Gen3 Debate

[keithlee21]

Gen III Differences

FYI: Gen III Differences
- MAP sensor instead of AFM
- Bosch D-Jetronic (Gen III) vs. L-Jetronic (relatively primitive) engine management
- CT20b turbo replaces CT26
- Boost raised from 10psi to 13psi
- Fuel cut raised from 12 psi to 18 psi
- Different ECU
- 4 wire O2 sensor
- Shim under bucket valve shims
- slightly more aggressive cams
- Revised internals (pistons, con-rods etc.)
- Revised cylinder head cooling passages/water jackets
- Revised intake manifold (8 'independent long ports' reduced to 4)
- intake manifold inlet air temperature sensor added. i.e. after turbo and intercooler.
- Revised gearbox with close ratio gearing
- lower compression ratio
- stainless steel head gasket
- factory 540cc injectors replace 430cc injectors
- revised fuel rail with bigger bore and relocated pressure regulator
- TVIS eliminated
- EGR eliminated
- LSD in 80% of them
- throttle body increased from 55mm to 60mm
- inlet valve lift increased from 8.2 to 8.7
- intake manifold inlet air temperature sensor added
- Less restrictive exhaust elbow
- Aluminum oil pan
- more rigid alloy sump and additional oil baffles
- Factory Catch can
- Better Oil Cooler and relocated oil filter (bottom)
- 4 Channel ABS coupled with Traction Control available
- No. 1 compression ring described as 'stainless steel' instead of just 'steel'. Oil ring is described as 'stainless steel' instead of 'a combination of steel and stainless steel'.
- The fuel pressure raised from 36 PSI (2.55 bar) to 41 PSI (2.9bar).

Gen III Debate

Now, there has been a lot of debate between the US spec engine and the Gen3 engine.

I have not been in the mr2 community for some time now. And, I have sold my car about 2 years ago. Since, then I've seen a lot of progression and development making the generations of the 3SGTE that much more reliable when increasing its power.

Now, my experiences and preferences for the building of my car may and, probably is very different from yours. Initially, when I bought my 93' MR2 I wanted to build something with huge power. And, within my own perception of power for the mr2 I succeeded with what I wanted but, also sacrificing 3 blown up US 3SGTE’s. Poor tuning on my part...all my fault. Thank god for tuning primers like RickyB now.

My new goals were to have something with great midrange power. I wanted to focus more on the throttle response and balance of the car rather than overpowering the platform. As many other high horsepower mr2 owners can attest to…flogging around a high horsepower mr2 is not the easiest thing to do.

I bought my Gen3 clip from Cartune in the City of Industry. They were able to locate and ship over the clip to my door. Now, to this day I’m not really sure what the clip had internally. What really surprised me after dropping in the clip was the amount of lowend grunt that the car had in the first 3 gears. I have a feeling that the previous owner of the clip in Japan must of swapped the ST185 1-3 gears into it while throwing in the KAAZ LSD. Hey, luck me!

Now, for the good part.

Was I ever completely satisfied with the Gen3? NO

Would I do it again? YES

Is there a better way of achieving the results? PROBABLY

These answers are probably very confusing to you. The Gen3 gave me almost everything that I could hope for with a complete drop in clip. I really did not have to touch it. But, that’s also considering that I did a basic intake, exhaust, and intercooler…plus, whatever the previous owner did prior to me receiving the clip. But, just as Ricky B pointed out the Gen3 was never meant to run in the US as you can see from the previous dyno plots. The Gen3 will run on 91 octane but, it definitely did not like it. There were the occasional hiccups from not being tuned. If I were to do this again I definitely would have thrown on some kind tuning parameter for the vehicle. At least that way I would not have to worry about the vehicle and it would have been even that much more reliable for me.

If I were to own another MR2 I would probably do it again. Many of your MR2 has approached and are probably over 150K mile mark by now. Transmission, engine components, sensors, wiring harness, etc have and/or are worn and tired by now. Now, a clip won’t give you new ones but, it will definitely give you items that have less mileage and years of wear. So, if you look at the whole picture you not only getting a newer engine and transmission but, also the components that come with the clip.

Now, is there a better way of achieving the same results I set out for? Most likely and probably. With the further progression and, development of research and products for the US 3SGTE it has show to be very capable and now reliable. Tuning is ‘THE ESSENTIAL INGREDIENT’ in the mix of attaining the goals of power for your vehicle. Even with the Gen3 it will need to be tuned to run reliably. But, the US engine can and will be able to give you the same results for cheaper.

Now, why did I drop in the Gen3? The most honest answer I can give you…Because I could. At the time I could afford it. So, why not? Why do Honda owners drop in JDM engines into their cars? Why do BMW and Porsche owners drop in Euro spec engines into their vehicles? Probably because enthusiasts and connoisseurs for the specific vehicle have a love and obsession for the history, development and, lineage of their vehicle. So, rather continuing to debate this topic…work on the development and tuning of both platforms. There is no real answer to this debate. It will not stop customers requesting more Gen3 clips and, dropping them into their cars. And, it will not stop the further development of US 3SGTE. Drop the debate.

[rhouck]

Nice article, thank you. However, I would say one big piece missing from your analysis is why someone should buy a Gen3 motor over a JDM Gen2 motor. A lot of your argument appears to revolve around the idea that a clip will give you newer lower mileage components.... but this will be the case with a Gen2 motor as well. So what needs to be answered is not USDM vs JDM, but JDM Gen2 vs JDM Gen3.

Now I would say the biggest reasons I would pick one over a Gen2 would be:
- ct20b: a stock turbo that completely transforms the driving experience; quite possibly the perfect turbo for 95% of owners and finally gives the MR2 the sports car performance feeling it should have had from the beginning
- no AFM
- 540 injectors w/ corresponding fuel rail

If I were to do it over again, I wish I had a Gen3 motor in my car versus the Gen2, especially as I already upgraded to a ct20b and now look to install a PowerFC, swap in larger injectors, etc

I will say the octane difference is an issue worth considering. In my experience, the motors do not really run correctly with less than 94 octane fuel.

[DavidV]

Excellent post, Keith. Stickied!

-- DavidV

[GReddySetGO]

I used to have a USDM turbo motor, and have since gotten a Gen3. I must say it was worth every penny, and if I had to do it all over again, I would go Gen3 first.

[blueprint]

I'm on the same boat as Danny (Greddysetgo).

I had my 91 USDM Turbo for since 2000 and the motor finally went out on me in 2004. I sold that car and purchased my friends 91T w/ Gen III and it was noticably faster than my old 91 and had less mods done to it.

My 91 USDM ran consistent low 14's each time i took it out and i've ran high 13's with my current MR2 with less mods.

[47mr2's]

I have owned several of each motors. I would have to say the gen3 is a much better motor than the gen2. As someone mentioned above the jdm gen2's will have low mileage, however their mileage most likely will not be as low as a gen3. Age tends to have more impact on most vehicles rather than mileage. I would rather have something that has been lightly used than something that has just sat. The gen3 has better performance with intake and exhaust than a gen2 with vpc, boost control, intercooler, flywheel, exhaust, and intake. It will also be far more reliable. I do feel the gen2 is a good motor but it requires a lot more tweaking with less reliability to get the power you can simply get from a gen 3 with intake and exhaust. If you are shooting for 400whp then it really doesn't matter where you start. Obviously the gen2 will be cheaper. It seems to me that most of the guys who talk down on the gen3 don't have one and have probably never driven one. They like to justify spending fortunes on their gen2 by saying the gen3 is not that great of a motor. A friend of mine spent 10k about 4 years ago on building his gen2. I tried to convince him otherwise and tried to talk him into going gen3. Needless to say he didn't listen. Obviously 4 years ago there weren't many EMS 's available. He had a vpc, SAFC, intercooler, 550cc injectors, supra fuel pump, JE pistons, Crower rods, ported head, Metal headgasket, jun flywheel, upgraded 57 trim ct26, upgraded valves, springs, retainers, gutted tvis basically most of the products available back then to run decent numbers. When all was said and done at 19 psi and 5000ft above sea level he ran a best of 13.5. I have not had my gen3 out to the track but my friend did. He ran a 13.2 with intake exhaust and intercooler @ 17psi on a gen3.

[MR2T32]

Gen3 is a nice motor, but i don't think it's that much better than a gen2 or even a gen1. I curently have a Gen1, i paid 2800 installed, w/ intake, exhaut, and EBC, and i'm running 14 flat at 15.5psi. Time slip is available upon request. Don't get my wrong, I like the stock performace Gen3 puts out, but let just just say a guy have 5k to spend, he can either get a Gen3 or get a Gen2 and have money left to upgrade to CT27 and maybe some other things. If we look at it that way, gen2 would be a better buy for the money. But that's just my opinion.

[Triad.:]

Originally Posted by MR2T32

...but let just just say a guy have 5k to spend, he can either get a Gen3 or get a Gen2 and have money left to upgrade to CT27 and maybe some other things. If we look at it that way, gen2 would be a better buy for the money. But that's just my opinion.

That is a bad arguement just because the CT27 is going to be right around the same level as a CT20B and the money that you would use to get the CT27 kit plus supporting mods is pretty much what you would spend on getting a GenIII anyway.

[rhouck]

Originally Posted by Triad.:

That is a bad arguement just because the CT27 is going to be right around the same level as a CT20B and the money that you would use to get the CT27 kit plus supporting mods is pretty much what you would spend on getting a GenIII anyway.

and I see people selling their ct20bs straight off the clips they get for the same price as a ct27... soooo if they wanted to they could just do that...

the fact that you can tune a Gen3 with just boltons and an SAFC to 300+ rwhp (no larger injectors, no turbo upgrades, etc) is pretty impressive imo...

100% STOCK a gen3 w/ 245 crank hp can run ~13.7 through the 1/4 mile.... that's a pretty damn big jump over the gen2's numbers

[Paul Boz]

If you upgrade the genII motor to a wolfkatz rail and bigger injectors, and get a ct20b, is the difference even that big any more? I know there are other upgrades from the genII to the genIII, but those are the biggest of them. I can't imagine everything else adding up to that much of a difference.

[Triad.:]

Originally Posted by Paul Boz

If you upgrade the genII motor to a wolfkatz rail and bigger injectors, and get a ct20b, is the difference even that big any more? I know there are other upgrades from the genII to the genIII, but those are the biggest of them. I can't imagine everything else adding up to that much of a difference.

not much. But the flow characteristics of the intake mani and increase TB size are fairly apparent. Lack of AFM always helps too....

[Paul Boz]

Originally Posted by Triad.:

not much. But the flow characteristics of the intake mani and increase TB size are fairly apparent. Lack of AFM always helps too....

The genIII throttlebody itself is bigger? I thought the difference in size was the TB inlet in 93, over the 91-92. Also, couldn't you get the 2nd gen head ported for the same, if not better results? I figure that if you have goals of upgrading cams eventually, it wouldn't be that big a deal.

[Triad.:]

Originally Posted by Paul Boz

The genIII throttlebody itself is bigger? I thought the difference in size was the TB inlet in 93, over the 91-92. Also, couldn't you get the 2nd gen head ported for the same, if not better results? I figure that if you have goals of upgrading cams eventually, it wouldn't be that big a deal.

yeah you could get it ported, but you still have the TVIS crap in there which just keeps driving up your cost to get to the same level as a GenIII in the first place.

[Paul Boz]

Originally Posted by Triad.:

yeah you could get it ported, but you still have the TVIS crap in there which just keeps driving up your cost to get to the same level as a GenIII in the first place.

How much does a genIII head typically go for? Can one even find genIII heads seperate from the shortblock?

[Nacho]

Originally Posted by rhouck

I will say the octane difference is an issue worth considering. In my experience, the motors do not really run correctly with less than 94 octane fuel.

Mine runs fine on pump 93.

[rhouck]

Originally Posted by Nacho

Mine runs fine on pump 93.

heh well "good" 93 is probably fine as well I say 94 because 98 RON is ~ 94 PON.

Unfortunately, while 93 may fit the bill, 91 and 92 octane rarely seems to

[MR2T32]

That is a bad arguement just because the CT27 is going to be right around the same level as a CT20B and the money that you would use to get the CT27 kit plus supporting mods is pretty much what you would spend on getting a GenIII anyway.

I don't think it's a bad arguement because the CT27 will be pretty much a brand new turbo compared to the CT20B that's on the Gen3 motor. So pretty much, one gets a motor with a brand new turbo while the other gets a used turbo not knowing how the previous owner took care of it.

[Nacho]

Originally Posted by rhouck

heh well "good" 93 is probably fine as well I say 94 because 98 RON is ~ 94 PON.

Unfortunately, while 93 may fit the bill, 91 and 92 octane rarely seems to

Yea, here's some others.

http://www.btinternet.com/~madmole/R...RONMONPON.html

[GReddySetGO]

Gen3 head > Gen2

I agree with 47MR2's on this. Most people who are trying to say Gen1/2 is better, or just as good etc. Have never had a Gen3. I've had both, and so have many other people. Ask anyone whos had both, and they will tell you Gen3 is the way to go.

Not the people who can say Gen1/2 is better, but have never owned a Gen3. They've only read about it, or "I've sat in a Gen3 before" type of situation. Take it from those who have had both, like me. Gen3 is the way to go.

[rhouck]

Originally Posted by GReddySetGO

Gen3 head > Gen2

I agree with 47MR2's on this. Most people who are trying to say Gen1/2 is better, or just as good etc. Have never had a Gen3. I've had both, and so have many other people. Ask anyone whos had both, and they will tell you Gen3 is the way to go.

Not the people who can say Gen1/2 is better, but have never owned a Gen3. They've only read about it, or "I've sat in a Gen3 before" type of situation. Take it from those who have had both, like me. Gen3 is the way to go.

well... that's not usualyl the best way to go about things because if they own a gen3 now that they paid MORE for, of course they're going to want to justify their purchase as being better

what you should do is listen to my opinion because I currently own a gen2 (but I am personally familiar with the gen3) and still will say the gen3 is better