CAMS!CAMS!CAMS! RUN!

[Steentong]

Looking into cams, dont worry i did a search, and i will only touch upon unusual and specific questions i have.

MY STORY: Im looking into full race cams. 270 duration and up! This means I have to use new stiffer valve springs. Idle is little to no concern to me, currently my car idles at 1200(worn spring on throttle), I dont see any problem with that!(after all who else would drive a car without power steering if they were'nt serious about peformance)
MY APPLICATION: If you already havent guessed these are for a 2.5 Gt engine. Nitrous may come into play here. Yet I would perfer that the redline be booted up as high as possible.
MY SEARCH AND QUESTIONS: Okay heres what im looking for. I want some 270(or plus) duration cams, Much higher lift, and some new valve springs. Is interept my only solution?

Thanks and be brutal

[crazyprobe]

you should check into the coltcams wild cams.

they have 0.365L and 274duration. should be what your loooking for.

[StreetThisMX6]

full out race cams ususally raise the compression a lot. like to 12 to 12:1..i didn't that it was that good to run nos with high comression motors..it is the same way to turbocharging...if u want info on cams go to www.paeco.com and order there catalog..it kicks asss and has ton of motor performance parts for are car...

[Steentong]

Crazy Probe that is a very desirable cam. Do you utilize new valve springs? If not how do you prevent valve float? I would be very intrested in ordering some colt cams from you and sticking them on the dyno the next day!

I have dynoed right now at 149 hp(5500 rpm) and 150 torque(at 4500).

Are you intrested in letting me borrow them for a couple of days for testing. I'll throw it on the dyno, Do a run pre cams, then do a run with the cams. Then ill buy them when i see how much of a diffrence they make. :grin:

Then ill post all the dyno plots and information in here and in the pic post.

That way I can get some kick ass cams, and you and colt cams can get some definate numbers to advertise.

Thoughts?

[SePHiRo]

Interprep race grinds are 280 lift and 9.4 duration, street grinds are 270/8.9

I don't know of anybody with the race grind or even a dyno of it, but you should see them for the first time in 1 or 2 weeks dyno'ed *hint*

[SePHiRo]

Interprep race grinds are 280 lift and 9.4 duration, street grinds are 270/8.9

I don't know of anybody with the race grind or even a dyno of it, but you should see them for the first time in 1 or 2 weeks dyno'ed *hint*

[Twenty36_1]

On Sunday December 2, 2001 5:30 PM, SePHiRo wrote:
Interprep race grinds are 280 lift and 9.4 duration, street grinds are 270/8.9

I don't know of anybody with the race grind or even a dyno of it, but you should see them for the first time in 1 or 2 weeks dyno'ed *hint*

I have them, well waiting to receive them. Should have a dyno end of Dec.

My combo:

P&P'ed heads manifold
Bored TB
10:1 CR
Fidanza
ACT HDSS
All bolt ons

[FRCFD6]

On Sunday December 2, 2001 11:17 PM, StreetThisMX6 wrote:
full out race cams ususally raise the compression a lot. like to 12 to 12:1..i didn't that it was that good to run nos with high comression motors..it is the same way to turbocharging...if u want info on cams go to http://www.paeco.com and order there catalog..it kicks asss and has ton of motor performance parts for are car...

mm'kay......my lead-foot increases the octanelevel of the the gas i run.......how can cams "INCREASE" compression ?....the only "INCREASED" compression you will see, is the added compression on the valve springs....

[Drag On]

On Monday December 3, 2001 7:01 PM, FRCFD6 wrote:

On Sunday December 2, 2001 11:17 PM, StreetThisMX6 wrote:
full out race cams ususally raise the compression a lot. like to 12 to 12:1..i didn't that it was that good to run nos with high comression motors..it is the same way to turbocharging...if u want info on cams go to http://www.paeco.com and order there catalog..it kicks asss and has ton of motor performance parts for are car...

mm'kay......my lead-foot increases the octanelevel of the the gas i run.......how can cams "INCREASE" compression ?....the only "INCREASED" compression you will see, is the added compression on the valve springs....

Thats what I was gonna say.. But I figured I'd leave it alone.. Cams will not change the compression..

[crazyprobe]

yeah interprep's cams are advertized at
0.350Lift and 270ad. duration (still a stock idle that's weird)
0.370Lift and 280ad. duration (need stiffer springs to prevent valve float)

I was ganna pick up a set to put through the computer but $600us is just to much moeny to find out what the specs really are.

[mikeseli]

You guys need to understand that as duration is raised for both intake and exhaust cams, so does overlap period.

This overlap period will affect your idle quality and as well your low end power curve, with 270 duration cams you'll lots of power(Hp & torque) below 4000rpm which is where most of the time your at.

I wouldn't suggest the 270 deg cams for everyday driving, especially on a automatic car.

Mike S.
PGT-ZE
184whp

[mikeseli]

On Tuesday December 4, 2001 3:36 PM, mikeseli wrote:
You guys need to understand that as duration is raised for both intake and exhaust cams, so does overlap period.

This overlap period will affect your idle quality and as well your low end power curve, with 270 duration cams you'll lots of power(Hp & torque) below 4000rpm which is where most of the time your at.

I wouldn't suggest the 270 deg cams for everyday driving, especially on a automatic car.

Mike S.
PGT-ZE
184whp

I noticed, I forgot a word.

With the 270 deg cams you'll loose lots of low end power, especially below 4000rpm, just have a look at the latest dyno plots from ProbeGTR.

[Daemione]

how can cams "INCREASE" compression ?....the only "INCREASED" compression you will see, is the added compression on the valve springs....

As far as static compression ratio, you are correct. The only way that is altered is by changing the physical dimensions of the combustion chamber.

Cams will, however, change effective compression - which is a lot more important than static c/r. But it's not done in an easily measurable way.

A hot n/a cam will usually leave the intake valve open longer, to allow mixture to continue entering the cylinder during the start of the compression stroke. This means that more air/fuel is forced into the cylinder (ideally achieving greater than 100% volumetric efficiency). When the intake valve snaps shut, it traps the extra mixture in the cylinder before it begins to get pushed back out. With more air/fuel in the cylinder, pressures are increased - hence a higher effective compression ratio, more power, and a greater chance of pre-detonation.

Of course, adding in the longer duration of the exhaust cam affects things as well. Depending on how it's timed, it can either increase or decrease effective compression.

It's somewhat of a black art, and I don't know enough of the specifics to say exactly how compression will be changed. But I know enough to say that cams can change your compression ratio.

[Twenty36_1]

On Tuesday December 4, 2001 8:37 AM, Daemione wrote:

how can cams "INCREASE" compression ?....the only "INCREASED" compression you will see, is the added compression on the valve springs....

As far as static compression ratio, you are correct. The only way that is altered is by changing the physical dimensions of the combustion chamber.

Cams will, however, change effective compression - which is a lot more important than static c/r. But it's not done in an easily measurable way.

A hot n/a cam will usually leave the intake valve open longer, to allow mixture to continue entering the cylinder during the start of the compression stroke. This means that more air/fuel is forced into the cylinder (ideally achieving greater than 100% volumetric efficiency). When the intake valve snaps shut, it traps the extra mixture in the cylinder before it begins to get pushed back out. With more air/fuel in the cylinder, pressures are increased - hence a higher effective compression ratio, more power, and a greater chance of pre-detonation.

Of course, adding in the longer duration of the exhaust cam affects things as well. Depending on how it's timed, it can either increase or decrease effective compression.

It's somewhat of a black art, and I don't know enough of the specifics to say exactly how compression will be changed. But I know enough to say that cams can change your compression ratio.

I don't know about this, By saying this you also mean that a turbo or super charger will change the CR right? (I know you said not static CR) Since more air will be in the combustion chamber on one intake stroke. Please elaborate, right now it doesn't really make sense.

[Daemione]

I don't know about this, By saying this you also mean that a turbo or super charger will change the CR right? (I know you said not static CR) Since more air will be in the combustion chamber on one intake stroke.

That's correct. Forced induction increases the effective compression hugely, which is why it makes so much power. And with more fuel/air in the cylinder, the mixture is heated up more during compression, which is why FI motors often start with a lower static C/R to avoid detonation.

However, with good piston & combustion chamber design, along with accurate fuel tuning, a forced induction engine can have no problems running at fairly high static compression ratios - and still have respectable off-boost performance. For example, with stock internals & good fuel tuning (i.e. Hondata), Integra Type R's have been known to run up to 8 non-intercooled psi, at 10.6:1 static compression, on 91 octane gas.