Engine/Transmission (1998.5 - 2002) 12cm vrs 14cm TURBO exhaust housing

[jjohn]

I went from a 9cm HY35 to a "BD wastegated@42psi 14cm HX35"



With a the DTT 89H torque converter it can get a little smokey at these higher altitudes 5,000 to 10,000 foot range... plus “high summer air temps”(switch backs on mountain passes for example), not to mention the lag difference. I understand the advantages on the high end.



I want to try a 12cm housing just to compare the difference on the low end. Not sure if i need a wastegated 12cm for around $400 new... or a non-wastegated for around $150 range.



With my set up at 5000 plus feet I see 30 - 31 psi tops with the 14cm not even close to the 43psi rating label on the actuator.



Not sure if I would over speed a non-wastegated 12cm or not.



Just in case your wondering I’m Not selling the 14cm



any advice would be appriciated.



Thanks in advance JJ

 

[darkhorse]

You are much better off with the wastegate on either the 12 or 14 cm housings. A HX 35 should be limited to 35 psi max. They will pump more but you lose power to over heated air. The 12 cm unit should spool just a little faster but when I switched to my 14 cm unit, I didn't notice the change is spool time. If I hadn't ported the manifold & exhaust housing, perhaps the difference would have been noticeable. The advantage in the larger housing is lower egt's.

 

[Cooker]

I bet your WG is opening sooner than 42psi. I think you have enough fueling for over 32-33 psi on an HX35/14.



I agree I would not consider a non-WG housing in a 12 or 14.

 

[jjohn]

Thanks for the replies guys. You had me thinking… so at lunch today I pulled the hose and fitting from the compressor housing that goes to the waste gate actuator and replaced it with a 1/8 inch brass plug. Put it on 5x5 and went up a 7% grade, still only 31 PSI. Tonight I will use some compressed air in the actuator hose and see if it looks the actuator rod is working, as it should.



Is it common for a waste gate to stick partially open? This could be one possibility in my mind.



-or-



Everything is working as designed and… This is all the boost my set up will produce at this “altitude”



The Turbo is freewheeling with no apparent resistance; the shaft has no perceivable play in any direction. I’m no expert but all seem in order.

Thanks JJ

 

[nps]

Boost leaks?



Check your intercooler hoses - make sure they aren't rubbing or leaking.

 

[jjohn]

Everything looks good on the hoses.

 

[nps]

Can only think of two suggestions:



Drive down to lower altitude to see if boost builds higher, or



Pressurize the intake and see if/where there is any boost leaking - wastegate, intercooler, intake manifold, hose clamps, etc.

 

[TPCDrafting]

JJ I just put on Piers' ported 16 cm non-wastegated housing last week. Went from the stock 12 cm WG housing. The differences in my mind are very sutble. Max boost went from 30-31 psi to 28-29. I'm hoping for less back pressure and I do see somewhat lower temps. I also recently put on a BHAF and with the two I see about a 100-150 temp drop when towing. Basically I pulled 4 horses up from 6000 to around 8500 with the same power, temps and acceleration that I pull the usual 2 horses.



I could put down more information, but you'd have to promise to do another burnout at the next gathering. :-laf