I finished assembling my procharged Tomahawk engine this winter and have had it running in the wagon for awhile now. I've put nearly 100 street miles on it and roughly 10 passes at the track. The only issue I've experienced is what I believe to be high oil temperature. My previous iron procharged engine would run oil temp at 180-200 degrees on the street, occasionally creeping up another 10-15 degrees stopped at a light but then immediately dropping once you're back underway. This engine seems to heat up fast, it's at 150 in maybe 5 minutes of run time, idling in the driveway, and keeps climbing to 240-250 degrees on a 15 minute drive. Same thing at the track. By the time I drive to the staging lanes, it's at 180, 210 by the end of the burnout, and 240-250 on the return road. The other day I installed a fairly large oil cooler (18" x 7" x 1 1/4") fed by -10 lines using one of those filter housing sandwich plates. As far as I can tell, it did absolutely nothing. Took it for a drive in 80 degree weather and oil temp climbed to 240-250 again. The only possible difference I saw is that it seemed to stabilize around 240 if that makes sense. These temps were verified with a handheld temp gun, after stopping the engine and measuring the outside of the pan, the lines, cooler, etc. I also had the car up on the lift, running, and checked temp in many points while idling. Other than the oil cooler, I've also tried varying the oil level. It's got one of Steve's 10 qt aluminum pans and I first started with 7 qts, than 8, then 9 with the cooler and now 10 with the cooler. The cooler and lines hold roughly a qt. No change in slowing down the warming of the oil and no change in maximum temp seen. I shpuld note that the sandwich plate has a thermostat control internal to get the oil up to temp before pushing it through the cooler. Oil pressure has been fine even at 240 degrees. Nearly 50 lbs at 2000 rpm cruising around, 75+ going through the lights at 6500rpm. Idle at high temp is still 15-20 psi. Oil used is Mobil 1 15W-50. Info on the build: 464 with JE pistons, 38 cc dish, 7" GRP aluminum rods, stock crank cut to 3" main Bearing clearances are .0038" mains, .0032" rods, King main bearings, Clevite rod bearings Piston wall clearance is .0045" Using the in pan oil pickup, SRE pan with baffles and louvered windage tray, TA cover with a stock oil pump, same oil pump/cover setup from my iron motor #64 jets in the restrictors at the back of the block The engine went together with no issues, nothing looked out of the ordinary. I'm looking for suggestions on what to check next, opinions on oil temp and other's experiences. There's a lot of info from oil manufacturers that state conventional motor oil is good to 300 F while synthetics like the Mobil 1 are good to 400-450 F. Car is already in the trailer so anything internal will have to wait until after the Nationals.
That's "discouraging"! I have issues with my Procharged Tomahawk also, but mine is getting it to Rev past 5k. But, as I recall, my engine oil Temps have only gone up to 100-150°. Water Temps are 185-195° tops, but I am running E85. Hope you can figure it out!!!
I have the same issue Paul. The oil runs hotter than normal yet water temp is fine. I haven't worried about it since it does seem to max around 240 as well. I just try to get off the track with it around 200 max. Don't know if it matters. So many conflicting things on oil temp. I wrote it off as so much under hood temp from the charger as well it just can't dissipate fast enough. You open the hood and it's like a sauna escaping. John jr
We have seen this since I built the first one 13 years ago. The Tomahawk very much mimics a filled iron block, in it's ability to shed heat from the oil. I believe this is because it has so much less water in the block, due to the thickness of the casting, and the size of the bores. All that took up water jacket area. Because of design constraints of the engine size, they could stretch it out a little longer, but not widen it significantly, so the water jacket area could not be increased back to what the iron block has. And for all the bitching we do about our thin walled iron block, the one thing they do well is transfer heat from the oil to the coolant, until you fill it with grout.. I consider this as a normal characteristic of this engine block, and as long as your using quality oil, and can maintain pressures, then not a real issue. I advise drag race customers that they need to stabilize oil temp before the first pass to determine their dial in. I have seen considerable power differences that accompany varying oil temps. Paul, as to the cooler making no difference, three things to consider.. Type of cooler, speed at which the oil is passing thru it, and airflow. A stacked plate type cooler ( like the B&M supercooler) in the largest sizse they make would be what I would use. Can't really do much about the speed of the oil passing thru it, without hurting flow and the resulting pressures. And for a drag race car, I would recommend a small dedicated fan attached directly to the cooler, pushing air thru it at all times. JW
I should also mention that I have used a lot of different oils over the years, and Valvoline VR-1 is by far the worst when it comes it comes to viscosity breakdown due to oil temp. I don't recommend it for anything beyond just a stock type build, and even then your better off with an oil that is more thermally stable. JW
Bummer on that VR1 info....I use it in all my performance stuff. 9 seasons on JAGUICK motor with no freshen up.....on VR1
Not saying it won't work, just reporting info gleaned from dyno testing over the years. As always you can do what you will with my recommendations... JW
What it comes down to is the aluminum block is a drag race purpose block. If you want to drive this on the street for any real distance you would have to run a dedicated oil cooler with fan. At those oil temps that block Has to be growing a lot!
I don't think 240° oil temp is that bad? I had a turbocharged audi with an oil temp gauge and it would hover at 220 all day. Anything with a turbo cooks the oil at exhaust temps! maybe it would be worth a call to the oil manufacturer to see what they consider trouble?
Ken, I use and recommend Joe Gibbs driven oil. BR 30 for break in and HR-2 for normal street/race use. For a high temp deal like the Tomahawk, a full synthetic like Driven XP 6 would be recommended. Here's the bullet points on XP-6 * Designed for aluminum blocks and looser clearances * Works well in both wet or dry sump engines * 410 sprint engines * Hydraulic lifter wet sump engines * Ford and Dodge crate engines * Off-road truck engines * Engines designed for SAE 50 weight oils * Engines operating with oil temperatures from 240 to 320 degrees F JW
Thanks for all of the comments guys. Some additional info I didn't add in the initial post - water temp has not gotten higher than 170 degrees even idling for 10-15 minutes at 80 F ambient. Also, as John noted above regarding inlet temps, I shot the heat gun at both the carb hat and the intake tube leaving the procharger after I had made a 15 minute drive, so oil was at 240 F. Air inlet temp from both locations, at least on the outside of the parts was a whopping 175-180 F. Note that I do not have an intercooler and the distance from procharger outlet to the carb hat is a short ~18" or so. I was surprised to see it that high. Jim, I have been looking at the stacked plate coolers (and still am) but in the interest of time in getting everything ready for BG, I just grabbed a large, cheap Hayden two pass cooler to see if it would help. I also have it mounted by itself at least 2" in front of the radiator to try to give it the most airflow. Using the temp gun, it is definitely doing something, just not enough to make a substantial difference. I measured inlet temps to the cooler at 220-225 F and outlet temps of 175-185 F, so a solid 30-40 degree drop. Since I have signed up again for Drag Week this year, I will be street driving this quite a bit so I see a constant fan driven, large stacked plate cooler in my future. Any comments on oil quantity since I've tried various amounts, understanding that more is certainly going to help dissipate the heat? But I don't want to get into a situation where the crank is basically sitting in oil. Tom, you are not kidding on the growth at those temps! That's why I've been paying close attention to the pressure. It seems a lot of the circle track guys and even IMSA/SCCA cars have no problem running oil temps at 300+ for lap upon lap at 5-6000 rpm or more. I figure I'm only running high temps for a couple of minutes from staging to return road and most of that time is just at idle or less than 2000 rpm to get back to the pits.
Do you have a magnetic drain plug, does it show any thing on it? Fuzz is ok, grit is not! I would send a oil sample out for testing before heading out to the track again . Where is the color change over point on your plugs ground strap, can you post a few pictures? Here's a chart of how long a mineral based oil last in regards to temp, a synthetic oil is good for much more life.
