Best cam for 80% Street, 20% track?

[Steve Wood]

Originally posted by REDS HOT AIR


when the blades break off the exaust wheel..

Hey, they become really efficient then! No back pressure and that exhaust really opens up!

 

[quickt]

There are so many sides to this subject it almost always ends up in a pissing contest. I will say this much. I have seen many cars with smaller cams example 206/206 go very fast. I have also seen big and small cam cars that would not fall out of a tree. For me I have gone faster everytime I have stepped up in cam size. I have picked up 60ft and MPH and lowered my ET. Unlike many others I have seen .2 from a cam change. So from this side of the fence I am sold on the larger split pattern cams that favor intake lift and duration. IMO what ever works for you then use it.

 

[SideSlip]

Lots of excellent info........never realized the can of worms I was opening. However, to get back to my original post.......lets say I have a TE-60, 2800 stall, 009's, fuel upgrades, and exhaust........do I get a cam that favours exhaust or intake, taking into account the 80% street/20% track ratio????? And how much duration and lift for a resonable idle????? (or generally good street manners) I know there's a lot of "magical physics" involved, but what has worked well for you guys? Thanks.

 

[REDS HOT AIR]

cant remember who said ..

that you get more reversion from longer duration on the exaust???

no more than longer duration on the intake UNLESS the lobe seperation angle is opened up so that the valve over lap dont get too crazy.


other words that has to do with valve overlap which is controled more by lobe seperation angle

so if you take a 206-206 cam with 114 lobe spread and then you take one with the same specks but ground with 110 degree lobe spread then you have more overlap and reversion

 

[Steve Wood]

Originally posted by quickt
. IMO what ever works for you then use it.

Pretty hard to argue with that. One thing about it, if something works well, someone can always invent a new theory to explain it.

Reality is fact, theory is not always.

 

[Steve Wood]

Originally posted by REDS HOT AIR


other words that has to do with valve overlap which is controled more by lobe seperation angle

so if you take a 206-206 cam with 114 lobe spread and then you take one with the same specks but ground with 110 degree lobe spread then you have more overlap and reversion

I would have thought that was obvious. However, it is skewing the reversion process somewhat to throw overlap into the equation.

Reversion occurs when the exhaust backs into the cylinder past the valve. If the valve is held open long enough so that exhaust back pressure is greater than cylinder pressure, exhaust gas will back into the cylinder. Overlap will have little or not role.

Overlap can be beneficial on an n.a. engine as the exiting exhaust gas may help pull a fresh charge past the intake valve at higher rpms. In some cases, we may even put a lip at the exhaust port outlet to discourage spent gases from backing up into the cylinder when the piston moves down on the intake stroke.

With a forced induction system, such as we run, exhaust backpressure is a much greater factor in the reversion process and, in theory, at least, exhaust timing and cylinder pressures must be weighed against the backpressure curve versus boost.

As we know some cars run well with extended exhaust durations, combination must be the deciding factor. What we may not know is how well it may have run with a shorter duration/different combo.

That's what keeps this interesting.

 

[turbocharged87]

Let's forget the cam thing for a second. Someone needs to help me tune another 1.5 sec's off my 10 sec. combo I supposedly have on my car. How many of you out there have a stock intercooler car running 10's ? Is it possible to run 10's with a stock intercooler, 15psi , pump gas and street tires? Any help would be great as not to waste money on a front mount or race fuel or slicks. Thanks in advance

 

[azgn]

10's on pump gas, 15 psi, street tires & stock IC? Hmmmm...kinda doubt it.......well, maybe if you are Red Armstrong.......

oh..you meant the 1/8 mile, right?

 

[86brick]

I know of a guy that ran 10.03 @134mph with a stock intercooler that was modified with a cool box I would suggest you get a Tony DeQuick CAS V4 stock location stretch intercooler (21 row) rather than a front mount cause a FM will cost you about $1k new and unless the cooling system is upgraded the engine temps will increase by about 10 - 15 degress. For a new 3 pass radiator and dual spal fans you'll spend about another $800 - $1k. Race gas and slicks are needed, although, some have run 10's with pump gas and alky.

 

[azgn]

who has run 10's on pump gas & alky?

 

[86brick]

Woody, Dennis Hogan ran 10.97 on pump gas and alcohol a while back. He's a good friend of Geno's and Geno posted it in the Alky section a while back. I did a search and found it. The car had a PT52 turbo, V4, 50's, GN1 aluminum heads, 208/208 flat tappet cam, and he was running a 20deg timing chip with 22lbs of boost. If you'd like do a search on Dennis Hogan and I'm sure you'll find it I know of a certain silver T-type down in the Fort Lauderdale area that ran 11.30's @119mph with a 1.62 60' with 20lbs of boost on pump gas and alcohol and I'm sure blackshoebox (Alex) will get this car to run in the 10's with a better launch and a little bit more boost

 

[azgn]

very interesting

 

[86brick]

Yeah, I think high 10's is very possible with pump gas and alcohol IF the car has good flowing heads and intake, a bigger cam, and a good size turbo, although, a PT52 isn't areal big turbo. Bottom line is the car better run good with about 20-22lbs of boost cause anymore than that and you'll pushing it with pump and alky IMO.

 

[UNGN]

Originally posted by turbocharged87
Let's forget the cam thing for a second. Someone needs to help me tune another 1.5 sec's off my 10 sec. combo I supposedly have on my car. How many of you out there have a stock intercooler car running 10's ? Is it possible to run 10's with a stock intercooler, 15psi , pump gas and street tires? Any help would be great as not to waste money on a front mount or race fuel or slicks. Thanks in advance

Your combo is a "ten second combo" IF you run race gas and a race chip and high boost. Who said anything about 15 psi and Pump gas? Even with a stock intercooler, the TA61/3" downpipe/ported heads and huge cam could run very, very, very low 11's. 12.48@109 is stock turbo territory.

With race gas and a race chip my car has run 9 mph and .9 faster with a much smaller turbo, completely stock motor (heads, cam pistons), smaller injectors, on radials with the stock intercooler and there are people a lot faster than me. The ported heads, big turbo, huge cam and loose converter shoud go along way towards picking up the other .6 seconds. I would hope, atleast, otherwise what good are they?.

It's not "wasting money" on race gas if you go faster without spending a lot of money on mods... it's "investing" in race gas. If I had the choice of spending $20 on race gas when I go to the track or spending $1000's on mods to run as quick on pump gas, I'll keep buying race gas. That's just my personal opinion, however. Everyone is different.

 

[Steve Wood]

Originally posted by turbocharged87
Let's forget the cam thing for a second. Someone needs to help me tune another 1.5 sec's off my 10 sec. combo I supposedly have on my car. How many of you out there have a stock intercooler car running 10's ? Is it possible to run 10's with a stock intercooler, 15psi , pump gas and street tires? Any help would be great as not to waste money on a front mount or race fuel or slicks. Thanks in advance

Well, you are losing .5 in the quarter with your short times.

Then you need a good race chip, race gas, boost, and a V4.

Don't want buy race fuel and slicks? Find another hobby or settle for upper 11s with alky.


I would like to run 9's on pump gas and tires but sometimes we have to be realistic.

 

[c&cgn]

Originally posted by 86brick
Woody, Dennis Hogan ran 10.97 on pump gas and alcohol a while back. He's a good friend of Geno's and Geno posted it in the Alky section a while back. I did a search and found it. The car had a PT52 turbo, V4, 50's, GN1 aluminum heads, 208/208 flat tappet cam, and he was running a 20deg timing chip with 22lbs of boost. If you'd like do a search on Dennis Hogan and I'm sure you'll find it I know of a certain silver T-type down in the Fort Lauderdale area that ran 11.30's @119mph with a 1.62 60' with 20lbs of boost on pump gas and alcohol and I'm sure blackshoebox (Alex) will get this car to run in the 10's with a better launch and a little bit more boost

It was a comp 206-206 cam but other than that the rest is pretty accurate. I would suspect he used more boost than 22psi though.

 

[1badTTA]

I would have to agree with UNGN that with traction, higher boost, and hogher octane that 1.5 seconds isnt unrealistic. My car (see sig) has run 110.21MPH with drag radials and 105 octane blend of gas. This is with mostly stock parts (had a postons GN110T cam in it at the time, but the #1 exhaust lobe went south and I still had the stock cam laying around so it went back in and I think it runs better now (there, I contributed to the original thread topic)) and I am interested what it will do with the stock cam.

 

[AsphaltAnihil8r]

Originally posted by Steve Wood


Hey, they become really efficient then! No back pressure and that exhaust really opens up!

With less blades was there less Drone:: Sorry had too..

 

[86brick]

c&cgn, when I did a search on Dennis Hogan in the Alky section Geno posted his combo and from what he said the car did have a 208/208 flat tappet cam with T&D 1.55 roller rockers. He also stated that he was running 22lbs of boost with a JL 93 chip with 20deg of timming. I'm just going by what he stated in the post I think the GN1's helped that car run so well with only 22lbs of boost with the PT52 turbo, although, his mph was kind of low for a 10.97 car IMO (122mph).