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Discussion Starter #1
Ok here's my question,
I have a 93.5 P10 rated as 140hp
I read on a SPORTS COMPACT CAR article that the 91-93 or 94 SR20DE has a better intake cam that produces about 4-6 more HP, hence the fact that people look to buy 91 intake cams. If my engine already has this perticular cam, does that mean I have 145 HP? If so, why doesn't the factory specs say so?
 

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The low port 93.5 and newer engines have a smaller lobe intake cam and Nissan was able to regain the lost HP by retuning the ECU to offset the loss.

Wether you have a low port or high port engine, both are spec'd correctly at 140 HP. Your car actually is spec'd correctly at 140. That is not actually the horse power at the wheels, but what is spec'd by Nissan.

By replacing the 93.5 and newer cam with the more aggressive 91-93 cam, you've essentially gained approx. 6-8 HP.

Depending on your actual manufacturer date, you could benefit from replacing your intake cam.

Do you have a high port or low port engine?
 

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Factory specs assume HP at the flywheel. When you see HP chart plots (dyno plots) in magazines, they are referring to HP at the wheels.


You car is put on a machine and when you accelerate you spin a large drum. This measures actual "real" HP at the wheels after all the power loss through the drivetrain.


For example, a 99 G20 is rated at 140HP, on a dyno it produces 124WHP (wheel horse power)


A '91 intake cam may provide more power to the wheels. The factory still says the engine is "140HP" at the engine, however on a dyno you may see 128WHP.

=)


The wheel horsepower is calculated by how fast you can accelerate the drum. This is called an inertial dyno because it is measuring the inertia (power needed to put something into motion) this is said to be very accurate reading of real power


The most accurate reading (less commonly found) is a brake dyno. This works backwards of the inertial dyno. HP is measured by how much braking force is needed to stop the rolling drum. This is known as "BHP" (brake horsepower)


So stay alert to "HP" "WHP" and "BHP" they make a big difference!
 

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b-b00gie said:
So stay alert to "HP" "WHP" and "BHP" they make a big difference!
Thanks fo the technical side of it. Mine was kinda 'In a Nutshell' explanation.

Hey, you guys gonna have a section (on the site) on different cams and the performance gains they provide on our cars. That would be nice for the FAQ's!
 

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Yeah we'll try and get as much info up on the site for everyone. It's just going to take some time. There is alot to cover.

BTW here is a pic of my car on the dyno that Brian was talking about.

 

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I installed an intake cam out of an earlier motor into my car. The difference is the cam and head design between the earlier and later motors. It appears as though Nissan tuned down the cams, but found hp elsewhere to keep the 140hp figure (I think this may have been done to improve emissions). With the more aggressive cam, and the low port head, expect to gain about 4-6whp peak, and as much as 10whp peak, maybe more (or less, depending on teh motor). I gained about 3 peak hp (although it was on a different dyno :( so it's hard to tell the exact figure.) and almost 11hp at redline. Seat of the pants it felt like even more power and it very well might be, due to differences in the two dynos that negatively affected the power gains. But... it does gain power either way, and it does make the car faster. I gained between 2 and 3 mph in the 1/4 mile from this one upgrade. I now can trap at right under 92mph consistantly, that's pretty respectable for a relatively heavy (compared to an SE-R) G20.
I installed the cam and had some help doing this write-up for Nissan Performance Magazine (thanks guys =) ) .
91 Intake Cam install.
 

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Okay so they changed the head design on the lowports to compensate. Damn I was hoping it was just your ECU so alot of us P10 guys got screwed out of potential cheap HP.
 

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UltraOrange said:
Okay so they changed the head design on the lowports to compensate. Damn I was hoping it was just your ECU so alot of us P10 guys got screwed out of potential cheap HP.

No, stock you still make the same power... if you study highport vs. lowport dyno graph shapes, you'll notice that from the factory highport cars usually make more top end power, because the power doesn't drop off quite as fast. The lowports have a different head and intake manifold design to compensate for the smaller cams (which were changed to help with emissions in the later years). Stock you have more hp, modified (which most people don't do) the lowport w/ a highport cam might make a hair more hp. But it really depends on which two specific motors you're trying to compare. Each one is going to vary as well.
 

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We never bothered to establish if JKdonger has a high or low-port engine. The odds are good, though, that he actually has a high-port engine, and this thread (though not topic) is pointless. :)
 

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Hey buddy I was already commenting on the change in head design a simple yes or no would have sufficed s to if the head design had changed to compensate like I thought it had.

So where is this guy that started the thread??
 

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Yes, the head changed. That's where the terms "low-port" and "high-port" come from; the location of the intake ports on the head itself. The intake manifold on the low-ports also have longer, narrower runners, which (theoretically) improves the torque potential in lower RPMs.
 
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