Tomahawk Build Article - Enginebuilder Magazine

Discussion in 'Tomahawk Block Buildups' started by Steve Schlater, Aug 5, 2017.

  1. Steve Schlater

    Steve Schlater Well-Known Member

  2. cjeboyle

    cjeboyle Gold Level Contributor

    Thanks for sharing. Very cool
  3. slimfromnz

    slimfromnz Kiwi Abroad

    Failures with the aluminum block engines? where?
  4. Jim Weise

    Jim Weise EFI/DIS 482

    There has been a couple. My personal belief is they are being hurt on the dyno. While they have not failed on the dyno, they have very shortly after being installed in the car, and making a few runs. These have been high HP race builds, these are the hardest on parts and closest to the "edge" so one would expect to see the failures there. I have to say that I have not personally been involved in any of these engines, but I can read a dyno sheet, and know that brand new alum rods just don't break for no reason.

    Oil return/supply and aeration issues is my theory. The last one I did, I opted for some fairly radical changes to the block, along with new design scraper/windage tray... it's the first one I have seen that actually has an oil pressure curve in it (oil pressure goes up with rpm). Most Tomahawk dyno sheets you will see have a flat oil curve (pressure stays the same as rpm goes up) or the pressure actually goes backward with rpm. Both those are signs of an issue on the supply side of the pump.

    While most of them are living with this issue, it's an indication that something is just not right. Small bearings and priority oiling help for sure. The three I built previous to the latest one had this issue, but lived just fine.

    Does not matter if it's a wet sump with a belt driven oil pump, a true dry sump system, or a scavenger system. Seen this flat oil curve on all of them.

    The last project got rushed to go in the car by the owner's personal issues, so it never made it to the dyno, wish it would have, I would have a dyno sheet to show the oil pressure curve.

    But the next couple are right around the corner here.

    As far as the Tomahawk program here, it was a break thru.. especially considering the fact this is an internal pickup motor, with a stock oil pump. It validates my theory of supply side issues, as the stock style pump will flow enough oil thru the internal passages to meet the bleed rate of the engine, and build pressure with rpm. And I don't build them "tight", because the block is aluminum.. tried that with the first one, and got away with it, but when it came back 400+ passes later, for a normal freshen up and upgrade, I saw the error in that thinking.

    I can tell you that building a Tomahawk, only slightly resembles building a Iron block Buick. Lots of different procedures and concerns.

    Going back out to work on the next one... right now..

    Julian, Stage2Scott and slimfromnz like this.
  5. Todd69GS

    Todd69GS Silver Level contributor

    Jim, that is a very interesting post.....and very concerning to everyone with a Tomahawk block I'm sure. This block was supposed to be the answer to all of our problems as far as building a Buick race motor goes. And here we are talking about some oil related failures. I understand that there is always a risk in building race motors as mechanical parts can fail but it seems like this may be something different.
    In your opinion is the aeration more of a concern or the supply side of things? And if it's supply are we talking about a restriction/flow issue in the block?
  6. Jim Weise

    Jim Weise EFI/DIS 482


    There is no question that the Tomahawk is a huge step forward in engine durability.. That first one I built in 2010, came back with what appeared to be detonation issues, showed up as a main bearing that was deformed, and some cratering of a couple pistons tops.. it was right on the edge, most likely a minor tuning issue, or fuel supply problem that was fixed before it got out of hand.

    But it came back in one piece, was an easy fix... an iron motor would have come back in a box... regardless of who built it and what you did to strengthen it.. detonation was the killer of a good majority of the serious iron block race motors out there.

    On track, there is actually much less of an issue with oil return.. on the dyno, there are no forces acting on the oil in the pan, so it can just hang around in the upper end, and the front of the oil pain... not in the sump where you need it. Even dry sump systems have a hard time sucking it out, as they really rely on oil return to the pan, more than you might think.

    My opinion is we have both going on here, lack of supply side volume due to oil not returning in a stationary engine on test stand, and the quality of the oil returning is possibly not the greatest, being somewhat aerated. The aluminum block, by virtue of it's design, due to the material, has tighter oil return spaces, than does the iron motor. That's what happens when a motor with nearly the same external dimensions, gets the "more beef" that we always cried about not having.. and then gets made of aluminum to boot. Look at the bottom end of a Tomahawk with a big stroke rotating assembly, and you will see that very little oil makes it back to the pan, without hitting the spinning crank.

    I addressed both those issues in the latest build, and on my test stand, results were great.. oil pressure rose with rpm, just like it should. But without the load against the motor I am hesitant to conclude we have eliminated the stationary oil return issue. And of course, in the car, with G forces pushing the oil back in the pan, it works great.

    The next one will tell the story, it will see the dyno.

    Now with these engines in cars, there have been very few issues... and they all happened right away, which leads me down the road of an idea that the genesis of the problem starts with testing a stationary engine.

    Case in point.. the very first one I did the oil pressure actually went backward... you think your a bit concerned now.. try standing in the dyno cell with a customer who just shelled out 15K for a new shortblock, and watch the oil pressure go backward with rpm. I was fit to be tied... and after the session, I just went home and sank into my couch... defeated..

    I did not make a real big deal about it with the customer, because I had seen this before, where the motor has better oil pressure on the track, than on the dyno. Big stroker iron motors usually.. So I was hopeful.

    Phone rings a couple weeks later, it's the owner of the very first Tomahawk built.. he has it in car now, and is running it at the track... I see the caller ID, and figure... OK, here we go....

    To my surprise, it was just a performance report, and a couple minor questions. As we were finishing the call, I just ventured a question about his oil pressure in the traps. It was falling off dramatically at 6300, so I would not let Ron pull the motor any higher on the dyno.. remember, this is the first one build, so no one yet knows what they need for oil pressure.

    Anyway, was very happy to hear that the motor that had 62 psi and falling on the dyno at 6200, has 90+ psi in the traps at 6800 rpm... It was the first indication to me that we have a supply side issue to the pump. And maybe a windage issue, not uncommon with a motor with a long stroke. An issue that really shows up on the dyno.

    That motor had the TA scavenger set up on it, with stock length gears.

    We did dyno it right away when it came back for a freshen up, after 425+ quarter mile passes.. Time for a set of new Alum rods, and while we were at it, we did development work on a new set of heads, and a different intake. I also added a windage tray to the oil pan in the subsequent build.. It was better on the dyno this time. Here's a graph of the progress we made, that I put together for the customer.

    oil pressure history.JPG

    This is a graph of oil pressure.. for the first Tomahawk, at the initial dyno session, the session we did to study oil pressure and high rpm HP before it was rebuilt, and then after the freshen up/upgrade... the number behind the "555TSP"in the legend, is the pull number for that particular motor, since we first built it. You see we have been doing some dyno development, with over 60 pulls on that engine now.. I just happened to pull number 48 for that last graph.

    Pull 4 is when we first saw the issue. It left with that curve, but as I had hoped, cooler oil, that is typical during drag racing (oil was 170-180* for those dyno tests). along with the forces on the oil with the engine moving forward rapidly, allowed this motor to go to 80-90 psi, and just hang there thru the run. So it lived just fine, even at almost 7000 rpm.

    Pull 19 was after it came back, 400 plus passes later. Oil pressure is lower because during testing, after we more or less stablized the oil curve, I switch from 20W50 to 10W30. The only physical change beside that, was an extra 2 quarts of oil in the pan (10 quarts, standard rear sump Steve Reynolds Tomahawk pan)

    The final graph is with the windage screen, installed in the pan. Also, it's considerably different, because I abandoned the "oh, it's aluminum so you have to build it tight" philosophy, and built with more conventional alum rod race motor clearances. 8 quarts of oil in the pan, this time, adding oil did not help. So more of a windage issue than a volume one..

    We have greatly stabilized the oil pressure now, and have the start of the right looking OP graph, but more work needs to be done. Not on this engine, because remember, put it in the car, and it works differently. It's been happily terrorizing the opposition in an 8 second/157mph 81 Regal for the last two years..

    The next one out of the box, a 768HP street motor, was the first one I had built with the internal pickup, and stock pump. So kinda a toe in the water, so to speak... just testing to see what would happen.

    It showed that we could use that pickup, and was promising. Had an SRE fairly elaborate windage screen bolted on the main caps, 10-30 oil and a stock gear length pump. Held pressures to 65psi, with a farly flat curve from 5000 to 6500 rpm. IN car, we switch to 15-50, and it worked great, just starting to show signs of the right oil curve, going up a few pounds with rpm.

    Next up is the latest one, which incorporates substantial oil drainback mods, a completely different crank scraper/windage tray design, along with a high volume oil pump and 15W50 Joe Gibbs HR-1. Oil pressure gauge is like it's hooked to the tach... idles at 40psi, and would peg my 100 psi gauge on the test stand, till I calmed down the relief spring pressures..

    Works the same way in the car, even with 180-190* oil. Not that I am staring at the oil pressure gauge, while rowing thru the a couple gears of the 5 speed, in this 64 Lark.. At aprox 750HP, this thing is downright scary, even on big street tires, at 3/4 throttle... I am not brave (or stupid) enough to mat it.. too much respect for a customer's equipment, and fear for my own life, I guess..

    IN any event, this new motor, like any new performance item, has a learning curve to it. I smile and nod my head at those who have "it all figured out" in one or two builds, but that's fine.. no skin off my rump. I do know that now finally I could get the 160lbs paperweight off my shop floor, that was the Tomahawk block for a board member's EFI/Vortec Supercharged motor.

    No way that high HP combo was going together, until we understood the oil pressure issues better. But it will be ready to hit the dyno next month, unless I do something stupid and injury my knee again..

    So if your building a high HP force fed 'hawk, have a solid plan for your oil system and don't abuse it on the dyno, to get a number, and you should be fine.

    Priority oiling or no, 50 psi on the dyno at 7000 rpm, is not a place you want to be.

    Last edited: Aug 30, 2017
  7. Todd69GS

    Todd69GS Silver Level contributor

    Good read Jim. I feel better now. Thanks
  8. TA Perf

    TA Perf Member

    It seems like some post have been removed from this thread since I first read it.

    There have been folks that had problems, most from lack of attention in my opinion and then the lack of follow through. Things happen when someone is running a business, this is just a general statement.
    Oil pressure;
    If oil pressure is going backwards during any sustained rpm its almost always from aeration. Remove any "screen" you have installed around the crankshaft. A windage screen will cause the oil to become super aerated on a run stand, dyno or anytime the engine is being run up in rpm. Your idle oil pressure will also drop after the pull. Shut the engine down for 3-5 min, start it back up, and the idle pressure will now be higher. The few min will let the air rise in the oil and allow for a clean oil supply, idle oil pressure will be higher. The air will cause the oil pressure to be unstable and drop if aeration is occurring. I have had better luck running just a open deep baffled pan, let the oil get as far away from the crank as possible. I have spoke with the mfg of these pans about a louvered windage control . Screens act as a large bubble maker in my opinion when not submerged in oil.
    Flat oil pressure curve;
    I would think if everything is working as it should the curve should be flat. A pressure relief should maintain a number of pressure if the pump is doing its thing. My engine may spike to 80-85 on launch (Lenco 4 speed) drop and maintain 65-70 through the rpm range up to 8500 rpm. Honestly I have not played around with the pressure spring since I switch to the aluminum block. If the pump can not bypass properly the oil pressure should continue to climb with rpm.
    Oil return ports;
    Its was up to the builder to take care of this. The very early blocks had NO oil return ports in the lifter tray area. This way builders could leave this area alone for a dry sump and scavenge the lifter tray or for wet sump they could drill return holes. Well, I felt that was a great idea but a few put them together with no return holes on wet sump engines, and all the oil ended up in the lifter tray. Ok, then I started drilling four 7/16 return holes which can be tapped for 1/4 NPT. This hopefully would catch folks attention and either plug them or enlarge them or drill more. That didn't seem to work, so now there are 4 more 37/64 which can be tapped for 3/8 NPT for a total of 8 return holes, 6 of which are toward the rear of the block. So, please look at your block and give it some thought as to what it's going to be used for.

    Bearing clearance on these blocks are very similar to the iron, .0027 to .0032 mains. I have found main bearings to play a roll into oil pressure as well, Mfg, style etc...
    Lifter bores, if it were up to me I would sell every block with undersized lifter bores but customers have expressed a big NO to that and its either all or none. It's not a huge problem, just an area theres no control over, on another note the builder/machinist could make it very much worse fitting the lifters, so for now its been left alone, I still may change this at some point. This is an area for more oil control, tighter lifter bores. Lifter bores can be bushed if you feel there is a problem.
    The top rear of the block has an oil manifold with oil restriction capability. Also, we can provide custom pushrods with one end restricted as low as .010" I believe. My wagon engine runs restricted pushrods. This will help keep oil from the top side of the engine which is somewhat necessary when there's only so much in the pan.

    I been through this, I've talked with most everyone that has had a concern. I'm here to help. Just remember, you can call me.
    Last edited: Sep 3, 2017
  9. hugger

    hugger Well-Known Member

    Thanks Mike
  10. Jim Weise

    Jim Weise EFI/DIS 482


    Nope, no posts are missing from this thread, I would be able to see that.

    You must be thinking of another thread.

    Thanks for the input.

    Last edited: Sep 2, 2017
  11. Todd69GS

    Todd69GS Silver Level contributor

    Thanks for chiming in Mike.
  12. TORQUED455

    TORQUED455 Well-Known Member

    I don't think the block failing is an issue. Care has to be taken to build the engine correctly, and the failures reported are likely "build" failures. There is a lot to learn on the first few builds. There are discoveries along the way, and it seems that items that are a concern on one block may not be a concern on another, depending on the build and parts going in. Oiling on my Tomahawk build was scrutinized by Keith and Duane Diabo, and information that they discovered and how they discovered it was truly ingenious. I had mentioned that I thought we were supposed to be leaving the oiling problems behind with the iron block, with a 3" main and priority oiling on the AL block.

    The article touched upon my build and now Ken Montour's build, but some of the stuff is "classified". It takes a lot of R&D ($$$ by Ken and myself) and a dedication to the craft by the Diabo's to selflesssly get the results desired rather than obsessing with the business end (aka a lot of OT that didn't make it on the invoice). I think Duane was sneaking back into their shop on nights and weekends when porting my heads, and probably using a flashlight so Keith wouldn't see him lol. Duane would have an inspiration, and he kept after it until he was satisfied.

    The Tomahawk certainly has opened a lot of new doors for a lot of people. No one would even dream of making the power that we can make now w/o eminent block failure right around the corner. With new heads in the works, who knows where we will end up in a few years.
    300sbb_overkill likes this.
  13. hugger

    hugger Well-Known Member

    Was oiling system info withheld ?
  14. TORQUED455

    TORQUED455 Well-Known Member

    From TA? No.
  15. hugger

    hugger Well-Known Member

    Nah from the article
  16. hugger

    hugger Well-Known Member

    My phone is being stupid and won't load the article, only reason I ask is withholding cam and head flow tricks, RanD I can understand but if something is found that will keep guys from loosing LOTS of money IE Oiling tips, that should made public imo. I'm not say they did just saying,...
  17. TORQUED455

    TORQUED455 Well-Known Member

    They didn't, but I can't see why someone would give away their stock in trade... if you are uncertain about building your Tomahawk, call Mike.
  18. TA Perf

    TA Perf Member

    Thank you. The Diabo's are great folks, Keith gets a little excited at times, but once he gets his thoughts off his chest he's the first to give out a hug. They both think through there builds extensively and stay in contact with me on areas of concern. Without folks like the Diabo's it would be harder for all, because I listen to them. I then do what I can to make things better. If I remember my reading of the article, it seemed to me the article brought out more concern than needed to be, but if you knew nothing it would make you at least look harder, I think that's what the Diabo's were looking for. But, it seemed to scare or raise a concern that was thought to be nonexistent with the new block. Remember folks, every build can bring on situations whether it's with proven or unproven parts. We didn't get to where we are today with one build, it's work in progress, always.
    Last edited: Sep 3, 2017
  19. TORQUED455

    TORQUED455 Well-Known Member

    Keith and Duane wanted me to clarify - they don't feel there are ANY oiling issues with the new block, and that's why it wasn't mentioned in the article.

    MY perspective is that if all areas of building these things aren't scrutinized, including the oiling, then failures can and will occur, and the more power that is made means the less room for errors. Heck, failures can occur even if things ARE scrutinized. However, how they came up with the oiling system on my AL engine (knowledge that is now being used on Ken's build), was ingenious and I've experienced absolutely no oil pressure issues, no backwards pressure, etc. I wish my own build in my other Buick had as good of an oiling system. Matter of fact, I see Keith peeking at the oil pressure gauge when we go cruising in that car when he's in town for a visit. Next year, I'm putting a piece of tape over the damn thing lol.

    ROCK N ROLL GSX Well-Known Member

    Building these new aluminum blocks is pretty exciting. Mike T contributes his share of the excitement when we call to relate our "discoveries" with the aluminum block builds.. Mike always takes the time out from his busy schedule to talk to Duane and I, sometimes for hours,and we appreciate that.Mike has always been a good friend.Willing to help us with our projects and showing real interest.There are really no tricks or secrets to these aluminum block builds.
    Just common sense and being careful when building them.Spending quality time on them. Not rushing through them.Double checking all the machining and clearances, doing a lot of R&D and being in contact with other engine builders and making an effort to find out what is the latest and the greatest.Everyone has their own ideas on how to build these engines and what makes them tick.I will say the key most important element of our combos are the cylinder heads.We have tried different strokes and it always seems to be the cylinder heads that make the power no matter what stroke .Duane has been porting cylinder heads for 30 years now. And is presently getting 384+ CFM with Ken's Montour's STAGE 2 SE heads.With out killing the low and mid lift numbers.Peak numbers have been better on our "test" heads but these ones have the best combination of "over all" flow numbers.We are checking on three different flow benches an SF 110 SF 600 and more recently on an SF 1020.Bob Ortolani and Ken Montour are very involved in these builds too.Bob is being modest about his contributions to his project. With out him his combo wouldn't be the success it is today.It is really kool to visit him and drive around on the street with his GSX.The oil pressure stays high and the operating temperature stays low.Even with tape on the gauges LOL.It amazes us how the car can run so well and make so much power yet be at home on the street.But with a 10" 3500 stall converter and in street trim and full exhaust it is possible.We are looking forward to going to the track with Bob and do some tuning on the car soon.We are looking forward to completing Ken Montour's aluminum block build.No predictions.Just going to try and do our best.
    Julian and 300sbb_overkill like this.

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