Cams in my "street car"

[selmerguy]

I am curious as to when the stock cams are hurting your power. At what level of HP do the stockers give up? I have been driving my car around on WEB 546/547 cams for a few years. I dont want to say I have problems with them but.... They do take something away from street driving. When I instlled them I loved them. Now, not so much. I miss seeing 20 Hg vac at idle. I have been thinking lot about my "goals" for my talon and I want the best of both worlds. I want a bad ass street car. I am going to do a rebuild when I get home. And install a Holset H1C turbo with the BEP .70ar housing. I want somewhere in the 400 HP, that is it. Can I do this on stock cams? Where will they start hurting me in the power band?


Sam

 

[TunaTalon]

AMS performed and published a comprehensive DSM cam test a few years ago.
My link to that test is dead but Google found Ams Evo Cam Test - evolutionm.net while looking for it.

This looks promising and is still in progress.

 

[1992awdlaser]

The thing with stock cams is the power will drop off sooner than with aftermarket cams. It's not really about the power being made because they will drop off regardless of how much power you are making.

 

[thilaksharma]

AMS performed and published a comprehensive DSM cam test a few years ago.
My link to that test is dead but Google found Ams Evo Cam Test - evolutionm.net while looking for it.

This looks promising and is still in progress.

Automotosports

 

[RipperXX]

I would just go with a good set of mild cams, like HKS or GSC, afterall thats what I am doing and I have a very similar goal to you, I am building my car to be more for canyon carving/acceleration on the streets with a goal of 380whp off an Evo III.

I was fairly set on a set of HKS 264 cams until I noticed AMS's testing on the DSM 4g63. Now I am more set on a pair of GSC S2 cams. Better top end without really losing any low end.


This will help keep the car street friendly and fun to drive, (as well as reduce lag) but not have the same fall on your face drop off the stock cams have.

 

[romeen]

When choosing which cams you want keep in mind which turbo they will be used with so that you will be maximizing VE for that particular turbo's power range. Cams which work really good for one particular setup may not necessarily be ideal on another setup.

 

[dsm-onster]

Cams and cam timing can change the "powerband" of a turbo . Example, stock cams spool a 50trim to 20psi by 3500rpms. But with 272s a 50trim can see 20psi as late as 4500rpms.

I'd choose a cam for your prefered style of driving first. Then choose a turbo that will spool the fastest while still flowing enough overall (compressor and turbine) for your goal.

As mentioned stock cams don't just cut off. You can still make good power with them if you have a turbo that likes LOTS of boost and plenty of race gas/injection. But what a cam upgrade does is give you more flow with less boost neccesary. And changes VE in particular rpm ranges. If you like street driving and cornering without downshifting, lower duration is for you. Because lower duration helps improve cylinder filling at lower rpm ranges. But you will have the power dive as you go higher in the revrange. Higher duration gives the engine better cylinder filling when the engine can draw more mass per sec. Lower VE at this point (small duration) will go against one whose goal is higher horsepower and drag racing. More potential mass flow from higher rpms coupled with higher cylinder filling per revolution means quite a bit more power peak.

If you want the best street manners, then stock cams are for you. But there is a sacrifice. As mentioned you'll need to run more boost to overcome the lower lift and poor cylinder filling after the power band. Depending on your goal, because of the heat that higher boost may generate you maybe limited to high octane fuel to reach a horsepower number.

Get your cam card for these cams and give us the duration @ .05" lift, and the centerlines and we can tell you what cam would feel more streetable than those to you. . . I am under the impression that you have web version of 272s and fp1s, hks264s, or 264 reginds would be for you.

Adjustable cam gears can give you more street fun with your cams. Advancing the intake cam will help lowend responce and spool. Retarding the exhaust cam will help spool and maintain most of the high end the cams are designed for.

 

[romeen]

Good stuff Matt, and thanks for the clarification.

 

[TurboAnything]

I have stock cams in my motor with a S258 and i dont feel a huge drop off in power and i go up to 8000rpm. I just love having a good idle and power down low thats why i have not switched out yet.

 

[dsm-onster]

Stock cams and a td05h 18g was SO very fun! The 18g didn't fall off in boost at redline. I was running 24ish psi at that point in time. I was seeing 38lbs/min by 5700rpms, 39lbs/min from 6000rpms to 7000rpms. 31lbs/min by 5000rpms. Very flat. And it hit so fast that when I let my wife drive, she pulled over on the highway and gave me back the keys. But when I swapped in 272s she drove it to work everyday not knowing that after 5500rpms was the same 38-39lbs/min. The cam's really determine the nature of the engine.

I like 264s on the street. Still have that hard hit at 3K but don't shy away at 6K. And the lift really helps not needing so much boost. Stock dsm cams have very low lift vs. many other 4 cylinders. Stock lift in the s14 sr20det is right around the lift of fp2s. The stock 4g63 cams do have decent duration for m/t 1992+.

The best stock cams are a significant upgrade in lift to all the others: the B, C cams. Stamped on the back end "D" for the intake and "C" for the exhaust. Turbo cams for the 1993-1994 manual DSM. They have a valve lift of .37" (lobe width of 1.3972", stock 4g63 base circle 23/128", stock 4g63 lifter ratio of 1.7). They have 252 duration at .00" lift (begining of lobe).

 

[TunaTalon]

Yes indeed dsm-monster cams change the nature of the car, and 264/264 cams really perk up the low end compared to the stock cams. But that’s just me. Other people with other goals will want to compromise some low end response for more power when on a full boil. With all of the cam test dyno charts linked here anyone can make the compromises to suit their own goals.

In my Talon all compromises were made in favor of low end/ mid range response. I selected 264/264 cams based on the following chart from the AMS cam testing. I get immediate punch off of the green light and still have a good top end.

One caution on adjusting cam gears on an automatic transmission. With the high stall torque converter the engine did not spend enough time on the dyno in the low end to allow adjusting the gears.

 

[dsm-onster]

With the high stall torque converter the engine did not spend enough time on the dyno in the low end to allow adjusting the gears.

Damn good point! Stock stall would be one thing. But with the capabilities of a high stall, the issue of building boost as quick as possible is not as valuable. A good high stall torque converter is like antilag without the nasty sideeffects. Big cams love high stall.

 

[selmerguy]

Wow. Thanks alot for all that great info. The links helped alot. I have tons more think ing to do about cams and turbo choice for my upcomming build.