VW MK2 GTI suspension upgrade/questions
Posted by Kristof
Wilson von Kessler Elite Moderator Location: Lookout Mountain, GA Join Date: 02/28/2006 Age: Possibly Wise Posts: 1,127 Rally Car: Colts are in Finland; now '87 325i, '89 325i |
Grant Hughes Infallible Moderator Location: Whitefish, MT Join Date: 01/11/2006 Age: Midlife Crisis Posts: 6,818 Rally Car: BMW |
Kristof Kiraly Professional Moderator Location: Aliso Viejo, CA Join Date: 04/07/2013 Age: Settling Down Posts: 14 Rally Car: 1986 VW GTI |
Paulinho Ferreira Godlike Moderator Location: Charlotte, NC Join Date: 03/15/2007 Age: Midlife Crisis Posts: 721 Rally Car: Honda Civic |
The TDI cant be all that bad for rallying due to its powerband since its going to feel just like a restrictor car. Plus Michael seems to do just fine.
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Wilson von Kessler Elite Moderator Location: Lookout Mountain, GA Join Date: 02/28/2006 Age: Possibly Wise Posts: 1,127 Rally Car: Colts are in Finland; now '87 325i, '89 325i |
John Vanlandingham Mega Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
Josh Wimpey Professional Moderator Location: VA Join Date: 12/27/2006 Age: Midlife Crisis Posts: 649 Rally Car: Sneak the Golf |
John, serious question regarding the TDI idea and traction problems due to torque...
What is the difference between running a 160hp 160tq gasser with a low final drive (to multiply the torque as you so often remind everyone) and running a 160hp 260tq TDI with higher gearing? Doesn't this solve at least one of the problems with the expense of a fancy final drive for modern FWD gearboxes? If you can just use the stock gearing because it is good enough considering the torque and it's delivery throughout the powerband? From my calculations, it looks like a good gearbox for 2nd-5th compared to a 16v 'close ratio' box with a 4.47 Final Drive... 1st gear is useless in both of course aside from pulling on the trailer.  ____________________________________________________________- One. Class -- 2WD www.quantumrallysport.com http://www.facebook.com/home.php?#/pages/Quantum-Rally-Sport/281129179600?ref=nf |
Out of this dumpster fire Mod Moderator Join Date: 08/15/2010 Posts: 1,236 |
Josh Wimpey Professional Moderator Location: VA Join Date: 12/27/2006 Age: Midlife Crisis Posts: 649 Rally Car: Sneak the Golf |
Josh Wimpey Professional Moderator Location: VA Join Date: 12/27/2006 Age: Midlife Crisis Posts: 649 Rally Car: Sneak the Golf |
OK, I added top speed in each gear at redline. Still looks pretty good considering both engines have relatively flat torque curves across the usable RPM range.
 ____________________________________________________________- One. Class -- 2WD www.quantumrallysport.com http://www.facebook.com/home.php?#/pages/Quantum-Rally-Sport/281129179600?ref=nf |
John Vanlandingham Mega Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
Josh not sure I'm following , read this 3 times and the only thing that jumps out is the bit bolded bit.. Did you notice what Paulinho mentioned about "restrictor motors"? What I've seen of typical dielsel torque curves they look like a mirror image of a gasser HP curve.... Here's some typical thing: 
Seems to be a whole shit ton at very low rpm then fades rapidly.. And with a whole shit-ton, coming in suddenly, grip---thru just 2 wheels is a problem, and that is what SBD said... Gassers make less power initially and build up as revs increase...as we all know. Gearing multiplies but the net effect is different...hard to splain simply--especially when I'm supposed to be working AND minding the girls who are off from school this week.. Basically "it ain't what we're used to" and so the sloutions "ain't what we're used to.". And if a place with a lot more resources would say in interviews that they had a LOT of difficulties, what will the poor bastid here have? Possibly a slow car John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
Justin Carven Mod Moderator Location: Portland OR Join Date: 01/21/2009 Age: Midlife Crisis Posts: 86 Rally Car: '79 VW Rabbit TDI, '02 VW Golf |
Don't mean to go too far off topic but I saw the TDI discussion so I figured I have to jump in. I've been running my Rabbit the last 4 years with a MK4 TDI engine (ALH) converted to mechanical injection and turbo control. The vane actuation is nowhere near as refined as it would be with the help of an ECU but still does pretty well with a simple Forge adjustible pressure actuator.
I finally have my new MK4 TDI finished and gave it a shakedown at Rallye Perce Neige in Feb.. It was hard to put the power down on polished ice but we'll get to see how it handles with traction at the Empire State Rally next week. I expect it'll take a bit of time to get everything dialed in. I think Josh is going to have a great combination, starting with a proven MK2 platform he's been fine tuning for years and adding the tourque and reliability of the TDI. 
 www.DMackTyresUSA.com |
Josh Wimpey Professional Moderator Location: VA Join Date: 12/27/2006 Age: Midlife Crisis Posts: 649 Rally Car: Sneak the Golf |
I don't think this problem is unique to diesels. Every turbo 2wd car has a similar problem because the torque and horsepower can easily more than double within a narrow rpm band of just a few hundred rpm. It seems to me that where it occurs within the rpm band is less consequential than how quickly it occurs.
If you are in 2nd gear and boot it from 3000rpm in a turbo gas car you may go from 0psi boost and maybe 65tq to 25psi and 300tq by 3400 rpm. So, it seems to me that traction and boost control strategies would be useful in either situation. Everyone I know with a turbo 2wd rally car has struggled with this --- particularly if they are FWD where sudden wheel spin means sudden loss of steering.  ____________________________________________________________- One. Class -- 2WD www.quantumrallysport.com http://www.facebook.com/home.php?#/pages/Quantum-Rally-Sport/281129179600?ref=nf |
John Vanlandingham Mega Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
Yes, that is sorta the direction i was thinking.. And there the thing will taller gearing on loose/slick---(think clutch slip, its kinda the effect I'm struggling with....) It seems to me that a sudden surge/loss of grip is harder to catch (the consequences of) when gearing is taller---or if in a say proper rally car, when in higher gears.... Clutches slip more readily in 4th-5th than in 1st and 2nd... And I know from the one time I was at Perce Niege that spin in 4th gear and I was rotating around a full 360 spin before I could react--except to shrug.. So a stockish turbo-diesel hitting pretty hard just off idle means grip is a problem more than what we're used to.. (You boys should know I lurv diesels and extra Heart turbo diesels. I believe that was a match made im Himmel. [angelic choir UP} But not on gravel in a 2wd car with the resources we have... Or I should say "In a VW I do not see the advantages over a nice DOHC gasser." John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
Wilson von Kessler Elite Moderator Location: Lookout Mountain, GA Join Date: 02/28/2006 Age: Possibly Wise Posts: 1,127 Rally Car: Colts are in Finland; now '87 325i, '89 325i |
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