CSX3170 Engine problems

[Cobra #3170]

I finally got the bugs out of the system and the engine works as it should huge top end power and great low end response and drivabilty.
The problems were related to low voltage at the computer because my alternator had an open diode and a burned winding on one of the output circuits. The master disconnect was high resistance at 30 amps but would still start the car. I was loosing 1 volt there, at times the voltage was so low it affected injector opening time and duration. I shunted the stock amp gauge by installing an 8 gauge wire between the starter solenoid (battery) and alternator output terminal.
I still get readings on the amp gauge but not so large as with the stock set up.
I also had a defective 5 wire O2 sensor and after fixing that found that the engine map was really lean between 1400 and 2500 rpm with small throttle angles.

Here is a video of an autox today, unfortunately the mike battery was dead so hardly any sound which is the best part. My driving is not so hot either, way too much steering input but that can be fixed with practice.

http://youtu.be/_yV8NGkZEck

[mickmate]

Hi Bruce, I don't know whether to be happy you've sorted it or scared?! The link didn't work for me but I'm looking forward to seeing the vid.

[Cobra #3170]

Nic,

I can't figure out what is going on with YOUTUBE, I can never post videos that can be seen for some reason, seems that when Google exerted their influence over youtube it quit being easy to use, first it was just a Google pass word, now you have to wade through all their face book wannabe BS to post a video. I uploaded it and checked make public but so far I am the only one to be able to view it. If I knew what I was doing wrong I would fix it but I have no clue. Maybe Ron could tell me what I need to do.

The new engine is really good now, it is responsive even as low as 1600 rpm even with that really low (numerical) first gear, it has a usable range of 20 mph to 90 mph with no shift required and can break traction with a nudge of the throttle at any time. I upped the caster this time around to 6.6 D. but have found that I have to reduce static camber to use that much caster. The car will be cornering perfectly at fairly high steering angles but if I have to add lock it understeers because (my theory) it has so much negative camber between static and caster that it gets up on the edge of the tire.
I am going to take 1 D. out of the front camber and see if that fixes it. If not I will go back to 5 D. caster. I am on street tires now and they have much stiffer side walls and need a little less static camber than Hoosiers.
Maybe this URL will work

http://youtu.be/_yV8NGkZEck

[Jerry Clayton]

Do you ever take tire temps?????????? three spots on each tire as soon as you make a run????????

[Cobra #3170]

I am going to rent a skid pad next month for a day and set up 5 segment timers that will give times through different course elements. We will be taking tire temps, checking contact wear, side wall scrub with different sway bars, springs, pressures and camber settings to get this thing working on street tires. I have already reduced spring rates by 28% but should have pulled some camber too.

[Morris]

Bruce

The best part is you look like you are having fun......and it's always fun when you figure things out.....glad to see the engine is working out....

The skid pad is always a good idea......but go both directions.....as some tracks we will run 51% LR/RF and other tracks we'll run 49% LR/RF....depends on the number of right or left turns......

And Jerry right on.....tire temps tell you everything.....

[Cobra #3170]

I certainly agree on tire temps, I didn't expect the engine to work as well as it did and was planning on making changes to the map etc. It worked perfectly out of the trailer so I just drove it and did not do anything other some air pressure changes. I brought all kinds of engine related stuff but nothing for actually doing handling work but will do it right next time. These cars are so light that they are a handful of street tires, I just need to get the balance right. Need to adjust brake bias too but it seemed pretty close.

Morris, you are right on the fun part, if it was not so much fun I would have quit long ago.

[Jerry Clayton]

Besides the segment timers, have you considered on board data??????????simple Pi system for a kart will record everything from timing to g loads both sideways and long.
even track mapping--------thing about that is that you can defind what area was helped/hindered and also cross check engine rpm, throttle position, steering imput (actually big brother watching driver!!!!!!)

And take scales with you------------

[Cobra #3170]

The car has a Pi system 2 with mini dash and can log rpm, speed, throttle angle,brake pressure, steering angle, g load, oil and water temps and oil pressure. I scale it before I go on a level floor. I don't have a portable scale platform. If we change springs we make the mounts similar side to side and then set corner weights again when home. Segments are much more precise on a short course than the Pi and are what it all about point A to point B.

[ERA Chas]

If you can do some steady state cornering Bruce, love to learn the lateral G's. I know that's tire-dependent also...

[xb-60]

90mph top end in first gear? Wow. Is that a CR Toploader? Can I ask what is the rear end ratio?
Video works for me BTW. Nice and clear too, thanks for posting it.
Cheers,
Glen

[mickmate]

Hey Bruce thanks for sticking with it on the video for us. Thanks for the ride but now I feel a little queasy. Why are you testing on street tires because of the side wall stiffness? Do you think the big caster angle makes it steer like a go-kart where it lifts the inside rear wheel to make it scrub on tighter turns?

[cobrajeff]

Nice video Bruce - reminds me of the days I used to watch you fling that beast around the cones in the Ford Motor Company World Headquarters parking lot!
Please fix the battery, though - would have loved to hear the sound of the new engine!

Jeff

[G-Pete]

Your steering wheel is very confusing. For auto-X I would use a regular circle one. Watch the video and pay attention to your hands...

[Jerry Clayton]

I agree that your segment timers will give you a very good interpetion of results, but, the info from the Pi system will tell you why you had a difference in time(like what was happening in the previous corner) It is not about point A to point B-its about point A to Point B to Point C, etc---------and the Pi system does a super job with a segment print out along with a theorical fastest lap deal--------

[Cobra #3170]

Guys,
Thanks for all the comments and questions, I'll try to answer them here.
Chas the car pulled 1.5 g's on Hoosiers I don't know what it will do on BFG's
I am prepping the car for events that require a minimum of 200 TW tires Hoosiers are 30 or 40 TW.

Nic,
The Hoosiers had soft sidewall that required lots of static camber but deflected enough under barking that tread contact was still good. BFG's are much stiffer in the sidewall so my idea was to go up in Caster from 5 to 6.6 degrees and down in camber from 3.2 to 2.0 to improve braking capability in the front.
I went down on rear bar and up in rear spring ratio's to keep the rear wheels down in a corner and to help corner exit. I am hoping it will be enough to keep the inside rear loaded with high caster values. If not I will reduce caster back to 5.5 D. or so.

Steering Wheel,
The wheel is flat on the bottom to allow my fat knees some clearance, once I get used to the car it will not need all the frantic steering input, that is just poor driving on my part. Total steering is only 3/4 turn lock to lock with the steering rack I am using.

Speeds in low gear I have a dog ring shifted Jerrico 4 speed with a 2.2 low gear and a 3.31 rear, engine is chipped at 8500 tire is around 26.1 tall
This new engine is the best one yet, it comes off the line smoothly and you can easily control wheel spin with the throttle even at 2000 rpm and below.
I let the clutch out a little above idle and give it about 10% throttle and it just jumps out as you can see on the video.

When we test we will be looking at air pressure variations, camber angles,
front to rear roll stiffness and possibly roll center axis for best performance.

These tires are a real challenge with a light car because it is hard to get mechanical grip from having the tire conform with pavement variations,
the Hoosiers are so soft they just hook no matter what, the BFG's are a much harder compound but rules are rules so we need to do the best we can.
I am really pleased with steering response the BFG's are very crisp on turn in.
and ultimate grip is good too for a 200TW tire. I think they would be a good street tire but not so good in heavy rain because of tread depth. If I were
driving in the rain I think the Michelin pilot super sports would be very good.

I'll try and post the results after the next test along with a video with sound,
I put new mufflers on because of numerous complaints about noise levels
and they are a bunch quieter for now (glass packs).

Tires size went from a 295x18 front to a 315x18 front the rears are 335x18 as before but wider rims front and rear 11f and 12.5 r. Toe is 1/8 in at front and 3/16 in rear.