R&P what to go for, 3.68 vs 3.94

[corrado9a 0]

Hello all

 

I know that the ring and pinion mod has been debated numerous times, but i have found very little information on the option of going down to the r&p from a KR engine.

 

The question is because in the US people seem to like the option of going down to the short gearing, but we Europeans like better what they actually have on their corrados, the 3.68 option. (you know the grass is always greener on the neighbor's yard). I am afraid that going down to a 3.94 may be too radical because the European Cs have a shorter gearing in first and second compared to SLCs and what they think is tractable may not be suited for european cars.

 

My car has all the usual mods for a NA car, VGI, straight through exhaust, flywheel, cams, ported head... and i am not that concern with top speed as I suffer from police persecution mania (is that right?) and i tend to cruise at legal speeds on freeways.

[s1m0n 0]

First question, do you actually have a 3.68 in your box?

 

Most VR's seem to have come with the crappy 3.39 (which is one of the reasons they feel so "lazy" in stock form), though I guess I'd add the caveat that I'm talking about the UK of course.

 

In my opinion changing the FD (Final Drive) ratio is one of the most underatated mods you can do, changes the whole "personality" of the car.

 

Cheers for now

 

Simon

[corrado9a 0]

Upss

Sorry, I should have explained my self better.

 

MY ABV has standard box, hence the 3.39 long gearing.

I am going to change that to a shorter one, just debating to which one: 3.68 vs 3.94 and of course throw an LSD in the box.

Edited May 10, 2012 by corrado9a

[s1m0n 0]

That's not an easy question to answer as it's very subjective! Personally I've tried both (and am currently thinking about which to put in my new VR6 lol...), I would say that either are streets ahead of the 3.39 though.

 

If you go with the 3.68 the KR 5th provides a slight OD 5th effect and if you choose the 3.94 a diesel 5th can provide the same service, you do end up with a fairly big gap between 4th and 5th though!

 

My personal feelings would be 3.68 for a daily... But I know plenty of people would disagree with me ;)

 

As for the LSD, yea a no brainer whatever the FD

 

Cheers

 

Simon

[coullstar 0]

3.94 would be a bit to far IMO. 3.68 is certianly worthwhile andas said brings the car alive added with a G60 3rd gear as well as 3rd is too long in a VR.

[Kevin Bacon 5]

Wow, haven't seen you around these parts for ages S1mon :D

 

SLCs got the 3.68 as standard. Probably to make up for the fact it got the emissions strangled 2.8 instead of the euro 2.9.

 

And Europe got the 3.39 to probably get some kind of economy out of it :D And to get that headline 146mph top speed of course!

 

I thought 16Vs already had a low geared R&P?

 

Have to share your sentiments with the 3.68 in VR6s. I've used it in a standard VR6, a VR6 turbo and now a R32 conversion. In the case of the latter two, there is always vivid acceleration in any gear at any rpm. One of the best mods ever!

[s1m0n 0]

Hi Kev, I'm back in a VR6 after far too much messing about with jap stuff ;) how goes things with you? R32 now I see, on DTA & with the drive by wire too, very nice!

 

16V's do come with shorter ratio's but he said "my ABV has std box" so I think we're all assuming he's in a VR

 

I though you were running a Gemini now though, your still on the 3.68, you've got an LSD though, right?

 

I think it was PhatVR that always said the 3.9 was better, better on track I think I'd agree but I think the 3.68 is better on the road, and with 17" wheels and a little tuning it'll pull 150 anyway :D

 

Cheers

 

Simon

[Kevin Bacon 5]

Yeah I missed the ABV comment, whoops!

 

I pulled out of the Gemini GB in the end. I convinced myself that £1350 was a lot of money for a few gears and that the 02M was a far cheaper and more widely available solution....until I looked into the faff of fitting it, that was! So I'm still on the car's original 02A at just shy of 200K. Which has seen 350lbft+ for over 4 years and now R32 torque. A testament to VW's over engineering! Yeah I've got a Quaife LSD. That poor thing has seen well over 100K's action too and still going strong.

 

Yeah I remember Phat saying something along the lines of struggling to get more than 125mph out if it with the 3.94!

 

I find gears that short a pain in traffic. It seems to augment drivetrain shunting coming on and off the gas in 1st and 2nd.

The 3.68 as you right say is the best compromise.

 

Yeah Mr DTA is running the R32 engine exactly as VW intended, less the MAF of course. But I have more control over the torque curve, which is nowhere near as aggressive low down as the factory car. The inlet cam VVT was fun. I'd love to see what algorithms VW use to control that as even switching oil viscosity completely throws my PID loop!

[s1m0n 0]

Yea the Subaru ECU has some pretty complex stuff looking after VVT, if you can keep them (it) locked till the oil is up to a certain temp that might help your stability.

 

Umm bit off topic lol... sorry!

 

I think if your gonna run "short" gears in a road car you'll need to keep the flywheel weight standard or thereabouts, lighter ones usually exacerbate drive-line shunt.

 

Cheers

 

S

[Kevin Bacon 5]

LOL, yeah, just slightly. Unfortunately the DTA can only delay VVT engagement via water temp, not oil temp. Should be just a quick firmware tweak if I ask them for it. OK, I'm done with the geeky stuff now :D

 

That's a good point about the flywheel and I deliberately put the standard 'heavy' one back in when fitting the R32 engine. That kind of off idle responsiveness plus a light flywheel, plus short gearing = traffic nightmare!

[s1m0n 0]

I'd suggest making that change (to oil temp based delay), it should help.

 

I've run a light one with a 3.68 and you can feel the difference when you just "rolling" in traffic, for me, I'd say keep a stock flywheel if your doing more than a couple of thousand miles a year on the road.

[corrado9a 0]

I am using a lightened flywheel with a ceramic clutch disc already so, that makes the decision easier. Safest bet for drivability is 3.68 then.

 

Thanks for the feedback, I appreciate the help.