cams vs. increase boost

[Spades]

What advantages are there with upgraded cams vs. increasing boost? From what I've read it seems to be that the cams will broaden the power range with quite a bit of an increase in hp, but wouldnt a larger turbo do the same if not more?

 

[Black_Bullet]

They both increase airflow and thats your goal to making more power... Higher boost and the turbos working harder to provide more air, bigger cams and the motor is digesting the air quicker. Simple as that.

 

[MaNGiNa24]

If you just have an upgraded turbo you'll eventually hit a bottleneck in power until you upgrade the cams.

Personally I think they are one of the best bang for your bucks mod, especially when you can get something as inexpensive as the BC 272's and make an extra 30 - 40whp while broadening your power range

 

[tkelly27]

Kind of dumb, but if you imagine the engine swollowing boxes of air, you can either get it to eat bigger boxes, or squish more into those boxes. A problem with squishing more into the boxes is that you get higher pressures inside the combustion chamber, also there is generally more heat put into the charge air with the more you compress it. Another thing camshafts can do is push torque production higher up into the RPM range, increasing peak power. They aren't mutually exclusive as turbocharger, camshaft, intake manifold, and everything else works together to create an engine. Many people still go fast on stock cams though.

 

[pboglio]

I'm using Dyno 2000 to simulate some popular cam grinds offered to DSM owners. I modeled the difference between HKS 264/264, HKS 272/272, and FP4R cams. At the same boost levels the more agressive cam is putting out nearly 80 h.p. more then the milder HKS cam, so long as the turbo compressor can kick out enough airflow to support the power increase. At WOT there is practically no compromise in torque, all gains happening above 4000 rpms to and beyond 7000 rpms. This is exactly what I saw with my HKS 264/264's, about a solid 20 h.p. gain with gains starting at 4500 rpms up to redline.

To get those same gains on a turbo upgrade you'd have to increase the boost level about 8psi to do it. The problem is the gains are centered much more around the midrange with boost increases and tapers off well before redline. IMHO both boost increases and cam upgrades complement each other in different parts of the power band.

 

[dsm-onster]

Broader powerband and more peak power are good points. A good cam upgrade gives you higher VE in the stock powerband and increases VE at higher rpms. Higher VE at higher rpms makes more horsepower, more airflow per unit time.

To add to the above. . . Higher boost increases intake manifold air temps greatly. Much moreso than running a compressor off the map even. It may take 8more psi of boost to match a good cam upgrade, which you may be able to get away with your current turbo. But can you do it with your current fuel? The higher intake temps mean that fuel that curbs detonation better may need to be used. If you can up the boost 7-8psi, you may have to invest in a water injection kit or run much more expensive race fuel, which really adds up in costs for a frequently driven car.

Cams give you more power with the same fuel, mostly. It does increase cylinder pressures and thus changes MBT, thus you may need to retune for best power without knock, but the gains will still be there with pumpgas, where too high of a psi autmatically rules out pumpgas unless you pay for water injection.

 

[pboglio]

This is clearly why guys who run fairly good sized turbos like 50 trims and FP3052s etc don't produce the numbers they should. The cams are holding back the turbo big time. I'm a proponent of cams first, then big turbo second. I'm not a huge fan of running megaboost since it just closes down the turbine section and generates a crap load of backpressure plus you have to start running race gas or meth injection as mentioned already.

I'll be going to the FP4R's on my T28 and hopefully the 5 degress of overlap won't cause too much knock. Hopefully I can pick up about 35 h.p. on the midrange and topend.

 

[Spades]

I think im sold on getting cams as my next upgrade I just put a new rebuilt engine 6 months ago and I was debating whether to do it then. I do have water /meth injection and am on an FP Big28 set @ 18 psi, I know I can push around 22 psi for more power but I think Id rather do the cams because I love the lightning quick spool up and it'll keep my turbo nice and relaxed @ 18.

 

[z24frank]

Now what if you want to increase your low end rpms are ther cams set up for this?And on another note talking about money spent when upgrading,Dont you have to change the springs and retainers when you do cams all this cost money as well!

 

[daren_p]

This is clearly why guys who run fairly good sized turbos like 50 trims and FP3052s etc don't produce the numbers they should. The cams are holding back the turbo big time. I'm a proponent of cams first, then big turbo second. I'm not a huge fan of running megaboost since it just closes down the turbine section and generates a crap load of backpressure plus you have to start running race gas or meth injection as mentioned already.

I'll be going to the FP4R's on my T28 and hopefully the 5 degress of overlap won't cause too much knock. Hopefully I can pick up about 35 h.p. on the midrange and topend.

Wow, that a pretty "big" cam for a pretty "small" turbo. Defently interested in seeing the resaults of that. That poor little T28 won't be able to keep up by 5500rpms (though I think there was mention of a 3052 in the future? That would be an excellent combo )

 

[pboglio]

Wow, that a pretty "big" cam for a pretty "small" turbo. Defently interested in seeing the resaults of that. That poor little T28 won't be able to keep up by 5500rpms (though I think there was mention of a 3052 in the future? That would be an excellent combo )

Yeah, it is a pretty big cam. Its a good opportunity to get some data points on a small turbo before I go bigger. Curt Brown commented on the hefty power increase over the HKS 272's using FP4R's and he sounded very content with them. I've seen the AMS EVO cam shootout and the FP4R's gained 25 w.h.p. midrange/10 w.h.p. peak over the HKS 272's with very little loss on the low end on a GT35 turbo @ 22 psi.

It's also gonna be wicked expensive: cams, springs/retainers, adjustable cam gears, 3g hydraulic lifters, valve spring tool, misc. Doing it right looks like $1500, if I cut corners and just do the cams and springs its maybe $800.

 

[z24frank]

I have a question on the 3g lifters is there any thing needed to do this or just drop them in?