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Discussion Starter · #1 ·
After struggling with the new combo blues, I finally got the car down the track N/A....but it may have been a little too quick for a nitrous motor
My combo:
2900# mustang
13.6:1 370 sbf with yates heads
nitrous cam
hogan 2x4 with prosystems dominators
2 applied foggers
chance 8" 6800 stall on the brake
1.80 glide
4.88 gears with 28x10.5s

1.41
3.99
6.14 @ 114
According to my log from my 75301 box I left on the launch limiter at 6200 and the convertor flashed to 6800.....but the rpms never dropped back down. I shifted at 8300 ( a little short) and it dropped to 7700 until it finished the 1/8 at 8100.
My concern is that the convertor will be way too loose when I put the bottles in it. I was expecting the convertor to pull it back into the low 6000 rpm range N/A. The 1st kit is a 28n 20f and I don't plan on running the second kit until it completely dialed in.
I do have a UCC 9" that went 5700 on the brake behind the same combo I could put in it. But, I at least want to see how the Chance does with the first kit on.
Your thoughts?
 

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I agree, you drove right thru the converter and it'll be worse when you spray it.
 

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EFI/N2O JUNKIE
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That seems like a lot of gear for that size tire and if you go down to 4.56's or lower the convertor problem is only going to get worse. Change the convertor, it is totally wrong for what you are doing.
 

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Discussion Starter · #5 ·
Mike, on the dyno my motor is a disgrace below 5500....however I am going to swap to a 29" tire after I get my beadlocks done. I don't mind turning it 9-9500 as I know it makes good power up there.......it just sucks replacing the springs and rods that much more often! I'll run it to the 330 on 1 kit just to say I did it and so I can send the log to Chance.....afterall they own the track I race at. After that I'll put Lenny's back in it and see how it does.
 

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EFI/N2O JUNKIE
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From my limited experience this is what I have seen: My 5500 rpm convertor will go to 6500 on a 150hp shot and 7000 on a 300hp shot. Now, I don't have a nitrous-only setup nor is it a N/A-only setup. it is kinda in-between so I can play-around once in awhile. Make a pass and log it. See what it stalls to off the line and what the rpm recovers to on the shift.
 

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You need to be looking more at like a 4.30/ 4.10 gear. 8 inch converter is to small. Remember that when you spray any engine the entire powerband comes down about a thousand rpms so you don't need to worry about buzzing it to the moon when you are sorting it out. Play around with that. Dont be scared of a low launch rpm because the engine doesn't make power down there. First of all the nos lowers the powerband and secondly the engine will run up to the stall speed anyway. typically a tad lower launch rpm will give the car a much better chance of a quick 60' when you are spraying. No nos, the opposite is true. You want to have the momentum going so that the strike of the tires does not knock the wind out of the engine's sail.
 

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Discussion Starter · #8 ·
Thanks for the suggestions Billy. I'm going to swap my 9" UCC back in it. My only concern is that both Lenny and Marty wanted 4:88's in the rear after I faxed them my dyno paperwork. I'm certainly not against going to a 4.30 though.....like I said earlier, I don't enjoy replacing valve springs.
 
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