408 380rwhp where did I go wrong
07-21-2018, 12:58 AM
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408 380rwhp where did I go wrong I have a 98 z28 that I have put a 408 bottom end in. It has Ai 226cc ls6 heads and a ls6 intake. The cam specs are 244/254 113+2 lsa .620/.620 lift. Johnson 2110 litters with iirc .035 preload, 17/8 speed tech headers and y to magnaflow catback the stall is a fti 4000 hard hit. Rear end for 9 4.11 gears 30" tire dyno was right at 380/380 was thinking about fast 102 for my current heads but have been thinking a head swap is necessary maybe some mms 235 if I can wait that long of upgrade to a nice ported ls3 topend? The converter was unlocked with those numbers
07-21-2018, 08:16 AM
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Obviously those numbers are way low for your build, but it's possible the dyno is just messed up too. If the car runs fine, and timing and AFR are within spec, I'd see what it runs at the track first. You trap speed will quickly confirm weather there's an issue or not
07-21-2018, 08:24 AM
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What type of dyno? Dyno dynamics read lower than mustang dynos and dynojets.
07-23-2018, 02:25 AM
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No track time more of a grudge street car. I would have to find my paper work for the compression ratio. I was told by my tuner on the dyno the converter was flashing to 5500. I also have to try multiple times to get the car to start or hold the key excessively long and it still may not start. Does run strong but still not as strong as I expected.
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07-23-2018, 10:15 AM
#8
I have a 98 z28 that I have put a 408 bottom end in. It has Ai 226cc ls6 heads and a ls6 intake. The cam specs are 244/254 113+2 lsa .620/.620 lift. Johnson 2110 litters with iirc .035 preload, 17/8 speed tech headers and y to magnaflow catback the stall is a fti 4000 hard hit. Rear end for 9 4.11 gears 30" tire dyno was right at 380/380 was thinking about fast 102 for my current heads but have been thinking a head swap is necessary maybe some mms 235 if I can wait that long of upgrade to a nice ported ls3 topend? The converter was unlocked with those numbers
07-23-2018, 02:27 PM
#9
As stated before the power seems low but there could be other variables. What transmission? 4L60?
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07-23-2018, 06:52 PM
#10
I have a 98 z28 that I have put a 408 bottom end in. It has Ai 226cc ls6 heads and a ls6 intake. The cam specs are 244/254 113+2 lsa .620/.620 lift. Johnson 2110 litters with iirc .035 preload, 17/8 speed tech headers and y to magnaflow catback the stall is a fti 4000 hard hit. Rear end for 9 4.11 gears 30" tire dyno was right at 380/380 was thinking about fast 102 for my current heads but have been thinking a head swap is necessary maybe some mms 235 if I can wait that long of upgrade to a nice ported ls3 topend? The converter was unlocked with those numbers
We both have old heads, old intake and old TB's. I purposely went with 10.8:1 compression because of future boost. Converter is a Yank 3600. My gears are 3:73.
I made 410 RWHP. Not sure what the RWTQ was. (Not a Mustang dyno)
.
07-23-2018, 08:27 PM
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07-24-2018, 09:12 AM
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07-25-2018, 07:06 AM
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Too small of an intake, heads for cubes and cam. That y I bet is small too.
245 or Ls3 heads be best on 408. A flowmaster dual 3 into single 4 with a free flowing muffler be best too.
245 or Ls3 heads be best on 408. A flowmaster dual 3 into single 4 with a free flowing muffler be best too.
07-25-2018, 12:02 PM
#17
What's your compression ratio......and did you do any dyno runs on the same dyno BEFORE you installed the stroker? BTW.....your cam is very close to the hydraulic cam that was in my 429ci LS3.....that engine had 12:1 compression.
It could be that you've over-cammed the engine......or that you were just on a stingy dyno.
KW
07-25-2018, 06:44 PM
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not yet. Cam timing wasn't verified just lined it up dot to dot as I do with all of my other builds no advance or retard but I didn't degree it so that could be it
You're in the same boat as me....except my build was intentional. But a close comparison. I also expected more power than mine made.....
We both have old heads, old intake and old TB's. I purposely went with 10.8:1 compression because of future boost. Converter is a Yank 3600. My gears are 3:73.
I made 410 RWHP. Not sure what the RWTQ was. (Not a Mustang dyno)
.
We both have old heads, old intake and old TB's. I purposely went with 10.8:1 compression because of future boost. Converter is a Yank 3600. My gears are 3:73.
I made 410 RWHP. Not sure what the RWTQ was. (Not a Mustang dyno)
.
What's your compression ratio......and did you do any dyno runs on the same dyno BEFORE you installed the stroker? BTW.....your cam is very close to the hydraulic cam that was in my 429ci LS3.....that engine had 12:1 compression.
It could be that you've over-cammed the engine......or that you were just on a stingy dyno.
KW
It could be that you've over-cammed the engine......or that you were just on a stingy dyno.
KW
07-25-2018, 08:38 PM
#20
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Do a leakdown check....