Roush 402R oil pressure & temp
 

Just purchased a 2007 Cobra Roadster MK III with a Roush 402R-311 engine. Previous owner had no dyno pull or specs from Roush. Would someone with a similar engine provide a recommended minimum & maximum oil temp & pressure, & water temp? Thanks!

For street use I like to see no higher then 190 water & 220 oil.
Oil pressure 50-60 once warmed up to operating temp and above idle.
As for min temps 170-170.

The most important temperature is coolant. You want to see 80C / 177F minimum. This may require a 195 thermostat. See a thermostat is fully open at its set point but does not fully close until 10F below it. The spf coolant system is so huge, if you use a 180f thermostat your temps will be around 165F or 70C since your thermostat won't close before 170F? If you have one of those high performance thermostats you may never get above 160f as they never close. Get the old cheap kind that have a tiny button to let air purge. Cold cylinders and hot piston equal excessive wear. Optimism temp for combustion is 212.

As far as oil I had a Roush which had 42 psig oil pressure at 6K rpm and suffered no ill effects. Turned out the oil pump RV spring was wrong but the learning was 42 psig was enough even at 6K rpm. Anything above 60 psig when engine is hot is pure waste and increases engine wear. The heavier the oil the hotter it runs. 20W50 will run 5-7F hotter than 10W40. I never like seeing oil temps higher than 100C for any extended time. That being said if I didn't use a plexiglass plate over oil cooler in winter oil would take FOREVER to get to 70C, only time oil cooler was of value was in summer and beating the snot of it.


Summary:
Water - 80C minimum
Oil - 90C-100C
Oil Pressure 55-60 psig at 6K rpm.

Thanks for the specs, DW and MAXX.

The previous owner used Mobile 1 10W-30 in this engine, which is still in it. From a cold start, the water temperature takes 7 to 10 minutes idling to reach 80 C (177F), so it doesn't seem that this radiator has a high-performance thermostat. The oil temperature lags the water temperature during warm-up, but after reaching operating temperature, the oil temperature stays 7 to 15C above water temperature. Driving around town, the water temperature stays in the 80 – 90C (177 - 194F) range, and oil temperature 92 – 97C (198 - 207F).

The oil pressure is 60 PSI at a cold start, and gradually moves down to 42 psi when fully warm. Driving around town, it stays around 47 psi.

On a spring day last week (May, 83F, sunny,) I drove about 15 minutes on the freeway, (72 mph, 2200 RPM, fifth gear) and then hit a Texas sized traffic jam, and spent 10 minutes in stop and go traffic. After a few minutes of S & G, I glanced at the oil temp, and saw 104C (219F). Yikes! The water temp was 95C (203F), so the radiator fan has not yet switched on. I threw the manual switch, (which the previous owner had labeled 'kenlowe') and the oil temperature dropped to 100C in a few minutes.

This roadster Superformance does not have an oil cooler, and I'm wondering if I might need one? In this part of Texas, we get many summerdays above 100F. A plexiglass cover for the oil radiator does seem a good idea. The previous (original) owner lived in cool Connecticut, and I'd hate to damage this sweet sounding motor with boiling oil.

Bonus question: In what country did the previous owner grow up?

Thanks for the specs, DW and MAXX.

The previous owner used Mobile 1 10W-30 in this engine, which is still in it. From a cold start, the water temperature takes 7 to 10 minutes idling to reach 80 C (177F), so it doesn't seem that this radiator has a high-performance thermostat. The oil temperature lags the water temperature during warm-up, but after reaching operating temperature, the oil temperature stays 7 to 15C above water temperature. Driving around town, the water temperature stays in the 80 – 90C (177 - 194F) range, and oil temperature 92 – 97C (198 - 207F).

The oil pressure is 60 PSI at a cold start, and gradually moves down to 42 psi when fully warm. Driving around town, it stays around 47 psi.

On a spring day last week (May, 83F, sunny,) I drove about 15 minutes on the freeway, (72 mph, 2200 RPM, fifth gear) and then hit a Texas sized traffic jam, and spent 10 minutes in stop and go traffic. After a few minutes of S & G, I glanced at the oil temp, and saw 104C (219F). Yikes! The water temp was 95C (203F), so the radiator fan has not yet switched on. I threw the manual switch, (which the previous owner had labeled 'kenlowe') and the oil temperature dropped to 100C in a few minutes.

This roadster Superformance does not have an oil cooler, and I'm wondering if I might need one? In this part of Texas, we get many summerdays above 100F. A plexiglass cover for the oil radiator does seem a good idea. The previous (original) owner lived in cool Connecticut, and I'd hate to damage this sweet sounding motor with boiling oil.

Bonus question: In what country did the previous owner grow up?

Your temps and pressure are perfect. Stay with the 10W30. I am not a fan of oil coolers, just more plumbing, oil flow restriction etc. You are done stick with the 10W30.

CHP2RA,

Oil temperature above 100 C (212 F) and less than 110 C (230 F) when fully hot is preferable to sustained oil temps below 100 C to eliminate any moisture that might be acquired due to the combustion process. Also, modern synthetic oils are more resistant to viscosity deterioration and oxidation than conventional petroleum based oils.

I used to live in Texas and added an oil cooler after one summer when sustained ambient air temperatures exceeded 100F for several days. Under those conditions, my water temperature rose above 212 F and a noticeable drop in oil pressure was experienced in stop and go traffic. Now that I live in SoCal, I doubt that I will experience those conditions again.

John

Mine was a Roush 427IR. I was losing coolant until I added a expansion tank to the coolant system (I got one of those beautiful Kirkham billet ones). In city driving the temp was high while on the highway it wouldn't warm up. The radiator is so oversized that I went to a higher range thermostat (190 I think) and that helped a little. However, the engine oil cooler then became a secondary radiator and prevented oil temp from getting much over 180. Some people here discussed a thermostatic bypass for the oil cooler but I don't know where - search might find it but there are so many topics on "oil cooler" that it didn't jump out. I do recall there is a JEGS part that is used. I sold the car before I put it on (it was going to be a winter project) but I suspect if the oil cooler were tuned to balance oil and water temp that the thermostat could have been backed off.

As an aside, since it was mentioned, i would seriously avoid sitting and idling anywhere near 10 minutes at a clip. It'sa rare engine that won't experience more wear under those circumstances.
Give it a minute or two and drive off slowly until temps come up. Easier on engine, trans, and diff.

Hey Tim, thanks for the idle warning. I had been letting it sit for 10 minutes idling, and was fearful the fumes would start a fire. This morning I cranked it, and within 2 minutes the water temp unpegged, and off I went, slowly. You just saved me a lot of time, cumulatively.

You're welcome. Always a plus when all systems fluid temps come up to operating levels at pretty much the same time.

I once installed a oil cooler, ended up blocking it off because to would never warm up.

DW, you don't mean that the oil temp wouldn't warm up with an oil radiator IN PHOENIX? I've been to Phoenix and I couldn't COOL OFF! I needed a blood radiator!

Hi JHIRASAK, Thanks for the word. If I understand you correctly, oil temp up to 110C is ok if I'm running a synthetic oil, as long as the water temp stays below 100C. So far it has.

LOL,
We don't drive much in the summer here, just to hot for the body.

Tim...this is a good point. I have a couple of friends who let their performance cars idle until hot then drive.

I hate doing this in general and have taken the path to gentle drive keeping the rpms under 2500 until reaching temperature.

Jeff

Oil does not work correctly Until it reaches about 212.
Briefly getting oils up 250-260 will not hurt anything either according to very knowledgeable people at Gibbs.

Gentlemen, thank you all for your guidance. I emailed Roush Performance Engines with the same question at the head of this thread three weeks ago. Mr. Mark Yagelo responded quickly, but SBCGLOBAL didnt deliver his response until recently (sigh). The Roush response was:

Generally speaking, we'd expect 25-30 PSI at idle with the oil hot. From there, you need 10 psi/1K of engine RPM. So at 4K RPM, min PSI would be 40 and at 6K RPM, you want to see around 60 PSI. Max oil temp for normal operation is 230F and water is 210F.

I told him the previous owner used Mobil 1 10W-30, and asked his thoughts on oil for this engine in a weekend cruiser. He said:

10w30 conventional from a reputable source. I like Castrol GTX in my personal vehicles.

it never ceases to amaze me the bias against synthetic oil in classic cars. Dang, they need the good stuff a whole helluva lot more than the modern engines do/
of course the naysayers are generally those who make some money when your engine is worn out, something that a good synthetic oil will delay by 100,000 miles or more. When I working on engines professionally. I enjoyed saving my clients some $$$ by using and recommending synthetic oil in their cars and motorcycles.
Z.

On my road race car (331 stroker,solid roller cam),I'd let it idle to warm up,idle rpm was set at 1,000rpms....once the water temp got in the 150+ range and oil temp was in the 125 or so range,I'd go to the end of the paddock and do figure 8's at about 2500 rpms to warm up the trans and rear diff. and also drag my left foot on the brake pedal to get some heat in the rotors and brake pads.......Once water and oil temps were in the 180 range, I'd go park it and get ready to go on track....when called to grid,I'd let it idle till water and oil temps were at 180 if possible before going on the track....

30 minute race in 100 degree heat of the summer would see my water temp at no more than 185,but my oil temp sometimes was as high as 260,mostly ran in the 230 to 240 range.....that engine ran 8 seasons like that with no apparent problems..........I was using Mobil 1 synthetic 15/50 oil....

On my street car engine (331 stroker,hydraulic roller cam), I will let it idle until the water temp is around 140 or so and the oil temp is just coming off the peg at 100 degrees,then drive it easy for a few minutes till water temp is at 180 and by then oil temp is around 140 or so....the oil temp will continue to come up with driving until it levels off around 180 to 190 with normal street driving.....
been doing this since the late 90's on this engine and it has just shy of 40,000 miles total........at least 200 drag strip passes, and 2,500+ miles on 4 different road courses......it's just starting to "use" about 1/2 quart of oil every 2,500 miles which is not bad considering how I have used and abused the engine.....using nothing but Shell Rotella T diesel oil in 15/40 weight....

david