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Discussion Starter · #1 ·
Please help me decide.

I'm trying to buy this van and I have heard people tell me that the non-super charged versus is dead slow and a pig?

And as luck would have it I have found a van I think is really good at a good price and it's a non-super charged version! What to do?

Any opinions out there from you non S/C drivers?

Later, Digs
 

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1995 Previa SC
1995 Previa
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I have owned a 1991 non-SC and now own a 1995 SC. The SC has better pick-up, however it is noticably louder (when the SC kicks in) and the gas milage is 3 to 5 mpg less. I would go back to my non-SC without hesitation. The best way to judge is to drive one of each (if possible).
 

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It's pretty funny that the non-S/C Previas have this reputation. The reputation always seems to be passed on by people who have never driven nor owned one. Mine has more than adequate power, even with a full load of people or cargo.
It could be that the Non-S/C AWD Previas might seem underppowered, but like ciw noted, you need to drive one first.

C
 

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Discussion Starter · #4 ·
Hi All,

Thanks for the response. I am happy to report I am the proud new owner of a 1995 s/c AWD 'bean' with ABS and I like it a lot.

After driving two AWD versions one s/c and one without I can honestly say that the non s/c AWD is quite underpowered IMHO. I am moving from an SUV with 160hp/200ftlb and I haul a lot of gear and also tow trailers so the s/c version is exactly comparable and will do the job better. I also live in SF with lots of hills!

Thank, Digs
 

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digbyn said:
Hi All,

Thanks for the response. I am happy to report I am the proud new owner of a 1995 s/c AWD 'bean' with ABS and I like it a lot.

After driving two AWD versions one s/c and one without I can honestly say that the non s/c AWD is quite underpowered IMHO. I am moving from an SUV with 160hp/200ftlb and I haul a lot of gear and also tow trailers so the s/c version is exactly comparable and will do the job better. I also live in SF with lots of hills!

Thank, Digs
Congrats! Yeah I've had my 1994 Non SC Previa for 8yrs now and although I find it underpowered, I dont have any issues with keeping up with trafic at all. It's just that when u want to pass / overtake someone on the highway , I find it challenging.

I have to admit that these vans are super duper reliable. 300,000kms and only repairs were alternator, ball joint, bushings, tie rods and rusted AC line. Everything still works and still has original exhaust, rad, tranny etc etc. And to top it off, I use it for my business for hauling loads.
 

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Driven both 95 LE / NA and 97 LE / SC
I honestly could hardly tell the 30HP difference, but the SC has a louder wine noise and is a bit torquier.
 

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Of course there are pros and cons for each.

It also depends on the intended use and preference. In my case, considering that I am using Previa as a travel vehicle averaging 1,000 lbs payload at 80% of the time, in crowded NorthEast highways, after testing both, I opted for the SC.

If I was living in rural areas, with little payload, I might have opted for NA. It also will depend what you find. I did not want Alltrac, but found my 97 deal and it had Alltrac. So it is a little of a balancing act.
 

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FMVSS 108 FTW
1995 Previa All-Trac
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770 Posts
I love my S/C's torque that seems to start right off idle. It's still not that awesome for passing, but it does fairly well in that regard.

I've never driven the non-S/C version, though.

I suppose I could disconnect the S/C relay and see what that's like (but the static compression ratio is much lower on the 2TZ-FZE so it may not be the most accurate comparison).
 

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FMVSS 108 FTW
1995 Previa All-Trac
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I have read somewhere here that de-activating the SC makes the vehicle run poorly.
I'll keep an eye on my scanguage for any unusual data (like problems with ignition timing, for example). It's a very easily reversible 'mod'. Basically, I'd do it out of curiosity-- and I'm aware of the difference in static compression between the two motors which surely would account for some odd issues.
 

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Seeing those data would be very interesting. I don't think anything would break with a test run either, but I never tried it.
 

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FMVSS 108 FTW
1995 Previa All-Trac
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Disconnected wiring to supercharger relay yesterday. It's a slug now, for sure! I think under certain conditions I might improve mileage, but considering the low static compression of the engine, I could be wrong.
 

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I remember test driving Previas years back. The non s/c RWD ones weren't bad...but you could really tell the extra drag of the AWD driving a non s/c model.

My Dad tows a 3500 pound boat trailer with a non s/c RWD...it's slow compared to a new van with a V6, but it's certainly capable.

I've found some of the slowness feeling comes because the transmission shifts so smooth...there isn't that normal jerky feeling when it shifts under hard acceleration. It does have the transmission from a Lexus LS400 in it after all...
 

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Disconnected wiring to supercharger relay yesterday. It's a slug now, for sure! I think under certain conditions I might improve mileage, but considering the low static compression of the engine, I could be wrong.
Of course it will be a slug if you disconnect the SC.
the compression ratio for SC and non-SC are different. the non-SC has higher compression ratio at 9.3, SC has only 8.9. that's why under boost, the SC adds 5 PSI more than the non-SC, which makes more power.

I also have an SC model, if I had to rebuild my engine, i would increase compression to match the non-SC, then keep the boost at the stock 5PSI. the SC internals can handle up to 7PSI safely. take note of the keyword "safely". that should give you enough "umph!"
 

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Driven both 95 LE / NA and 97 LE / SC
I honestly could hardly tell the 30HP difference, but the SC has a louder wine noise and is a bit torquier.
No you didn't. All 1995+ models came with S/C standard, as the only option. You couldn't have driven a '95 non-S/C, they don't exist. Just some clarification for ya.
 

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FMVSS 108 FTW
1995 Previa All-Trac
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Of course it will be a slug if you disconnect the SC.
the compression ratio for SC and non-SC are different. the non-SC has higher compression ratio at 9.3, SC has only 8.9. that's why under boost, the SC adds 5 PSI more than the non-SC, which makes more power.
Gee, why am I reminded of those LOST recap episodes with the subtitles like: "This is Benjamin Linus. Benjamin Linus was the leader of the Others."?
Anyone who watches LOST already knows that; most people who own Previas and have internet access know the difference in the static compression ratios between the 2TZ-FE and 2TZ-FZE.

I also have an SC model, if I had to rebuild my engine, i would increase compression to match the non-SC, then keep the boost at the stock 5PSI. the SC internals can handle up to 7PSI safely. take note of the keyword "safely". that should give you enough "umph!"
I've considered that myself, and briefly considered throwing in a 2TZ-FE to take advantage of its higher compression ratios, until I recalled that there are major valve timing differences between the two engines, and that the -FZE is ODB-II compliant. Other differences are that the -FZE has a more robust lubrication system, the head gasket is better, and the piston skirts are shorter and lighter, as well as resin-coated for reduced friction. In short, the -FZE is just that much better an engine.

I'm beginning to wonder if the valve timing is the largest reason for the difference in compression ratios-- the -FZE's intake valve opens at TDC, while on the -FE it opens at 10 degrees BTDC; closing occurs at 46 degrees and 40 degrees after bottom dead center, respectively. (Exhaust timing is similarly modified, and the overlap between exhaust closing and intake opening is 0 degrees, which keeps the air-fuel mixture in the combustion chamber where it belongs, rather than being pushed through by the supercharger.) I'd have to run through one of those compression ratio calculators to know for sure.

EDIT: Update on driving without S/C for just a day:

I'm already getting used to the reduced power, and am driving like a vehicle this size with as little power as it has should be driven-- a little more gently and with a little more planning when it comes to left turns and just pulling out into traffic.

I may wire in a dashboard switch to return control of the S/C to the ECU, make it sort of a "Sport/Econ" mode switch. If nothing else, I can feel better about putting only 87 octane in it to save money (I often put in 89 octane even though it can run on 87 for light duty, according to the manual, but I'm trying to save money by getting the cheaper stuff).

If I put in a switch, I'll post a new thread with a photoessay on it.
 

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I'd be curious about the switch, thats something I'd like to do.
 

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My Supercharged MR2 has a switch that I can select what type of gas I use, either 87 or 92. I've always used 87 in my Previa S/C without any issues.
 

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FMVSS 108 FTW
1995 Previa All-Trac
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My Supercharged MR2 has a switch that I can select what type of gas I use, either 87 or 92. I've always used 87 in my Previa S/C without any issues.
I suppose now they just use better knock sensors, although the switch may still enable a timing scheme less likely to produce knock.

I can use 87, and haven't had *issues* issues, but I can feel it when I have 89. 87 is fine for puttering around in town, but when it's time to go to OKC or road trip (especially with the wife and dog and stuff), I use 89. I haven't tried 91 but don't think that it's even worth experimenting with.
 
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