Birkin42

Where can we buy the ones you used on the SR27?

Stock, my Birkin frame stripped down to the bare frame with no aluminum panels on it was about 95 lbs. This does not include the roll bar (if you want to call it that) either. I'm adding about 10 lbs to it to accommodate mounting the S2000 drivetrain as well as provide mounts for the IRS differential.

I found these at SEMA last year. http://www.xsighting.com/ I have no experience with them but they look like a quality unit. They offer 5-3/4" and 7" round lights as well as a bunch of others. Not cheap though at $785 for a pair of 5-3/4" and $890 for a pair of 7". Ouch! I'm guessing there are others on the market. I think any real HID light isn't going to be cheap though.

I would think that the air intake on Tim's car is intended for a formula or sports race car. I would also guess that it is made to comply with a rule for a specified intake restrictor size and likely doesn't have anything more then a wire screen as a filter. You may have some luck finding a source, but I would recommend you use a filter if you car is intended as a street car. Tim's car is race only and can get away without a filter. For the traditional filter route, a good option is ITG like Al recommended. You can get similar filters from K&N, Pipercross and likely others if you look around on the web.

The drive shaft in my car will be about 18" long and won't be too heavy. I believe you have a Deman. I helped Dan sort out his drive shaft issues a few years ago when I was considering buying one of his cars. I agree that BEC have unique drive shaft requirements, but this does not make them light weight. I'm not sure if you have the 2 pc version with the hanger bearing or the 1 pc long shaft. In either case, the total length of the shaft is about 4 1/2 ft I believe. Either version but particularly the 2 pc version is going to be significantly heavier then what I will end up with. The torque that each need to transfer isn't likely too much different either. The S2000 has a bit more torque, probably has a lower first gear, but uses a 4.11 rear end. Your Busa doesn't produce as much torque but has a significant primary reduction in the engine which slows down the speed of the drive shaft and increases the torque load on it. This is reflected in the 3.08 rear end. I think in the end it will be close to a wash. I am not trying to pick a fight or anything, just trying to add my opinion. Anyway, the point of my previous post was to agree that a BEC will be significantly lighter even with a few unique bits that a more conventional drivetrain wouldn't require.

I'm guessing a small amount of the weight savings will be lost to a heavier more complex drive shaft, and the mechanics to provide reverse, if you have it. Needless to say, it is way lighter then any auto based drivetrain.

Measured the weight of my trany last night and got the same 96 lbs. That makes the engine about 280 lbs, maybe not the lightest out there, but not bad considering out of the box hp, stock Honda reliability, and relatively cheap to buy used. Those Toyota motors aren't particularly light.

You likely can buy basically the same seat (in fibre glass) from Deman Motorsports. Might be cheaper then getting it in from the UK.

Interesting thread. I will have to go and weigh my transmission separately so I can see what the break down is. The hard thing to know is what parts are all included when someone states engine weights, or are they troughing on light weight parts like altenators, clutches, etc. Looks like the S2000 will be very similar weight to the standard Zetec with T9. Nice to know. Looks like the newer Duratec is a bit lighter still. Those K series seem to be really light. I guess the ultimate in weight savings is a BEC. Maybe some day.

How light is a K series complete with transmission? The engine was never available in Canada as far as I know so it definitely wouldn't make the most convenient donor for me. Now a bike engine based V8, now we're talking.

I weighed my S2000 engine & transmission last night. It came in at 375 lbs. This weight includes the complete engine/trany with clutch, starter, alternator, engine & transmission mounts. Pretty much everything but the wiring and AC compressor as well as no exhaust parts. I was curious how this compares to others. In particular, I'd like to know how this compares to a Zetec with T9 trany as would normally be put in a Birkin.

I think there are 2 ways to approach this. You could find out the engines primary gear reduction (from the engine to the clutch and transmission) and the ratio in top gear. Knowing this as well as determine what the revolutions per mile that your chosen tire and wheel combo will have, you can determine the preferred gear ratio based on max rpm at max anticipated speed or preferred rpm when traveling at say 60 mph. If all this math is daunting, you can let us know what engine you are using, what tire size you plan to use and what you want to traget for speed vs rpm and I'm sure someone could to the math and get you going in the right direction. Another approach to get you in the ball park, consider that likely your rear tire diameter isn't going to be too far off the bikes tire diameter that the engine came from. Most bikes run 17" wheels and will have a taller profile tire then what you will likely run on your 7. Depending on wheels and tire combo you want to run, you can likely figure out the ratio of diameters but I'd guess that yours will be about 80% the size of the bikes rear tire. You can then look at what final drive ratio the motorcycle used (the chain and sprockets driving the rear wheel). The final variable again is the relationship of rpm vs speed you want compared to the bike. I would guess that you would be looking at about 25% higher engine speed for a given road speed. Conveniently, the 80% and 25% cancel each other out and you end up needing a final drive ratio similar to what the bikes final drive was. Most bikes run close to 3:1 reduction so like BusaLoco commented, 3.08 is likely very close to what you want. I know this is what Deman Motorsport put in their BEC cars. If you are running an engine smaller then the typical litre class + sport bike engines, you may want more reduction like your 3.9:1 to get good performance. The other combination where your 3.9:1 ratio might be OK is if you are planning to run larger then normal tires for a 7. This would be an awfully big wheel and tire package though. Something you might see at SEMA but not typical for a performance car. Do you have the engine as well as the tires and wheels picked?

Chuck, Just to start off with, I have purchased all the dry sump parts for my car, but I am now where near having it running or on the road yet, so what I am doing is not proven. I think I've done my homework so I think it should work out, but time will tell. I am using a Peterson 3 stage pump, 1 pressure & 2 scavenge. Both scavenge sections are for the oil pan. I have no plans to directly scanenge the head. My pump has std 7/8" sections for all 3 stages. Peterson pumps gerotor type so sizing of sections may not be comparable to the make and model of pump you are using. For the pressure section: Ultimately what you need to do is match (slightly exceed) the pressue & flow demands of the engine. The std S2000 internal oil pump is rated at 58.4 litres/min at 6000 rpm and the relieve is set at 85 psi. At the 9000 rpm red line, the flow works out to 87.6 litres/min or 23.1 usgpm. Obviously you want enought oil flow to make sure you don't loose oil pressure. Assuming Honda sized their pump correctly, matching the flow should be fine. Providing significantly more flow is just waisting hp and creating extra heat in the oil as it is relieved over the bypass. The flow of my pumps pressure section is 16.3 usgpm at 3000 rpm and has a 5000 rpm limit. I ended up with a drive ratio of 2:1 so my max pump speed will be 4500 rpm and flow will be 24.5 usgpm. All of this sizing was discussed and approved by a tech from Peterson. They said this should be fine for a relatively stock motor with the stock red line. I am using a single AN-12 line to connect the outlet of the pump to the engine which matches what you are doing. The pumps internal relief is internally piped to the scavenge return to tank port. Your AN-10 should be fine as long as the pump is not grossly oversized. The standard size fitting on my pump and tank for the line feeding the pressure pump was also an AN-12. From my industrial hydraulics experience I felt this was too small and thought going up to an AN-16 line will only help insure the pump doesn't cavitate. For the scavenge section: I guess this all comes down to how much vacuum you want to draw. The theory is that more vacuum = more hp. I wasn't too concerned with this and was more concerned with very limited space for the pump, lines, etc so I only went for 2 scavenge sections. Peterson recommended that as long as I had 2 scavenge sections that were the same size as the pressure section, I should be fine. This of course is totally dependant on getting the scavenge pickups in the pan in the right spot that they are sucking oil and not just air. For line size, I am going with 2 AN-12 hoses to the pan, 1 for each section. For the return to tank I am running a single AN-16 line. My pump has the option of internally manifolding the outlets together, so I am doing this to keep the number of lines down. I would recommend using 1 AN-12 hose per section for both the inlet and outlet. You can manifold the return to tank lines and run 1 line. This line should be at least one size up from the pressure out line size. You should consider running scavenge filters in the lines from the pan to the pump just to protect the pump. The Tank: You tank size should be OK. I doubt you will be able to run 7.5 quarts in it. I'm guessing that is its total internal volume. You can only partially fill these tanks as you have to keep the oil away from the inlet and breather. I don't know how much you'd actually be able to run in your tank but likely something like 2/3 full. My tank is slightly larger, being 7" diameter x 16 1/2" tall. Again in sizing a tank to fit in a 7, size is always going to be a limitation unless you are going to totally sacrifice the passenger compartment or something. Large is better, but I figure anything that is somewhat larger then the stock oil pan capacity should be fine. The tank I am using has a built in breather tank and filter so this made dealing with this easy. In your case, I would comment that your tank vent size is very small. To try and keep the oil in

I just emailed them to you. If you don't recieve them or need me to use your ftp site, let me know.

My 7" drag tank has an 8 bolt flange. If clocking the fittings are a concern, why don't you specify their locations when you order. As long as you keep the inlets (near the top) tangential (to promote swirl and keep the oil away form the central beather pipe) I think you can pretty much get them to put the fittings wherever you want. I did that with mine for no extra charge. I even had them upsize the outlet to the pump to the next size up fitting for no extra charge. I have a CAD model of the 7" drag tank that I bought. I created this to help explain to Peterson exactly what I wanted. It is relatively accurate as I adjusted the sizes to actual once I recieved the tank. The model is in SolidWorks but I can also send it as a 2D AutoCAD dwg or pdf of the drawing. Thought it may be of interest or could help.

Didn't know Peterson had an 8" tank. My catalog only shows a 6, 7 & 9" diameter tanks but my catalog is not the latest and greatest. I think their diameter spec's are for the OD of the body of the tank and not the max OD. Maybe what you are calling an 8" tank is the same as my 7" tank? Peterson seems to use 2 styles for a joint to split the tank. My 7" tank uses a bolt together joint. It looks like Mocal uses some kind of a band clamp that I'm guessing pinch the O-ring. The flanges are fully CNC machined and look like they do a good job of sealing their tanks. I believe they are slowly coverting all their new tanks to this style. Wait unitl you look inside. They definitely put a lot of technology into controlling the oil flow in the tank. The cost for my tank including breather was about the same $300 with the mounting brackets being extra. I thought this was a pretty good value especially for a made to order tank. Jack

I can't help you with dimension on the Mocal tank. I am dry sumping my S2000 engine and went with a custom Peterson tank. By custom I mean they started with one of their standard tanks and allowed me to dictate the size and location of all the fittings as well as the location of the add on extrenal vent/overflow tank and breather. To boot, the cost of the complete tank and breather was cheaper then the Mocal tank you are looking at. They didn't charge anything extra for the custom since they make all tanks to order anyway. It took a few weeks to get, but the finished part looks great. They do really nice work. I went with their 7" drag tank which seemed to fit perfect in front of my shorted passenger foot well. They offer a large range of tanks so you should be able to find one that works for you. Their catalog isn't too great for dimensions, but I believe you can get most of this off their web site or you can contact them direct.

Air travels due to a relative pressure difference so who says the force to fill the cylinder is from the vacuum or from the atmopheric pressure. I went with the vacuum since it is the motion of the piston creating the pressure difference.

96% first try. I know I got one electrical question wrong. Not sure which other one. I answered suction from the piston going down on the intake stroke.

I have a few concerns with your design, if I am understanding it correctly. My concerns are with the friction in the joints, stiction in the cylinder, and most importantly, the rising rate geometry of the scissors. As you compress the scissor, the tension force on the cylinder will increase at an every increasing rate. So for example, if the scissor is compressed to say 5" and you have 500 lbs on it, you may have a pressure reading of 1000 psi. If the scissor was compressed further (less oil in the cylinder) to say 4" and you have the same 500 lb load on it, the pressure may now read 1500 psi. I think it will be hard to calculate the actual weight taking into account the force amplification/reduction in the scissor. Even if you only want to compare one corner to another and don't care about actual weight, you would need to verify that the scissor geometry is near identical at the corners you are comparing. Unfortunately pivoting links that this issue. Some times it is a benefit, some times not. Am I understanding your mechanism correctly?

He spent a lot of time modeling and it looks pretty cool. I know in SolidWorks you can even take it one step further and add lighting etc to the point where it practially looks real. I would have like to have seem a lot more triangulation of the frame in the front though, from a design persective.

I can provide any dimensions you need from a Birkin S3 live axle chassis, but don't have info on the Caterham chassis. There are a lot of similarities but the tunnel rear bulk head are definitely different. Out of curiousity are you modeling it up for fun, to recreate your own copy, or to use this as a starting point and modify to suit a different drivetrain and/or suspension?

You got that correct. The red and silver A-H 100 has a Jag 3.8 6 in it. The yellow 100 has a supercharged Jag V12 in it! Both of them are really nice jobs but I can't see the V12 ever hooking up with the tires and wheels on it. The red and silver car is for sale. He's asking $74k CDN. Did you notice the TR6 with the Vette engine in it?

I agree and don't plan to put any weather gear on my car, though the boss my decide otherwise once I get the car on the road. Thought it was a nice simple solution, but then again moveable windows on a 7 seems like an extravagance.

When it first drove in, I thought it may have been a dook, but I believe it is a Superformance S1, or am I wrong? Nicely built car. I like the slide up side windows. The pivot from the back and slide up and down from the front. They tuck nicely into the door pockets.