Very Dissapointed with dyno results today...
05-07-2006, 12:05 PM
#21
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Originally Posted by Abdullah
maybe the pushrods are off, you have to get the stock length 7.400", just an idea to check.
05-07-2006, 12:43 PM
#22
Originally Posted by joshp14
I had 7.400" for when I had the cam only setup. Now that I have AFR heads milled .024", and .040" cometic's, I bought a pushrod length checker and measured it that way. I then added my lifter preload to get a total pushrod length of 7.325". I made 100% sure I was on the base lobe of the cam when I measured it and I dont even know how many times I double checked it...I even had my father standing there next to me to have two brains there instead of just mine.
05-07-2006, 01:57 PM
#23
also be sure you checked the PR length on a valve that was not opening, the slightest ramping up of the cam can throw your numbers off big time. I would think you should be running 7.425" PR's depending on recommended preload for the lifters. That could mean 20-30 HP you are down, not the full total but if you are only missing 30 hp instead of 60, that could mean the tune can be partly to blame if it is off as well, as 20-30 hp in a tune wouldnt be much to gain if its not dialed in.
05-07-2006, 04:38 PM
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Originally Posted by WS6FirebirdTA00
also be sure you checked the PR length on a valve that was not opening, the slightest ramping up of the cam can throw your numbers off big time. I would think you should be running 7.425" PR's depending on recommended preload for the lifters. That could mean 20-30 HP you are down, not the full total but if you are only missing 30 hp instead of 60, that could mean the tune can be partly to blame if it is off as well, as 20-30 hp in a tune wouldnt be much to gain if its not dialed in.
Also, when I installed these heads, I didnt shim the springs, is this necessarily a bad thing?
Last edited by joshp14; 05-07-2006 at 05:04 PM.
05-07-2006, 06:59 PM
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Originally Posted by WS6FirebirdTA00
ok, thats cool. I was just wondering because the size I use minus your milling and what not would put you at a 7.425 depending on the lifter preload. Now did a shop tell you that or did you get the information directly from the manuf?
05-07-2006, 07:09 PM
#27
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Originally Posted by joshp14
I can understand to use longer pushrods when changing out just the cam, but I put shaved heads on as well as thinner head gaskets. I milled the heads .024" and used .040" Cometic's which is .014" thinner than stock....so total is .038" thinner than stock gaskets and stock heads. Plus the lifters I am using only need a .030-.040 preload. When I measured the length I made DAMN sure it was on the base circle and the valve wasnt opening.
Also, when I installed these heads, I didnt shim the springs, is this necessarily a bad thing?
Also, when I installed these heads, I didnt shim the springs, is this necessarily a bad thing?
It sounds as if your measurements are close with the different lifters.
05-07-2006, 07:26 PM
#28
Have you called or e-mailed Tony Mamo at AFR?
He is usually very helpful.
I bet there is at least 10-15 RWHP more in it through more tuning, but that would still put you lower on power than you should be. You really need it tuned in person- a mail-order tune just doesn't cut it.
I'm sure Tony will tell you that the AFR's can tolerate more timing and a leaner A/F ratio than stock ported heads due to the more efficient combustion chamber design of the AFR heads. I bet you can lean it out some and add some timing and gain power.
Unless your injectors are over 100% duty cycle, don't waste your money on injectors.
He is usually very helpful.
I bet there is at least 10-15 RWHP more in it through more tuning, but that would still put you lower on power than you should be. You really need it tuned in person- a mail-order tune just doesn't cut it.
I'm sure Tony will tell you that the AFR's can tolerate more timing and a leaner A/F ratio than stock ported heads due to the more efficient combustion chamber design of the AFR heads. I bet you can lean it out some and add some timing and gain power.
Unless your injectors are over 100% duty cycle, don't waste your money on injectors.
05-07-2006, 07:48 PM
#29
Originally Posted by Ksett
FYI. My mechanic measured and we used 7.375 pushrods. I have the F13 with .036 milled off of my AFR 205's with a .045 Cometic, using stock lifters.
It sounds as if your measurements are close with the different lifters.
It sounds as if your measurements are close with the different lifters.
05-07-2006, 07:48 PM
#30
Originally Posted by joshp14
I called Lunati direct and they said .030-.040. I also called other speed shops like TR and TSP. I ended up using the .050" which was closest to the Lunati spec.
05-07-2006, 07:51 PM
#31
I would like to know some more info on the lifters, do you have an email? If the pushrods are too long you can also lose compression. Do a compression test on the car. Since our cams are the same you should see a higher ratio based on your CR increase over mine. Do you have a compression tester?
05-07-2006, 08:21 PM
#34
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Originally Posted by BADSS
.
Unless your injectors are over 100% duty cycle, don't waste your money on injectors.
Unless your injectors are over 100% duty cycle, don't waste your money on injectors.
First off, I would strongly disagree with the above statement.... the ideal place to run an injector (especially with sequential injection and stock fuel rails) is 70% DC or below. It has to do with injector timing issues and the hydraulics of the fuel rail with regard to cyinder distribution. I have NEVER seen an LS1 with a cam and heads that didn't need to upgrade the inj's.
Second, stay away from the BP fuel.... at least in our area. I have seen countless problems with their premium fuel in performance engines due to detonation issues. It doesn't seem to be a problem with any other brand of fuel that I have used, and it may not be a problem in other parts of the country, but up here, the regional blend they use has been nothing but problems.
Third, you may be having a problem with your choice of head gaskets. With GM setting the deck clearance for an LS1 to about .005-.010" above the deck, a .040" gasket will NOT provide adequate piston to head clearance. I have seen countless engines with .040" piston/head run the pistons into the head... especially engines with loose skirt clearances or short piston designs such as in an LS1. The gain in quench simply doesn't make any more power and having parts running into each will trip the knck sensor falsely, kill the rod bearigs, hurt HP and possibly even worse. I now run .045-.050" piston to head clearance on all my engines because of this problem. Even the piston mfg's have gone away from the old reverse dome design to a spherical dish (which has no quench pad) in competition motors and improved HP due to better flame travel.
I would agree to check for WOT as that could cause the problem you are describing. I would say the other possibilities llisted in this thread are unlikely to cause the serious lack of power you are experiencing.
Brian
HiTech Motorsport
05-07-2006, 08:37 PM
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Originally Posted by HTMtrSprt
Josh,
First off, I would strongly disagree with the above statement.... the ideal place to run an injector (especially with sequential injection and stock fuel rails) is 70% DC or below. It has to do with injector timing issues and the hydraulics of the fuel rail with regard to cyinder distribution. I have NEVER seen an LS1 with a cam and heads that didn't need to upgrade the inj's.
Second, stay away from the BP fuel.... at least in our area. I have seen countless problems with their premium fuel in performance engines due to detonation issues. It doesn't seem to be a problem with any other brand of fuel that I have used, and it may not be a problem in other parts of the country, but up here, the regional blend they use has been nothing but problems.
Third, you may be having a problem with your choice of head gaskets. With GM setting the deck clearance for an LS1 to about .005-.010" above the deck, a .040" gasket will NOT provide adequate piston to head clearance. I have seen countless engines with .040" piston/head run the pistons into the head... especially engines with loose skirt clearances or short piston designs such as in an LS1. The gain in quench simply doesn't make any more power and having parts running into each will trip the knck sensor falsely, kill the rod bearigs, hurt HP and possibly even worse. I now run .045-.050" piston to head clearance on all my engines because of this problem. Even the piston mfg's have gone away from the old reverse dome design to a spherical dish (which has no quench pad) in competition motors and improved HP due to better flame travel.
I would agree to check for WOT as that could cause the problem you are describing. I would say the other possibilities llisted in this thread are unlikely to cause the serious lack of power you are experiencing.
Brian
HiTech Motorsport
First off, I would strongly disagree with the above statement.... the ideal place to run an injector (especially with sequential injection and stock fuel rails) is 70% DC or below. It has to do with injector timing issues and the hydraulics of the fuel rail with regard to cyinder distribution. I have NEVER seen an LS1 with a cam and heads that didn't need to upgrade the inj's.
Second, stay away from the BP fuel.... at least in our area. I have seen countless problems with their premium fuel in performance engines due to detonation issues. It doesn't seem to be a problem with any other brand of fuel that I have used, and it may not be a problem in other parts of the country, but up here, the regional blend they use has been nothing but problems.
Third, you may be having a problem with your choice of head gaskets. With GM setting the deck clearance for an LS1 to about .005-.010" above the deck, a .040" gasket will NOT provide adequate piston to head clearance. I have seen countless engines with .040" piston/head run the pistons into the head... especially engines with loose skirt clearances or short piston designs such as in an LS1. The gain in quench simply doesn't make any more power and having parts running into each will trip the knck sensor falsely, kill the rod bearigs, hurt HP and possibly even worse. I now run .045-.050" piston to head clearance on all my engines because of this problem. Even the piston mfg's have gone away from the old reverse dome design to a spherical dish (which has no quench pad) in competition motors and improved HP due to better flame travel.
I would agree to check for WOT as that could cause the problem you are describing. I would say the other possibilities llisted in this thread are unlikely to cause the serious lack of power you are experiencing.
Brian
HiTech Motorsport
I had received countless opinions from members here on LS1tech and also from vendors such as AFR and not one said that running a .040" gasket would cause any problems. I havent had any problems with detonation that I know of on the BP gas...I'll look around for some injectors and prolly buy a set as well. Any other reasoning behind my lack of power? Do you really think that the gas and quench is causing my loss?
05-07-2006, 08:46 PM
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Josh,
No, I don't think the quench or the gas is causing the LARGE lack of HP.... unless the PCM is showing serious KR. Just thought I would pass the info on as they CAN cause problems you will want to steer clear of. The lack of power could be caused by not getting WOT as another person said, not to mention many other possibilities, but without having the car here, it is almost impossible to speculate what those causes may be.
Brian
HiTech Motorsport
No, I don't think the quench or the gas is causing the LARGE lack of HP.... unless the PCM is showing serious KR. Just thought I would pass the info on as they CAN cause problems you will want to steer clear of. The lack of power could be caused by not getting WOT as another person said, not to mention many other possibilities, but without having the car here, it is almost impossible to speculate what those causes may be.
Brian
HiTech Motorsport
05-07-2006, 08:53 PM
#38
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Originally Posted by Patrick G
Did you ever check to see if your TB is opening up 100%?
05-07-2006, 09:03 PM
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Originally Posted by WS6FirebirdTA00
timing can make a huge difference but what makes me curious is the fact that he dynoed low cam only
05-07-2006, 09:08 PM
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Originally Posted by cantdrv65
3 degrees timing is NOT going to make more than a few hp difference if ANY. My car makes 2 more hp going from 23 degrees timing to 28. Its a wash. Something is mechanically wrong here. 7.32 sounds awfully short for the pushrods...