Hi, I bought the 740 after it had been off road since 2004. Now MOT'd and useable I recently compression tested the B230ET engine to get readings around 125psi. This seems low to me and my question is can anyone tell me what the correct reading should be, 160?180?200? Thanks a lot for your help
What is the mileage on the car? Any history with it? Did you test with the engine warm or cold? Compression ratio on the B230ET should be 9:1 so should be at least 132psi (simply multiplying atmosphere pressure 14.7 by 9, but does not take into account the increased pressure caused by the heating of the air in the cylinder). Unless your engine has had some modifications that lower the compression ratio. If the pressure is consistent across the cylinders that would normally be ok. Is there an issue with the engine running?
camshafts with overlap can give a lower reading, Dave
Thanks very much for your comments. Mileage is 167k and no history other than old mot. Belts, filters, clutch all Volvo stamped so would think it's been looked after. Comp tested when hot. Engine runs fine and is a joy cruising on the motorway. Puff's a little blue smoke on gear change but all in all it's good. Local engine recon shop said psi should be around 200 hence my post and Haynes claim 9-11 bar. Thanks a lot.
Just deliberating whether to have it rebored to restore the missing BHP.
put it on a dyno and see what it is making, when you did the compression test did you have the throttle wide open ? Dave
First time I tested yes but second time I must admit no, however the readings were very similar but I'll check it again later today dry and wet and post results. Of course Dyno wouldl give an accurate reading. Thanks
Hi, Cylinder. Dry. Wet 1. 122. 133 2. 128. 140 3. 121. 135 4. 129. 144 Tested hot, fuel fuse out, coil disconnected, and throttle fully open. Obviously rings are worn but it's booked in for a Dyno on Monday so will see what that reveals. Question for the panel, in your opinion is the B230ET worth the work/money to restore full power? Thanks for your patience, help and pointers. Pete
Hi, Cylinder. Dry. Wet 1. 122. 133 2. 128. 140 3. 121. 135 4. 129. 144 Tested hot, fuel fuse out, coil disconnected, and throttle fully open. Obviously rings are worn but it's booked in for a Dyno on Monday so will see what that reveals. Question for the panel, in your opinion is the B230ET worth the work/money to restore full power? Thanks for your patience, help and pointers. Pete
I'd be tempted to just fire some boost into it and enjoy it. If I breaks then fix it!
Thanks but can you explain fire some boost I've played with the airflow meter and the increase in fuel has smoothed the tickover but I'm uncertain as to how far it can go. Thanks Pete
Increase the turbo boost pressure, standard is 6-7psi so up it to 10-12psi. It will make a huge difference.
I think you can simply fit a Manual Boost Controller which overrides the standard boost setting on beast, which is set by the diaphragm device on the turbo. Dead simple to fit, BUT - get an accurate boost gauge to set it up with at least. Saw this done on a 940 recently and it went up to 15psi quite rapidly, which you wouldnt know about using only the standard boost gauge on the dash. You may find that a chemical clean will release the crud round teh rings a little and help them to seal - it will clean the injectors too for smoother running, then an oil additive to help the valve stem seals to soften a little - all things that will help restore compression and oil sealing A LITTLE if its been stood a while. Sometimes, as well, they just need to be "run in " again gently to get used to a different driving style after being stood around, or used for just "pottering about" . Keep in touch with progress and the RR results . Cheers, Woz
Cheers woz and good info. I have put an engine flush through it and fresh oil in Jan came out like treacle. When I can figure it out I'll put some pics on.
Have a read here about the spec and what you can and what not to?.......http://forums.turbobricks.com/showthread.php?t=171576 I had the `89 model and when fitting the MBC to around 14/15psi it does go well but so does the petrol....17/18mpg whatever you do?
Thanks a lot,
Just back from the Dyno with a reading of 146BHP and a suggestion to recon the turbo due to the smoke on overrun.
It's got more go in it after the thrashing on the rollers and I may refurb the turbo later in the year.
Thanks for all your help and advice.
Pics later.
Pete
Is it engine out to put new rings in or can it be done in situ? Thanks Pete
[QUOTE=Potato pete;816915]Is it engine out to put new rings in or can it be done in situ? Thanks Pete[/QUOTE] I'd say engine out, as getting the sump off in situ will probably be impossible.
Cheers Dave