Down on standard power with chip and smaller pulley!

[mondy 0]

Hi,

 

I've recently had a brand new supercharger because the belt snapped on my old one causing a big hole in the top of it! Anyway at the same as the new charger I got a chip and smaller pulley (68mm) for it. I thought it was pretty quick but I took it on a rolling road and I'm not impressed with the graph (attached).

 

As you can see it loses power after 5000rpm. It's also way down on power - they quote 152bhp at the fly which I know means nothing but the wheel figure is only 115bhp - I was expecting more like 140-150 - am I just being over optimistic there? Also, the torque doesn't seem high enough to me either - I thought with the mods I have it should be at least 170-180.

 

Has anyone any ideas what might be causing this loss of power? The bloke on the rolling road said it was because I have the boost return mod and it's causing it not to run right but I can't see any reason why that would cause it - I'm thinking it might be a boost leak somewhere but I've had a quick look and can't see anything obvious - any other things I should be checking?

 

Cheers,

David.

[dr_mat 0]

I'd expect to see around 135bhp at the wheels for a completely standard G60, so yours is clearly unhappy.

I've never heard of boost return being a cause for such poor power outputs though. I suspect there's a problem with fuelling - maybe your pump simply can't supply enough fuel above 5k rpm. If the torque graph was to carry on with that healthy 160 lbft torque you'd easily clear 175bhp on that power curve, so I would start with fuelling..

[funky 0]

i had a very similar output with the cam timing one tooth out

hth

funk

[Supercharged 2]

Yeah, check Timing then check the throttle is opening fully!

[mondy 0]

dr_mat - is there a way of checking the fuel pressure - I know some cars have a valve that you can fasten a gauge to to check it

 

I'm pretty sure it isn't one tooth out because I had it rolling roaded at the same place before the charger went and it produced about the same figures (slightly higher actually) and that was on standard pulley and no chip!

 

If the throttle wasn't opening properley then would that mean it wouldn't rev as high?

 

One other thing I forgot to mention is I did the test on the MFA last night and it produced 1700 which is well down on what it should be according to the guide on here hence why I'm thinking it's a boost leak.

 

Thanks for the replies!!

[steveo29 0]

was it a new vag charger?? 2nd hand or what?

[W3RKD 0]

dr_mat - is there a way of checking the fuel pressure - I know some cars have a valve that you can fasten a gauge to to check it

 

I'm pretty sure it isn't one tooth out because I had it rolling roaded at the same place before the charger went and it produced about the same figures (slightly higher actually) and that was on standard pulley and no chip!

 

If the throttle wasn't opening properley then would that mean it wouldn't rev as high?

 

One other thing I forgot to mention is I did the test on the MFA last night and it produced 1700 which is well down on what it should be according to the guide on here hence why I'm thinking it's a boost leak.

 

Thanks for the replies!!

 

hello there, also worth checking is the pastic outlet box on the charger as these are VERY prone to leaking..

[stevemac 0]

mondy, Boost return re-route is definitely not your problem. :wink:

 

1. Exactly what type of chip are you now using ?

2. Was a shorter alternator/charger belt fitted at the same time as your smaller pulley ?

3. How old & exactly what spark plugs are you using ?

4. Has your "carbon can" been removed ?

5. Where did you get the charger from ?

6. Did you run it in properly ?

7. Is there any oil on the outside of the charger casing ?

 

MFA boost check is not the most accurate way of checking how much boost you have - did you also perform the MFA boost check before your old charger blew (so as to gain a comparison) ?

[h100vw 0]

Could it be the not so famous distributor fault? I had a flat spot like this on my Golf. It did produce 178hp before the dip in power.

Gavin

[mondy 0]

Hello again

 

All parts are from g-werks so there shouldn't be any problems there.

 

I ran the charger in for about 350 miles and haven't given it a lot of abuse yet.

 

I put new plugs in around january this year and have done less than 5000 miles since then. I haven't removed the carbon can.

 

I've checked the fuel pressure and it stays just over 3.5bar all the way to the redline - I've also checked the flow rate and it did 600ml in about 15secs which I think is OK.

 

I've decided that I'm going to take it to another rolling road tommorrow just to make sure that there is actually a problem before I look at anything else!

 

Thanks again for all your suggestions they're much appreciated!

[W3RKD 0]

have you checked the timing ?

[mondy 0]

Right I've checked the timing eventually and at 2000rpm it's at 9deg and it advances through to about 54deg as you rev it higher so that seems OK.

 

I'm beginning to wonder if anything is wrong so I took it to another place just for a quick power run and they said it had 142bhp at the wheels - from what people say the first place hasn't got the best reputation so I'm not going to read too much into the first graph!

 

Anyone got a rough idea of what power I should be expecting from the above mods (68mm pulley, chip and new supercharger)?

 

Cheers,

David.

[dr_mat 0]

Does it *feel* like the engine drops off at high revs? You'd easily notice if there was a drop such as you're seeing in the first graph. 142bhp @ wheels is a good figure, and is close to matching the output of most average VRs on the road...

[mondy 0]

It doesn't feel like it drops off but when someone shows you a graph of the power dropping off it kinda makes you think it must do and you just haven't noticed - however, after checking most things and having someone else drive it I reckon there isn't anything wrong with it after all.

 

I'm not going to say what I think of the first rolling road place (Geoff Bloor in Nottingham) except that I will NEVER be going there again and will recommend other people never go there either!

 

Once again thanks for all the replies they've kept me busy for a while!

[dr_mat 0]

Forget the power plot, you can't *feel* power, you *feel* torque. That's the force that's applied to the car, and that's what propels it. power is secondary.

If the torque was genuinely dropping by 30-40 lbft above 5000 rpm then you'd know about it, big style.

[stevemac 0]

Right I've checked the timing eventually and at 2000rpm it's at 9deg and it advances through to about 54deg as you rev it higher so that seems OK.

Doesn't sound very OK to me. :shock:

 

Timing should be set at 2500rpm and should be 6 degrees BTDC (+/- 1 degree)

 

Current chain of events - engine will try to "pink" (due to the advanced timing), ECU will automatically retard your timing, thus limiting your power.

 

G60 Timing Proceedure:-

1. start engine

2. disconnect blue temp sender

3. keep engine revs at 2500rpm (may need a friend)

4. set timing to 6 degrees BTDC

5. run engine at 2500rpm to re-check the timing is correct

6. re-connect blue temp sender

7. set c/o to correct percentage

8. go for a blast up the road 8)

[mondy 0]

When we checked the timing higher in the rev range it retarded loads with the blue sensor disconnected but once it was connected back up the timing *seemed* ok - does you mean that it shouldn't have been retarding with the blue sensor unplugged?

 

Also, I'm not sure how you set the CO because the lambda sensor brings it to .50 no matter what you adjust - I was told to set the CO pot to 600ohms which I've done.

 

Cheers,

David.

[dr_mat 0]

I suspect it's fine. The first graph was cocked up. Ignore it. Your second run showing 143bhp @ wheels indicates that you're pushing at least 170bhp at the crank. Which is totally healthy!

Worry about more important things! Living with Corrados means there's *always* something else you can worry about! :)

[stevemac 0]

When we checked the timing higher in the rev range it retarded loads with the blue sensor disconnected but once it was connected back up the timing *seemed* ok - does you mean that it shouldn't have been retarding with the blue sensor unplugged?

With the blue temp sensor disconnected - the engine will neither retard nor advance the ignition timing. The ECU corrective timing system is completely disabled. What you will find is that the ECU will not advance the timing unless this sensor is connected.

 

Re-set your timing - following the above proceedure & I suspect that your problems will be solved. :wink:

[mondy 0]

OK I'll reset it and see if it makes a difference - cheers for the help! I'll let you know if it seems to have made a difference.

 

dr_mat - So far I've been pretty lucky with my car - until the s/charger blew itself to bits! I hope it's not a taste of things to come!

[W3RKD 0]

timing can be set with blue cts sender off and rpm anywhere between 2K-2500k , so mondy sounds like your timing is fine to me if you have set it at 2k.