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The mkiv Supra Owners Club

Serious Question About Superchargers


Animal

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ok, I get you now:)

What I was trying to say though was that a 328i bmw has 196bhp stock and with a supercharger it can deliver upto stock TT power. I used the 328 as an example as it is similar to a 2JZ GE in capacity and compression and stock power output. I jusst thought the link I posted could help the OP by showing a system currently available that works within a comparable application (a bmw L6)

 

Oh right, with you ;)

 

Suppose they exist because 300bhp is quite attractive to a 328 owner, and the 328 engine probably wasnt enginered to the same standard as the 2JZ so huge gains might not be possible without major block / head work. Its less so to the average supra owner as a change to forced induction on our engines has as trends go been to obtain levels higher than stock TT otherwise its all but pointless bang for buck wise.

 

Still, do-able as shown

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Supercharging is viable as a choice simply because the power delivery is completely different. No percieved lag, and boost increases linearly as the revs go up, so it'll just feel like a bigger engine. There are also a few choices on how you go about it, unlike turbos. The roots blowers are mainly for V applications but they are actually the most inefficient design. The half-turbo one (rotrex I think?) is I think the most efficient (but still less so than a turbo).

 

The power increase limit is affected by the same factors as a turbo apart from an additional "how much power does it take to turn the damn thing". A lot of superchargers are light-pressure (5 to 8psi) simply because there is no intercooling for cost and packaging reasons. If you can intercool the charge (or chargecool it with a water to air system, favourable again for packaging and pipe routing reasons) then your boost limits are similar to a turbo. Parasitic losses are higher, of course, due to having to increase the gearing of the 'charger to make the higher boost, and as the supercharger is inherently less efficient than a turbo you'll see pro rata less power for the same boost as the air charge gets heated up more.

 

So, get a rotrex charger on an NA, run the output through a small SMIC or a chargecooler, and run yourself a bar of boost. That should make it feel like a nice 400bhp 6litre NA engine. Nice. I'd love to see a project like that.

 

-Ian

 

PS the superchargers on top fuel dragster take I think something like 1500bhp to turn :) it'd stall any Supra on this forum haha - I love that factoid.

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Supercharging is viable as a choice simply because the power delivery is completely different. No percieved lag, and boost increases linearly as the revs go up, so it'll just feel like a bigger engine.

 

Well put. That's what interests me about all this. Thank you for a well written reply to a subject that normally goes down the pan within 5 posts.

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Why not the best of both worlds, a supercharged TT motor. Retain the stock turbos (for cheapness) and slap a supercharger on to raise the boost. Packaging would be a big issue, but not insurmountable.

 

BPU it, then feed the output of the turbos into the supercharger (compound turbosupercharged :D). A more efficient type like the Sprintex screw type supercharger will compress the air slowly (due to the advancing screw action) and increase the pressure more efficiently than other types.

 

I'd like to see the power output of that one :D

 

http://www.sprintex.com.au/Supercharger_Kits.asp

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You've just got no sense of adventure have you?

 

He's a crowd pleaser, mods for others rather than for himself, probably best if you put him on ignore.

 

Have you looked over previous supercharger threads? Most seem to fizzle out to nothing but I think one went as far as actually buying and test fitting parts.

 

Personally I think you'd suit a V8 more, once that's in you can supercharge it later, I'd be interested to follow a VVTi SC project though so keep going :)

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You've just got no sense of adventure have you?

 

Sorry if i sound negative mate. Your missing the point tho, i love the idea of a supercharger on a supra, but i'm saying its not for you. Just take a look at all the ball aches i've had with the modiying that is supposed to be common place. I wouldn't like to see you go down the same slope bud thats all.

 

But if you go for it then it would be a great project like i've said. And if it goes well then there will be plenty of people queing up at the NW meets to get a ride in the passenger seat :)

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Just take a look at all the ball aches i've had with the modiying that is supposed to be common place. I wouldn't like to see you go down the same slope bud thats all.

 

Fitting dodgy gearboxes isn't exactly common place though... Having cowboys work on your car doesn't help either.

Edited by Thorin (see edit history)
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Sounds a good idea, if you have the patients, the modern crop of turbine type superchargers are quite efficient, and are geared as such as to provide good positive pressure from low RPM, you can also change the gearing to suite power delivery, within reason;)

Routes or vein type compressors are good but rob more power, which is why they are mainly fitted to large displacement, or big power engines.

As for engine choice, VVTI is probably a good one, and everything is more or less in place to deal with the extra pressure, also within reason, and you could possibly get away with even using a piggyback, you would probably notice more low down power lower down by using an N/A motor due to the valve timing etc.

Sounds an interesting project:)

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It is an interesting idea indeed and why I wanted to have a proper, intelligent thread about it, rather than the usual 'buy a turbo' threads.

 

As it stands, I probably don't have the money to be able to do this justice right now, but I will.

 

Now we actually have some good information here, back to the first question - how much work would be involved in transplanting a VVTI engine into a non-VVTI N/A? Someone mentioned using a Lexus 5 speed auto box as well, that sounds good, but possibly way too much work if the existing Supra gearbox will work fine.

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Don't know if you've already seen this but a guy over on LOC had a supercharger fitted to a UK IS300:

 

http://www.lexusownersclub.co.uk/forum/index.php?showtopic=47641&hl=

 

There's info in that thread, might be worth dropping him a PM to see what happened.

 

There was another one done as well by one of the ex-TDi techs but it was never completed - shame as it was a nice car as well!

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how much work would be involved in transplanting a VVTI engine into a non-VVTI N/A?

 

If you mean the NA VVTi engine it could be costly as I don't think many of them were made, let alone found their way to these shores. It'll be ECU and wiring loom for sure, and the associated hassle of making the wiring loom match up with whatever you don't swap - don't assume all the connectors or pinouts would be the same between models.

 

-Ian

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Ian the engines won't be in that short a supply (may still be pricey though) as the uk GS300's have them from 98 (roughly) onwards. It helps to have the VVti to get shot of the distributor of the older car as all the conversions need that space to be a straight bolt on conversion but like you say this may introduce some wiring/compatibility problems.

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