Homemade turbo questions help please

[gtcobra302]

I have a 1989 Mustang GT. Fresh bottom end rebuild, ported an polished gt40 iron heads. Now on the the questions. I am planning on running a single turbo about 6-8 psi.

1. What is the problem with just running the turbo off one header only, do I have to run a cross over from one header to the other?
2. Do i put the massair sensor before or after the turbo?
3. Do I need an intercooler for that low of a boost level?
4. Are 24 lb injectors and a 255 lph fuel pump enough to do what I am trying to do?
5. I am going to be getting all parts from a junk yard. What would be a good car to get a turbo and accessories off of? Volvo?
6. On a turbo with an internal waste gate, that is what controls boost right?
7. I will need a blow off valve correct?
8. Do I need an fmu, boost retard box?

Thanks

 

[Michael Yount]

I'd ask the questions in the boost forum....or go to www.turbomustangs.com.

The Turbo off of a Volvo (2.1 or 2.3L 4 cylinder) is too small to work well with a 5.0L V8. Think of turbo's as pumps -- they have to be big enough to supply the needs of the displacement you're working with. Now two of those turbos -- one on each bank both blowing into the intake -- would get the job done if 6-8 psi is what you're interested in. Just about any single turbo off of a 4 cylinder engine is gonna be too small for the 5.0L.

When you power the turbo off of just one bank, you introduce completely different cylinder and exhaust pressure conditions from one bank compared to the other. Saab does this with one of their v6's, but I've yet to figure out exactly how they've made it work.

Intercooling helps cool the charge making it more dense (more power) and helping reduce the chances of damaging detonation. It's a good idea with any boost. If you can't do it, you'll have to run less timing and/or more octane and probably run quite rich -- not so efficient. I'd draw through the maf unless you have one especially calibrated for a blow through configuration.

Based on your questions, I think you have a lot more homework to do. Keep asking questions -- the biggest challenges with junkyard turbos come with sizing - getting the right one for the job. Get it wrong and you'll have one that's all of out breath at 4500 rpm or one that won't get out of it's own way UNTIL 4500 rpm.

 

[vristang]

As for running the turbo on only one bank of exhaust, there is no reason it will not work. It may not be ideal as the pulsations will not be as steady, but it will work.

An example
The head of my department in college had designed a carbon fiber v12. One bank was high compression and its exhaust supplied the turbo. The other side of the block was low compression, and only contributed at higher engine speeds and loads. I don't remember all the details on it, and I never saw it run, as I left school before it was completed. The professor had recieved numerous patents on this design.

 

[93-331-29psi]

The head of my department in college had designed a carbon fiber v12. One bank was high compression and its exhaust supplied the turbo. The other side of the block was low compression, and only contributed at higher engine speeds and loads. I don't remember all the details on it, and I never saw it run, as I left school before it was completed. The professor had recieved numerous patents on this design.

This is an interesting concept and would be even better to see in a production version diesel. Sounds kinda like GMs "on demand" systems they have out on their gas V8s. Combine this with alternative fuels and 6 or 7 speed transmissions and 50 mpg is not out of the question. Sorry, a lot off topic but interesting concept.

 

[Michael Yount]

Saab has sold a low pressure 3.0L V6 for a number of years now that drives the turbo just off of one bank, but pressurizes all 6 cylinders. It has intrigued me as well as it significantly simplifies all the plumbing associated with the application. I've just got to think that cylinder filling is gonna be impacted from bank to bank -- but perhaps not.

How 'bout someone give this a try and let us know how it works? In any event, some careful turbo sizing must be considered -- especially on the exhaust side vs. the compressor side. I had concluded, very simplistically, that a turbo sized to make 8-10 psig on a 2.0-2.5L four cylinder (very similar to the exhaust side of half the V8) would make 4-5 psig on a similarly tuned 5.0L V8.