Is there a limit to head flow

jeffmckc · Post by **jeffmckc** » Sat Jan 19, 2008 3:35 pm

The Ports where designed by Curtis I have all the trust in the world that they are what it needed for what I sent him. I dont have the build sheet on them he is going to send it to me.

I question your chassis dyno#s 596rwhp should be a lot faster than you are going, mine runs 103 in the 1/8 @6.54 with a 4.30 gear I will say I am not a fan of the chassis dynos to many variables to try to compare a car to any other cars like you are doing. I have talked to Jay on the phone before about my 420, and I will not group him in with the trust me guys but he also will not give a idea of the cam he is selling you, so I wont be going to him for this reason. I have bought 4 of these cams I will be spending my money with someone, but I will make sure its in the area I need this time.

Jason are you the one who keeps PMing me about the heads? You said Jays cam only gave you 1 mph then.

Jason G · Post by **Jason G** » Sat Jan 19, 2008 3:47 pm

Jeff,

I have not PM'd you.

I agree you cannot compare chassis dyno number, much like flow numbers, and engine dyno numbers. That being said, on the same dyno, my car picked up ~27 RWHP.

As far as my car should be a bunch faster for the power. I agree. The ET doesn't match the MPH because of the converter and gear. Also keep in mind, my car weighs 3650 lbs. Not 3050 lbs.

Jason G.

jeffmckc · Post by **jeffmckc** » Sat Jan 19, 2008 3:51 pm

Sorry then, wrong guy he had 18Xs also and was pricing porting from RFD not many of us using them.

I know the weight is a big factor, thats why mine is light, and 27 more on the same dyno is a big change.

Jason G · Post by **Jason G** » Sat Jan 19, 2008 4:00 pm

Jeff,

You are right that there aren't that many of us using the 18X heads, probably for good reason.

I won't be using the 18X's much longer. When I'm satisfied the car is hooking consistently and leaving better, I plan on switching to a set of Dart 18 degree castings that I plan to have Curtis to work his magic on.

No more peak power at 6500 RPM

Good luck with your car and keep us posted.

Jason G.

jeffmckc · Post by **jeffmckc** » Sat Jan 19, 2008 4:04 pm

You should buy and have him finish the 12-13s that are on his specials page I own, for your large motor they may work fine.

Ed-vancedEngines · Post by **Ed-vancedEngines** » Sat Jan 19, 2008 4:25 pm

I have talked to Jay on the phone before about my 420, and I will not group him in with the trust me guys but he also will not give a idea of the cam he is selling you, so I wont be going to him for this reason

Jay got maligned and trashed by a hater that got several of his buddies to come on a board and join in on the hating. Hi sbusiness was trashed and his reputation was trashed by a select few who all were a cliq.

That was unfair to him and as much as I have seen posted by guys loving his stuff and guys who he has helped and worked with and seeing how far out of his way he would go to try to help a customer or correct a wrong, I would have no problem trusting him to do what he says. He and I do not agree about what to do with a cam on extreme nitrous applications and that is fine. Most other guys don't agree with me either.

About Chassis dyno comparisons. You can't.

Ed

ADR · Post by **ADR** » Sat Jan 19, 2008 5:05 pm

38 degrees of timing ?

jeffmckc · Post by **jeffmckc** » Sat Jan 19, 2008 5:14 pm

ED you have seen me defend Jay before, he took a lot of time with me one night as a favor to Patrick at prosystems, but I could not give him all the info he needed at the time to make a shaft for me, or I would have got one of his last time. I just ranout of time for my race and had to make a move. Now I am just soured on the trust me stuff, I am not asking for all specs ahead but close so I dont buy a 114* degree cam again.

I posted the 38* on purpose this is a huge chamber at 68cc and 11.3 Total if I back it off it slows dramaticly on MPH and 60 foot both. As stated I am not a guy who claims to know all when it comes to camshaft vodoo, but I think the chamber and camshaft may have some to do about that.

hsutton · Post by **hsutton** » Sat Jan 19, 2008 5:22 pm

Hi all, I find the main variable on a chassis dyno is the torque converter and how much slippage any particular converter has. Jesse Nelson, who just finished second in the "Dynomax" dyno challenge, changed his converter to one that would better hold the power he had and gained 160 RWHP. For that reason alone just using this type of machine to tell you whether you are gaining or losing power is the right way to do a test. Even after you know how much power you have though, you will still only have a vague idea of what a car will run. I would trust Curtis, Big Joe and Ed to steer you in the right direction. None of these guys will sell you anything you don't need, and all three have mountains of experience. The right converter can produce big gains. A 400 Turbo has lots of weight turning in low gear and will generally go quicker if you shift out of low a little sooner. If it's a T-400 you might talk to Coan about their lightweight 400XLT or the 350XLT. John Wilson has a Coan 350XLT with a reduced first gear (2.34 low) that only weighes 109 lbs. and can be had with a Sprag delete which is 4 lbs. lighter vs. a stock 350's weight of 119 lbs. It has lots of billet parts. The tranny has been dead reliable so far.

Jason G · Post by **Jason G** » Sat Jan 19, 2008 6:12 pm

On the chassis dyno crap.

I only brought it up for a comparison on my car alone, which happens to use the same head casting as Jeff (the original poster). I dynoed before and after the cam swap. No other changes. Not even valvesprings (valvesprings were chosen by Jay - I installed them on the old cam first to eliminate another variable). I wasn't comparing to anyone else's car. As Harold S. mentioned, comparisons on the same car are the only thing the chassis dyno is really good for.

I was in no way meaning to suggest or imply anything else. I believe the ET/MPH also suggest a noticable jump in power in the example I gave.

The point. Camshaft CAN make a significant difference.

As far as Jay's cams go, I have seen enough to put my trust in him and I will continue to do so. His stuff works. To each their own though.

Jason G.

jeffmckc · Post by **jeffmckc** » Sat Jan 19, 2008 6:23 pm

I understand your post Jason, and will be using the test I did as only a baseline for what I am doing like yours.

My car can hook the 2.45 and needs the gear because of the 4.30 in the back to get it moving, but most of the time I am waiting for the front end to come back down to shift to second. Its a Drag Radial car and it transfers to hook.

Thanks Jeff

hsutton · Post by **hsutton** » Sat Jan 19, 2008 10:32 pm

Jeffmckc, The Coan superlight transmission is rather pricey but a drop of rotating weight of 10 lbs. is substantial enough to show a tenth or more in E.T. gains. I saw Gapp & Roush take all the fluid out of their Lenco one time to win a final when they raced the "Tijuana Taxi". It burned up the Lenco but picked up a tenth and they won the race against Jenkins' Vega. Rebuilding the transmission cost about $2000-$3000 dollars but they won tens of thousands. I think you can get many different first gear ratios in either the T-350XLT or the T-400XLT transmission, the info. is on their website about both. There is a new converter coming from Neal Chance that looks neat but probably costs a fortune too.

Troy Patterson · Post by **Troy Patterson** » Sat Jan 19, 2008 11:23 pm

jeffmckc wrote:ED you have seen me defend Jay before, he took a lot of time with me one night as a favor to Patrick at prosystems, but I could not give him all the info he needed at the time to make a shaft for me, or I would have got one of his last time. I just ranout of time for my race and had to make a move. Now I am just soured on the trust me stuff, I am not asking for all specs ahead but close so I dont buy a 114* degree cam again.

114* camshafts are hot stuff! Your power band is flat because you are running a mildly modified stock Holley Pro Systems carb.

You could make mountains more torque with a seriously built carb, not one where you're paying for the price of popularity.

Tight lca's do what????? They use inertial and reflective wave, resonant frequency (call it what you like) energy to aid in scavenging the cylinder and boosting the carb signal via drawing on the intake port during overlap to increase cylinder fill.

Run a good carb and fuel curve and you don't need to compromise valve events.

Running excessively large diameter primaries and collectors can also result in a reduction in the exhaust systems ability to effectively scavenge the cylinder. Most guys run more header / collector than necessary - they often install bigger, more radical camshafts in an attempt to realize the missing power. This is where people build 600 hp engines to realize 500.

If you guys are talking about that Jay cam guy - what a jerk! Has he reached puberty yet? I contributed to that miserable sbford tech forum until I couldn't stand the childish mentality making me sorry I contributed my time and knowledge to them. They (Jay and buddies) targeted me because I didn't agree with all their ideas. I guess I was a threat to their fragile hold on their claim of authority on the subject. My two cents worth.

Ed, you're a nice guy for sticking up for underdogs. Perhaps you've seen another side of him.

Troy Patterson TMPCarbs.net TMP Carbs

jeffmckc · Post by **jeffmckc** » Sun Jan 20, 2008 3:09 pm

114* are hot stuff from what I have seen on 14 to 1 motors or serious spray cars, but not on low compression N/A cars. Am I wrong on this line of thinking? To much duration and to big a exhaust lobe make for such a big lobe center to keep the overlap down.

Troy Patterson · Post by **Troy Patterson** » Sun Jan 20, 2008 4:06 pm

jeffmckc wrote:114* are hot stuff from what I have seen on 14 to 1 motors or serious spray cars, but not on low compression N/A cars. Am I wrong on this line of thinking? To much duration and to big a exhaust lobe make for such a big lobe center to keep the overlap down.

I'll admit I'm unconventional in the application of wide lobe center angles because of my believe in the fact that what is really providing the benefit, more than any other factor is increased signal strength at the carb, not increased cylinder filling and so forth - it's improved combustion efficiency resulting from a better air / fuel ratio that ultimately delivers the torque / horsepower increase as a result of the use of exhaust energy during overlap.

I only say this because I've widened lca's and replaced carbs an realized the same, similar or greater performance gains / characteristics attributed to tight lca's while benefiting from the broader power band and characteristics of the wide lca. I'll admit I haven't done this on a wide variety of applications - but I feel pretty confident it's generally applicable.

Troy Patterson TMPCarbs.net TMP Carbs