HP guestimate
08-24-2010, 03:38 PM
#1
HP guestimate
Let me hear some thoughts.
Current setup
454, dart aluminum 308cc heads, crane 741 Roller cam, roller rockers, weiand 177CID blower, no intercooler, 5psi. 8.4:1 CR. BG 1025cfm blower carb, and stellings dry exhaust.
Never had current setup dynoed, but my guess, is without the blowers, they should be around 500HP with the roller valvetrain and aluminum dart heads. With the blowers on at 5psi, im guessing they must be around 575-600. They push my non stepped 38 Fountain to 80mph on GPS.
Possible new setup (my buddy has 509's with 250CID blowers and he is going to 8-71) would be 250CID blowers, with intercoolers. All else the same setup, but refreshed. Possibly a little head work. 7.5-8 psi from the blowers
I'd like to get somewhere around 650-700HP. I am wondering if by adding the larger blower, and intercoolers, that would get me close.
Current setup
454, dart aluminum 308cc heads, crane 741 Roller cam, roller rockers, weiand 177CID blower, no intercooler, 5psi. 8.4:1 CR. BG 1025cfm blower carb, and stellings dry exhaust.
Never had current setup dynoed, but my guess, is without the blowers, they should be around 500HP with the roller valvetrain and aluminum dart heads. With the blowers on at 5psi, im guessing they must be around 575-600. They push my non stepped 38 Fountain to 80mph on GPS.
Possible new setup (my buddy has 509's with 250CID blowers and he is going to 8-71) would be 250CID blowers, with intercoolers. All else the same setup, but refreshed. Possibly a little head work. 7.5-8 psi from the blowers
I'd like to get somewhere around 650-700HP. I am wondering if by adding the larger blower, and intercoolers, that would get me close.
08-24-2010, 03:54 PM
#2
I am driving the 177 blowers at a 2.17:1 ratio. and getting around 5psi.
According to the boost chart i have, I should be able to turn the 250 blower to 1.55 or 1.65:1 to get 7.5-8psi.
So the 177 blower is around 12,000 RPM at 5500 engine rpm. The 250 blower would be around 9000rpm or below at the same engine RPM, but making more boost. Then of course add the intercoolers to the mix.
I guess what i am looking for is, is swapping blowers and adding the intercoolers going to get me where i want to be. Of course reliability is important, and I would have it all setup on a dyno to keep things safe. I would be using GM steel cranks, dimple rods, SRP forged pistons, and bottom end and heads fully studded with ARP fasteners, 10qt marine pans, oil stats, 3x18 oil coolers, MSD marine ignition, and quality head gaskets. I may add stud girdles also just for fun.
According to the boost chart i have, I should be able to turn the 250 blower to 1.55 or 1.65:1 to get 7.5-8psi.
So the 177 blower is around 12,000 RPM at 5500 engine rpm. The 250 blower would be around 9000rpm or below at the same engine RPM, but making more boost. Then of course add the intercoolers to the mix.
I guess what i am looking for is, is swapping blowers and adding the intercoolers going to get me where i want to be. Of course reliability is important, and I would have it all setup on a dyno to keep things safe. I would be using GM steel cranks, dimple rods, SRP forged pistons, and bottom end and heads fully studded with ARP fasteners, 10qt marine pans, oil stats, 3x18 oil coolers, MSD marine ignition, and quality head gaskets. I may add stud girdles also just for fun.
08-24-2010, 09:47 PM
#3
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I did a set up like that a few years ago and got like 575 out of it but it never stayed together. I would def go with much larger oil coolers. That is the biggest killer of a motor like that. IMO
08-24-2010, 11:31 PM
#4
Registered
I pretty much agree with everything you said, including the power estimates.
I think you will be right in the 700hp area with 8 psi from and intercooled 250. You may want to consider a small bump in compression and keep the boost around 7-7.5 psi. I would take the comp. to 8.8-8.9:1. This will allow you to slow the blower just a bit to help save it while not costing any power. Even with 9:1 and a good tune, you could run almost 10 psi boost on 93 octane.
Everything else sounds good. Is your cooler an 18" bundle, or is it 18" in total length? There is a big difference. If it has an 18" bundle length (the actual cooling tubes, not the housing), then it is large enough to support 700+ hp. If it is 18" in total length, then it will be close because the bundle is only about 14-15". It would still probably do the job. You may only have a cooling issue on extended wot runs. Good luck. Sounds like you are on the right track. Give me a shout if I can help in any way.
Eddie
I think you will be right in the 700hp area with 8 psi from and intercooled 250. You may want to consider a small bump in compression and keep the boost around 7-7.5 psi. I would take the comp. to 8.8-8.9:1. This will allow you to slow the blower just a bit to help save it while not costing any power. Even with 9:1 and a good tune, you could run almost 10 psi boost on 93 octane.
Everything else sounds good. Is your cooler an 18" bundle, or is it 18" in total length? There is a big difference. If it has an 18" bundle length (the actual cooling tubes, not the housing), then it is large enough to support 700+ hp. If it is 18" in total length, then it will be close because the bundle is only about 14-15". It would still probably do the job. You may only have a cooling issue on extended wot runs. Good luck. Sounds like you are on the right track. Give me a shout if I can help in any way.
Eddie
08-25-2010, 12:30 AM
#5
I pretty much agree with everything you said, including the power estimates.
I think you will be right in the 700hp area with 8 psi from and intercooled 250. You may want to consider a small bump in compression and keep the boost around 7-7.5 psi. I would take the comp. to 8.8-8.9:1. This will allow you to slow the blower just a bit to help save it while not costing any power. Even with 9:1 and a good tune, you could run almost 10 psi boost on 93 octane.
Everything else sounds good. Is your cooler an 18" bundle, or is it 18" in total length? There is a big difference. If it has an 18" bundle length (the actual cooling tubes, not the housing), then it is large enough to support 700+ hp. If it is 18" in total length, then it will be close because the bundle is only about 14-15". It would still probably do the job. You may only have a cooling issue on extended wot runs. Good luck. Sounds like you are on the right track. Give me a shout if I can help in any way.
Eddie
I think you will be right in the 700hp area with 8 psi from and intercooled 250. You may want to consider a small bump in compression and keep the boost around 7-7.5 psi. I would take the comp. to 8.8-8.9:1. This will allow you to slow the blower just a bit to help save it while not costing any power. Even with 9:1 and a good tune, you could run almost 10 psi boost on 93 octane.
Everything else sounds good. Is your cooler an 18" bundle, or is it 18" in total length? There is a big difference. If it has an 18" bundle length (the actual cooling tubes, not the housing), then it is large enough to support 700+ hp. If it is 18" in total length, then it will be close because the bundle is only about 14-15". It would still probably do the job. You may only have a cooling issue on extended wot runs. Good luck. Sounds like you are on the right track. Give me a shout if I can help in any way.
Eddie
08-25-2010, 01:12 AM
#6
Registered
Absolutely they are good for the power. I would definitely throw some ARP bolts in the rods. Be sure to have them resized after getting the new bolts. .However, consider this. You will spend about $200 on the rods with the new bolts and resizing. You will still have a press fit wrist pin. The other route is to replace the rods with something like a set of Scat's for about $400. There are several benefits. First, it is an H beam rod that is much stronger. Next, it has cap screws instead of stud type bolts. They are also much stronger. Lastly, you have a bushed small end. This allows you to run a floating wrist pin. This is the main reason for changing the rods IMO. I really don't mess with the stock GM rods anymore because they can be replaced so cheaply. I use to do a TON of GM rods. We would polish the beams, install bushings, etc. That was before the aftermarket rods were so affordable. Now, it just doesn't make a bunch of financial sense.
You have to look at the future. If you have any plans of maybe installing a 420 B&M or an 8-71 in the future, you will be pushing it on the stockers. At that point, you really should change them. The $200 you spent on the stock rods is now wasted because you have to replace them. You would be better off in the long run to replace them now if you have any intentions of future upgrades. Just a thought. Good luck.
Eddie
You have to look at the future. If you have any plans of maybe installing a 420 B&M or an 8-71 in the future, you will be pushing it on the stockers. At that point, you really should change them. The $200 you spent on the stock rods is now wasted because you have to replace them. You would be better off in the long run to replace them now if you have any intentions of future upgrades. Just a thought. Good luck.
Eddie
08-25-2010, 06:36 AM
#8
Absolutely they are good for the power. I would definitely throw some ARP bolts in the rods. Be sure to have them resized after getting the new bolts. .However, consider this. You will spend about $200 on the rods with the new bolts and resizing. You will still have a press fit wrist pin. The other route is to replace the rods with something like a set of Scat's for about $400. There are several benefits. First, it is an H beam rod that is much stronger. Next, it has cap screws instead of stud type bolts. They are also much stronger. Lastly, you have a bushed small end. This allows you to run a floating wrist pin. This is the main reason for changing the rods IMO. I really don't mess with the stock GM rods anymore because they can be replaced so cheaply. I use to do a TON of GM rods. We would polish the beams, install bushings, etc. That was before the aftermarket rods were so affordable. Now, it just doesn't make a bunch of financial sense.
You have to look at the future. If you have any plans of maybe installing a 420 B&M or an 8-71 in the future, you will be pushing it on the stockers. At that point, you really should change them. The $200 you spent on the stock rods is now wasted because you have to replace them. You would be better off in the long run to replace them now if you have any intentions of future upgrades. Just a thought. Good luck.
Eddie
You have to look at the future. If you have any plans of maybe installing a 420 B&M or an 8-71 in the future, you will be pushing it on the stockers. At that point, you really should change them. The $200 you spent on the stock rods is now wasted because you have to replace them. You would be better off in the long run to replace them now if you have any intentions of future upgrades. Just a thought. Good luck.
Eddie
What are your thoughts on vacuum pumps eddie? My buddy who runs blower motors also has been talking about adding them. Mainly just to help reduce crankcase pressure and oil leaks.
