Engine/Transmission (1998.5 - 2002) Hx35 good to what Horsepower?

[jkidd]

Did a search on limits of the stock turbo and did not find much.

I understand 35psi is max for "cool boost"



what HP is the supposed limit. I expect to rarely be at max, but want to know what to expect. I have a comp (tapped) clutch holds fine (checking out the sbc ofe. )



Should I worry about overboost or temperature to know the limits of the turbo. I will eventually want to switch to something that spools quick as I tow a lot (8k lbs)



hoping I can run the comp in EZ mode and the injectors and be fine, then turn on the box and go easy with it when empty.



any suggestions? what about the HTTurbo stage II or III for a hybrid?

 

[PC12Driver]

The 35/12 should be good to about 350hp ish. Mine worked well with an EZ and 100hp injectors (about 1200-1300 max egt). That was at about 32-35 psi at the manifold. When that boost was exceeded, you could actually see the pyro needle pick up speed toward the high side as the turbo choked.



A good mod for a little peace of mind when pushing the HX35 would be to drill the divider in the exhaust housing to get all six cylinders to wastegate. Stock only the back three dump, so the drive pressures/egts in the front cylinders could/would be significantly higher than the back. This also helps the wastegate keep the boost in check. There's other mods of the sort, but the drill method looks quick and easy.

 

[johncameron]

A good mod for a little peace of mind when pushing the HX35 would be to drill the divider in the exhaust housing to get all six cylinders to wastegate. Stock only the back three dump, so the drive pressures/egts in the front cylinders could/would be significantly higher than the back. This also helps the wastegate keep the boost in check. There's other mods of the sort, but the drill method looks quick and easy.

Interesting, I've never heard of that. I could definately use help in the EGT area.

 

[NoSeeUm]

Drill it how? Use a grinder to U out the center part?

 

[Hohn]

That's a good way to do it, just make sure you bull nose the edge, not knife-edge or it may crack when hot.

A die grinder and a carbide burr are your friends.

 

[Hohn]

Did a search on limits of the stock turbo and did not find much.
I understand 35psi is max for "cool boost"

what HP is the supposed limit. I expect to rarely be at max, but want to know what to expect. I have a comp (tapped) clutch holds fine (checking out the sbc ofe. )

Should I worry about overboost or temperature to know the limits of the turbo. I will eventually want to switch to something that spools quick as I tow a lot (8k lbs)

hoping I can run the comp in EZ mode and the injectors and be fine, then turn on the box and go easy with it when empty.

any suggestions? what about the HTTurbo stage II or III for a hybrid?

The HX35 can support a LOT of hp, but it all depends on how it's being used.

On a stock engine, it might support 350 hp @ around 32psi of boost.

With an aftermarket cam (like a Helix 2 or somesuch), it would probably support 425+hp or more @ around 32psi of boost.

Add nitrous, and now you are supporting 500hp @ 32psi boost-- all with the stock charger (usual headgasket and transmission/clutch warnings are assumed).

It's not just how much boost you have. Ask yourself why you even have boost? Is it because the engine won't use all the air the turbo can provide? Why, yes... I believe so. The surplus shows up as higher pressure. Make the engine flow more relative to the turbo, and boost goes DOWN even as power goes up.

Converting your 35 to a 35/40 hybrid should expand the HP ratings I mentioned above, but you'll find that at some point you just won't have enough drive energy from the undersized turbine to let the compressor do what it's capable of. That's why a full HX40 will support more HP than a hybrid 35/40. Unfortunately, full 40s are also known to be fragile no matter how much work has been done and who did it.

jmo

 

[KLockliear]

The only problem with still running the HX-35 above the 350hp level tends to be the drive pressure issues. The 3" outlet and 12cm (and even the 14cm) housing start to rob HP in the way of drive pressure pumping losses. 350hp is the upper limit I would consider recommending for a stock HX-35. Just my $. 015

 

[RustyJC]

I'm at 347. 2 rear wheel horsepower (see signature) and can hit 1400 - 1450 degF pre-turbo EGTs when towing (34 PSIG boost) up long, steep grades if I don't back out of the smoke pedal. For my application (towing a heavy 5th wheel), if I want more power (I don't really need it, but... . ), I'll be going to a larger capacity turbo.



Rusty

 

[Fishin Guide]

I was able to manage well over 400HP with a PDR35-12 up to arounf 2600 RPM. At that point, all bets were off and I am sure drive pressure was killing me.



It would go from a barely visible haze to coal train black. And the pyro would scream upwards.



The cam helps a ton!!



Dave

 

[PC12Driver]

That's a good way to do it, just make sure you bull nose the edge, not knife-edge or it may crack when hot.



A die grinder and a carbide burr are your friends.

Didn't you have some pictures of your modded housing around here somewhere? Your mods are what I had in mind when I posted above.

 

[Fishin Guide]

Didn't you have some pictures of your modded housing around here somewhere? Your mods are what I had in mind when I posted above.

I prefer a simple open spacer. It will fit easily and negates the need to punch a hole.



Dave

 

[KKlingbeil]

I prefer a simple open spacer. It will fit easily and negates the need to punch a hole.



Dave

That is a great idea... . never thought about that, but really a good idea... . This could also be done to a hy 35 right?? I no longer have one, but i have 2 or 3 buddies that do.

 

[Fishin Guide]

That is a great idea... . never thought about that, but really a good idea... . This could also be done to a hy 35 right?? I no longer have one, but i have 2 or 3 buddies that do.

Yes. You need longer bolts/ studs. The most restrictive part of the entire system is the wastegate. You could send an HX housing up to Piers and have a bigger wastegate flapper put in and witht the spacer, it makes a huge difference in driver pressure.



But I would only do it if you were cranked up on the fueling.



Dave

 

[jkidd]

wow this is great info. I would love to see pictures of how to drill the divider.

 

[johncameron]

wow this is great info. I would love to see pictures of how to drill the divider.

Me too.

 

[JRagland]

From everything I've found, this is the best thread on how to get the absolute maximum from an HX35 turbo. That said, I gave up and have an HTB2 62/12 in my garage now. There are pictures on that thread that are worth a thousand words.

 

[Fishin Guide]

wow this is great info. I would love to see pictures of how to drill the divider.

take the wastegate actuator loose. open the wastegate and peek through the hole. Instant access to make you own hole.



Dave

 

[KBaucom]

I had a little over 400 hp out of mine w/ bully dog stg 3, afe, exhaust, ats 3 peice manifold, DTT trany, edge comp, pushing about 35 lbs of boost

 

[NoSeeUm]

I prefer a simple open spacer. It will fit easily and negates the need to punch a hole.

FG, is this a custom or an off the shelf part?

Drill it how? Use a grinder to U out the center part?

That's a good way to do it, just make sure you bull nose the edge, not knife-edge or it may crack when hot. A die grinder and a carbide burr are your friends.

How big of a cut out would you recommend?



Jim

 

[Fishin Guide]

FG, is this a custom or an off the shelf part?





Jim

It's an off the shelf custom part! :-laf



Most of the guys working with twins will have one laying around. basically, it's a piece of plate with a big hole in the middle and the stud holes.



I got mine from Rip Rook. He's got all those parts now.



Dave