How much boost can I run??
12-06-2002, 12:00 AM
#21
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allan4
what kind of pistons are in your motor? flat top ? forged? and what is the cc 's on the heads? are you sure the compression is that high? a standard 502 with stock heads 118cc is only 8.75/1
I ran my 540 with 10.75/1 compession and a b&m 174 making 2-3 lbs of boost it ran great on 94 with additive with no detonation
I ran it for two years like that
you never know until you try it put it on the dyno and see what it does
what kind of pistons are in your motor? flat top ? forged? and what is the cc 's on the heads? are you sure the compression is that high? a standard 502 with stock heads 118cc is only 8.75/1
I ran my 540 with 10.75/1 compession and a b&m 174 making 2-3 lbs of boost it ran great on 94 with additive with no detonation
I ran it for two years like that
you never know until you try it put it on the dyno and see what it does
12-06-2002, 10:17 AM
#22
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Cory, bottle was my first thought, but I want a sustained power, not just a shot. It just seems fake to me for some reason in a boat, if it is on a strip somewhere that's different. I do run a MSD 6AL and Holley electric fuel pump and Holley regualtor.
Back4more, I had thought about openening up the chambers, they are 119cc currently. GM High Perf Aluminum, rect ports, 2.25, 1.88. HOw much work needs to be done there?? How big do the chambers need to be to bring the cr down to mid 8's?? I assume that is way to much machining.
Gary, ggod point on the bravo. I have a buddy who will rebuild them for a reasonable fee, he is already excited about me running more power...HAHAHA. However, the busted drive would be next season, the $$ issue is now, but you are right. As far as waiting until it gets tired, that is what I was thinking as well. In one of the posts up top I was saying how it only has 70 hours and I hate to break it open right now. If it can't be done, then I am going to have to wait until the motor needs to be refreshed anyway. Also, I run a 24 Outlaw. these things don't handle very well at speed. I got lucky and dialed it in rather easily, and the attitude of the boat is pretty good. I have heard very bad about messing with the X. I have recently started asking about an extension box. Someone down in Baja land below has had luck with that set up. Curretnly trying to get info.
Puder, that would be great, but a cam change will probably give me only about 20-30 hp MAX, if that. Not worth risking the crappy idle and taking away from an awesome tq curve for that minimal gain. The motor itself is sweet, just needs a little more "ummffff".
Dustin, thanks a bunch, I will e-mail you if I have more questions, but I am thinking conservative and do not want to tear up this motor. Seems all the advice here is good, but you do this for a living and have a very good rep. Glad you chimed in!!!!
Hadley, Kieth Black hyperuetectic pop up's. The book on them is 9.9:1 with 118cc. I have 119cc, so I figured about 9.5-9.9. Is that right?? I really had no reason to be precise on figuring that cr figure, becasue I was going to run 92 or better octane to be safe. You are right about the dyno. That is what Byron and I were talking about. too bad I need to take the seat out and all that stuff to get the motor out. May be worth a shot anyway, but I REALLY do not want to burn up this motor. My money situtation is very tight, and If I toast this thing, that is going to be really really bad
How do you find EXACT cr numbers, I doubt I am far off, but maybe I am. Thanks everyone, great info, am learing alot. I am going to find more info on the extension box idea. Thanks again, I really appreciate the ideas. Allan4
Back4more, I had thought about openening up the chambers, they are 119cc currently. GM High Perf Aluminum, rect ports, 2.25, 1.88. HOw much work needs to be done there?? How big do the chambers need to be to bring the cr down to mid 8's?? I assume that is way to much machining.
Gary, ggod point on the bravo. I have a buddy who will rebuild them for a reasonable fee, he is already excited about me running more power...HAHAHA. However, the busted drive would be next season, the $$ issue is now, but you are right. As far as waiting until it gets tired, that is what I was thinking as well. In one of the posts up top I was saying how it only has 70 hours and I hate to break it open right now. If it can't be done, then I am going to have to wait until the motor needs to be refreshed anyway. Also, I run a 24 Outlaw. these things don't handle very well at speed. I got lucky and dialed it in rather easily, and the attitude of the boat is pretty good. I have heard very bad about messing with the X. I have recently started asking about an extension box. Someone down in Baja land below has had luck with that set up. Curretnly trying to get info.
Puder, that would be great, but a cam change will probably give me only about 20-30 hp MAX, if that. Not worth risking the crappy idle and taking away from an awesome tq curve for that minimal gain. The motor itself is sweet, just needs a little more "ummffff".
Dustin, thanks a bunch, I will e-mail you if I have more questions, but I am thinking conservative and do not want to tear up this motor. Seems all the advice here is good, but you do this for a living and have a very good rep. Glad you chimed in!!!!
Hadley, Kieth Black hyperuetectic pop up's. The book on them is 9.9:1 with 118cc. I have 119cc, so I figured about 9.5-9.9. Is that right?? I really had no reason to be precise on figuring that cr figure, becasue I was going to run 92 or better octane to be safe. You are right about the dyno. That is what Byron and I were talking about. too bad I need to take the seat out and all that stuff to get the motor out. May be worth a shot anyway, but I REALLY do not want to burn up this motor. My money situtation is very tight, and If I toast this thing, that is going to be really really bad
How do you find EXACT cr numbers, I doubt I am far off, but maybe I am. Thanks everyone, great info, am learing alot. I am going to find more info on the extension box idea. Thanks again, I really appreciate the ideas. Allan4
12-06-2002, 11:46 AM
#23
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Allan;
If you get some time get a cranking cylinder pressure reading. You might be able to change sticks (more bleed down) and get away with a blower. I'm going to the PRI show in Indy tomm and I'll talk with some of the reps about what you're trying to do. It sounds like if you went the NOS route all you'd need is a plug in retard box, a kit....and some cold plugs
If you get some time get a cranking cylinder pressure reading. You might be able to change sticks (more bleed down) and get away with a blower. I'm going to the PRI show in Indy tomm and I'll talk with some of the reps about what you're trying to do. It sounds like if you went the NOS route all you'd need is a plug in retard box, a kit....and some cold plugs
12-06-2002, 06:39 PM
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put the blower cam in it that i run so it will get rid of some cylinder pressure and put the blower on and just tease it with it. you have to remember you arent going to string out a 24 baja for a long time beacuse of the water being rough. JUST DO IT ARE YOU SCARED??????
12-07-2002, 07:10 PM
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Allan;
I talked with my engine builder and others at PRI show today. The "general" thought with your set up was that you can get away with about 5# of boost from a LARGER blower turning slower (like the 250). The key is getting a cam in that will bleed down those Cylinder pressures. Your current cam will not work. Also you need to get a baseline on where your cranking pressures are. Hope this helps.
I talked with my engine builder and others at PRI show today. The "general" thought with your set up was that you can get away with about 5# of boost from a LARGER blower turning slower (like the 250). The key is getting a cam in that will bleed down those Cylinder pressures. Your current cam will not work. Also you need to get a baseline on where your cranking pressures are. Hope this helps.
12-07-2002, 07:19 PM
#28
What cam are they suggesting? Is this with running an innercooler also. I would think this is like a band aid fix and not the prefered way. At least goes against the normal set up but I am no expert so what do I know. Interesting reading though. Man I wish I had a dyno in my shop to play with! 
12-07-2002, 08:40 PM
#29
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Thanks Cory, what are the specs on the cam? Merlin, what about your cam specs? Hydro rollers? This is turning into more hassle than it is worth it seems. Gonna take the fun out of it if I am worried about the motor all the time. Thanks for your help guys. Later.
12-07-2002, 08:41 PM
#30
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Allan You might consider installing a second fuel tank for racing gas when you use boost. Your 850 carb needs to have .130 needles to be on the safe side. JACK
