Turbos and Low Compression Pistons.
Discussion
Just trying to improve my knowledge here. I have a 3.2 Boxster that has had a turbo conversion, which was done by the previous owner. The engine internals are unchanged and the turbo only runs at 4psi. For what reason/further mods would you need to change to lower compression pistons?
The reason I ask is that I dropped an email to Hartech to find out how much their 3.2 to 3.7 conversion would cost, but they said it wouldn't work for me as they don't do low compression pistons for that mod. As the current engine doesn't have low compression pistons, why would the 3.7 upgrade need them?
The reason I ask is that I dropped an email to Hartech to find out how much their 3.2 to 3.7 conversion would cost, but they said it wouldn't work for me as they don't do low compression pistons for that mod. As the current engine doesn't have low compression pistons, why would the 3.7 upgrade need them?
I don't know about the Porsche engines. But you have a static CR (compression ratio) on an engine. Under boost a turbo will increase this compression ratio. The more boost, the more the CR will increase.
However too much compression and you'll run the risk of wrecking the engine and pre-det. So most turbo engines run a lower CR to allow more boost.
Years back this might have been as low as 7:1 but with modern fuelling and electronics you can get much higher CRs with boosted vehicles these days. Especially supercharged.
4psi does seem quite low. But as I said I know nothing about the Porsche engine or its static CR. However many other petrol engines that are n/a with aftermarket turbo kits, will often allow 6-8psi of boost. But sizing of the turbo will impact this too.
What sort of fuel are you running on? 95 or 99 RON?
However too much compression and you'll run the risk of wrecking the engine and pre-det. So most turbo engines run a lower CR to allow more boost.
Years back this might have been as low as 7:1 but with modern fuelling and electronics you can get much higher CRs with boosted vehicles these days. Especially supercharged.
4psi does seem quite low. But as I said I know nothing about the Porsche engine or its static CR. However many other petrol engines that are n/a with aftermarket turbo kits, will often allow 6-8psi of boost. But sizing of the turbo will impact this too.
What sort of fuel are you running on? 95 or 99 RON?
300bhp/ton said:
I don't know about the Porsche engines. But you have a static CR (compression ratio) on an engine. Under boost a turbo will increase this compression ratio. The more boost, the more the CR will increase.
However too much compression and you'll run the risk of wrecking the engine and pre-det. So most turbo engines run a lower CR to allow more boost.
Years back this might have been as low as 7:1 but with modern fuelling and electronics you can get much higher CRs with boosted vehicles these days. Especially supercharged.
4psi does seem quite low. But as I said I know nothing about the Porsche engine or its static CR. However many other petrol engines that are n/a with aftermarket turbo kits, will often allow 6-8psi of boost. But sizing of the turbo will impact this too.
What sort of fuel are you running on? 95 or 99 RON?
I run it on Tesco 99 most of the time. Never go below 97 though.However too much compression and you'll run the risk of wrecking the engine and pre-det. So most turbo engines run a lower CR to allow more boost.
Years back this might have been as low as 7:1 but with modern fuelling and electronics you can get much higher CRs with boosted vehicles these days. Especially supercharged.
4psi does seem quite low. But as I said I know nothing about the Porsche engine or its static CR. However many other petrol engines that are n/a with aftermarket turbo kits, will often allow 6-8psi of boost. But sizing of the turbo will impact this too.
What sort of fuel are you running on? 95 or 99 RON?
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