Cramer Posted September 7, 2013 Report Share Posted September 7, 2013 Brad I was just joking when I said I was going to run nothing off the heads. I forgot to leave a gesture after that sentence. As for scavenging you are correct as it plays a role in expelling the gasses. And without it the amount of backpressure exceeds the rate at which the exhaust gases can be removed from the cylinder as the velocity has dropped and it takes pressure to move the next wave of expelled gasses. In Brads case, he winds his motor very high for being a truck and he can use the larger primary because it constantly has a hi rate of flow being spent out the exhaust. This might move his peak power up say to 6500rpm as this is where most people are not revving to. But the power has a small to no gain from 1k to 5k on his motor. But he won't see below 5k other than on a launch. Quote Link to comment Share on other sites More sharing options...
shadowsniper3006 Posted September 7, 2013 Report Share Posted September 7, 2013 Brad I was just joking when I said I was going to run nothing off the heads. I forgot to leave a gesture after that sentence. As for scavenging you are correct as it plays a role in expelling the gasses. And without it the amount of backpressure exceeds the rate at which the exhaust gases can be removed from the cylinder as the velocity has dropped and it takes pressure to move the next wave of expelled gasses. In Brads case, he winds his motor very high for being a truck and he can use the larger primary because it constantly has a hi rate of flow being spent out the exhaust. This might move his peak power up say to 6500rpm as this is where most people are not revving to. But the power has a small to no gain from 1k to 5k on his motor. But he won't see below 5k other than on a launch. Ohh I know bud. But your sarcasm actually made a great point that with essentially no back pressure from the header tubes you might loose hp but for a different reason. Truth be told, my motor peaks at exactly 7200 with the converter unlocked, which is how I race it. And that is with 1.750 header. I'm still of the opinion though a 1.875 on a stockish truck would be a good idea. I think Art should test this to. I do plan on testing a new header on my truck one of these days, but the results would be way to far off to use in any discussion like this. Sent from my SAMSUNG-SGH-I747 using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
poopnewton Posted September 7, 2013 Author Report Share Posted September 7, 2013 Most guys on pt.net seem to think 1 7/8 is the way to go on 6.0 and larger motors. For me as a 2wd guy if I ever get out my nightmarish hell of credit card debt and start to mod my truck I rather have more top end power than low end torque anyway. It's not like anyone who is 2wd Is ever gonna pull some great 60' on the street sitting on 20s, 22s, or 24s. Now if your awd and are one of those short stop light to stop light guys who is all about getting the best holeshot possible to beat stuff with less traction before they ever get a chance to catch back up while never going more than 10mph over the speed limit, than ok you might want to build strictly for low end torque IMO. Quote Link to comment Share on other sites More sharing options...
onebadmax Posted September 11, 2013 Report Share Posted September 11, 2013 I love it how a bunch of people in this thread, who don't have 1-7/8 headers, say they lose power on a stock truck.... SMDH. Quote Link to comment Share on other sites More sharing options...
skolman91 Posted September 13, 2013 Report Share Posted September 13, 2013 Ohh I know bud. But your sarcasm actually made a great point that with essentially no back pressure from the header tubes you might loose hp but for a different reason. Truth be told, my motor peaks at exactly 7200 with the converter unlocked, which is how I race it. And that is with 1.750 header. I'm still of the opinion though a 1.875 on a stockish truck would be a good idea. I think Art should test this to. I do plan on testing a new header on my truck one of these days, but the results would be way to far off to use in any discussion like this. Sent from my SAMSUNG-SGH-I747 using Tapatalk 2 If you run it that high with that big of a converter, you should invest in some of those l92 heads you love so much and some bigger headers and id be willing to bet you would have 11's in the bag easy... but what do i know right... Quote Link to comment Share on other sites More sharing options...
JC03SS Posted September 13, 2013 Report Share Posted September 13, 2013 He already has some o the baddest trickflow heads you can have if I'm not mistaken. Quote Link to comment Share on other sites More sharing options...
BLNAWAY Posted September 13, 2013 Report Share Posted September 13, 2013 He already has some o the baddest trickflow heads you can have if I'm not mistaken.that he does If you run it that high with that big of a converter, you should invest in some of those l92 heads you love so much and some bigger headers and id be willing to bet you would have 11's in the bag easy... but what do i know right... trick flow over stock L92 any day if you got the $$ to spend......but on a budget build yes these head would be good Quote Link to comment Share on other sites More sharing options...
shadowsniper3006 Posted September 13, 2013 Report Share Posted September 13, 2013 (edited) If you run it that high with that big of a converter, you should invest in some of those l92 heads you love so much and some bigger headers and id be willing to bet you would have 11's in the bag easy... but what do i know right... I agree with you completely....... What would you know..... Sent from my GT-N8013 using Tapatalk 2 Edited September 13, 2013 by shadowsniper3006 (see edit history) Quote Link to comment Share on other sites More sharing options...
poopnewton Posted September 13, 2013 Author Report Share Posted September 13, 2013 If you run it that high with that big of a converter, you should invest in some of those l92 heads you love so much and some bigger headers and id be willing to bet you would have 11's in the bag easy... but what do i know right... Hey I thought I was the l92/ls3 head fan boy in this thread damnit. Quote Link to comment Share on other sites More sharing options...
skolman91 Posted September 14, 2013 Report Share Posted September 14, 2013 that he does trick flow over stock L92 any day if you got the $$ to spend......but on a budget build yes these head would be good I never said stock l92s, trick flows are some good heads and better than stock 92s depending on which ones. But gotta pay to play and go fast, some nice l92s arent cheap.. I agree with you completely....... What would you know..... Sent from my GT-N8013 using Tapatalk 2 LOL, you have no idea.. Okay back on topic no more chit chatting about people and their "fast" trucks. WHO WANTS TO BE THE FIRST TO BUY THESE AND SEE HOW WELL THEY FIT on a awd sss? Im curious and broke or i would, if i had to guess it would take quite a bit of beating on one of the down tubes to the extent it might not even be worth with the cheap stuff. But then again guy over on pt net said they fit just like the reg 3/4" pacesetters did, but that was a 2wd of course.. Quote Link to comment Share on other sites More sharing options...
chpspecial Posted September 14, 2013 Report Share Posted September 14, 2013 So just to keep the discussion going. What's the deal with top fuel dragsters and the big boys in nhra. Most have straight primaries with no collectors and have anywhere from 1600 to 8k HP. They might do it once, but they have no scavenging effect. And if it's scavenging that is best, why not run 180° headers to have a true balanced exhaust stream. Sent from my HTC6500LVW using Tapatalk 4 Quote Link to comment Share on other sites More sharing options...
shadowsniper3006 Posted September 15, 2013 Report Share Posted September 15, 2013 (edited) Thats a hell of a point reynaldo, but are you playing Devils advocate or do you think scavenging is over rated? If the cam has the proper overlap im thinking our motor will always benift from scavenging(and I guess provided the overlap doesn't bleed the motor dry of compression, so dcr being about 8.9), just by pulling the mixture through its intake valve. I believe this can be proved or seen by having to adjust the injector end timing and watching your wideband get richer by moving up the end point(injecting sooner), and putting less raw gas in the header primary on the top or overlap of the intake stroke. ??? Did I say that right? Sent from my GT-N8013 using Tapatalk 2 Edited September 15, 2013 by shadowsniper3006 (see edit history) Quote Link to comment Share on other sites More sharing options...
Cramer Posted September 15, 2013 Report Share Posted September 15, 2013 I know that a lot of the fuel cars run cams ground with a huge offset due to the fact that the crank can twist to around 20* at top end. This helps keep the cam phased with the rest of the motor and not smack the valves through the pistons. I believe the nitro cars run a afr of around 1.7:1 which accounts for all the unburnt fuel that doesn't get ignited and spent out the exhaust. The plugs are toast by the end of the run usually and most of the ignition of the fuel is from heat in the cylinders and the dieseling effect. This is some of the reasons why a fuel or high HP nhra car run with no collector. Plus the fact that they can run around 60lbs of boost and are wot the whole run. Sent from my Motorola RAZR MAXX using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
chpspecial Posted September 15, 2013 Report Share Posted September 15, 2013 I was just playing devils advocate. I do believe in scavenging Sent from my HTC6500LVW using Tapatalk 4 Quote Link to comment Share on other sites More sharing options...
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