PSI vs HP: Which actually kills?
#1
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I know alot of misinformation goes around on different forums and that this forum is not necessarily immune to that. I was always taught that it is horsepower that kills an engine not PSI as everyone so freely spouts. Different turbos will flow different amounts of air at different PSI ranges. Therefore turbo A might make X hp at a certain PSI and turbo B will make Y hp at that same PSI. My interest comes from the fact that I am using a GT2554R in my initial turbo build and I want to know if I turn up to boost on it to say 18PSI on a mbc will my engine fail in any short order. The only thing that I would even think that might would be the headgasket. I have read posts on this forum and miata dot net about people running upwards of 300hp on a properly tuned stock engine but they generally run a little bit larger turbos at around maybe 12PSI.
I have built high compression NA engines before and from my experience they have internal cylinder compressions that are much higher than a turbo car and I have successfully used stock headgaskets and parts without failure.
I'm not looking for comments on "You should get a bigger turbo", etc... I just want real world advice from a member with experience of running high PSI to the limits of a smaller turbos efficiency range. I don't track my car yet and wouldn't be able to afford the proper suspension components for years to come, so a small turbo is perfect for me as a daily driven car. If I can get the most out of my gt25r to increase my powerband in the higher rpm range I would prefer that option.
To reiterate, my current understanding is that with a proper tune and cooling, HP kills engines before high PSI.
Brian
I have built high compression NA engines before and from my experience they have internal cylinder compressions that are much higher than a turbo car and I have successfully used stock headgaskets and parts without failure.
I'm not looking for comments on "You should get a bigger turbo", etc... I just want real world advice from a member with experience of running high PSI to the limits of a smaller turbos efficiency range. I don't track my car yet and wouldn't be able to afford the proper suspension components for years to come, so a small turbo is perfect for me as a daily driven car. If I can get the most out of my gt25r to increase my powerband in the higher rpm range I would prefer that option.
To reiterate, my current understanding is that with a proper tune and cooling, HP kills engines before high PSI.
Brian
#3
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mutiple things can cause engine failure, engine temps , boost spikes,oil line failure, ingnition failure, bad timing, various and numerous causes are key to engine death, indeed high pressures due to boost levels being set at levels beyond what it can handle can cause severe if not total destruction on the engine its self, resulting in more expense!
#6
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
mutiple things can cause engine failure, engine temps , boost spikes,oil line failure, ingnition failure, bad timing, various and numerous causes are key to engine death, indeed high pressures due to boost levels being set at levels beyond what it can handle can cause severe if not total destruction on the engine its self, resulting in more expense!
Assume that I have a perfect tune and that there are not any misc leaks or overlooked lines. Can the stock engine handle that. If there are "many factors" this is the place to discuss them then.
#7
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As far as i have seen the motors are very stout i have haerd ring waer and everything else is accelerated at 15+ psi from fm but other than that they seem to be very stout. So long as you have the fuel and cooling to handle the flow of the turbo there is no reason a high psi setup cant last awhile on the stokc motor but as i said before the normal wear life of the engine seems to accelerate at this level of boost, pherhaps it is all a function of the heat in the system and some silent knock but i see no reason you couldnt run that much boost but the 2554 at its best only produces about 27 lbmin of air flow and it does this at 14.7 psi roughly so over boosting would mean less flow. you would be lucky to go past 250 chp with that turbo.
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