Ok fellas!

I have been doing a TON of research and I need some experienced people to fill in the blanks. I want to put together a chart of boost levels and what can/will fail. Here goes...

19.5psi - Stock
20.5psi/22psi - stock fuel pump limit
26psi - stock headstuds limit
35psi - stock internals limit
60psi - stock block limit

I understand that drivetrain (tranny/diff/axle/driveshaft) failure will be reached with different levels of boost, but the point of this thread is to list failure rates on ENGINE and associated componants.

So, please correct the chart above, add to or modify. I would prefer responses from experienced engine people, not the bench mechanic experts. Lets keep it to the facts.

Questions I have....
- Limitations on stock fuel pressure regulater / stock fuel rail
- Limitations of stock injectors (550cc)
- Limitations on stock head gasket
- Limitations on internals (failure rate for piston rings/con rods/crankshaft)

Please list what works and why, with examples if possible.

Thanks!

-Vince

 

Ttt, for a good thread

 

To give personal experience for each:

The fuel rail and FPR upgrades will allow you to squeeze more fuel out of the existing system. You will be able to run more fuel at a lower IDC. i.e. If you're running 90% IDC with stock rail and FPR you can upgrade them and then be able to run a lower IDC without having to upgrade the pump past a high flow 255lph

The stock injectors will run out of steam at the ~320hp mark with an 255lph pump. While I was getting my car tuned once we hit the ~320hp mark I was running low to mid 90% IDC at WOT. YMMV but when making good power (without meth/alky inj) you will need to upgrade to keep you injectors from constantly being open.

You don't hear too much on the boads of failed head gaskets due to the head not lifting as much as other turbo cars (I come from a 240sx with SR20DET and it was an issue with the stock paper HG)

The rods are forged stock and the crank is very strong. You will spin a bearing (crank or rod) before you bend a rod or explode a crank. The pistons are up for debate and there have been plenty cracked pistons but a lot that I read about are due to meth/alky pumps failing.

Again, these are from my personal experience.

 

Their is no chart that can be made. With a lot of detonation I could blow the hell out of your stock car at stock boost. With just a little preignition I could also blow the hell out of your stock block.

With good internals you can easilly run more than 60psi on the stock block. Especially if your head flows like a straw.

 

I cracked my stock pistons at only 19psi. Mods were...TBE, APS BOV, AEM EMS..speed density, and K&N coner filter.

 

Yeah, agree with Dan. You're making the mistake of taking boost in a vaccuum and thinking it's the only factor that matters. I can run 26psi with alky injection on stock cams and put less stress on the injectors than with 22psi on straight pump gas and cams/manifold/o2. That's just one example. Tuning, fuel, and mod combos play a big part in how much boost can be run on a given fuel setup.

Btw, I went 12.22@111 @ 24psi on my stock fuel pump and a few basic mods using a mix of 104/93oct. Others have gone higher on the stock fuel pump. Not saying it's recommended, but 22psi is by no means a limit for the stock fuel pump, nor is 26psi the limit for stock head bolts. In fact, although we always recommend doing them on Evos when installing cams or when running 25+ psi, the instances of blown head gaskets are very rare.

 

My goal for this thread is to give a safe recommendation on what limits we can/will encounter. I assume most of us drive our Evo's every day and want to modify safely.

This thread assumes proper engine management and supporting mods, so I will pose the question another way...

Think of this as an "If then / what" question.
IE. If your fuel pump is upgraded, then what is next to fail and at what boost?
IE. If your headstuds are upgraded, then what is next to fail and at what boost is risky?

Warrtalon <--- I respect your input and think you have the most to contribute here. I / we all have stories of things we can get away with (running crazy timing, extreme levels of boost) but my goal is to provide safe information for someone to follow. I want to reduce the chances of any of us experiencing significant failure that we were NOT expecting. I personally plan a safe and reliable buildup for my ride, but I am stumped by the confusing info on this forum. That is why I ask you to provide facts. You know more than I do and I look forward to your response.

-Vince

 

I am on the edge right now on trying to decide whether or not to upgrade my fuel pump and/or injectors before attempting to run 23-24psi. I have heard many dissimilar opinions from different people on the limitations of the stock injectors and stock fuel pump.

Has anyone had a fuel pump fail or injectors get stuck open?

 

do the pump man, its 100$ mine as well jsut do it. If your on stock turbo, you shouldnt need injectors unless your DC is maxxed out, like your runnin 30 psi on meth or sumthin

 

Just out of curiousity...what would happen if I left my stock fuel pump in, turned my boost up, and did exceed the flow of the stock pump? Would the pump break, or would the afr just lean out?

 

You would run out of fuel (go lean) and your ecu would rob you of what little timing you are already allowed^^^^Your pump would not break. The motor will just be starved of the fuel it needs.

 

Bump im running a 35r and would like to know if im going to get 4g63 Soup for Dinner when I hit 29 psi.

 

Boost didn't crack your pistons, the detonation/knock did it.

 

As long as you don't mess with your low octane fuel and low octane ignition tables, won't the ecu default to those when knock is present to save your engine?

 

Low octane fuel??? Doesn't it say premium gasoline only on the gas cap? When knock is present the ecu will try to retard the timing to lessen the detonation, but that doesn't mean it is a guarantee that your engine won't blow.

I'd like to note that just because someone else is running 24psi on a stock evo does not mean your car can do it also without any problems.