So how high should you go?

 

We can only physically spin them a little higher with smaller pulley's even on the Inlet Forward MP122HH Confguration.

I wouldnt worry about how fast you are spinning it in the Radix MP122HH Configuration. The Radix MP122HH can only be spun as high as 18,909 at 6,500 Engine RPM's with a 2.75 Blower Pulley and 8" Crank Pulley.

I think the biggest determining factor in a MagnaCharger build is the Cam Profile. I have access to several different profiles that are doing great with MagnaChargers!!

 

I have decided to try two things to see what effect they will have on my new setup.

1) Change the cam from the LPE GT2-3 to a "blower-specific" grind.

2) Install an ASP Racing 8" 8-rib pulley conversion setup using the same 2.8-2.85" snout pulley diameter currently installed.

I will let everyone know what the results are as soon as each item is completed and retuned.

 

I'm all ears. What cam are you considering? The cam in my sig has made about 100 more HP at only slightly more boost with a trick turbo. Are you sure your belt is slipping? Have you tried a belt "treatment"? It makes the belt tacky. Not a long term solution, but it would tell you if your belt wasn't doing its job. Other belt treatments involve a powder type stuff that helps the belt effectively have more surface area. Kind of makes a smooth belt have more grab.

 

The cam that I'm switching to is a custom blower grind with 222/228 .566/.571 114LSA; valve events at .050:
Int = Open -2* BTDC / Close 44* ABDC
Exh = Open 49* BBDC / Close -1* ATDC

This provides 113* intake centerline and 115* exhaust centerline and -3* overlap. Definitely no bleeding off boost with this one.

As for belt slip, I'm not currently experiencing any slip with the oem crank pulley and a 2.85" SC snout pulley. However my intent has been to run 10-11 lbs boost. I was getting belt slip with my 112 running 11 lbs peak boost with a 2.8 pulley (evident by the powdered rubber on the alt bracket) so I figure the 8-rib is a safe investment in the event I get the itch to bump up the boost further.

 

How about the numbers at the seat? .050 numbers dont always mean anything.

R

 

Sorry, I have not seen a "cam card" yet that shows numbers at .006 and never received a full spec sheet for any cam I've bought...including the 226/230 that I bought from you. I've contacted Comp Cams for a full spec sheet, but doubt that they will provide one...I'll likely have to get it Cam Pro'd to get those numbers. It does have Comp XE ramp profiles...if there is any standardization to those for calculating.

Any thoughts on the compression (11.5 SCR / 9.03 DCR) you asked about? Maybe swapping to my Absolute Speed 241 castings from the AFR 225s to raise compression?

 

http://www.compcams.com/Technical/Ca...obeCatalog.pdf

That might help with the specs...

 

I was not saying that its anyones job to provide the numbers at the seat, I was only asking to figure out more about the cam. More is learned from seat timing and this is who I build all my cams, not by the .050. I know comps lobes very well and use them alot, so I pretty much know your cam now.

Also, the other things most of you should get to understand is that Every cam has overlap. To say it has no overlap is wrong. When defining overlap, you should say this one cam has a lot less overlap than my last cam. It helps everyone else to understand more.

The reason why compression is a little more important in a blower like yours is due to the fact that the more air needed to fill a chamber, the hotter it gets. Same with going to a bigger camshaft. The blower will get hotter because you are asking it to feed more now.

This is also where the three rules apply to boost. Power is made by boost, timing then compression last. In that order do you build a platform. The reason this is important is because it comes down to how much boost are you running. Then what kind of timing do you want to run, and from there you can decide on how much compression you need. The reason the timing is important because you need to match timing to the cam profile. You can put X cam in there, and be so far off on timing because it pings that you are no longer "on" the camshaft for making power. So now everything is wrong. So instead of just throwing parts at it, try sitting down and figuring out everything I guess said here.

R

 

Guess I don't have the math skills needed to determine the valve events from lift & duration? I'll research later to see if there are calculators online that can work from the info given.