FM13 or Comp XR275HR-12

**Roastem** · 01-05-2006, 06:32 AM

I just bought the Comp XR275HR-12 for 350 bucks. The dyno shop told be I should go with the FM13. The car is going to be a daily driver, and I have ordered the 918 springs, the hardened pushrods are already in there, and I have ordered an LS6 intake. The car has full exhaust already, and I ordered a port and polished throttle body from Shaner. Should I sell my new Comp, and buy the FM13? I will lose money on selling the Comp, plus the FM13 is more expensive. What should I do, go with the dyno guys recommendation?

**Zboner** · 01-05-2006, 06:50 AM

i would go with what they recommend

**MadSeason** · 01-05-2006, 09:07 AM

Originally Posted by Roastem

I just bought the Comp XR275HR-12 for 350 bucks. The dyno shop told be I should go with the FM13. The car is going to be a daily driver, and I have ordered the 918 springs, the hardened pushrods are already in there, and I have ordered an LS6 intake. The car has full exhaust already, and I ordered a port and polished throttle body from Shaner. Should I sell my new Comp, and buy the FM13? I will lose money on selling the Comp, plus the FM13 is more expensive. What should I do, go with the dyno guys recommendation?

He probably has tuned an FM13 before and has a file to work from thus saving him time and making money off you in the tune. Nothing is wrong with one cam over the other, just depends what you're looking for personally.

**hammertime** · 01-05-2006, 01:21 PM

That cam on paper appears to be larger than the one you selected. What criteria did you select it for? Are you shooting for a specific HP number, operating range? Are you trying to cam a car and keep its street manors?

If he insists on your getting the F13 or he's gonna charge you more, then you may want to consider another tuner.

**ninobrn99** · 01-08-2006, 02:26 AM

what are the specs of your current cam? The shop really shouldnt be recommending a cam unless its theirs. They're probably just trying to give you a tune from something else. If your content with your current cam, then stick with it. I have the f13 and have to say it is a nice cam! I think they're just trying to make a quick buck on you

**Roastem** · 01-12-2006, 11:32 AM

I am gonna stick with it. Thanks guys!

**TransAm45** · 01-31-2006, 04:48 PM

What kind of numbers would be seen with that XR275HR?? I read in a super chevy article that they saw 450hp and 422 ft/lbs at the flyweel on a crate ls1.. and the 450hp carried from 5800 to 6100. This would be around 400 rwhp with an M6 wouldn't it. Or is this crate different than our LS1's??

-By the way.. I am referring to a 2002 Firehawk LS1... what kind of numbers would this cam produce??

-Edit: I just realized that this motor was run minus the accessories.. and plus an electric water pump-

**Roastem** · 02-01-2006, 07:19 AM

I don't know if I can make 400 rwhp with that cam. Probably, with the LS6 intake and Shaner TB, full exhaust, I can make close to that. I don't want an extreme cam, as the car is my daily driver. In that article you spoke of, they used a bigger cam in that comparo than the 275, and it lost power down low but started to make it when the revs went past 5800. In my opinion, that 275 should be a good cam for a daily driven vehicle.

**TransAm45** · 06-03-2006, 07:13 PM

The reason that ls1 had so much hp was because they ran it without accessories and an electric water pump....

**Roastem** · 06-07-2006, 07:14 AM

Look in sig to see real world power numbers for that Comp 275 cam.

**DocEwww** · 06-09-2006, 02:57 PM

Originally Posted by Roastem

Look in sig to see real world power numbers for that Comp 275 cam.

Pretty weak for having supporting mods, no offense. I'd guess thats either a baby cam or the tune blows.

**Roastem** · 06-12-2006, 05:19 AM

Yep, but most say it should be in that range. It is a 222/224 cam, with like 0.567 something lift. That is a mid-range cam. The torque curve is high and flat though, and so is the HP curve. What you are looking for is area under the curve, not peak numbers. I saw big cams putting out 400 something at the wheels but the bottom end torque suffered.

With bolt-ons this car only spat out 326 rwhp. I got 46 whp out of the cam/intake swap, I don't think that is too bad.