Z3 2.8 Rolling Road

[Sam]

Hi,

I took my 1997 Z3 2.8 to a rolling road yesterday and achieved 165.2Bhp@5045rpm and 178.3Ibft@4080rpm at the flywheel. The car is totally unmodified apart from a standard replacement cat and exhaust (They are not genuine parts).

This is lower than the 190Bhp and 210Ibft of torque that I believe it should be. The car has done 73,000 miles and drives very well.

The guys at the rolling road said this is normal and BMW's of this age are all about 20hp less than they should be, a friends 3.0 Z4 achieved 211bhp ( around 20bhp down) and a 540i did 264bhp (again around 20bhp down). The newer M135i cars we had also there at the rolling road both made the 320bhp they should along with a Fiat 500 Abarth also making its magic numbers so I believe the rolling road is accurate and the guys there are very knowledgeable etc so can rule that out.

So I just wonder if the engine could make 190bhp and I should be looking for worn out parts, get the fuel injectors cleaned and rebuilt along with looking at the ignition system etc or do I have a healthy engine as it is?

If anyone has any information/help on this it would be much appreciated.

I have attached the printout of the rolling road graph.

Sam

 

[Jack Ratt]

73K miles isn't a lot so could it be that it needs a good run out. A few blasts up and down the A30 might sort it. As you say, cleaning the injectors and fuel lines wont hurt either

 

[andyglym]

Do you use RON 97 fuel? A tank of that and a good stretch of her legs should help.

 

[Grumps]

Welcome Sam and welcome from Mansfield. An intresting right up thanks. I have a 2.8 also. I've always unstood that engines will loose some bhp as they get older and more worn. If you decide to try and get the missing horses back please let us know what you've done and if your successful.
Cheers
Dave

 

[Sam]

Shell V-power Nitro is what I have in the tank, it is a weekend car so when it goes out I thrash it so I think I will start with a compression test!

 

[andyglym]

Shell V-power Nitro is what I have in the tank, it is a weekend car so when it goes out I thrash it so I think I will start with a compression test!

Hmmmmm, mines a 2.8 too, no idea how many horses may haves escaped over the years. I'll stick a rolling road in the list of things to do in the near ish future. Be interesting to hear what you come back with.

 

[Brian H]

Welcome @Sam, interesting first post, 25bhp loss for an 18 year old car is not too bad IMO (just over 1bhp per year). Although you have the suggested figures by BMW for a new car, these could have been a little optimistic to start with, I.e. figures are obtained in ideal test conditions.

If the car is a weekend car and it is running well, I would not try and chase the figures too much, you could throw money at a problem that does not really exist.

 

[t-tony]

Agree Brian, you can take the original manufacturers figures with a pinch of salt. If you say half the difference is more likely to be nearer the mark and at the age of your car I would be happy. Enjoy what you have, don't worry about what you don't.

Tony

 

[oldcarman]

I totally agree that you are likely chasing about 10hp due to wear and 10hp of ghost power that the mfger. Built into their advertised hp. If you could get ahold of a brand new car and run the test it's highly unlikely any, no matter what make, with the top expensive models as possible exceptions find the results matched the advertised rate. You may gain some Hp back with a total blueprint rebuild but would you notice the gain in the seat of your pants, I doubt it!! Except that your wallet would be empty so sitting on it would be more comfy. Drive it, enjoy it and flog it!! JIM

 

[Sam]

Thanks for the comments, I think an injector clean and rebuild will be worth the cost, £12.50 per injector, hopefully they are not flowing correctly and I will get my horses back!

I believe as the car is OBD1 I cannot remap the ecu? It needs to be done the old school way, take the ecu apart and replace the chip? Has anybody done this etc? I would like to get near the factory bhp if possible before carrying out any performance tuning. I need to look at my ebay exhaust parts and see if a restriction could be holding it back. The cat is much smaller than the original BMW part.

The E36 328i is a popular car to tune for drifting etc so I might find information on one of those sites, they all seem to claim in excess of 210bhp with modifications. I am keen to swap the inlet manifold for a M50 variant and try and reclaim the loss in torque with a chipped ecu and lightweight crank pulleys etc. I will get it back on the rolling road after each step to see what the effect is.

I have a track day booked for the 1st of August so will be focusing free time on replacing all the tired suspension bushes for the strong flex red variants. I also have a pair of e46 330i front brake calipers and carriers which looks to be a cheap upgrade, however I have seen some recommendations that the e36 M3 brake servo and master cylinder is required in order to prevent excessive brake pedal travel. Has anyone tried this on a Z3?

Thanks.

 

[Kit]

Hi @Sam how much do they charge for this service.
Might drive mine over there.

 

[Sam]

Not a lot £30-35. Well worth it.

 

[oldcarman]

Now you're into a totally different role than I thought your first thread was going. For advice on drifting, etc you need to contact @Tommy Bates for his input. He's built himself a pretty nice z3 drift car. You can check his posts under Tommy's drift car. JIM

 

[Sam]

Hi Oldcarman, the car isn't for drifting, the idea of looking to the drifting sites was that the e36 328i are very popular and so get tuned, it was the engine tuning advice I would be seeking.

 

[oldcarman]

Hi yes I realize that but Tommy has a lot of experience and is right here at your finger tips!! But I still doubt that you'll get to the original 190hp in stock form as it was a fictitious number to begin with. You need to know what your end use is going to be so you don't throw money into parts that aren't really going to get you there. It's one thing to have that 210hp number on paper and another to put it on the road. Good luck! JIM

 

[Brian H]

I have a track day booked for the 1st of August so will be focusing free time on replacing all the tired suspension bushes for the strong flex red variants. I also have a pair of e46 330i front brake calipers and carriers which looks to be a cheap upgrade, however I have seen some recommendations that the e36 M3 brake servo and master cylinder is required in order to prevent excessive brake pedal travel. Has anyone tried this on a Z3?

The E46 330i front brake calipers and carriers fit nicely and you get 325mm discs, they are bolt on options however the difference in caliper piston size will affect your pedal travel, its not too bad once you get used to it but it will put the brake pedal in line with, if not lower than the accelerator before it engages with the brakes, once it engages it is solid. The stock caliper piston size for the Z3 (apart from the ///M) is 54mm, the E46 330i is 57mm IIRC. As you stated you can change over your master cylinder to suit but getting a bolt on replacement can prove tricky, there is not a lot of free space when you take in to account the ACU box of tricks. Another thing to consider is your ASC? On my car (later type) I have DSC and need ports on the master cylinder to accommodate the DCS sensors, not sure about your car but worth a thought.

Our cars use ATE manufactured parts for the booster and master cylinder, The Z3M, E36 & E46 use a mixture of ATE, Girling and/or Lucas. The size of piston in your Master Cylinder is 20mm for the rear circuit and 23mm for the front circuit, you will need to look for something like a 20/25 to compensate for the bigger front caliper piston, there is a whole load of maths out there to properly calculate the size you need, it can be a little bit mind blowing TBH.

The only upgrade you can do without any hassle is to upgrade to the Z3 3.0i calipers, carriers and discs, this will increase your disc size from 286mm to 300mm and will work 100% with your master cylinder.

A bit of advise if you are tracking your car, get some cooling onto/into the front brakes they will thank you for it, upgrade your brake fluid to high temp fluid and get a decent set of pads, latterly I have been using EBC Blue stuff pads, superb bite and last quite well also. If you did these last few items on your stock brakes you will be surprised just how well they will stop the car! Maybe try this first before changing over a load of stuff.

Good luck with your track day, the cars are a hoot to drive.

 

[Lee]

Give the car a good service get it breathing better, then get her Terra cleaned. Let me know how many horses come back

 

[oldcarman]

Give the car a good service get it breathing better, then get her Terra cleaned. Let me know how many horses come back

What is a Terra cleaning @Lee? Not anything I've heard of here? JIM

 

[andyglym]

What is a Terra cleaning @Lee? Not anything I've heard of here? JIM

https://www.google.co.uk/url?sa=t&s...wQFjAA&usg=AFQjCNGgObsnj5gZtjLcVWnLfLENE5KDqw

As made famous by Ed China (Wheeler Dealers). A full on chemical and very high quality fuel system flush. Has some good reviews though not used it myself.

 

[Lee]

Had it done to my dads car. (Jaguar) and my mates 400 bhp 335D and its made so much difference. I have booked mine in later this month.

Lee