Stock internal, Max reliable HP!

[NewTurboTuner]

I know this is an age old debated dealiyo
But I wanted to share something I learned today.

So I was at Pina Motorsports today talking to Andre about my future set-up possibilities. We were talking about what it would take to make my goal of... 500+awhp, pump gas turbo only, street/strip car. I told him that I'd like to get 400awhp out of my rebuild 2.0l, until I have the $$ to build a race motor. That lead us back to the age old topic of: "What can a stock motor hold up too?" Keep in mind that we're talking about a street car.

Here's the scenario... You want 400whp from your stock block. You take all the steps to do everything right. The Turbo, Air, Fuel, & Tuning are all done right. The car is running awesome at 400whp. The car's cast internal parts seem to hold up fine, and there doesn't seem to be any problems at all.
~The next question is: How long will everything hold up, and stay that way? or Why wouldn't it hold up? Basically it comes down too the strength, and reliability of the parts ...the ability of the internal part's to hold their shape and last. It doesn't matter if you have a smooth running motor and everything is done correctly. The parts will still take stress with all of that HP, even if it's smooth HP. Stress causes stretching, warping, and deformation. Those are all enemies of reliability. Once a part reaches its stress limit, it loses shape and usually breaks.
~OK so... In our case we are going to measure stress levels in HP. And the goal is 400awhp (450+crankHP). How long will the stock internal motors take that much stress before it becomes weak, and is stressed too the limit of failure? Also; Which vital parts are the weakest link?. (The entire engine's strength depends on the weakest link) The conclusion that Andre has come up with over the years... is that the stock cast internal are usually OK, but the bolt/nuts that hold it all together are the weakest link. And even if you take all the proper steps to insure your High HP stock motor is build right.... The bolt's that hold the motor together are taking too much stress at 450+ crankHP. The bolts will stretch, and take everything out of balance, and you'll end up with a blow motor.

Before today I never though about the bolts failing before the cranks or rods would.... but considering the strength of the cast internals.... it makes sense that it would happen, even if everything else is done right.

I think the stock internal Max HP consensus was...
350crankHP is fine
400crankHP is OK
450crankHP is pushing it
450+crankHP is asking for trouble.

So I asked... What about holding the stock internals together with ARP studs?
That would help the motors reliability, but it doesn't make sense for me to do that, I'll just wait for the race motor. It might be worth a try to someone who's in the correct position to try it??? (Hey for you smart azzes out there. Note): I'm not saying the stock bolts are the only thing that break, or are the 1st thing that will break. I know people have made way more HP on a stock motor. I'm just saying (for a street car) even if everything was built perfectly, a stock motor wouldn't hold 450+crankHP for too long.

Anyway...
maybe this info will help other decide how high they want to take their stock motors

L8tr!
~SteveB

 

[nightspeed87]

good write up... Someone is bound to challenge this though since yea there is a lot of smart asses....

I dont plan on more than 350 whp even if I could make more, thats my limit, and my internals are all cryotreated so I probably have a slightly higher thresh hold in durability, but this is a good thought for those who think a motor being able to handle 400whp is the same thing as a motor being able to live long with 400whp....

 

[Black Venom]

I also agree on this being a good write up, Question I have is on one of the only things you left open for speculation. What is too long? Are we saying a 450crankHP motor could last 15K miles? And a 450+crankHP motor could last 8K miles?

 

[JLangevin]

... and to add onto that, its not how many miles - its how many ABUSED miles. There is "racing occasionaly" and there is "The Grocery Getter 500" - Some people (Like myself) cant keep their foot off the gas pedal. If Im going forward, it has to be as fast as possible and Ive paid the price in repairs and gas costs.

What I am adding to all of this is a stock engine "capable" of even 500whp will last forever, if never ran on the edge... but a 400hp stock 4g63 ran like a race car EVERYWHERE it goes, may not last a month.

Folks, its all about durability vs abuse. Weve all seen the videos of DSMrs blowing up on the dyno etc, may not have EVER happened on the road, but the load caused the stress, etc. There are a lot of other factors besides the engine internals itself and tuning... you mentioned

-Proper Tuning
-Turbo Timed
-Proper injectors
-Intercoolers
-etc

But what about cooling? I have a local DSMr who was running consistant 11.4 @ 125 in 104* SoCal heat, and even with Fluidine Radiatior, upgraded fans, thermostat, fan switches, etc... was still battling overheating problems... Do you see what it is I am saying? Everyone will be different. He runs every weekend he can, and has a stock engine except cams... His latest dyno put 530awhp. Everyones results wont be the same.

 

[GVR4592]

The stock hardware has always been the weak link, mainly the rod bolts. Of course that limit isn't usually reached until somewhere around 500-550whp on a 1g. Most failures are due to poor tuning, but 10-15 year old rod bolts aren't helping the situation any. You could spend some time and polish the rods, then have them shotpeened. It seems counterproductive to polish them just to shot peen them, but polishing eliminates stress risers that form in the casting flash. You could gain some additional strength this way, but the cost is probably similar to buying a set of Scat or Eagle rods.

Your horsepower estimates are probably off by about 100 hp, but other than that the rest makes sense. There are guys that have made over 550whp on bone stock 1g bottom ends, which is over 600 crank horsepower.

 

[NewTurboTuner]

"The Grocery Getter 500"
hah... That use to be me. I just simply couldn't help it... like it wasn't even my choice... I just had too
But after years of paying to play... I've learned just how expensive it really is to play.

I only drive two different ways now.
80% Driving Ms. Daisy
20% Drive it like ya stole it!

Seriously... If I'm not going WOT I drive so slow. I never let the boost get over 5psi to save gas.
Then when the ricers/stangs start to phuck with me... W!O!T!!!!
All I see is WTF in the rear view .......I love it!



The reason I said 450+ Crank HP was about the limit ....is because I was talking about the reliability side of things... and for reliability 450hp is about the end of the road. It sucks worrying every time you go WOT; thinking something might break if you do go WOT. Up until today I was shooting for 400awhp (thats maybe 470 crank HP) with my stock 2L. I know that is totally do-able... but it wouldn't be too reliable for a street car, and I just don't want to worry about breaking something every time I go WOT. I want to be able to go WOT, and Not have to worry about anything. So I guess I'll shoot for 360awhp (about 430 crank HP) now. I know that's still pushing it for a stock block street car, but I think I can keep it together until I get a race motor built.