Ford Forums banner

1 - 20 of 51 Posts

·
Registered
Joined
·
378 Posts
Discussion Starter #1
I would like to know why the V6 VN commodore automatic seems to be quick? For example my Faclon straight six cylinder XF EFI has Power: 121kW at 4000rpm and Torque: 325Nm at 3000rpm the Commodore VN EFI has power: 125kW @ 4800 RPM torque: 292 Nm @ 3200 rpm it has 4 more Kw yet it goes quicker than my XF, my XF only weighs a little bit more than the VN, so weight isn't an issue. Its not a lot quicker..but still only 4kw makes that much difference? I doubt....

Is it something to do with the gear ratio...the differential maybe? It cant be the fact that my XF is a 3 Speed Auto, and the Vn's is a 4 speed auto, because the 4 speed is only overdrive/economy, so you actually lose power if you use overdrive, so really the Vn is actually a 3 speed like mine (if you drive the auto manually) I know the VN revs higher....I also heard the VN's first gear is geared higher, so it revs out faster....?

The VN does (Manual)
0 - 100kph - 8.1 seconds (3.8L V6)
Quarter Mile - 15.7 seconds (3.8L V6)

The XF EFI does (Manual)
0-100km/h: 9.5 seconds
Standing 400m: 16.6 seconds

I know its only a little over a second quicker, which is a lot in terms of racing, but it is only 4kw power difference, with the XF EFI having low down torque and more torque.

This one has always baffled me, as I know the VN isn't super quick, but I just dont see how an engine with 4 more kw and less torque can be that much quicker? The VN is also faster than a VS/VT.

By the way, they are stock standard engines.
 

·
RACE
Joined
·
2,950 Posts
It would be the gearing. Even then I have never heard of a standard V6 VN do 0-100 in 8.1sec. More like 10.1.
 

·
I want my brothers car.
Joined
·
258 Posts
those quarter times seem a little too quick....correct me if i'm wrong.
other than that...i don't have an answer to your questions, sorry
 

·
Two SC 61's = trouble
Joined
·
6,360 Posts
There torque converter is alot looser.1st gear seems to be lower ratio as well...
I guess it comes down to refinement as well? You are comparing an older model Ford to a newer Commodore...
V8's back then where lucky to do those times...
 

·
Registered
Joined
·
75 Posts
I would believe the 8.1 second mark when these were new. VN's are great cars for an old car if you look around and pick up one that has been cared for. In my opinion they are superior in every aspect when compared to an XF. And so they should be when you consider that the XF is the last of a generation of cars that started in the early 70's. I own an XF auto(not EFI) and a VN auto so I should no. Although the VN's motor is rough, course and unsophisticated it's performance is outstanding. My XF drives like a slug and handles like a boat when compared to driving the VN. At no point can it compare when it comes to performance or fuel economy. Off the mark VN is incredible for 6 cylinder motor - it puts both the Ford 4.1 and Holden 202 to shame. When released the VN V6 performance was almost equal to that of the previous models V8. Problem is they are very dangerous in the wet. Just 1mm too much on the accelerator at the lights or when going 'round a corner and traction is all to easily lost. In the later VP's Holden reworked the mapping, throttle, inlet etc to reduce the initial surge of power as too many people had problems with loss of traction. A light arse end doesn't help either. There are really 2 things that make a VN so quick off the mark: 1) They have a surge of torque that comes early in the rev range; and 2) the gear/diff ratio. But once they get upto speed the power surge drops off. The XF's have a diff that is more suited to cruising. Hence the reason they feel so sluggish to drive around town and the poor fuel economy. And, before people start blurting off about how fast and powerful their cars are (Ford or Holden) please remember that I am referring to bog standard unmodified versions of both cars.
 

·
BA'o'Matic 100% working.
Joined
·
3,838 Posts
Gearbox ratios, and diff ratios are in favour of the VN being a quick car ;0)

Jason
 

·
Registered
Joined
·
378 Posts
Discussion Starter #9
It would be the gearing. Even then I have never heard of a standard V6 VN do 0-100 in 8.1sec. More like 10.1.
I don't believe that either, I had another figure of 10.3, but I got the times from here: http://www.justcommodores.com/modules.php?name=VN_Info

those quarter times seem a little too quick....correct me if i'm wrong.
other than that...i don't have an answer to your questions, sorry
Yeah Like I said above I don’t believe it either, even if the VN was brand spankin new. The site I got it on is an "All" Holden site, it wouldn't surprise me if a bit of "tweaking" so to say was done on those times, especially seem as though the webmaster owns a VN.

VN's are great cars for an old car if you look around and pick up one that has been cared for.
Acceleration times I would believe you, but engine wise, I cant agree, I have heard some terrible stories about the VN's engine, really bad oil problems, noisy gear boxes, computer chip malfunctions....they seemed to fix this with the VP however......like you said very poor handling....as one of my mates who knows just all to well about that.....

My XF drives like a slug and handles like a boat when compared to driving the VN. At no point can it compare when it comes to performance or fuel economy. Off the mark VN is incredible for 6 cylinder motor - it puts both the Ford 4.1 and Holden 202 to shame.
The XF EFI was/is a great motor, it has great power figures, and absolute supreme torque figures, which wasn't matched for years by both Ford or Holden. Its also very reliable, as I also know many people who own both EFI’s and carby models, they did sell 278,101 of them remember. One of the best selling cars in Australia. You are right about the fuel consumption, it is much higher than the VN. The XF's handling is quite good I think, I haven't had any major problems with mine, no slipping/sliding even when I really bash it around a corner....on the other hand, one friend of mine loses it quite easily in his VN, and my other friends Executive really loses it....you have to remember the VN was meant to carry over the Nissan straight six engine (of course GM came to the rescue), and was designed thus for it, the engine bay can be considered a very tight fit, and the handling on early model VN's (first year 1988) is very poor, as you read in some magazines warning about getting a "first year" second hand VN.

Off the mark VN is incredible for 6 cylinder motor - it puts both the Ford 4.1 and Holden 202 to shame
Remembering its only the auto that seems to be so quick than fords auto, the XF manual is only a slight bit slower than the VN's manual. 1 second isn’t really that quick, but I do see where you are coming from. The VN is a later model than the XF, and does use more advanced technology (donated/courtesy of GMH) than the XF.

The XF's have a diff that is more suited to cruising.
That’s exactly right, they are a car for cruising, they have longer rods than jap cars and Holden cars, and therefore don't rev as high, but are always have higher torque, especially low down. You are wrong about that’s the reason they use more fuel, they use more fuel as they are a larger engine, weigh more, and don’t use as "sophisticated" computer management than the Vn's, we are talking 1984 technology remember, compared to four years later 1988 technology, think what happens technology wise in terms of computers. A jap car or holden car will always use more "fuel" when accelerating, like on a freeway, as they rev higher, and faster.

Thanks for the info guys!
 

·
Registered
Joined
·
670 Posts
My 2000 1.8 laser can take a vn! If you look at your power output your making max power at 4000 rpm, the vn at 4800 rpm. during a 0-100 and quarter mile races you only use the torque rich ford in first, then your prolly outside your power band for too much of the rest of the race. The vn makes power in a more usefull rpm range for racing (when compared to the xf). But for street driving the xf is the better car, horses for courses! That and you have the dynamics and aerodynamic issues!
 

·
Registered
Joined
·
378 Posts
Discussion Starter #11
There are really 2 things that make a VN so quick off the mark: 1) They have a surge of torque that comes early in the rev range; and 2) the gear/diff ratio. But once they get upto speed the power surge drops off.
So really if I got a higher geared diff, I could almost match the VN's speed/take off, if I then got extractors + sports exhaust I would beat the VN 0-100km and down the quarter mile, and if I got a lumpier cam, or my cam grinded then I would destroy the VN.
What could I do to match the "surge" from the torque converter....there isnt really much is there, as I cant change the torque converter on my 3 Speed Borg Warner auto, or any auto for that matter?
 

·
Registered
Joined
·
670 Posts
I question how much weight is a lil bit? When i used to misbehave with my mates in melb. We'd argue about who gets to carry the extra passenger when we went out!!! 50kgs can make a difference. At one stage during our mod stages between his car and mine the dif between victory and loss in a friendly fling of throttle happiness was who had the extra passenger or even who had the (no racist comment) light asian mate onboard (about 55kgs) and who had the euro mate on board (approx 100kgs)
 

·
Registered
Joined
·
670 Posts
Why no change stall? I think the diff gears will make a big difference, the cam is a good idea to move power up the band as is exhaust and extractors. Be carefull not to mess up the exhaust as when i first fitted the 2 1/2 system to my el it went slower!
 

·
Registered
Joined
·
670 Posts
3:45 diff will have you revving around 3000 at 100kph so watch the diff change... don't go crazy! I have a c10 3 speed and 3:45's in my au v8
 

·
Registered
Joined
·
378 Posts
Discussion Starter #15 (Edited)
I question how much weight is a lil bit? When i used to misbehave with my mates in melb. We'd argue about who gets to carry the extra passenger when we went out!!! 50kgs can make a difference. At one stage during our mod stages between his car and mine the dif between victory and loss in a friendly fling of throttle happiness was who had the extra passenger or even who had the (no racist comment) light asian mate onboard (about 55kgs) and who had the euro mate on board (approx 100kgs)
I agree on that so much as well, even 30KGs makes that little bit of difference, especially when first accelerating. My XF beats a VN on a rolling start, if we are doing 80km + and then both accelerate we stay level. Its just the start when the VN takes off....

In answering that, the XF sedans kerb weight is 1333kg the VN sedan is 1311kg so 22 kg isn't much lighter, but could still equate to .03-.05 of a second faster, especially during take off.

Why no change stall? I think the diff gears will make a big difference, the cam is a good idea to move power up the band as is exhaust and extractors. Be carefull not to mess up the exhaust as when i first fitted the 2 1/2 system to my el it went slower!
You can change stall con? How did you manage to mess up the exhuast and end up going slower! Did you have extractors with this exhaust, or just a 2.5" exhaust on its own...would be interesting to know how you lost the power? Extractors are only for high end speed anyway....when you hit a bout 70km +.....

3:45 diff will have you revving around 3000 at 100kph so watch the diff change... don't go crazy! I have a c10 3 speed and 3:45's in my au v8
Can changing the the diff gear ration damage/affect my engine seriously, because the engine is going to rev higher, the XF 4.1 litre isnt made to rev higher......

Thanks.
 

·
now with EF power!
Joined
·
891 Posts
It wont rev any higher. It will just run through the gears quicker.
 

·
Registered
Joined
·
378 Posts
Discussion Starter #17
It wont rev any higher. It will just run through the gears quicker.
I thought in order to do this it needs to rev higher, faster....? And thats what a new diff gear change does.....
 

·
Registered
Joined
·
670 Posts
Yes it will rev quicker and help your take off! None of the 4ltr fords are safe past 5500-6000rpm. They not happy rev engines. All i'm saying is watch the cruise rpms so as to keep your car pleasurable to drive the way you drive it. Lots a highway travel and shorter gears is not a good combo. You may find it'll rev a couple a hundred rpm before gears change due to auto not keeping up as well but it's not a drama.

Why not change the stall, if you change cam it may be a consideration.

Your engine is a pump! when i upped the exhaust my power went down because it was too big for a stock engine (slow air speed). I added extractors and it got a lil better, added chip, cam and shorter (4:11) gears and ended up with a nice quick n/a el six with 144rwkw. Then i added a vortec and wow it was great. Got bored and wanted the V8 rumble. Now i have a eight with only 137rwkw but the comp and cam will change all that.
 

·
Registered
Joined
·
42 Posts
There are a number of reasons why the VN V6's were quick. They were light for their size. I'm fairly sure they were lighter than XF's and were a lot lighter than EA's. VN's had a very low 1st gear in the 4 speed auto and the V6 has very strong torque at low rev's. When the VN's were new a manual to get 100 in the high 7's and the auto's in the low 8's. These were the very first of the series released around September 88. Later models lost performance.
 

·
{';'}
Joined
·
4,345 Posts
I've also wondered the same question for a long time :)

I was wondering whether someone could answer a hypothetical question for me... If the XF/EA/EBII/ED had the same gear box and diff ratio as a VN, which would be quicker then? My next plan on improving performance figures for my auto ED is to drop in 3.7s/3.9s. I'm not so concerned about highway driving but I do want to take this into consideration. Would going from 3.08/3.27 diff ratio to 3.7/3.9 diff ratio change my 0-100km/h times by much?

Thanks fellas (good luck beating those damn VNs!).
 
1 - 20 of 51 Posts
Top