Not Broken Yet, But... Max Revs + LatG

Fiat 500s that Do it Naturally.
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Scallootch
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Not Broken Yet, But... Max Revs + LatG

Post by Scallootch » Fri Sep 21, 2018 4:10 pm

So this probably isn't the best: since I still haven't found a source for C514 ratios from a 1.2 model I'm stuck stretching 2nd gear about 200RPM past redline in one section of my favourite track. Here's the data with a map pinpointing that spot 34s into the lap where I stretch it...
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CAPTURE.jpg (35.32 KiB) Viewed 4786 times
This happens usually 2s after peak .G in the previous right-hander.

SO: the 6750RPM redline definitely does not have a 'hard cut'. I'm wondering what the oil feed situation is at this point in the lap. Maybe an oil sample test is in order after the next test day, especially now that I should be pulling more lateral .G on a new suspension and tire setup.

I think I may need to bring my spare motor's oilpan to the fabrimacator for some baffles.

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Re: Not Broken Yet, But... Max Revs + LatG

Post by MadFiat » Fri Sep 21, 2018 4:39 pm

The importance of gear ratio on the NA can't be understated. I originally owned a Sport and thought it was pretty snappy. Top speed around 110. Then I drove a Pop more recently and found that although it was more heavily tuned, it was actually slower and could barely touch 100. Then I compared the gear ratios and realized that at 100 it was in the wrong part of the powerband to keep accelerating. The ratios on the Sport were lower and that gave it just enough extra to the wheels to make a difference.

I concur with you also about the concern about oil starvation cornering at high G. My Abarth's motor lived its life at redline. And it exploded an exhaust lifter. I suspect either the oil thinned or I starved it running redline in 2nd gear up and down the dragon. I had the road to myself for several hours and pushed the car very hard in the corners. It was not many miles later it started showing issues.

How did I get the Dragon to myself? That's another story!
2015 Rosso Abarth 5MT - MAD FIAT - EC Phase 2 + Supporting Mods
2015 Granito Lucente 500T 6AT - Projecto Estupido
2017 Fiat 124 Spider 6MT - Another one???

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Scallootch
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Re: Not Broken Yet, But... Max Revs + LatG

Post by Scallootch » Sat Sep 22, 2018 10:24 am

Sport has a 3.73:1 final drive while the Pop has a 3.44:1; all other speeds 1st through 5th are the same. My spare (hopefully one day track-only) Sport should have the 3.77, and so far I've been using the standard gearbox in the daily+trackday Pop.

The Pop-based B-Spec race cars used "South American close-ratio" gearboxes, which I believe are also C514 gearboxes, but for 1.2L models. On spec sheets for 500, Punto, Ka Mk2 and Panda 1.2 models you'll see that they've got shorter 3rd, 4th and 5th gear ratios. It's that 2nd-3rd gear split that really kills laptime in North American 1.4 nonturbos, hence the gear-stretching to 6900RPM in 2nd in some sections. I believe that with the 'close ratio' 1.2 box and a 3.77 final drive, a nonturbo would be an eye-opener on tight circuits.

I've been in contact with gearbox rebuilders in the UK in hopes of getting internals from one of these 1.2 units with no luck. One well-known and well-meaning good fella in Miami (we'll call him "Schmarlos Vodriguez") said he'd help me source a 'box from Mexico but that hasn't happened. I briefly had a Brazilian co-worker who said he'd get his brother to send a 1.2 Punto 'box from Brazil, but that was all talk.

I've just now emailed RRM, since I just discovered that at least one of the B-Spec cars may have been assembled there. We'll see if they can source me some cogs!

Shadowshaggy
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Re: Not Broken Yet, But... Max Revs + LatG

Post by Shadowshaggy » Mon Oct 01, 2018 12:31 pm

Johnny Santoro in Italy may be able to help you out, he just sourced a Giulia 6MT for one of the Canadians and got it shipped over (just received last week), so hit him up on Facebook.

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Scallootch
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Re: Not Broken Yet, But... Max Revs + LatG

Post by Scallootch » Fri Oct 05, 2018 2:58 pm

Thanks. Got an old friend who's just finished restoring his Alfa GT Junior in the Netherlands, and is currently in the UK sorting the car's shipment back to Toronto along with a couple of spares. Says he'll pick up a C514 geared for 169A4.000 for me from Charles Trent. We'll see...

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