Datsun Roadster Forum-311s.org

I just wanted to update on my progress. The MP62 supercharger is installed and working well. I have the car all apart so I haven't had a chance to drive it around. It was making about 6 psi of boost with the underdrive pulley on the crank and I estimate in the 10-13 psi range with the stock pulley.

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I have been waiting on my Bikirom fuel management computer to be repaired. The Bikirom guy contacted me today and said it had not been working correctly because of a bad solder during manufacturing. He repaired it and it has been shipped back to me. Soon I will put the motor on the dyno and do some tuning.

http://filebox.vt.edu/users/bkline/docs/BikiROM.pdf

I replaced the stock MAF with a unit from a Q45. It is huge and can support much more power than I will be making with the supercharger. I also modded a set of factory fuel injectors. The stock ones flow at 275cc per minute. I have a set of 370cc injectors but was concerned that they would be too small. I found some postings where Subaru guys were modding the WRX injectors which are identical to the KA24DE injectors. After the modification on my stock injectors I measured 680cc/min on my homemade flow tester. I just basically ground the end cap off. I have details if anyone is interested.

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Injector before mod


Injector after mod




I got the huge wheels and tires mocked up on the frame while I'm waiting for my axle to be narrowed.


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I'll let you know how the dyno tuning turns out. Any guesses how much power the motor will make on 13 psi with custom tuning?

I'm loving this build up! Those tires look awesome!

OK, let's see here. 13 Psi, no intercooler, (please tell me you have something to monitor for detonation), I'm going to say 250 RWHP, uncorrected, at 5,000 RPM. I'm also going to say you'll likely end up dialing it back to 7 to 8 Psi for "normal" use and end up with 210 - 220 RWHP at 5,000 RPM.

The Bikirom has over 20 triggers and several outputs. I think I can hook a trigger to the knock sensor and have it switch to an alternate ignition map. The Bikirom allows for custom ignition maps so I can mess with the timing if I start to get detonation. I am also considering methanol/water injection if necessary. I would rather not because it would be a hassle to monitor the level in the reservoir . I just want to show up and race and not have to refill gas and methanol all the time.

I'm hoping for 350 at the crank but am realistically expecting 250-300. There isn't much way to dial back the boost except by changing the diameter of the pulley.

Andy,

What will the width of the car be at the front and rear wheels? What did you do with the Libres/slicks? Looking good!

Wait, are you doing a chassis dyno or an engine dyno? I assumed chassis. OK, 250 at the wheels, 290 at the crank. There, that covers both bases. That's my guess and I'm stickin' with it!

Yeah, I figured you'd end up swapping the pulley out to run less boost. I suspect 13 pounds with no intercooler is not going to make that engine very happy for very long.

It is an engine brake dyno. I think these are more useful for tuning purposes because you can run at part throttle.

I sold the libres and slicks to a 510 racer. The new wheels are very light 10 pound wide five wheels. 15x10 in the front and 15x14 in the rear. I am going to have to add some spacers to get the clearances right. The rear track will be around 60 inches and the front around 65 inches. Currently the wheels rub on the brake calipers and a-arms. I will probably have to adjust the turn radius to keep the tire from hitting the swaybar at full lock.

"This one goes to 11."

I swapped to the stock crank pulley and replaced a leaky front main seal. The boost gauge says 11 psi while revving in the driveway. I suspect a little more boost will creep up while driving.

The new crank pulley is large enough that it hits the cross member. I did have a big dent hammered in there to clear the underdrive pulley but there is no way now. I plan to move the motor back until the front pulley is behind the crossmember. The motor should rest nicely in the cutout in the firewall.

I got the bikirom working and now need to tune the motor with it. It is pretty cool. It displays all the data on the laptop screen including MPH, rpms, coolant temp, ignition advance, tps, maf, etc... It also datalogs the wideband O2 reading versus the fuel map. I can change the fuel map in each of the 256 bixes based on the A/F ratio.

Later,

Ok here is the video of the cool sound it makes and some photos of the steel plate tensioner bracket.

http://community.webshots.com/video/3066030610065431685

Click on photo for full sized image

Oh my..Got goosebumps just hearing that monster scream..

I'm running a na KA24de in my 66 and there is enough power to give quite a thrill on the street . I can't even imagine the rush it must be like to drive your set-up on the track.

It sounds good!!

poor me....no sound to video....

You probably need to install the latest flash player.

nomadtrash wrote:I also modded a set of factory fuel injectors. The stock ones flow at 275cc per minute. I have a set of 370cc injectors but was concerned that they would be too small. I found some postings where Subaru guys were modding the WRX injectors which are identical to the KA24DE injectors. After the modification on my stock injectors I measured 680cc/min on my homemade flow tester. I just basically ground the end cap off. I have details if anyone is interested.

I'm interested.
Tell me more.

http://www.ka-t.org/forums/viewtopic.ph ... sc&start=0

I got 680cc out of my stock 275cc injectors. One was only 660cc but I have a bunch of spares and modded another so that I had a full set at 680. It isn't as precise as having them professionally cleaned and flowed at witchhunter but seems to work well. I feel that this mod is completely safe because none of the working parts of the injector are messed with. Only the little diffuser on the tip which is basically a restrictor is removed.

I was able to get the car to idel and run quite well on the modded 680cc injectors by using my bikirom.