supercharging

[sothpaw]

Am I right in accessing that supercharging an LT1 would take some reliability out of the car?

I have read in my brief searches that you need an MSD box with the charger, to retrard timing. The boxes are known to leave you on the road side sometimes. Also, I'm not sure if the drive train would hold up to 420 hp (flywheel). I think the ZR1 has some common parts, but I don't know the whole drive train (minus engine) is common. And then there's the quality of the charger itself...

Any body out there with an supercharged LT1 who wants to comment?

 

[Vettelt193]

not personally, but i have personal experience with multiple supercharged LT1's. Basically, from the engine standpoint, the more power you get out of it, the less reliable it will be... but, LT1's supercharge well, as long as they are properly tuned. ATI and Vortech make kits... it is the whole package, everything you will need.... both kits are excellent, ATI is best (it is intercooled and self lubricating) LT1's are very reliable to 425 HP or so.... above that and you need bottom end work done... Basically, supercharge OR do Heads/cam etc.... don't do both without beefing up the bottom end.... The driveline is basically the same between the ZR1 and LT1/6speed cars... reliable up to 425HP as well, but you will wear things out quicker with more power... it all still comes down to how you drive your car.

 

[Mad-Mic]

theory is stock hp divided by 2 = how much your motor will hold with out too much stress in breaking parts in your drivetrain. so 300 hp divided by 2 = 150 + 300 = 450 hp this is what i was told about a stock motor and drivetrain. superchargers only work at WOT so if your putting around town just toying your drivability on parts should last a long time. when you add more hp though parts will wear out faster. the ones like crank bearings, rod bearings, and wrist pins. you can always adjust the boost to lower levels when not racing with a boost retard from what i was told. oh yeah you might be replacing clutches alittle more than expected due to hard launches

 

[rrubel]

MM, why do you say superchargers only work at full throttle? By my experience and understanding, that's the exact *opposite* of how they function. A supercharger is driven by a belt attached (usually) to the crank or even driveshaft so that it is being spun at all times. This constantly forces more air into the engine. However, at higher RPMs the SC loses efficiency (and darned if I can remember why). A turbocharger (or turbo-supercharger, as its real name is) uses the heat generated by the exhaust to turn a rotor and provide more air. The faster the engine is turning under load, the more air is forced into the engine. So SCs work best at low RPMs and TCs work at high RPMs. Some cars (Toyota MR2, 1st gen) have both because the SC helps with the launch and when it's running out of breath the TC is just getting into its stride (due to spin-up lag). Other cars (Legacy B4 RSK, Mazda RX-7, last gen Toyota Supra) have two turbochargers, one small to spin up quickly and avoid lag, and one large to push tons more air after the smaller one has reached its capacity.

Sorry, that was longer than I intended.

[RICHR]

 

[sothpaw]

retarding the time

Vettelt193,

Was I right about needing the MSD box to retard timing? Is it a must? I thought so...

Did you know of anyone with the Vortech or ATI procharger that had quality / reliability issues?

Thanks as always, how is that CE? and what about the diamond? did you get it?

Mike & Rich,

I thought supercharging worked for all rpm also, as extra air always helps at any rpm.

 

[Mad-Mic]

your both right sothpaw and rich,

but full effects don't come on till RPM's spin up hence WOT. putting around at 1/4 throttle is very little wear and tear. your not recieving the full 450 hp and 500 lbs of torque at 1/4 throttle. just like turbo's most SC's don't come on till after 3000 rpm it's not lag it just needed to build boost since SC's don't have what turbo's call turbo lag. it would feel alittle more stout at normal driving conditions just tapping the gas but full effect will be noticed at WOT when that pulley starts to wind up. also it takes horsepower to make horsepower with SC's unlike turbo's using exhaust gases. i'm not sure how much it will take but guestimation is 1/2 hp for every 1 hp you make. so if your turning it at 8 psi making 150 extra ponies it takes crank 75 hp to spin it up for the additional 75+ you'll receive. i know this from our top alcohol dragster. on a 14:71 psi blower overdriven 50% takes 300 horsepower just to make any power gain that is noticable. i'm not real sure what the calculations is for a centrifical sc like ATI or the other ones listed. just ask the manufacturer how much horsepower does it take to spin it? it's like for the rest of your pulleys if it takes 7 hp to turn an alternator i'm sure it's ALOT more for the centrifical supercharger. hope this helps........

 

[Mad-Mic]

oh yeah the price difference from Turbo's to SC's is reflected in this HP loss to gain HP. hence a twin turbo system from ling 8k ATI full trim 4k turbo's will net more HP with less HP loss cause of exhaust pressure turning the turbine.

 

[Vettelt193]

the ring is on its way, i am going to get it next weekend, but still have to have it re-set with a better (more expensive) setting...

-on to the fun stuff

MSD is not necessary.... keep in mind, as much as the opti spark is a PITA, it controls timing for us. MSD is necessary for heavy boost in cars without computer controlled timing (or a more mechanical timing setup like the L98)... with an ATI intercooled, 8 psi, you shouldn't need it...

My CE is great, i am in the middle of some minor fixes, but so far I love it!

Supercharging does work at all RPM, but if you are just cruising, your car won't take advantage of the boost, so you will get the same gas mileage if you don't have a heavy foot... however, if you are just cruising and get on it, the boost will be right there