chimmike

Okay so I was sitting and thinking about this....but before I can confirm it's definitely viable by looking under the truck at the clearances....here's the deal.

Turbos: use the twins from a stock Nissan 300zx twin turbo. They're essentially sized between a t2 and t25. Excellent for response on the 3vze, and they're SMALL and internally wastegated.

These turbos would allow you to run without an intercooler. You could flow the compressor outlets into a Y to the afm directly. Maybe use something like meth injection for high power use, low speed situations (such as rock crawling or off road crawling where there's minimal airflow into the engine bay) to cool intake temps and boost power.

Anyways....I think these turbos are small enough to allow them to fit without needing crazy exhaust piping, and then exhaust could easily be routed out either side without being reconnected.

This setup could easly produce 50% more useable torque, especially in the low end. I believe the stock wastegates run 7psi. Add in an Apexi SAFC and some slightly larger injectors and you've got a super low dollar twin turbo motor (you could still use the STOCK headers and run heavier piping with garrett flanges a little further back to the turbos.)

Oil lines might be a little more tricky, might need a sump pump to pull the oil thru the turbos and push it back to the pan. Sender would be fairly easy.


So am I crazy? Bumpin, wanna give this a shot? haha

Tdubbs05

well if you've got the hardware sitting around then i think you've got something going for ya. otherwise i think you might be putting in a little too much work into a 3.0. but hey if you've got the means what's stopping ya!

chimmike

well, I have a friend who has a VG30DETT sitting around. However I don't know if he plans on using the turbos or not.

lines and fittings would probably run me around $100-150 for oil lines. I'd have to look into some sort of low capacity sump pump or something to return the oil to the pan, unless the turbos can stay higher than the pan for gravity drop.....

I don't have an SAFC though. I'd have to also get a set of stock injectors and send them to RC engineering to get drilled out to flow more. Plus getting garrett flanges=$50 and then turbine discharge flanges would be expensive, plus extending the o2 sensor.

Other than that..........It's pretty feasible and could reasonably be done for under $1000 even having to buy the turbos. Mandrel bends and creative fabrication could be used for the piping, and flexible hosing could be used for intake piping down to the compressor inlets instead of hard piping, mounting twin smaller filters at the back of the engine bay for water protection.

dcg9381

How you gonna control timing / fuel? Trust me.. The hard part isn't getting the turbos to bolt up.. It's what happens once the key is on!

mastacox

Yeah, getting turbos that theoretically might "work" is the easy part, the hard part is building the engine to handle the power (especially new HG and ARP studs), along with fuel and timing control.

chimmike

Well I mentioned before I can use an SAFC for fuel. As for timing, leaving ignition timing at stock base settings should be more than fine, especially considering how closely gapped the plugs are stock. If it was a problem I could pick up an MSD boost retard box.

Fuel control would of course not be perfect, but with my turbo experience and keeping it at a safe 12:1 or so would be safe without being overly rich and risking hydrolocking the motor.

Oil pressure might be a factor, might have to run a thicker oil like a 15w40 or so.....but even still......It would make excellent power all around and wouldn't OVERpower the stock transmission and stuff. Might cause a little wheelspin though ahaha

Just a proposition, I don't know if I want to attack something like this yet.

mastacox

Running 7psi of boost you would definitely need to retard the timing since a N/A motor advances the timing as far as possible to get maximum efiiciency. On my engine I have to run 6.5 deg. timing retard in the high boost areas (over 4-5 psi) to get rid of knock.

Overall it sounds like you would be able to make it work for not too bad a price (relatively), but don't plan on doing it for anywhere near $1000. My conservative estimate would be $2500 after all was said and done with timing/fuel control, diagnostic sensors (EGT, wideband O2, tranny temp?).

By all means do it though if you feel up to it, and get pics!

chimmike

EGT is unnecessary if you have a good wideband sensor monitoring.... (innovate product). Tranny temp is also unnecessary if you plumb a custom cooler setup in there. I run 93 octane and I'm at a lower altitude than you so I don't think I'll need that much timing retard....also the fact that the two smaler turbos are more efficient at their boost settings than a t3 is at 5psi will mean slightly cooler charged air.

As it stands right now I almost have enough mandrel bends laying around to do 90% of the intake piping, I also know what fittings are necessary and have good hydraulic supply shops local to me, the SAFC and random flanges will be the most expensive...the turbos can be had cheaply, and the oil sump pump will also be expensive. I still have some good aeroquip line I can use as oil return lines too, and that stuff is $$$$ Shoot, I could even pressure test the intercooler off my totalled Z...or even have it repaired and use it if it leaks, as it's a 3.5" thick spearco unit capable of 600hp with a ~1.5psi max pressure drop

shoes138

yea dood i agree with all these if you got everything just do it! it seem very interesting. but you also gotta look at if the bottom end will put up wit it!

dcg9381

I would have agreed with you until I contributed to my latest turbo demise via high EGTs. I had timing setup (in the non-boost zone) closely to what it should be for an NA motor. Those timing settings are significantly conservative.. Too conservative, actually as retarded timing can result in high EGTs.

I had glowing manifold / glowing turbo after moderate use.
Another turbo owner tried it as an experiment, and ended up with EGTs quickly climbing over 1500.

I'm still not ready to add another gauge to my rig, but it's a valuable tool when tuning... I've got a wideband, my fuel AFRs were right on.

1500 degrees.. my guess is that cast pistons wouldn't last long.. And I'm glad DOA talked me into high end valves on this head.

chimmike

differences abound here though. Especially in that your turbo sits on your manifold which is directly bolted to the head. Mere inches separate the extremely hot turbo from the head itself. This is a prime location for heat to trap and increase in folds.

With a twin setup on the 3vze, there would be enough space and piping between the turbos and the heads to prevent heat from building up excessively in the area around the heads and thereby decreasing EGT's.

While I agree too low/too high timing leads to excessive EGT's, I think stock 10* base timing on the 3vze is conservative enough, especially with the .031" gapped plugs, to be safe on 93 octane, upgraded injectors, and basic boost without needing an EGT. Another thing that decreases the need for that gauge is to make sure your intake temps are as low as possible. Lower intake temps lead to slightly lower exhaust gas temps.

I think EGTs are a bit more effective in diesels, but personally I've had far better response tuning to a precise afr rather than combining the two.

chimmike

I'm thinking a setup like that will make no more than 200whp on the motor. Figure 250bhp after extensive drivetrain losses.

That's far less than 50hp/cylinder, which should be more than reasonable on stock cast pistons.

BlackSR5

Good luck. Keep us posted!

dcg9381

Why are you using base timing as a reference? What matters is the total timing that occurs under "cruise" conditions and under load. You'll typically see high EGTs under cruise, where you're near 14.7:1 - especially if you drop your timing. Try dropping your timing 10 degrees just driving down the road at 70mph and watch your EGTs soar. Base timing does impact total time, for most "distributor" applications anyway - but it's hardly a determination of having enough timing or not.

Under boost is another issue, but you're right - an appropriate A/F helps.

Don't mistake my EGTs for having to do with the location of my turbo. EGTs should be measured near the exhaust ports. If my turbo was located further down in my exhaust system, it might have spared the turbo, but my EGTs would still be too high.. Hard on pistons and hard on valves!


Honestly, though - if you're sticking turbo(s) on a NA compression 3.0 non-boost timing and EGTs won't be an issue...

chimmike

I would never, EVER run a turbocharged vehicle near 14.7:1 at any time except maybe idle. At normal off-boost cruise the leanest I would go is maybe 13:1, and under boost at any time I'd NEVER go higher than 12:1....especially on a n/a motor. That's just my experience with turbo motors. And the ones I've cracked open have been clean so far

Your EGTs are definitely affected by the turbo being so close to the head.....backpressure

and yeah......the 3.slow with 7psi from two small turbos won't have too much to worry about. I'd find out stock injector flow and based on what that is, upgrade it....and that extra flow should be sufficient for the added air being forced in.