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petert

[Race_Prep] Never Ending Race Car Build

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welshpug

that is not far from the standard spring rate so standard or 20mm bars, pts gravel setup was 185 and 20mm, tarmac 225 and 21mm.

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petert

If you ever think you'll go near a race track, use 220-250/21mm. Otherwise 150-200/20mm. However, don't be concerned about using 21mm bars with standard springs. It works well.

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Andy

Wow. Thanks very much. So a slight increase in spring rate at the rear is a potential improvement . That is very helpful.

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petert

A great pic from the weekend. Front fully loaded on 500lb springs, rear wheel in the air as usual, on a high speed sweeper.

post-2864-0-17496600-1493713217_thumb.jpg

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petert

Increasing rear springs to 650lb made a significant difference. Thus increasing the front to 650lb to square it back up.

post-2864-0-60722500-1501727565_thumb.jpg

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camgti

Nice one Pete. Are you seeing improved lap time from the changes or ease of consistent lap time?

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petert

Indeed both!

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Andy

I will display my ignorance here by assuming that with the spring rates you are using, there is almost no suspension movement at all, which is presumably you are trying to achieve to enable the road/tyre contact to remain uniform as the chassis changes direction?

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petert

At the g's we pull there's still a lot of suspension movement, even with 500 front / 650 rear combination. Way too much body roll. Look at the pic in #80. So yes, trying to keep contact uniform.

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Andy

Yes. See what you mean. The centripetal loads must be pretty high!!!

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petert

I've been fighting a niggling miss above 6500 all year. It's finally got to me. I've replaced plugs, coils, leads, ignition harness and had the CDI overhauled. I've also replaced the alternator with a new 35A item. Hopefully that's every possibility and it will perform flawlessly in the race on Sunday.

post-2864-0-74614100-1506675572_thumb.jpg

post-2864-0-29214400-1506675597_thumb.jpg

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petert

A very frustrating day with three DNF's from three races. The niggling miss starts at 4000 now is there all the time now. I've tried everything and I'm at my wits end. I now suspect the ECU is faulty in some way. Perhaps a heat/viabration issue. It's off to a higher level expert now.

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wicked

Sounds like spark plugs.. have seen it more than once that an engine started to misbehave at higher rpm after spark plug change. Caused by broken ceramic (due to dropping on the floor at the shop?) and results in firing via the cracks at high temperature and rpm.

Did you exchange the parts one by one with test drive inbetween? Best way to find a faulty component.

Edited by wicked
  • Like 1

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JeffR

When I changed from a sausage filter drawing air through the slam panel to a proper airbox (via the lhs headlight) I had a distinctive miss in the upper revs like yours.
Was identified as a reverberation within the airbox messing with the map sensor, so a restrictor was placed in the line which cured the problem.

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petert

I have thrown so many sets of plugs at it, in addition to completely replacing all the ignition side just last week. The signal looks good from crank angle sensor, all that is left is the ECU.

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wicked

Won't be the plugs then. Probably you already have digged through the log files to see if you have strange oscillations on the MAP as Jeff suggests?

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B1ack_Mi16

Running map sensor at all apart from barocorrection?

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petert

The ignition is mapped via the MAP sensor. The induction shape/design hasn't changed in 12 years. I doubt it's that. Further to my fears, whilst trying to move the cars around in the shed today, the CAN bus didn't connect between ECU and the dash first go. It took several on/offs to make a connection.

Edited by petert

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Thijs_Rallye

Time to open up the ECU then. Maybe it's just cracking solder joints if you're lucky.

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petert

I got the ECU back from Haltech yesterday. It had a "ground leak". Thus being unable to ground out the injectors as the RPM and current increased. All fixed now.

 

It's a five layer board. I wouldn't have had a clue where to start looking.

Edited by petert

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Thijs_Rallye

A five layer board is indeed way beyond the DIY scope. Good to hear Haltech was able to fix it.

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mmt

That was the reason why I have been hesitating to move away from good old 45 Webers. I am now on Electomotive management crossing my fingers.

 

Good to hear you are back in business Peter.

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welshpug

its very rare an ecu gives any trouble, whereas your Webers will always need fiddling with :P

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petert

I think it's fair to say it's my fault. Family and friends have reminded me of two mishaps. One, I forgot to attach an earth lead on one occasion. Two, a battery melted and caught fire during a race.

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petert

I've made the decision to jump from 205x50/15 to 225x50/15. The difference in diameter is the real killer. I have to perform considerable body work to make them clear the front bumper bar when running 6 deg of caster. I'll post some pics over the weekend.

 

Additionally, the difference in diameter is 3.5%, equivalent to half a cwp change!

Edited by petert

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