Finally got the time to go dyno my car

goldrocket · Postby **goldrocket** » Fri Jun 13, 2008 9:14

Well I would first like to thank Frank Rekenberg at SR-Tuning for helping me get the car tuned and solving some of this car's mysteries. I started the morning of Wednesday June 11th. We got the car strapped down, fired up the fans and had to do some tweaking in the software for the data acquisition system to read the RPM due to the MSD ignition. This is no suprise as a lot of factory Tachometers have issues with multi-strike ignitions. This took all of a couple of minutes and we installed the exhaust probe for the lambda sensor to measure Air Fuel Ratio. Once we had it all situated we did a warm up run to get the car to operating temp. After all, this isn't about spiking the hp and torque numbers, it's about finding out what the accurate numbers are. I have to start by reminding everyone that my car, unfortunately, is not fuel injected. this was going to be a process. the first actual measured run yielded 149Hp and 103 Ft-lbs of torque. A LOT less than I expected. As I did expect. the horsepower comes on very hard above 5000 RPM. When I sent my engine to be ported and rebuilt, the builder claimed that with my ignition and induction combo that I should expect 250-260 hp. That should yield approximately 175HP on a chassis dyno. So they missed the mark. At least I have been happy with the cars performance. Anyway, when we looked at the AFR charts it was horrifying! It went all over the place. And it has a bad lean spike when I go to full throttle. I replaced the main jets and added 5 degrees of timing. It got worse. I changed the air corrector jets in the emulsion tubes, It got a lot worse, down to 139HP. So we decided to sit down and analyze what was going on. Obviously there was an issue with the air corrector jets, but I used what was in the shop and went way too small. I planned on going to the auto parts store and buing some jets for Friday morning and moving forward. I left Wednesday night with my poor car gasping for air around 6k and begging for gas on the bottom. Frank asked me to bring him my weber manual so he could see a diagram of the carb circuits, I have one so I did. Nobody stocks the type of jets I needed, so I had to improvise. I had 270(2.7mm) jets in the emulsion tubes before making changes, they were way too big. The biggest frank ahd were 200(2mm). So I did what any resourceful guy would do. Bought some 2.4mm drill bits and made the 200's into 240's. the car was already strapped down to the dyno before I pulled the carb tops and removed the jets for drilling, so I put it back together and we fired her up. On the warm up run it was obvious we were going on the right direction. Again, we were more concerned with getting the AFR to be in the right range and linear through the RPM range. drilling the air corrector jets was on the money, but Frank felt we needed to go with smaller main jets. He was right. I went from 170's in the primary main to 160's. that helped and we got better AFR and HP and Torque numbers. But Frank suggested going to smaller jets on the primary and secondary jets. So I switched them both out to 150's from the 160's. This time we hit it on the money. It should be said that I had the opportunity to use Franks knowledge, equipment and shop to dial the car in. I used his digital sync tool to get my carbs perfectly synced. Then I used the Lamba sensor to properly set the idle mixture. Now my car idles at 600 RPM, not 1200 RPM. Final results, a totally flat torque curve, and smooth power with way crisper throttle response. In the end, we came up with 153HP and if I remember coreectly 114 ft-lbs of torque. Not the numbers I was expecting by any means. this car runs great. And just for data purposes, a stock efi 13B only makes 135Hp at the flywheel. And a Turo II only made 156HP at the flywheel. So I am not unhappy. Afterall, the stock 12A only made 101HP and 107FT-LBS of torque. So I have certaily made a huge gain. I knew the car would break 110mph in third gear, but I didn't exactly to what extent. After the first few runs I did see the mph measurements were on the money with RPM that I see when I'm driving on the street. In third gear when I did a full 9000 RPM run it hit 122 mph. One of the most important discoveries during the testing was the location of the power band. I've always felt this car pull hardest starting around 5000RPM, and it does indicate that on the dyno sheet. What I did not know was the horsepower begins to drop at around 8200RPM. So I don't need a 10,000RPM tach, SO I switched the car back to using the stock tach and I will be removing my Autometer Carbon Fiber tach. I think I'm going to hold onto it until I install the efi. Who knows, maybe efi will yield power above 8k. I will post the dyno sheet when I get it. I forgot to email it to myself when we were done today. I had to get to a job in the afternoon. SO in the long run, I know where it stands, and I know my AFR never strays below 12.4 or above 13. Which is very smooth for a carbureted engine. I couldn't have figured all of this out without Frank's help. Thanks Frank! The car is so much smoother and rsponsive on the road now I am shocked. And the tire chirp at second gear is a little bit longer.

Huzer21 · Postby **Huzer21** » Sat Jun 14, 2008 9:14

Sounds like a very fun few days of tuning/troubleshooting, and getting good results in the end. Congrats, and kudos to you and Frank!

goldrocket · Postby **goldrocket** » Sat Jun 14, 2008 9:14

Thanks, and it was fun. I always learn something new when I go to Frank's shop.

4doord · Postby **4doord** » Sat Jun 14, 2008 9:14

Where is he located and how much per hour on the dyno time? That alway's sucks when the number's you think your going to hit are incorrect, I've been there.

goldrocket · Postby **goldrocket** » Sun Jun 15, 2008 9:14

I will talk to him tomoroow and get an hourly rate and his rate for a complete dyno tune. He's not expensive.

GR-8 · Postby **GR-8** » Sun Jun 15, 2008 9:14

Those are pretty good numbers. Up there with some of the 8's that dynoed.

And you hit 122 in 3rd. Our speed in third at 9k is 90MPH. I think you should hit I-25 with an 8 down there. I think it'd be really close. Your 7 is lighter I believe so who knows who'd come out on top.

Postby **RX-7 Chris** » Mon Jun 16, 2008 9:14

Not as high as I expected but still very good numbers. I need to take my car down to him. I also would like to find out what it would cost.

Stealth01 · Postby **Stealth01** » Tue Jun 17, 2008 9:14

Congrats, Al! What's important is that you are happy driving it, right? The rest is just eye-candy.

MS3_Mafia · Postby **MS3_Mafia** » Tue Jun 17, 2008 9:14

Nice numbers, cool you got it all tuned!

goldrocket · Postby **goldrocket** » Thu Jun 19, 2008 9:14

If anyone is interested in setting up a dyno time with Frank at SR Tuning he is a member here. You can message him under screen name SR-Tuning or go to my profile, he is on my friendslist.
SR-Tuning

Finally got the time to go dyno my car

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