408 help quick
408 help quick ok guys got done doing a dyno on the car today and got some pretty sad numbers. heres what i got.
408
6.0 iron block
4.030 -12cc dish mahle pistons
6.125 compstar rods
4.00 inch eagle crank
rollmaster double roller
tsp mini stick (235/240 with .603 .609 on a 112 lsa)
slp long tubes with after market cat-back
home ported 99 camaro ss heads(casting 853) with stock valves
ls6 ported oil pump
mcloed street twin
d&d t56
moser 12 bolt with 4.10s
now heres the sad part. first pull of the day was with absolutley no tuning. except to make it run ok because a friend of mine has efi live and hes doing the tuning for us
we got 385.6hp and 390.8tq. with a 12.9 air fuel and 31 degrees at wot
then we tryed backing off the timing to 26 degrees and got
388.5hp and 410.3tq
then we tryed 18 degees and got
367.1hp and 400.8tq
all these pulls were with a good 12.8 air fuel. so we brought the timing back up where we made the most power and took of the dual cut-outs and finally made 400.6hp and 436.4tq. now heres the weird part. everything was falling on the dyno chart after 5500 rpms. the power dropped and the torqued dropped. so what are your thoughts guys. we were thinking to little of cam and maybe not the compression that we thought we had. with those pistons and stock heads i was told i would get 10.5.1 compression. sorry its so long guys but i really need your help. im also gonna spray a 200 shot to it. i was thinking of a cam in the 260 range at .50 with about .630 lift.
again sorry its so long but i need help to figure this thing out
thanks Jason
408
6.0 iron block
4.030 -12cc dish mahle pistons
6.125 compstar rods
4.00 inch eagle crank
rollmaster double roller
tsp mini stick (235/240 with .603 .609 on a 112 lsa)
slp long tubes with after market cat-back
home ported 99 camaro ss heads(casting 853) with stock valves
ls6 ported oil pump
mcloed street twin
d&d t56
moser 12 bolt with 4.10s
now heres the sad part. first pull of the day was with absolutley no tuning. except to make it run ok because a friend of mine has efi live and hes doing the tuning for us
we got 385.6hp and 390.8tq. with a 12.9 air fuel and 31 degrees at wot
then we tryed backing off the timing to 26 degrees and got
388.5hp and 410.3tq
then we tryed 18 degees and got
367.1hp and 400.8tq
all these pulls were with a good 12.8 air fuel. so we brought the timing back up where we made the most power and took of the dual cut-outs and finally made 400.6hp and 436.4tq. now heres the weird part. everything was falling on the dyno chart after 5500 rpms. the power dropped and the torqued dropped. so what are your thoughts guys. we were thinking to little of cam and maybe not the compression that we thought we had. with those pistons and stock heads i was told i would get 10.5.1 compression. sorry its so long guys but i really need your help. im also gonna spray a 200 shot to it. i was thinking of a cam in the 260 range at .50 with about .630 lift.
again sorry its so long but i need help to figure this thing out
thanks Jason
probably your biggest two concerns are your heads and cam.. try after market heads such as afr's or etp or if you cant afford those get someone really good to port your stock ones, change the valves and change your cam. Also I have 408 11:1 and i wish i could of gone with higher compression maybe you should think about going with higher compression then what you have.. those three things will for sure get you more power, but i think the main problem is your heads.
Originally Posted by VIPER EATER
i was thinking of a cam in the 260 range at .50 with about .630 lift.
again sorry its so long but i need help to figure this thing out
thanks Jason
again sorry its so long but i need help to figure this thing out
thanks Jason
If I had a dollar for everytime I've seen someone try to "over cam" a car to make up for poor heads I could have built my 408 for free (notice I didnt say become a millionaire
)Seriously what kind of numbers were you expecting? 475? 500? 525?
If you REALLY want to eat vipers "viper eater"....
You need some GOOD heads (TEA's, ETP's,AFR's) then you give an Ed curtis a call (EDC on here) and have him custom make you a cam to fit YOUR NEEDS, then if in fact your after one of those 550+ numbers, you add a ported 90/90 setup on it and some 1 7/8 headers and THEN you post back up and tell us how HAPPY you are with your new numbers
OR..............
If money is an issue....pay to get it professionaly tuned, then buy a wet kit for it a spray the hell out of it (assuming you have the proper fuel system of course)
either way, good luck and keep us posted.
Originally Posted by dame
If I had a dollar for everytime I've seen someone try to "over cam" a car to make up for poor heads I could have built my 408 for free (notice I didnt say become a millionaire )
Seriously what kind of numbers were you expecting? 475? 500? 525?
If you REALLY want to eat vipers "viper eater"....
You need some GOOD heads (TEA's, ETP's,AFR's) then you give an Ed curtis a call (EDC on here) and have him custom make you a cam to fit YOUR NEEDS, then if in fact your after one of those 550+ numbers, you add a ported 90/90 setup on it and some 1 7/8 headers and THEN you post back up and tell us how HAPPY you are with your new numbers
OR..............
If money is an issue....pay to get it professionaly tuned, then buy a wet kit for it a spray the hell out of it (assuming you have the proper fuel system of course)
either way, good luck and keep us posted.
)Seriously what kind of numbers were you expecting? 475? 500? 525?
If you REALLY want to eat vipers "viper eater"....
You need some GOOD heads (TEA's, ETP's,AFR's) then you give an Ed curtis a call (EDC on here) and have him custom make you a cam to fit YOUR NEEDS, then if in fact your after one of those 550+ numbers, you add a ported 90/90 setup on it and some 1 7/8 headers and THEN you post back up and tell us how HAPPY you are with your new numbers
OR..............
If money is an issue....pay to get it professionaly tuned, then buy a wet kit for it a spray the hell out of it (assuming you have the proper fuel system of course)
either way, good luck and keep us posted.
Thanks Jason
Originally Posted by offaxis
Did ya get any flow numbers off your homeported heads before they were instLLed?
A bad port job can make them worse than stock. Thats Just a thought though
A bad port job can make them worse than stock. Thats Just a thought though
Thanks Jason
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Originally Posted by VIPER EATER
the other set of heads that im gonna port will be done right. (bigger valves, flow tested) things of that sort
Thanks Jason
Thanks Jason
Have you ported heads before
Or did you mean the next set of heads you have ported will have larger valves , etc, etc? yeah i ported a set of LT-1 heads before for my 94 Z28 that used to have. and the lifters that im running are just clevite replacments. and yes the stock 241 casting that i have that came off the camaro to begin with will have bigger valves
Thanks Jason
also i cant post the graph cause i dont have a scanner and i dont know wnybody that has one
Thanks Jason
also i cant post the graph cause i dont have a scanner and i dont know wnybody that has one
take a pic with a digital camera or camera phone. could be wrong cam timing, lifter preload issues, lack sufficient heads and intake, or another mechanical problem. also, what valve springs are you running?
im running the prc platnium kit. and as soon as the guy that dynoed the car gets another ink cartrige in his printer ill post it up. ill go out there tomorrow and get it
Thanks Jason
Thanks Jason
Staging Lane
Joined: Dec 2005
Posts: 75
Likes: 0
Most likely you are choking it with your heads etc...
What is your intake system and what size injectors...?
Also is the power droping slowly after 5500 or is it a sharp drop...?
If it's a sharp drop you may be running into valve float.
What is your intake system and what size injectors...?
Also is the power droping slowly after 5500 or is it a sharp drop...?
If it's a sharp drop you may be running into valve float.
1.) Your heads are holding you back. Even if your port work is good, the stock valve size is way too small for the 408's bore.
2.) SLP headers MAY be holding you back. You probably would see better results with Kook's or QTP's.
3.) Which aftermarket catback are you running? What size is your y pipe? For best power, I would recommend 3" true duals with an X pipe.
4.) I might go slightly bigger on the cam. I wouldn't go to a 260 duration cam unless you don't care at all about drivability- and a cam that big may not be ideal for power production, either. I also would recommend contacting Ed Curtis to help you choose a cam.
5.) What is your intake setup? LS1 intake? LS6 intake? You need at least an LS6 intake with a good ported stock TB. For a good boost in power, get a ported FAST 90mm intake and a Nick Williams TB.
6.) Are you sure you are getting sufficient fuel? What size injectors? Fuel pump?
7.) You could go a little leaner on the tune to squeeze a few more HP out of the current setup. Try 13.3-13.5:1, but be on the lookout for KR.
Good luck!
2.) SLP headers MAY be holding you back. You probably would see better results with Kook's or QTP's.
3.) Which aftermarket catback are you running? What size is your y pipe? For best power, I would recommend 3" true duals with an X pipe.
4.) I might go slightly bigger on the cam. I wouldn't go to a 260 duration cam unless you don't care at all about drivability- and a cam that big may not be ideal for power production, either. I also would recommend contacting Ed Curtis to help you choose a cam.
5.) What is your intake setup? LS1 intake? LS6 intake? You need at least an LS6 intake with a good ported stock TB. For a good boost in power, get a ported FAST 90mm intake and a Nick Williams TB.
6.) Are you sure you are getting sufficient fuel? What size injectors? Fuel pump?
7.) You could go a little leaner on the tune to squeeze a few more HP out of the current setup. Try 13.3-13.5:1, but be on the lookout for KR.
Good luck!
Originally Posted by BADSS
Try 13.3-13.5:1, but be on the lookout for KR.
