The 2.2 torqe dip

Lightning_Coupe

I'm sure all of you have felt the hesitation of the z22se between 2500 and 3500 rpm before it really starts to pull. Well having had my car on the rollers about three times now over the past couple of years, along with several other 2.2 owners its aparent that its a charicteristic of the engine and is shown in the torque curve pictured bellow.

Theres nothing wrong with my engine, you really can overlay this curve with any other 2.2's rolloing road results and they will have the same dip. Ive even seen the graph of a 2.2 with every debias acssesory feasable fitted, including inlet and exhaust manifold, cams, sports cat and remap, and it had the same dip in torqe. Not quite as bad but it was still there!

So what is it? what can we do to make it a nice smooth progressive torque curve? The around town pull of the engine would be superb if we could get rid of that dip!

So if you have a rolling road graph, get it posted for comparison, and more importantly, If you have managed to smooth the bugger out please share with us what modifications you made to achive it!

Andy_Coupe

Yet to get mine on the rollers but ive felt the dip! Has i nice pull around 2500 rpm but the one at 4000 rpm is better 😃

JohnnyN

Here's my 2 recent power graphs. The first from Courtenays and the second from A.P. Motors a week later. I've had the pre-cat removed, 200 cell per-inch sport cat fitted, remap, airbox mods and a modified cylinder head. (The Courtenay graph shows before mods and after mods power)

I must say, that the opening torque graph at the top of this thread is pretty impressive at 186lbs/ft. :shock:

What have you had done to yours??

Brother_Leo

Well Johnny as you know mines standard and the wife sez its got to stay that way or else :cry:

JohnnyN

Or else it is then!!

rofl..

Brother_Leo

JohnnyN said:
Or else it is then!!

rofl..

Erm -- well ok, when i get home tonight she is gonna be told that the car is going down to Norfolk for its holidays and should come back rejuvinated :wink:

JohnnyN

Brother Leo said:

JohnnyN said:
Or else it is then!!

rofl..

Erm -- well ok, when i get home tonight she is gonna be told that the car is going down to Norfolk for its holidays and should come back rejuvinated :wink:

Thats the stuff. Looks like TurboDave has taught you well young Jedi.

😃

Lightning_Coupe

Your graph shows the same dip in torque, Ok it dosent look as agresive as mine but thats becouse the scales are different, its only about 10 ft/lb on both graphs but its still there. what head work did you have done? Did you get cams? I wonder if its the profile? whilst youve obviously achived a good gain the two lines look strangely similar.

As for my 180 odd ft/lb of torque, I'd take it with a pinch of salt. I dont know how reliable those rollers are? Ive had varying figures from all over the place, I dont think rolling roads can ever be truelly trusted. There more of a tool to gauge change imo.

JohnnyN

Lightning CoupÃ© said:
Your graph shows the same dip in torque, Ok it dosent look as agresive as mine but thats becouse the scales are different, its only about 10 ft/lb on both graphs but its still there. what head work did you have done? Did you get cams? I wonder if its the profile? whilst youve obviously achived a good gain the two lines look strangely similar.

As for my 180 odd ft/lb of torque, I'd take it with a pinch of salt. I dont know how reliable those rollers are? Ive had varying figures from all over the place, I dont think rolling roads can ever be truelly trusted. There more of a tool to gauge change imo.

I was advised to hold on the cams for now as Courtenays have some new cams in developement. If the wife allows it, I may be going back later in the year for a replacement high-flow pre-cat pipe replacement and if the cams are available I might have them done too.

BTW, i've said it before on VXLSCC, your car looks stunning mate.

Lightning_Coupe

Thanks Johnny, your motor looks bloody great too! Ive got a soft spot for veccys since my neighbour had a GSi.

Thanks for the info on your tunning, Ill have to keep my ears pricked for any development on those cams and weather they improve the torque curve, but Id be more than happy with the gains youve achived. I quite fancy a lightweight flywheel to be honest, Ive heard great things about them, you should consider that aswell if you take another trip to northfolk. :wink:

ando

Yes lighting i remember the RR.Mine was vitually the same in the dip.If only we could sort it all out i will put mine on so you can see notsure.gif

OOH yes flywheel and throtte body yes pleeeaaasseee !!!! 😃

Few things to sort out first still saving thaugh !!!

Just a question the vx 220 not vxr the 2.2 does it have more hp am i correct ??? if so could we get hold of a graph for that and see what difference is interms of the dip and if anythings OE ??

phil-h

3.7k revs is the sweet spot for me. Accelleration is rocket powered 😃