Tuning my DR750s on Chrome

[Greg E]

Even the old motor made ~50 psi at 2500 on 10w40. I can run 20w50 to get the best pressure possible. I wasn't there to see any logs or anything, but if you have the load at that rpm you could go from thinking it is going to run like 10-12 degrees of timing and actually run 20+

not great for anything. I can't quite wrap my head around how the fueling using the arc2 can work if the maf signal is that hosed, but I am sure there is an explanation.

I keep asking Todd to give me the ARC so I can play with it on my car and figure that out. There was only one car I remember tuning with the arc and actually logging engine load and that was one of my old DR500 stealths. It saw 110load in the peak ranges. I had 660s in that car.

[AdamVR4]

Any validity to a simple static load analysis on the conrod in these low oil pressure, high torque scenarios? Perhaps there really is enough torque to overwhelm the pressurized oil layer. What's the oil pressure at the conrod bearing at 25 psi gauge pressure?

[Greg E]

Towing my car to the track with a 7.3 F350 I see 60psi at 2200rpm with 1200F EGT.

At 2200rpm in my GT on Platinum Ultra I see about 40psi.

It's an intriguing theory for sure but I'm not seeing much evidence to support it. Definitely gonna keep an eye out for it though.

[Chris@Rvengeperformance]

I guess no one really knows, but I wish I knew it was safe to run these 750s on the 3.5 with e85 and not tear the bearings up.

I mean if I have to pull so much timing or boost at low rpm to keep it together I might as well run the 16Gs.

[R/T93]

Towing my car to the track with a 7.3 F350 I see 60psi at 2200rpm with 1200F EGT.

At 2200rpm in my GT on Platinum Ultra I see about 40psi.

Hmm at 2200 I am at 70 psi in my 3000(4.2 bar). 137k original motor/pump... I would venture to say any new build would have pressure similar to mine. 40@ 2200.... would freak me the f out.

From the phone.

[J. Fast]

Hmm at 2200 I am at 70 psi in my 3000(4.2 bar). 137k original motor/pump... I would venture to say any new build would have pressure similar to mine. 40@ 2200.... would freak me the f out.

From the phone.

I would be pleasantly surprised if you have 70psi of operating temp oil pressure at 2200rpms seeing how the manual spec's 12psi at a 900rpm warm curb idle. If you're gaining 50psi of oil pressure every 1500 rpms you'd blow the springs out of the oil pump. That means you'd have 260psi of oil pressure at redline. If you hit the clutch and take your foot off the pedal the pressure would drop to 12psi curb idle immediately. Man that sounds like a recipe for a wadded up engine.

FYI Nelson Bernarde wraps his racecar engine out to 11,000 rpm's and his peak oil pressure is roughly 140psi.

There was this thread on 3si about 3 years ago where a guy from a shop in England was modifying stock oil pump housings and fitting a high volume/high pressure system that netted an increase of the base oil pressure by 10psi at curb idle and 15% linear across the board. I believe he works for a NASCAR team now building 1000hp engines. His specialty was oil systems. He said that modest gain was enough to prevent spun bearings in our traditional oil starving engines.

[R/T93]

Sent PM to avoid OT discussion.

From the phone.

[Chris@Rvengeperformance]

750s came back in today. still not sure about running them.

[NOMIEZVR4]

750s came back in today. still not sure about running them.

and the plot thickens....

[anyonebutme]

750s came back in today. still not sure about running them.

dont run them, send them to me, save yourself.