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Discussion Starter · #1 · (Edited)
Hey all,

I just acquired a Datsun Roadster with a 1994 S13 KA24DE manual. I've searched many of the various forums regarding the infamous 248 cam swaps. Most of them have lots of information but not much data. I did do a search on this forum and ran across this Sticky but didn't want to add onto it: KA24DE N/A Cam upgrade guide. Another great one from this forum was 248 degree exhaust cam on intake side Q. Other forums like KA-T.org, NICO, zilvia.net were also great resources.

The main site that was extremely helpful was from DriftKat.com. by Alkemyst This site has ALL the KA24DE cam permutations you can think of as well as the ability to ADV or RET the timing.

From reading all the forums I've gleaned a few insightful tid-bits.
1) A few people pioneered the OEM cam swap and they should get credit! Thank you.
2) A lot of people jumped on the band wagon not understanding cam design and flamed them for no reason. Shame on you.
3) If databases like DriftKat were around in 2005, there would have been less mistakes and bickering.

Data heavy post below:

So what I've done is laid out some of the major OEM S13/S14 KA24DE cam combinations you typically see people do. I did not do any other (Altima/Frontier combo's because that's not what I have).

First set are STOCK setups. This data is very important as this is your base, ALL other combinations will be of some derivation/deviation from these setups. As always, performance using off the shelf OEM cams only move the power around, you do not 'gain' HP or TQ. You move the peak power around the RPM range.

Intake91-93 S13, 240*94 S13, 240*95-98 S14, 232*
Exhaust91-93 S13, 248*94 S13, 248*95-98 S14, 232*
Intake Duration: 240ºIntake Duration: 240ºIntake Duration: 232º
Intake Open BTDC(-ATDC): -1ºIntake Open BTDC(-ATDC): -1ºIntake Open BTDC(-ATDC): -1º
Intake Close ABDC: 61ºIntake Close ABDC: 61ºIntake Close ABDC: 53º
Intake Centerline: 121ºIntake Centerline: 121ºIntake Centerline: 117º
Intake AdjustmentIntake Timing: 0ºIntake Timing: 0ºIntake Timing: 0º
Lobe Separation: 120.5ºLobe Separation: 118.5ºLobe Separation: 114.5º
Exhaust Duration: 248ºExhaust Duration: 248ºExhaust Duration: 232º
Exhaust Open BBDC: 64ºExhaust Open BBDC: 60ºExhaust Open BBDC: 48º
Exhaust Close ATDC (-BTDC): 4ºExhaust Close ATDC (-BTDC): 8ºExhaust Close ATDC (-BTDC): 4º
Exhaust Centerline: 120ºExhaust Centerline: 116ºExhaust Centerline: 112º
Exhaust AdjustmentExhaust Timing: 0ºExhaust Timing: 0ºExhaust Timing: 0º
Overlap: 3ºOverlap: 7ºOverlap: 3º

The S13 248 exhaust cam is the biggest variable that I can see when people grab them and put them as their intake cam. The intake for all S13 is the same, BUT there is a 4* difference between the 91-93 vs 94 year exhaust cams. Knowing which year S13 KA24DE exhaust cam you're using can have massive affect on your outcome! Your lobe separation as well as overlap change which directly affect where your peak power band will lay.

Intake91-93 S13, 240*94 S13, 240*
Exhaust94 S13, 248*91-93 S13, 248*
Intake Duration: 240ºIntake Duration: 240º
Intake Open BTDC(-ATDC): -1ºIntake Open BTDC(-ATDC): -1º
Intake Close ABDC: 61ºIntake Close ABDC: 61º
Intake Centerline: 121ºIntake Centerline: 121º
Intake AdjustmentIntake Timing: 0ºIntake Timing: 0º
Lobe Separation: 118.5ºLobe Separation: 120.5º
Exhaust Duration: 248ºExhaust Duration: 248º
Exhaust Open BBDC: 60ºExhaust Open BBDC: 64º
Exhaust Close ATDC (-BTDC): 8ºExhaust Close ATDC (-BTDC): 4º
Exhaust Centerline: 116ºExhaust Centerline: 120º
Exhaust AdjustmentExhaust Timing: 0ºExhaust Timing: 0º
Overlap: 7ºOverlap: 3º

Here is the 248/248 combo with zero adjustments.

Intake91-93 S13, 248*94 S13, 248*91-93 S13, 248*94 S13, 248*
Exhaust91-93 S13, 248*91-93 S13, 248*94 S13, 248*94 S13, 248*
Intake Duration: 248ºIntake Duration: 248ºIntake Duration: 248ºIntake Duration: 248º
Intake Open BTDC(-ATDC): 1.7ºIntake Open BTDC(-ATDC): -2.3ºIntake Open BTDC(-ATDC): 1.7ºIntake Open BTDC(-ATDC): -2.3º
Intake Close ABDC: 66.3ºIntake Close ABDC: 70.3ºIntake Close ABDC: 66.3ºIntake Close ABDC: 70.3º
Intake Centerline: 122.3ºIntake Centerline: 126.3ºIntake Centerline: 122.3ºIntake Centerline: 126.3º
Intake AdjustmentIntake Timing: 0ºIntake Timing: 0ºIntake Timing: 0ºIntake Timing: 0º
Lobe Separation: 121.15ºLobe Separation: 123.15ºLobe Separation: 119.15ºLobe Separation: 121.15º
Exhaust Duration: 248ºExhaust Duration: 248ºExhaust Duration: 248ºExhaust Duration: 248º
Exhaust Open BBDC: 64ºExhaust Open BBDC: 64ºExhaust Open BBDC: 60ºExhaust Open BBDC: 60º
Exhaust Close ATDC (-BTDC): 4ºExhaust Close ATDC (-BTDC): 4ºExhaust Close ATDC (-BTDC): 8ºExhaust Close ATDC (-BTDC): 8º
Exhaust Centerline: 120ºExhaust Centerline: 120ºExhaust Centerline: 116ºExhaust Centerline: 116º
Exhaust AdjustmentExhaust Timing: 0ºExhaust Timing: 0ºExhaust Timing: 0ºExhaust Timing: 0º
Overlap: 5.7ºOverlap: 1.7ºOverlap: 9.7ºOverlap: 5.7º

Here is the 248/232 combo with zero adjustment.

Intake91-93 S13, 248*94 S13, 248*
Exhaust95-98 S14, 232*95-98 S14, 232*
Intake Duration: 248ºIntake Duration: 248º
Intake Open BTDC(-ATDC): 1.7ºIntake Open BTDC(-ATDC): -2.3º
Intake Close ABDC: 66.3ºIntake Close ABDC: 70.3º
Intake Centerline: 122.3ºIntake Centerline: 126.3º
Intake AdjustmentIntake Timing: 0ºIntake Timing: 0º
Lobe Separation: 117.15ºLobe Separation: 119.15º
Exhaust Duration: 232ºExhaust Duration: 232º
Exhaust Open BBDC: 48ºExhaust Open BBDC: 48º
Exhaust Close ATDC (-BTDC): 4ºExhaust Close ATDC (-BTDC): 4º
Exhaust Centerline: 112ºExhaust Centerline: 112º
Exhaust AdjustmentExhaust Timing: 0ºExhaust Timing: 0º
Overlap: 5.7ºOverlap: 1.7º

This next set of cams are your 248/248 and 248/232 mutants. This data has been adjusted to keep the 1ATDC & 7* Overlap that Nissan engineers used. These combinations are only achieved by an adjustable cam gear. I know the JWT drilled one will get you close, but the Tomei one is will get you precise adjustments. Obviously, you can ADV/RET the intake and exhaust cams all you want using the DriftKat tool and inputting which cam you'd like to use to approximate the performance.

Here are the 248/248 combos all together using adjustable cam gears. As you can see, depending on the year 248 exhaust cam, you ADV or RET differently.

Intake91-93 S13, 248*94 S13, 248*91-93 S13, 248*94 S13, 248*
Exhaust91-93 S13, 248*91-93 S13, 248*94 S13, 248*94 S13, 248*
Intake Duration: 248ºIntake Duration: 248ºIntake Duration: 248ºIntake Duration: 248º
Intake Open BTDC(-ATDC): -1ºIntake Open BTDC(-ATDC): -1ºIntake Open BTDC(-ATDC): -1ºIntake Open BTDC(-ATDC): -1º
Intake Close ABDC: 69ºIntake Close ABDC: 69ºIntake Close ABDC: 69ºIntake Close ABDC: 69º
Intake Centerline: 125ºIntake Centerline: 125ºIntake Centerline: 125ºIntake Centerline: 125º
Intake AdjustmentIntake Timing: 2.7º retardedIntake Timing: 1.3º advancedIntake Timing: 2.7º retardedIntake Timing: 1.3º advanced
Lobe Separation: 120.5ºLobe Separation: 120.5ºLobe Separation: 120.5ºLobe Separation: 120.5º
Exhaust Duration: 248ºExhaust Duration: 248ºExhaust Duration: 248ºExhaust Duration: 248º
Exhaust Open BBDC: 60ºExhaust Open BBDC: 60ºExhaust Open BBDC: 60ºExhaust Open BBDC: 60º
Exhaust Close ATDC (-BTDC): 8ºExhaust Close ATDC (-BTDC): 8ºExhaust Close ATDC (-BTDC): 8ºExhaust Close ATDC (-BTDC): 8º
Exhaust Centerline: 116ºExhaust Centerline: 116ºExhaust Centerline: 116ºExhaust Centerline: 116º
Exhaust AdjustmentExhaust Timing: 4º advancedExhaust Timing: 4º advancedExhaust Timing: 0ºExhaust Timing: 0º
Overlap: 7ºOverlap: 7ºOverlap: 7ºOverlap: 7º

Here are the 248/232 combos adjusted with gears.

Intake91-93 S13, 248*94 S13, 248*
Exhaust95-98 S14, 232*95-98 S14, 232*
Intake Duration: 248ºIntake Duration: 248º
Intake Open BTDC(-ATDC): -1ºIntake Open BTDC(-ATDC): -1º
Intake Close ABDC: 69ºIntake Close ABDC: 69º
Intake Centerline: 125ºIntake Centerline: 125º
Intake AdjustmentIntake Timing: 2.7º retardedIntake Timing: 1.3º advanced
Lobe Separation: 116.5ºLobe Separation: 116.5º
Exhaust Duration: 232ºExhaust Duration: 232º
Exhaust Open BBDC: 44ºExhaust Open BBDC: 44º
Exhaust Close ATDC (-BTDC): 8ºExhaust Close ATDC (-BTDC): 8º
Exhaust Centerline: 108ºExhaust Centerline: 108º
Exhaust AdjustmentExhaust Timing: 4º advancedExhaust Timing: 4º advanced
Overlap: 7ºOverlap: 7º

More lobe separation angle means you get a bit more maxHP in the higher rpms but maxTQ at lower rpms and more flat. Tight lobe separation angle means you get less maxHP in lower rpms but more maxTQ sooner. It is a zero sum game, move the graphs up and down, left and right.
More overlap means more high-RPM power, less low-RPM power. Less overlap means more low-RPM power, less high-RPM power. I like more overlap for scavenging reasons.


Overall, its not as simple as just dropping in a cam. If you want to truly utilize the duration, lobe separation, and overlap of that $60 ebay cam... you gotta spend the money on adjustable cam gears. It's still cheaper than a set of performance cams that wont pass smog and move that powerband way out of normal street driving. If you want to just do the 248 3 or 4 teeth method and enjoy poor mpg but that lovely lope sound, go for it! It's your car, do what you want.

Obviously, this post is geared toward NA street vehicles. Obviously, I have not done these combination and am just plugging in data using a tool on the internet. Use this information at your own risk, I am not responsible for you messing up your motor.


Ben
 
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