LocostUSA.com

I've highjacked the v-8 transaxle thread enough that I thought I should start a new thread.

I've been dreaming about building a lightweight midi can-am style car with a full cage, windshield and a v-8 for the street. I have even considered "borrowing" parts from my current car , at least during the design stage. I mean I could build a whole midi using all the components I have(engine tranny diff spindles rack wheels tires etc) and just adding a transfer case and some odd length axles (and a bunch of tubing , sheet and fiberglass) end up with a v-8 midi.
My only problem is trying to figure out a "realistic" weight goal. I figure the final result would end up at best no lighter than my current car if I used the same components over, and at worst more than my current car due to the transfer case.
So I am thinking the only way to make it lighter is to start with lighter components and make the car physically smaller. Lightweight 13-15" tires and wheels at least for the fronts to reduce weight and improve aero , brakes designed to stop a miata sized car, as much 1" and 3/4" tubing as I can use. Corvette transaxle would be ideal for robustness and price but would stretch the car out to at least a 114" WB and that might hurt my weight goals. So either a Porsche/Audi box or a transverse f40 gm box(the ones their using in the LS fieros) would be needed to keep the overall dimensions compact.
I realize that it's a total guess but do you think it would be possible to get the weight down to 1700 lbs using locost type components?

Phil

My vote is for the 4.2 Audi V8. .. alloy block, 8k+ rpm and 570 hp with a supercharger.

Phil
What engines are you considering? I believe the iron block for LS engine adds about 80 pounds versus the aluminum. That, combined with the weight of all the other components I listed in the other thread has to be about 300 pounds. Take that from my 2441, and you are around 2100.

The Corvette brakes are heavy with 13" diameter rotors. I think your idea about smaller brakes will help a fair amount. When you consider all the other pieces that make up a corner, it gets heavy. The Corvette halfshafts weigh 20+ pounds each.

I think you could do it for 2000-2200 pounds.

Ken

Phil glad you start a thread for this. It would be good to have a "locost" midi frame. I'm actually bending tube right now in SketchUp for this.

I'm hoping for under 1500 lbs., but maybe a I need a dose of reality. We can start with a weight budget and I can add up the tubing weights for my frame soon. My approach is to take the passenger compartment of the frame I'm working on ( I take some comfort from the roll cage size tubing, but it could be reduced ) then just take the front suspension bulkheads and graft them right onto the passenger compartment, removing one bay from the car. One needs to decide where you want the front wheels, for CG and safety tradeoffs... Then extend the rear roll bar braces to where the rear coilovers attach.

Perhaps we can get Gonzo to weigh his V8 before he puts it in his car? Wheels and tires are a big weight. I think you can still put a Seven on 13" wheels, but this might be harder in the HP range you probably want. I noticed the other day the front wheel and tire on my FF only weighs about 20 lbs.

I think the stronger transaxles you would be looking at will weigh in around 120-130 lbs. If you do not need to do standing starts, your drive train can weigh less.

Looking at my SketchUp model the front wheels can move back 30" without much effort. So getting your build into something like a 94" - 96" wheelbase looks pretty doable. Again maybe overlooking some things. Looking at models in SketchUp, you can come up with how much your frame weighs per inch at various places in the car. From a quick tube count I would say mine run 10 - 15 lbs. per foot thru the cockpit. Depends on tube sizes etc.

Want to start a weight table? You could edit it into your first post in this thread. Here's a very small start, Miata and Mustang II (Wilwood) front spindles both weigh 9 lbs. each.

I was considering an alloy LS engine. I have also thought about using an A8 audi powertrain but don't know about their weight and how easy they are to modify. The LS engines have alot of support for reprograming and modification easily available and reasonably priced.

Phil

Sounds like you and me are on the same page here. My idea is a car that can pull into the track and race with no more than a tire change.
It may be the only "lemans" prototype with a trailer hitch.

Hi Phil-
As Marcus suggested, I'll be happy to weigh my engine when it gets assembled, but it's a Ford 302 and not all that relevant to your build. (Somebody else's build, maybe?)

Also, in another thread in here, we had a brief discussion of motor plates as a way to mount an engine and stiffen a chassis. What's the possibility of using similar plates on both ends of the LS block to BE the chassis instead of stiffening one? Run small (0.5") tubing between them to hang body panels on and attach a subframe to the rear plate and the transaxle to mount suspension components to, much like in old Formula cars. Just thinkin' out loud... Don't know if any of that is actually do-able...

The mid engine V8 is a cool idea though, I thoroughly enjoyed watching your first V8 build, so I'm looking forward to seeing where this one goes!

Good luck!

JD Kemp

Further thoughts:
Mustang II/Pinto spindles are a good way to go, light and relatively strong. Same is true of the steering rack.

Pook seems to like Solstice front spindles for his builds, so they must be pretty good as well.

OK


my contribution to the weight table

current wheel and tire weights total = 226lbs

fronts 275/40/17 Vredstein Ultrac Sessanta 26lbs
17x9 cobra rim est 26lbs

rears 315/35/17 Vredstein Ultrac Sessanta 31lbs
17 x 10.5 cobra rim est 30lbs

proposed wheel and tire combo = 163(63 lb saving)

fronts 225/45/15 toyo r888 20lbs
6ul 15 x 8 12.4 lbs

rears 315/35/17 toyo r888 30lbs
6ulr 17 x 11 19lbs

current trans axle combo = 210lbs

T56 with bellhousing only 125lbs
8.8 from explorer est 75lbs
alum driveshaft and 2 loops est10lbs

proposed = 125lbs (85 lb saving)

audi est 125 lbs


exhaust

current 2 mufflers 23LBS each = 46lbs

proposed single dual inlet muffler = 23lbs(23 lb savings)


So changing those components only should bring my weight down from 2000lbs to 1829lbs.
The proposed frame is 12" shorter , made primarily from 1" material so should save about 50lbs. So I am down to
1779lbs.

current front spindles mustang II at 9lbs x 2 + wilwood 11" brakes (40 lbs)= 58lbs
anyone know what the miata setup weighs?

phil

For those of you who missed the first part of this , its in the v-8 capable transaxles section.
I leaked one of the dozens of very basic midi plans I have drawn and horizonjob convinced me I should share it.
It's here.
http://sketchup.google.com/3dwarehouse/ ... revstart=0
Had some fun with jokes about it falling over and it being light because its only 1/2 a car.





My take on the weight penalty per foot for my proposed design.

I assume the cockpit and front end stays the same regardless of engine choice. Remember I am just "thinking out loud" here. I was actually thinking of just building the front end and cockpit first . Should be the same regarless of powertrain choosen.

So the only difference in weight would be from the various powertrain weights and the chassis length required to accomadate them.

re the chassis weight in rear section
4pc 1"sq x .063 x12" tubing main frame rails=3lbs/ft
3pc 3/4" x 063 x 14"(due to angle) diagonals tubing=2.2lbs/ft
3pc 1.5" x .095 x 14" tubing roll cage and brace=5lbs/ft
1pc .050 x 12" x 14ft alum sheeting(enough to cover top ,bottom and sides of 60"x24" body)=10lbs/ft
total = 30lb/ft
so adding 18" to the car to allow use of c5 diff adds about 45lbs to chassis and body plus whatever the weight difference between an audi box and a c5 box is (estimated at + 75 lbs) so about 120lbs'

Phil

The Chevette/Fiero stuff comes in at 26# per side so there's a smallish setup saving 6# in unsprung weight.
The Audi 4.2 weighs in at 467# with the dual mass flywheel/clutch assembly used in the "high rev" version according to this Audi publication. .. http://www.s4-mtm.com/images/RS4V8-StudyGuide.pdf
I'm assuming that's with the accessories included since they run off of the cam chain which would mean you could reduce a little by taking off the A/C compressor.
Interestingly Audi uses a master/slave setup on the high rev version and paired 2 ecms as if it were two 4pots with a common crank. .. MAF, IAT, COP, VVT, crank angle sensor, multiple cam sensors, blahblahblah.
Sounds like it's apparently a fairly common Bosch unit with several vendors listing reflashes.

Something interesting in general, the RS4 has a dual outlet muffler with a vacuum driven door on one of the outlets. ..
City and Highway settings anyone?

So, if "Pmatolcsy" builds a Locost powered by an Audi engine like a Donkervoort would it be a "Donk-atolcsy"?

I wonder where all the weight is? If we keep up the table we can find it. Egoman says his oval track cars were down to 1200. Headlights, windshield and wipers etc. are going to cost...

Phil I hope you don't mind these picture's, I'm not sure if you want this to be just "Phil's can-am thread" or not. I was already doing this today when you thread popped up. What this is is some quick cut and pasting in my shop to get ready for a midi or AWD rear engine Subaru. Like Phil was saying from the driver forward these cars are basically the same. Tomorrow I will start adding up tube weights and see where we are up to the roll bar.

I've the Blue Midi in the second photo. I see it's a whole car now, but I'd swear the passenger is trying to steer the car too. Perhaps they are scared... I see in Phil's car the front wheels are further in front of the passengers. The way I am drawing this it is mostly an issue of which way the wishbones are facing. I am trying to make the front on this pretty sturdy. We'll see if that is making it heavy.

He is. I had to take his steering wheel away so everyone didn't point out I had 2 drivers. Besides If I reach my weight and performance goals , I figure all my passengers will be trying to drive anyways.

I'm at work now , but its quite easy to "hide" the body panels and see the basic chassis. The chassis needs to taper quite abruptly at the front to allow reasonable width in the passenger compartment, combined with reasonable length A-arms. I believe if you look at the rulebooks (SCCA?) ,the drivers feet must not extend forward of the front axle centerline. I have the front axle centerline approx 6" forward of the front "firewall". Then 60" outside to outside length for the passenger compartment, thats the size that worked in my locost. Then 30" to the rear axle centerline(my estimate for an ls1/audi combo). I realize that at those cramped dimensions , the harmonic damper and accessories may impinge into area I have drawn as the fuel tank. BB69 has given this dimension for his engine transaxle as "The distance to the axle centerline is about 47" for the c5 trans ls1 combo so this would increase the wheelbase from 96" to 113". Perhaps Pook could give us a dimension from the front of the harmonic dampner to the axle centerline for his various setups ?

Phil

That's am interesting difference in our models. I just go straight from the passenger compartment to the narrower part of frame for the front suspension box. I think it comes out quite strong and there is a little more foot room.



How tall are you? That's a few inches longer then my models, but I don't have a real car, so I could use some real input here. You might also want to try the wooden person I am using. You can move all the parts of the wooden person, but it takes some time. You could also scale it to match your own personal size. I did flesh out the front suspension and frame on my model and will put another pic in if you like. I also have somewhat better models now of the V8 and Subaru that I made by including a picture for reference. I've asked a couple of people for more transaxle pictures so we should soon have something that we can put in the car and really look at.

The wheelbase on your model is roughly 92", but I think there's a few inches missing on the front of that V8. I have a photo reference for that V8 model, so I will find it and include that too tomorrow. It's from the Chevy crate catalog.