SR20DET differences

[doridoridori]

Ok so I'm trying to do a bit of research before I get my hands dirty. I hope I don't get hell for this post being new to the forum I just want to make sure I go with the right SR ahead of time. So there's the S13/S14/S15 and each came with an SR, I'm aware there's a Redtop and Blacktop. Did each model come with a Redtop and Blacktop? also do the blacktops make that much more power than Redtops? and what's about the limit (hp/tq) a stock motor can hold safely before needing to build the motor more?

thanks any help/info is much appreciated

my apologies in advance if this has been covered before I just couldn't find the info I was looking for.

[JBB]

http://en.wikipedia.org/wiki/Nissan_SR20DET

http://zilvia.net/f/showthread.php?t=181106

http://zilvia.net/f/showthread.php?t=62607

http://forums.nicoclub.com/s13-red-t...es-t59346.html

http://www.nicoclub.com/archives/how...0det-head.html

http://www.sr20forum.com/archive/ind.../t-158977.html

http://www.nissansilvia.com/forums/i...owtopic=100572

http://www.nissanforums.com/sr20de-d...fferences.html

http://www.driftstl.com/forums/showt...s-Red-Top-Sr20

http://www.240sxforums.com/forums/s1...p-sr20det.html

http://forums.mightycarmods.com/show...op-differences

http://forum.s15oc.com/threads/6966-...et-differences

[bmxer882x]

before the flaming there is
s13 redtop (first motor) comes with a journal bearing t25 which puts out mabye 200 to the wheels.
s13 blacktop (all blacktops from here on) same as above just a tad newer as they were the second generation
s14 has a beefier t28 journal bearing and vvti produces 240ish? stock
s15 has a even better t28 dual ball bearing turbo vvti and larger injectors (turbo and injector size matters on model of s15 tho autos came with journal turbo)

thats a quick review to get you started.

[Kaifd3s]

Oh jesus...Let it begin.

[bmxer882x]

Holy cow didn't see the link message before mine. That's already starting it off good.

[doridoridori]

Originally Posted by bmxer882x

before the flaming there is
s13 redtop (first motor) comes with a journal bearing t25 which puts out mabye 200 to the wheels.
s13 blacktop (all blacktops from here on) same as above just a tad newer as they were the second generation
s14 has a beefier t28 journal bearing and vvti produces 240ish? stock
s15 has a even better t28 dual ball bearing turbo vvti and larger injectors (turbo and injector size matters on model of s15 tho autos came with journal turbo)

thats a quick review to get you started.

thanks very much that simplifies it enough for me, i'll do my research on the links above. So I assume it's true that the S13 redtop can potentially be as fast as a blacktop or best to just start off with a blacktop that has more potential? I'd like 350-400whp at most

[Fuego]

You should differentiate by chassis instead of color. You can build anything and make gobs of power. Do some more research and find what mods will get you what power.

[doridoridori]

Originally Posted by Fuego

You should differentiate by chassis instead of color. You can build anything and make gobs of power. Do some more research and find what mods will get you what power.

good point it's going into an 80s toyota should be pretty damn fast in stock form i'd imagine, just wanted to see the best option to go with if i wanted more power later

[bmxer882x]

I have a redtop
All support roughly same power of about 400 bottom end so if u want a bigger turbo which u will and want cams most cams delete vvti and turbo doesn't matter go with a s13 motor. Red or black. Blacks a tad newer but in the end it's just a color

[dorkidori_s13]

ugh, before this thread goes to hell...

SR20det Redtop 1st Gen: 90.5 to 91 (180sx and Silvia) NO HEAD FINS - T25 Turbo
SR20det Redtop 2nd Gen: 92 to 93 (180sx and Silvia) HEAD FINS - T25 Turbo
SR20det Blacktop 1st Gen: 94-95 (180sx only) HEAD FINS - T25 Turbo
SR20det Blacktop 2nd Gen: 96-98 (180sx and SilEighty only) HEAD FINS - T25 Turbo

Im not 100% on the changes between the 1st gen and 2nd gen Blacktop motors. From what I can recall, 1st gen used a slightly different tune in the ECU and I THINK grounded the 02 sensor on the chassis instead of inside the ECU like the late models did.

SR20det NOTCHTOP 1st Gen: 94-98 (S14 ONLY) VVT Intake cam - T28 w/journal bearing
SR20det NOTCHTOP 2nd Gen: 99-02 (S15 ONLY) VVT Intake cam - T28 w/dual ball bearing on R-Spec trim only

S15 R-Spec models came with a dual ball bearing GT28rs turbo that upped the power from 228hp to i believe 250.

All internals on SRs are the same for the most part. The heads between the VVT and non VVT engines have slightly different water way paths going from the block to the head. The S14/S15 use high mount intake manifold vs the S13 motors using the older low port manis. This was changed mainly due to emissions. (S13 AIV vs S14/S15 EGR)

No motor is superior than the other. They all have their ups and downs. Spend the money, build a motor correctly and have it tuned properly otherwise youll wind up with a very expensive and very unreliable pain in the ass! Most people shoot for the magical 400-500hp range for some odd reason. Unless youre building a full on track machine that isnt all hellastupid with ugly stretched wheels mounted on heavy ass, cheap wheels, 300whp in an S13 or S14 is damn scary! im not talking about 300 crank HP either. S-Chassis get dangerous after 300whp as keeping the rear end planted requires REAL wheels with REAL tires, not the trendy 225 on a 18x10 with no contact patch because your camber is at -12 degrees. Get an SR and start tuning it properly. When you hit the 300+whp mark, learn how to drive and properly tune the suspension in your car. racecars are lowered, not dumped. they use proper toe and camber, not the jack ass shit you see on cars that are all show and no go!

Also, S14/S15 motors ARE NOT called Blacktops! PERIOD! The proper name for them is NOTCHTOP because of the large hump in the middle of the valve cover. Nissan decided to incorporate the S13s OEM oil catch can into the valve cover instead of mounting it to the head of the motor above the exhaust manifold.

Im giving this thread 24 hours until it requires me to lock it due to the flame war that Im just waiting to errupt!

[doridoridori]

Originally Posted by dorkidori_s13

ugh, before this thread goes to hell...

SR20det Redtop 1st Gen: 90.5 to 91 (180sx and Silvia) NO HEAD FINS - T25 Turbo
SR20det Redtop 2nd Gen: 92 to 93 (180sx and Silvia) HEAD FINS - T25 Turbo
SR20det Blacktop 1st Gen: 94-95 (180sx only) HEAD FINS - T25 Turbo
SR20det Blacktop 2nd Gen: 96-98 (180sx and SilEighty only) HEAD FINS - T25 Turbo

Im not 100% on the changes between the 1st gen and 2nd gen Blacktop motors. From what I can recall, 1st gen used a slightly different tune in the ECU and I THINK grounded the 02 sensor on the chassis instead of inside the ECU like the late models did.

SR20det NOTCHTOP 1st Gen: 94-98 (S14 ONLY) VVT Intake cam - T28 w/journal bearing
SR20det NOTCHTOP 2nd Gen: 99-02 (S15 ONLY) VVT Intake cam - T28 w/dual ball bearing on R-Spec trim only

S15 R-Spec models came with a dual ball bearing GT28rs turbo that upped the power from 228hp to i believe 250.

All internals on SRs are the same for the most part. The heads between the VVT and non VVT engines have slightly different water way paths going from the block to the head. The S14/S15 use high mount intake manifold vs the S13 motors using the older low port manis. This was changed mainly due to emissions. (S13 AIV vs S14/S15 EGR)

No motor is superior than the other. They all have their ups and downs. Spend the money, build a motor correctly and have it tuned properly otherwise youll wind up with a very expensive and very unreliable pain in the ass! Most people shoot for the magical 400-500hp range for some odd reason. Unless youre building a full on track machine that isnt all hellastupid with ugly stretched wheels mounted on heavy ass, cheap wheels, 300whp in an S13 or S14 is damn scary! im not talking about 300 crank HP either. S-Chassis get dangerous after 300whp as keeping the rear end planted requires REAL wheels with REAL tires, not the trendy 225 on a 18x10 with no contact patch because your camber is at -12 degrees. Get an SR and start tuning it properly. When you hit the 300+whp mark, learn how to drive and properly tune the suspension in your car. racecars are lowered, not dumped. they use proper toe and camber, not the jack ass shit you see on cars that are all show and no go!

Also, S14/S15 motors ARE NOT called Blacktops! PERIOD! The proper name for them is NOTCHTOP because of the large hump in the middle of the valve cover. Nissan decided to incorporate the S13s OEM oil catch can into the valve cover instead of mounting it to the head of the motor above the exhaust manifold.

Im giving this thread 24 hours until it requires me to lock it due to the flame war that Im just waiting to errupt!

Thank you very much for the info. Also I've been in a few 500+whp cars so it's nothing new, I've been drifting for a good while but wanted to try this hybrid setup to make a beast of a car. Of course there's always room to learn and this is why I wanted to see what I could do with an SR. Also another thing the "Blacktop" I've heard that multiple times from many 240 guys but if I've heard wrong my apologies. Once again thanks for the info I'll copy all of it and save it to my computer and start to do a build soon. This won't be going into an S-Chassis it'll be going into an 80's corolla so im sure the 300+whp will be ridiculous enough. I just didn't want to go into this build blindly. It's pretty easy to find the Redtops for dirt cheap and i'll see what I need to do, to build a motor to reliably hold 300ish whp in a 2000lb car it should be pretty fun I can't wait.

[JBB]

usually dirt cheap does not equal quality. just make sure the compression is pretty even across the board and everything is included (some shops try to sell the motors with missing ECU, wire harness, MAF, or igniter chip, etc). I paid 2300 for my red top fyi, but the compression was in the 170's and only off by 1 or 2 psi each cylinder

[TheRealSy90]

Redtop, t28, injectors, rom tune, fmic, exhaust. 300whp done.

Stock for stock notchtop motors are better. If you are going to mod it at all I always recommend an s13 red/black for simplicity.

[doridoridori]

Originally Posted by JBB

usually dirt cheap does not equal quality. just make sure the compression is pretty even across the board and everything is included (some shops try to sell the motors with missing ECU, wire harness, MAF, or igniter chip, etc). I paid 2300 for my red top fyi, but the compression was in the 170's and only off by 1 or 2 psi each cylinder

very true I just meant dirt cheap in terms of finding a complete motor, I'd rebuild it as soon as I got it I never install/run any motor if I'm unaware of it's history definitely learn from others mistakes seen that one too many times, seen ppl drop motors in only to pull them 6months or a year maybe down the line.

[mewantkouki]

There are three different types of S14/S15 sr engines.

Zenki s14 sr have smooth casting on the front of the head.

Kouki s14 sr have heat sink fins cast into the front of the head.

S15 sr look identical to late model s14 sr, however they use valve cover bolts like p11/p12 sr20ve versus the stud / nut combination on earlier sr20det engines. The valve covers are also different because of the different coil packs (built in ignitor)

[Kingtal0n]

95-96 Zenki SR20DET Notchtop comes with WC ECU and T-28 Ball Bearing turbocharger
97-98 Kouki SR20DET Notchtop comes with NA ECU and T-28 Ball Bearing turbocharger


I have seen the T-28 journal bearing model you spoke of, but never from an JDM sr20det RWD version notchtop before. I've pulled apart at least 40 notch tops in the last 10 years and always found a ball bearing turbocharger attached. The S15 model is identical save for the exhaust wheel being made of inconel iirc. I've made 300rwhp (dynojet) with both models.

somewhere between 95 and 96.5 they went from a red WC ECU to a black WC ecu. same plug connector though. the NA ecu I have only seen on 98 kouki models, the plug is different.

After doing a hundred swaps I highly recommend avoiding the S13 model engines (as of 2009). You can current source a complete S14 sr20det swap for around $2500 and have it running/driving for $3000.
S15 can be done right now for about $3900 including differential/driveshaft.

The 6-speed circlip issue makes me weary of S15 swaps but none of the cars I've been around has ever failed a box because of it. nevertheless...
http://forum.s15oc.com/threads/8193-...hlight=circlip

Originally Posted by I-nearly-bought-a-batty

Well I bought my car with less than 40,000km's (genuine k's / NZ new) and have never clutch kicked it. I don't dump the clutch and run a stock driveline; power is 210rwkw. I never apply full power until my engine oil temp gauge reads normal operating temp; and treat my gearbox with respect. I also use quality synthetic oils in my driveline. I also know how to shift gears properly without missing shifts and graunching gears. However at 73,000ks it shat itself whilst I changed from 4th to 5th. So it boils down to a matter of "when" rather than "if". RX7 owners bank on replacing engines; and we bank on replacing gearboxes. I've just paid my dues so I get to play for another 70,000k's. It's definitely not cheap retaining the 6spd; but I prefer to keep the car original in that sense.

[jr_ss]

The S13 DET's are high port heads, S14/15DET's are low port heads, regardless of the intake manifold configuration.

hey guys, i was thinking....

which motor is better, my LFA v10 or kouki 180SX SR20DET?

im thinking i should pull the v10 setup and go back to sr20det. any advice?

[Matej]

Originally Posted by ixfxi

hey guys, i was thinking....

which motor is better, my LFA v10 or kouki 180SX SR20DET?

im thinking i should pull the v10 setup and go back to sr20det. any advice?

It depends on your priorities. Obviously the SR20 will be easier to work on.

[jr_ss]

Originally Posted by ixfxi

hey guys, i was thinking....

which motor is better, my LFA v10 or kouki 180SX SR20DET?

im thinking i should pull the v10 setup and go back to sr20det. any advice?

We need pictures, because I don't understand the question...

[hobbs]

Originally Posted by dorkidori_s13

SR20det NOTCHTOP 1st Gen: 94-98 (S14 ONLY) VVT Intake cam - T28 w/journal bearing
SR20det NOTCHTOP 2nd Gen: 99-02 (S15 ONLY) VVT Intake cam - T28 w/dual ball bearing on R-Spec trim only

S15 R-Spec models came with a dual ball bearing GT28rs turbo that upped the power from 228hp to i believe 250.

The S14 SR20DET VVT used a ball bearing turbo charger which is the equivalent to the turbo used on the S15 SR20DET when equipped with an automatic transmission. The bump in HP with the S15 motors came from an increased boost pressure, larger injectors and revised camshafts, not the turbo charger.

Originally Posted by dorkidori_s13

All internals on SRs are the same for the most part. The heads between the VVT and non VVT engines have slightly different water way paths going from the block to the head. The S14/S15 use high mount intake manifold vs the S13 motors using the older low port manis. This was changed mainly due to emissions. (S13 AIV vs S14/S15 EGR)!

This is also incorrect, S13 SR20s are considered highports and the S14/S14 SR20s are considered lowport head designs. This was NOT changed due to emissions, it was a better flowing head design along with a better flowing intake manifold.

All SR20 internals are NOT the same and it is generally regarded that the S14/S15 motors are vastly superior to the S13 SR20 motors. For instance Nissan had revised the following items on the S14/S15 motors:

- New head and intake manifold design
- Revised valve cover and PCV system
- Revised EGR setup
- Revised IACV system
- Revised oil pickup and strainer
- Revised timing chain guides
- Revised turbo manifold and O2 housing
- Revised turbocharger exhaust housing (S15R)
- Revised coilpacks (S15)
- Revised camshafts for VVT
- Revised water outlet
- Revised oil pump

S14/S15 motors tend to make more torque down low due to the head/intake manifold design and with the use of VVT. Nissan also switched from the older highport head design to lowport head design in 94 for all USDM models aswell - B14/P10 93.5 models. If you're going to spend the money I would pickup a S14/S15 motorset over a S13 any day of the week.

[dorkidori_s13]

Originally Posted by hobbs

This is also incorrect, S13 SR20s are considered highports and the S14/S14 SR20s are considered lowport head designs. This was NOT changed due to emissions, it was a better flowing head design along with a better flowing intake manifold.

thank you, i tend to get the two mixed up in exactly how theyre referred to. i usually just say they changed the intake manifold design.

All SR20 internals are NOT the same and it is generally regarded that the S14/S15 motors are vastly superior to the S13 SR20 motors. For instance Nissan had revised the following items on the S14/S15 motors:

- New head and intake manifold design
- Revised valve cover and PCV system
- Revised EGR setup
- Revised IACV system
- Revised oil pickup and strainer
- Revised timing chain guides
- Revised turbo manifold and O2 housing
- Revised turbocharger exhaust housing (S15R)
- Revised coilpacks (S15)
- Revised camshafts for VVT
- Revised water outlet
- Revised oil pump

S14/S15 motors tend to make more torque down low due to the head/intake manifold design and with the use of VVT. Nissan also switched from the older highport head design to lowport head design in 94 for all USDM models aswell - B14/P10 93.5 models. If you're going to spend the money I would pickup a S14/S15 motorset over a S13 any day of the week.

i wasnt trying to get that technical with the post as the OP didnt really seem to require said knowledge. i just threw some of the more common things out there.

im going to argue with you though about the S14/S15 motorset vs S13 motorset. between the 2, there is no major reason one is better than the other. that actually sounds like a very n00b and opinionated comment to me (although im sure youll go off on some tangent as you seem to like to try and piss me off lately as it is). both motors are easily built to the same numbers, and most of the major builds ive seen from major japanese and american tuners tend to utilize S13 motors over S14/S15 motors. but most major japanese tuners leave whatever motor is in the car where it belongs and work with what they have.

but to each his own. if youre going to build an SR (or any motor), just spend the money and do it right instead of half assing it with knock off and cheap parts like most people do today.

[azndan2]

Originally Posted by ixfxi

hey guys, i was thinking....

which motor is better, my LFA v10 or kouki 180SX SR20DET?

im thinking i should pull the v10 setup and go back to sr20det. any advice?

Do you think you're cool or something?

[hobbs]

Originally Posted by dorkidori_s13

im going to argue with you though about the S14/S15 motorset vs S13 motorset. between the 2, there is no major reason one is better than the other. that actually sounds like a very n00b and opinionated comment to me .

As the OP was asking about stock motors, I would say there are a couple of major reasons the S14/S15 motorsets are better than S13 motor sets:

- Better flowing head and intake manifold - Sure you can build a S13 for the same numbers as a S14/S15 motor but at what cost? Why not start out with something that is great rather than something that is 'OK'
- Better lubrication system - Nissan revised almost the entire lubrication system on the notchtop, there's a reason why they updated it on their more powerful motorsets.
- Age - Even at the latest production dates the S15 motorset is 5 years NEWER than a 1998 S13 blacktop, if you're keeping it stock inside why wouldnt you want a newer motor?

What it all boils down to is cost, people seem to think we'll they are both SR20s and they can both make 400whp on stock internals so I'll just go with the cheaper motorset. How and when they make that 400whp is very different from eachother, save pennies just to spend a dollar.

It's common to see people just shooting for peak power these days with little care for how everything plays together to create a nice graph on a dyno, I guess it's just too complicated for some.

Originally Posted by azndan2

Do you think you're cool or something?

I think you missed something.

[dorkidori_s13]

Originally Posted by hobbs

As the OP was asking about stock motors, I would say there are a couple of major reasons the S14/S15 motorsets are better than S13 motor sets:

- Better flowing head and intake manifold - Sure you can build a S13 for the same numbers as a S14/S15 motor but at what cost? Why not start out with something that is great rather than something that is 'OK'
- Better lubrication system - Nissan revised almost the entire lubrication system on the notchtop, there's a reason why they updated it on their more powerful motorsets.
- Age - Even at the latest production dates the S15 motorset is 5 years NEWER than a 1998 S13 blacktop, if you're keeping it stock inside why wouldnt you want a newer motor?

What it all boils down to is cost, people seem to think we'll they are both SR20s and they can both make 400whp on stock internals so I'll just go with the cheaper motorset. How and when they make that 400whp is very different from eachother, save pennies just to spend a dollar.

It's common to see people just shooting for peak power these days with little care for how everything plays together to create a nice graph on a dyno, I guess it's just too complicated for some.

im curious, has anyone really ever documented the differences in the 4 generations of S13 SRs? and im talking about more than just "oh, the 02 sensor is a different and the ECU has a different letter on the cover". the more ive been reading about and investigating the various generations of S13s (180sx and Silvia) the more im finding that nissan kept working on and improving the s13 SR thru time.

what i do know about the 4 different SRs...

• There are 4 different generations of SRs
- 90 thru 92 (1st gen Redtop)
- 93 thru 94 (2nd gen Redtop)
- 94 thru 95 (3rd gen Blacktop)
- 96 thru 98 (4th gen Blacktop)
• 1st and 2nd gen redtop grounded 02 sensor to chassis
• 3rd and 4th gen blacktop grounded 02 sensor to harness
• 1st and 2nd gen used skinny 02 sensors
• 3rd and 4th gen used fat 02 sensors
• 4th gen blacktop used a brand new ECU that no previous gen used
• 1st gen redtop has a flat faced head near the front cam seals
• 2nd, 3rd and 4th gen has fins on the head near front cam seals
• S13 Silvia only used 1st gen SR
• 180sx used every generation
• 180sx 97-98 Kouki Type R used a supposedly used a slightly different ecu/wiring harness than Type X
• SilEighty ECU was tuned for 3-4 more lbs of boost

thats about all i can think of. but i would love to see if someone has documented the differences between all generations of the S13 SR as nissan did improve the motor over time with the Type X/Type R Kouki 180s having the most revised tuning done on them.

[KiLLeR2001]

Originally Posted by dorkidori_s13

ugh, before this thread goes to hell...

Hmm. A lot of this information is false, so I will correct you accordingly.

Originally Posted by dorkidori_s13

SR20det Redtop 1st Gen: 90.5 to 91 (180sx and Silvia) NO HEAD FINS - T25 Turbo
SR20det Redtop 2nd Gen: 92 to 93 (180sx and Silvia) HEAD FINS - T25 Turbo
SR20det Blacktop 1st Gen: 94-95 (180sx only) HEAD FINS - T25 Turbo
SR20det Blacktop 2nd Gen: 96-98 (180sx and SilEighty only) HEAD FINS - T25 Turbo

SR20det NOTCHTOP 1st Gen: 94-98 (S14 ONLY) VVT Intake cam - T28 w/journal bearing
SR20det NOTCHTOP 2nd Gen: 99-02 (S15 ONLY) VVT Intake cam - T28 w/dual ball bearing on R-Spec trim only

S13 Redtop SR20DET is from 01/91 to 12/93. No head fins and T25 journal bearing.
S13 Blacktop SR20DET Gen 1. is from 01/94 to 07/96. Head fins, T25 journal bearing.
S13 Blacktop SR20DET Gen 2. is from 08/96+. Head fins, T25 journal bearing.

Gen 2. blacktop has a different wiring harness configuration and ECU pinout. There may be other minor differences but nothing of significance.

S14 Notchtop SR20DET Gen 1. from 10/93 to 05/96, VVT T28 ball bearing Part #: 14411-69F00
S14 Notchtop SR20DET Gen 2. from 06/96+, VVT T28 ball bearing Part #: 14411-69F00

I don't know every difference between the two gen's for the S14 notchtop but it appears different hardware was used for certain things.

S15 Notchtop SR20DET from 01/99+, VVT, different coilpack configuration from previous motors, T28 (GT2560R to be exact) Spec-R turbo was ball bearing Part #: 14411-91F00, T28 with journal bearing Part #: 14411-75F00

They stopped producing the ball bearing turbo on 10/00, so any Spec-R after that date will have a journal bearing T28. Automatic S15's had the old S14 ball bearing turbo part number: 14411-69F00 up until 10/00. After 10/00 all models switched to the journal bearing T28.

[dorkidori_s13]

I know for a fact that there was a redtop with headfins as i owned one. It came in a front clip from a 180sx that was dated 1993 on the vin tag. The ecu was the redtop ecu and not the blacktop ecu. I got the motor back in 2004 as my first sr swap. still have pics if ud like me to post. I owned the motor for over 5 years and put over 60,000 miles on it. Great engine!

[Fuego]

Originally Posted by dorkidori_s13

I know for a fact that there was a redtop with headfins as i owned one. It came in a front clip from a 180sx that was dated 1993 on the vin tag. The ecu was the redtop ecu and not the blacktop ecu. I got the motor back in 2004 as my first sr swap. still have pics if ud like me to post. I owned the motor for over 5 years and put over 60,000 miles on it. Great engine!

I also own a redtop with fins.

[KiLLeR2001]

Looks like you guys are both victims of a head swapped redtop.



As you can see, no year changes in the head design as you are stating. 01/91 to 01/94 and then 01/94+.

[dorkidori_s13]

my motor wasnt head swapped. my clip had about 16,000 miles on it and was bone stock (no FMIC, no upgraded BOV, no boost controller, no signs of any abuse, NOTHING). i highly doubt the headgasget was blown in that short amount of time that would warrant a head swap instead of machining the head.

nissan may have never changed the actual part number as outside of the fins, nothing actually changed about the head. theyve done this in the past with tons of parts. for example (in my own findings thru the years) the timing chain guides for the KA that were notorious for shattering changed their design but never changed their part number. the metal seals i recently changed out on my turbo elbow (the part that bolts to the hot pipe) changed design but never changed part number. the metal gasket that seals the turbo to the manifold changed its design slightly but never changed its part number.

ive seen quite a few redtop motors with fins and without fins. all of the finned motors were redtop ECUs, never had a head swap, were all low milage and all dated 93-94.