Valve train and cam question...

[IceDragon]

Easy answer...

Do you need to re-do your valves for any cam other than that of the stock cams? I saw a 272 cam that said "Designed to bolt into a stock engine to increase overall performance. Stock fuel injection OK." Is that true of all 272 cams or is what they say simply crazy? I am not a big valve train and what not guy, but I know a good cam can make a car or break the car. So all help is greatly appreciated.

 

[awdtalontsi1992]

Unless specifically specified by the cam manufacturer you don't have to change anything on the head except the cams themselves. This includes 272s. A nice set of dual valve springs and Ti Retainers would be nice but not required.

 

[IceDragon]

Some manufacturers (sp?) don't say anything at all weather it is okay or not, and some haven't even emailed me back yet when I asked. So would the comp cam's 264/272 combo need any type of upgrade??? I ask because they are the only set I can get at my work unfortunately. And I was also wondering if 272's give a bad idle only becuase of the low compression of turbo cars... or would I still get the same rough idle on a car running anywhere from 9:1 compression to 11:1 compression? I am new to the actual engine modifications like this, so all of the help is appreciated, thanks.

 

[fourreGsixty3]

Fist Comp doesn't make 264272, that would be HKS, and DKS that use that name, Comp's are 101100s, 200s, 300s, and 400s. 264/272, won't need anything done to the head or valvetrain. The 272s wont need anything. The 280s that HKS, and BC offer they say to upgrade the springs, and retainers, but this is only to cover their asses so you don't drop these aggressive cams into a head with over 100k, and expect nothing to break. 264s will have a stock feel idle to them, 264/272, will have a very negligable difference to idle, the 272s will have a little worse idle them stock, but its not bad at all. I wouldn't be too worried about idle unless you are dropping straight race cams into your head. Thje 264/272 will give your turbo more breathing in the upper rpm's, and take little to nothing from the bottom end, and give you a nice linear power gain through the whole range, and allow you to make more power past 6800rpm's, where the stockers are pretty usless after, not saying stockers can't make power past this point, and that you can't take them past this point because I take mine to 7k, but the upgraded cams will make more power past that point.

Dustin

 

[IceDragon]

That's the thing fourre, I am runnin the stock N/T compression ratio. I am not turbo yet, but I am slowly building up the engine while still needing it to drive throughout the week, so weekends are project days. That is why I am wondering how the 272's would effect the idle on a 9:1 comp ratio engine. And ontop of that, how much good would they honostly do to a non turbo engine? Granted I have in the stock turbo cam's right now in my n/t and that is a good feel up high with a small difference in idle, on very cold days, when it is still warming up. That is why I am asking about the 272's being a good choice on an N/T?

 

[gixrman]

Turbo cams in a NT is a big no no. The duration is way to much and will kill any vacuum that you have. You need NT cams.

 

[IceDragon]

Any recommendations than gixrman? I saw gude has a "performance package" for the N/T, but the price seems too good to be true.

 

[nightspeed87]

That's the thing fourre, I am runnin the stock N/T compression ratio. I am not turbo yet, but I am slowly building up the engine while still needing it to drive throughout the week, so weekends are project days. That is why I am wondering how the 272's would effect the idle on a 9:1 comp ratio engine. And ontop of that, how much good would they honostly do to a non turbo engine? Granted I have in the stock turbo cam's right now in my n/t and that is a good feel up high with a small difference in idle, on very cold days, when it is still warming up. That is why I am asking about the 272's being a good choice on an N/T?

i dont see how compression matters as far as cam idle. If it does explain.
And I believe anything greater than a 272 cam will starting messing stuff up in the head.

Turbo cams in a NT is a big no no. The duration is way to much and will kill any vacuum that you have. You need NT cams.

And putting n/t cams on a fairly stock turbo car doesnt hurt, and putting turbo cams in an n/t wouldnt either. Only thing is , turbo cams have less overlap from more backpressure
so Id say youd be gaining top end with the turbo cams, but loosing some mid range torque and what not. Im not sure the gain/ or loose of using turbo cams on a n/t though.
As far as it loosing vacum, not sure about that statement.

 

[IceDragon]

well nightspeed, i just figure since stock 1g is what, 7.8 or 8.5 or something for a turbo car's compression vs the n/t running 9, than it would make a slight difference in not only power and where in the rpm's the powerband would reside, than I believed that since 9:1 compression would bring in more air "slightly" at idle, than maybe it wouldn't mess the idle up all that much as it would on the lower compression.

 

[nightspeed87]

well nightspeed, i just figure since stock 1g is what, 7.8 or 8.5 or something for a turbo car's compression vs the n/t running 9, than it would make a slight difference in not only power and where in the rpm's the powerband would reside, than I believed that since 9:1 compression would bring in more air "slightly" at idle, than maybe it wouldn't mess the idle up all that much as it would on the lower compression.

No I dont think that will be a factor. Stock turbo 1g is 7:8/ 2g is 8:5. I have 2g pistons in my car and it doesnt affect idle. Idle has to do with t/b position, and low vacum , obviously cams, intake manifold upgrade, etc. will affect idle. Compression just has to do with how much is compressed during the stroke in a blunt way of saying it.

People think you cant run 9/1 comp ratio or higher on a turbo car which isnt true.
Its all about egts and tuning really, i mean on race gas im sure you could get away with 9:5 compression on 20lbs of boost or more supposing your timing is at an acurate adv.

Its not usually typical for turbo cars to run that much compression because the ring lands are higher and knock would be more likely and more devastating. High comp on turbo engines is normally for hardcore tuners, i mean for the slight gain of power but large gain of knock chances. Not worth it to go higher than 9:1 for a turbo car in my opinion, but personally the 8:5 I have is ok, wouldnt want to go much higher than that. If your looking for real drag type power get like some 7:1's and run ridiculous amounts of boost on them while getting away with as much timing adv as possible.

IceDragon, whenever you go turbo, you wont have to change out your n/t pistons unless you have other problems in the engine, but if you have a perfectly good n/t engine. Slap on the stock turbo set up, buy a eprom 1g tubro ecu , get it keydiver chipped from www.dsmchips.com and tell jeff you have 9:1 comp ratio and he'll adjust your timing according to that and youll be good to go. OH and get a knock sensor and logger. Youll feel like your car does now off boost but on boost youll be much quicker.