Turbo - OK, what do I do now?

[MWehmeyer]

I'll be towing a 7,000 pound 5th wheel and I'm trying to boost my HP without spending a lot of $$ or ruining my fuel mileage. :|



Until recently thought I was driving a 91. 5 but now it appears that I have a hybrid '91. It seems that the first owner installed an intercooler and custom intake piping. I just put in a 4" exhaust (3" down pipe) and was thinking of going to a 16cm2 turbine housing.



While reviewing the turbo threads here and checking some of the links I ran across a web site (Gillette?) that had some pretty specific information on the difference between the turbos on the IC and non-IC engines. So, went out to check the numbers and dimensions on mine. On the turbine housing all that is cast is the word 'Holset' and then some very small casting numbers right at the flange to the manifold; i. e. , no 'size' is present.



Checked the name plate on the compressor and it's a type H1C and it also has 'Holset' cast on the housing. Checked the dimensions - compressor intake is about 3" and the hose from the airbox to the compressor pretty obviously necks down from 4" at the filter end to 3" at the compressor. The compressor discharge measures 2" and is connected to the IC intake pipe with a hose and clamps. The IC intake pipe necks up from 2" to 3" about 6" from the turbo.



So the question is what do I do now? The web site I was looking at recommended upgrading the wheels in the compressor/turbine as a better alternative to the 16cm2 housing. Upgrading the wheels in the turbo sounds a lot more expensive than a $150 16cm2 housing.



Thoughts?

 

[JLEONARD]

You have what we call the "baby H1C" which was OEM for a non intercooled engine.

You have lots of options for upgrades, but you'll have to adapt your I/C plumbing and get rid of that 2 inch dia section.

Once you change to a larger compressor wheel, you WILL get some lag (been there) because you are driving more mass with more resistance. So you still may need/want to change exhaust housing sizes.



But just a turbo upgrade alone won't give you more power... you'll need to add some fuel either by pump tweaks, upgraded injectors or both...



Jay

 

[Sri Ram]

And, if you wish really hard, you'll get 15 rwhp, too :-laf :-laf :-laf

 

[TKingsbury]

I went to a 14cm housing and love it. It spools nice and quick, and my power comes on sooner. Your truck should have an 18 housing, so I would think a 16 wouldn't be THAT big of a difference. If you are looking for quicker spool and easier EGT control in the hills, go with a 14. My truck was nearly undriveable (think mid 70s 318) in the sierras with a trailer, even empty I had to come out of 5th on some hills! Now it is a completely different truck.

Travis. .

 

[JLEONARD]

And, if you wish really hard, you'll get 15 rwhp, too

Hey... it's 15. 6

Just think... if I intercooled it would be 17 :-laf



(That was the number from my emissions test dyno run. Must be what it took to maintain 30 mph in 4th gear)

 

[guava]

I just did the housing swap from stock to the 16cm and made no other changes. The real difference I've noticed is the spooling up and getting to the power that is there sooner. Its not dramatic but its there. It appears to have more a more distinct turbo noise too.

 

[Sri Ram]

(That was the number from my emissions test dyno run. Must be what it took to maintain 30 mph in 4th gear)

Yeah, I read that post. Hilarious! I also have low hp bragging rights. We'll see in October how my numbers have changed since the turbo/exhaust/intake mods Oo.