Any proven turbo combinations out their for the 300?

clintonvillian

Famous Member
Hoping to get some feedback on the guys actually running theirs. We all can play on calculators, but I'd like to hear more from the guys running them.

Specifically, make, model, configuration, and any performance issues, or recommendations you would have (internal vs external waste gate, A/R ratios, intercoolers, etc).




I am getting ready to get into the meat of my build, mounting the supercharger. I have done some price checking, and for the cost of a rebuild and port and polish job I can buy a new name brand turbo. So it is making me question the feasibility of the supercharger, I don't see any advantage to it over a turbo. I am not killing it yet, but definitely looking at options. That price is not including a custom crank pulley, idler pulley, and cost in fabbing up the mounts. It is a 1500.00 swing......
 
Thanks bubba22349! The pics help the looks a little...

Lots of info in there, 3 different cams, 2 different turbos, with all the details along the way.

Here is a shortcut to all the videos in the thread: https://www.youtube.com/channel/UCh21RL ... _as=public

I wanted to start my build thread here, but had issues trying to register, I think on my end. Would like to start a condensed/up to date thread here. Which area would be the best?
 
Well you could post it in the Turbo section or the 240 / 300 big six forum or even both. The big six section would likely get more views, but there is a very dedicated 300 six group also in the turbo section. Good luck :nod:
 
While I've not played with cams yet, my Holset HX35 is doing well for my needs, which is a used turbo off a mid to late 90's Dodge Cummins. They are very affordable and can be easily rebuilt with new bearings and seals for under $50. Depending on your boost goals, the "Chinacharger" Ebay turbos are actually not terrible. As long as you dont plan over 20psi of boost, they last long enough and are dirt cheap. Thats all in what you like though, I completely understand if you just don't want to mess around with cheap parts.

My completely stock 95 motor spools around 2500 rpm with an exhaust leak at the flange.
 
Hey sick6turbo, what did exact Holley did you use? Was it modified? I don't understand the tuning that goes into turbo carbs. Would a high volume electric feed too a single feed 600cfm accomodate a lower psi like 15?
 
mekta3":3au5v9xe said:
Hey sick6turbo, what did exact Holley did you use? Was it modified? I don't understand the tuning that goes into turbo carbs. Would a high volume electric feed too a single feed 600cfm accomodate a lower psi like 15?

Holley 4776

Mods: Machine all surfaces. Holleys are very crooked. Don't worry about the fuel bowl sealing bead, machine it/them flat.

Solids floats,(e85 metering blocks, not necessary with gas), external power valve control using the Cure.

Tune idle and main jets same as n.a., and tune pvrc (power valve restrictor channels) during boost.

Good links to cover the basics: http://members.tccoa.com/392bird/tuning.htm

http://members.tccoa.com/392bird/carbtech.htm

High pressure such as efi fuel pumps with return style regulators such as Mallory 4309 is the best way. Some lower boost applications (typically 10 psi and lower)can get away with boost referencing the stock mechanical fuel pump, to increase fuel pressure 1:1 with boost.

Ran a stock 300-6/hx35 turbo with a holley 350 2v, solid float, pvrc drilled out one step at a time as needed, and referenced the stock mechanical fuel pump= (pressure line from the hat to the fuel pump vent, plugging the other fuel pump vent to seal.) "8.5" power valve. Ran 13 psi on that for a long time. Sometimes when shifting into 4th gear, when the rpms and flow were low and hat pressure was high, it would partially shut the power valve and go lean while boosted. A higher number power valve such as a "10.5" with a stronger spring would have helped, but possibly dump fuel too soon for n.a. driving. So, the Cure was developed to tune the carb for good n.a. driving, and guarantee the power valve would stay wide open while boosted.

viewtopic.php?f=22&t=74210 (I'm sure you have read this already)
 
With the gt45 turbo and Crower 284, on the transbrake, I had 1psi@3100, 2psi@3200, 3psi@3300 ect... It's a 3000-3100 stall and as boost rose, increasing tq, the stall rose with it. The turbo spools or really takes off at 3800. There is so much tq that the rpms and boost shoot up to 5000 and 20psi respectfully right now as seen in the vids. I would guess 4500-4700 full boost. With the big turbine housing is has a wide range. With the t72 turbo, it started making boost at 2800 and full boost at 3200 when I had the other converter in there.

Now with the Lunati 277 and gt45, It spools a bit quicker and a little lower rpm. When the converter is warm and on the transbrake, boost and rpm come up fast enough that I can't pinpoint when it spools. Will have to get a video camera mounted in there.

In a nutshell:
1psi@3100
spools@3800
full boost@4500-4700
 
Your installation is so befitting a truck that it has me thinking about doing the same.
Mine is stock except for intake and headers and I was thinking of using a Holset HX35Y turbo.
I have a water injection system that I got on trade so I'll be using it also in an under the carb plate.

All just stuff to think about for now, since I really need to put a new floor in my boat for spring Tarpon season.

Thanks
 
You bet! Hx35 and stock 300 seem to be a good fit, with the turbo being relatively transparent in normal driving until called upon. (y)

I should also add, that going from the t72 to the bigger gt45 honestly only increased power by 5-10hp. Nothing to write home about. The engine did feel much smoother and more free however.

There is a guy that dyno tested different turbine a/r housings on the same turbo, same car. From a housing that choked the engine at 6000 (.68)to a housing that let it make power to 6800 rpm (.96), it gained only 16 rwhp. Tq numbers were higher on the smaller a/r, and he said it was a lot more fun on the street.

I have been seeking the lowest back pressure I can with the limited stock 300 head, it does make a little more power, less heat, more possibilities of exhaust scavenging and camshafts with more overlap @.050.

However, there is also a guy with built 363 sbf with 25psi boost making 1100hp (dyno) with a turbine housing and wheel smaller than the gt45 but more effecient (Precision 76/75). The class he races limits him to that size turbo, single turbo only. It takes 1.15 seconds from fast idle to make 25psi! Serious back pressure and I bet his .680 lift solid roller has plenty of overlap @.050 even with a wide lsa.
 
Sick6Turbo":gjk4nqxq said:
You bet! Hx35 and stock 300 seem to be a good fit, with the turbo being relatively transparent in normal driving until called upon. (y)

I should also add, that going from the t72 to the bigger gt45 honestly only increased power by 5-10hp. Nothing to write home about. The engine did feel much smoother and more free however.

There is a guy that dyno tested different turbine a/r housings on the same turbo, same car. From a housing that choked the engine at 6000 (.68)to a housing that let it make power to 6800 rpm (.96), it gained only 16 rwhp. Tq numbers were higher on the smaller a/r, and he said it was a lot more fun on the street.

I have been seeking the lowest back pressure I can with the limited stock 300 head, it does make a little more power, less heat, more possibilities of exhaust scavenging and camshafts with more overlap @.050.

However, there is also a guy with built 363 sbf with 25psi boost making 1100hp (dyno) with a turbine housing and wheel smaller than the gt45 but more effecient (Precision 76/75). The class he races limits him to that size turbo, single turbo only. It takes 1.15 seconds from fast idle to make 25psi! Serious back pressure and I bet his .680 lift solid roller has plenty of overlap @.050 even with a wide lsa.

On a log exhaust manifold the exhaust strokes are 120 degrees apart. Instead of scavenging, you have exhaust pressure pulses pressurizing the next cylinder in the firing order before the exhaust valve closes.
The front 3 cylinders need to be isolated from the back 3 cylinders giving 240 degrees separation between exhaust pressure pulses in the manifold. Far less cylinder to cylinder interaction.

We made 2000+ hp with a 430 SBF with twin precision 88s at 8000 rpm. 25 lbs of boost
Cam .050" durations in the 260s with lifts over .900". Lots of overlap by virtue of the lobe duration needed to get the rpm, not by choice.
A/R over 1.0. Average exhaust pressure the same as boost pressure.
2 seconds from fast idle to the foot break limiter coming into the lights and another 2 seconds on transbrake to launch boost.
 
I've wondered how the stock efi exhausts manifolds with dual 2" pipe all the way back to a divided entry turbo would perform compared to the 6-1 log and single 2.5" pipe. I was going to built a tubular split scroll turbo header for the tp38 front mount I'm building. But after realizing it's the front 3 and back 3 cylinders I have to pair, it's going to be way easier for me and cheaper to keep my efi manifolds and run to short 2" up pipes to a t4 flange for my turbo. Still technically twin scroll though not come rely tubular. We'll see how it works out for me I'm trying to get the quickest spool out of that big exhaust wheel. Already purchased a .84 ar housing which is the smallest available
 
Well I'm keeping my headers only because they were such a pain to put on in the first place.
Need 6 arms for some jobs and I'm a little short.
 
just came across your thread sorry its a bit late. efi manifolds with a merging y pipe, ran a gt35 (ebay turbo) t4 .68ar housing 3"vband, positive pressure around 1800rpm all in 15psi+ 22-2500 rpm pending on load, found the turbine to be too small for highway cruising awesome towing and torque for 4x4, too much backpressure pipes start glowing at 115-120kph, with that same turbo i was going to run a .81/.82 ar turbine housing.. however i went to a larger turbo and housing for kicks recently, t76 t4 .96ar turbine 3"vband, positive pressure around 2000 rpm, full 15lbs 2800rpm-3000rpm, smooth transition, makes nearly the same bottom end as the old turbo just a bit slower/smoother coming on, as far as street ability i like it better even though it spools later. also find the top end has picked up drastically. hoping with a cam swap to utilize the head work, should make this think work better down low, was going to go to a .82 ar on the new turbo but im really starting to like how it comes on, you dont realize how much its pulling until you let off, also quieter and more discreet on the compressor side. the gt35 would constantly have a turbo wine if your into that sort of thing, also spooled violently quick down low, top end choke out/stop pulling hard around 4000-4500rpm but would carry on to 5k if you held it.
 
Sick6Turbo":cwbrazs1 said:
:nod: Stock 300+hx35= 2500 rpm spool, 3000 rpm grinometer pegged.

I'm interested in a stock 300-turbo build. Any more info on your setup? How much boost do you get? How does it perform at interstate speeds (60-70mph)? And what else did you put in with it (injectors, blow off, intercooler, etc.)
 
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