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Author Topic:   performance advantages
RangeRover
Dirt Full Roller

Total posts: 37
posted February 22, 2001 09:09 PM
In a 2 barrel class with a hydraulic cam rule and 3300# minimum weight, how is that group of guys running away from everyone else? Do stuff like Rhodes lifters and Brzezinski-worked heads make that much difference? What about carb improvements that don't raise flags in tech? My team and I feel that we have done our homework and have our car working pretty good with our track rules, but we're missing something; our engine doesn't even sound like those guys'. We have come to the conclusion that it's time to step it up, and are willing to "interpret" the rules differently. What can you hot dogs out there recommend? We run a 3/8 dirt track and turn 6200 rpm. Our handling is pretty good, we just need more power. Thanks.

owracer
Dirt Maniac

Total posts: 103
posted February 22, 2001 09:56 PM
How much do you think your tech man will let pass? Also need more info on your engine and carb rules. cubic inch limit? Are limited to any hydralic cam or is it also a lift rule? Dome or flat top pistons? Deck clearance? What type of heads and intakes are you allowed?

RangeRover
Dirt Full Roller

Total posts: 37
posted February 27, 2001 09:01 PM
Thanks for the reply. Our tech man is very lenient; no car will be torn down unless one car is blatantly spanking everyone else. Our engines must have flat top pistons and no more than 360 ci. The hyd cam lift is limited to .500". Like I mentioned, decking and other internals will not be seen. We need to run a stock 4412 carb with non ported or angle-milled stock castings heads. We are allowed to run aluminum intake as long as it is a factory piece.

owracer
Dirt Maniac

Total posts: 103
posted February 27, 2001 11:08 PM
I hate to say it, but money buys speed. Seems the best head to run now is the vortec heads.Try to get engine rotating weight down as light as you can afford.Get your compression ratio up as high as possible.These heads and a zero deck height with flat top pistons will get you around 11.5. Is your cam lift measured at the valve or the cam lobe? I would talk with some of the cam company,s about a cam and talk to some professional carb builders about the carb. I have seen some people using the aluminum TBI intakes. If allowed, port match your intake and heads. I have even ran the deck height .005 out of the hole. This will add a little more compression. If allowed, I also like 6 inch rods.

awkwardjeff
Dirt Freak

Total posts: 218
posted February 28, 2001 08:33 AM
I would just like to say, that you should NEVER put the piston out of the bore.....
what you can in compression you loose in flame travel and ring seal........the pistons should be around .002-.006 down the bore.....ask any piston builder, Ross want their's .008 down the bore.
But go ahead and run the thin head gasket to get compression up. angle mill the heads does two things, First is to make the combustion chamber smaller the 2nd thing is it moves the valve away from the cylinder wall, unshrouding the valve face.
Also on the head take a die-grinder and open up the chamber at the intake valve closest to the wall. this will help let the air go around the whole valve not just part of the valve...........
My only point was not to let the piston out the bore. You can accomplish the same thing with better results by using a thin head gasket.......Jeff

RangeRover
Dirt Full Roller

Total posts: 37
posted February 28, 2001 09:10 PM
What exactly is done in the angle milling process guys? Is it detectable at a glance? One more question about the deck; what is the optimal quench tolerance to shoot for on a 355 with stock rods, turning from 5900 to 6300 rpm?

owracer
Dirt Maniac

Total posts: 103
posted February 28, 2001 11:03 PM
Most pistons will be within the range of the rings in the bore with the piston .005 out of the deck. A flat top pistons promotes the best flame travel, so I feel that the .005 out of the deck will not hurt. I ran this with no problems. Angle milling the heads takes more material off the exhaust side of the head than the intake side, giving you a smaller combustion chamber than just a flat milling of the head. Depends on how good of a tech man you have if he can detect this. I would say most likely not without cc.ing the heads. The smaller you can make the combustion chamber the better.

chomme
Dirt Full Roller

Total posts: 52
posted March 01, 2001 09:51 PM UIN: 1986763
I'll tell you what the guys run out here in CA where we race. In the Pure Stock division, which is basically hobby stock they run a 400 block, zero deck it, 400 cast crank (so it passes as stock), the new GM powdered metal (so they are factory produced) 6" rods (they are actually 5.94", but you can compensate in decking the block), two valve relief hypereutectic pistons (to raise compression), a cheater hydraulic cam, vortec heads, and the vortec marine intakes. They run really well.

In pro stock, our rules are..."Cast iron block and cast iron heads and production two barrel intake manifold." This is wide open...roller cams, belt drives, racing rods, you name it, all goes. We run a 383 small block...scat crank, 5.7" pm rods, 12.5:1 compression, fully ported 292 heads (that flow very well), solid cam (.542/.562, 252/260 @ .050), 1 3/4" headers, roller rockers, and for the intake...the brzezinski fully modified two barrel intake. Most guys won't advertise they run them, but I will say firsthand...just changing the intake made a world of difference. I was hesitatnt of spending $725 on an intake, but it was well worth it. For the carburetor, I run a built 4412, a 6425 (extensively modified...the 1 3/4" bores that is the 650 holley 2 barrel), or a c&s 890 cfm two barrel. For this year, I modified a TBI intake to fit the 890. That one requires 2" bores, and the TBI intake had enough meat for me to bore it out and hold the 890. The factory 2 bbl intakes would go thin on the edges and would need to be sleeved, so this one worked better. As to if my intake will perform as well as the brzezinski...only track time this season will tell. I also changed a few other things on the car, too.

All I can say is the fast guys are probably running the stuff. Another area is exhaust. Are you allowed to run headers in your class? Running an x in the pipes or anything of the sort? Brzezinski has some trick stuff if you have to run the stock exhaust components as well.

Their web site is www.castheads.com.

Also, I will say for carburetor spacers...if you run a stock intake with 2 bores (not opened up), don't use a open spacer. That cuts the power and hurts airflow...use a phenolic spacer like the brzezinski or moroso ones.

Hope this helps...

Chad

RangeRover
Dirt Full Roller

Total posts: 37
posted March 04, 2001 01:16 PM
Thanks, Chad, that's what I thought was going on. I guess I'm just gonna have to go with the flow and spend some more cash to be competitive. Our class, however, doesn't allow more than 360 ci and no stroking/destroking, so the tell-tale 400 block is out, but...how about an internally balanced 383? Tell me more about this "cheater" cam, Chad. Will this apply to a hydraulic or is running solid under cover part of the advantage? I've been hesitant to veer from the rule book, but it's terribly frustrating to get whooped every weekend, and nobody's getting broken down or protested anyway.
While on this subject, I know that the fine, outstanding individuals on this forum would never entertain the idea of CHEATING, but with your combined experiences, what cool tricks do you guys think would work? If you were forced, I mean.

racer17j
Dirt Maniac

Total posts: 165
posted March 08, 2001 02:38 AM UIN: 54865418
nobody has thought the gear are you running anything different than everybody else? another thing you might want to consider is changing rocker arm ratios. we run the same type engine rule and what we have forund works best is a cam dynamics cam and changing the rockers. if you would like email me and i'll give you the #'s on that maybe it will help racer17j@hotmail.com

[This message has been edited by racer17j (edited March 08, 2001).]

RangeRover
Dirt Full Roller

Total posts: 37
posted March 08, 2001 09:36 PM
I run 6.00 gears on a mildly banked 3/8 track. This let's me turn about a max 6200 RPM with my taller feature tires. Earlier, in the heat race, I will run a bit smaller tires in the rear to turn a little more RPM and take advantage of the tackier surface. Also, I run a little more stagger in the heat as opposed to almost straight up for the main. I guess a guy with a better motor wouldn't be afraid of running 6.20s but mine has got to last all season or I'm on the bench.
To answer an earlier question, I do run headers with 3" exhaust through a pair of two-chamber Flowmaster mufflers. It's a very straightforward system that I don't believe restricts too much. I love the way they sound, and I feel more comfortable in the car with the mufflers. I don't run an X or equilizer tube, because I built the exhaust myself; will an X make a noticable improvement?

Gannon
Dirt Newbie

Total posts: 1
posted March 08, 2001 11:08 PM
Sorry if this is difficult to read, but this is my first note on the bulletin board. I am replying to your question about using a cross-over pipe on your exhaust. A balance tube will act in the same way as increasing the collector length on open headers. What this does is increase your low-end torque, but it does not sacrifice top-end HP. You don't even have to make an "X", an "H" will work just as well, and you won't have to rebuild your entire exhaust.I've seen these balance pipes worth as much as 15 lb/ft of torque from idle to about 3500. It's cheap power and I highly recommend trying it.

chomme
Dirt Full Roller

Total posts: 52
posted March 12, 2001 07:46 PM UIN: 1986763
Hi there - in response to the cheater cams...depends upon the tracks cam rules. Do they have a lift limit, idle requirement, or ? Our tracks have a .450" lift limit, but if you run a hydraulic and like Rhodes Lifters or the Crane variable duration, you can run more and still pass a lift test at the valve. Not at the lifter, but they rarely check there. Also, remember...even with these low lifts, you can get a lot of duration out of cams and make good power.

As to the balance tube...I'm switching to an H type setup this year. Previously on the old car we ran 180's, but the way this car is built, it's too much work to switch it (cut out the interior and such). So I went with 1 3/4" schoenfelds and am putting in an H.

Good luck!

Chad

Limited5
Dirt Maniac

Total posts: 141
posted March 13, 2001 07:01 PM
Where do we start here? hmmmmmmmm acid porting? trick fuel? trick heads? It all depends how bad you want to win. I've heard bomber cars sound like latemodels before. Like the old saying goes "Show me a winner and I'll show you a cheater!" If your within the rules and they're running away from ya, their doin sumthin your not. 383 kits are cheap and fit in a 350 block, hmmmmmmmmmm.

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