T-Rex in a 402?
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On The Tree
Joined: Jan 2005
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From: Boulder, CO
T-Rex in a 402? I tried searching, and didn't come up with much. FFHP recommended the T-Rex to me for my 402 long block with Patriot Stage 3 heads that they're building.
I've got a LS6 intake manifold, and do not intend to upgrade it. I have Stainless Works 1 3/4" headers, stock cats, and stock exhaust. Stock exhaust flows a *bit* better on a C5 than an F-Body, but will still be a bottle neck, I assume. It's going to stay N/A, and be a daily driver taken to road-courses rarely, and the drag strip very rarely, if at all.
I formerly had a 224/224 0.581/0.581 114LSA cam in my stock-headed 346, and it idled really nice and had good low-end torque (IMO). T-Rex is 242/248 .608/.612 110. My questions:
1) Is the ramp rate and lift of the T-Rex okay for Patriot springs?
2) How will a T-Rex in a 402 be for idle and driveability compared to a 224 cam in a 346? 242/248 seems awfully big...
3) A 6 degree split seems pretty common for a 402. Is a 6 degree split optimal for my car, with my planned heads, LS6 intake, and stock exhaust?
Thanks,
Miles
I've got a LS6 intake manifold, and do not intend to upgrade it. I have Stainless Works 1 3/4" headers, stock cats, and stock exhaust. Stock exhaust flows a *bit* better on a C5 than an F-Body, but will still be a bottle neck, I assume. It's going to stay N/A, and be a daily driver taken to road-courses rarely, and the drag strip very rarely, if at all.
I formerly had a 224/224 0.581/0.581 114LSA cam in my stock-headed 346, and it idled really nice and had good low-end torque (IMO). T-Rex is 242/248 .608/.612 110. My questions:
1) Is the ramp rate and lift of the T-Rex okay for Patriot springs?
2) How will a T-Rex in a 402 be for idle and driveability compared to a 224 cam in a 346? 242/248 seems awfully big...
3) A 6 degree split seems pretty common for a 402. Is a 6 degree split optimal for my car, with my planned heads, LS6 intake, and stock exhaust?
Thanks,
Miles
Originally Posted by Miles in Florida
1) Is the ramp rate and lift of the T-Rex okay for Patriot springs?
2) How will a T-Rex in a 402 be for idle and driveability compared to a 224 cam in a 346? 242/248 seems awfully big...
3) A 6 degree split seems pretty common for a 402. Is a 6 degree split optimal for my car, with my planned heads, LS6 intake, and stock exhaust?
2) How will a T-Rex in a 402 be for idle and driveability compared to a 224 cam in a 346? 242/248 seems awfully big...
3) A 6 degree split seems pretty common for a 402. Is a 6 degree split optimal for my car, with my planned heads, LS6 intake, and stock exhaust?
I have also heard that the t-rex is a nice cam for larger CI motors. It will probably be very similar to the 224 in yoru car now. You could easily go much bigger in a 402.
Originally Posted by GuitsBoy
I think youll be fine with any of the gold dual kits out there
I have also heard that the t-rex is a nice cam for larger CI motors. It will probably be very similar to the 224 in yoru car now. You could easily go much bigger in a 402.
I have also heard that the t-rex is a nice cam for larger CI motors. It will probably be very similar to the 224 in yoru car now. You could easily go much bigger in a 402.
According to my dialed in VE table peak torque with AFR225s is about 5600rpm.
It's pretty doggy down low (below 2k) and it is tuned out perfectly (wideband all within 0.5% down low)
It is an animal up top. It comes on real strong about 3k and according to my logs I am pulling 68-72lb/min of air up top. With that I am going larger on the cam. Im having a 247/252 .646/.638 ground up as we speak. Hopefully that will bring the 225s to their peak potential with this combo.
If you order it on a 112 or 114 LSA, you'll be much happier with it in a 402. The 110 LSA split is to keep the peak power below 7k on a 346 and to give a more violent, narrow powerband. The 402 will swallow it and make the powerband even more narrow, while bringing the peak down too low.
With a 114, it'll make peak power around 6300 RPM, will idle better, and will give a broader powerband. But honestly, you'll need an 11.5:1+ CR for it to work well or even better an 11.8:1 to 12.1:1 CR to be ideal (59cc heads and 7cc dished pistons on a 0" deck height with a .040" thick gasket gives 12.1:1 with a 402/403). Don't be afraid of compression when you have a cam that lowers your dynamic compression. Doing this will also help the torque figures.
And, the Patriot springs should do well with the T-Rex, because you won't need to spin it really high to make nice power. The only concern I'd have is with valvetrain harmonics at high RPM, but as I said, the lower peak will negate this.
With a 114, it'll make peak power around 6300 RPM, will idle better, and will give a broader powerband. But honestly, you'll need an 11.5:1+ CR for it to work well or even better an 11.8:1 to 12.1:1 CR to be ideal (59cc heads and 7cc dished pistons on a 0" deck height with a .040" thick gasket gives 12.1:1 with a 402/403). Don't be afraid of compression when you have a cam that lowers your dynamic compression. Doing this will also help the torque figures.
And, the Patriot springs should do well with the T-Rex, because you won't need to spin it really high to make nice power. The only concern I'd have is with valvetrain harmonics at high RPM, but as I said, the lower peak will negate this.
