This is a graph illustrating two combos that have been dyno tested. The first combo is a hydraulic roller, second combo uses a hydraulic flat tappet. Same heads and compression ratio on both.

First combo makes more torque and HP comes in earlier, but flatlines after 5k.

The second combo makes more HP, but less torque and the HP is closer to the 6k range.

Don't know which one I want to use. This is for a naturally aspirated street/strip car.

I'm thinking, 400 or so crank horsepower in a 3200lbs car should break into the 11s, no ?

-- Joe

 

for a street car i'd pick the roller, lots more power where you can use it. i'd also say low 12s for a time

 

Probably going to be a sunday car, that will see a lot of track time. I don't even expect it to have an overdrive. I want to build something to get into the 11s, but not on a lot of dough.

I'm not sure yet what I want to use for a body. Thinking either a early 70s C3 or a late 70s 2nd gen f-body. The 2nd gen would probably be a better track car with the solid rear, though the C3 would be nicer looking.

-- Joe

 

I run a hydro Flat/tappett in my street strip car. It hasn't given me any problems yet. It performs well too. It is an animal on the street.

 

What is the specs on the whole build? nice et!

-- Joe

 

no reason to run anything but a roller these days, you never have to worry about eating a cam lobe because of new oils lacking certain things or breakin. Same size roller will always make more power than a hyd. flat tappet as well due to the more aggresive lobes.

 

As long as you dont want to go over 6500 i would say go with a hyd. roller. If you want to turn more than 6500 rpm's i'd go with a solid roller simply because you dont have to worry about valve float and using a hydra rev and having lifters come apart and what not.

i hate to use this example, but there are plenty of ls1 guys running solid rollers in streetable applications.

 

True.

The unfortunate problem with a hydraulic roller is the cost.

First you need a block.. $200 or so, then the cam is on average $100 more, and lifters on average $100 more.

While it sounds petty, it could add $400-500 to the cost of a build, for a net gain of only a few HP and some peace of mind.

-- Joe

 

No offense but then why ask the question if your mind is made up? I'd reuse the stock lifters if you're not building a crazy combo. Ask me how much it was to remachine a motor when I ate a lobe during break-in of my flat tappet cam and the extra $100 for a roller cam isn't the issue.

 

My mind isn't made up. I'm asking what folks think of the power curves. Not the roller vs hydraulic issue. Just the two very different curves.

I may very well use a hydraulic roller, but my question was more towards which cam profile looked better.

I've never ruined a cam before during break in, but I've heard of a few guys on here that have had it happen. What do you think caused it?

-- Joe

 

Luck of the draw IMO, I have broken in probably 50 motors with solid flat tappets and in my own car it decided to eat itself. If the lifter doesn't being to spin immediately upon fireup, that's all it takes and the lobe starts to go flat. No sense to run anything but a roller cam anymore, the cams will make more power. I'd rather have a lower peak rpm that makes more torque since it'll be easier on the engine.

 

ding ding ding we have a winner

 

I skipped over a lot of this argumnet but just wanted to ad that a lot of people preach that Roller Cam is the ONLY way to build a motor. I can easily preach the same thing. However, money rules this hobby. If you have it, you have it.....If not, you're getting a Flat tappett.

I went Flat tappett. $110
Mine is 241/246 @ .050 and with 1.6 rocker it's .537/.540. It is very streetable, has a great sound, and was inexpensive. It made peak HP at 6200 and fell off at 6500. With a 3300 stall and 4.10's it runs 11 flat.

Worst part of Flat tappetts is break in. I felt like a ***** in church for the first couple minutes. There are a lot of write ups on what to do. I was told by Tony Mano of AFR the correct way step by step. There are still zinc racing oils available and break in lube from comp as well.

I will go Hdro roller next motor but this one works well.

I think my cam is Comp XE-284-H or something.

 

It looks loike both of those cams would probably have the same et, probalbly a little different mph. If your combo was optimized, it would probably run a high 11, low 12 with 400hp and 3200 lbs. If your driving on the street, the extra torque is nice, for the track, hp is nice. Also if you want it to run solid in the 11's, your going to need at least 450hp. a cam alone wont net you that extra 50 hp, depending on engine size, cylinder heads, etc. Im also partial to roller cams.