Auto loss
 

Hi all, just a quick query, how much power loss does an auto box generate over a manual gearbox?
I know they take a bit off, but last night, I was following my brother who has a zt cdti manual. His car is a standard 131hp, and mine is a 75 auto, with 160 remap, plus all usual cdti things sorted.
Now, I'd have expected that with a potential 30bhp increase, and the extra torque, I'd be able to at least keep right on his tail, and be able to overtake and pull away on a straight, however I found I had to work hard to stay with him, and he actually pulled away from me quite easily. I tried with the car in both normal and sport modes, but he still pulled away from me when accelerating.
Surely the auto box can't take away that much power and torque?

Auto boxes do lose a fair chunk compared to a manual... mainly down to the torque converter.
My best advice would be to change the oil in the autobox as oil ATF fluid does amplify the power loss.
If that doesnt help then im unsure, i'd be checking for any underlying issues...

In real terms 30hp when "racing" will make very little difference

Your best test is a rolling start... so say 30mph both in second (sport mode in auto box should put you in second at 30)
Then both accelrate away at the same time (as best you can) and see how different the cars are.
If you get left then there's clearly an issue, my personal opinion would be that a mapped auto would be on par and quicker top end then a stock 131 manual.

The small bit you lose due to the box should easily be made up during the gear changes :shrug:

Methinks you're CDTi needs checking...... :o

But.. over say 300 miles the manual gain is unlikely to be significant innit... :shrug:
...

We weren't racing as such, it was just at places such as junctions, he'd start to pull away from me even though I was accelerating fairly hard. To be fair, once we got upto around 60-70 I did slowly start to make up some ground, but I thought the extra torque would show lower down. I'll have to check the atf as that's about the only thing that's not been done since I've had it.
My car has been fully checked over by philt4 in the last few weeks and there were no issues found.
I'm not overly worried about it, it's got enough pull for general driving, I was just a little surprised at him pulling away from me when compared side by side.
Having said that, I guess there is every possible chance that his car could've had a remap in the past that he's not aware of!
Before I got a cdti, I used to hear from people saying how their remapped cdti would out accelerate a 190, but going on this basis, there's no way on this earth that my 75 would get anywhere near my old 190!!

Well i have done the same test with my brother and he used to pull away at an junction all the time untill i got in too 3rd gear then i would be gone.
But another one is change the oil in the autobox and i have had an new gear box ecu put in well second hand one and its now faster and me gear changes are so smooth now thank god
i might be wrong but mine now feels so nice when i put my foot down lol

having had a play with the missus in the CDTi when i had the v6 i can indeed vouch for a mapped cdti being only slower top end than a 190...

I'm guessing it wasn't an auto? Lol

My experience is that a duff MAF makes the car a bit breathless at higher speeds, at least on mine. With the remap and a duff maf, it would accelerate to motorways speeds then feel like a strong headwind was keeping the speed down.

Now not such issue. Also a clean EGR and manifold helps the car breathe much better, aiding responsiveness.

Also, try with the EGR vacuum line blocked at the EGR valve (if you still have it). The difference in responsiveness was marked in my auto diesel. Don't just disconnect as this is the same line used for the brake servo. :}

Lastly, try using D3 to hold onto gears, then change to D4 when ready, then finally put in D. The car will accelerate more cleanly as it is not trying to change up and you are control.

Thanks for all that, the maf is good according to Phil's t4. I recently cleaned the egr, and disabled it by blocking the pipe. I also did pcv filter, and intercooler o rings. Apart from the atf, the car is fully serviced and working as it should.
I do like the way the car drives, and when its on its own, it does seem to pull quite well, certainly better than before the remap, but like I said, I was just a little surprised at how much power the auto box loses, when compared with a standard power, manual version.