What's the deal with engine and tranny reliability?

[Kurt Bilinski]

I worked the enduro on Saturday and was surprised by the relatively poor reliability of the bike powerplants.

My thoughts are:
1. Are these engines dry-sumped in FSAE cars? I suspect not, and wonder how they can last as long as they did without one. Seems like oil slosh, not present in the bike, would be a real problem, as UO can attest.

2. Why did two (that I know of) transmissions eat themselves? U of Hawaii was especially sad, sounding like someone left a pair of pliers in their gearbox. Seems to me that bike trannies in a car have a very difficult time due to having about 10x the traction. In a bike, the rear tire just spins, venting off the torque. In the car, though, all that torque has no where to go -- and starts eating gear teeth. Or, is it simply poor shifts by the driver?

I guess my real thought is, is this size bike engine and tranny appropriate for the fictious weekend racer product? Or is a larger engine more appropriate if for no other reason than reliability. I'm curious for your comments.

[Kurt Bilinski]

I worked the enduro on Saturday and was surprised by the relatively poor reliability of the bike powerplants.

My thoughts are:
1. Are these engines dry-sumped in FSAE cars? I suspect not, and wonder how they can last as long as they did without one. Seems like oil slosh, not present in the bike, would be a real problem, as UO can attest.

2. Why did two (that I know of) transmissions eat themselves? U of Hawaii was especially sad, sounding like someone left a pair of pliers in their gearbox. Seems to me that bike trannies in a car have a very difficult time due to having about 10x the traction. In a bike, the rear tire just spins, venting off the torque. In the car, though, all that torque has no where to go -- and starts eating gear teeth. Or, is it simply poor shifts by the driver?

I guess my real thought is, is this size bike engine and tranny appropriate for the fictious weekend racer product? Or is a larger engine more appropriate if for no other reason than reliability. I'm curious for your comments.

[mtg]

A 600cc supersport bike engine is fine for the weekend autocrosser. Most of the problems I've ever seen with FSAE engine reliability come back to either inadequate oil supply or some other dumb mistake (like using an engine that looks like it sat on the bottom of Lake Erie for awhile).

As far as oil systems go, when I was in school, we did a stock wet sump with chopped pan (2003), a super chopped oil pan with wet sump and Accusump (2004) and a homebrewed drysump (2005). All three of those setups had LOTS of drivetime on them.

The 2003 setup pretty much worked fine, every once in awhile you'd get a blip of low oil pressure in a corner, but I don't really remember it shelling engines.

The 2004 setup (once we put the Accusump on) worked perfect- the oil pan was about 1" deep, we never saw any oil pressure drops, and as a bonus we even had oil pressure on engine startup.

The 2005 setup blew up a number of engines. In fact, the UMR team DNS'd enduro in Detroit last month because of the dry sump system (an evolution of the 2005 design) and converted back to a wet sump before Fontana. They still DNF'd enduro in Fontana, but this time it was electrical. *beats head against wall*

I'm not saying dry sumps do not work on FSAE cars, but if I was going to build one for myself as a weekend SCCA autocross car (or to take to FSAE for that matter), I'd do a wet sump with a thin oil pan and an Accusump. The effort spent on making a dry sump work on an FSAE engine that was orinally wet sumped could be put to better use in my opinion.

All in all, I did tech inpection 3 days at West, watched all dynamic events, and it was painfully obvious that simplicity = reliability.

I think the OU guys said overheating caused their "blowed up motor", not oil sloshing. Correct me if I'm wrong.

Btw, the kimini is pretty cool.

[drivetrainUW-Platt]

Dry sumps dont work and people loose oil pressure.

Bikes dont have near the cornering forces that a FSAE car can have (2 vs 4 tires for stability) hense the oil getting slashed around on corners, pickup for pump is starved, loose oil pressure.

FSAE cars weight alot more then a bike, clutches and trannys dont like that.

People have bad tunes.

Bad drivers.

Almost all engine fires happened because a rod went through the block and oil got on the header....and the oil issues are what made that rod disconnect from the crankshaft.

Some teams do modify the internals of the engines to squeeze out more power, if not done right this will lead to failures as well.

On the trannys, it might also be the differential/chain drive causing problems. The chain tensioning and differential housings are student designed/made and are not perfect.

I am sure there are many many more.

[drivetrainUW-Platt]

ha, ask and you will receive....

Darn bit on the differential, otherwise I would have beatcha Matt!

If you look at the abuse that the engines are going through overall with the heavy cars, heavy abuse, heavy cornering/accel/braking, bad tunes and look at how many engines are still running after competition (not counting failures of things external to the engine) I would give them a lot of reliability credit. Many teams do bring back the same engines 2 years in a row.

[John Grego]

The transmissions are made for a bike with one round tire having a small contact patch that will usually do a wheelie if you get on it too hard. These cars have two 6-8 inch slicks with a contact patch about the size of your hand. Our transmission problems have come from down shifting. Some teams don't use the clutch when down shifting and if the driver isn't careful it is easy to put it into 2 gears at once and shear the teeth off of the gears.

[John Stimpson]

I think the bike engines/trannys have really shown their reliability and durability as well. As mentioned, these machines are designed, built, calibrated, tuned and set up by amateurs... Its amazing they do as well as they do!

We've had great luck for years with the CBR transmission... Our engines have always been used when we got them, and then abused by us. I've inspected 5 or 6 of the transmissions from past cars we've run and they all look pretty damn good. Seems like the dogs on 2nd and 3rd get a bit peened, which can be dressed up once or twice before replacement with a good file.

Don't forget you have a bit of a fuse, called the clutch. I would **hope** that bike OEM's would design to handle everything the clutch can deliver to the input shaft. With a ~500lb or less car, we've had no issues delivering around 70hp to the tires through a stock clutch.

[VFR750R]

We've had tranny problems in the past, mostly associated with bent shifting forks (caused by trying to shift under power)allowing 2 gears to be engaged simultaneously. Additionally, the turbo/supercharged cars can add up to 50% more torque then the stock bike has and transmissions and clutches are really torque limited, not power.

Most blowups are caused by overheating or oil starvation.

[Buckingham]

Also, certain engines don't respond well to being used as a semi-stressed engine. We floated a lot of valves in '03 semi-stressing the engine. IN '04 the problem went away very quickly when we designed the loadpath around, rather than through, the engine.

[Jersey Tom]

I'll say that as far back as I recall (04) we haven't had any engine or transmission grenading at competition with the F4i. Dry sump system in 07 (first year) was a little leaky and had some teething issues, but once it was all figured out kept pressure.

We did spin a journal bearing after 06 competition, as a function of the oil system not having been primed before running our 06 race motor, rebuilt with higher compression pistons. Connecting rod started to loosen up and piston started smacking the valves, etc... engine wasn't too happy about that.

Other than that, only issue I've seen is on our 05 motor we had a bent shift fork, and clutch plates have had light to moderate discoloration after a while. I'd be pretty curious as to how our 07 clutch plates look like after competition, with the whole thing being dry rather than wet (oops!).

To be honest I'm absolutely amazed we haven't had catastrophic failures and major injuries, related to either vehicle and engine stuff or machining/welding/heat treating/oxy-acetylene to 4-5-6-7-8am.

Amazing how your perspective on this stuff changes when you graduate..

[Chris Allbee]

I haven't done the tear down of the motor yet to try and determine the cause of failure yet, turns out i've got a lot of stuff catching up to me that i ignored in the weeks before comp!

However, we went into california knowing that we might have a cooling issue. The plan was if the temp light came on to grab a few extra gears, drop the revs, take the time penalty and finish the race. Well, the pneumatic system heat-soaked and developed a leak. That stroke of luck kept the driver from getting into those higher gears near the middle of the first stint. So, stuck in second we did what any race team would do...try to limp it to the finish. The engine temps continued to climb and the "minor" oiling issue we had became a rather large one at those temps...with the obvious result.

After looking at the price/weight/performance/reliability factors, we're going to implement an Accusump for our current system and if it works keep it for next year. the cost/complexity/weight of a dry sump seems like a lot if the Accusump can do the same job (maintain oil pressure) and be cheaper/lighter/more simple. But testing and time will tell that story and we've only got a scant few months until Detroit next May. Better get started!

[mtg]

You guys did an awesome job, but I think I remember at one point chiming in about the whole pneumatic shifter and clutch idea at one point....<puts on the Waltman hat>.....oh, here it is, have a look:

http://fsae.com/eve/forums/a/tpc/f/125607348/m/53110536...10146731#66110146731 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/53110536731?r=66110146731#66110146731)

[Chris Allbee]

just between you and me, i'd prefer a manual shifter with ignition cut. Our current system is nice and all, but we have had non-stop issues with it except for a brief period of reliability between detroit and cali.

I'm still of the opinion that a well thought out cable paddle shifter (think Stohr DSR) with an ignition cut module would be more than sufficient. I'm one of those people who likes to keep in mind that this car is being driven by relative newbies and that reducing shift times from 350ms for a manual shift to 150ms for a half-decent electro-pneumatic shift is not where the most time can be gained on the track AND keeping in mind the cost and reliability issues....I'm just not terribly convinced that it is the best solution for our car.

[Wesley]

I talked with Chris a bit about the failure and why and what happened - this was all conjecture on the trip home, because we haven't done a teardown yet - but between what he said and what I thought, it came down to putting too many bandaids on the car.

We first ran into the problem with overheating when we developed and tested the wing package on '06. We pushed the wings out some, letting air in between the nose and the wings, but it was just barely enough. In Detroit, we were running pretty thick radiators, and the airflow was marginal - only the cool temps kept it in line.

When we came back and started doing testing, we found out how insufficient the current cooling situation was. We started overheating in minutes, not laps. We swapped the radiators to a thinner core in an attempt to boost airflow through them - with reasonable success. The car kept under 230 on test days, in the Oklahoma heat. But, also, the high Oklahoma humidity probably kept the engine running on the rich side of stoich.

When we got to Cali, our insurance on our cooling system was a 30lb radiator cap - thats 290º F boiling temp! http://fsae.com/groupee_common/emoticons/icon_eek.gif because we knew we may have a problem with it getting warm.

The issue was - we had run the car in higher temps than Cali without overheating with the new radiators, so it seems illogical that the cooling system wasn't keeping up as we started overheating in the first half of enduro.

Now, what ultimately caused the problem first is unknown. But my current conjecture is previous wear from the high temperature (and low oil viscosity) had previously damaged the rod bearing, and it was a time bomb.

Once it spun, heating up and frying the oil, the car couldn't keep cool, and it escalated until the piston stuck in the bore and the wristpin tore free sending the rod sawing through the crank-case. The now (literally) boiling oil shot out onto the header, autoignited, and the rest is on Youtube. http://fsae.com/groupee_common/emoticons/icon_razz.gif

We designed a windage tray - and were running it the whole time - but without accurate pressure logging, we are unsure of pressure dips, and if that played a minor role in the issue.

So, I can definitely say that more thought will go into the cooling system and oil sump - more in the cooling system though, because we never really addressed that issue, other than "that should be good enough."

[John Stimpson]

I've heard of and seen so many damn problems with automated shifting systems that I turn around and run as fast as I can away from them.

A manually operated mechanical shifter with someone thats had the oppurtunity to practice with it for a while is damn hard to beat... And stone reliable.

[John Stimpson]

Wesley: Sounds like a very common tale...

1. Gets hot
2. Spins a rod bearing
3. Chunks a rod

[Wesley]

True. But I can't break things down into bullet points. http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Erich Ohlde]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">A manually operated mechanical shifter with someone thats had the oppurtunity to practice with it for a while is damn hard to beat... And stone reliable. </div></BLOCKQUOTE>

A well developed pneumatic or hydraulic shifting system, like the one on the OU car, will be faster and better.

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by John Stimpson:
I've heard of and seen so many damn problems with automated shifting systems that I turn around and run as fast as I can away from them.

A manually operated mechanical shifter with someone thats had the oppurtunity to practice with it for a while is damn hard to beat... And stone reliable. </div></BLOCKQUOTE>

Lots of cooling system issues in the past. (Heck, OU's problem sounds more cooling related than anything!) Do you turn around and run to an air-cooled engine?

A manual shifter is far from stone reliable; in fact it adds a very unreliable part to the system- the driver. I've heard of many bent forks, bent linkages, etc from drivers being too aggressive. With an automated system, it does the same thing, every time. Same torque on the lever, etc.

At Auburn we failed our electropneumatic system my first year (2000). We then completed 4 straight events without any shifting problems (and 5 more since). In fact I cannot recall a single problem we had with the system in testing either. The system was re-engineered, properly, for 2001 and methods were put into place to ensure it's reliability (such as maintenance and leak checks).

Engineering is a science, if you design something within correct parameters it does not break. No system is inherently unreliable. To say so is not acting as an engineer. 'Unreliable' systems are simply poorly designed.

Of course, simplicity is a good thing, and if you find no case for a more complicated system, then don't use it. The more complicated the system, the more effort needed to create a proper design.

[terra_dactile]

In 2004 we had reliabiltiy issues with the mechnical shifting system prior to the endurance, the push pull cable was routed to the shifter lever at a slight angle and cause serious problems, this was a design error, the reason we changed to a electronic solenoid paddle shifting system for the 2004 Uk event was more to do with the fact that drivers complained it was so tight on track that they would perfer to always have there hands on the steering wheel, the electroinic system sucked because as the battery voltage dropped eventually we could not shift anymore and the solenoid needed special fins and ducking as to not over heat overheat. Since reading the Auburn FSAE section in 2004 Racecar engineering article we have employed a paddle activated electro pneumatic system with no issues what so ever except for buttons that jam in paddle mechanism or leaks in the system because of higher then necesary pressure that passes the limit of the conections.

As Charlie mentioned any system can become reliable if designed at tested properly.

About dry sump we have also employed this etup since 2005 and feel the trick is in baffle positioning, keeping the tank away from the exhaust and locating the over flow conector far from where the oil will be pushed by gravity as the car brakes.

Jude Berthault
ETS FSAE 2003-Current
Team Captain & Vehicle Dynamics Leader

[flavorPacket]

We've had a dry sump since 05 and it wasn't perfect to start, but with time it has become extremely reliable.

[Chris Allbee]

I'm fairly convinced OU's problem was due to heating as well http://fsae.com/groupee_common/emoticons/icon_wink.gif That being said we were also having problems with oiling prior to the endurance race. I'm certain that the engine didn't approve of being overheated and then starved of oil. Given the reliability of these engines (lets face it, the japanese sportbikes are the most reliable) the engine MIGHT have survived even while running at temps climbing towards 250deg if it hadn't been starved of oil in those conditions. I have heard of teams that accomplished this very feat, but they didn't have oiling issues. Not saying that it is a good way to go and I would be tearing down any motor that went through that, but we might have finished the race...Then again, if the thing hadn't been over-heating I KNOW that we would have finished the race.

As far as the shifting business...I'm still on the fence about it. Every time something fails, the knee jerk reaction is to run in the other direction (in this case back towards a manual shifter), but after talking to a few people I'm just a little bit unsure of which direction to proceed. An all-electric shifter would be leak-proof, but heavy and draining on the battery, requiring a bigger battery (or use of capacitors) which would just add more weight. A pneumatic system is lighter, but needs more maintenance and is prone to leaks if not looked after. With a group of volunteers a "hands-off" reliable design such as the electric or manual shifter would seem advantageous, but you might incur a performance penalty in excess weight (electric) or incompetence (manual). The electro-pneumatic would seem to be the performance option, but requires more specialised care, meaning it will probably be one person's specific duty to keep an eye on the system and check it over before and after each run.

Each way has its pros and cons, but if a team were wanting to go the paddle-shifter route, i would probably have to recommend the pneumatic. Dirt-cheap, mechanically and electrically simple in its purest form, and damn fast to boot. Word of advice: remove as many connections as possible, for obvious reasons.

Sorry for the rambling....

[Maverik]

We run manual shifting and through logging our shift times are in the 150 ms range (new driver's or not)... personally that's enough for me to never consider a pneumatic or electric system... short of some crazy f1 setup that shifts in what, 50 ms or less? Also been running dry sump for a couple years, and has worked great for three years. A few problems here and there in development, but with logging we could easily pinpoint the problems and develop a lighter and better system every year.

[fade]

I'm pretty sure an accusump was suggested (well) before competition. http://fsae.com/groupee_common/emoticons/icon_wink.gif http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

[Drew Price]

We at Northwestern are using the 450 single from an '06 Suzuki LT-R450 quad, which has (I believe) a dual pickup dry sump, however since it is from a sport quad, lateral acceleration was a design consideration that went into it's construction that is not seen on Moto-X or street bikes, so we will be sure to report on it's functionality once we are able to adequately put it through it's paces in the fall.

Best,
Drew

[Michael Hart]

For what its worth, we used a dry sump this year for the first time and it seemed to work pretty well. We may have had some issues with intermittent pressure loss during initial testing, but the system didn't experience any catastrophic failures in testing or comp (knock on wood...)

we also have been working on a microprocessor controlled pneumatic shifting mechanism, but it takes a long time to fine tune the timing, especially when the system is pretty much being built from the ground up. We saw some pretty fast shifts, but there were also some missed shifts and we had issues of running out of air after only a dozen or so shifts - no good for enduro...

[Chris Allbee]

Then again Dave you need to speak up and speak to people to actually make a suggestion, not just mumble it into your coffee...

[Alexandre D.]

I've rarely seen an engine fail. Everything upstream and downstream of the engine is much more likely to fail because it's designed by FSAE.
Cooling system is still a big issue. I've seen poor design. When weight obsessed people see a 5lbs assembly just stocking... water... they want to reduce its mass by 50%. Add to that bad assembly, bad bleeding, kinked tubes and all the extra you add 15 minutes before endurance, you have an overheating problem.
The other issue is oiling. Dry sump is definitely not obligatory. You can help a lot with a decent baffle system. Before going dry sump we used a nicely made set of baffle. Pressure would drop during skidpad but it was not an issue for the more engine intensive autocross/endurance. There's a lot of work involved before being able to be as reliable as a baffle system, let alone better.
I saw some blown piston. Most of the time it's due to a failed injector/wiring/ECU. You must be very careful when you work on the fuel lines to not clog your injectors. Some ECU can diagnose shorted/open injectors. The other possible issue is the ignition advance. Some teams runs with crazy timing.

These clutches are cooled by the oil so overheating is not a big issue. Like VFR750R said, clutches are torque limited. It doesn't matter if a bike is lighter. At WOT you produce max torque (not exactly since it's a transient...).
At lower RPM we see as much as 70lbsft of torque (maybe more, the dyno can't hold the engine). This kind of torque is rarely seen on track. Since the engine is always in transient state, the lower RPM is hardly ever used at WOT.

Overall the vast majority of engine failures are not due to the engine. 600cc are in fact a bit too big for turbo car... There's just no market for a 500cc 3 or 4 cyl engine...http://fsae.com/groupee_common/emoticons/icon_frown.gif

[Pete M]

Everything we've done suggests these motors are extremely robust (although i can only vouch for the CBR600F4). We've done some frankly brutal things to them in the past. We've had a few engine failures (we average about one every couple of years), but near as we can figure, they've all been due to mistakes (mainly dumb lubrication things), and all were on the dyno, not in the car.

We've never blown up an engine due to a legitimate pushing of the limit nor have we had one just fail under normal conditions. This is with approximately double stock torque and mixtures that are best described as "very lean". We've also done a fair bit of testing with a pneumatic quickshifter and as far as we know we haven't damaged any transmissions.

I'd wager that pretty much all engine failures in FSAE (at least with 600s) are due to the teams doing dodgy internal work or not properly designing auxiliary systems like cooling and lubrication.

[Welfares]

We've only ever lost one engine, we put a rod through the side of our dyno engine.

Inspection revealed that a nut had come off one of the big bearing cap bolts. I guess someone wasn't using loctite when they put the engine together.

[Poe]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Welfares:
Inspection revealed that a nut had come off one of the big bearing cap bolts. I guess someone wasn't using loctite when they put the engine together. </div></BLOCKQUOTE>

The nut got all the way off the bolt before the engine blew? I've never put loctite on any of the rod fasteners nor the mains and have not yet had a rod punch through the side of the block (4 engines over 3 years - a dyno engine and 3 competition engines).

[Pete M]

Yeah, you really aren't supposed to be loctiting any of that stuff. If you follow the directions in the manual and use a torque wrench, it won't come off. There's a few bolts retaining stuff like the cam chain tensioner that are supposed to be loctited, but that's all (a least on a CBR).

[Mechanicaldan]

In my opinion, dry sump systems are usually added so that the engine can be run really low in the chassis, but you will add weight with the oil tank, lines, and scavange pumps. As mentioned, a baffled oil pan is another option. Iowa State has been running this similar design for 3 years on a ZX-6R without a problem.
http://sae.stuorg.iastate.edu/albums/album66/IMG_1121.sized.jpg

I would say most tranny problems are caused by an inexperienced driver (someone with less than a 100 hours of seat time).

Some of the newer engines are coming with slipper clutches from the factory which should help with tranny life in respect to abuse from the additional traction and driveline shock of downshifting. This won't help with upshift abuse.

[VFR750R]

Agreed on the Loctite, no loctite on fasteners critcal for bearing fit, mostly because there is a specific lube the factory requires to get the correct clamp load at the recommended torque. ie. mains, rods, cam caps, head studs

My second rule of thumb; no loctite on anything bigger then 1/4-20, or 6mm for metric stuff.

[murpia]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mechanicaldan:
In my opinion, dry sump systems are usually added so that the engine can be run really low in the chassis, but you will add weight with the oil tank, lines, and scavange pumps. As mentioned, a baffled oil pan is another option. Iowa State has been running this similar design for 3 years on a ZX-6R without a problem.
http://sae.stuorg.iastate.edu/albums/album66/IMG_1121.sized.jpg </div></BLOCKQUOTE>

That looks quite a low sump height, for a wet sump. Can you comment on the oil capacity?

Would other teams mind posting images of wet sump baffling schemes that work well? I'm sure helping prevent teams lunching engines is within the competition spirit.

Regards, Ian

[Mark TMV]

Our wet sump was just a 2" deep welded aluminum box with multiple baffles welded in - very easy and cheap. We also extended the oil pickup tube all the way to the bottom of the sump. Had not absolutely no issues with this setup and don't really see a need to move to a dry-sump now.

Sorry I don't have any pics right now

[murpia]

Thanks for the info guys.

Anyone know the rough oil capacity of the engine when running? I.e. if you fill the sump with say 4 litres from empty, how much remains in the sump when running (once the pressure relief valve opens I guess)?

I'm thinking that this would be the ideal capacity for a baffled sump, with a 'lid' on it to keep the oil from climbing the walls uner lateral G.

Regards, Ian

[Mike Hart]

Well. I thought I should perhaps add my 2 cents worth. As many of you will have seen at FSG....we blew an engine :P We're fairly sure it wasn't water cooling related as our temps never got critical. We'd be surprised if it was oil starvation too as we've not had problems before using the same baffled sump design (although we didn't have an oil pressure sensor on our 07 car).

There is a possibilty that it was just engine failure plain and simple though. The one we ran at comp was off a dropped bike, had a cracked cam cover and no other engine covers! It had been fine in testing and UK comp (completing around 2 endurances in distance) but it wouldn't surprise me if a bolt was loose on the conrod or some such similar issue.

The other possibility (which is possibly the most likely) is the oil cooling capacity. The R6 runs a heat exchanger using the water to take heat from the oil. Since the oil started boiling before the water we think it's simply a case that the exchanger just doesn't have the capacity to remove heat fast enough from the oil if the water is already hot. Remember that the air flow through an SAE radiator is considerably less than it would be on the bike and you're also continually running at high revs. How many road bikes do you see driving round in 1st and 2nd gear on the limiter at 10-40mph?!

With regards cooling design, another major problem a lot of teams may encounter is the rather weak ability of the water pump to pump water! The pump on the R6 simply must be the lowest point in the cooling system otherwise it will really struggle. We have a huge heat exchanger on our dyno which is about 300mm lower than the engine and the R6 water pump just couldn't shift the water properly....hence we now have a massive central heating pump doing its job!

But in my opinion probably more than half of engine blow ups in FSAE are caused by cooling. The low speeds and high revs are a great combination for overheating.