adamlewis

What do you all think. The only thing there to help fuel delivery is a Walbro 255lph HP, and a Haltech E6K.

Do you all think its possible? ( nevermind all the "is it efficient" b.s. )

Dan H

The stock turbo already gets horribly inefficient at more than 12 psi or so I would say. At that point, its not making power, just more heat. Its overkill in my opinion.

adamlewis

Anyone else want to throw their hat into the ring?

adamlewis

Also, does anyone have a compressor map for the HT-18?

I know everyone says its so inefficient there and makes no more power, but Id like to know where their getting this data.

NZConvertible

It's not BS. No manufacturer in their right mind is going to use a turbo that is still efficient at that boost, because then it wouldn't be any good at the stock boost levels. Same with the IC. Because of bugetary constraints, factory IC's are nearly all smaller than ideal even at stock boost and power levels, let alone at that crazy boost level.

I'm sure it's been done before, but to make it last more than a week you're going to have to tune it to run bulk rich at full load to cool the air/fuel mix enough to stop detonation, which can cause all sorts of problems like oil being washed off chamber walls. It's unlikely the injectors are even big enough to provide that much fuel. In the mean time the turbo's bearings will be eating themselves because of the excessive shaft speed.

It's unlikely you'll even be getting that much more power at 19psi as you would at a more sensible boost level. Excessive heat and rich mixtures are the exact opposite of what you want to make good power.

I'm curious as to why you need that much boost. It sounds like you just want to be able to quote big numbers...

Josepi

I've started seeing duty cycles ~90% with just 11psi on the stock injectors using a LT8. Of course that's in high load scenarios.

adamlewis

I was just curious if you all think an engine would last at 19psi. Thats all.




And does anyone have a compressor map?

Fingers

Uhh if you have the right fuel to support it, and the turbo is efficient at 19 psi, i don't see why not.

adamlewis

Thats just the thing...all these people are saying its NOT efficient ( yet have no real data to back it up ), and saying that I dont have the fuel ( yet I obviously do... ).



Just thought it was a little bit funny.

rotary>piston

It's a known fact that the stock turbo is crappy at those boost levels. If you're so set in finding out, go ahead and do it. Any power increase you get from the extra boost will be far overruled by the incredible heat and resuting timing retard. It may also just detonate like crazy too.
It's your car, do as you like.

1FastT2

iTrader: (1)

I have seen the stock turbos presonally blow oil seals quite quickly above 14psi. There is no power to be had above 12-14psi anyways, its all downhill from there.

RylAssassin

Yeah but he says he wants proof.
Well what are the chances Mazda chose a "Super Turbo" that was engineered for up to 8 psi of boost but could go up to way past 12psi and still be efficiant. I mean its completly illogical. Why or how would they chose a turbo that could be efficiant past a psi then what the turbo was designed for?? Thats how i look at it and thats why if im going to have a goal of 20psi in mind im going to find a turbo made to handle or boost to those levels...

Dan H

What is real data to you? Are a few forum members stating facts and experiences not enough for you?

n4ji

iTrader: (1)

I think the only engine strong enough to handle 19psi is the 2JZ... That thing is a beast.

a7r

OT, but my 2000 Volvo V70 R AWD (wagon) was running a reliable 20 pounds of boost on the stock turbo and pump gas. There are 'tons' of other blocks that can handle that kind of boost (e.g. 4G63, RB26, LM9). Just Say No To Supra Whoring.

adamlewis

Thats the thing. There is noticeable power ( in my experience ), and no audible knock ( yes, I know not all knock is audible ).

How is it a known fact? How did you come upon this fact? Was it just another persons word?

adamlewis

No, because I dont know where theyre getting the data. I could pull some random tidbit out of my ***, but just because other members hear it and quote it as truth doesnt mean it is.

I want a compressor map. If these people are so sure that it becomes so horribly inefficient, they must have seen a compressor map.

Evil Aviator

Just make your own compressor map. All you need to do is plumb an air temperature sensor at the turbo inlet and outlet to get T1 and T2 (convert deg F to deg R), plumb an absolute pressure sensor at the turbo inlet and outlet to get P1 and P2, and attach an optical tachometer to the front of the turbo (most turbos have one blade painted for the optical tach to pick up). Then, simply run the car on a dyno and log the data. Once you do that, then you will be able to plot your own compressor map that you did all by yourself so you don't need to worry about any unreliable data.

BTW, your turbo is going to puke its seals long before it gets to 19psi boost unless your engine blows up first, so you may want to start at lower boost levels and work your way up so you at least have some data for the cost of sacrificing your engine.

Avatar

In an FC you will notice that the engine starts to lean out at 10 psi, a few people have managed to get upto 14 psi, however I have not heard of any that have lasted very long with out a front mount and better injectors.

If you look into how a turbo works, you'll find that it has an optimum boost level, going above OR below that point effectively heats the air.

Now if you take your car for a bit of a thrash and then take the temp of IC you'll see that it is already hot at standard boost.

I can not provide you with any compression maps, but if you take your car to a dyno and increase the boost in increments you'll soon learn what these guy's have been saying is correct, so you can either learn from the experience of others or go ahead and prove us wrong.

adamlewis

I appreciate your information. I was ignorant about the whole process of mapping a compressor. Its a neat little tidbit to know.

That said, it still doesnt answer my questin as to where you all got the original data.

My turbo didnt puke its seals last night. Maybe I got lucky. Who knows.
I do know that my car sees anywhere from 13-15psi on a daily basis though.

adamlewis

I know how the turbo works...I know how crappy the IC is...and I know how small stock injectors are. This is all I can seem to get from this forum anymore. All I had was one simple question about how you all got your data, and nobody has really given me a straight up answer.

While I havent been to the dyno, I have referenced my car on a certain stretch of straight road and against a friends car while Ive been turning up the boost. I will tell you that 15psi is a noticable difference from 11psi, and 19 is also very noticeable from 15.

At 11psi, the car just feels quick. At 15psi, the front end starts to float some, and my seat belts will lock from a roll in 3rd gear. I knew my car felt faster last night in 4th gear, but I didnt even know how much boost I was running. I had tightened my MBC earlier that day and obviously tightened it too much. All I know is it honestly FELT faster. It was a big enough difference to make me turn on the dome lights and check my boost gauge ( gauge light burned out ) and see the needle at 19.

Im not saying that the engine would last at 19psi. Im not saying the turbo will last...Im not saying the injectors arent being overworked.
All Im trying to say is that the gospel that Ive heard of for so long doesnt seem to be right anymore now that Ive actually experienced it first hand.

Avatar

What exactly is your "Jspec" engine.... did you buy the entire car as an import or did you buy and FD engine with turbo?

HAILERS

Well, I've done part of what EVILROTOR mentioned above. I have a Fluke52II which is a digital thermometer. It's a dual thermometer.

At a steady seventy mph I see approx 120 degree input to the intercooler and approx 83 degree air on the output side of the intercooler (That's one good intercooler!). That is on a 75 outside air temp day in Texas (cold on Sep 1st).

Under WOT full boost, uphill, I captured 238 degrees inlet temps on the intercooler. That's with a virtual stock turboii engine. Somewhere b/t 6 and seven psi. Series four. At that time I did not have the second temperature lead in the outlet of the intercooler, but I bet it was waaaaaay above 85 degrees.

I blew the intercooler inlet duct off under full boost (forgot to tighten the hose clamp after installing the probe) which caused the engine to die and resulted in major trauma to my mental state (oh gosh, I blew the engine!) and quit experimenting around for the rest of the day.

Just my way of saying the inlet temps go to the extreme even on a stock turbo setup.

But the stock intercooler impresses me, what with a temp drop from 120 down to 83 across the core at a steady 70mph.

NZConvertible

You seem extremely unwilling to accept the knowledge and experience of others.

The chances of finding a compressor map for an 18yo OEM turbo are virtually nil (OEM turbos are not off the shelf), so you might as well give up on that.

As mentioned twice above, Mazda would no sooner have used a turbo as efficient at 19psi as it is at 6psi than they would've made an FC that can fly to the moon. It makes absolutely no sense.

Anyone who's measured the intake air temps that result from pushing stock turbos to very high boost levels will tell you the same thing. They get crazy high. All turbos do that once they're past their efficiency peak.

Same with over-speeding the shafts. Higher boost comes from higher shaft speeds, and stock bearings are only designed to cope with stock boost levels. Many, many people have blown turbos not long after cranking the boost way up.

Fingers

If mazda was anything like mitsubishi when they slapped a big 16G on the Galant VR4 engine, with 510cc injectors to back it up, i'm sure you'd be singing a different tune I love my DSMs