[ab954]

oops i must have missed some of these other posts, sorry! I see that this horse is long since dead!

[TR11]

Originally Posted by Sti_Time

Slowride, I could have written a 2000 word essay for you on the subject, however just as is the case with bitabur and dmpi, each side believes 100% they are correct, just as I'm sure you do, and will remain unconvinced. That is why I brought up the reference material, that would settle the matter and leave no dought for anyone.

8)

I dont have an opinion on whether your right or wrong but only that you argue your point with such arrogance. A 2000 word essay wouldnt be needed to prove slowride wrong. Just a basic one line physics or thermodynamic theory that your using to disprove would be fine as i would like to know the answer as well. And dont bother posting back to me for i am not about get into a battle of wits with a half armed man. :roll:

[Ender2664]

I have a simple question, and i dont know if anyone can answer it. What psi is the bottom end of the STI rated for.

[Sti_Time]

TR11 Its ok, just because you did so poorly in school, and you were always held back after class because you could not keep up with the other kids doesn't mean anything. Really it doesn't...

Now lets see, in that one paragraph you manage to contradict yourself completely. First you say you want to know the answer in one line, why I believe something is wrong. Then you say not to bother posting back. So which is it? Not seeking to get into a battle of "wits" just clarification.

:roll:

I say better to be half armed, than being a half wit...don't you agree Mr. TR11?

Sorry to the mods in advance for this, but this guy running his mouth, was just easy pickings.

[salisburyv]

really can we be civilized and not bash... that's why i check this site....dont insult....very bad manners

[roadrnr37]

Don't be to quick to judge there INVISI.. his statemetns are not all that false. However he did make some rather important points.
PV=nRT is the ideal gas law, yes this is ideal, however you ahve to take into acount that velocity of turbine, friction of bearings, and disipation of heat in a larger turbo can make all the difference.
bitabur = pointed several of these out. Don't alsway jump to conclusions. Slowride is learning and that is all that we want here.... IF we all knew everything then we would not have to have this forum. I have designed engines and done thousands of hours building and testing them and I still have more to learn. Smokey once said that even through all his endevours he would know only a fraction of the knowledge to be learned. And he is the father of the modern Turbo/supercharger era. And the scary part is he had know idea that the EBC would be a possiblility. So let us all be more sensative, and also before we make blanket statements, we need to consider the audience we are writing to.

Sorry to ramble, but i just think the more we cooperate and have constructive argumetns the more we can get accomplished AKA = go faster and at the same time keep our cars running

[bitabur]

So could you give us your take on this than? It seems like you might know a little more about this from the experimental side than we do - I know that all of my comments are purely theoretical.

[Singletrack]

Originally Posted by bitabur

However, I think a smaller turbo would be spinning much faster to achieve equal boost, and therefore probably be creating greater friction, and therefore generating more heat, some of which is getting passed into the air it is boosting..... that's just a guess though.

Exactly. Smaller turbo at a given PSI produces higher IAT than a larger one. Hotter air = less mass.

-st

[Singletrack]

Originally Posted by bahlool

hey guys i was wondering how much boost my stock internal engine can handle? i've heard my engine cant handle more than 20 psi with stock enternal and i thought it should handle more than 25.. pls let me know thx

Well I know that XT6wagon is running 23PSI right now per his post on NASIOC. He hasn't been running that long though.

-st

[roadrnr37]

Theory can only get you so far. But it does come in handy. let's assume for a moment that all things are equal, Fuel, Air mass, and combustions speed. So we take the laws of limits in to account. We look at a small turbo, and let it spin fast enough to create the boost we want. So then we take a "limit" a really small turbo, as it speeds up and the compressor side has to spin at a astronomical rate in order to create the boost at a given air mass/CFM. The sure speed would increase the air temp by a astronomical rate due to air/ blade friction, Just like the black bird (SR71) as it sails throught the atmosphere. Friction here is the enemy. However we can also look at the oposite limit and see that the relly large turbo would be worthless becasue the engine would have to be spinning so fast to create enough force to drive it.
That said here ends theorty and thus begins fact (or fact to me anyway)
On large applications, scuh as 18 wheelers the turbo is large and very effivient but does not have to spool up fast nor does it need to produce high boost pressure (relative). But we want speed so we want a turbo that is small enought that we can spin it, but large enough that it can keep up the cfm without having to spin it so fast that is creates eccessive heat. Now there are theorys for calulting this, and they get you in the ball park, but trial and error are the only true factor. IN our case, the rubo could be a bit larger, as long as you opened up your exhaust and let the flow rate increase to keep it spoling at a low rpm. But temp, as long as you are staying within reason, will be close. the larger turbo will be a tad cooler, as long as everyhting else is egual. Yes the compression of the air will produce some heat, and according to the odeal gas law it will be the same heat as with a smaller one, but velocity = friction so our total heat will be decreased with a larger turbo, and in all essence it will have to "work" that is as long as it is not too large it will take less "pressure' from the engine. One thinsg we have to remember is that backpressure at the head is not a good things. I knwo everyone think turbos are great because they need no power to run them, but you do use a little power to run them, just that the loss of power is not noticicble because before the true loss is felt in the vehicle, the turbo has spooled and is helping create more power. AKA there is a reason the top fuel guys run open headers.

I hope this cleared a few things up. Sorry about the typig, it s early here in sac,ca.

[roadrnr37]

As for the rating on the STI, i think that is always and naswered question. I run my boat to 25 PSI and it has a Small block chevy engine. We ran the maserati up to 22 or so and had no problems, but we woudl not keep it on this seting for very long. The only way to know is to spin it till it hurts..... that is the fun part. but in reality if you want a good reliable car with a long life, you might consider staying under the 19 or so range. One other thing with our Boxer engines, the bottom end does not have to be as well built as one might expect. because of the geometry the engien applied pressure to itself thus not wanting to throw thinsg out side of it angular momentum, AKA thrwo a rod clear across the room... hee hee been there. Hwever bearing stress is where you will fail. I have not looked into and aftermarket bearings yet as my STI is only 823 miles old. Nice and young, god she is fast. However if you want to beef it up o would suppose there are bearing companies out there whom either make the bearings, or will make them for you. Stick to the normal, 10-15% over the stock is very good and will get you almost everything you want. Other things can be done other than pushing the PSI envelope.


Don Biery

[qbbraveheart]

can the stock ECU sustain 16.5psi daily???...when i say stock ecu i mean will it see the increase in boost and adjust accordingly??? or would one have to help it sustain that increased boost pressure by adding the neccesary upgrades???

ive read over on some other forums that people are cranking up their EBC's to 16.5psi

[Singletrack]

Originally Posted by qbbraveheart

can the stock ECU sustain 16.5psi daily???...when i say stock ecu i mean will it see the increase in boost and adjust accordingly??? or would one have to help it sustain that increased boost pressure by adding the neccesary upgrades???

ive read over on some other forums that people are cranking up their EBC's to 16.5psi

I think it will attempt to adjust up to 17PSI or so and then you will throw codes for a wastegate malfunction. That value might be a touch higher and is what people typically refer to as "fuel cut" or "boost cut". You would need to look at the A/F, IDC, and fuel trim values.

-st