Not sure what route to go...
- Thread starter DQ Dave
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iamdub
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I'd have to research the fine details of all the offerings, but I'd definitely get a roots style blower such as that from Whipple, Magnuson/Radix, Edelbrock, etc. rather than a centrifugal. Running 87 should not even be a question. If you're considering putting a $6,000+ supercharger on a vehicle you don't drive a whole lot, then spending an extra $9 per fill-up shouldn't even be a concern. These things should be fed 89 or higher in stock form, anyway.
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Subanbur
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Lol no thxmagnuson or whipple are nice
87 would suck w/ boost... but, if you like detonation & knocking, give 87 a try(may get some engine damage as well)
I’m just wondering why you would need supreme 91 oct if your not playing with the compression ration.Your basically pushing in more air. I understand higher compression = higher octane to reduce knocking or pre-donation. On my civic si I never ran with anything but 91 or better ,it’s recommended fuel anyway . Now looking up at the stats of the l83 ,it has the same compression ration as the k20z3 11:1. Why are they recommending 87 for the suburban?
Boost pressure behaves the same way as an increased compression ratio since you’re starting with an increased atmospheric pressure. 91+ is required for my Whipple supercharged 6.0. Otherwise it would knock constantly and destroy the engine.
Sam Harris
Supporting Member
91 is the best I can get in Co. [emoji3525] which I use in all my vehicles (except E85 in my Yukon [emoji6]).. I mean... unless I bought race gas.. [emoji3166]
Yep me too. It’s the minimum octane Whipple recommends but that’s the best I can get pretty much anywhere in Oregon except maybe a few stations.
iamdub
Full Access Member
As the others have said, it's to stave off preignition. The more pressure in the cylinder, the hotter the air and the more easily it ignites. Diesel engines kinda run off of detonation. You can have high compression with no knock by retarding the timing. On your Si, it was tuned to run on 91. Your L83 with the same compression is tuned to run on 87. Yes, it's kind of a waste, but the engineers have to meet specific criteria. It's easy to manipulate the timing to account for varying fuel grades. You can't really manipulate the compression ratio. You can a little (the dynamic compression ratio) with variable camshaft timing (VVT), but it's nothing like the adjustability with spark timing. So, you make the static compression ratio high and have the knock sensors tell the PCM how far it can advance the timing to make the most of whatever fuel is in it. Run 87 and it'll only advance the timing so far and you'll only get X amount of power. Fill up with 93 and it'll advance the timing a little further to take advantage, yielding more power. This is all on a naturally aspirated, stock engine. With a supercharger, you need 91 at a minimum.
Subanbur
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Thx guys , I really appreciate the input. I was wondering how’s the fuel economy on a supercharger?
Is there a way to use a clutch type system like on a A/C compressor to engage and disengage the blower pulley on the fly ? Does that make any technical sense ? What about having a propane/gas hybrid + supercharger. Propane is 110 octane.
Is there a way to use a clutch type system like on a A/C compressor to engage and disengage the blower pulley on the fly ? Does that make any technical sense ? What about having a propane/gas hybrid + supercharger. Propane is 110 octane.
that was a movie prop in mad max
although i thought procharger has some option a few years back that allowed boost to be turned down to 1# & then could crank it up when real power was needed. think it was controlled in the tune, versus a dial though.
although i thought procharger has some option a few years back that allowed boost to be turned down to 1# & then could crank it up when real power was needed. think it was controlled in the tune, versus a dial though.
If you can afford it, I would go for a Magnuson supercharger. Their kits bolt right on and I've seen plenty of used vehicles that still have them on after years of use so they're reliable. Then you can have a vehicle that drives like stock but has 150 extra horsepower. I'm doing a cam in my 08 but ONLY because I want to replace the lifters before a failure. If I had a newer truck that I had no reason to go into, I wouldn't bother with a cam. The only downside to a supercharger is the cost.
