Holset questions...

[cschepp]

I have done some research and now wondering what your opinions are on a holset turbo? I am planning to run 500 hp and I think the hx35 will do the trick but here comes the fun part:

Will it fit the skyline stock downpipe for the gts? I know it will fit the stock exhaust manifold so I am not really worried.

Next thing is I wonder about is do I externally gate the turbo? I have mine externally gated right now but don't really know the benefits about this and wonder if going back to internal would be better?


Anyways any help would be appreciated as I am wanting to get this done asap

[Supraclean]

Hey Chris,

Im pretty sure I have the correct picture here:

http://www.google.ca/imgres?q=hx35+turbo+flange&um=1&hl=en&sa=N&biw=1024&bih=567&tbm=isch&tbnid=jK2s-qH0RCbEhM:&imgrefurl=http://www.orlandoforums.com/forum/turbo-%257C-supercharger-%257C-nitrous-sale/139477-holset-hx35-turbo.html&docid=mQkWsDw_fi_MqM&imgurl=http://farm3.static.flickr.com/2549/4089709563_50785b10c2.jpg&w=500&h=375&ei=X3gKT42VFcPe0QHQk_muDg&zoom=1&iact=rc&dur=203&sig=108591394534131549712&page=5&tbnh=160&tbnw=204&start=39&ndsp=8&ved=1t:429,r:4,s:39&tx=131&ty=95

If you look its going to need a new flange/ custom work to you downpipe. Might be smart to Vband it and new custom downpipe. Any exhaust shop should be able to help you out.

[cschepp]

If that is the case I would be better off to stick with the gt35r I have and stay top mount. I could get the exhaust shop to take care of things when everything was done

[BrianV8]

I had a holset on my car, Its long gone. Response is very poor. If you end up using it I highly recommend welding the internal wastegate flapper shut and go external. The waste gate that comes with it has like a 40 pound spring in it. Good way to blow your engine if you don't know that and using stock unit i never really liked how it all sits. IMO go garrett. A here is a little secret. For the power your making gt35 is too big, lag is too much. Want deadly response and all the flow you need gt30 FTW.

[cschepp]

Is there any that will work with a stock downpipe? I'm just wondering if ther is so I can avoid having a down pipe made.

[BrianV8]

nope you take it to an exhaust shop get a custom one made. Besides you want to retain the 3" diameter pipe right from the turbo, if you restrict it you already not very good spool time will become even worse

[Brendan]

The compressor housing of an HX35 hits then stock manifold so you can't bolt it on without a spacer.

Putting a spacer in means putting in longer studs... which means attemping to remove the stock studs... AKA breaking all of the stock studs and hating your life. If you're going holset you might as well count on getting an exhaust manifold or putting some work into your stock one.

[cschepp]

Thanks for all the help guys! From what I am reading and all the info put together I think gt35 will be my choice. Gt30 will have a great spool time but then that will limit my power options. For the gt35 what do you guys think I should go for on waste gate sizing? I was thinking anything between a 54mm to 60 mm would be in the range of what to look for

[BrianV8]

How much power to you plan to make? Once i do my build i'm aiming for 500whp if not a bit more 44mm should suffice. Putting down 400 now and getting the tiniest bit of creep on a 38mm. Key to having a great driving motor is pick how much power you want to make and build it to that level. Don't go too big or to small, try to size everything perfect. That will give you best response and performance.

[Zacho]

I'll make over 500 this year on a 30r, but it will be on meth and ~1.5 bar. This is besides the point though, I think using what you have is a much better choice than the holset.

Wastegate choice is important but so is wastegate plumbing. If your manifold has terrible wastegate placement I would size up, but I don't know what you have. A 44-46mm will be adequate providing you don't try and run quite low boost levels. A 60mm is massive and expensive, you don't need something that big.

[cschepp]

Well I plan to hit 500rwhp on 18-20 psi. I have built the rest for that level and need just a few things to finish it. Just some of the things I am unsure of i ask to make sure of just so I can get things right. I rather do it once and do it right!

[BrianV8]

imo cuz i'm doing the same build with same power goals, gt30 44mm waste gate. Done deal. Big power, sick response. Then you just gotta build a motor to handle it.

[BrianV8]

Biggest key number to turbo selection if flow rate. I did some research here for you and this is what i found. Keep in mind 1lb/min translate approximately to 10hp

gt3071 flow rate of 46lb/min = 460hp
gt3076 flow rate of 52lb/min = 520hp
gt35r flow rate of 65lb/min = 650hp

So there is way to see how flow translate to power.

[cschepp]

Wouldn't 500 whp surpass the 520 barrier? Does that mean 520 crank or? I will need to grab a waste gate(anyone know where to get a decent one?) I am also looking at turboes now as I have just found out the turbo I had is no longer mine(long story). But now I will need to replace the turbo and gate, any suggestions for suppliers?

[BrianV8]

as far as i know from research i've done in the past. 500hp is wheel hp, the variable making the 1lb/min = 10hp is drivetrain loss.