I would agree. Unless there is something really wrong, then an engine with lower-than-normal compression numbers should not be significantly more prone to a catastrophic failure than one with high numbers, it will just have a lower VE.
I do also agree with the sentiment about doing it right the first time. The problem is that things are not always equal. If it is me that is tuning the engine, then I am just as likely to do something stupid on an old crappy motor than a new shiny expensive one. The consequences are obvious. BUT, I am less likely to blow up the new shiny expensive engine after I learned on the old one. So I guess it depends on your goals, I consider my current stock motor somewhat disposable, and my long term goals are to have a shiny new one installed. Some boost on a marginal motor beats no boost on a marginal motorJ Marek From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bill Cardell Sent: Tuesday, June 10, 2008 11:23 AM To: [EMAIL PROTECTED]; miatapower List Subject: RE: turbo a motor with less than perfect compression? We get customers asking the question "I have a high mileage (140k up) engine, should I rebuild first or just turbo?" I usually recommend just running as-is, if it's healthy it'll still go another 100k if not drastically abused. Bill Cardell TurboDog's Dad www.flyinmiata.com www.fmwestfield.com Sales 1-800-359-6957 Tech 970-464-5600 Before you call, check out http://www.flyinmiata.com/FAQ/ Come to our Open House! August 14-17 _____ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bryan Wyatt Sent: Tuesday, June 10, 2008 12:21 PM To: miatapower List Subject: RE: turbo a motor with less than perfect compression? I should add that if the engine actually is healthy, boost away. What I didn't get is the advice--which I assume was Coop's--that, "hey you've got a crappy motor--boost it now and rebuild later!" If the motor's not crappy as Bill is pointing out, then it all makes more sense. -Bryan --- On Tue, 6/10/08, Bill Cardell <[EMAIL PROTECTED]> wrote: From: Bill Cardell <[EMAIL PROTECTED]> Subject: RE: turbo a motor with less than perfect compression? To: "Dillon" <[EMAIL PROTECTED]>, [EMAIL PROTECTED] Cc: "miatapower List" <[email protected]> Date: Tuesday, June 10, 2008, 2:17 PM I guess my thought is those are awfully bad numbers for an engine that is running well and not burning oil. If the car idles smoothly and pulls good vacuum, I'm not buying those leakdown numbers. It doesn't add up. Unless I misunderstood and it actually runs like crap. Not saying anything against Coop, maybe carbon dropped in from taking the plugs out or something. Bill Cardell TurboDog's Dad www.flyinmiata.com www.fmwestfield.com Sales 1-800-359-6957 Tech 970-464-5600 Before you call, check out http://www.flyinmiata.com/FAQ/ Come to our Open House! August 14-17 _____ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dillon Sent: Tuesday, June 10, 2008 12:02 PM To: [EMAIL PROTECTED] Cc: miatapower List Subject: Re: turbo a motor with less than perfect compression? I'm not the sort to worry. Why rebuild now when I can rebuild later? (serious - that is the question I'm looking to answer) - Dillon On Tue, Jun 10, 2008 at 10:56 AM, Bryan Wyatt <[EMAIL PROTECTED]> wrote: Correct me if I'm wrong, but I still don't understand the idea of running more air through an engine that is showing signs of weakness. It still seems like if you're that concerned about the engine (and the possibility of a rebuild) that you should spend the money to get a darn near perfect running engine, *then* spend more money to boost it. Your power level would be higher and you'd be happier because you're not sitting around worrying about the thing blowing up on you. -Bryan --- On Tue, 6/10/08, Dillon <[EMAIL PROTECTED]> wrote: From: Dillon <[EMAIL PROTECTED]> Subject: Re: turbo a motor with less than perfect compression? To: "Bill Cardell" <[EMAIL PROTECTED]> Cc: "miatapower List" <[email protected]> Date: Tuesday, June 10, 2008, 1:50 PM Hi guys, Thanks for all the input. I can't answer the detailed questions too definitively. I moved into a smaller apartment last year and don't have access to the tools myself (incredibly frustrating). Coop (of Coop's Miata) near Seattle did the tests while he had my car for a roll-bar install. I witnessed the compression test but not the leakdown test. As for how much oil, it wasn't too much as I recall, maybe a few teaspoons per cylinder? As for the leakdown test, I can't say for sure if the motor was hot or cold. I could ask but I doubt Coop would remember my specific car since this was a few months ago. I would assume it was hot, as that seems to be the thing to do, and Coop is experienced at these things. He said he could hear the air whistling and that it was definitely rings, but I don't recall if he said he heard the air at the exhaust, or the crankcase. I am assuming the crankcase. Does any of this add up? On Tue, Jun 10, 2008 at 6:59 AM, Bill Cardell <[EMAIL PROTECTED]> wrote: I'm with Tim. Make sure the engine is warm. Something else I've seen is dislodged carbon from the plug threads throwing off comp tests. On a good hot engine, redo both tests. Also, how much oil did you put in? Too much and you're just reducing chamber volume, which will push numbers way up. Also, as Tim said, where is the air leaking from on the leakdown? That is the utility of the leakdown test, it tells you "what" is bad. The bad thing is that no test I'm aware of will tell you anything about oil ring condition, but you say you're not using oil. _______________________________________________ Miatapower mailing list [email protected] http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower _______________________________________________ Miatapower mailing list [email protected] http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower
_______________________________________________ Miatapower mailing list [email protected] http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower
