Hi guys,

I have a 2.8 built up. It breathes great up to 6500 rpm, and starts making good power around 2500. I like having a nice, peaky engine like this. I am thinking about installing a larger turbocharger, one sized appropriately for higher RPM power, so probably in the 3-6500 range. I am thinking about going for 1 bar pressure.

The engine will be able to handle it, don't worry about that. The heads flow great, the intake and exhaust flow even better, and the internals couldn't be better.

So.

Opinions on proper sizing? I don't mind having the engine up in the higher RPM ranges to make power, with the boost coming on a little late, kind of like the earlier 911's. Makes the car more fun to drive. On the other hand, the last thing I want is the car to be completely undriveable below 3000 rpm, as it is, it's 'behaved' at those speeds. So here is where I seek your advice. Any relevant data is appreciated. Compressor maps, opinions, crazy ideas, questions... all welcome. Another thought I had was to use two smaller turbos (Sized for about a 1.5L engine each, you see where I'm going with this) and put one on each exhaust header. Again... thoughts?

Thank you.

Steve

------------------


Gold 1986 GT 2.9L, Trueleo Intake/Headers, Getrag 5

I have heard alot of people who have had success running at least 7 lbs. of boost (i dont know how that translates into bar) on a garrett T3 from an 80's ford thunderbird. The turbo thunderbird had a 2.3, so it a close match for a 2.8. I have no idea about a twin-turbo set up and i'm not sure what kind of advantage that gives, unless it's a sequential setup.

7 psi is about 0.5 bar and the T3 size has worked well for me on a pushrod 3.4 L engine. I typically run about 0.5 bar on this setup but could very easily go higher.

quote Originally posted by MordacP: I have heard alot of people who have had success running at least 7 lbs. of boost (i dont know how that translates into bar) on a garrett T3 from an 80's ford thunderbird. The turbo thunderbird had a 2.3, so it a close match for a 2.8. I have no idea about a twin-turbo set up and i'm not sure what kind of advantage that gives, unless it's a sequential setup.

It sounds like you already have a turbo on your car? If you are looking for 1 bar (14.7psi) then the T3/T4 Hybrid is a good choice. If you have an external wastegate then go straight to a T4 and limit boost to 15psi. Then when you need more you can dial up the boost.

Just for giggles I'll suggest something a bit more absurd, how bout an HY35 or newer equivalent Holset. I suggest it because I've got one on my low budget XR4Ti track car running the aforementioned Ford 2.3L. I have no idea what it would do on the 2.8L so do some research before diving in. I swapped from the stock T3 which was nice cause it built boost quick but ran out of breath in the higher rpm range. The Holset on the other hand doesn't make squat for power below about 2500rpm on that engine but once it starts building boost it builds FAST, and is really fun. I'm around 15psi around 5k rpm, redline around 6.2k. If you check a compressor map on the Holset for the 2.3L it's not great, but not bad, Holsets are dead nuts reliable, and for the price (a good used holset that doesn't need rebuilding can be had for $2-500) there's nothing better IMO. Also, they can push 30psi without blinking if you have the boost bug and are good at least on a 2.3L up to 400+ Hp...

[This message has been edited by Raze (edited 10-10-2007).]

Here is another link to 4 turbo calculators:

http://www.turbofast.com.au/javacalc.html

quote Originally posted by Raze: Just for giggles I'll suggest something a bit more absurd, how bout an HY35 or newer equivalent Holset. I suggest it because I've got one on my low budget XR4Ti track car running the aforementioned Ford 2.3L. I have no idea what it would do on the 2.8L so do some research before diving in. I swapped from the stock T3 which was nice cause it built boost quick but ran out of breath in the higher rpm range. The Holset on the other hand doesn't make squat for power below about 2500rpm on that engine but once it starts building boost it builds FAST, and is really fun. I'm around 15psi around 5k rpm, redline around 6.2k. If you check a compressor map on the Holset for the 2.3L it's not great, but not bad, Holsets are dead nuts reliable, and for the price (a good used holset that doesn't need rebuilding can be had for $2-500) there's nothing better IMO. Also, they can push 30psi without blinking if you have the boost bug and are good at least on a 2.3L up to 400+ Hp...

That sounds like a neat idea, pretty much exactly what I'm looking for. I'm going to look into this on some more! Thanks! + for you

...Now to hunt...

I've seen pics of a fiero with a HX35 on the 2.8. I know talon and volvo guys that use this turbo as well. They're cheap and it'll probably suit your needs. Otherwise pick up a T04E 50 trim.

www.spooledmotorsports.com

They have Dodge, Ford and Chevy diesel turbos among others.

[This message has been edited by goatnipples2002 (edited 10-11-2007).]

hx35 would be quite large for a 2.8, if anything an hy36 or a hx30 would be a much better choice in the holset catagory.