I took my kids to some car shows this weekend. I hate mustangs but there was one at two of the shows that looked pretty good. Orange with black and chrome bigs and skinnies and was turbocharged.

I got to talk to the owner at the second show and asked him what kind of times it ran. He said he hadn't made it to the track because he was blowing head gaskets on his 351. He told me that he was making 30 psi of boost with a 78mm turbo on his 351. I instantly thought he was full of **** but my question is
"Is there any way in hell a 78mm turbo could make 30 psi on a v8?"

 

Absolutely, boost is only a measure of restriction and no one says the turbo cannot operate outside its efficiency range.

 

Definitely possible. And 30 psi may even be in the efficiency range for that turbo depending on how much cfm or lb/min it is flowing.

 

Look at a turbo diesel... they run that much boost and much more with a tune only. Their turbo's arent that big either.

Just like Pat said... its really only a measure of restriction. Just because he runs 30# of boost doesnt mean he wouldnt be better off with a more well thought out build running 25, or even 20#.

 

I understand boost is the measure of restriction but I was figuring that being a fairly small turbo(by todays standards) and so many guys running a much larger turbo and still 20-25 psi that it couldn't produce 30 psi on a V-8.

Anyhow it was a stang so 100 psi and it still would be slow.

 

Ford heads for the most part flow poorly when compared to Ls motors. It's not uncommon to see their blower setups in the mid to low 20's, so I could see 30 on a turbo setup even with a 78mm turbo. Turbos are actually much happier in the 20-30psi range if you look at a compressor map but LS motor make too much power up there! lol.

 

Exactly what kyle said

 

I knew LS head were the ****! Main reason LS kills Ford any day of the week.

I knew that a 78 would build some hella boost on a 4cyl I guess I should have known that an older ford wasn't much different in power then a tuner!

 

Have you ever said anything good about anyone's car or truck?

 

Engines that size can't hold 30psi at redline....but pin the wastegate shut and do a dig run and you'd be surprised how much boost a 78mm will make on a 351... Probably be near 50psi before the engine took a ****. Boost would fall off quick, but the turbo would kill the engine before it had a chance to start dropping off.