I have a 305 stock compression stock heads but lots of other mods and the sn92 paxton, its intercooled. With out the intercooler i was seein 6psi with intercooler now seein 3 1/2 can i go with a smaller pulley? The pulley measures 3.2" was gonna go with 2.9" my timing is set at 2degrees they say stock is 6.Spark plugs stock heat range,with 1 step colder i had a major hesitation.Can i run the smaller pulley without any problems just tryin to get the boost back up to 6psi at least.

 

Losing 2.5 PSI by installing an aftercooler means it is either too small or you installed it wrong. You will make more power at 6PSI non-aftercooled than with 3.5PSI and an aftercooler.

 

backwards thinking....pressure drop is due to aftercoller volume is larger and the S/c cannot keep same psi but has more volume.

If the psi was raised when aftercooler was installed, then the aftercooler would be too small.

If i was the OP id get a wideband A/f gauge and Egt gauge for tuning and see whats the motor doing and tune according to that.

 

a guy on another website runs 12#s on his 305 no problems for him he;s also a memeber here but i cant think of his name here

 

backwards thinking....

 

i used to drag race turbo cars...guess i dont have a clue...

im new to domestic turbo/ and s/c apps....

wonder why my mk3 supra would eat 3rd gen f-bodies in its day....and only at 3.0L's or fury

 

It has nothing to do with racing. It is the laws of physics. In his case the aftercooler is a restriction which causes a pressure drop. Therefore, he needs to increase the boost (and heat) to make up for the aftercooler restriction. It is costing him HP.

There is no difference in putting a turbo on a lawn mower, import, chevy, or Mack truck. The theory and math is all the same.

Honestly, I am surprised that you posted this and also ask if a Holset HX35 unti will work on a 400 - 600 HP N/A engine. Anyone that has a clue about racing with turbos would know that the HX35 is way too small.

 

yeah, we all know 3.0 turbos are fast. Put the right size turbo on a thirdgen and race it against the 3.0 engine with the right size turbo. Keep the boost the same in both cars and see who wins.

I love how newbies try to show off.

 

may have a small leak somewhere. loss seems kinda high

 

I have lost bout 2 1/2 pounds of boost overall with the aftercooler, but i also have heard u can lose 1/2 pound from 90 degree bend which i have 3 and u can lose 1/2 or up to a pound with the aftercooler sound right to anyone? Im also running a small after cooler 12" by 12" by 3" so i didnt really think i would lose boost through it but i could be wrong.Any ideas?

 

"How much boost is safe?"

A flat track motorcycle racer always said, "You dont know how fast you can go until you crash".

In that light, "you dont know how much boost is safe until you blow it up."

 

i like that...

i run 14#'s max on my stock short block. it's all in the tune...

 

That is true. If the combustion process can't handle much more pressure because of the higher boost then you pull timing advance to light the charge later so that the peak pressure is not as high. Or you can run good gas, cool air and keep a decent amount of timing advance.

It is all about the octane, inlet air temp., head type, and tune (AFR and timing). Get it right and you can go fast. Get it wrong and this break.

 

86Z
TGO Supporter <---that's his name here lol

 

I'll back up what 86Z has to say. I'm running 14psi of boost with a twin intercooler setup and a D1SC procharger. I'm also running code $59 with a 749 ecm and a wideband O2 sensor. I keep my timing conservative in high boost and run a tad rich 12.5 and have had no problems at all.

I'd say you should be good for 6psi of intercooled boost no problem even with a fmu. If you go for more than that I'd ditch the fmu and go with a computer system that can read boost and adjust accordingly.

 

Where did all these new people come from?

-- Joe