I have researched every mustang forum I can find for the past 4 months and I still have way too much conflicting info. I really want to swap cams in my pi headed npi GT, its still just too slow for me. I really want the xe262ah's but comp cams has swore to me that I will run into PTV issues, its a FACT. Is this true? Is there anyone else with these on an Pi headed npi bottom end? Second choice in cams was what comp recommended to me which is the 268H npi cam. The problem with that cam is that information is not really out there, is there someone who can clear this up? The last 2 cams are VT/CMS stage 1 and MHS stage 2 (since its a mild stage 2) again, lol Is there anyone out there with em on a pi headed NPI car? I have everything I can think of besides cams and a built bottom end done to my car, its no doubt a solid 13 second ride, but im looking for a decent driver with 12 second potential. Most of all im just looking for experience on the matter, Nick @ MHS may win me yet.
Please help me out with cams
- Thread starter tekcisGT
- Start date
duff daddy
Legend
You can get nicks cams. i had comp 270 for the pAst 2 years and not one issue
DropTopPony
Post Whore
Your problem isn't with the NPI shortblock as all the 2V pistons that aren't notched have the same PTV clearance as the contact would happen on the outter edge of the piston not in the dish.
From what Nick at MHS has said the PI valve has a thicker margin on the valve compared to that of the NPI and aftermarket valves and gives less clearance and thats why some get PTV when not degreeing them in.
Many guys have run the VT/CMS stage 1's with no issue at all and thats a set of cams that will get you a solid 25rwhp. The problem people have with the Comps is they were grinding a 4-5* advance in their off the shelf cams and guys were not degreeing them and thats where the stigma came from. I have used the Comp 262 and 270 on my car but they were used with ported heads and aftermarket valves.
From what Nick at MHS has said the PI valve has a thicker margin on the valve compared to that of the NPI and aftermarket valves and gives less clearance and thats why some get PTV when not degreeing them in.
Many guys have run the VT/CMS stage 1's with no issue at all and thats a set of cams that will get you a solid 25rwhp. The problem people have with the Comps is they were grinding a 4-5* advance in their off the shelf cams and guys were not degreeing them and thats where the stigma came from. I have used the Comp 262 and 270 on my car but they were used with ported heads and aftermarket valves.
Yeah, im thinkin Nicks gonna get my business anyway, dude has serious customer service skills to say the least. Last time I talked to him I told him I was going to wait and just get ported heads and cams together...but its like trying NOT to scratch your balls, so.... Right now im ordering a cam degree wheel and some other swap needs. As far as your xe270's, did they drive okay? I think they are on the big side for a stock head.
DropTopPony said:
DropTopPony
Post Whore
My comps were good, both sets. The 262ah were about on par with a VT/CMS stage 1 which is also good for street only cars.
There may be several types of 2V pistons for 4.6's but that doesn't make much difference when it comes to PTV. Comp is covering its ass when it says the pistons matter because they don't.
If you take a look at a 2V piston that has been cut for valve relief you notice the cuts are on the outside of the piston because this is where the valves will make contact. So you can run a flat top, 10cc dish,17cc,23cc dish etc the same set of cams would make contact on all of them if not installed properly because the dish is in the middle of the piston and thats not where the valves hit on our setups.
Go with Nick, he is a great guy to deal with and won't BS with you. I have been happy with the service i've received from him.
Look at where the Valve Relief cuts are on this MMR 2V piston.
There may be several types of 2V pistons for 4.6's but that doesn't make much difference when it comes to PTV. Comp is covering its ass when it says the pistons matter because they don't.
If you take a look at a 2V piston that has been cut for valve relief you notice the cuts are on the outside of the piston because this is where the valves will make contact. So you can run a flat top, 10cc dish,17cc,23cc dish etc the same set of cams would make contact on all of them if not installed properly because the dish is in the middle of the piston and thats not where the valves hit on our setups.
Go with Nick, he is a great guy to deal with and won't BS with you. I have been happy with the service i've received from him.
Look at where the Valve Relief cuts are on this MMR 2V piston.
Thanks for the recap! I am well aware of what the 2v pistons look like, where the contact occurs, and how to fly cut them. This is the deal, most people think that ptv is all about cam size and piston design but there are many more factors than that (im sure you know). Now, if the NPI and PI heads are two different heads, then the combustion chambers are as well. Meaning that the smaller PI combustion chamber could possibly have the valves sitting lower than the valves on the npi head. This is why I think there is confusion, even tho the piston has gotten the blame of it all. Now if you say the 262ah and 280h are good to go, I believe you (and various other sources). My main goal was to get the opinions of people who have used these cams. The MHS stage 2 cam is actually smaller than the comp stage 1 262ah, but its got a better ICL and LSA for an ALL MOTOR car. This is where alot of power is made in a smaller range (narrower band) than say one with a 112-114. Even tho the MHS cam would probably still outrun it, I would like to see a couple dyno charts. thanks.
DropTopPony
Post Whore
Next time I have a set of NPI and PI heads together I will check out the combustion chambers and see if the PI actually does place the valve closer to the piston. I never really thought to check before. The only difference I have ever seen/heard of difference was the different valve used in the PI heads. Ford made the margin thicker probably because they made them with improved cuts/angles to flow better then the valves in the NPI head.
I believe Nick has pictures of the different valves on his website before showing the margin sizes. You can also have the stock PI valve margin ground down for clearance like the guys from HiTech suggest when using their cams.
I believe Nick has pictures of the different valves on his website before showing the margin sizes. You can also have the stock PI valve margin ground down for clearance like the guys from HiTech suggest when using their cams.
duff daddy
Legend
I dont understand why you would go with the 62's not 70's, they drove fine on the street performed awesome, and the crowd loved the sound of em haha an the car only idled at 1,000, no 800 like some other "gangsters" around me.
Im currently going with a set of nicks stage 4 npi cams but he is a godo guy and knows his stuff for sure.
Im currently going with a set of nicks stage 4 npi cams but he is a godo guy and knows his stuff for sure.
Yes Droptop, PLEASE! I think it will no doubt be interesting either way.
Duffdaddy, every cam test ive seen including cam masters (unbiased comp vs comp shootout) shows the 270 to be only 5hp more up top and marginal loses in the lower on tq. It is my belief that the 270 needs ported heads to shine, as the tests showed. Stage 1 cams get almost every bit as a stage 2 in most cases with stock heads and no loss in torque down low. This has been the case everywhere I have looked unless were talking hitech stage 2, which is probably the best proven cam out there. Too bad it wont fit w/o taking the heads off and notching or valve grindin...this is Hitechs advice.
Duffdaddy, every cam test ive seen including cam masters (unbiased comp vs comp shootout) shows the 270 to be only 5hp more up top and marginal loses in the lower on tq. It is my belief that the 270 needs ported heads to shine, as the tests showed. Stage 1 cams get almost every bit as a stage 2 in most cases with stock heads and no loss in torque down low. This has been the case everywhere I have looked unless were talking hitech stage 2, which is probably the best proven cam out there. Too bad it wont fit w/o taking the heads off and notching or valve grindin...this is Hitechs advice.
duff daddy
Legend
tekcisGT said:
Yea I didnt think about driving the car at a lower rpm shifting at 6k doesnt really leave much to the "low end" haha and I have ported heads, I forgot you wernt going that route.
Good luck with the 62's
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