OK Bryant, here is your own thread highlighting the entire build process of your Monster project. I am already behind because your engine is out of the car and completely disassembled. I will go into the performance aspects of the build after we highlight the process up until this point. We have some very interesting information to share about your engine when we took it apart and inspected it.

Since 2002, when we first began building these engines, we have always stressed the importance of strengthening the internals. There are many companies that are pushing these engines well beyond their limits without internals, however it has always been our stance that beyond about 700 HP, it is not a matter of "if" the engine will fail but when it will fail.

The GT1 engine case and bottom end components are very strong to a certain point. The weakest link in the bottom of these engines is the connecting rods. Many companies want to believe / want the enthusiast to believe that these rods are very strong and bulletproof. The facts are that this is the same connecting rod that was developed for the 993TT. This connecting rod is installed in the 996TT, GT2, X50 as well as the 997TT engines. These rods were the weak link back in 1996 when we were pushing the envelope of that engine and they continue to be the weak link in 2009.

A fair amount of the engines that we disassemble prove this weakness. Some engines, like S-351's are the lucky ones where the rods bend. The next step is the cracked rods, like S-351's. The final destruction comes when the rod breaks and punches a hole in the side of the engine case which at that point completely destroys the bottom end of the engine. Much of the fatigue comes from high power and these rods cannot withstand sustained forces against them without bending. They can last for a while if the engine is pushed only for a few short acceleration runs here and there but will never last on a race track or at sustained high loads where consistent heat and pressure are maintained.

There are very few enthusiasts that want to spend $10K-$15K to build the bottom end of their engine for strength purposes. Additionally, this expense is harder to justify when the build only addresses the strengthening aspect of the engine and the performance gain from this procedure is minimal. However, as I mention above, it is not a matter of "if" but "when" the engine will fail and the damage caused by one of these failures is much more than the cost to prevent the failure from happening in the first place.

S-351 must be a lucky guy because we have never seen a rod cracked like this. All of the engines we have seen like this, the rods are either bent or broken. We have never removed a rod that was bent and cracked. It is a good thing that we didn’t dyno the car before we removed the engine. I am sure that a couple of pulls and the rod would have broken and caused some major damage.

Here are some pictures of the car, engine being disassembled and the connecting rods.

 

Holy cow! The rod was a ticking time bomb. Thanks for sharing.

Best of luck to S-351 and Evoms. Can't wait to see the final numbers when project is complete.

 

Wow - bent and craked - shows the limits of this engine.

Congrats Bryant and good luck.

Jag

 

Well, glad to see someone doing the right thing before it pops....
that was close...
mark

 

What were the previous mods and power level when it bent/cracked?

 

i think he was running alpha gt30rs and dynoed 680 rwhp... things that make you go hhhmmm... especially when some recent builds are north of 800 rwhp... I hope we do not loose more motors anytime soon...

 

If I'm not mistaking a very low mileage car as well.

Good Luck with the build!!!

 

Perfect timing, that rod was just about to let go. What power level was S-351 at?

 

Exactly - Its hard to believe that some tuners are building these cars on stock motors with that much power. Its cheaper to go in a change rods before a rod goes through the cases.

 

680, thanks Mark.

 

no surprise at all. I have been told to keep power below 640 to the wheels for a long time. Thank god this was found beforehand.

 

I respect this and your experience, but is it not possible to conceivably believe the generally accepted "safe limit" can move up over the year due to more experience building this motor, learning new "tricks" (for lack of a better word), tuning, etc.?

I do not know much about the Supra motor/block but I see a lot of people who are knowledgeable in that arena cite when it was "conventional wisdom" that that stock block was only good for 500 or so hp, but after many years of trial and error, it has been safely run up to 800-900 hp on a consistent basis. Again, I do not have first hand knowledge of this but I see it cited by purportedly reputably sources often.

Can this advancement not be applied to the Porsche GT1 motor? It seems more are doing it these days at a higher clip as Markski suggested, but time will only tell if they last and how long they do.

 

again it all depends on what you are after. if you are looking at some 1/4 mile runs at those power levels fine, but in the long run that kind of power is detrimental. Supra engines are relatively cheap, and that is more of a reason for high power than durability. supra engines blow up to

 

I hear what you are saying but one cannot deny the fact that the same connecting rod that has been used for 13 years and has been the weak link on engines making north of 700-750 HP. This is a known problem for those who build and have build alot of these engines. Sure they can withstand more than this power level but one mechanical over-rev or one day at the track and I am sure that more of these engines would fail if pushed. One dyno run or 20 for that matter and a couple of 60-130 runs and a few 1/4 mile passes probabaly will not cause the failure at high power levels. It all depends on how the car is driven and how much risk someone is willing to take. The scary part is S-351's engine ran good and made no noises to indicate that it was one hard pull from letting go.

 

Don't quote me but I think the car has about 14K miles on it. It had a Speed Gallery 700 HP upgrade on it before we worked on it. S-351, the owner can provide the details. Here is a brief history from what I know:

- Car is driven hard and was producing ~ 700 HP for a few years
- I met Bryant through LuisGT3 this summer and we discussed an engine build
- Bryant wanted to push the engine further before we started the big project
- I advised him the pitfalls of pushing this engine beyond the 700 HP mark and he was well aware of the potential damage that could occur
- He agreed to build the engine with us but before we started the project, he wanted to push his stock engine further.
- It went against my better judgment to push it, but since we already agreed to build the engine I went with it. Bryant was well aware of the consequences and was in no way holding me liable, so I was more curious than anything else.
- We installed GT30 turbos, our intercoolers, our headers, our complete fuel system and I flew to MN to tune the car. We made some good power but, I had a feeling that it would be short lived - especially since I knew that this car was no garage queen and he would be pushing it hard.
- Fast forward to last week - my theories and years of experience with these engines proved correct once again and I am glad it was not the worst case scenario.