stock suspension did handle it pretty good and I was on a zrated tire at the time but I wont be doing it again for a while until I get more mods to get up to the speed faster
01-21-2008, 06:33 PM
#26
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Alan Blaine rear spoiler
wickerbill
Lower skirts. You can also see part of the wickerbill
Side skirts before painting
Front air dam
Racing at 165mph. The front end lifts 2" at these speeds. This is before the sideskirts were on the car.
At Nashville Superspeedway @ ~ 125mph with the short track (taller) rear spoiler
01-22-2008, 12:47 PM
#27
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If its just a street chassis that you plan on running at those projected speeds... your best efforts will be spent on ride height, rake... and then on having enough spring and damper to keep it off the bump stops. The ride height and rake will be the best aero adjustments on a stock body. Like I said... depending on any class rules (or lack there of) opens and closes doors on what you can and can not do. No rules = unlimited possibilities and allow you to apply aero mods at will.
My 40+ year old F-Body had run 162mph back in 1991, in its stock form, with no aero mods and an 8.5:1 205hp crate motor. Hopefully... at next years BSW meet... I'll have it near the B/GC record only using a pump gas/NA LSx. One can only hope...
Here are some helpful links towards this train of thought:
Relative Aero Principals
Sumners other ramblings
The Mother of all LSR links
01-24-2008, 11:13 PM
#29
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I guess I should have actually thrown in an answer to the topics actual question...
I have had my hand in a few open road race and LSR chassis over the years and in summation... things start to change right about 170mph... for both third and fourth gen F-bodies. But... the third gens were more aero friendly because of the factory shape of the nose. The Pontiac's dont fair (and have never) as well as their GM brothers either... just for that one reason alone.
Looking at your signature tells me that you have enough power to get to the proposed speeds... but, getting the drivetrain to live under that power and speed can be an issue. To much or too little gear and you can hurt the trans, clutch, fluids, differential etc. But for a short burst... it shouldnt be that much of an issue, really. Its sustaining those speeds that will, obviously, put everything to the test.
On the suspension side of things... I wouldnt use OE control arms or panhard, nor would I want to use a closer to stock spring and damper combination. I should point out that this has more to do with the surface that you will be running on over anything else. Maxton or anything paved... is alot different than that of the salt or the lakes... and the suspension will need to be sprung accordingly to take up for the hard top more than you would think.
Under vessel air flow is your biggest concern... which I pointed out in my first post. Getting the ride height low enough and still maintaining a litte rake is what you need to focus on. Your signature elludes me to beileve that you have put some thought into your components. But, I dont know eactly what you mean by heavy duty... that my be open to interpritation.
I could never overstress the idea of saftey first. If you even think of running that kind of speed... you really need to get some tubes in that car... and think smartly about how you build everything.
Here is our B/GT ride. Its actually an original 68 L88 Tri-Power chassis with factory lake pipes. Its run in the mid 190's for years... and this year, we dropped in a little different engine package. We should get somewhere in the hood of 235-240mph out of it:
My 67 F-body should be close with its new power plant... and we're hoping for about the same MPH as the Y-body. Mind you that both of these cars are street licensed and street legal... in fact, we plan to drive the 67 to the 2009 BSW meet... run it (hopefully get the chassis into the 200mph club)... and then drive it home.
I have had my hand in a few open road race and LSR chassis over the years and in summation... things start to change right about 170mph... for both third and fourth gen F-bodies. But... the third gens were more aero friendly because of the factory shape of the nose. The Pontiac's dont fair (and have never) as well as their GM brothers either... just for that one reason alone.
Looking at your signature tells me that you have enough power to get to the proposed speeds... but, getting the drivetrain to live under that power and speed can be an issue. To much or too little gear and you can hurt the trans, clutch, fluids, differential etc. But for a short burst... it shouldnt be that much of an issue, really. Its sustaining those speeds that will, obviously, put everything to the test.
On the suspension side of things... I wouldnt use OE control arms or panhard, nor would I want to use a closer to stock spring and damper combination. I should point out that this has more to do with the surface that you will be running on over anything else. Maxton or anything paved... is alot different than that of the salt or the lakes... and the suspension will need to be sprung accordingly to take up for the hard top more than you would think.
Under vessel air flow is your biggest concern... which I pointed out in my first post. Getting the ride height low enough and still maintaining a litte rake is what you need to focus on. Your signature elludes me to beileve that you have put some thought into your components. But, I dont know eactly what you mean by heavy duty... that my be open to interpritation.
I could never overstress the idea of saftey first. If you even think of running that kind of speed... you really need to get some tubes in that car... and think smartly about how you build everything.
Here is our B/GT ride. Its actually an original 68 L88 Tri-Power chassis with factory lake pipes. Its run in the mid 190's for years... and this year, we dropped in a little different engine package. We should get somewhere in the hood of 235-240mph out of it:
My 67 F-body should be close with its new power plant... and we're hoping for about the same MPH as the Y-body. Mind you that both of these cars are street licensed and street legal... in fact, we plan to drive the 67 to the 2009 BSW meet... run it (hopefully get the chassis into the 200mph club)... and then drive it home.
Last edited by chicane; 01-24-2008 at 11:30 PM.
01-24-2008, 11:55 PM
#30
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On the suspension side of things...
Under vessel air flow is your biggest concern... which I pointed out in my first post. Getting the ride height low enough and still maintaining a litte rake is what you need to focus on. Your signature elludes me to beileve that you have put some thought into your components. But, I dont know eactly what you mean by heavy duty... that my be open to interpritation.
I could never overstress the idea of saftey first. If you even think of running that kind of speed... you really need to get some tubes in that car... and think smartly about how you build everything.
Some agreement AND disagreement here --speaking from experience.
Lowering the car if you are going to be running at speed on normal highway surfaces is a big NO! My car has been airborne on multiple occasions and my most recent mod was to raise it back up to stock ride height +. Work on keeping the air out from underneath the car and forget about lowering it unless you are going to be on one of those smooth superspeedway tracks. You will drag the exhausts off of it on normal roads at high speed. An innocent dipsy doodle rise in the road will send you airborne for hundreds of feet at 160+.
I do agree wholeheartedly with the safety aspect. Spend your money on cage, fire suppression system, good seats properly mounted and helmet/firesuit/shoes FIRST before you get into the go fast mods.
01-25-2008, 12:45 AM
#31
TECH Fanatic
Good input Andy... its good to see people with some seat time !!
To counter my lack of explaination... then hence my comment of:
I should have however... clairified "low enough" a little bit better.
On a softer sprung chassis... I agree, I wouldnt look at putting it into the weeds. Properly lowering the chassis and utilizing correct spring rates for that will keep you off of the bump stops and launching your car into floatville. That is why I stated... "spring accordingly."
Under vessel (beneath your car) aero has a hugh impact on Cd and stability at speeds above 150mph. Its the inconsistancies in the surface that the spring and damper package help control. If your too low and under sprung... you'll find the bump stops and some air time... with the penalty of increased Cd and loss of stability. On the other hand... a chassis that is set to a lower than factory stock ride height, with the addition of some increased rake... and proper spring rates... will yield a chassis that improves the Cd, has greater stability and will stay off the bump stops.
From my experience... For typical 200mph usage, the spring rates will be in the 800+ range for the front end and somewhere near 225-300 for the rear. An increase in rake will also help with a weak rear spring package, common to that of late models. I use a 720 front with a 320 rear and its solid through "the narrows" (Silver State) at 175+ mph, neutral throttle... but then, its not a forth gen.
Anyway... open road stuff is a totally unpredicatable animal all together. Chassis, driver experience and the willingness to drive to either your limits or that of the car... determines a few ways to approach this. Going through some 'whoops' at speed is definately uncomforting. An easy one to remember... "The spring controls the weight and the damper controls the spring." Once you get past 'aero load'... its all about the spring rate. Just look at the ssbb set ups and how it effects the chassis at speed.
To counter my lack of explaination... then hence my comment of:
I should point out that this has more to do with the surface that you will be running on over anything else. Maxton or anything paved... is alot different than that of the salt or the lakes... and the suspension will need to be sprung accordingly to take up for the hard top more than you would think.
On a softer sprung chassis... I agree, I wouldnt look at putting it into the weeds. Properly lowering the chassis and utilizing correct spring rates for that will keep you off of the bump stops and launching your car into floatville. That is why I stated... "spring accordingly."
Under vessel (beneath your car) aero has a hugh impact on Cd and stability at speeds above 150mph. Its the inconsistancies in the surface that the spring and damper package help control. If your too low and under sprung... you'll find the bump stops and some air time... with the penalty of increased Cd and loss of stability. On the other hand... a chassis that is set to a lower than factory stock ride height, with the addition of some increased rake... and proper spring rates... will yield a chassis that improves the Cd, has greater stability and will stay off the bump stops.
From my experience... For typical 200mph usage, the spring rates will be in the 800+ range for the front end and somewhere near 225-300 for the rear. An increase in rake will also help with a weak rear spring package, common to that of late models. I use a 720 front with a 320 rear and its solid through "the narrows" (Silver State) at 175+ mph, neutral throttle... but then, its not a forth gen.
Anyway... open road stuff is a totally unpredicatable animal all together. Chassis, driver experience and the willingness to drive to either your limits or that of the car... determines a few ways to approach this. Going through some 'whoops' at speed is definately uncomforting. An easy one to remember... "The spring controls the weight and the damper controls the spring." Once you get past 'aero load'... its all about the spring rate. Just look at the ssbb set ups and how it effects the chassis at speed.
01-25-2008, 07:37 AM
#32
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02-01-2008, 06:14 PM
#33
[QUOTE=chicane;8563552]I guess I should have actually thrown in an answer to the topics actual question...
I have had my hand in a few open road race and LSR chassis over the years and in summation... things start to change right about 170mph... for both third and fourth gen F-bodies. But... the third gens were more aero friendly because of the factory shape of the nose. The Pontiac's dont fair (and have never) as well as their GM brothers either... just for that one reason alone.
Looking at your signature tells me that you have enough power to get to the proposed speeds... but, getting the drivetrain to live under that power and speed can be an issue. To much or too little gear and you can hurt the trans, clutch, fluids, differential etc. But for a short burst... it shouldnt be that much of an issue, really. Its sustaining those speeds that will, obviously, put everything to the test.
On the suspension side of things... I wouldnt use OE control arms or panhard, nor would I want to use a closer to stock spring and damper combination. I should point out that this has more to do with the surface that you will be running on over anything else. Maxton or anything paved... is alot different than that of the salt or the lakes... and the suspension will need to be sprung accordingly to take up for the hard top more than you would think.
Under vessel air flow is your biggest concern... which I pointed out in my first post. Getting the ride height low enough and still maintaining a litte rake is what you need to focus on. Your signature elludes me to beileve that you have put some thought into your components. But, I dont know eactly what you mean by heavy duty... that my be open to interpritation.
I could never overstress the idea of saftey first. If you even think of running that kind of speed... you really need to get some tubes in that car... and think smartly about how you build everything.
Thanks Chicane and AndyJ,
Good information. Post was geared towards stock style suspension and deficiencies in the 4th gen TA body at speed. My suspension components are all thick walled tubular pieces (but stock geometry) so robustness and deflection in the those parts shouldn't be an issue. I don't have a good grasp on spring rates that would be needed for runnning at speed for a few miles at a shot. hitting a depression in the road without bottoming out the suspension is a concern. Would I expect to have to increase the spring rate by 3 fold going from 75 mph to 200 mph when on a good asphalt road with regular imperfections? How about going to salt vs. the 'good' asphalt road.
Having a car that darts or is flighty at speed is another concern. The car already sits very low. On this body style, is a large air dam and keeping air from under the vehicle absolutely nessesary to maintain aerodynamic stability? I noticed that your Corvette doesn't an air dam upfront. I don't have an absolute bogey on top speed. If the vehicle is stable at 200 during an open road event, that would be fine. What ever it is safely capable of is that answer. If I need to further refine the body..dams or spoilers, that is also fine.
Power train, chassis rigidty, Engine durability, and safety have already been addressed. This is tube chassis car inside of a stock body. I am primarily a drag racer but have road raced, and ran 2 open road events in the 90's. this is just a little faster than what I have experienced in the past.
Thanks again
I have had my hand in a few open road race and LSR chassis over the years and in summation... things start to change right about 170mph... for both third and fourth gen F-bodies. But... the third gens were more aero friendly because of the factory shape of the nose. The Pontiac's dont fair (and have never) as well as their GM brothers either... just for that one reason alone.
Looking at your signature tells me that you have enough power to get to the proposed speeds... but, getting the drivetrain to live under that power and speed can be an issue. To much or too little gear and you can hurt the trans, clutch, fluids, differential etc. But for a short burst... it shouldnt be that much of an issue, really. Its sustaining those speeds that will, obviously, put everything to the test.
On the suspension side of things... I wouldnt use OE control arms or panhard, nor would I want to use a closer to stock spring and damper combination. I should point out that this has more to do with the surface that you will be running on over anything else. Maxton or anything paved... is alot different than that of the salt or the lakes... and the suspension will need to be sprung accordingly to take up for the hard top more than you would think.
Under vessel air flow is your biggest concern... which I pointed out in my first post. Getting the ride height low enough and still maintaining a litte rake is what you need to focus on. Your signature elludes me to beileve that you have put some thought into your components. But, I dont know eactly what you mean by heavy duty... that my be open to interpritation.
I could never overstress the idea of saftey first. If you even think of running that kind of speed... you really need to get some tubes in that car... and think smartly about how you build everything.
Thanks Chicane and AndyJ,
Good information. Post was geared towards stock style suspension and deficiencies in the 4th gen TA body at speed. My suspension components are all thick walled tubular pieces (but stock geometry) so robustness and deflection in the those parts shouldn't be an issue. I don't have a good grasp on spring rates that would be needed for runnning at speed for a few miles at a shot. hitting a depression in the road without bottoming out the suspension is a concern. Would I expect to have to increase the spring rate by 3 fold going from 75 mph to 200 mph when on a good asphalt road with regular imperfections? How about going to salt vs. the 'good' asphalt road.
Having a car that darts or is flighty at speed is another concern. The car already sits very low. On this body style, is a large air dam and keeping air from under the vehicle absolutely nessesary to maintain aerodynamic stability? I noticed that your Corvette doesn't an air dam upfront. I don't have an absolute bogey on top speed. If the vehicle is stable at 200 during an open road event, that would be fine. What ever it is safely capable of is that answer. If I need to further refine the body..dams or spoilers, that is also fine.
Power train, chassis rigidty, Engine durability, and safety have already been addressed. This is tube chassis car inside of a stock body. I am primarily a drag racer but have road raced, and ran 2 open road events in the 90's. this is just a little faster than what I have experienced in the past.
Thanks again
02-01-2008, 10:25 PM
#34
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Originally Posted by TT632
I don't have a good grasp on spring rates that would be needed for runnning at speed for a few miles at a shot. hitting a depression in the road without bottoming out the suspension is a concern. Would I expect to have to increase the spring rate by 3 fold going from 75 mph to 200 mph when on a good asphalt road with regular imperfections? How about going to salt vs. the 'good' asphalt road.
This was on a suspension that had been lowered 1.5" with Koni DA shocks at all 4 corners and Hotchkis springs. I raised the car back to stock ride height over the winter and added a custom set of Unbalanced Engineering Coilovers and Bilstein custom valved race shocks. I added a larger front air dam and side skirts. It is all about keeping the air out from underneath the car--you still need the ground clearance for suspension travel on a 4th Gen. Again, experience speaking, not hypotheses or something I have read etc.
BTW, the collective brain trust on road racing is present over on the FRRAX board. Alot more of those members that have been there and done that. It may serve you well to spend some time reading the huge amount of info contained in the archives threads there.
Maybe it is just me but there is no way I would take a new vehicle out for a shakedown in any class above 130 in ORR.... even if you are an experienced driver. A friend of mine who has driven in a dozen or more Texas ORR's all the way up to Unlimited recently entered a new to him 4th gen. He participated in the 110mph class
My .02. Per participant, ORR is one of the most dangerous racing venues in the world and the equipment driven at speed needs to be sorted well.
02-01-2008, 11:15 PM
#36
FormerVendor
I ran my 96 at the hot rod top speed challenge, 199.4 in the standing mile. Body is completely stock. Felt very stable but the front end felt like it was lifting alot.
02-16-2008, 07:03 PM
#37
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you could do like the nascars do to gain down force as you speed up use really soft springs and a good sway bar the faster you go the lower the car gets but they also have height requirements to its a way of cheating i guess
