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Learning how to build Lotus Seven replicas...together!
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PostPosted: Mon Apr 09, 2012 4:51 am 
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Location: Laramie WY
This Is My First Build List For The Rotus 7. Frame Will Be Built By End Of April. Lots Of ??? To Answer And Blanks To Fill In. Please Help Fill In Gaps Or Educate Me Where I'm Completely Wrong. Going For A Modern And Retro Look With Some Sort Of Rotary Theme .

Tri Rotor 20B Turbo 600-650hp Goal

Big Single Turbo. 80mm??? 88mm??? Bigger???

Peripheral Or Bridge Port On Motor??? Half Or Full???

Mustang II Front Suspension??? Spitfire Rack And Pinion???

3 Link Rear Suspension. (Watts maybe???)

87 Toyota Pickup Rear End??? W/ Locker Or Limited Slip Of Some Sort

6speed Trans (Possibly 5speed)

Fiberglass Or Carbon Body Panels

Waterproof Race Buckets W/ 5pt Harness

Wilwood Lightweight Rotors. 11-13"??? 4 Or 6 Piston???

Pearl Metallic Flue Green (Lamborghini Green). Black accents???

16in Wheels. 8"Rear??? 6" Fronts??? Black??? Black Chrome??? Black And Body Color??? BBS??? Lightweight???

Aluminum or Carbon Drive Shaft

Aluminum Water Pump

15-20gal Fuel Cell

Double or triple plate clutch

Lithium Battery 5lbs

Retro Parts (Shifter, Dash, Gauges, Floor Hinged Pedals) Need Retro Ideas

Fenders And Body (Original Look Or Modern)

Rotary Exhaust??? What Sounds Good???

Electronic Cutouts After Headers.

Turn Into Coupe Or How To Make A Hardtop??

HID Headlights. Modern Or Retro Look???

Rotar shaped front grille opening


Last edited by Shortexistence on Mon Apr 09, 2012 8:40 pm, edited 1 time in total.

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PostPosted: Mon Apr 09, 2012 6:54 pm 
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Got the frame started today halfway through class. It's going to be a full round tube frame 1"x.120. I got the first few bends done before the end of the day and will be working on it until graduation on April 20th. I'll have pictures up when it starts looking like something other than a couple of bent tubes.


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PostPosted: Mon Apr 09, 2012 11:46 pm 
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I would say try the car without the turbo first to get it sorted.

The trip rotor will really surprise you especially when coupled to this low of a weight vehicle.

Also that way you are not working on all the problems at once. Get the chassis sorted and then throw more horsepower than God needs at it.

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PostPosted: Tue Apr 10, 2012 12:41 am 
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Thanks for the advice. The concept of this car is only 4 months old for me and I'm here to learn. Because of money the engine won't be thrown in making end goal horsepower, not even close to it. There's a lot that goes into tuning a chassis and building a car from scratch. This is going to be a slow build that gets done right and as the money comes to it. The power may be obscene but that's sort of the point for me.


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PostPosted: Tue Apr 10, 2012 1:17 am 
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Ambition is great, but your moving a little fast. If you're still in school you could give yourself a homework problem and try to figure out how fast you would need to go to be able to use 600 HP without spinning the rear wheels. :shock:

That's really thick wall tubing you're using. We usually build with 16 gauge, .065". Your tubing is twice as thick so twice as strong. If you used 2" tubing that was .065" then it would be 8 times as stiff as the 1" tubing we normally use and it would be the same weight as your tubing.

I don't have a calculator but I think that 1.25" x .065" tubing would be as strong as what your using for bending and twisting. Those are usually the bigger issues.

Don't give up, this is a big education for all of us!

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PostPosted: Tue Apr 10, 2012 8:28 am 
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Yo, "Shorty"...

You just knew somebody would call you that, right? OK, I'm done now...

Actually, the best advice has already been given to you. Think about that frame tubing, what you're proposing is going to be quite heavy. One of the builders in here went with .120 wall tubing and at some point conceded that it was way heavier than he needed. Nothing wrong with using it, exactly, just overkill.

And again, like Carguy said, build the engine up to some "normal" level, stock hp output, even. Drive the car and sort out the suspension and train the driver before you go to atomic levels of power. You may find that you're totally satisfied with the power (and/or you'll scare yourself sh*tless) and don't need as much motor as you think. Or not...

In your list, you noted Mustang II front suspension. Good choice. You also noted Spitfire steering rack. Good choice... But, why not go with a Mustang II rack as well, and know it'll fit to begin with. Nothing wrong with a Spitfire rack, I'm just voting for keeping things simple.

If you do some research in here, you can find examples of floor-mounted pedals, retro dash and gauges, and various kinds of seats and rear axles. I know you got plenty of homework from your "real" school, but if you do a little homework in here, you can find what you're looking for. Oh, and about that exhaust, "What sounds good with a rotary?"-- My answer is "Turn the ignition off!" But that's just my l'il opinion. You'll hear from a guy named Chuck shortly, now that I've said that... Heehee...

Oh, and Welcome to the Forum!
:cheers:
JD Kemp

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Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom


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PostPosted: Tue Apr 10, 2012 9:42 am 
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GonzoRacer wrote:
Oh, and about that exhaust, "What sounds good with a rotary?"-- My answer is "Turn the ignition off!"
JD Kemp



The 20b sounds the closest to a Ferrari V12 of any other non V12 engine. OF COURSE IT'S LOUDER, but it has a very nice and distinctive sound.

It will take a LOT of muffler so don't even think of trying to get away with a glass pack or anything similar.

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PostPosted: Tue Apr 10, 2012 9:56 am 
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You'll hear from a guy named Chuck shortly, now that I've said that... Heehee...


Thank you, Thank you very much!

Welcome to the club Shortexistance....

To begin with, in order to get a good set of responses, you should state your end goal and budget. Race ready? Road course or ¼ mile? What class will you compete in? Will it be a street car? What state will you register in? You have a budget of $5K , $20K or $50K? What is your age? If under 25, or have no other daily driver, you may have problems getting insurance from the Grundy’s and Hagerty’s of the world. Normal insurance companies most likely will not touch it with a 10 ft pole, especially if you go with a modern exo-body style. What prior mechanical/fab experience do you have? Do you have your own machine shop or will you be farming out the machine work. Trying to stay with off the shelf mechanicals or willing to roll your own? These all help us to focus on your car.

I know nothing more about the rotary other than I built my Locost using one. It is a bone stock '91 N/A keg so not much to talk about for a rotor head. I rebuilt my engine and Megasquirted it. However, you seem to be all over the map with your engine choices. There is a big difference in peripheral port vs a half bridge port. Have you ridden in a moderately powered Locost? One in the 150-250 HP range is insanely fast. I suggest you do so before you get too far down the build path. And remember that a passenger adds 10% to the total weight of the vehicle, so it will go even quicker when you are driving it alone. there are af ew builders here with rotaries and some with turbos. I can't think of a 3-rotor turbo powered Locost here. If you decide to continue down that path, you maybe the first.

Keeping these rotary engines quiet can be another challenge. From what I have heard, the turbos help to quiet things down quite a bit. I can’t speak to that. Big engines in small cars are tough to tame. There are few options considering the space required in a traditional Locost for enough muffler volume. A presilencer and a huge turbo muffler “might” work with a turbo. I did that on my N/A and it was still way too noisey. Especially for a passenger. The exit for the exhaust is about 2 ft away from their ears! I had to restrict the exhaust pipe in order to get some reasonable level of sound. It is still loud to my ancient failing ears. Still, many have congratulated me on how tame the rotary sounds. I am planning on a change for better volume control but haven't done any more work in that area yet. Having some way to get the exhaust to the back end of the car for a 2nd muffler or some pipe volume might help.

If you aren’t familiar with the various mods you are talking about, my best suggestion is to spend some time over on rx7club.com. They don’t much about 1300# cars, but do know the rotary pretty well.

Based on your original list of goals. I would say you have a long row to hoe. I'll let the others comment more.

And again, welcome
Chuck

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“Any suspension will work if you don’t let it.” - Colin Chapman

Check out my rotary build log: click here


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PostPosted: Tue Apr 10, 2012 11:07 am 
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Tri Rotor 20B Turbo 600-650hp Goal

Lowboost setting should see 900 at least


Big Single Turbo. 80mm??? 88mm??? Bigger???

Triple rotor = triple 90’s for sure


Peripheral Or Bridge Port On Motor??? Half Or Full???

Use both with switching valves for high speed and super high speed


Mustang II Front Suspension??? Spitfire Rack And Pinion???

70 Trans-Am Mustang front end for the win


3 Link Rear Suspension. (Watts maybe???)

Porsche 917/30 transaxle and IRS


87 Toyota Pickup Rear End??? W/ Locker Or Limited Slip Of Some Sort

Ford F350 full floater with Detroit Locker


6speed Trans (Possibly 5speed)

13 speed Roadranger (has overdrive top)


Fiberglass Or Carbon Body Panels

Titanium fibre’d carbon


Waterproof Race Buckets W/ 5pt Harness

F/A-18E/F Super Hornet seats (with ejector option)


Wilwood Lightweight Rotors. 11-13"??? 4 Or 6 Piston???

18” carbon fibre with 8 piston magnesium calipers


Pearl Metallic Flue Green (Lamborghini Green). Black accents???

Flames


16in Wheels. 8"Rear??? 6" Fronts??? Black??? Black Chrome??? Black And Body Color??? BBS??? Lightweight???

24 x 375’s all around


Aluminum or Carbon Drive Shaft

Titanium with ceramic universal bearings


Aluminum Water Pump

Titanium


15-20gal Fuel Cell

Should be good for startup and once around the block to warm the engine but what about a fuel tank for driving?


Double or triple plate clutch

9 plate wet clutch


Lithium Battery 5lbs

Lithium polymer 4lbs


Fenders And Body (Original Look Or Modern)

Roswell UFO shape


Rotary Exhaust??? What Sounds Good???

A Chev LS7


Turn Into Coupe Or How To Make A Hardtop??

Put a helmet on


Electronic Cutouts After Headers.

I think they are already installed


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PostPosted: Tue Apr 10, 2012 11:30 am 
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Quote:
87 Toyota Pickup Rear End??? W/ Locker Or Limited Slip Of Some Sort
Ford F350 full floater with Detroit Locker


6speed Trans (Possibly 5speed)
13 speed Roadranger (has overdrive top)


Fiberglass Or Carbon Body Panels
Titanium fibre’d carbon


Waterproof Race Buckets W/ 5pt Harness
F/A-18E/F Super Hornet seats (with ejector option)


Wilwood Lightweight Rotors. 11-13"??? 4 Or 6 Piston???
18” carbon fibre with 8 piston magnesium calipers


Pearl Metallic Flue Green (Lamborghini Green). Black accents???
Flames


Cheapracer, you been into some of those "ancient mystic Chinese potions" again? (AND DIDN'T SHARE!?!?!?) DAMMIT!!!
:rofl:

:cheers:
JDK

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom


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PostPosted: Tue Apr 10, 2012 11:53 am 
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if you aren't careful you will have someone's eye out with that.

have you ever driven a car at or above 100mph and had to slow down for a bend, cos if you haven't stop right now and think.

speed is something you need to creep up on, or it will bite you in the arse and you might not walk away.

home building a car with the performance of a le mans prototype is not for the uninitiated, as well as being down right dangerous, think about what you can handle, think about how you will overcome the challenges of building a car, any car before you jump in feet first.

if you build what you are saying, call me before you drive it so i can make sure i am in another state at the time.

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drag racers lament

oh to go down to the strip again where the blacktop meets the sky
all i ask is a small block and some fuel to make her fly
with slicks a smokin pushrods pokin next round i'll get a bye

she's up on song the shift was strong in the finals to boot
it's back to the pits and take it to bits and don't forget the shute
the final round was good and sound so come on give me the loot


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PostPosted: Tue Apr 10, 2012 1:24 pm 
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Yessss..

150hp in these cars is fast, 300hp is insane, 600hp? you better have life insurance. At 600 hp you are closing in on F1 car power to weight. This is not an F1 car. That being said, there is a Locost out there with around 600hp.

http://www.youtube.com/watch?v=RWn3pkrE ... re=channel

With a little better traction it could get into the high 8's

Look at the performance of a Caterham R500. "Only" 260 hp

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PostPosted: Tue Apr 10, 2012 3:10 pm 
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bremms wrote:

150hp in these cars is fast, 300hp is insane,


Indeed.

I feel sorry for people with genuine big hp cars, they can seldom use them other than barely controllable, short acceleration bursts.

200 to 250hp in 600 to 700kgs (1300/1500lbs) can bring some unbelievable (but controllable) thrills and 150 to 200hp can scare the pants off most people.


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PostPosted: Tue Apr 10, 2012 3:34 pm 
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Quote:
Too much of a good thing can be just wonderful.
-- Mae West

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom


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PostPosted: Wed Apr 11, 2012 4:36 am 
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rx7locost wrote:
Quote:
You'll hear from a guy named Chuck shortly, now that I've said that... Heehee...


To begin with, in order to get a good set of responses, you should state your end goal and budget. Race ready? Road course or ¼ mile? What class will you compete in? Will it be a street car? What state will you register in? You have a budget of $5K , $20K or $50K? What is your age? If under 25, or have no other daily driver, you may have problems getting insurance from the Grundy’s and Hagerty’s of the world. Normal insurance companies most likely will not touch it with a 10 ft pole, especially if you go with a modern exo-body style. What prior mechanical/fab experience do you have? Do you have your own machine shop or will you be farming out the machine work. Trying to stay with off the shelf mechanicals or willing to roll your own? These all help us to focus on your car.

Chuck


Great idea rx7locost, I was actually going over and admiring your build last night. As far as the use of the car the majority of it will be on the street. Drag strip, standing mile, autocross, rallies, and track days are things I want this car to be capable of as well but as far as a serious purpose built race car this will not be one. I'm thinking the high end of this car's budget will be under 15K but am willing to be flexible to make the final product what I want it to be. I'm going back to New Mexico after school but by the time this thing is done I could be anywhere, so I don't know where it's going to be registered.

I'm 27 years old (some of you probably thought I was younger) and have been an equipment operator for most my career I've always tinkered with cars, metalwork, and welding. I've been a diesel student at Wyotech for a year, 4 months of that being a chassis fabrication class. This by no means makes me an expert on building this car but its a huge head start. I am going to attempt to do every oz of work on this car myself, that's a huge part of this for me. Final tuning might be the exception but I plan to be involved in it and learn something along the way.I do have access to a mill but no lathe. Any basic machining that I can use a mill for I'll do myself.

That out of the way I'll revisit the 600hp since that's the majority of this thread has become. Big number light car I get it, it's obscene and might never hook. I've always been intrigued by rotary engines. High revving, super simple, very few moving parts. I read an article a while back about a 20b in an RX7 daily driver running 650hp with no reliability issues, no extra maintenance, and something rotaries are not known for, torque. So that's where that number came from. In all reality the engine that's going in it is going to have around 300hp initially, I'll have plenty of time to drive it like that and have fun before spending the money to make it any faster. Suspension tuning, car familiarity, and traction will go into account before adding power. Wider tires are made for a reason. To be honest the Youtube video in one of the posts before this one is what I envisioned when I came up with this project (minus the very ugly but needed aero kit). I see these things as Veyron slayers (at the speeds that matter). I may never hit 600hp and that's fine with me but I really want to explore the capabilities of this engine, myself, and this chassis.

The engine sound as bremms says is beautiful (with revs). At idle it sounds like a chainsaw. 4 rotars sound like F1 cars at speed and like a chainsaw that needs a tune up at idle. I personally love it but I understand why people wouldn't. I want to find that perfect balance between being able to hear the soundtrack of the motor loud and clear, and not having to wear earplugs in the car.

My build is obviously outrageous to most of you. cheapracer obviously thinks so. But as I said, to me that's kind of the point. This build list was made with me knowing very little about these cars and I obviously have a lot of holes to fill and ignorance to get past. I appreciate the welcomes and the helpful input from you guys and hope to one day have something unique to share on the finished builds section, and I know a lot of it will have to do with the information I acquire here so thanks in advance.


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File comment: Our big TIG welder in the chassis fab shop. Lincoln 275
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