Thanks in advance for experience-based answers.

Car - 99 FRC w/403 autocross & track car. Ron Davis radiator w/internal cooler & AN -10 hoses/fittings. Mobil-1 15-50. Melling HV oil pump.

Symptom - Oil pressure max is 55 around 4,500 RPM. At 6,500 RPM pressure has minimized at 41. Drop is linear above 4,500. Note, idle pressure is 33 with oil temp at 200 degrees.

Questions - Has anyone experienced a RD internal oil cooler restricting flow? What am I overlooking?

I hate throwing $$ at random. My thoughts - (1) Eliminate oil cooler to see if there is a difference, but I will have higher oil temps. (2) Change block adapter, but it probably won't do anything. (3) Change oil pump, and this too probably won't do anything.

 

I agree you should get rid of the oil cooler to see what happens. Running it short term like that isn't going to hurt anything.

 

When I installed my Dewitts Rad/EOC I shimmed the oil pump to get the ~5psi back that I lost.

 

This issue is very common and everyone wants to either ignore it and try to fix it the wrong way. I've posted the problem and solution at least five times and nobody ever comments but here it is again.

The oil pressure sensor is at the end of the oil circuit, so it measures what pressure is left after pushing through the motor galleys. So the gauge reads the final pressure which which is Pump Pressure - engine pressure drop = gauge reading. Add in the EOC and you have PP - Engine -EOC = Gauge reading

Now here is the item everyone misses or doesn't care about....
Internal (inside the radiator) EOC's are not designed for full engine oil flow!
The oil pump can put out 6-8 gpm at high rpms and the eoc is rated at about 2-4 gpm with about 10 psi delta P. When you cram all the oil (6-8 gpm) through the oil cooler the deltaP goes to 50-100 psi drop, and that leaves nothing left on the gauge. 99% of the people think they can solve this problem with larger diameter hoses but the hoses are not the problem and they will only remove about 3-4 psi.
The solution is a simple 7 psi bypass check, just like they use in C6 Corvettes with Z51's. It's really a beautiful thing...the eoc works great at idle with 2-4 gpm and when you rev the motor and the flow increases, so does the backpressure. When the backpresure hits 7psi, all the extra oil bypasses the eoc and takes the normal oil path. This maintains a constant flow through the eoc at any motor rpm.
The factory C6 Z51 hose assembly will fit a C5 but it does not have a port for the oil temp sensor, so we put one in. The only negative to this part is that you have to disconnect the driverside motor mount to get it in there but I think the benefits far offset this problem. We also had special quick-connect fittings made that will screw right into the eoc and mate up with the hose assembly. Here is a link to the part, but more importantly check out the link on that page for a circuit to see what I'm talking about here.

http://www.dewitts.com/pages/product...asp?ProdID=429

 

Tom,

I have your original adaptor block with the 5 psi valve. I had to masage it to fit my headers. I'd like to replace it with your new setup. What else will I need? Do I take the 45 degree fittings out of the radiator? Do you have them in stock? Now is the perfect time since the motor is out.

Please PM me.

thanks

Rob

 

Rob,

Why do you want to replace the adapter? You already have a bypass?

 

Cleaner install than the 10-an lines. Plus the mounting block is right on the header. I am sure some heat is transferring.

 

Ok, just wondering. We have the kits in stock