Greetings fellow zitizens.

Alright so I got a friend who races and builds Supras for a living. He knows a ton about FI and engines in general, and has told me that if I intend to keep the car long, and put FI on it, I should invest in rebuilding the engine internals.

Now I'm not exactly familiar with the entire process of engine rebuilding and what purpose each step has, but I do know that it's very expensive...

My questions are the following:

1) Other than letting me run higher boost, how does rebuilding internals make the engine last longer ? I mean, say after 150k miles... would a rebuilt engine still be going strong or would you have to replace it anyway ?

2) Can someone familiar with each process give me a summary of what they do? i.e - sleeving, boring, pistons & rods, etc..

Thanks =)

 

I should also add that I just spoke with him and he thinks it's crazy for us to be running 8psi+ on an engine with such high compression. He highly recommends putting lower-compression stronger pistons & rods into the engine, allowing for much higher boost and engine longevity.

What do you guys think of that ?

 

I think I'm going to grow bored of this car before the engine blows.

--Steve

 

Yeah that might be true, but it's always good to have a solid engine to resell.

 

I plan on keeping my car forever and if the motor goes then I will replace it with a 600rwhp motor along with what ever else i might need.

 

I have to agree. Really not worth dumping that much money into. Though I have spent quite a bit so far

 

are there z (or g??) crate motor packages available yet??

easiest and best solution, IMO

 

Forged internals WILL last longer if you go F/I. Cast internals are not designed for the long-term us of F/I, and the higher temps and cylinder pressures created. Forged low-comp interals will resist detonation better, and be MUCH stronger. The stock rods are about the thickness of my index finger.....long and thin...not good for high HP applications.


Regarding the costs of going forged. The biggest piece is the labor involved. Some people would recommend sleeving, if you plan on running more than 500-600rwhp.

 

I think he's right. My 91MR2 Turbo had 8.8:1 CR with 7psi and intercooler from the factory. I idled it for 2 minutes before shutting it down after a fast run. Yes, I know turbo timers were available, but I never bought one because I didn't mind the cooldown time. CR over 10 psi is risky no matter how good your intercooler is or the rest of your engine. If you noticed, Srtillen brought out a SC with 5 psi first, and will increase it only after the addition of an intercooler. If you turn up the boost, better bulid up your engine and lower the CR.

 

You will not increase the life of your engine just by putting forged internals in it...all other variables equal. The forged internals allow you to run high boost levels.

 

On boosted motors, what are generally the first parts to go?

 

Anything can go first. I don't this question can accurately be answered. It could be the rings, pistons, or rods....flip a coin. If I was a betting man, I'd say the pistons.

 

Logically i'd have to go with connecting rods, because they support the brunt of the explosive force of the combustion of the fuel/air, and must also support the reciprocating weight of the piston as it slings around at a cool 6600rpm. After that i'd say pistons, because they are directly exposed to the explosions in the cylinders, and are prone to be baked or coated with carbon from excessive lean/rich conditions. Then after that piston rings, and so on and so forth.

 

my bet is on the head gasket under high boost first, but as far as internals it would likely be the con rods. the pistons are not too shabby and the crank is forged.

 

You sure it wont prolong normal longevity ? My friend said it would...

 

Not longevity, unless you overboost the stock internals. If you overboost the stock internals, your engine blows fast... so longevity might be a matter of blowing your engine vs. not blowing your engine.

All things being equal, no, your engine will not last longer.

 

no matter what if you increase the power output of the engine you will shorten its life. there is no way around this, however building internals for boost will prevent early catastrophic failure like blowing a piston through your block. but if you increase the power it will put more stress on everything. i would not expect even a fully built vq with 450 whp to last 60000 miles before needing a rebuild, but 60k is much better than 4k by any measure.

 

When you keep the other variables equal, just going to forged parts will not increase life of the motor. For example, if your car is running great at 8psi, it will keep running like that for a long time.

If you run into detonation because and injector gets clogged or you have someone tune your car poorly, you will blow the motor regardless of what internals you have. Detonation will destroy any type of piston, period.

If you have no plans of running power above what the motor is safely handling at the current time, then upgrading to forged parts is a waste. If you plan on running more boost, you may exceed what the stock parts can safely handle.

One thing to keep in mind, stock parts can handle ALOT of power but you MUST make sure the tune up is correct.

 

What is the motor safely handling at the current time ? I mean I know people are running 8psi for 3+ months... but how is that necessarily safe ? I'd probably be happy with 400rwhp.

 

With either forged or cast internals there are no guarantees with FI. Either set-up can blow up just the same. With the forged internals you have more of a safety net if you're tuning is off. That margin for error is not there on cast internals.