505rwhp/419rwtq - 348ci forged shortblock, Thunder Racing ported 5.3l heads!
08-10-2004, 12:29 AM
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505rwhp/419rwtq - 348ci forged shortblock, Thunder Racing ported 5.3l heads! Man, what a day! 
I finished installing a new 348ci shortblock in my car Sunday night. I kinda felt bad taking out the motor that was in the car because it was still running very well (8k miles and still going strong). But, more power called!
John (swapped2ls1) and I got the motor in and fired up, but was too late to dyno (neighbors get mad for some reason with loud noises coming from the shop around 2am lol). I took it for a quick spin down the road this morning to make sure everything was doing well. Other than not having traction at 100mph in 4th gear, the ride went well. lol So, onto the rollers it went this afternoon.
I started out with a real easy tune (rich and no timing). The initial pulls were 495rwhp/416rwtq. After a little tuning, the best it made was 505rwhp/419rwtq!! This was through a Moser 12-bolt, 4.56 gears, 3.5" driveshaft, 17" wheels, and full belts! I ran out of time to really dial the car in. I'll possibly have some time tomorrow to finish that up. Stay tuned for some even better #s.
DYNO GRAPH: 505rwhp/419rwtq graph
I let out a little early on that pull. The other graphs have the power carrying out to 7400rpms before falling off. Not bad stock rockers, lifters, and a hydraulic roller cam. Revlimiter is set at 7500rpms.
The specs on the motor:
Diamond 3.905" forged domed pistons
Carrillo 6.125" connecting rods
stock, polished crankshaft
JE rings
Federal Mogul main bearings
Clevite rod bearings
GM cam bearings
GM MLS head gaskets
ARP L19 head studs
Stock rockers and stock lifters are still being used.
Thunder Racing 5.3 truck heads, ported in house by Steve Stumpf
Manley 2.02/1.57 valves
Comp 941 valvesprings, titanium retainers
milled .030" for 12.5:1 compression
246/250 .632/.628 110lsa cam
The motor was completely assembled at Thunder Racing by myself and John.
Needless to say, I'm VERY pleased with the results. I can't thank Steve enough for the time he put into these heads. It was the very first set of LS1 heads he has ported. Not bad for a first try. I think Thunder has a very affordable cylinder head that is about to hit the market for both the LS1 and LT1s very soon! Also, huge thanks to John for the countless hours he put into this entire setup. I hope the ride in the car was worthwhile. 
I still cannot get over the power of these LS1 cars are making. If you would have told me a year ago I would have a 500rwhp stock cube motor (especially through my drivetrain), I would have freaked out. It just goes to show you what a well thought out heads/cam setup, plus a well-built bottom end will do for you.
I hope to head to the track one day this week. I need to before school beings for the semester (LSU)because I will not have time for anything when that starts up again.
Jason
I finished installing a new 348ci shortblock in my car Sunday night. I kinda felt bad taking out the motor that was in the car because it was still running very well (8k miles and still going strong). But, more power called! John (swapped2ls1) and I got the motor in and fired up, but was too late to dyno (neighbors get mad for some reason with loud noises coming from the shop around 2am lol). I took it for a quick spin down the road this morning to make sure everything was doing well. Other than not having traction at 100mph in 4th gear, the ride went well. lol So, onto the rollers it went this afternoon.
I started out with a real easy tune (rich and no timing). The initial pulls were 495rwhp/416rwtq. After a little tuning, the best it made was 505rwhp/419rwtq!! This was through a Moser 12-bolt, 4.56 gears, 3.5" driveshaft, 17" wheels, and full belts! I ran out of time to really dial the car in. I'll possibly have some time tomorrow to finish that up. Stay tuned for some even better #s.
DYNO GRAPH: 505rwhp/419rwtq graph
I let out a little early on that pull. The other graphs have the power carrying out to 7400rpms before falling off. Not bad stock rockers, lifters, and a hydraulic roller cam.
Revlimiter is set at 7500rpms.The specs on the motor:
Diamond 3.905" forged domed pistons
Carrillo 6.125" connecting rods
stock, polished crankshaft
JE rings
Federal Mogul main bearings
Clevite rod bearings
GM cam bearings
GM MLS head gaskets
ARP L19 head studs
Stock rockers and stock lifters are still being used.
Thunder Racing 5.3 truck heads, ported in house by Steve Stumpf
Manley 2.02/1.57 valves
Comp 941 valvesprings, titanium retainers
milled .030" for 12.5:1 compression
246/250 .632/.628 110lsa cam
The motor was completely assembled at Thunder Racing by myself and John.
Needless to say, I'm VERY pleased with the results. I can't thank Steve enough for the time he put into these heads. It was the very first set of LS1 heads he has ported. Not bad for a first try.
I think Thunder has a very affordable cylinder head that is about to hit the market for both the LS1 and LT1s very soon! Also, huge thanks to John for the countless hours he put into this entire setup. I hope the ride in the car was worthwhile. I still cannot get over the power of these LS1 cars are making. If you would have told me a year ago I would have a 500rwhp stock cube motor (especially through my drivetrain), I would have freaked out. It just goes to show you what a well thought out heads/cam setup, plus a well-built bottom end will do for you.
I hope to head to the track one day this week. I need to before school beings for the semester (LSU)because I will not have time for anything when that starts up again.
Jason
08-10-2004, 12:44 AM
#3
Awesome numbers jason. I know steve has good results with lt1 heads and I saw no reason why his ls1 heads wouldn't put out the same good results. Plus..he says he has some more tricks since he did these for ya..lol. I think its his attention to detail. Looks like ya'll put together another killer bottom end to go along with it. 500 rwhp with a hyd cam and 5.3 heads is just nuts...anyone done that before? Oh well..do some more tuning and quite the dyno racing...hit the track and lay down some 130+ mph times.
Now..slap steve up side the head and get him to finish my new stuff..lol.
Now..slap steve up side the head and get him to finish my new stuff..lol.
08-10-2004, 12:44 AM
#4
All I have to say is wow. That is one strong motor that is in your car at the moment 
. It was definitly worth the long hours we put in to build that motor, not to mention the 14 hours at the shop yesterday, because trust me it was well worth it to hear that thing start up last night and the ride in it this morning(trust me when i say this thing hauls ***....... it spun the whole way through fourth gear) 
I also would like to say thanks to steve(SAR2K) for the time and effort he put into the heads on this motor. Without your help on this motor as well, i dont think it could have made the power it did. All i can say is that if your first set of heads are making this kind of power, i can't wait to see what kind of things are to come from your heads!
. It was definitly worth the long hours we put in to build that motor, not to mention the 14 hours at the shop yesterday, because trust me it was well worth it to hear that thing start up last night and the ride in it this morning(trust me when i say this thing hauls ***....... it spun the whole way through fourth gear) I also would like to say thanks to steve(SAR2K) for the time and effort he put into the heads on this motor. Without your help on this motor as well, i dont think it could have made the power it did. All i can say is that if your first set of heads are making this kind of power, i can't wait to see what kind of things are to come from your heads!
08-10-2004, 12:48 AM
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I can shift faster than you.
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Thanks Gray!!
Tim, don't worry... track times coming VERY soon. You are right about Steve. I might pull these heads off for an "update" in a few months with all the advancements he has made with his ports since the time he did these! I don't know if anyone has made 500+rwhp with a 34x LS1 without using LS6 heads. It could be the first.. not 100% sure.
Again, thanks for all your hard work John. Lunch is on me the rest of the week.
Tim, don't worry... track times coming VERY soon.
You are right about Steve. I might pull these heads off for an "update" in a few months with all the advancements he has made with his ports since the time he did these! I don't know if anyone has made 500+rwhp with a 34x LS1 without using LS6 heads. It could be the first.. not 100% sure.Again, thanks for all your hard work John. Lunch is on me the rest of the week.
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Let me know what kind of trade in I can get on my solid roller motor... 
08-10-2004, 07:51 AM
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Originally Posted by Jason99T/A
Thanks Gray!!
Tim, don't worry... track times coming VERY soon. You are right about Steve. I might pull these heads off for an "update" in a few months with all the advancements he has made with his ports since the time he did these! I don't know if anyone has made 500+rwhp with a 34x LS1 without using LS6 heads. It could be the first.. not 100% sure.
Again, thanks for all your hard work John. Lunch is on me the rest of the week.
Tim, don't worry... track times coming VERY soon.
You are right about Steve. I might pull these heads off for an "update" in a few months with all the advancements he has made with his ports since the time he did these! I don't know if anyone has made 500+rwhp with a 34x LS1 without using LS6 heads. It could be the first.. not 100% sure.Again, thanks for all your hard work John. Lunch is on me the rest of the week.
I'm hoping to be way up in the 400s with the new cam...think its possible with a 90mm intake setup? Since you turned some wrenches on the car back at the Thunder Shootout last year...thats gotta be worth 20 RWHP right
08-10-2004, 09:05 AM
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Originally Posted by Chris ARE 385
Did I read correctly that you are using Comp 941s?
