twins?
 

will a 75horse injector spool a hx35/gt42 twin setup???

Well, You'll want some more fuel for good spool, it's really more around the pump! But why the GT42? Why not a S400 or 475?

i got that turbo for free!!!

I'm not sure that the sizing will work, Have you done some research on housing sizes and so on regarding twins?

yea idk i hope it works it would be nice to know if it would i know it is a 76mm idk the exhaust side tho

I think I would go a diffrent route. There's plenty of good combinations already proven to work! We run a GT42 for a single on a duramax, It's way to small for any twin setup IIRC. I'll do some research this afternoon

I bet it will spool like crazy, its a ball bearing and a smaller exhaust housing should spool right up know problem. Depending on what kinda power you want to make that set up should be good for 550 to 600hp depending on the turbine housing size I would bet. That gt42 can support 800 by itself with the right setup. Like I said depending on what you want your truck to do it might not be a bad set up. Thats just my two cents' I'm sure someone has tried it before.

A gt4294 is a 71mm and 4202 is 74mm.
BD twins are an s300g over a 66/74 they've been proven to over 600 horse, So I'd say you'll be fine with a Gt42, Depending of housing sizes and wheels. I was thinking a 42 was smaller than that!

If it's a GT42-02, that's the common primary used.

Only slightly smaller than the S400, it is externally gated. And that's great for fast spool and total boost control. Limit boost to 28-32psi.

This charger really comes to life with a larger secondary though.

The real cork in the system is that HX35. It's very restrictive on the turbine side. I would run an external gate or move up to a larger secondary. Even a HX40 would be a huge improvement in airflow and still spool well with that primary.

The HX40/ GT42-02 will support over 700HP easy. Run the top charger at 2:1.

Dave

I agree with Dave on this one. The compressor side of the the gt42 will be very capable and make a great set up. You hold backs will be the turbine side of each charger. The hx35 definitely wants an external gate, or it will choke up exhaust flow way too much.

If there is too much restriction in the exhaust side of your primary, it will make it a laggy combination. If you restriction flow at the bottom charger, it will necessarily decrease flow across the turbine of the top charger, making it harder to light. I would definitely recommend running a larger injector than 75hp as well. You will notice that spool up from zero boost is going to decrease, so you will want to increase exhaust volume to help keep spool up in check. Either more fuel from a larger injector and/or a cam.
Sean

this gt42 has and internal wastegate how will that work? will it be ok?

Yes, the internal gate will handle most anything a VP can throw at it. I know of a few HX40/ GT42-02 trucks kissing 600HP and no issues with boost control of the pimary.

Dave

Like dave said, the internal gate will be great for boost control on the primary and keeping it in the sweet spot of its compressor map. I would still add a pretty sizable wastegate to the hx35 though if that is the secondary you are going to run. They are a pretty small housing with a decent sized turbine wheel.
Sean

i have seen were guys run the wastegate on the manifold would this help and if so what kind of wastegate should i run on the manifold

Yes. Especially if you disable the internal gate. I would not go smaller than 38mm.

Dave

does anyone have any pictures of a setup for me?

Not to threadjack, but I have the same turbo, a gt4294, with an 1.01 externally gated housing. I would like to run as a single on a 12v, would it be possible to spool this before 2000rpm with intake and exhaust manifolds along with headwork? Truck is a 5spd as well.

Never thought about running it as a primary in a twin setup, seems a bit too small, maybe a 4202 like above.

:rockon: