Turbocharging, what needs to be changed?

I am trying to learn a little about aftermarket turbochargers, for big block engines. I know a few basic things, such as low compression ratios, but don’t know if you need a special carb/intake setup to take the pressure from the forced induction. I am not looking for information on 20+ pounds, I am more interested in systems that run 7-15 psi. has anyone here worked with aftermarket turbos? any info would be great. thanks!

While I’m no expert, I think your problems are going to be in the form of proper carb jetting to compensate for the increased CFM and volume metric efficiency. Carb’s aren’t nearly as flexible as injectors are. Beyond that you need to get a set of crankcase extractors to provide draw for crankcase gasses/blow-by since you’ll have no vacuum when under boost.

I’ve been researching a turbo project myself. The problem I have is that no one knows how to manage low boost. Everyone and their brother is 100% geared to max output. I want to run a reliable setup that won’t impact durability with something like 5 lbs of boost. That means I need a small turbo that will spool up at low rpm …and run out of steam at a range below my normal max rpm @ WOT normally aspirated. All that it would do, and all that I want it to do, is move the power band lower in rpm.

No one can think that way …or at least I haven’t found them on my budget.

thanks for the info!

There is no one size fits all when it comes to something like this. Sometimes a camshaft swap may be necessary and if you’re planning on running a turbo and a carburetor this will require some work.

The turbocharger pulling through a carb. is easier. A blow-through setup is more complicated and requires the carburetor be entirely sealed or by using a special carb for this purpose.

I would suggest searching for a manual called “Maximum Boost” by Corky Bell and printed by Bentley Publishers. There’s a ton of info in there regarding principles and how-tos on forced induction systems.

I think you’d be better off looking at a supercharger for that application. Once you factor in turbo lag, you’d have a pretty narrow window of actual benefit from the turbo. Superchargers are “instant-on.” And unless you’re driving a very small car, 5lbs isn’t even going to be all that noticeable. Assuming you’re talking about a small car/engine (think Civic), 9lbs is a good blend between better performance and reliability. Most engines will take 9lbs easily without having to build them up.

This is probably the best advice you can get for your situation. Especially for a big block application.

You can count me in for another vote in favor of a supercharger instead of a turbocharger. Another benefit to supercharging is that superchargers are a lot easier to find, and because of that, you will probably be able to get more information on how to set up your engine to work with them. You also don’t have to tap into your oil supply like you do with most turbos. You can see a variety of superchargers for big blocks and small blocks in the Summit Racing catalog, and on their website I’m sure.

The light that burns twice as bright only burns half as long…

Speed costs money, how fast do you want to go??

dude, that’s like the fifth thred you have said this on, I am just trying to get some info, do you mind not doing drive by commenting?

superchargers cost 4000, a turbo unit costs about 400. Pipeing and other things would need to be added, but still it is cheaper.