Well I went to the Dyno this morning to see how much power I am making now that I upped the boost. The results were.
I watched my fuel pressure gauge closely throughout the pulls and ascertained that my wastegate was blowing off at that rpm. I could watch the fuel pressure climb continually until it just dropped at about that rpm.
Due to the fact that UPS has apparently fallen in love with my boost gauge and decided to keep it I didn't know how much pressure I am making. We plugged a gauge into it on the 3rd and last pull just because the dyno guy was really confused.
It goes like this. Boost climbed really hard until it reached 14 psi at which point the wastegate opened and dropped it to 9 psi for the rest of the pull. Watching the fuel pressure and boost simultaneously they had the same reaction at the same time.
The AFRs' were pretty good this time overall seeming to go slightly lean just before the wastegate opened. I probably need to adjust the FMU to start opening a little earlier now. And perhaps even allow a bit more rise as boost increases. Completely different from the 7 psi scenario. (just as Todd and Sweeney said it would be)
Yes, when my headgasket blew last summer I switched to the B35 head due to the better ports and bigger valves. I knew I was destined for a turbo so I also upgraded the headgasket, put in ARP studs and put a UUC clutch in at that time.
It was kind of sluggish NA when off cam but felt as strong as a stock B34 when on cam despite the lower compression ratio.
Another interesting and scary thing that was noticed today. The engine fan, at high RPM' was flexing out so far it was contacting the radiator around the edges of the fan blades. The radiator has the circular scars from this. Anyone else have this happen?
GregATL wrote:Another interesting and scary thing that was noticed today. The engine fan, at high RPM' was flexing out so far it was contacting the radiator around the edges of the fan blades. The radiator has the circular scars from this. Anyone else have this happen?
Yes, and in my case it was caused by bad motor/transmission mounts.
GregATL wrote:Another interesting and scary thing that was noticed today. The engine fan, at high RPM' was flexing out so far it was contacting the radiator around the edges of the fan blades. The radiator has the circular scars from this. Anyone else have this happen?
Yes, and in my case it was caused by bad motor/transmission mounts.
Jeremy
Hmmm. Why would bad mounts cause the fan to flex more?
Kidding. What you're saying is that bad mounts put the motor forward in the chassis enough that the fan didn't have the necessary clearance to the radiator. What is the correct amount of clearance between the fan and radiator? That's got to be a tough question to answer.
It is a tough question to answer, but irrelevant really. The "bad stuff" was happening to me under load as well. The mounts just weren't holding things where they should have. At idle/rest everything looked peachy, so I was really kinda scratching my head as to what the problem might be. It's not something you'll be able to measure and quantify.
Somebody on the old board suggested replacing the motor/transmission mounts when I described the problem, I did because I couldn't find anything else to blame, and the problem was solved. I seem to remember checking fan clutch and and water pump axial play being being suggested to me as well at the time (the assembly shouldn't wiggle), but I had neither.
Another interesting and scary thing that was noticed today. The engine fan, at high RPM' was flexing out so far it was contacting the radiator around the edges of the fan blades. The radiator has the circular scars from this. Anyone else have this happen?
Mine went one further on the M5 recently. The fan spit off a couple of blades and one went into the hood hard enough to cut the under hood insulation, bend the sheet metal and crack the paint.
So far I've replaced the water pump (big axial play but not leaking) the fan clutch and of course the fan. I'm adding the engine and transmission mounts to my list of parts to order.
Yea, I replaced the fan twice on mine before I got it figured out. The first time I thought it was just age, then it chewed up another one in short order.
