350Gt Vq35De +T Build?

[andy_cliff]

Hey there guys. I have had a look around online about building up my current 350gt into a turbo daily.

I have seen/read many threads about the kits from the likes of Trust, HKS etc.

I dont exactly have the $8000 odd dollars that they want for those kits. I have come from the S-Chassis community

prior to owning the 350gt and was involved with a few sr20de+t builds over here in NZ.

I have a couple of questions to ask.

1. How much power can you make "safely" on the stock internals? as the internet proves again there are mixed opinions.

2. Would it be possible to use a turbo setup or even a twin turbo setup from the likes of the VQ25det or VQ30det/VQ30dett

3. How much modification/fab work would be involved in going the turbo route for the 350gt? as i am used to the common theme of needing to add oil lines etc for the SR20de +t

Thanks guys,

Andy

[scotty nm35]

VQ35's can blow at stock levels, you need to let us know your definition of safety. Sticking a turbo on and doubling the power will never be an exercise in long term reliability... probably 250-300kw if you have a VERY good tuner, and nothing drifts.

The VQ25det turbo setup is good, although the small turbo will choke the 3.5L. There are no 'bolt on' turbo's for the VQ25det manifold, although HKS made an adapter to use a T2 3037 on their 350z single turbo kit, using the same manifolds.

The fab work is easy enough for a competent fabricator, I managed to make my GTX3076 fit ok, but it was like putting a ship in a bottle with large pliers.

[PN-Mad]

Hiya mate.

I had a hks turbo kit on my vq35. I removed it and sold it off as the car was destined to be a family hauler. What Scotty said is true. What kills stock motors is the torque they are capable of producing once forced induction is involved. I only took mine to 6psi, with a very very safe tune. Motor survived the 10,000kms or so, and I had my fun. It survived drags, hill runs, and a bit of abuse.

Now why torque kills them is that mine had the ability to produce full boost when loaded up at 2200rpm. This was producing near 600nm, with might I add, the cam advance turned down to stop producing so much torque. All that going through the skinny little con rods has a habit of bending them. The crank is good for 700odd hp, so that's not an issue, it's the rods that have a habit of exiting the block.

[Hertz Donut]

(Probably as good a time to ask as any...)

PN-Mad, did you ever find the upper limits of the RE5 box? I know a shift kit will help and Nissan put them behind VK56s in Titans but I suck at teh Google and never found out what their max torque handling capability is. A lot of people focus on building a reliable FI motor but neglect the rest of the driveline.

Edited November 19, 2013 by Hertz Donut

[PN-Mad]

Nope. I got no where near it. I have a Transgo and external cooler. Your main enemy is heat if you know anything about auto boxes.

Scotty has had his fair share of box troubles..... Lol.

Put it this way, with a shift kit and cooler, the box will do anything that the stock motor will cope with IMO. If you start building the motor and upping boost, then don't expect the gearbox to cope with track work. It will be fine driving on the street, but 15 min track sessions will kill it quick.

[Hertz Donut]

Sweet, thanks.

[scotty nm35]

Alex is correct, the box is quite capable with just a shift kit and can handle a fair load of torque. If you step over the line though, the box is a 4k rebuild once you slip a clutch. I have rebuilt 2 boxes so far... I will be doing a manual conversion soon if I can find the manual V35 parts...

[andy_cliff]

Awesome, much appreciated fellas.

I wouldn't be looking for anything over the top. Just something a little more powerful than it is at the moment. The NA bolt on costs add up so in reality a turbo

setup wouldn't be a bad option in my head.

I would say 300-320whp would be more than enough.

From looking at the g35driver forum i found a bit of information in relation to what i will need for the build.

So at the moment it is clear i will need:

- HKS turbo adaptor if i can find one. If not some fab work

- Fuel pump (Walbro 255?)

- Tunable ECU

- Bigger injectors (440cc?)

- Wastegate

- Intercooler + piping

- Oil pan spacer

- Extended A/C line

- Braided oil feed and return lines

- All hardware for the install

Additional notes, run no more than 385whp or expect the boom. Run no more than 8psi on factory internals also.

Like i said, much appreciated guys. As expected this is something i do not want to mess around with so this helps a lot.

What are your thoughts on this? worth it simply for everything minus the turbo?

http://www.zclub.org.nz/viewtopic.php?t=3754&highlight=turbo

Andy.

Edited November 20, 2013 by andy_cliff

[scotty nm35]

There is no set amount of power it will go bang at, it all comes down to the tuner and fuel at the end of the day. If you were able to fill on e85 for example you could probably push 500hp all day without issue, but there are no guarentees in this game.

As for the list, a few things you don't need, like the pan spacer, A/C line, bigger injectors, fuel pump or ecu. Your stock fuel system may get you close to what you are after, but I could supply a 255 for $100 so it's a no brainer.

You will need a lot of awsome fab work though, not something Midas could knock up for you. It is quite tight in there.

I have a HKS 350z single turbo manifold here if you need one.

[PN-Mad]

E85 isn't going to magically make the rods take more torque.

Key is making power higher in the rev range and limiting the torque in the low end of the rev range. I never succeeded in this, and never went above 6psi. The hks kit and turbo isn't good tht way, it's very responsive with 3500cc in front of it.

Completely of quick notes

You'll need to fab the sump for a oil return.

Injectors run out about 5-6psi as does stock afm - you'll need larger if using Uprev

You'll need to cut the front fibreglass member and just push the AC line out the way

You'll need a catch can setup. These motors can be pretty loose, and like to breath.

Colder spark plugs

If looking at anything more that street cruising, a bigger radiator. Can't emphasise cooling enough. Big rad made heaps of difference in mine.

[PN-Mad]

Lol Scotty, your HKS manifold isn't just a rusty VQ25det set is it.....?

[scotty nm35]

It might be. lol. HKS thought they were good enough to use.

E85 will most certainly help the rods, but it is quite complex to explain my theory here. Let me just say, if you can stop the chance of detonation or pre ignition you will have a much better chance of keeping the block intact.

Like we would listen to your opinions anyway, sticking a turbo on for a week doesn't make you a guru mate.

[PN-Mad]

Hahahaha, I know what your saying regarding e85, and it certainly will reduce the chance of predet in the tuning process, and be more knock resistant than pootral. So it may well save a ham fisted tuner...

It will keep cylinder pressures lower, but that doesn't magically mean you have a 500hp motor. I wouldn't like to try it on my motor anyway.

[scotty nm35]

Any mod has risk attached to it, and no engine is safe from a bad tune, whether it be the tuner's fault, or more likely something drifted... Fuel delivery, timing drift, dodgy wiring, bad batches of fuel, any time you take an engine beyond what the manufacturer intended you gamble, that's why it's so addictive isn't it?

Ethanol won't magically save you if you push the car to the edge, (although my engine should have melted years ago) but at least you will never foul plugs, and no carbon build-up anywhere.

[scotty nm35]

E85 isn't going to magically make the rods take more torque.

Key is making power higher in the rev range and limiting the torque in the low end of the rev range. I never succeeded in this, and never went above 6psi. The hks kit and turbo isn't good tht way, it's very responsive with 3500cc in front of it.

Completely of quick notes

You'll need to fab the sump for a oil return.

Injectors run out about 5-6psi as does stock afm - you'll need larger if using Uprev

You'll need to cut the front fibreglass member and just push the AC line out the way

You'll need a catch can setup. These motors can be pretty loose, and like to breath.

Colder spark plugs

If looking at anything more that street cruising, a bigger radiator. Can't emphasise cooling enough. Big rad made heaps of difference in mine.

Not a bad list, the sump just needs a fitting alloy tigged to it, copy the VQ25 design perhaps. Braided oil feed from a T piece at the oil pressure switch.

If you have a decent (Walbro 460) high pressure capable pump you could get a lot more out of the stock injectors, well over the power OP was asking for. Might need a return line added and external reg.

You could simply bolt a stagea front on, that way the intercooler piping is taken care of...

Definitely catch can and colder plugs.

Cooling will definitely need to be sorted, these VQ's flash boil coolant in the bore at stock power.

[PN-Mad]

Stagea front won't do any good with piping. The throttle body is on the other side. So unless you want to run your nice cold post intercooler air past the 100 degree air coming out the rad, it's a no go.

Anyway, if you go ahead with it post up a build thread, and we can try to help with any issues, and you'll show the other V owners how to do it.

[andy_cliff]

Wow, cheers for all of the info guys!

Im quite surprised no one has done this conversion already?!

I have found a VQ30det manifold for $50nzd so far.

There are a few wrecked Turbo Stageas on Trademe that i will get the rest of the conversion from when i am ready to do it ($$$)

Addressing the notes from above:

You'll need to fab the sump for a oil return.

I was planning on doing what the Americans do and use a sump spacer as you can get them with the oil return on them already:

http://www.ebay.com/itm/OBX-Oil-Pan-Spacer-03-06-Nissan-350Z-Infiniti-G35-3-5L-/151160818159?pt=Motors_Car_Truck_Parts_Accessories&hash=item2331e309ef&vxp=mtr

Injectors run out about 5-6psi as does stock afm - you'll need larger if using Uprev

I am thinking about running the OEM GTR Injectors as they are 560cc from memory and fit straight in. Would there be any reason not to run 560cc injectors?

You'll need to cut the front fibreglass member and just push the AC line out the way

Sorry, what am i cutting the fibreglass member for?

Is it because of this:

From Turbonetics installation instructions:

" PREREQUISITE STEPS: Before getting your hands dirty while under the hood, there are 2 prerequisite steps.

See the following 2 sections for detailed instructions regarding A/C Tube Replacement and ECU Removal &

Shipping.

A/C TUBE REPLACEMENT: The first prerequisite step is to have a replacement air conditioning tube assembly

(included in the kit) installed by a professional A/C technician. This is necessary because the turbocharger is

located very close to this A/C tube in its factory location, so a replacement “shielded” tube assembly is supplied to

move it away from the hot turbocharger. HAZARDOUS: Do not attempt to perform this step without proper

training or equipment. Take your car to a local auto repair shop that is capable of discharging and recharging the

A/C system on your car"

You'll need a catch can setup. These motors can be pretty loose, and like to breath. Colder spark plugs. If looking at anything more that street cruising, a bigger radiator. Can't emphasise cooling enough. Big rad made heaps of difference in mine.

Thanks a lot! Every bit of info helps and this is fast tracking the system. Much appreciated.

Also just a couple of quick questions:

1. What size turbo would you guys recommend for the g35 and the power goals i am after?

As from memory one of you fellas said the VQ25 turbo would choke the 3.5 up?

2. Would this conversion be possible without taking the engine out? As i see the yanks seem to do their conversions without remove the engine.

Thanks again!

Andy

Edited November 29, 2013 by andy_cliff

[andy_cliff]

I just found a very, very helpful guide by Turbonetics. They use this for their "complete turbo kits" they sell.

http://www.treadstoneperformance.com/prod_imgs/installation/ul/install-41.pdf

Turns out i just need to be able to borrow a mates hoist to get around most of the build. Sweet!

[PN-Mad]

Wow, cheers for all of the info guys!

Im quite surprised no one has done this conversion already?!

I have found a VQ30det manifold for $50nzd so far.

There are a few wrecked Turbo Stageas on Trademe that i will get the rest of the conversion from when i am ready to do it ($$$)

Addressing the notes from above:

You'll need to fab the sump for a oil return.

I was planning on doing what the Americans do and use a sump spacer as you can get them with the oil return on them already:

http://www.ebay.com/itm/OBX-Oil-Pan-Spacer-03-06-Nissan-350Z-Infiniti-G35-3-5L-/151160818159?pt=Motors_Car_Truck_Parts_Accessories&hash=item2331e309ef&vxp=mtr

Injectors run out about 5-6psi as does stock afm - you'll need larger if using Uprev

I am thinking about running the OEM GTR Injectors as they are 560cc from memory and fit straight in. Would there be any reason not to run 560cc injectors?

You'll need to cut the front fibreglass member and just push the AC line out the way

Sorry, what am i cutting the fibreglass member for?

Is it because of this:

From Turbonetics installation instructions:

" PREREQUISITE STEPS: Before getting your hands dirty while under the hood, there are 2 prerequisite steps.

See the following 2 sections for detailed instructions regarding A/C Tube Replacement and ECU Removal &

Shipping.

A/C TUBE REPLACEMENT: The first prerequisite step is to have a replacement air conditioning tube assembly

(included in the kit) installed by a professional A/C technician. This is necessary because the turbocharger is

located very close to this A/C tube in its factory location, so a replacement “shielded” tube assembly is supplied to

move it away from the hot turbocharger. HAZARDOUS: Do not attempt to perform this step without proper

training or equipment. Take your car to a local auto repair shop that is capable of discharging and recharging the

A/C system on your car"

You'll need a catch can setup. These motors can be pretty loose, and like to breath. Colder spark plugs. If looking at anything more that street cruising, a bigger radiator. Can't emphasise cooling enough. Big rad made heaps of difference in mine.

Thanks a lot! Every bit of info helps and this is fast tracking the system. Much appreciated.

Also just a couple of quick questions:

1. What size turbo would you guys recommend for the g35 and the power goals i am after?

As from memory one of you fellas said the VQ25 turbo would choke the 3.5 up?

2. Would this conversion be possible without taking the engine out? As i see the yanks seem to do their conversions without remove the engine.

Thanks again!

Andy

Sure use a sump spacer plate - its a good fix. The only reason I couldn't is that the awd sumps are different to the RWD sumps- thus having to fab in the return.

560cc will be fine - as long as you can give your tuner the details of the injector (Latancy, min pulse V etc) it will work. Remember to go to a higher flow fuel pump too.

Im not familiar with the US kits, infact, I don't even know if they would work on a RHD car...

The HKS kit I am familiar with, you have to make a hole in the front composite reo to fit the intercooler piping through. All of the Z33 cars already have this hole and multiple kits use this. If its a G35 specific kit, then you'll be cutting, or they'll route it a different way.

I never had to de-gas the AC or anything, just pushed some of the lines at the side of the Rad out of the way to make room for the IC piping. Still worked fine, and still does.

Regarding the turbo - I'd suggest if your keeping the stock engine and not building it, something in the GT3076 range, with the biggest rear housing you can buy. Scotty will chim in, I think he runs a 1.02 tial or something. That would be ok, but you will need a fark off big external wastegate too: 50+mm, preferable 60mm. reason being is that your trying to bypass so much exhaust gas.

I suspect if you used a stock NM35 turbo you may well have uncontrollable boost, as the wastegate wouldn't flow enough.

yes, depending on the kit, it is very possible to do with without taking the engine out. We installed and took out the HKS kit without removing the engine. The most PITA is the headers, and the crossover pipe.

BTW - you missed out on a second hand complete HKS Z33 turbo kit that was for sale on Z club for $2100. It pays to keep your eyes out for the second hand market...

[scotty nm35]

First things first, where are you mounting the turbo? Are you planning to buy the Turbonetics kit?