Hi Doug, thanks for making it a sticky .... though the whole thread could be gone through and cleaned up quite a bit and knocked down to about 3 pages!!
Mustang_Geezer":3etbo5p4 said:
Can all the tubing be made out of regular exhaust pipe or do you need somthing of a thicker gauge, especially the "J" pipe?
AVOID at all costs thin walled pipe. The thicker, the better it can handle the weight, heat and stress. I have seen some pretty nice installations fail after about a year, because thin-walled pipe can't take the abuse. The scraps I welded together are actually from a Ford Explorer....and the wall thickness is abnormally thick, maybe about .080"?? Maybe it's just .065" but it is definitely thicker than plain exhaust pipe. Another nice thing is the scraps I used are all mandrel-bent pieces from the factory. I don't have a "crush" bent piece anywhere. Best thing is, it was all FREE!!
Mustang_Geezer":3etbo5p4 said:
Does it hurt to mig it all together vs tig welding? I have a mig welder and am good at it but dont have access to a tig nor have I ever tig welded somthing before.
MIG is just fine. I used the TIG on a lot of the intercooler pipe because that was much thinner wall thickness, and it is a lot easier to fill gaps with TIG than MIG if the pipes don't meet up perfectly. All my exhaust pieces were MIG'd, IIRC.
Mustang_Geezer":3etbo5p4 said:
Do you have to run a intercooler or can you start out without one.
An intercooler will allow you to run more boost, or lower octane fuel...depending. Any time you get the air going into the engine cooled down, you reduce the engine's tendency to detonate. If all you have is 91 octane fuel, an intercooler may help you run a few extra PSI of boost.
It also depends on the efficiency range of the turbo. If you are forcing a "too small" turbo to push more than it should be, then the air temps coming out of it will be VERY hot. An intercooler will help to prevent heat damage from all parts downstream.
Mustang_Geezer":3etbo5p4 said:
I know that the optimum compression is around 8.5:1 but what happens if you boost a higher compression engine?
Actually, 8.5:1 isn't the best for ALL engines. It really has a lot to do with the shape of the combustion chamber, whether the head is iron or aluminum, altitude, fuel octane used, engine operating temp, etc.
Boosting a higher compression engine will require higher octane fuel, and/or a system that injects alcohol and/or water.
Mustang_Geezer":3etbo5p4 said:
Cut the boost and timing back?
Reducing timing will reduce detonation but will also kill power if it is the only method used to prevent detonation.
SOME timing reduction is necessary no matter what, since a densely packed fuel air charge in the cylinder will burn faster no matter what (since the molecules are a lot closer together). But too much retard kills power.
Mustang_Geezer":3etbo5p4 said:
350 cfm carb Holley....right??
Depends on what you are comfortable with. My next carb is going to be a 2100 Motorcraft carb, because:
1) Has annular venturis already
2) has a solid float already
3) you can pull the top off to change jets without dumping fuel everywhere
4) The top is bolted down .... with a 5/16" stud! No bowl gaskets to leak fuel out of the bottom of the bowl
Cons are....single needle inlet looks to be about .080" or so...that could be a problem.
When being blow-through.....smaller carbs are a lot easier to tune than large ones. The better the pressure drop through the carb, the better the signal strength at the venturi. You want good, positive fuel flow through the venturi at all times. I think you can get too small, but even my 1.125" venturi 1-bbl carb would have been good for a high 12-second run with a good launch.
Mustang_Geezer":3etbo5p4 said:
To hook up all this to a very expensive dual exhaust system, can you just Y it back together from the down pipe?
Sure... many guys split the exhaust right after the turbo into a "Y". The build on my 32 valve 4.6 liter is going to have a "Y" immediately after the turbo outlet.
Mustang_Geezer":3etbo5p4 said:
And I know....turbocharging by Hugh Macinnes (sp)
A good book for the bare basics ..... it is getting a little dated, though. It could stand to be modernized a bit.
