I'm very interested in either supercharging or turboing. I'm thinking the 998 might be the go with the shorter stroke. I will probably go the supercharging option. My opinion is that a supercharger has more advantages (or should i say less disadvantages) than a turbo. I've read through the thread regarding the supercharger kit and that setup sounds impressive. What would your opinions be on the choice of motor 1098 or 998??

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Take it easy, & if it's easy take it twice!!

Well a few bods here have turboed and S/C'd 998s with good results, the main prob with 998 seems to be that when off boost there's SFA torque, as the C/R is set low for turboing.
At least 2 people are about to repeat the performance, but this time using a 1098 for better initial torque.
Let's face it, with big boost you just won't need to rev the tits off it anyhow. And the extra 100cc can only help road performance.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Turbo here....

Gotta agree with Kev, although since finishing the build of this engine, I've been reading a lot of "new" information regarding High-compression / low boost setups being marginally superior in some forms of motorsport... (ie Drag Racing)

I've gone for a "stroker" 998 this time (1100) to beef up the bottom end response, as well as a few other little tricks to gain some bottom end torque without sacrificing too much top end....

My 998 would rev to 8500 easily, but wasnt the most realiable build ever, and I was always trying to keep head-gaskets up to it ... Hopefully thats been cured now (watch this space in about a week for a report of the changes....)

The 1100 should be able to move a bit more air down low, so as well as the extra stroke being able to move the car easier, I expect that usable boost will come in a little earlier too, and a fair whack harder....

Again, watch this space and I'll tell more later....
J

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SFA torque at low rpm is what concerns me. Mabe a high compression/low boost would be the way to go? But shouldn't a supercharger act a lot quicker running of the engine? Mabe a twin turbo setup?

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Take it easy, & if it's easy take it twice!!

"Mabe a twin turbo setup?"

Have you ever seen a Turbo Mini's Engine bay ?

There would be no valid reason for having Twin turbos in a mini.. too much plumbing for so little gain....

Get a well-sized turbo (I fully recommend the IHI RHB-4 turbo for around the 1000-1200cc Engines - I'm noe running an IHI RHF-5 on mine, and the response is a little worse for the same amount of boost (all about to change )

Supercharger will give you GOBS more torque low down, and lets face it, thats where you spend most of your (Street) driving time, but the Turbo is just a lot more drivable for me.... if i want more power, i just squeeze a little harder on the loud pedal.....

J

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Hey James how about those new Porsche Carrera Turbo vaiable speed turbos? it has some advanced vairable vein design that allows it to work at lower engine speeds as well as higher speeds

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Lillee - 1969 Morris Mini K

Yea, Garrett have been working on VNT Turbos for some years now... only just starting to get them working right...

They have a series of "Blades" around the Turbine Nozzle that can alter their pitch based on inlet vacuum / pressure....Great design, but just not quite reliable enough yet, but the porsche linkup might just fix that ! (Worked for Volkswagen!)



(Bad pic, but you get the idea...)

J

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Sweet

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Lillee - 1969 Morris Mini K

I just read about Volkswagens "twincharger". It's both a supercharger and a turbo. At low RPM the supercharger enhances low end torque, and at high RPM when exhaust gases are at a sufficient quantity the turbo kicks in to increase top end performance. Apparently this is what they run on the golf GT.

Sounds interesting!

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Take it easy, & if it's easy take it twice!!

Again, a lot of complexity for not a lot of gain ....

Wonder why Toyota never continued with the Twin-charged Sprinters ?
Nissan too, and I'm sure you'll find the same with VW ....

Wayy more things to go wrong, easier to re-design the engine to get around the issues....

Good luck
J

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All must be considered to make a wise decision!

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Take it easy, & if it's easy take it twice!!

its probably the extra cost of it not being worth the gain. consumers will still buy pushrod engines remember.

turbo is more work and more complex and probably more money, but will be better in the end.

so, while the subject of fruity turbos is up, hows about pressurewave superchargers? they work off both exhaust and engine, kinda dificult to understand, but quite simple if you can find a diagram. they are dirt cheep too. (mazda 626/ford telstar 2L desils used them).
Anyone used one? on anything?
ive got one in my garage in a box that i paid $50 for, fairly compact little unit. not so usefull to me now though because my static compression ratio is on the dark side of 11:1...i think..

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speed costs....how fast do you want to go...

do you mean the so called "comprex" (made by ABB) charger?
shoud be a nice charger, but as far as i know it is hard to controll and hard to optimise.
i've been told that Volkswagen, Mercedes, Opel, even Ferrari (F1, in 1979, 1,5 liter engine) tried it. beside Mazda (owns the patents now) only Opel made some (700 units) diesel engines
will have a future, i think, as Greenpeace showed 1995 with the "SMILE" car (0,4 liter, 40kW / 75Nm)

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Rover 214 atm ....

yup thats the one. ther a compact little unit, unfortunatly im not sure if you could draw through one, itd have to be a blow through setup. BUT high boost and instant response from low revs apparantly the guy i brought mine from had one on a holden 186...i think he had diff issues

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speed costs....how fast do you want to go...