Quote:
Opening the exhaust too soon will be hard on the valve train
Can you give further comment on this?? Thanks for the education!
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| Nitrous oxide https://www.slantsix.org/forum/viewtopic.php?f=30&t=64297 |
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| Author: | Joshie225 [ Thu Jan 02, 2020 12:57 pm ] |
| Post subject: | Re: Nitrous oxide |
Naturally aspirated slants like a little more intake duration than exhaust, but exhaust volumes go way up when spraying so if there will be much use without spray I'd go with a single-pattern cam and chose duration based on operating RPM. I'd go slightly wider on lobe separation to give slightly earlier exhaust blow-down and not advance the cam quite as much as when NA. Opening the exhaust too soon will be hard on the valve train. To be more specific I would run 230-240° at .050" tappet rise, 108° LSA and install it with the intake centerline at 106° ATDC. If this is a drag car that's always on the bottle I'd add another 10° intake duration (240-250° at .050") and 4-6° more exhaust duration than that (254-256°). |
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| Author: | Rick Covalt [ Thu Jan 02, 2020 2:27 pm ] |
| Post subject: | Re: Nitrous oxide |
Quote: Opening the exhaust too soon will be hard on the valve train Can you give further comment on this?? Thanks for the education!
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| Author: | Joshie225 [ Thu Jan 02, 2020 4:18 pm ] |
| Post subject: | Re: Nitrous oxide |
With nitrous oxide injection, or other supercharging, the amount of fuel being burned goes way up. The fuel burn rate does not go up by much. This leads to large increases in cylinder pressure late in the expansion/power stroke. If the gasses are not expanded enough there will be a lot of residual cylinder pressure. That pressure is acting on the exhaust valve we are about to open. Try to open the exhaust valve too soon and the force needed to get the exhaust valve off the seat can break parts. Wait longer, in crankshaft degrees, and the cylinder pressure comes down to a tolerable level and the valve train lives. So don't open the exhaust valve too soon. Meaning don't run too much exhaust duration, too wide a lobe separation or too much cam advance. |
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| Author: | slantzilla [ Thu Jan 02, 2020 4:27 pm ] |
| Post subject: | Re: Nitrous oxide |
I have a nitrous cam Mike had ground and never got around to using it. I will post specs in the morning. It is not for the timid. I E Lash adjustment .018 .026 Gross Valve Lift .608 .600 Duration at .020 296 320 Valve timing at .050 In-Open 23 BTDC Close 63 ABDC Ex 74BBDC 26 ATDC IF you're going to spray a lot and try to run with Flyin' Ryan, you will need something like this. Yes, I would sell it so I don't keep thinking I need to try it. Quite honestly, I have found that a good N/A cam will work fine with spray. One benefit is that the motor will still run well N/A or on spray whereas a nitrous cam will leave a lot on the table trying to run N/A. |
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| Author: | bigc4406 [ Fri Jan 03, 2020 1:47 pm ] |
| Post subject: | Re: Nitrous oxide |
slantzilla wrote: I have a nitrous cam Mike had ground and never got around to using it. I will post specs in the morning. It is not for the timid. I E Lash adjustment .018 .026 Gross Valve Lift .608 .600 Duration at .020 296 320 Valve timing at .050 In-Open 23 BTDC Close 63 ABDC Ex 74BBDC 26 ATDC IF you're going to spray a lot and try to run with Flyin' Ryan, you will need something like this. Yes, I would sell it so I don't keep thinking I need to try it. Quite honestly, I have found that a good N/A cam will work fine with spray. One benefit is that the motor will still run well N/A or on spray whereas a nitrous cam will leave a lot on the table trying to run N/A. wow that is a nice cam . with that much lift what else is needed to be done to the head? and then what springs can you use a beehive or do you need a double/triple set up. seems like a lot of pressure for those long pushrods and high rpms |
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| Author: | Joshie225 [ Fri Jan 03, 2020 4:15 pm ] |
| Post subject: | Re: Nitrous oxide |
266/280° at .050" tappet rise is a very long duration cam. The torque without spray is going to be pretty abysmal. I would not attempt street use with that. |
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| Author: | slantzilla [ Fri Jan 03, 2020 6:37 pm ] |
| Post subject: | Re: Nitrous oxide |
It is a Comp cam Mike had done. The card is with it, and it has the model and serial number. You can probably call Comp or Mike and find out. I have a head set up for it. I just gave it to Mike and told him what I wanted. I have no clue what number spring, but I am pretty sure they are singles. |
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| Author: | bigc4406 [ Sat Jan 04, 2020 5:23 am ] |
| Post subject: | Re: Nitrous oxide |
slantzilla wrote: It is a Comp cam Mike had done. The card is with it, and it has the model and serial number. You can probably call Comp or Mike and find out. I have a head set up for it. I just gave it to Mike and told him what I wanted. I have no clue what number spring, but I am pretty sure they are singles. So does that mean you might sell the head and cam? 
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| Author: | slantzilla [ Sat Jan 04, 2020 9:12 am ] |
| Post subject: | Re: Nitrous oxide |
Unfortunately I won't sell the head. I bought the last good shortblock that was in my car when Mike last raced it. I need the head to go on it when I finally put it together. 
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| Author: | bigc4406 [ Sat Jan 04, 2020 7:49 pm ] |
| Post subject: | Re: Nitrous oxide |
slantzilla wrote: Unfortunately I won't sell the head. I bought the last good shortblock that was in my car when Mike last raced it. I need the head to go on it when I finally put it together. Well I might be interested in the cam if you want to sell. So intake to use for drag racing Clifford over offenhauser or can you get the offenhauser to flow |
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| Author: | slantzilla [ Sat Jan 04, 2020 10:35 pm ] |
| Post subject: | Re: Nitrous oxide |
I personally like the Clifford on a race car. Offy will give up quite a bit of high rpm power. If I can find it all I have a set of fogger nozzles and the plumbing at my shop. It is for a Clifford intake. |
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| Author: | bigc4406 [ Sun Jan 05, 2020 7:50 am ] |
| Post subject: | Re: Nitrous oxide |
slantzilla wrote: I personally like the Clifford on a race car. Offy will give up quite a bit of high rpm power. If I can find it all I have a set of fogger nozzles and the plumbing at my shop. It is for a Clifford intake. Well then I will start my search for a Clifford intake. I sounds like you have all the parts for a good time |
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| Author: | slantzilla [ Mon Jan 06, 2020 3:08 pm ] |
| Post subject: | Re: Nitrous oxide |
I have the intake for yhe fogger system on my car now with plugs in the holes. If I can find all the plumbing that goes with it I'd let it go too. |
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| Author: | bigc4406 [ Mon Jan 06, 2020 5:14 pm ] |
| Post subject: | Re: Nitrous oxide |
slantzilla wrote: I have the intake for yhe fogger system on my car now with plugs in the holes. If I can find all the plumbing that goes with it I'd let it go too. Well let me know when you are ready to sell Thanks |
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| Author: | slantzilla [ Mon Jan 06, 2020 6:52 pm ] |
| Post subject: | Re: Nitrous oxide |
Will do. |
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