how much abuse (OD) can gtp rotors take

at what blower RPM or better said what OD do the Coated GTP rotors start flaking off ??

curious here i have 15% OD and bare rotors but wonder if the gtp rotors will withstand the 15% i dont rev the car past 5400ish if ever
usually it sees less than that but i think if was to add the gtp rotors the tighter clearance with the 15% would make better low end torque maybe not so much lower temps but a bit more boost at lower rpm points

would the GTP rotors hold their own or will i end up with coating on my precious fmic im debating wether i should try them out

still have some issues as always -.-

i really want to get this to a dyno and would love to see what 15% OD does vs 15% GTP maybe even vs 20% bare :O i have the pulleys and set up to do it just to see how it goes im thinking to keep 15% until i get a top end combo from Mr Dalke but wondering if i can throw a set of GTPs on the blower at that speed

if i can find that one issue and put the interior back together that is lol

I had a gtx (gtp with the slp package) and with a 3.4 pulley I stripped evry set of gtp rotors I had in it in less than a couple thousand miles. That said the stock size pulley on an sc is that size or smaller. The only luck I have had with rotor coating staying on is the abradive coating.

davec73 said:

I had a gtx (gtp with the slp package) and with a 3.4 pulley I stripped evry set of gtp rotors I had in it in less than a couple thousand miles. That said the stock size pulley on an sc is that size or smaller. The only luck I have had with rotor coating staying on is the abradive coating.

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Yea dave all I could find was that at 10% the gtps started flaking off

Get them done by MP!!!

superdadsc said:

Get them done by MP!!!

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They are so pricey I think I rather put that money towards the heads cam combo

I can always add them in the future but I see that being long long from now however I do wonder how well they will help on a late model blower most ppl using them have mpx and upgraded blowers

any help a late model can get is that much closer to MPX, if it allows more OD with no flaking even better Theres also the fact that if you come up with an MPX case later you can just swap the rotor pack/snout assy

Adam

I would be more worried about excessive boost at 15% OD than just the coating flaking off. M90's are extremely inefficient at high boost. You would be better off using the GTP rotors @ 10% OD until you have a motor that requires more airflow.

The GTP rotors in my wife's XR7 have been in there for many years, during most of which time I ran 15% OD. Currently it no longer has OD on it (miles are still counting up!) and no flaking whatsoever. On a stock motor 5400rpm is way too high anyway. A stock motor will not make peak power past 4800, so 5200 is plenty, especially if boost is over 15psi.

awesome dave thanks

XR7 Dave said:

I would be more worried about excessive boost at 15% OD than just the coating flaking off. M90's are extremely inefficient at high boost. You would be better off using the GTP rotors @ 10% OD until you have a motor that requires more airflow.

The GTP rotors in my wife's XR7 have been in there for many years, during most of which time I ran 15% OD. Currently it no longer has OD on it (miles are still counting up!) and no flaking whatsoever. On a stock motor 5400rpm is way too high anyway. A stock motor will not make peak power past 4800, so 5200 is plenty, especially if boost is over 15psi.

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Awesome dave yes I remember before you made my tune u told to stick to 10% but I couldnt find any other pulleys at the time, the least OD combo I can put now is a 12-13% from a snout I received recently, and I can throw the gtp rotors in there I have no other pulleys to make it any less OD , yes the trans will allow for 5400-5500 shifts on its own and i could hold 1st and 2nd high to almost 6k but thats a big NO NO i dont wanna be overstressing the motor for nothing but u can feel the car fall on its face at 4500ish I was talking to alan brown about how to swap my governor back to stock and lower the shift points

But pretty much thats what i wanted to know if the coating would hold its own
At 15% OD on bare rotors just on a 1st gear pull it was making 17psi
10% made ~16 on 3rd gear
Usually on 1st it made 14ish psi on the 10% but I hated the belt slip with that pulley

so after i get heads and cam 15% and gtp rotors will be good ?


Ohh btw crank sensor bolts were not torqued fully there was about a 1-2mm movement on the sensor which I think was enough to throw things off im on the search for a tiny wrench lol

Miguel5671 said:

so after i get heads and cam 15% and gtp rotors will be good ?

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No, with heads/cam and 15% OD you'll end up like the other guys said. It's not the OD that is the problem, it's shaft rpm on the blower. 15% OD @ 5000 engine rpm is 15500 blower rpm. With heads and cam you'll be wanting to rev 6000rpm so now to keep blower rpm the same you'd have to remove ALL OD completely. With heads and cam that would mean about 11psi which won't make you happy.

You can only get away with running 15% on those rotors if engine rpm is kept to roughly 5000rpm max which is great with a stock motor but won't work once you get heads/cam.

XR7 Dave said:

No, with heads/cam and 15% OD you'll end up like the other guys said. It's not the OD that is the problem, it's shaft rpm on the blower. 15% OD @ 5000 engine rpm is 15500 blower rpm. With heads and cam you'll be wanting to rev 6000rpm so now to keep blower rpm the same you'd have to remove ALL OD completely. With heads and cam that would mean about 11psi which won't make you happy.

You can only get away with running 15% on those rotors if engine rpm is kept to roughly 5000rpm max which is great with a stock motor but won't work once you get heads/cam.

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Ohh !! Makes sense now so with heads cam im going to want to rev a bit higher because it will still make power up top but that also means the rpm of the blower will increase by the higher revving depending on the drive ratio of it , so at 15% assuming that drive ratio at 6k rpm blower speed will be 18,600 revs :O? So gtp rotors now good idea with the lower OD and ill keep the revs down or at least try to trans likes to shift high lol

With my .519 cam my car would make power till about 4500rpm then poop out. I had 16 psi and 10% od. Car was so great at that level. It shifted low but it didnt need to go any higher. Low is safe.

Miller said:

With my .519 cam my car would make power till about 4500rpm then poop out. I had 16 psi and 10% od. Car was so great at that level. It shifted low but it didnt need to go any higher. Low is safe.

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Nice Jason
Yea my car is a street car no need for hard core revving maybe at the track if it helps but still I doubt ill rev it too high im thinking ill be shifting at 5k at the track as is I can hold 1st and 2nd and I should finish in 3rd