I'm new to the turbo world and need some help?

[jdl1000]

I'm new to the world of turbos. I've decided to go twin turbo and need some help deciding which turbos to go with? I need to keep cost's reasonable and I will be building my own system being the car it will be going into, there is no built system for it yet. My set up is a 2V 4.6L in a 1987 fox mustang coupe. I used a 96 GT engine and did the PI head swap so now the compression is 10.5:1. I want to run about 8 psi for now but I want turbos that have the ablility to run higher numbers for a later build. I want them to spool up early to make the street driving factor fun. Maybe spool up between 2500-3500. Thanks in advance for any help.

[Ugly Duck]

Hey - I'm not too familiar with the mod motors and with what people are doing with them, but from what I know most of the turbo builds are singles due to the lack of space. There are a few twins out there, though.


You can't really go wrong with a Garrett T3 "60/63". This is the turbo from an '84-'86 SVO, Tbird Turbo Coupe (manual transmission), or Merkur XR4TI. "60" means either 60 trim or .60 A/R, which are two different things but both apply to the compressor section of this turbo, and "63" means .63 A/R turbine housing.

This turbo can support the 2.3 litre engine with 15-16 psi boost and actually flows more than these engines really need. Two of them are really nice on a 5.0, and they spool pretty early (2500 RPM max boost) while revving way out past 6000 RPM.

If you want something a little quicker spooling, I think you'd be happy with '86-'88 Volvo 740/760 turbos, pre-'88 Dodge turbos, or Saab 900/9000 turbos. These are 50 trim .42 A/R compressors and a .48 A/R turbine, and on a 2.3 litre can make full boost by 2000, though they start to choke things off above 5500 RPM.

If you want to wait a bit longer than 2500 and are willing to give up some space for the big top end hit, you could go with a pair of T04Bs and some of the smaller turbine housings, or T3/T4 combinations, so long as you use the .63 turbine.

[Cobra]

Just a little bit of info on the compression. 10.5 could be a little too much. I am only running 8.8 on my 5.0 with a single 60mm. You need to keep the compression low because when you build boost you will build compression.

[Ugly Duck]

Crap, I totally forgot to mention that. Yeah, unless you've got something up your sleeve, 10.5 might be a bit high.

HOWEVER...

Lots of guys with Volvos are adding turbos to their 9.7 and 10.3:1 motors, and running them up to 15 psi or even higher. These (aluminum) heads have pretty good burn characteristics, with lots of quench area and a tight chamber, so they can get away with it even with the 96mm bore. Since the OHC motors also have aluminum heads, which let you run another .5-1.0 point of compression, 10.5 might not be unreasonable for 8 psi on pump gas, or higher on race fuel.

[tobin]

WOW, so much info flowing from Duck and Cobra.....good info guys.

I spoke to a guy that builds custom turbo setups for the LT1's. LT1s come with 10.4:1 compression and the guy I spoke to said he leaves his just that way and gives about 15psi of boost to his engines. He said you just need to make sure the gas can keep up with the air and that the head gaskets can keep it all in. Plus, make sure you don't ping or predetonate, that kills turbo'd engines quick. get a BTM of some sort, you will need something to retart the timing on any boosted engine, anyone should tell you that.

Good luck.

[Disney Lincoln]

I wouldnt be scared with that compression with a small bore motor. I'd run a set of T3/T4 hybrids and LOTS of fuel pump and injector!

[tobin]

True that.....