kvansic162 Posted June 2, 2008 Share Posted June 2, 2008 I plan on putting a turbo on my 280zx. I have nissan flat top comp. pistons in the block. If I switch from a N47 head to a P90, is a .796 drop in compression ratio worth the swap. Also cam I use the cam from the N47 on the P90 head? Quote Link to comment Share on other sites More sharing options...
z-ya Posted June 2, 2008 Share Posted June 2, 2008 If you are going for force induction, definitely swap the P90 on there. Flat tops with an N47 i too high a CR (10:1) for a turbo. The P90 will get you in the 8.5:1 range. You can use the N7 cam. Swap everything though (cam, rockers, lash pads). Keep them organized so they go back on the same cam lobe they were broken in on. Pete Quote Link to comment Share on other sites More sharing options...
kvansic162 Posted June 2, 2008 Author Share Posted June 2, 2008 That sounds like a good plan . I also have snowperformance water/meth injection kit on the car. Every little bit will help. Thanks Quote Link to comment Share on other sites More sharing options...
kvansic162 Posted June 2, 2008 Author Share Posted June 2, 2008 I forgot to ask if the stainless valves in my N47 head will work in the P90 head? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 2, 2008 Share Posted June 2, 2008 I forgot to ask if the stainless valves in my N47 head will work in the P90 head? No. Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted June 2, 2008 Share Posted June 2, 2008 This is from an artical I found. Engine Compression There are a couple of areas in which optimizing an engine for naturally aspirated power and forced induction power are at complete odds with one another. Static (engine) compression ratio is one of those. Most musclecar enthusiasts are readily aware of the fact that increasing the compression ratio of a naturally aspirated engine results in more power per unit of fuel combusted. The amount of engine compression that can be run is limited by the fuel octane that will be used. Forced induction engines are fundamentally different in that two sources of compression are available: the compressor and the engine. Effective compression is the term often used to describe the impact of the external compressor on the combustion efficiency. So how does a lower static compression benefit a forced induction engine? Let's look at an example. Compare these two situations: 1) On a stock 5.0 with ~9:1 static compression it is found that a non intercooled supercharger can run a maximum of 9psi of boost without detonation. The effective compression is ~14.5:1 and 320 peak rwhp is produced. 2) Same engine/supercharger combination but with low compression 8:1 pistons installed. It is found that a maximum of 13 psi can be run without detonation. Effective compression is again ~14.5:1 but significantly more air is allowed to enter the combustion chamber. Peak rwhp is now 380. In both cases the same octane fuel is used. Quote Link to comment Share on other sites More sharing options...
TimZ Posted June 2, 2008 Share Posted June 2, 2008 This is from an artical I found. Engine Compression There are a couple of areas in which optimizing an engine for naturally aspirated power and forced induction power are at complete odds with one another. Static (engine) compression ratio is one of those. Most musclecar enthusiasts are readily aware of the fact that increasing the compression ratio of a naturally aspirated engine results in more power per unit of fuel combusted. The amount of engine compression that can be run is limited by the fuel octane that will be used. Forced induction engines are fundamentally different in that two sources of compression are available: the compressor and the engine. Effective compression is the term often used to describe the impact of the external compressor on the combustion efficiency. So how does a lower static compression benefit a forced induction engine? Let's look at an example. Compare these two situations: 1) On a stock 5.0 with ~9:1 static compression it is found that a non intercooled supercharger can run a maximum of 9psi of boost without detonation. The effective compression is ~14.5:1 and 320 peak rwhp is produced. 2) Same engine/supercharger combination but with low compression 8:1 pistons installed. It is found that a maximum of 13 psi can be run without detonation. Effective compression is again ~14.5:1 but significantly more air is allowed to enter the combustion chamber. Peak rwhp is now 380. In both cases the same octane fuel is used. Ahhhh... "Boost Compression" - the internet legend that refuses to die. There is a good discussion on this subject here: http://forums.hybridz.org/showthread.php?t=114598 Quote Link to comment Share on other sites More sharing options...
kvansic162 Posted June 3, 2008 Author Share Posted June 3, 2008 Well that is good info. I hope to find a P90 head and go with it. I would be very happy with 300 rwhp. Thanks Quote Link to comment Share on other sites More sharing options...
roger280zx Posted June 3, 2008 Share Posted June 3, 2008 380 rwhp sounds like a slug of a blown 5 liter... maybe its just me. Quote Link to comment Share on other sites More sharing options...
Silent Posted June 3, 2008 Share Posted June 3, 2008 380 rwhp sounds like a slug of a blown 5 liter... maybe its just me. sounds like a mid 11 second car to me Quote Link to comment Share on other sites More sharing options...
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