So ill be getting my setup tuned in a few weeks hopefully and Im debating how far to go in terms of psi and power.

I want to break the 280whp mark but Im concerned past the 15psi range. I know 280whp will be held fine, so does it make sense to go to whatever psi it takes to make my power goal rather than setting a psi limit of say 15?

 

And what engine are you running again?

 

I think both goals need to be kept in mind when building an engine.

To say you want 280 horsepower is a goal to keep in mind, but also keep a PSI goal in mind too.

Say a in terms of a T3 or a B18 will net you 280WHP at 18 PSI... well thats not practical unless you are a good tuner/sleeved/whatever.

Though 280WHP on the same B18 with a T3/T04 will net you 280 at 12PSI is much more practical for your stock sleeves/turbo effiency/etc.

So in essence yes you are right, but keep a goal/limit in works with each other and it should work out fine.

 

Yes sorry, I didnt give much in the way of detail since Im not really asking IS IT SAFE, more, is my logic correct.

For those who want to know, it is a stock sleeved d16z6 w/ eagle rods and arias 9:1 .020 over pistons. Mild headwork, log manifold, open dump tial 38mm, turbonetics 50 trim t3/t4 with .48ar exhaust.

I KNOW the block can handle 280whp. But say for some reason it took 18psi to get it as oppose to 15psi on a 57trim. I am no worse off correct since the turbo is still well within its efficiency range.

Z6 sleeves have been proven will past the 300whp mark, so does it seem ok then that I simply run whatever psi it takes to hit 280-290whp? Or am I missing something in terms of psi vs. cylinder pressure etc etc?

 

To add to my last post, tuners are always saying I dont like tuning stock sleeves past XXpsi. Why would they say that rather than I dont like tuning them past XXXwhp?

 

tune for the hp. not the boost.

 

Did anyone ever think that a average stock gsr cranking comprsssion is around 180 psi. Kinda makes you wonder whats the difference between 15 psi and 20 psi?There are many variables, afr, total timming ,inlet air temp, water temp egt's, combustion chamber effciency,fuel, spark plug heat range, crank case pressure. Lots to think about...

 

Sure but thats not really the question here.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by OrangeBoost &raquo;</TD></TR><TR><TD CLASS="quote">Sure but thats not really the question here.</TD></TR></TABLE>
I think it is if you read ....

 

I asked the question. I know what Im asking. I realise that all the little variables will change slightly, but that is a given.

 

what is the big deal about boost pressure? it is cylinder pressure that breaks things....

 

It's a great question that isn't answered simply. If you have a t25 turbo on say a 1.8L engine pushing 16PSI is kinda hard to do since the heat generated by using such a small turbo for that PSI can be dangerous for an engine. PSI doesn't break anything in terms of sleeves or valves or anything of that sort, it simply isn't enough pressure to break things by itself.

With that being said, I whould like to point out that you can't just run whatever PSI either. With higher boost pressure comes higher density charge meaning faster burn rate meaning less timing will be needed for correct burn. With higher PSI always comes more heat to the intake charge as well which again speeds up the burn rate, so be mindful of that too. A lot of knowledgeable people can go on and on about the little things you need to watch out for, but that is the tuning process.

To answer your question, NO PSI is completely irrelavent to breaking parts (under say 50PSI), BUT a lot of people think otherwise and have the <U>RIGHT</U> to because in pushing higher PSI not only do you gain significant horsepower, but also have to deal with many things some of which I mentioned here.

So yes you can run XX PSI as long as your setup can take it (HP wise) and your system is well tuned....minor slip ups at high boost is more likely to break things then lower boost levels hence why people get scared

Hope I helped

 

i would say shooting for a set power goal is good, we all have to have goals or this is pointless.

but you have to have a happy medium in your tune. surei would say i wanna make 475, pull a bunch of timing and crank the boost up to 25psi, yeah i will make the power, but how well will the car run? probably crappy, and will spool slow, and just not be what you wanted.

have a power goal in mind, and a limit of how far you wanna go. but dont do whatever it takes just to make the goal.

if you dont hit your mark, do some more research and find out why, and overcome the indifference

 

Good replies. Yes I realise heat will become a factor but I really dont think a 50 trim is too small for 280-300.

I know these power levels are extremely acheivable. Im just not sure what boost it will take since Im lacking a couple things like zex cam and EL manifold that others Im comparing to are running. Im hoping I can safely offset the difference by an extra psi or two.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrbsponge &raquo;</TD></TR><TR><TD CLASS="quote">
have a power goal in mind, and a limit of how far you wanna go. but dont do whatever it takes just to make the goal.

if you dont hit your mark, do some more research and find out why, and overcome the indifference</TD></TR></TABLE>

Very good

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by littlebluecrx &raquo;</TD></TR><TR><TD CLASS="quote">what is the big deal about boost pressure? it is cylinder pressure that breaks things.... </TD></TR></TABLE>

exactly.. you're placing less stress running 15psi on smaller turbo and making 280whp vs 320whp at 7psi using big *** turbo

another thing to consider is.. if whatever turbo yo'ure using is still in efficiency range at that hp level.. and you're likely to have a better powerband with smaller turbo if its running right in efficiency range @280whp vs large turbo at few psi and late spool time.

 

The situation I am looking at is more along the lines of 15psi 300whp on a bigger turbo vs. 19psi 300whp on a smaller turbo.

Or even keep the turbo the same 300whp @ 15psi w/ cam and and EL vs 300whp@ 18psi w/out cam and w/ log manifold.

 

I am curious about this whole idea of tuning to achieve a certain hp level vs tuning for a given boost too..I guess if you know what your block can take and as long as you're under that without encountering knock at whatever boost/octane you're at, you're all good..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by OrangeBoost &raquo;</TD></TR><TR><TD CLASS="quote">The situation I am looking at is more along the lines of 15psi 300whp on a bigger turbo vs. 19psi 300whp on a smaller turbo.

Or even keep the turbo the same 300whp @ 15psi w/ cam and and EL vs 300whp@ 18psi w/out cam and w/ log manifold.</TD></TR></TABLE>

i guess choose whichver can give more desirable powerband. don't base it solely on psi.. if smaller turbo going to be choking at 19psi to make 300whp and you have the use for top end then you should go with larger trim.. easier said than done..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by OrangeBoost &raquo;</TD></TR><TR><TD CLASS="quote">So ill be getting my setup tuned in a few weeks hopefully and Im debating how far to go in terms of psi and power.

I want to break the 280whp mark but Im concerned past the 15psi range. I know 280whp will be held fine, so does it make sense to go to whatever psi it takes to make my power goal rather than setting a psi limit of say 15?</TD></TR></TABLE>

Here is the deal. Peak power doesn't mean ****. You have a D series... which means LAG. If you want to make say 30more whp at a lower psi you will sacrifice your midrange power a bit. How much exactly? Well that depends on your turbo selection.

As jason said earlier, there is a lot more that comes into play to answer your question. But if you want a joe schmoe easy answer that's not too in depth, then run more boost but take out more ignition timing using a smaller trim sized turbo. Reducing your ignition timing will greatly lower your peak cylinder pressures. Lower cylinder pressures means less chance of cracking a sleeve. Boost pressure is not exactly a direct indication of your peak cylinder pressure... but we won't get into that since you want an easy answer.

I did a D series tune last year and here were the results and specs:

http://www.av-engineered.com/c...t.htm

This engine had a shitload of problems though... it definetely should have put out a bit more power. For some reason the dyno chart is not on there... but if I remember I believe he started making power around 5200rpms. It was pretty laggy in my opinion.

 

your powergoal is achievable, we just did a very simple setup that did right at 180@ 8psi from a smaller turbo

i learned after about 20 different turbos and combinations and manifolds and such. find your all around goal and build it

dont throw parts at the car and expect power cause you will always be disappointed; i always was.

 

as far as the tuning aspect, off the topic off turbo selection, don't you just keep advancing boost with the timing at whatever makes the most power (mbt) until you reach the knock threshold with whatever octane you're using? Then if you still want more power, venture into the land of diminishing returns and say f mbt, taking out slightly more timing than whatever is necessary to avoid knock and turning up the boost until you get scared, or it just stops creating a worthwhile increase?

 

There are lots of variables, but most tuners would tell they would rather run less PSI and make more power.

Larger turbos can push a lot more power at a lower PSI, but would also mean they make less torque. Ever notice how smaller turbos would achieve peak torque a lot earlier in the powerband which would also mean more torque for the same given WHP. Torque is the actual amount of stress level inside the engine, HP is the output of torque at a given time (vs RPM). If an engine can make more power at higher RPM's and less torque, it is most likely going through less stress.

So yes, you can make safer power with a larger turbo at lesser PSI, but the higher HP numbers won't necessarily mean you would be faster. I'd rather make a bit lesser power with a smaller turbo, but with much better spool and linear powerband. If you want both smaller turbo and big power numbers, you are pretty much forced to increase boost to higher PSI numbers and be closer to the limits.

 

I chose my turbo due to the fact that I still wanted good peak numbers but didnt want insane lag since its a street toy and auto-x car as well. I do everything with it.

I figure the .48a/r housing will sacrifice my top end a little bit but I will gain a quicker spool so it will still be fun all around.