Plans for the L.S.R. Opel GT
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1,580 Posts
very cool Bob a quick look before i go to bed
157 MPH @ 9023 rpm
that's with .39 CF
15 sq. ft of frontal area
11.4 rolling radius
temp 98 deg
100ft alt
humidity 56%
3.90 final drive
90% driveline eff
VE for motor with 121 Cu is 90%
equals 193hp
but need 194hp to get 157mph
davegt27
157 MPH @ 9023 rpm
that's with .39 CF
15 sq. ft of frontal area
11.4 rolling radius
temp 98 deg
100ft alt
humidity 56%
3.90 final drive
90% driveline eff
VE for motor with 121 Cu is 90%
equals 193hp
but need 194hp to get 157mph
davegt27
Sorry if i missed it from your post but exactly what class are you entering, and is there a page where you can get information about the different classes? Also, is the class your entering limited to normal induction? Please keep up updated on this project, its always interesting when one of the opel masters gets serious 
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117 Posts
Bob, with some calculations, you may want to go several inches shorter on your primary header lengths. If you want to make power at about 8800-9000 rpms, you will need to be at about 23" primary length, and this INCLUDES the port length. So figuring about 3" for the average port length, that would give you a pipe length closer to 20".
Swiss
Built lots of bike pipes.
Swiss
Built lots of bike pipes.
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648 Posts
TOO COOL!
Rally Bob,
This is just too cool an idea to comprehend. I remember as a kid reading about all the record setting fun going on at the salt flats. That seemed to fall out of style (or publicity), for a long time. There was an article in GRM a few months back about some top speed events, but I don't remember where it was.
Please keep us all informed on this project.
Jc
Rally Bob,
This is just too cool an idea to comprehend. I remember as a kid reading about all the record setting fun going on at the salt flats. That seemed to fall out of style (or publicity), for a long time. There was an article in GRM a few months back about some top speed events, but I don't remember where it was.
Please keep us all informed on this project.
Jc
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117 Posts
Bob,
You said in an earlier post, "You may have noticed that this engine was built for high rpm power, and not for torque. Many people may assume I'm going to use a 3.18 final drive ratio in the rear axle, and a Getrag with a .805 OD. But with only 3 miles to accelerate to maximum speed, I chose a different philosophy, trying to place the engine's peak power at the projected top speed. To add to this, I'll be trying to accelerate on either salt (Bonneville) or dirt (Muroc and El Mirage). Too much torque wastes time spinning tires. So I'm going to use a 3.90 final drive, with a Quaife close ratio racing tranny (2.25/1.58/1.21/1.00 ratios), and 205/55ZR14 Michelin tires (22.87" tall). "
And then you said, "I'm not looking for a header tuned for maximum power at that rpm though. It's a compromise, looking to fall between peak torque and peak power. It's all about the acceleration through the rpms, not the hp number at the end of the run."
You also mentioned shifting at 9400 rpms and hoping to run through the traps at about 9,000 or so. IF you tune for a compromise between the Torque peak and the Power peak, I don't think that you will pull close to the Power Peak under that kind of speed load. I know that you have to accelerate up from your peak torque number or whatever lower figure that your gearing drops you to with each shift, but without the power near the Peak RPMS that you are pulling for the run, you MAY not be able to pull those rpms/mph. As far as your friend with the track car, And Opels generally need longer tubes anyway...."I used to run 36" tubes on my friend's circle track car...everyone said it was too long, but the power band was broad....5300-8800 rpms with 192 hp with a 2-bbl Holley carb!" His track run is completely different than a top speed attempt. You have to remember that you are de-stroking this engine in order to better run higher rpms, not to enjoy the mid-range power. Mid-range is a nice function for street cars. That is OK, I don't run at Bonneville and you will tune for what you understand anyway.
Swiss
You said in an earlier post, "You may have noticed that this engine was built for high rpm power, and not for torque. Many people may assume I'm going to use a 3.18 final drive ratio in the rear axle, and a Getrag with a .805 OD. But with only 3 miles to accelerate to maximum speed, I chose a different philosophy, trying to place the engine's peak power at the projected top speed. To add to this, I'll be trying to accelerate on either salt (Bonneville) or dirt (Muroc and El Mirage). Too much torque wastes time spinning tires. So I'm going to use a 3.90 final drive, with a Quaife close ratio racing tranny (2.25/1.58/1.21/1.00 ratios), and 205/55ZR14 Michelin tires (22.87" tall). "
And then you said, "I'm not looking for a header tuned for maximum power at that rpm though. It's a compromise, looking to fall between peak torque and peak power. It's all about the acceleration through the rpms, not the hp number at the end of the run."
You also mentioned shifting at 9400 rpms and hoping to run through the traps at about 9,000 or so. IF you tune for a compromise between the Torque peak and the Power peak, I don't think that you will pull close to the Power Peak under that kind of speed load. I know that you have to accelerate up from your peak torque number or whatever lower figure that your gearing drops you to with each shift, but without the power near the Peak RPMS that you are pulling for the run, you MAY not be able to pull those rpms/mph. As far as your friend with the track car, And Opels generally need longer tubes anyway...."I used to run 36" tubes on my friend's circle track car...everyone said it was too long, but the power band was broad....5300-8800 rpms with 192 hp with a 2-bbl Holley carb!" His track run is completely different than a top speed attempt. You have to remember that you are de-stroking this engine in order to better run higher rpms, not to enjoy the mid-range power. Mid-range is a nice function for street cars. That is OK, I don't run at Bonneville and you will tune for what you understand anyway.
Swiss
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1,580 Posts
one thing about the GT its a slippery sucker
i used .39 CF of drag since thats what stock is, but i bet once its lowered it will be less
also using 3.90 gears and no overdrive
i bet if any car can do it a GT can
and Bob Gets my vote for the Opel nut that can put the Gt in the record books
Davegt27
i used .39 CF of drag since thats what stock is, but i bet once its lowered it will be less
also using 3.90 gears and no overdrive
i bet if any car can do it a GT can
and Bob Gets my vote for the Opel nut that can put the Gt in the record books
Davegt27
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730 Posts
I'm impressed with the tech knowledge passing here. Mind-boggling for me. Course, I'm into electronics and consider myself just a notch up from shade-tree mechanic. I'm very interested, like everyone else, to see how this project turns out R.Bob.
first i think saturn is going to beat you with there 900 hp 2.0liter ion that they are setting up to beat the current record of 184
second i figured the impulse was the donor but wasnt sure
and third rallybob i hope you have good suspension mods becaue you know how these cars react to high speed bumps
second i figured the impulse was the donor but wasnt sure
and third rallybob i hope you have good suspension mods becaue you know how these cars react to high speed bumps
Hey Bob, let me know when you're going to Lake Mirage. If I have my GT done by then, knowing it probably won't be this year for either of us, I'll mod my motorcycle trailer and drag my GT behind the motorhome up to watch the fun. And maybe to help with the wrenching, if needed.
Ron
Ron
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2,731 Posts
Bonneville GT is gonna be awesome! I hope it happens.
Bob, over the winter I need to pick your brain some about our new rule changes in the compact class and how to apply them to Speedway GT. One is there will be no camshaft rule. Run ANY cam, and a ruling on my car is if it came factory stock with solid lifters I can use them. Also the stock exhaust manifold rule changed to allowing use of a tubular steel header with primary tubes not running further aft of the bellhousing.
I think only you would know what cam to use...
Sorry to have strayed a bit from your topic but I know your gears are always turning and I respect your wisdom here...
Bob, over the winter I need to pick your brain some about our new rule changes in the compact class and how to apply them to Speedway GT. One is there will be no camshaft rule. Run ANY cam, and a ruling on my car is if it came factory stock with solid lifters I can use them. Also the stock exhaust manifold rule changed to allowing use of a tubular steel header with primary tubes not running further aft of the bellhousing.
I think only you would know what cam to use...
Sorry to have strayed a bit from your topic but I know your gears are always turning and I respect your wisdom here...
Bob, do you have an update on the car...how is it coming. AT $5-8 a tape I would definitly be interested in one If you need help editing I've done quite a bit of digital video editing and would be willing to volunteer some time. If you dont go digital, I wont be able to help...
A bit off topic, but I'm in the middle of making a turbine gokart possible with a lsr attempt in the works (turbine car under 500 lbs). Depending on how long it takes to get the parts rounded up, funding, and where you are with your project i might be able to make it when you go for your attempt with my little project. Good luck.
If you need help editing I've done quite a bit of digital video editing and would be willing to volunteer some time. If you dont go digital, I wont be able to help...A bit off topic, but I'm in the middle of making a turbine gokart possible with a lsr attempt in the works (turbine car under 500 lbs). Depending on how long it takes to get the parts rounded up, funding, and where you are with your project i might be able to make it when you go for your attempt with my little project. Good luck.
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15,436 Posts
My reply to Jeff was moved to here:http://www.opelgt.com/forums/showthread.php?s=&threadid=2120jeff denton said:
Hey Bob I've got a Sony video cam also, with a 16X digital zoom. Maybe I should bring a tripod and set it up on the roof of the motorhome. Knowing how the weather can be in the high desert, I figure maybe you can use the motorhome as a kinda base of operations, I have a 20 ft awning with full screening, and a 10 X 10 popup.
Of course with dual AC. Got to keep the show dogs happy and cool. Margaret has said it is a go, predicated on dog shows in that time frame, whenever it's going to happen. We can run the generator, keep cool and watch the day's events on the TV. And have TV dinners too. It should be a blast. As you get closer, let me know of things I may have you'll need for the attempt. If I clean out the doggy stuff in the rig I should have a fair amount of space available to bring things if needed. Catch ya later,
Ron
Of course with dual AC. Got to keep the show dogs happy and cool. Margaret has said it is a go, predicated on dog shows in that time frame, whenever it's going to happen. We can run the generator, keep cool and watch the day's events on the TV. And have TV dinners
too. It should be a blast. As you get closer, let me know of things I may have you'll need for the attempt. If I clean out the doggy stuff in the rig I should have a fair amount of space available to bring things if needed. Catch ya later,Ron
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