Blown SC motor - need rebuild advice! - 450hp target
09-02-2007, 10:13 PM
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Blown SC motor - need rebuild advice! - 450hp target Ok, I got greedy - had a perfectly good and quick 95 LT1 with 120000 miles on it - I was running 7lbs of boost just fine - then tried to go to 9lbs on stock pistons - must have got a little lean - I think i put a hole in a piston - man i am pissed off and bummed out - but o'well -time for a rebuild!
Here is my plan for the rebuild based on what I have read so far - any feedback is welcome on my selection, especially on cam selection - my target is 450hp and 450tq at the rear wheels.
Pistons -Speed Pro Dished TRW-L2441F30
Rings -Total Seal TSR-T3690-30
Camshaft -Comp Cams 304 CCA-07-304-8
main bearings -Clevite 77 CLE-MS909HG
cam bearings -Clevite 77 CLE-SH290S
rod bearings -Clevite 77 CLE-CB663HN
Head Gaskets -Fel Pro HP FPP-1074
Lifters -Comp Cams Extreme CCA-8954-16
Rods -Eagle I Beam ESP-5700BBLW
Headers -Pacesetter PSM-72C2239
Main Studs - ARP ARP-134-5601
Balancer -ATI ATI-917268
Planning on using the stock crank.
Unsure if I am wasting money on the balancer
I am also playing with the idea of putting a 383 stroker kit on the motor, but don't know if the extra money is worth it or if I really need to.
Here is my plan for the rebuild based on what I have read so far - any feedback is welcome on my selection, especially on cam selection - my target is 450hp and 450tq at the rear wheels.
Pistons -Speed Pro Dished TRW-L2441F30
Rings -Total Seal TSR-T3690-30
Camshaft -Comp Cams 304 CCA-07-304-8
main bearings -Clevite 77 CLE-MS909HG
cam bearings -Clevite 77 CLE-SH290S
rod bearings -Clevite 77 CLE-CB663HN
Head Gaskets -Fel Pro HP FPP-1074
Lifters -Comp Cams Extreme CCA-8954-16
Rods -Eagle I Beam ESP-5700BBLW
Headers -Pacesetter PSM-72C2239
Main Studs - ARP ARP-134-5601
Balancer -ATI ATI-917268
Planning on using the stock crank.
Unsure if I am wasting money on the balancer
I am also playing with the idea of putting a 383 stroker kit on the motor, but don't know if the extra money is worth it or if I really need to.
09-03-2007, 07:19 PM
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if your going to run boost get a better cam, around 9 lbs a 230/236 blower grind from comp should be good anything over 9 id get the 224/236 like I put in mine, but if your only looking for 450 HP you sholdnt have a problem, I was making over 500FWHP on a stock motor with 9 lbs. it was over 400 at the rear with everything stock other than a blower and some bolt ons
09-03-2007, 10:23 PM
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Like this cam? something like this cam here?
COMP extreme CCA-224-236-14
Duration 224 236
Lift @50 with 1.6rrs .537 .556
Lobe center 114
Also, what about the stock balancer - will it hold up to 9lbs of boost? I am going to get it keyed at the machine shop when they do my rebuild - but wondering if I should just buy a new one?
COMP extreme CCA-224-236-14
Duration 224 236
Lift @50 with 1.6rrs .537 .556
Lobe center 114
Also, what about the stock balancer - will it hold up to 9lbs of boost? I am going to get it keyed at the machine shop when they do my rebuild - but wondering if I should just buy a new one?
09-07-2007, 06:30 PM
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I called comp cams - they suggested I go with
Comp Cams 07-468-8
576/570, 230/236, 113 lsa
if I don't stroke and
Comp Cams: 584/579, 242/248, 113 lsa
if i do stroke it out to 383
I also think I am going with JE pistons 131636 even they are about 300.00 more...they get a little closer to the 9.25 compression ratio I would like.
Comp Cams 07-468-8
576/570, 230/236, 113 lsa
if I don't stroke and
Comp Cams: 584/579, 242/248, 113 lsa
if i do stroke it out to 383
I also think I am going with JE pistons 131636 even they are about 300.00 more...they get a little closer to the 9.25 compression ratio I would like.
Last edited by real82it; 09-07-2007 at 06:39 PM.
09-16-2007, 09:42 PM
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I ordered the forged SCAT 383 kit today.....H beam rods and JE pistons - I figured I might as well build it bigger and strong while I am in there - really not that much more money.
So my heads are stock castings, ported/matched and polished with stock valves and LT4 springs.
Looking at the cam size suggested I realize I need to get new valve springs....can I avoid dual springs and having to cut the heads? Which springs?
Also, what about the valves? Should I get larger valves put into the heads or is it a waste of money? If larger, what size
2.00"/1.570"
or
1.985"/1.555"
So comp cams suggested I go with the Comp Cams: 584/579, 242/248, 113 lsa with the 383 - anyone have experience with a cam this size? What are the driveabilty charactoristics??
So my heads are stock castings, ported/matched and polished with stock valves and LT4 springs.
Looking at the cam size suggested I realize I need to get new valve springs....can I avoid dual springs and having to cut the heads? Which springs?
Also, what about the valves? Should I get larger valves put into the heads or is it a waste of money? If larger, what size
2.00"/1.570"
or
1.985"/1.555"
So comp cams suggested I go with the Comp Cams: 584/579, 242/248, 113 lsa with the 383 - anyone have experience with a cam this size? What are the driveabilty charactoristics??
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05-04-2008, 12:21 AM
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Well, I can't believe it was 9/07 when I started down this road -- but I FINALLY finished the motor, broke it in, tuned it myself (taught myself how to do it....with a lot of help from folks online...), and dyno'd it today:
449RWHP and 468RWTQ!!
I started with a target of 450HP - that is about as close as it gets!!
This thing is a blast to drive!!! Car actually has very good manners on the road - But I CANT stick it to the ground - time to get a set of drag radials!!
Here is my final build/change summary:
SCAT 4340 Forged Crank
SCAT 6" H Beam Rods
JE Forged 170817 Pistons - ~9.5.1 compression
Total Seal rings
Comp Cams 576/570, 230/236, 113 lsa
Comp Cams lifters
Canton Pan
Summit 58mm throttle body
Melling MEL-10552C
Pacesetter LT headers
Magnaflow Hi Flow Cats (converted to duals)
Dynomax muffler
I did not touch the heads in this build. I have previously ported/matched/polished the heads and intake.
Only problem I have is that my 600B only makes a max of 6lbs of boost now with the larger cam and displacement - i built this motor to handle a lot more - easily another 100+HP in there if I could get a
D1SC!
Hope to get to the dragstrip in ~1 month to see how this thing does!
449RWHP and 468RWTQ!!
I started with a target of 450HP - that is about as close as it gets!!
This thing is a blast to drive!!! Car actually has very good manners on the road - But I CANT stick it to the ground - time to get a set of drag radials!!
Here is my final build/change summary:
SCAT 4340 Forged Crank
SCAT 6" H Beam Rods
JE Forged 170817 Pistons - ~9.5.1 compression
Total Seal rings
Comp Cams 576/570, 230/236, 113 lsa
Comp Cams lifters
Canton Pan
Summit 58mm throttle body
Melling MEL-10552C
Pacesetter LT headers
Magnaflow Hi Flow Cats (converted to duals)
Dynomax muffler
I did not touch the heads in this build. I have previously ported/matched/polished the heads and intake.
Only problem I have is that my 600B only makes a max of 6lbs of boost now with the larger cam and displacement - i built this motor to handle a lot more - easily another 100+HP in there if I could get a
D1SC!
Hope to get to the dragstrip in ~1 month to see how this thing does!
05-04-2008, 01:12 AM
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Glad to see you went with the 383.
I'd always trade boost for displacement to make the same hp... now you have the option of dialing up the boost in the future without race gas.
I wen't a similar route... hoping for about the same numbers when it's all worked out. 396 NA. of course my 12.5:1 compression will prevent boost... N2O is sitting on the shelf right now.
I'd always trade boost for displacement to make the same hp... now you have the option of dialing up the boost in the future without race gas.
I wen't a similar route... hoping for about the same numbers when it's all worked out. 396 NA.
of course my 12.5:1 compression will prevent boost... N2O is sitting on the shelf right now.
05-04-2008, 01:17 AM
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Why is hp/tq falling off so soon? the TQ is GREAT at 4000, but by 6000 it seems the engine is out of steam.
Think its the cam? or the heads? is the blower getting inefficent there?
Very different TQ curve than my 396. I get 350 ftlbs from 2000+ and its pretty constant till over 5000 (hub was slipping, had to cut the run short, but the cam peaks at 6200rpms and she'll spin to 6800 when cold).
Do you have anyother dyno runs? I'm curious to see what it looks like lower and higher.
AFR looks ok, but maybe even a bit agressive for a blown application (12:1 in several spots... that's usually N/A territory). Did you play with the AFR at all? maybe look for 0.5 to 1 AFR less for safety? (assuming there isn't a big hp loss from running richer).
Think its the cam? or the heads? is the blower getting inefficent there?
Very different TQ curve than my 396. I get 350 ftlbs from 2000+ and its pretty constant till over 5000 (hub was slipping, had to cut the run short, but the cam peaks at 6200rpms and she'll spin to 6800 when cold).
Do you have anyother dyno runs? I'm curious to see what it looks like lower and higher.
AFR looks ok, but maybe even a bit agressive for a blown application (12:1 in several spots... that's usually N/A territory). Did you play with the AFR at all? maybe look for 0.5 to 1 AFR less for safety? (assuming there isn't a big hp loss from running richer).
05-04-2008, 03:35 PM
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Hmmm........don't know what is causing it to fall off that much.
The only other graphs I have are the original run yesterday vs final after I had tuned it (second attachment), and also final run yesterday vs my last 350 run with the same 6lb 600B set up (first attachment )- my 350 was stock head, stock cam.
Take a look and tell me what you think......it is interesting that the curve of the 350 and 383 lines are very similar, even though the 383 cam is very different......so totally new bottom end, yet similar slopes to curves.....think it is my heads or intake?
As far as the A/F - when i tuned it on the street before i took it to the dyno my A/F was about .5 lower across the range then on the dyno.......i asked the dyno shop about it and they said the dyno always reads about .5 leaner than a wide band taking samples before the cat (they put the sniffer in the tail pipe) - anyway, given that do you think I should still richen it up?
The only other graphs I have are the original run yesterday vs final after I had tuned it (second attachment), and also final run yesterday vs my last 350 run with the same 6lb 600B set up (first attachment )- my 350 was stock head, stock cam.
Take a look and tell me what you think......it is interesting that the curve of the 350 and 383 lines are very similar, even though the 383 cam is very different......so totally new bottom end, yet similar slopes to curves.....think it is my heads or intake?
As far as the A/F - when i tuned it on the street before i took it to the dyno my A/F was about .5 lower across the range then on the dyno.......i asked the dyno shop about it and they said the dyno always reads about .5 leaner than a wide band taking samples before the cat (they put the sniffer in the tail pipe) - anyway, given that do you think I should still richen it up?
Last edited by real82it; 05-04-2008 at 03:41 PM.
