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Old 04-17-2010, 08:23 PM   #1
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Default Nova P5, Bad Mod, with pics

I screwed up and bought a P5 off ebay months ago. It came with a pipe I was wanting and it was pretty cheap so I took the bait.

I bought an 8T, dropped that engine in and had a hell of a time getting a tune on it. The piston and sleeve had a great fit, wonderful compression, no air leaks, fuel lines and tank sealing were all OK. It had lots of flame-outs at random it seemed, mostly after a long straight run, at mid throttle it would go into a slobbering stumble it was so rich, temps were controllable, we chased the tune all over the map.

After blowing two plugs today, I decided to strip it down and give it a close look. I found what seems to be the work of a mad scientist in the block, there are notches cut in the BLOCK coming from the exhaust port and they extend around to about the middle of the transfer ports! A full 180 degrees of exhaust sweep behind the sleeve. The margin from the fang to the transfer port passages is maybe 1mm and when you look at the sleeve pics you can see I was getting exhaust bleed into the crankcase. It made for an interesting hunt to find this problem. I'm thinking at one time there may have been a sleeve cut to match this diabolical act, then they found out it was a screw up and put a stock sleeve back in it and sold it when they still had issues. The exhaust port is probably raised 1.5mm above where the sleeve port is.

What would possess someone to do this? Is this a normal mod of any sort? Maybe for a drag application?







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Old 04-17-2010, 08:57 PM   #2
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they modded the wrong port. i have seen booster holes/ports under the exhaust port but that looks to have the opposite effect. Instead of increasing air flow that looks to me (i am no expert) like it would decrease the airflow and actually not only produce drag but reverberate against the tune in the pipe.

just looked agian. They modded the block not the sleeve. That makes no sense whatsoever. looks like it would just cause a dead zone. Literaly trapping the air between the block and pipe. Man that is wack
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Old 04-17-2010, 09:16 PM   #3
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i hate to hear of anyone getting hosed sorry for your badluck but if you want a good modded engine especialy a nova give mark at powerhouse a call
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Old 04-17-2010, 09:29 PM   #4
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That's all I need to say.
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Old 04-17-2010, 09:59 PM   #5
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dude , that block is tooaaassst !! craziness


i have a bunch of good p5 blocks if you need a rebuild on the engine , i will waive the bench fee for ya if you want to get it repaired .
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Old 04-17-2010, 10:31 PM   #6
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dude , that block is tooaaassst !! craziness


i have a bunch of good p5 blocks if you need a rebuild on the engine , i will waive the bench fee for ya if you want to get it repaired .
Well that's an awesome offer! There's a guy here in town I talked to tonight and he said he thought he had a few blocks so we're going to swap it all over tomorrow if we find one. He seems to be known on some of the forums, that's how I came to meet him. Benny Smith is his name, he's been around this a lot longer than I have and I feel very fortunate to know him, one of the nicest people I've ever met. If that falls through I'll have to take you up on that I think.
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Old 04-17-2010, 10:43 PM   #7
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Widening the exhaust is an effective mod, going that wide does give the piston to much play and could be damaged.
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Old 04-17-2010, 10:47 PM   #8
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I'm not sure that's a mod. I think it's an onroad case.
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Old 04-17-2010, 10:49 PM   #9
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Widening the exhaust is an effective mod, going that wide does give the piston to much play and could be damaged.
The sleeve is dead stock, the mod is in the block outside the sleeve. Maybe at one time it was matched to it, but I'm thinking it was a fool with more Dremel bits than IQ points.
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Old 04-17-2010, 11:39 PM   #10
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Yep, just took a look at one of my old onroad cases, almost exactly the same as the pic. He probably broke a case, found an old onroad case and slapped something together. If the P/S are good, find an offroad case somewhere and swap it over.
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Old 04-18-2010, 01:20 AM   #11
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Yep, just took a look at one of my old onroad cases, almost exactly the same as the pic. He probably broke a case, found an old onroad case and slapped something together. If the P/S are good, find an offroad case somewhere and swap it over.
Someone may have tried to replicate an onroad then, these cuts are inconsistent in both the length, and the angle when comparing them. The right side reached the center of the transfer port and the left is about 3 to 4 mm rearward of the center. The right side also has a pretty notable difference in the transition from the notch to the exhaust port, the left side has a smooth blend.
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Old 04-18-2010, 04:33 AM   #12
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I have a P5 Case you can have. I had to drill one of the back plate holes out and tap it but it doesn't affect the sealing of the back plate.
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Old 04-18-2010, 04:44 AM   #13
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Those fangs on the exhaust port in the case are standared ive got 3 2009 off road Novas and a couple of older off road Novas that have those same fangs on the exhaust. They simply used the same cases that they use for onroad that uses 3 exhaust port in the liner. Check out the various pictures of Nova cases posted on this site and they have these fangs even on the off road motors. I believe the 2010 P5 case may not have these fangs any more. It was purly a cost thing to use standard cases.Martin.
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Old 04-18-2010, 05:17 AM   #14
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Check out excluesive nitro engine zone, All my reviews by Romuald 31. On this site and all the pictures of inside the cases are their, 2001bf,P3XS,P5XLT, and they all have these fangs. 2010 P5 also their which no longer have these fangs. Martin.
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Old 04-18-2010, 09:50 AM   #15
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Check out excluesive nitro engine zone, All my reviews by Romuald 31. On this site and all the pictures of inside the cases are their, 2001bf,P3XS,P5XLT, and they all have these fangs. 2010 P5 also their which no longer have these fangs. Martin.
Nice, I looked into the photos there. Looking in a zoomed view I could see more margin between the transfer and exhaust ports, someone has definitely done a touchup on these and crossed the line into too little margin. I'm also wondering if a pinch was done and a reduced diameter maybe contributes to the lack of sealing in that area, either way it's crap the way it is. It had awesome power as long as I could keep it running, run times were horrible to say the least though. I'm going to load up and head out to see if we can find a block and patch it up. May be time to buy that O'Donnell SS21 .
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