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Discussion Starter #1
Just curious - It seems a majority of people that post their dyno numbers after their 1st or 2nd tune at SRT and/or PFS max out at 17 psi. A good number of those people have gte internals/gte block, large injectors, and even tranny upgrades. What's the reason for stopping at 17 psi? Is it for reliability?

I feel like now that I've spent all these thousands of dollars (built block, stand-alone, larger injectors), I want to make the most out of it. On Audi, VW, RSX, Mazdaspeed forums etc., most of the boosted guys are tuning around 20~22 psi on their GT28R, GT35R, 60-1, 50 trim etc. If we have the upgrades to support more boost, why don't Mo and Ray typically tune beyond the norm? Or, do I have a misperception?

Thanks all! :)
 

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one reason is majority of the cars are autos...17 pi will put you around 420-430, of course a built/tt block can take more, but you'd probably be pushing it on the trans even with sprag and vb if you try to crack 500+, why risk it. rather put out a reliable, daily drivable car thats fast, than worry about being on the borderline of disaster. plus there are so many other factors such ems limitations, etc...way too many factors to generalize and say 17 seems to be the limit.


Just curious - It seems a majority of people that post their dyno numbers after their 1st or 2nd tune at SRT and/or PFS max out at 17 psi. A good number of those people have gte internals/gte block, large injectors, and even tranny upgrades. What's the reason for stopping at 17 psi? Is it for reliability?

I feel like now that I've spent all these thousands of dollars (built block, stand-alone, larger injectors), I want to make the most out of it. On Audi, VW, RSX, Mazdaspeed forums etc., most of the boosted guys are tuning around 20~22 psi on their GT28R, GT35R, 60-1, 50 trim etc. If we have the upgrades to support more boost, why don't Mo and Ray typically tune beyond the norm? Or, do I have a misperception?

Thanks all! :)
 

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one reason is majority of the cars are autos...17 pi will put you around 420-430, of course a built/tt block can take more, but you'd probably be pushing it on the trans even with sprag and vb if you try to crack 500+, why risk it. rather put out a reliable, daily drivable car thats fast, than worry about being on the borderline of disaster. plus there are so many other factors such ems limitations, etc...way too many factors to generalize and say 17 seems to be the limit.
The auto tranny with vb mods and sprag is only good to 420-430rwhp?
If that is true then I'll stop the mods with meth injection and scrap plans
for TT internals. Is this the concensus on the auto tranny?
Wayne
 

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I will venture to say that another limitation of MOST not all of our cars is the GSS342.... A great pump but 500ish is def getting close to it's limits . Just a thought.
 
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Most people dont run more than 17-18psi w/o meth/water injection b/c at that pressure your risking detonation. The stock GE intake design also limits the available volume that the manifold has available for combustion making your turbo work fairly hard and elevating the temperature. The GTE internals are also at the upper limits of their tolerances, in order to make more power you optimize the intake path in the case of a converted GE, not just turning up the boost. You can also never be certain of the quality of your gas, unless you use 1 station everytime.


Also, every engine design is different, you cant really compare a VW 4 banger to a GTE, they are 2 totally different machines.

EDIT:

WTF do transmissions have to do with engine operating pressures? Jesus.:rolleyes:
 
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I didn't say that was the limit, but those numbers seem to be the norm of safe range for a reliable daily driver when there are known limits. of course they could hold more but you set each car to have a reliable safe limit. Alot of times people don't understand things from a tuners perspective, having a good safety window and putting out a reliable car is much more important and I can say thats probably why we have had no serious mishaps with any of our customers vehicles.


The auto tranny with vb mods and sprag is only good to 420-430rwhp?
If that is true then I'll stop the mods with meth injection and scrap plans
for TT internals. Is this the concensus on the auto tranny?
Wayne
 

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Most tuners don't tune the cars above 17/18 psi because they tune the cars to be driven on pump gas. and thats pretty much the highest boost level to run safely on pump gas. i wouldn't do more then 19psi on pump.

A lot of is300's/supras run a little more boost then that..maybe 23/24psi..and this is because they have Alcohol/methanol injection to aid the engine.
 
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Discussion Starter #8
Thank you for clarifying. Reppage 4 u all!
 

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Most people dont run more than 17-18psi w/o meth/water injection b/c at that pressure your risking detonation. The stock GE intake design also limits the available volume that the manifold has available for combustion making your turbo work fairly hard and elevating the temperature. The GTE internals are also at the upper limits of their tolerances, in order to make more power you optimize the intake path in the case of a converted GE, not just turning up the boost. You can also never be certain of the quality of your gas, unless you use 1 station everytime.


Also, every engine design is different, you cant really compare a VW 4 banger to a GTE, they are 2 totally different machines.

EDIT:

WTF do transmissions have to do with engine operating pressures? Jesus.:rolleyes:
This is the only reply that matters to the first post, the ones above and below having no "on-topic" info what-so-ever. A saying comes to mind... something about removing all doubt... heh.

The physics of compressing air at about 17-19psi going into a 8-9:1 cylinder you are creating so much "intake air temperature" and/or the components in the cylinder are so hot that the heat alone is causing the fuel to ignite before it is supposed to via the spark plug. This is called "Pre-Ignition." This is the reason you must "cool down" the fuel/air, via some sort of injection system, or increase your octane, or both. Pre-Ignition will kill an engine QUICK... you should read some of the threads linked in this thread. Also read the Detonation FAQ and Pre-Ignition FAQ's for further explanation and understanding.
Please people double check the question being asked before posting. Don't just go repeating something you "heard" or that "so-n-so" posted on the hoppedupriceboosters.cum/forums either, by doing this you are doing a disservice to yourself and the entire community. There's enough misinformation out there already, let's try not to add to it here, thanks!
 

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I difine detonation as the fuel/air ignites via the spark plug, but rather than a slow controlled burn, its an explossion (becuase of either lean conditions, or heat or a combo of those conditions) thus bad. Would timing thats too aggressive fall into this catigory also? Does that make the piston rings make the same sound as with detonation?

Igniting before the spark event bacuase of way way too much heat being present is pre-ignition IMO.

Just want to make sure I've got it right.

More on topic if you want to make more power than 17psi I think the tuners usually make the setup more effecient so that even at 14psi, it makes more than what it used to at 17psi. Like the others stated, more psi doesn't make a linear line of power increase, it gets to the point its like a dog chasing its tail, the gain in power is negated by effeciency losses.

SRT has made some really strong numbers with their custom setups with "low psi". Its more important to flow the air, than build up pressure. High pressure indicates there is a bottleneck somewhere, so when peeps go the distance of custom intake manifolds, port and polishing, cleaned up turbo manifolds, exhaust, well researched turbo housings etc etc, the flow resistance is decreased, more air actually moves, even with lower psi readings, more power is being made as the "air pump" the engine is has become much more efficient. This is teh goal for tuners with a good budget IMO.

Thats why I got a laugh in the old LMS days when some of the kit owners didn't want to get exhaust and what not because there was a psi drop from those mods. It was a good thing, not a bad thing.
 

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I define detonation as the fuel/air ignites via the spark plug, but rather than a slow controlled burn, its an explosion (because of either lean conditions, or heat or a combo of those conditions) thus bad. Would timing thats too aggressive fall into this category also? Does that make the piston rings make the same sound as with detonation?

Igniting before the spark event because of way way too much heat being present is pre-ignition IMO.

Just want to make sure I've got it right.
You are correct sir, I mixed the terms up...

here is the Detonation FAQ and Pre-Ignition FAQ for your reading pleasure! I will change my previous post to reflect proper terms so there is hopefully no more confusion as there has already been way to much of in this thread.
 

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I'd plus rep you, but I have to spread the love elsewhere yada yada.

Sir? No, I work for a living, and I know who my father is. Thanks though haha.
 

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Discussion Starter #13
Fantastic info! I'm sure there are a WHOLE LOT of guys like me that attribute the most of our power gains to increased boost. Boy, was I way off. But now it all makes sense. Especially after seeing a custom Altima coupe at the motor trend auto show today that made 457 whp at just 13 psi.

Now I'm chuckling at the local ricers with the homemade turbo kits that say all they have to do is "crank up the boost" in order to smoke whoever. I used to think that my w58 tranny (cryo treated) was what would limit SRT from producing more power, but it's actually much more complicated than that. I'm at a new level now - SWEET! :cool:
 
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Sir? No, I work for a living, and I know who my father is. Thanks though haha.
Sorry 'bout that... old habits die hard I guess... was brought up to address my elder's as Sir or Ma'am... it wasn't out of disrespect, just know that!
 

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Sorry 'bout that... old habits die hard I guess... was brought up to address my elder's as Sir or Ma'am... it wasn't out of disrespect, just know that!
His statement about 'working for a living' is a reference to being in the military and being enlisted as apposed to an officer in which case, he would be refered to as 'Sir'. Now the father part I'm in the dark on :confused:
 

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17 psi gets old fast in my opinion. i was driving at 22.5 daily and was loving it.
 

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Now the father part I'm in the dark on
Hollywood has killed the "I work for a living line", but a not so publicized line we use also is "no, not sir, I know who my father is" because someone who doesn't know who their father is, is a bastard, and officers are, well, you know.

i was driving at 22.5 daily and was loving it.
Your a G. I'm becoming a huge fan of water/meth injection, it really helps to raise the limit. Its a fabbing piece of art to intercool the TRD blower on the Tacoma (ie: I'm not even going to f'ing try), I'm leaning more and more towards getting the URD pulley and a water/meth kit. At the very least it'll clean out all that darn carbon from 147,000 miles lol (which in itself could reduce the ping lol).
 

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Hollywood has killed the "I work for a living line", but a not so publicized line we use also is "no, not sir, I know who my father is" because someone who doesn't know who their father is, is a bastard, and officers are, well, you know.
Now, that I have heard before... not sure why I didn't catch it the first time around... I wasn't ever a milbrat or in the mil, but I married a milbrat and have since picked up on a bit of the lingo... but then again her father was a captain so he was the one being called "Sir" heh... roflcopter!
 

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17 psi gets old fast in my opinion. i was driving at 22.5 daily and was loving it.
yeah...


at 22psi I would have atomized the w58's I was running, at 18psi I broke one in first gear.

Im actually kind of pissed that I never did it once or twice just to feel how it pulled. I know myself too well though, once I ran it I would have a hard time turning it back down. But hell, there's nothing around me that could even run with my car at 18psi, besides a GSX-R 600, which I still beat. The bike was the best competition I ever had, besides a LS3 vette. People would hear the twin SSQV's dump and start looking around for a car that might be turbo'd, look at me, and then keep looking. Lol, its not everyday, or at least it didnt use to be, that you would see a near 500rwhp DD cruising around with an "L" badge on it.
 
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