dizwiz24

Is there any reason why one should avoid setting up a motor to be a high rpm solid-lifter screamer, with a supercharger?

Sure, I realize that superchargers have a max impeller speed that cannot be exceeded.

I see advantages to a high rpm screamer, because you can stay in boost longer, by being able to rev it out to a 6800+ redline. Meanwhile, your competition has to 'shift' gears.

mnstrlt1

Nthing wrong with the idea. In fact, I do believe there are a handful of c4 owners that run solid roller cams. The main issue with the solid roller for Lt-x's is the sensitivity of the knock sensors... Although I don't know first hand if this would "really" be an issue at all.

Off topic: also, you should just start adding more boost to the stock bottom end and see how long it will last. I know several members point out that 10psi is absolute max and that the rings will only last an "x" amount of time... I don't believe this is true. I ran about 9-10 psi for over a year (without meth), but the car RARELY saw that kind of boost level, because I literally drove around below 3k rpm with occasionally blasts to redline.

dizwiz24

For a lot of the guys here, its once-bitten, twice shy.

Its just like the early days of nitrous, most failures occurred because someone didnt have enough fuel, too much timing, etc.

Todays wet based systems (like NX - sprays fuel and nitrous together) are completely safe on a stock bottom end (though may need a bigger fuel pump).

However, a lot of the old-timers remember the early days of nitrous and think it'll ruin the motor.

When something went wrong on FI, there was a reason WHY. Not enough fuel, too much spark advance, environmental conditions not optimum for the tuning on their car (Ex. hot day, heat soaked motor, lugging it up a hill at WOT), bad gas, etc.

Black bart said his stock bottom end motor worked fine on FI until he got bad gas and detonated. But he gave us a big clue right there.

Bad gas. This is why I avoid 'Mr. Cricket and other no-name gas stations'. Its always BP - 93 octane for me. I know its available everywhere and I doubt the BP tanker truck is going to put 87 into the 93 tank!

drjimmy

Only possible pitfall would be choosing a cam with too much overlap.

qwiketz

I'd love to have a high rpm engine in my car. Higher rpm would mean that I could get the same blower speed with a larger diameter blower pulley. That would reduce potential belt slip which I've fought for the last 6 years.

However, with todays cam profiles and valvetrain technology, you can get a hydraulic roller that really spins up there. Look at NMRA's renegade guys who spin their hydraulic cams up to 9000 rpm! I'd love to get 7000 rpm out of my engine someday!

Brand-X

I have 396 LTx based engine that pulls hard to the rev limiter (6800 rpm), which puts my blower MIS at 105%. Qwiketz is right, you should probably try to fix the belt slip issues inherent in the LTx configuration before tackling how high you'd like to spin it.

My two cents, stay away from a cog setup unless you're building a purpose built track car. I havent met anyone with a street driven C4 cog setup that was happy with it. Theres a CF supporting vendor, who has a cult-like following on this board, that sells 8-rib setups that seem to work well. There are several non-CF vendors that sell fixes for the belt slip issue of varying quality and costs, also. Good luck on your build!

PS-I was on CorvetteKillStories last year and thought I saw a post by Blackbart. I havent heard his name on this board in a long time.

mnstrlt1

Well, I can literally count the number of supercharged c4's on this forum on one hand, let alone think of ANY that run anything other than the stock supercharger pulley combo or the "said vendor with a cult-status" system.

Excluding you (which I believe you run a 10-rib) and one other c4 that is running a chain on a big-block centrifugal combo.

I truly would like to hear from more supercharged c4 owners and details about their combos.

I've come to learn that belt-wrap and tension are also crucial. I've seen successful 6-rib systems that just have a good amount of belt wrap.

AKS Racing

On some combo's the 6 rib can be made to pull 30+ psi. It is all in the belt wrap, routing, and the tensioner set-up. I ran the cog set-up, and also ran the dedicated belt set-up. The six-rib serpentine has the highest reliability.

The cog is believed to have led to the demise of the trans in one of my earlier blowers.

BrianCunningham

Here's a page comparing different LTX cams

blower & Nitrous included.

http://www.streetlethal.net/camdata/

BlowerWorks

Hi DW ! Build your dream NA engine to your specs. Solid lifters, mechanical cam that turns 7200 RPM. Been there and done that and soooooo love ! If it runs good/great as a NA engine it will run just fine with a belt driven centrifugal blower. I always tell my customers that a belt driven centrifugal is no different than a NA engine running at sea level. Think about it. Take a NA engine from sea level to the top of a mountain - what happens ?

Turbos and positive displacement blowers a bit different.

I will tell you that there is nothing more fun than a SBC revving to 7200. Add the blower and we can just dream ?

I will also tell you that every 500 RPM quadriples the ROD forces !!!!!!!!! So the problem with RPM is all about $$$$$$$$$$ - LOL !!!!!!!!!

That's why a good belt driven centrifugal on an L98 (1985-91) is a dollar wise ijnvestment in RWHP !

My 2 cents - greg

AKS Racing

I agree with Greg on the above.

But when my car hits 6700 you just feel it inside. It just feels expensive. At high boost (26-30+), I try to keep it down to about 6400, but have been known to let it eat.

Superlite, Oliver billets, Oliver mains and JE customs offer some insurance, but it still feels expensive.

BTW SR 248/254 @ 0.050 with 0.720" lift with Jesel shafts on the AFRs.

qwiketz

A couple thoughts...

I heard that the CPUs on our ltx's start to have problems with fueling at 6900 rpm. There are guys on ls1 tech in the ltx forum that have hydraulic rollers rev ing to 7000. I'm not sure if you'd be able to get a boosted hydraulic setup to go that high but the point is you may not need a solid roller to rev fairly high with the new cam lobes available. A lot has changed in the past few years as far as the tech.

Brand x what are the cam specs? Sounds like a nice piece. I'd love 6800 rpm. Heck I'd love 5800 rpm out of my car(circa 1998 cam... Power falls off way early)

Brand-X

I run a custom CompCams...basically, its a high lift version of the 224-236 114 lsa shelf cam they sell (smog state friendly cam). Lift is int .614" and exh. .624"...can provide the lobes from my cam card if you want them. If you want to hear the cam, here's the link:

http://www.youtube.com/watch?v=4G13OsEY4lo

PS= I run a "12"-rib dedicated blower drive...think someone stated it was a 10-rib elsewhere..