| Go back to previous topic | | Forum name | Turbo/Nitrous Tech | | Topic subject | Turbo grind cams | | Topic URL | https://forums.2gnt.com/dcboard.php?az=show_topic&forum=i8&topic_id=35726 |
35726, Turbo grind cams Posted by Z87RSMan, Dec-09-02 03:17 PM
What are good lift and duration for a turbo grind cam? It would be VERY helpful if someone had specs for a pushrod motor using a turbo grind cam as well. Thanks
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35727, RE: Turbo grind cams Posted by 420aturbo, Dec-09-02 11:37 PM
I have a set of 0014 cams from Crane for my Eclipse. Here are the specs:
int. lift .364" int. duration 246 (advertised) exh. lift .344" exh. duration 238 (advertised)
As for spces on a pushrod motor such as you Mustang motor, I'm not to sure. I believe that most turboed motors like big lift/short duration cams with not a lot of overlap.
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35728, RE: Turbo grind cams Posted by MetalJim, Dec-10-02 06:46 AM
The overlap duration is going to be the key. You don't want lopey cams. High overlap causes reversion because, on a turbo head, the pressure is higher on the exhaust side than it is on the intake side. I think a street grind advertised with "good idle"(25-15 degree overlap) should work well if you want something off the shelf. I guess most of the big dogs don't offer a "turbo grind" for the HO, but if you can afford a custom grind then someone should be able to do it. If you do go with a custom grind - they may be able to help you out with designing the profile.
If you do need a custom grind stick with an overlap that offers "good idle". The real trick to a turbo grind is to use a smaller exhaust lift. Smaller lift will allow the exhaust gas to expell at a higher pressure. This makes the turbo spool better. One other great benifit that I can see with the smaller exhaust lift is that it reduces the exhaust duration requirements, which helps to reduce overlap, which in turn helps to reduce reversion. Take a look at the availiable turbo grinds for the 420a. Its not a pushrod, but essentially the overall profile design should be similar to what you would need to make a good turbo grind for any motor - the intake side is a mild drag grind and the exhaust side is a street grind. If you need alot of flow(big turbo) then raise the lift but try to keep the overlap as low as possible - you can keep duration down by making the main event angles as steep as possible.
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