dhpro / Slowhawk - Any chance one of you guys could post up a dyno graph or two of the current setup?

Have you checked to see if the belt is slipping on the blower pulley? Did you install larger idler pulleys to increase belt wrap? A 2.8" pulley is pretty small and the resistance from the compressor at 12psi will be high. Many plain Radix owners have fought belt slippage when running that 2.8 pulley with only 8-10 pounds of boost. This setup has more boost and increased rpms from the overdrive crank pulley.

I'd like to see how it reacts to a 3.0 (or 3.1) compressor pulley and higher timing.

 

I agree with you on this one. I personally don't think its the camshaft grind. I ran a very similar cam (218 218 .563 114) with good results on my 6L radix setup. Even if the cam is choking the top end (I dont think it is), then where is the torque? With 12psi it should be a torque monster. It sounds like its missing about 100 foot pounds or so.

 

I have the graph and I'll scan it tonite and try and post it. Didn't change the other pulleys - frankly it started to get too expensive to keep changing parts for what wud in the best case be questionable. Fact is we're a solid 75-100rwhp lo, so its likely a combination of CAM and IAT. One thing the graph shows is a very steep ramp to max power, but I haven't really had time to study it myself yet. It had a 3.0 pulley to begin with and generated 6.5lbs and 410rwhp/425torq...2.8 pulley got us another 5 ponies and then the overdrive pulley jacked up the torq. R/

 

is that with the larger balancer?

 

YUP...R/

 

two tenths on the pulley should have netted you about 1 psi, with tuning that should have been 15 or so rwhp, I am not sure what you were expecting. I would like to see the dyno graphs and possibly a screenshot of your timing tables (High/Low), and your IAT correction tables. I still stand firm in my thoughts about there being something else wrong with the set up. I do agree that this can be frustrating.....remember, it took Warren Johnson a LONG time to reach 200mph.

 

i can only run about 14-16* of timing before kr

 

I'm with you on the cam Big Tex. It might not be the perfect cam, but I don't think it's the big cause of his IAT problems, maybe power numbes, but not IAT problems. I've seen others use that same cam with a Radix. I didn't want to post again on this because I sound anti-Magnacharger when I'm really not. I like the product, and even more when it's in use for what it's best at.

I didn't bother to even take more than a second look at the dyno numbers since they aren't that important here. A Corvette or GTO's dyno numbers aren't even in the same class with having a considerable difference in drivetrain loss and engine makeup. I assume the 600rwhp versions are LS2's that are the stock form big number engines. That is a 10.8:1 compression engine that breathes well stock, let alone modded with a blower that is designed to work best at low boost. Another issue with the dyno numbers is how irrelevant they can be when working with IAT issue's. If you use a Dynojet for example, the run is about 3-5 seconds long or so. You aren't building enough heat to really hurt the power level on the dyno enough to be a problem in that amount of time. I feel that whether it's a 122HH or not, he's overspinning it for anything other than a dyno run or 0-60 run.

 

Some of what you say makes sense, however I think the comparisons are valid. Take a step back and look at the smaller MP112 and the numbers that folks are making on trucks, 500+RWHP. There was a fella here in our hood that made over 550+ RWHP on a stock LQ4 with a cam through a 4L80-E. I don't think the stock LS2 is more efficient than Randy's All Pro headed 370. The 370 alone should be in the 350-370 HP range as it sits NA, 520 HP with a blower should be easily obtainable with that set up.

Again, yes the IAT's are high....higher than I would like to see.....but I think there is more to this equation that just the IAT's. Sitting here debating back and forth about what it could be, and asking for compressor maps is not going to solve this mans issues. In fact the internet is not the place to "trouble shoot" a problem of this caliber.

 

Well put on all points Brian. I agree that his power level is well under expected for sure. This would be an interesting challenge if it were in front of me. It's very hard to figure out from here.