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Discussion Starter #1
Hi all. Before I ask the real question, I have another. I noticed the posting date and time is showing tomorrow's date and about 5 hours ahead of the time here. I'm in Ohio and my computer's date and time is correct.

Anyway, my question is what size injectors would you recommend with the below listed mods. I recently added the 75mm BBK throttle body and spacer and bored out the factory intake to match. Since then, under full throttle shifts at redline, I get a very slight and short sound I believe to be detonation. I think I have not thrown off the air/fuel balance with the larger intake flow. I never had a peep of detonation before, even in 90 plus outside temps. So, I figure I need to increase to larger injectors. Also, do you think the fuel pump I have will be big enough. As always, thanks for all of your help. Mark
 

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I'd say go with 24lb injectors. Isn't the SN89 S/C the older paxton design? I'm dont think that you needed a 75mm TB I think it might be overkill on your engine.

Someone correct me if I'm wrong
 

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I would go 30 pounders and delete your FMU. And I thought the 75mm TBody was a little on the large side. I am running a 70mm BBK unit and I think it works well.

As for the date, I think it depends on where the server is located, not the date and time on your computer.

Mike
 

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Discussion Starter #4 (Edited)
You may be right about the throttle body being a bit big for this application, but I got it for nothing, so it was hard to say no. It works fine, great driveability. I noticed a huge difference immediately, especially with off-idle performance. It has a lot crisper throttle response, and strong, smooth acceleration. So, since this is the set-up, I wanted to be sure about the injectors and fuel pump sizing. There is no difference in price going from 19lb injectors to 24s, and going from 19lb injectors to 30s. But I wanted to be sure not to oversize them, if that's possible. Also, will the factory fuel rail support 30lb injectors, or do I have to resize that too? I know it will handle the 24 pounders. Thanks, Mark
 

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I still have the factory fuel rails with my 30 pounders. I have called Chris Johnson at Johnson Motorsports (who is doing my chip) and he said that they would support more than that (he said on my application, I could up to 42# and get rid of the FMU no problems, on the stock rails). I would like some other people's knowledge on this, to see if this is correct, but I know 30# is ok.

Mike
 

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Discussion Starter #6
Thanks, any other thoughts out there?
 

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I would go with at least 30's and also go with an external pump. You want to plan ahead so your not buying parts twice!! I have a T-Rex that I will get rid of cheap.....e-mail me if you are interested.

Chuck
 
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