Datsun Roadster Forum-311s.org

I made a little progress on the supercharger install this afternoon. I worked on the adaptor plate between the supercharger and the intake manifold. I tapped all the mounting holes and bored the ports for the runners. I port matched the plate to the intake manifold and I radiused the edges for smoother flow. I used a straight edge and a caliper to align the supercharger pulley with the crank pulley. I placed the straight edge across the crank pulley and the measured from the straight edge to the inside groove of the crank pulley. I then measured from the straight edge to the inside groove of the supercharger pulley. I positioned the supercharger so that both sides of the pulley measured the same distance from the straight edge. The supercharger is now in-line and square with the crank pulley. I clamped the supercharger in position and then drilled the mounting holes. To get the ports in the right place I coated the intake manifold with Prussian Blue and then bolted the adaptor plate on. When I removed the adaptor plate there was a perfect pattern of the intake manifold. I used a hole saw and an air powered rotary tool (dremmel) to cut the ports in the adaptor plate. The supercharger is ready to mount in the car now. I still need to finish the adaptor plate for the throttle body. It will mount directly to the side of the supercharger. Two of the mounting bolts for the throttle body will also secure the adaptor plate. The other two throttle body fasteners will be studs mounted on the adaptor plate. I hope to have the rest of the supercharger install finished this week.

http://community.webshots.com/photo/267 ... 1685VeZcjf
http://community.webshots.com/photo/267 ... 1685eLXIVc
http://community.webshots.com/photo/267 ... 1685rUYvYg
http://community.webshots.com/photo/267 ... 1685ayXbcx


Later,

More progress today. I purchased another supercharger because the teflon coating came off my original one. I used some brake parts cleaner wich bubbled the teflon off the rotors like it was paint striper. I had already ported the old case to match up with the throttle body and the intake manifold adaptor so I pulled the insides out of the new supercharger and installed them in the old case. I installed some 370cc injectors. I then mounted the supercharger on the car. I was happy that there was a 1/2" gap between the recirculating valve diaphram and the starter. This was the only part I hadn't mocked up before. It looks like there might not be much room for the MAF in the fenderwell. I am contemplating cutting a hole in the cowling and placing the MAF and air filter inside the passenger footwell. I bet this will make a wicked sound. Another option would be to route it into the cowl vent and put the filter under the vent cover. I am going to use a P60 MAF from an Infinity Q45. It is 90mm. The stock MAF can almost fit inside the new one. I need to find a plug for the Q45 MAF. I suppose the dealer would have the part. Does anybody happen to know the part number?

Here are the photos from today.

http://community.webshots.com/album/267887557HfboLz/5
http://community.webshots.com/album/267887557HfboLz/6
http://community.webshots.com/album/267887557HfboLz/7

I would like to get it running tomorrow or over the holiday. I still need to figure out the belt length and route some wires. I also need to put the GM supercharger oil in it. ($18 for 8 ounces)

Later,

Andy

Looks good Andy!

Why the Q45 MAF if you're only running 370cc injectors? Are you planning on stepping up the injectors later on? The stock KA24DE MAF is well matched to the 370s. Unless you plan on going up to something like 1,000cc injectors and running LOTS of boost, the Q45 MAF is way overkill! Even the smaller Z32 MAF will support 550 Hp.

I don't know if the 370's will be big enough. We'll have to see how much power it wants to make on the dyno. I got the P60 pretty cheap. I'll never have to upgrade regardless of how much power it makes. It also has a three wire hookup which is simple compared to the Z32 unit.

370s will support 250 at the wheels. Any more than that is pushing things a little too close to the limits!

10-4 on the MAF. A good deal's a good deal. Go with it!

BTW, I like the idea of the MAF in the passenger footwell. When you need a little extra oomph, you can just reach down there with an aerosol can full of nitrous and start fogging!

you can just reach down there with an aerosol can full of nitrous and start fogging

or starting fluid.

A guy built a V-MAX motorcycle with a roots blower in the valley between the V-4 cylinders. A velocity stack stuck up through the false gas tank. The V-MAX tank is actually under the seat. The magazine editors that tested the bike said it was scary. It sounded like it would suck the watch off their wrist. Beware to insects and small flying birds. That is the effect I'm after.

I've got two sets of 275 cc injectors and one set of 370's. Maybe I'll start welding bungs onto the adaptor plate and have 12 injectors firing. If I run a cool can won't that be just as good as having water injection?

Can you just splice additional injectors into the wiring harness. Would they be wired up in series or parallel with the primary ones? Aren't there controllers out there that will convert high to low impedance on injectors?

I've got two sets of 275 cc injectors and one set of 370's. Maybe I'll start welding bungs onto the adaptor plate and have 12 injectors firing.

So, that would equate to a single 920 cc injector per cylinder. Unless you're shooting for 500+ hp, that's way overkill.

If I run a cool can won't that be just as good as having water injection?

No. Cool fuel helps prevent vaporlock in low pressure fuel systems. Return loop EFI systems run at much higher pressures and keep the fuel moving all the time so vaporlock is almost a non issue. Cooling the fuel charge will have a negligible effect on detonation which is the real reason for running water injection. With proper A/F and timing maps detonation should not be an issue. Water injection is one of those band-aid approaches that is rapidly disappearing as A/F and timing controls get better and better.

Can you just splice additional injectors into the wiring harness. Would they be wired up in series or parallel with the primary ones?

If you splice them in you would want to do it in parallel so you don't mess with the impedance. A lot of the big Hp guys will run primary and secondary injectors. Idling on big injectors is tricky and running them sequentially gets them around that. You'd need a complete stand-alone engine management system for that I suspect. I don't think any of the add-on managements systems will do secondary injectors, but I don't know that for sure.

Aren't there controllers out there that will convert high to low impedance on injectors?

Maybe, but most everyone seems to just solder in the resistors when running the low impedance (like MSD) injectors. If all your injectors are from Nissan, this shouldn't be an issue for you.

It started and ran this morning. It was quite satisfying. I was expecting the supercharger to make more noise. Maybe it will when I drive it under load. I have the 370cc injectors installed but haven't modified the computer any. It ran kind of rough but I was able to rev it up and get it cleared out. The belt and tensioner is causing me problems. I can't seem to get a belt that is the right length and still be able to tighten it with the alternator that serves as my tensioner. I may have to change the mounting of the alternator to get better range of motion on the belt. Now I will pull the motor in preparation to go to the dyno.\

I'm a happy camper.

Later,

I got the Bikirom installed and everyting seems to be running correctly. With the 4.75" unorthodox crank pulley and the stock 2.8" SC pulley it has a 1.69 to 1 ratio. Calculated out it should equal 5.72 psi boost. My gauge shows between 5 and 6 pounds of boost revving it in the driveway. The boost comes on like a light switch when I touch the gas pedal. Throttle closed = vacuum. Throttle open = 6 psi. There really isn't any in-between. I plan on putting the stock 6" crank pulley back on which will give me a 2.14 to 1 ratio wich calculates to 10.96 psi. The stock 6"crank pulley with a 2.3" overdrive SC pulley will give a 2.60 to 1 ratio and calculates to 16.34 psi. I would have to set the redline at 5384 to keep from exploding the SC but I might not really need high rpm's to get the power I need. It seems that N/A KA's tend to peak in the 5500 range anyway. I expect the dyno sheet to look identical to the N/A but just moved up the page a bit.

Later,

That's way cool, Andy! Gotta love the instant response of a supercharger. I can't wait to see some big dyno numbers. With those boost numbers, I'll bet you've got the goods to hit 300 Hp at the wheels!

Hey, you might find this useful:

http://forums2.freshalloy.com/showthread.php?t=152016

It's essentially a 35 page users guide to the Bikirom that a guy on the Fresh Alloy 240SX forum wrote. Just finished it about a week ago.

First off, an introduction...I am a long time lurker of these forums as I am looking for my very first Datsun Roadster project (most likely a 2000). Anyhow, I have never really posted before as I haven't had much to offer the forum, until this thread. I have some serious experience with supercharging as I used to work for Vortech Engineering (building blowers, R&D testing of blowers, engineering supercharger kits, etc.). I offer some tips and advice for your supercharged project and I hope you may find them useful.

Quote - 'Calculated out it should equal 5.72 psi boost. My gauge shows between 5 and 6 pounds of boost revving it in the driveway. The boost comes on like a light switch when I touch the gas pedal. Throttle closed = vacuum. Throttle open = 6 psi. There really isn't any in-between. '

Two things to remember. A) Roots style blowers are of a 'positive displacement' type. Meaning they make boost in the blower itself, not as result of intake restriction (due to engine load) like a centrifugal S/C or a turbo would. B) Your just in your driveway and there is no load on your motor yet. On the street from 3/4 to WOT boost will show some climbing and less like the 'on/off' swith effect your describing.


Qoute - 'I plan on putting the stock 6" crank pulley back on which will give me a 2.14 to 1 ratio wich calculates to 10.96 psi. The stock 6"crank pulley with a 2.3" overdrive SC pulley will give a 2.60 to 1 ratio and calculates to 16.34 psi. I would have to set the redline at 5384 to keep from exploding the SC but I might not really need high rpm's to get the power I need. It seems that N/A KA's tend to peak in the 5500 range anyway.'

Something to consider is the effciency of the Eaton M62 you have chose for this project. The M62 blower offers a great low end punch, although that model is on the 'big side' for you KA24, especially if the motor is fairly stock. Any reason a M45 wasn't used? Their efficientcy (either model) doesn't do well when you creep in to the higher boost ranges. Looking on Eaton's website, at the few testing spec's they offer, thermal dynaically aboost pressure of 16PSI will : A) Cost a lot of crank HP to spin the blower and B) Be pumping more heat (I'm betting 400F+) than useable boost. Even the best roots blowers only hit a peak efficency of 65%. They don't call roots blowers 'hair dryers' for nothing! All kidding aside, 5-10PSI is a lot of bolt power to play with. Especilly in roadster.


Qoute - 'I expect the dyno sheet to look identical to the N/A but just moved up the page a bit. '

It probably will with two exceptions: A) The torque peak will come on earlier and harder. B) Expect the peak HP RPM to increase 500 to 1000 RPM on average due to increased breathing.

You had mentioned in an earlier post about having belt tensioning issues by using a the alternator as the fixed tension device. If that doesn't work, consider running a spring loaded belt tensioner (from full size truck car, as long as it's a 6 rib unit) and mount it on the 'slack side' of the blower . Another thing to consider is that this blower runs a 6rib serpentine blelt. Belt slippage for 8PSI and above is very common limitation of 6rib systems. But they act as a rev limiter for the blower should an over rev occur. Cog drive is a whole other story that requires some thougth and safety features to work well.

Lastly, I'm curious about the fuel managment , ignigtion management, and exhuast? Any thought on after cooling?

I hope I have shed some light and helped in any small way with your blown KA24 build. I'm here to help if needed. I'm looking forward to seeing the dyno sheets and numbers.

And yes, I plan on building blown roadster and may even make a kit available if there is enough intrest in it.

Roots style blowers are of a 'positive displacement' type. Meaning they make boost in the blower itself, not as result of intake restriction (due to engine load) like a centrifugal S/C or a turbo would

I think you got that backwards. The centrifugal blowers (Vortech) produce their pressure inside the housing as a result of the centrifugal acceleration of the air. The roots style positive displacement blowers do not compress any air inside the blower. They just move the air from one side of the blower to the other. What makes boost is the fact that the blower will move more liters of air per revolution than the engine displaces. Assuming a 2 to 1 pulley ratio this blower will pump 2 liters per engine revolution. Because it is a 4 stroke motor it takes two engine revolutions for all four cylinders to fire. In four engine revolutions the engine consumes 2.4 liters of air however the blower is forcing 4 liters of air into the motor. This causes pressure to build. Note that this ratio is independant of rpm. The same 4 to 2.4 ratio applies at 500 rpm or 7000 rpm. In thoery the boost will remain constant throughout the rpm range. I know that my Supercharged MR2 had 10 psi from idle to redline.

On the street from 3/4 to WOT boost will show some climbing and less like the 'on/off' swith effect your describing.

This motor will never go on the street. It is a race only motor. It is possible to get some boost climbing. The nature of autocross is that I will only have full throttle for 1-3 seconds at any time.

Any reason a M45 wasn't used?

1. At .75 liters the M45 could only make 3.5 pounds of boost by my calculations.
2. The M62 Xterra units are dirt cheap ($100) on Ebay.

Be pumping more heat (I'm betting 400F+)

P1T1=P2T2
Heat is caused by compression of gas. Any type of compressor will cause the same amount of temprature rise. The extra heat is caused when the blower is run outside of it's efficiency range. The gas does not exit the blower and the rotors just turn inside the stagnant air. The blower doesn't make more pressure it just makes more heat. Keep it in it's range and it will be comprable to a turbo or other type of blower. There are lots of misconceptions about roots blowers. Here is a link to a writeup from Magnuson who is the Eaton authorized rebuilder. They sell all kinds of blowers and have a comparison of the different kinds including Vortech. http://www.hiperformancestore.com/Magnu ... argers.htm

They don't call roots blowers 'hair dryers' for nothing!

You got that partially right. Actually, they don't call roots bolwers hair dryers at all. They call turbos hair dryers because of the sound they make and their resemblance (centrifugal) to the turbo.

Lastly, I'm curious about the fuel managment , ignigtion management, and exhuast? Any thought on after cooling?

I am using a Bikirom megaboard. It soliders into the stock ECU and has a USB port. It renders the stock ECU completely programmable. I can alter any parameter including the ignition curve, injector size, MAF size, fuel maps, rev limits, etc... There are aux inputs for a host of other sensors including wideband o2 sensor, EGT, MAP, etc... It has outputs for a relay board. The relay board can control things like radiator fan, 2 stage rev limiter (drag racing), boost controller, water injection, etc...

I plan on using water injection if needed. I think I can get a 100 degree drop in temperatures which is comparable to an intercooler. I may use race gas too.

The exhaust ends at the end of the header. Right now I have a supertrapp with 18 discs in it on the end of a tube header. In the future I may run a pipe to the back of the car with some sort of muffler.


I'm running with a 4 rib belt at the moment. If it slips too much I will start looking for a solution. I'm sure I can find an OEM 6 rib unit that will work with the KA24DE or I might have a pulley custom made.

Later,

I drove it out of the driveway and onto the trailer. The short drive down the street and onto the trailer was quite exciting. It fried the tires like a top fuel car. The open diff left two black streaks. I suspect one was reverse rotation. I had to route the intake through the firewall and into the passenger floorboard. I probably could have kept it all in the engine compartment but this configuration fit with the pipe bends that I already had. The thing is kind of scary. The sound from the supercharger screams " I'll suck your watch off your wrist and chew it up." The sound was thrilling and terrifying at the same time. Beware to low flying birds and insects.

I am having problems with the Bikirom. The ECU isn't switching to daughterboard mode. I moved the jumper from CJ1 to CJ2 which is supposed to enable the use af a daughterboard. It is still running off the stock map in the ECU and not the daughterboard. I think one or more of the 84 solider joints that were performed could be bad. I'm going to take it to a professional on Wednesday.

I'll be moving the motor back in the engine compartment another 3 to 4 inches. I will probably have to notch the X-member a little bit for the tranny. I'm pretty sure that the RX7 pinion is longer and would require a shorter driveshaft. I have a 240Z driveshaft that is about 6 inches shorter than the 1600 roadster unit. I think that the motor placement will be determined by the length of the driveshaft. I just don't want to spend $200 to have a custom driveshaft made. I can deal with changing the u-joints to match the RX7 yoke and then moving the motor back. I thought about moving the motor back until the head was in the doghouse. The supercharger sticks out too much and will only allow about 4 inches before it hits the firewall. This is fine with me because I didn't really want to screw with redesigning the throttle linkage or the brake lines.

When I move the motor back I should gain the added clearance for the stock crank pulley and the power steering pump/water pump belt will clear the steering u-joint.

Later,