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Pulley drop w/ minimal gain

A

Anthony Smith

New member
I am thrashing to get ready for a local end of the season drag event this weekend. I am determined to run into the 12's all weekend so I picked up a set of ET streets, 60# injectors and re-geared my trans to 3.29's. I set up the car for E85 and just got my 3.1 pulley from ZZP today. I uploaded my stock timing map to start with and bolted on the 3.1 and shorter belt. My problem is that going from my 3.4" to the 3.1" I only gained 1psi. On the 3.4 DDing all summer it has consistently run 9psi on my boost gauge verified by my MAP sensor at 162kpa. With the 3.1 the gauge shows a needle width under 10 and my MAP shows 170kpa or 10.1psi. I was expecting somewhere in the 11.5-12psi range so where did I go wrong? Is the stock TB a restriction in this range? Should I really only see 1 psi from 3 tenths on the pulley size? I always heard it was around 1 psi/.1". I was afraid the I wasnt going to be able to run the 3.1 with stock timing and 0kr but now I wish I had went with a 2.9" or something. If this is normal I guess it is time to crank the timing back up:th_confused:

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throttle body is probably a restriction, but as to what you'd gain? no clue.

Reducing restriction before the blower typically lowers post blower temps.
 
Brand new tensioner didn't make a diff. It is what it is I guess, I just cranked the timing back up to 19* with the 3.1. Ran a 12.84 @ 108 today so it must be doing something right
 
Holy ****, 2.8 with 22* with no ic? what else do you have to keep it out of KR? Is the boost line accurate on your dyno sheet? It shows almost 16 psi at full rpm? What does your map sensor read for manifold pressure? The highest its seen with the 3.1 was 172kpa I'm pretty dissapointed with that but it is making good power so w/e.
 


Anthony Smith said:
Brand new tensioner didn't make a diff. It is what it is I guess, I just cranked the timing back up to 19* with the 3.1. Ran a 12.84 @ 108 today so it must be doing something right
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wicked! which cam is that you have? you have a gen V or III?

also that cam could make a big difference in boost. like my NIC has a lot of overlap and leaks boost, do you have ported heads? that will lower boost as well
 
Anthony Smith said:
Holy ****, 2.8 with 22* with no ic? what else do you have to keep it out of KR? Is the boost line accurate on your dyno sheet? It shows almost 16 psi at full rpm? What does your map sensor read for manifold pressure? The highest its seen with the 3.1 was 172kpa I'm pretty dissapointed with that but it is making good power so w/e.
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Boost gauge is accurate, the one in my car and the one that the dyno company were dead on. Literally what you see in my SIG is all that I have done to the car, nothing else. It's a pretty fun ride at that the whp that it's sitting at right now. All I can say is that E85 loves timing from my experiences and of course requires a healthy fuel system. Walbro 255 pump, re-wire, and 60's were absolutely necessary.
 
TEK310 said:
wicked! which cam is that you have? you have a gen V or III?

also that cam could make a big difference in boost. like my NIC has a lot of overlap and leaks boost, do you have ported heads? that will lower boost as well
Click to expand...

My cam is the one they call the comp "xtreme energy" its almost similar to a xp but a little smaller. The supercharger is a III that I ported myself, the heads are stock
 


Why increase boost?!? Why not make power elsewhere?!? High Flow Catalytic Converter (or "Test Pipe"...basically, a piece of exhaust pipe that's custom cut & prepared to be swapped into the PLACE of where a catalytic converter SHOULD be)...& that's just if we're talking on something you need to drive as a daily driver, if we're talking organized track/drag strip/whatever, then justy open up those headers (in THIS context) Headers & Exhaust Manifolds are the same thing
 
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My cat REALLY doesnt do anything when its out in cold storage in case the car goes back to stock some day. I was being sarcastic, and my point was that im not running cammed with E85 and a 3.1 with stock manifolds or a stock cat on the car. We are beyond that at this point and have been for a while.
 


DEM0N said:
Why increase boost?!? Why not make power elsewhere?!? High Flow Catalytic Converter (or "Test Pipe"...basically, a piece of exhaust pipe that's custom cut & prepared to be swapped into the PLACE of where a catalytic converter SHOULD be)...& that's just if we're talking on something you need to drive as a daily driver, if we're talking organized track/drag strip/whatever, then justy open up those headers (in THIS context) Headers & Exhaust Manifolds are the same thing
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Hmm, headers and manifolds are the same thing?

Ok.

Test Pipe in place of a converter?

Hmm, because the factory converters on these cars actually aren't restrictive just like the catback. So, that would be a 1CHP gain and some noise getting rid of it.

Demon, you need to learn the platform.
 
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