cam for a turbo motor?

[Madd Maxx]

OK MAXX because you are ROCKING SOME SUPER technical answers here. And you seem to be on a roll. I haft to ask since I am working toward a turbo. I am only plannin to prob spin up to 6200 RPMs on a 5.3 What size turbo would work best for what I am thinking. Also I was planning a 220-224 Cam with 581/581 on a 115. So by your posts to improve the gas pressure I should get a 224-220 instead? Would this still be a good NA cam till I get the Turbo system. (talking a good 6 months from the next cam swap till the turbo kit) And going back to the post in general by what everyone is said shouldnt how far Drop em runs his motor into higher RPMs play a factor in what cam he needs to run?

For your cam I would stick with your first choice. Just keep the overlap on the conservative side. With the choices of turbos available today there's no need to shorten the exhaust duration. It's much easier to find a properly sized and configured turbo for your engine today than it was in days gone bye.

For the turbo choice, the best advice I can give you is don't listen to someone you don't know on a forum. There's a virtual plethora of choices available. Contact the guys who do this for a living (Garrett, Turbonetics, etc). Tell them what you have, what you want, how you drive, etc, and let them identify your options. It would be time well spent.

As for the OP's issue, as others have pointed out, we don't know enough about his needs to make an accurate determination. I was merely pointing out that the A/R of his unit is intended for higher RPM use. He was vaguely describing a problem and I was offering a suggestion based the the available data. If his turbo is sized appropriately for his engine, then that won't be a problem. Boost just won't come on as fast as, say, a positve displacement blower (which I personally think is a better setup for a street-driven truck).

[ff_jeff]

I dont know any of you.

[Justin_Inc]

I'm not sure I follow your point, since the sentence you quoted started off with "For lower RPM use . . ."

A diesel would be a good example of an engine that would use a turbine housing with an A/R of 0.6-0.7.

Ugh... you do realize that most of the bigger diesels have A/R's of like 1.10-1.4X even 1.5X right? If you put a 0.6-7 A/R ratio turbine housing on a diesel the back pressure would be so high it probably wouldn't run off idle. Sorry bud.

We dont really know enough details on the build but even on a 370" engine that cam would be about right IMO, maybe drop down to a 1.6 rocker to tame it out more. But I think the OP needs to chime in and let us know details.

If the issue is boost not coming on quick enough with a .9X turbine on a T76 on a 370+" engine then i'd be more inclined to say there is something either wrong with the hot side, a restrictive exhaust or the tune as that baby should spool up pretty damn quick.

[Madd Maxx]

Ugh... you do realize that most of the bigger diesels have A/R's of like 1.10-1.4X even 1.5X right? If you put a 0.6-7 A/R ratio turbine housing on a diesel the back pressure would be so high it probably wouldn't run off idle. Sorry bud.

Yes, that's true, but the world has more to offer than big-ass truck diesels. Go across the big pond and grab a smaller car, like a BMW 320d with a turbo. You'll find it has something similar to a Garrett T25, which on these cars uses a turbine housing with 0.64 A/R.

I suggested diesels for low a A/R because they typically don't rev over 4000 RPM. And yes, there are usually exceptions to every generality, but I guess I should have given a specific example. My bad.

[dropem]

ok sorry it took so long to post but the motor is only like a 370. the turbo itself spools up just fine its all there about 1500 rpm so thats not the issue it just seems that there is still a lot left on the table with my cam now because i have been looking at other turbo motors like mics for example he has a 230/236 .612/.607 114 lsa +2 cam and he has the exact same motor exept i still have the stock manifold and i have a 76mm and i also heard virgils is pretty big also this is just what i think the motor runs just fun and it pulls really strong but i just think there is alot i could gain by a different cam

[mean05]

mine is a 250/244 .634/.623 114lsa and i added 2 more degrees into it....my cam was speced for the motor to make some big big power...but i really dont know a whole lot about this cam and how well it is going to work...it was also supposed to have L92 heads that have been PnP to flow some badass numbers

[dropem]

well it doesnt really seem to choke any it runs fine just it seems like i could gain alot from a bigger cam because im swaping springs so i will be able to support a bigger cam and i run it to about 6300 and it doesnt choke up

[mean05]

well it doesnt really seem to choke any it runs fine just it seems like i could gain alot from a bigger cam because im swaping springs so i will be able to support a bigger cam and i run it to about 6300 and it doesnt choke up

go to DallasPerformance.com and talk to Taylor...give him all your specs and see if he can have a cam made for you

[Justin_Inc]

do you have a back pressure gauge? thats how you can tell if your running into high back pressures. seen numerous 76mm choke up around 6k

True, i'm going to take a stab and say its a T4 housing. But at that low of a boost pressure it shouldnt be too bad yet.

[dropem]

ok guys. Well thanks for your help I might just step it up a little then