FWD highway dominance- Fact or Fiction? Options

[KOU In3]

OK, it's come up indirectly a number of times but am I the only one that questions this whole FWD highway ownership thing? It seems like it's become an accepted fact that the FWD's are 50% faster from a roll.

Yes, the AWD weigh 400 or so pounds more.

Yes, there is an AWD drivetrain loss.

BUT, turning the AWD components only saps power to a point. I'm not sure I buy into the hype of 400 flywheel HP turning into 300whp as compared to it only losing half that amount in a FWD.

At stock turbo power levels yes, I can see the difference there but when you start really modding things I'm less certain.

This is when I'm waiting to hear the FFF cars (factory freak FWD cars chime in) with some arguements.

*Beware, the "Marucs at 12.6" arguement I plan on countering with though. *

[awd4kicks]

I used to have this argument until one day some time ago when Nate's FWD Eclipse had similar mods to my AWD. At the time I was probably laying down mid to high 13 second passes at best, but I could easily beat Nates front wheel drive from a dig though he was coming on like a bat out of Hell at the end of the quarter.

This particular day Nate and I went at it from a roll around 20-30mph. To my dismay, he INSTANTLY left me 2-3 cars behind struggling to get up to his acceleration level. It was rediculously obvious at the FWD vs. AWD rolling advantage.

My fix was more HP and tuning, so I could run with a fairly built FWD like nate's was set up at the time and still launch like a mofo in a dig.

[KOU In3]

This is the common scenario that I think plays out though. Here's how I benchrace it.

300 fhp FWD = ~255 whp @ 2700 pounds
Each hp lugs around 10.58 pounds. Given a 15% drivetrain loss.

300 fhp AWD = ~231whp @ 3100 pounds
Each hp lugs around 13.41 pounds. Given the traditional 23% drivetrain loss.

Obvious the power to weight ratios are hugely different here.
10.5:1 and 13.4:1 (actually wieght to power ratio but you get the idea)

The above scenario is where I think the reputation stems from. But I question losing 23% from a 400-500 hp level.

I'm off to check trap speed and turbos at dsmtimes.org to add fuel to this one.

[Rollout]

I constantly got owned on the highway(car length or two) by my friends 1g fwd, All he has is a boost controller set at 16psi and an ACT2100, other then that, totally stock. Then again, i was running 15psi, smaller turbo, more weight, drivetrain loss. The mods i had then were upper and lower I/C piping, bov, catback, spec stage 3 clutch, k&n filter...
For reference, I ran 14.066 at the track, he ran 14.3 something

[MidwestDSM]

I've noticed that my FWD picks up pretty well from a roll...wanna test out this FWD dominance issue with me Travis? Mines pretty much a stocker.

[JMoushon]

1G fwd, 14b, 17psi, 3"dp/side exhaust, 2G tb elbow, no fuel control, 255 Walbro, 2.5"uicp.

Runs dead even from 30-85 with

1G awd, Big 16g (not perfect), 20psi, front mount, MAFT, 3" turbo back, etc.

I have not raced any sub 13 sec awd cars, but I have also never been left from a roll. The White FWD took down a modified STI from a roll. I have, like Spy and I'm sure others, owned modified versions of both DSM configurations. I ran 13.6 in my last blue awd, and Josh(Slo-Pny) blew by me at 100 like I was in reverse in his fwd. I believe that awd cars will never be beat out of the hole, mod for mod, but a fwd will always win from a roll, mod for mod. Just my .02

[KOU In3]

From a 14B standpoint I can see it. As per the example I outlined. What I'm wondering is for instance a BR580 set-up on each.

The drivetrain loss and 400 pounds make a big difference at the lower hp levels. But is this going to hold up when both are running 20G or bigger turbos and have at least some basic weight reduction (bumpers, AC, PS, etc.)?

[akamiami]

I leave fwd's and rwd's from a roll, but then again, I'm light. It's tough to compare a car solely based on the modifications because you rarely get the chance to place two cars that are all that similar except for the drivetrain.

I have seen FWD's consistently run down AWD's at the shootout though. It was sad, you'd swear that the awd was going to win by a landslide and then the FWD would use the last 1/8 mile to make the AWD look like it was coasting.

[Coiled]

Take that dash back out?

[Rollout]

To give you guys another idea... My friend (fwd gst from above) and I went at it again from a roll tonight (about 65mph)... He got the jump so he was already a bit ahead of me, but through third i caught him, and fourth gear just walked away from him.. that was with my stock downpipe and stock injectors at 12 psi

[JMoushon]

KOU, you may have a point of reference soon enough. Next on the list is a big turbo. Not Big16, more like the aforementioned 580 or something similar. I know full well that I will never hook, but it should be a blast when I finally do. There have got to be 14b AWD cars on here that are similarly modded to either Spy or myself. If there are, we will look at e.t. and trap at SCDC and use those as starting points of reference.

[awd4me]

i dont see how you think mods are going to change the percentage of horsepower lost kou.....atleast thats what it seems like your saying....

[JMoushon]

I believe that he is implying that once you reach certain hp levels, 400, 500, etc, that the parisitic loss would be less of a percentage and therefore less of a factor. I am inclined to agree, simply because: If you take like-modded cars, awd/fwd, on a 250hp tune, there may be quite a bit of difference in roll-on acceleration. Conversely, the same cars at 500hp, because of the sheer power, would feel more similar.

[Benny Z]

I leave fwd's and rwd's from a roll, but then again, I'm light.

how light?

[natedogg]

A post of mine from a couple of years ago on this subject. This is also after I had recently destroyed a turbocharged integra from a roll on the interstate in my 16g'd AWD.

This is when Josh had his fairly well modified fwd.

Funny that you mention logging Josh's car though. Because that is exactly the reason I was out at his place. We tuned out most of his knock until he was seeing 17-18 deg. of timing throughout. There is no doubt it was running strong. He's the more experienced driver too, though when racing in a straight line from a roll I don't think much driving skill is required. I went all the way to 110 mph still pulling on him. Now maybe if we had shifted to 5th and gone to 140 he would have started reeling me in. I have too often heard that all things being equal a FWD will pull on an AWD from a roll. Well in this instance all things were not equal. Josh's FWD had mods on me and I still pulled on him from a roll. Hence my reasoning that drivetrain loss becomes negligible once an AWD DSM starts getting modded more and more.

If you think about it, it makes sense. As you start modding a car you don't lose more horsepower due to drivetrain loss in proportion to the HP that you add. That would mean that though it took say 40 HP of drivetrain loss on a 200 HP AWD to get the tires moving on a stock car (assuming 20% drivetrain loss), it now takes 80 HP of drivetrain loss on a modded 400 HP AWD. I can't believe that drivetrain loss would increase linearly with HP. It doesn't make sense. I think the percentage of drivetrain loss decreases as you start modding a car. I think it remains a fixed number of 40 HP or maybe increases a little bit due to increased heat dissipation due to more power moving through the flywheel and drivetrain. So, accordingly, the 400 HP car would have say 10-11% drivetrain loss now.

Let's do the same thing with a FWD car assuming 10% drivetrain loss. 200 HP * 0.1 = 20 HP drivetrain loss. With my reasoning the 400 HP FWD should still be seeing only about 20 HP or slightly more of drivetrain loss at 400 HP. That translates to about 5-6% drivetrain loss. So now on two equally powerful modded AWD and FWD the drivetrain loss differs between the two by 5% rather than 10%. This difference will continue to shrink as both cars increase in HP.

[KOU In3]

That's pretty much EXACTLY what I was driving at Nate. Sure there will always be some additional power lost due to the friction and increased moving parts. But, I expect a lot of the parasitic loss to be just the base amount of power required to move all the additional parts.

To take it the other way, I'm really doubting that if we put a 5hp Briggs and Strattion motor in an AWD that it would only losed 1.2hp. My poing being that if it's less of a percentage and more of a base plus (as per your 40hp + 11% guestimation).

I'm looking less at a mod for mod, 14B trap speed comparison here. More of this: Yes, a basicly modded GST is a good highway contender for the money. BUT, does that advantage remain when it's a highly modified beast competing against other high HP AWD cars?

My vote is that the discrepancy fades way back as the cars double and triple in hp levels. But I'm hoping to find out at some point.

Ironic that I was inadvertantly bringing your post back from the dead though too.

[JMoushon]

God stuff, Nate. I guess that is very similar to what I was trying to say, but I lacked the motivation to elaborate as much. However, after the drivetrain loss becomes a relative non-issue, what becomes of the inherent weight disadvantage? It would seem that once a car reaches 400hp, 400lb would make less of a difference, but add 400lb to what is still roughly 5% less wheel hp, and logic says the fwd will still walk away. I believe this whole issue is very subjective, and that it stems from the fact that the two configurations feel completely different. It has always seemed to me that the fwd cars have more "legs," and that they accelerate harder in the top three gears.

[akamiami]

how light?

2500 lbs

[natedogg]

God stuff, Nate. I guess that is very similar to what I was trying to say, but I lacked the motivation to elaborate as much. However, after the drivetrain loss becomes a relative non-issue, what becomes of the inherent weight disadvantage? It would seem that once a car reaches 400hp, 400lb would make less of a difference, but add 400lb to what is still roughly 5% less wheel hp, and logic says the fwd will still walk away. I believe this whole issue is very subjective, and that it stems from the fact that the two configurations feel completely different. It has always seemed to me that the fwd cars have more "legs," and that they accelerate harder in the top three gears.

I agree. The weight issue is always apparent. My post was focused more on the drivetrain loss issue. Given equal hp, lighter is quicker, no doubt.

[natedogg]

Ironic that I was inadvertantly bringing your post back from the dead though too.

We've come full circle now.