Lost 100 HP over a Cam swap - HELP!!
05-12-2008, 06:06 PM
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Lost 100 HP over a Cam swap - HELP!! I recently had a solid roller setup on a 396 LT4 - i had a lifter go bad which caused the cam to go bad. when replacing, i decided to go to a hydraulic roller setup (try to make it more streetable??). my current setup is as follows:
582/579 .242 duration comp cam
rocker arms are 1.6
hooker long tube headers
electric water pump
stage 3 lt4 heads
random tech catconverters
b&b tri-flo exhaust w/qtp electric cutouts
58mm holley throttle body
4.10 gears
i replaced valve springs, pushrods, spark plugs, spark plug wires, all gaskets, had a custom tune put on it - my solid roller setup had a 610 lift with the same duration. i knew i might lose some power, but i am down from 456 to 362 hp.
any thoughts or suggestions will be greatly appreciated.
582/579 .242 duration comp cam
rocker arms are 1.6
hooker long tube headers
electric water pump
stage 3 lt4 heads
random tech catconverters
b&b tri-flo exhaust w/qtp electric cutouts
58mm holley throttle body
4.10 gears
i replaced valve springs, pushrods, spark plugs, spark plug wires, all gaskets, had a custom tune put on it - my solid roller setup had a 610 lift with the same duration. i knew i might lose some power, but i am down from 456 to 362 hp.
any thoughts or suggestions will be greatly appreciated.
Last edited by spdracr713; 05-19-2008 at 12:36 PM. Reason: more info
05-12-2008, 07:28 PM
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What do you mean by that? If you mean more driveable I can't understand why a SR cam profile like what you're running would have drivability issues? Especially on a stroker?
No idea on the power loss. My answer to anything like this is to get a leak down and check your valve adjustment.
No idea on the power loss. My answer to anything like this is to get a leak down and check your valve adjustment.
05-13-2008, 01:49 PM
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Thanks for all of the responses. The valves have been adjusted, and the scan came back without any errors. It has an OBD I computer in it. the rockers are comp cam 1.6 - they were the same ones i used with the SR.
i don't believe the cam was degreed - as far as i know, it had a dowel pin that went into the timing chain, and that was it.
the only issue that was brought to my attention was that the mechanic had issues putting the harmonic balancer on (lack of knowledge on his part). I've bought a cable to link to my laptop so i can run my own scantools on it, and i'm going to check the fuel pressure on the car to see if that's an issue.
Before i had it tuned, it would sputter in the lower rpm range (2.5 and below) and surge at idle. i still randomly feel it sputter at low rpms (usually when i'm cruising in 5th gear or so)
Forgive my lack of knowledge, i'm still learning.
i don't believe the cam was degreed - as far as i know, it had a dowel pin that went into the timing chain, and that was it.
the only issue that was brought to my attention was that the mechanic had issues putting the harmonic balancer on (lack of knowledge on his part). I've bought a cable to link to my laptop so i can run my own scantools on it, and i'm going to check the fuel pressure on the car to see if that's an issue.
Before i had it tuned, it would sputter in the lower rpm range (2.5 and below) and surge at idle. i still randomly feel it sputter at low rpms (usually when i'm cruising in 5th gear or so)
Forgive my lack of knowledge, i'm still learning.
Last edited by spdracr713; 05-13-2008 at 02:07 PM. Reason: changed one of the comments
05-13-2008, 03:13 PM
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One more thing - the MAF sensor is not working - i'm not sure if it was ever working though. A replacement was swapped out, but it still wouldn't detect, so the car was tuned around it. The O2 sensors were also replaced.
05-13-2008, 05:17 PM
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the lifters are part# CCA-850-16 high energy hydraulic roller. the valves were adjusted with 0 lash while the engine was running.
the hr cam part # is CCA-07-468-8
the valve springs are part # 249-26918-16 (beehive)
the hr cam part # is CCA-07-468-8
the valve springs are part # 249-26918-16 (beehive)
05-14-2008, 08:41 AM
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If the maf isnt working and your not sure if it ever has, it sounds like your car was tuned for speed density. Which is fine but I would ask just in case b/c that could very well be your problem.
05-17-2008, 09:19 PM
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Some things i noticed when driving it:
-on cold start, engine idles low, and when coming to a complete stop, it will try to die unless you give it gas. it had about 1/4 tank gas in it - after filling the tank up, it started idleing higher around 1 - 1.2 where it was tuned for.
-gas mileage has dropped from 280-300 miles a tank (18 gallons) to 120 miles a tank.
rx8ss - yes it does have a map.
the shop that tuned the car readjusted the valves before they tuned it and put it on the dyno. i'm not sure what the final adjustment was.
-on cold start, engine idles low, and when coming to a complete stop, it will try to die unless you give it gas. it had about 1/4 tank gas in it - after filling the tank up, it started idleing higher around 1 - 1.2 where it was tuned for.
-gas mileage has dropped from 280-300 miles a tank (18 gallons) to 120 miles a tank.
rx8ss - yes it does have a map.
the shop that tuned the car readjusted the valves before they tuned it and put it on the dyno. i'm not sure what the final adjustment was.
05-17-2008, 09:31 PM
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Some things i noticed when driving it:
-on cold start, engine idles low, and when coming to a complete stop, it will try to die unless you give it gas. it had about 1/4 tank gas in it - after filling the tank up, it started idleing higher around 1 - 1.2 where it was tuned for.
-gas mileage has dropped from 280-300 miles a tank (18 gallons) to 120 miles a tank.
rx8ss - yes it does have a map.
the shop that tuned the car readjusted the valves before they tuned it and put it on the dyno. i'm not sure what the final adjustment was.
-on cold start, engine idles low, and when coming to a complete stop, it will try to die unless you give it gas. it had about 1/4 tank gas in it - after filling the tank up, it started idleing higher around 1 - 1.2 where it was tuned for.
-gas mileage has dropped from 280-300 miles a tank (18 gallons) to 120 miles a tank.
rx8ss - yes it does have a map.
the shop that tuned the car readjusted the valves before they tuned it and put it on the dyno. i'm not sure what the final adjustment was.
Buy a cable. Download Datamaster and collect data. Datamaster gives 20 free collects but once you try it you will buy it. If you collect data you can post the data here and I am sure anyone can help you find the problem. Sounds like it won't be hard to find. Also I see where Tunercat now offers a trial load so if needed they can fix the tune and send it to you so you can load it in your ecm
Good luck
Good luck
Last edited by BattleShip; 05-17-2008 at 09:40 PM.
