Built Engine Max Boost
 

I will be building up my miata in the next week with the belfab kit. Roughly 9:1 compression, rods, valvetrain, EXintake mod, Cam gear, etc... I know on the stock block 12psi is safeish, 15psi is pushing it, and 18psi is a ticking time bomb. When it comes to built motors I can find less input on what they handle.

So with all supporting mods and with a good tune, what can a typical built bottom end handle. Remember this is roughly I know all about different turbos, timing, intake flow, transmision, differential, etc... Thanks

You can run more than 18psi with built motor. But transmission becomes a issue after 250whp.

With forged pistons and forged rods, the limit is no longer the engine. The drivetrain behind it becomes the limiting factor.

I am well aware of the drivetrain issues with these cars. I have owned another miata and have built many a cars. So thank you for that information but my question still is how much can the ENGINE HANDLE?

Given how little sample data there is it'd be terribly irresponsible just to throw out some approximate number.

Maybe you should go talk to that dude who built the eliminator miata who's running ~500+hp on his 1.8

Who knows? There is no definitive answer. A few have done 400, 500, and 600whp setups with built engines. Those are not necessarily the MAX ENGINE HANDLE per se. These are just numbers that have been put down.

Thanks for the info. Anybody else have any experience/input. Although I think the turbo I will choose will limit me since I don't want to sacrifice too much lag. Although I could always add a small nitrous shot:firedevil

Lots of people do. Learn to use the damn search function and maybe you'll find their input too.

Maybe I have searched and seen that they do. WTF did it have to with my thread and your unnecessary rudeness. Which when searching I have found ALOT of.

Asking how much boost a motor can handle is not a very good qurstion. 15 psi on my 2854 is a hell of alot different than 15 psi on a 3071. Tell us what turbo you plan to use and then you might get a more accurate answer. Although you could just search.
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I haven't decided fully on turbo yet so thats why I am asking a general idea. And I have done a search and there is little information on the breaking point due to limitations of engine.

41lbs

Chucky, your questions are weak, and very noobish. You've already had some of your post deleted because they were crap. This is borderline.

In a sense, you are being rude posting questions that can be answered (indirectly) by searching. So expect some hazing. The fact that you put "max boost" in your title shows your lack of understanding.

If you are anywhat worried about lag, then you're not worried about how much power a built engine can take.

I rest my case.

Max boost is a very scientific term. They are not weak or noobish. Hell one minute after I started this thread another member with thousands of posts asked the same question.

I have only been rude when people were rude to me first. I have thanked people when the gave good info and told people who wasted my time to piss off.

There is a balance between power and lag. I need to know the max boost a engine can handle so that I can compare what turbo can put out that much and see how much it lags. Then go down the ladder untill I find a happy medium. Wow don't know if this forum is for me at all!

Also if you find me 5 threads were they talked about the limitations of the block with a fully built bottom-end I will admit i'm wrong. It the one started 1 minute after mine doesn't count.

This is where your main problem lies. As has been said in this thread already. 15psi from a gt2554 is much different than say, a gt42r. Therefore, a number of max boost is irrelevant unless you had already chosen a turbo.

Wow that is so not true. If someone tells you he was running a gt2860 at 25psi and it he bent a rod you can tell that if you run a gt30r at 22psi the flow will be the same so the limitation is the similar. Also at the beginning I said I knew all this and this was a rough estimate.

Wrong. On several accounts. You need to respect all the senior members of this forum, even the ones that are being rude to you. Underneath their rudeness is good advice. Regardless of what you think, they're right. 6 months from now you'll look back at this thread and laugh, and realize what a dick you were and how you should have taken Sav's and other "haters" post more seriously.

Also wrong about max boost. Boost :ne: power. Boost is a measure or restriction. When selecting a turbocharger for an application, you first decide on a power goal, then look at various turbos that will get you to that power goal.

AGAIN, IF YOU'D SEARCH ALREADY YOU"LL FIND ALL THIS INFO IN THE FORUMS FAQ! HINT HINT!

And if you'll look at the guy that asked "the same question" you'll see his title says POWER, not boost.

yes max boost is a scientific term but for what. my build motor can take everything my 2854 can throw at it and not break a sweat (providing a good tune). What psi that is I have no idea. Like I said earlier 15 psi on a 2554 is worlds different than 15 psi on a 3071.


Lets try this. What are your goals with the car? What do you plan to use it for? How much money do you have?
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No just because I am new to this forum does not mean they can be rude! Power varies way to much to be a comparison. Boost is more accurate because it accurately measures the maxium pressure that the engine can handle.

A car can have 500hp and 400hp but be only running 30psi. Both of which would blowup at that same psi but not hp.

Goal=Get the most power out of the engine which would require running MAX BOOST But first I need to what the MAX BOOST is so that I can see if the turbo will be to large for my taste.

Use=Everything quite literally

Money=In the long run endless so not a factor.

Wrong again. Wow. Where are you getting your info from? All I can say is it's wrong.

Maximum pressure- Care to define this loose term you just threw in? Feel free to be more specific in term of PPP, MBT, etc in a SI engine.

Cmon, people have made legit attempts at helping you out but seems like you need to help yourself out for now. You need to be more realistic about your goals..

This is how I read this post:

I want to make the most power but not too much power
I want to use my car for everything and anything
I have no certain budget, but if I did it wouldn't matter


It should read:

I want to make upwards of 200whp, with room to grow
I'm uncertain of what I will do with it, but def not -rifting
I'd like to have a quality build, but need ot cut corners in order to stay under 5k


Otherwise, stick with my very simple and specific answer...41-43lbs

In my time around miatas, IIRC that is, I don't remember ever hearing of anyone talking about 30psi and so on. I do believe there was a guy on here though that had a built motor and a larger turbo boosting around 25psi.

Don't be so concerned about rudeness over here. Lots of these guys on here are REAL LIFE tough guys. They are fucking dead serious with you dude. ;)

Vash-

I give up, good luck.
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Umm peak pressure is what usually brakes a engine. So you're saying the power is what breaks a rod, piston, headgasket and not pressure. LOL:noob:

Your avatar is fucking hilarious. So is Vash's.

Also, just to get this in here: :drama:

tard, not the power, the attempt to make said power. 30 PSI through a T3:ne:30 PSI through 14B (one will undoubtedly explode btw)

you should be asking how much power your motor may handle (5 speeds don't break at 15 psi) not how much pressure

I ran 30psi from a T3/T4 with no issues! As mentioned above.. AMount of boost probably won't be your problem. Transmission will be.

LOL, you obviously don't know as much about engines as you think you do. How about MEP?

Thanks for input. Well rudeness to someone who can bring info and experience and without even understanding who they are talking too or the question being asked is not someone I wish to deal with in order to stay on this forum if that is what it comes too.

Wrong. You've been here like a week and you think you can tell us how to run our forum? Fuck off. If you want, you can eat a piece of humble pie and understand that everyone here isn't a total ass, but when you mouth off to senior members you can expect a serious bitchslapping. We all know a hell of a lot more than you do (you've proven that categorically in this thread). You have two options: Apologize and we can all nicely explain to you why you're wrong, or keep acting like a dick and we'll run you out of here faster than Hitler ran the Poles out.

Wrong. Power is the only comparison that matters, and I'll explain that after the next time you're wrong.

Totally wrong. Boost pressure is nothing more than a measurement of restriction in the intake manifold. What actually matters is pressure in the cylinders, which is directly related to torque.

Totally, utterly wrong. Motors are designed to take a certain compression pressure, which is directly related to torque. It really doesn't care what the pressure in the intake manifold is, which is all you measure. Boost is actually a pretty arbitrary, bullshit thing to measure or base power readings off of; this is demonstrated quite well by the fact that y8s makes 257whp from 9psi, but it takes most people 16-17psi to make the same power.

You need to stop insulting us. It's our forum and if you don't like it, you're welcome to get the hell off of it. If you're willing to learn, and respect the people here who know more than you do, you'll learn a hell of a lot from this forum. I know I did.

So you still say power and not pressure? If so don't waste my time.

after you have treated our lovely forum like a $0.05 whore with your post spamming?

Thanks Marc. Yeah I will try to find the limit of the 6-spd. We will findly know how strong they are. Then again i remember reading someone pushing 470 through theres. It was the e85 build. I think he was running 6-spd. So maybe the engine would go first.

WTF I posted 10 times in the BS section so that I can pm a couple members so that I could buy there products. I don't think they minded I posted in the bs forum.

Goddamn it, do I have to do everything around here... the answer is 28.64psi. At 28.65 EVERY B6 and BP will crack on the front side of cylinder #3 at 11:48a.m. while on your way to lunch. You will leave an 84ft oil slick, and drop 4 pieces of rod in the oncoming lane, in front of the red PT Cruiser doing 49mph in a 40 mph zone. DUH!!! :bang:

Seriously though, I dont think this is a very good question. Its like asking how old will I live to be. Some engines may handle more or less depending on many variables. No magic numbers Im affraid.

well one of the threads was mine and I do mind, so now I'm whoring your thread in retaliation

^ Payback is a bitch! :bowrofl:

Many folks have been hit with the ban hammer for the same deal. Its kinda frowned upon here. 5 more posts :jerkit: 6 more posts :jerkit: is kinda aggravating. At least post and share some actual thoughts you know.

On a side note this is a VERY popular thread at the moment. :giggle:

Vash-

So when have the failures occured then? I haven't been able to find any built bottom-end failures caused my too much boost.

Ohh aren't we mature. Have your balls dropped yet?

I know you are trying to make a point but those words and Miatas just don't go well together.

I understand it was frustrating but I could have either done that or started 10 useless posts about videos or jokes. Thought I would make it quick and painless.

LOL Whats u talking about i'm a tough guy.:magna::greddy:

I searched on m.net for "built motor boost" and came upon some threads. This one seems to have a similar question/debate.

MX-5 Miata Forum - How much power is this engine good for?

Vash-

Thanks haven't read that one. Cliff notes it said 22psi should be safe. Its for a 1.6l but should be similar enough.

If you read a book about it you'd realize that M3/min or CFM is the measure of power.
Boosht ish ther mershur of baaakkpprressuurre in ther innntaaakkke seeestum.

That ther's yer problem. Ya still don't fuukin' lissen.

GT2554 at 15psi < t3/t4 at 15psi (the CFM's are different and the HP's are different.)

CFM of air plus fuel equals HP. How many CFM can my engine handle equals how much HP can my engine handle. And PSI is almost completely irrelevant to that equation other than the fact that excess PSI makes heat and counters efficiency.

You want your engine to flow as many CFM as possible with as few (relatively) PSI as possible if you are looking for total highest peak HP possible.

The problem is you think everybody's a dick for not lying to you.

Person 1: "How high is the sky?"
Person 2: "Well, it starts there and keeps going up and up."
Person 1: "Yeah, but how high is it?"
Person 2: "What part?"
Person 1: "The sky! How fucking high is it?"
Person 2: "There is no one answer!"
Person 1: "You're a dick!"
Person 2: "I'm not screwing with you. There is no one right answer."
Person 1: "Fuck you! I'm leaving!"
Person 2: "Bye...(sighs)...Dumbass."

or you could have just done nothing and posted only when you thought you had something to add or a sensible question and become a respectable member of the forum.

think about it for a minute: if it's ok to post 10 worthless posts, then why have the limit in the first place?

did you consider trying to ask a moderator/admin for some help?

BTW - There's a guy on here from Greece running ~2.5 BAR of pressure.

Yes, he should send Savington a few PM's :giggle:

The reason I didn't wait is because I needed to make sure the item was still for sale or I was going to bid on item on ebay that was ending.

I didn't ask an admin because I honestly didn't think it would be that big of a deal since it was in the bs forum and no one would mind. Heck I thought some people would think it was funny. I also thought anything goes in there.

Waste your time. Lol. I can assure you the feeling is mutual.

Seriously, look back at your computer screen for just a second. Count how many people are telling you you're wrong. Also look at these people's post counts. Consider the fact that you could be wrong.

You seriously don't get it. Here's a realllllyyy simplified way of putting it

Fuel burned/unit time = HP Burning fuel is the goal. Period.

To burn fuel, you need oxygen. A turbocharger will increase the density of the air going into the engine. Denser air= more oxygen. However, the compressor of the turbo gets its' power from the turbine. The turbine places a restriction on the engine, causing back pressure. Small turbo's have smaller turbines that place a larger restriction on the engine. This causes a larger pressure (read, enthalpy) difference across the turbine, resulting in more shaft work to drive the compressor. So a turbo with a very restrictive turbine will spool fast, but won't make much power. Where as a turbo with a large turbine will spool slowly, but once spooled, will make more power.

It does when you're asking retarded questions that could be answered with a search.

Notice how I've registered over a year ago and have less posts than you? Lurk more you colossal ------.

100% serious, I'd be more than glad to sit down for like 15-20 minutes over AIM and explain how internal pressure work, and why motors fail under torque and not pressure. If he is willing to be open to ideas that aren't his (and aren't wrong), I'll gladly put the time in to help him understand the correct ideas.

My AIM is Savington, and I'm dead serious.

Finally someone undestands its about flow. But since every engine is different and I didn't want to get technical just a ROUGH estimate I said boost. Since the main thing that determines flow in a turbo motor is BOOST! But once again they didn't say that untill now. They have been saying power and transmission and search. Which I know doesn't have the answer i'm looking for.

Wow, how many ways do you have to explain it Sav? He's a thick one.

Boost:ne:flow
Boost:ne:flow
Boost:ne:flow
Boost:ne:flow
Boost:ne:flow
Boost:ne:flow
Boost:ne:flow
Boost:ne:flow

Have you read all my posts. I know its not boost but pressure. What does pressure equal. Torque. But did I ask about that. No I asked A ROUGH ESTIMATE ON THE BOOST PEOPLE RUN BEFORE THERE MOTORS BLOW UP!!!

I missed Sav's earlier post on torque. I never argued it wasn't torque.