Engine/Transmission (1998.5 - 2002) difference between turbos?

[jrandol]

I have an 02 truck with the Auto so I am assuming I have the HY-35 9cm housing turbo. What is the difference between this and the trucks with the manual transmission that have the HX-35 14cm. Do they get more boost? I dont understand, why wouldnt cummins use the same on all our trucks?

 

[Diesel Freak]

Originally posted by jrandol

I have an 02 truck with the Auto so I am assuming I have the HY-35 9cm housing turbo. What is the difference between this and the trucks with the manual transmission that have the HX-35 14cm. Do they get more boost? I dont understand, why wouldnt cummins use the same on all our trucks?

The HY35 on your truck is on the automatics because it spools slightly faster than the HX35. There are two reasons for this.



1. The HY35 has a smaller turbine... this can be translated to mean less mass which affects turbine shaft acceleration.



2. The HY has a 9cm housing... which flows slightly less than a 12cm HX35 housing (comparable to a 11cm HX35 housing if one existed). The Smaller housing spools the turbo faster.



Both turbos make about the same boost pressure when on a stock truck... 18-22 psi. The HY turbo goes into crosover before the HX35. What this means is that turbine drive pressure will exceed boost pressure on the HY35/9 before it does on the HX35/12.



Also after looking at both turbos disassembled side by side, the HY "looks" like it is also cheaper than the HX for Holset to manufacture.

 

[BarryG]

To add one more thing I "think" (dangerous I know) they use the hy on the autos because of the quicker spool up since the auto wastes so much energy on take off they use it to help compensate.

 

[Big White Beast]

Can you say EPA.........

In order for Dodge to get the auto's to comply with emissions standards they needed the quicker spool up. It's not a bad little turbo. Unless your going for big HP it will serve you well. I had an EZ with DD2's and it held up fine. I switched to a PDR HX-35 with a 12 housing and saw very little gain.



On the 02 I sent the HY to piers for modification. With only an EZ and 275' & 4" exhaust it's a smooth combo.



Garrett