Can't choose between 2 turbos

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VF69HARDTOP

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Hi

A body
318 with 9:1 comp
Eddie rpm heads
Victor 340 intake
Lunati solid flat tappet
2400 6600 RPM
235/243 Duration at .050". 110 Degree Lobe Separation Angle
0.526"/0.546" Valve Lift
Holley sniper throttle body injection
2500rpm stall
3.45 diff gear

Looking to make around 800FWHP
but can't decide between these two turbos, so I'm after some advice on the two please?

T4 7875
Compressor Specifications
Inducer: 78.13mm
Exducer: 102.40mm
Extended Tip: 106.30mm
Compressor Inlet: 4" slip fit
Compressor Outlet: 2.5" slip fit
Turbine Specifications
Inducer: 82mm
Exducer: 75mm
A/R: 0.96
Turbine Inlet Flange: T4
Turbine Outlet Flange: V-Band

Or

T4 6973
Compressor Specifications
Inducer: 69mm
Exducer: 92.50mm
Extended Tip: 96.40mm
Compressor Inlet: 4" slip fit
Compressor Outlet: 2.5" slip fit
Turbine Specifications
Inducer: 79.70mm
Exducer: 73.50mm
A/R: 0.91
Turbine Inlet Flange: T4
Turbine Outlet Flange: V-Band
 
The 7875 is supposed to be more than capable at that power level. Word on the street though is that 318 block is not gonna work above 700 hp.

Would be interesting to see someone build up a sb somewhat conservatively, and with a good professional tune, how much power it really does hold.
 
I agree with Mean416 about the 78, will be plenty for that power. Stud everything, can try the main girdle too. Go with a good blue printed oil pump with higher volume so you can feed the engine and the turbo like this one SB Mopar - Precision Oil Pumps
 
Matts440 said:
I agree with Mean416 about the 78, will be plenty for that power. Stud everything, can try the main girdle too. Go with a good blue printed oil pump with higher volume so you can feed the engine and the turbo like this one SB Mopar - Precision Oil Pumps
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Thanks. I have that oil pump on the shelf, just needs checking before installation.

Do you know of anyone that's used a 7875 on a 318?
 
You can have studs stickin outta your *** if you want, but the 318 block will not handle much more then 600-650HP at the flywheel. 800WHP is aftermarket block territory. A big block would work better.
 
I'd be very interested in a "big bang" video on a 360.
 
RustyRatRod said:
You can have studs stickin outta your *** if you want, but the 318 block will not handle much more then 600-650HP at the flywheel. 800WHP is aftermarket block territory. A big block would work better.
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What's considered to be the weak point of the block?
 
VF69HARDTOP said:
What's considered to be the weak point of the block?
Click to expand...
I would suspect somewhere in the bottom, such as the meat around the main saddles, or the main saddles themselves. No girdle in the world is going to stop the inevitable. Hold it off for a while......maybe, but if you build an 800-850HP engine with a stock block, you better have another one waiting in the wings. How much boost do you think it will take? Headin towards if not over 20PSI is my guess. A stroked 360 (408 or 416) could make the power more easily with less boost, but it's still WAY more than a stock block can handle. Build it. It'll be a bad **** for a while.
 
RustyRatRod said:
I would suspect somewhere in the bottom, such as the meat around the main saddles, or the main saddles themselves. No girdle in the world is going to stop the inevitable. Hold it off for a while......maybe, but if you build an 800-850HP engine with a stock block, you better have another one waiting in the wings. How much boost do you think it will take? Headin towards if not over 20PSI is my guess. A stroked 360 (408 or 416) could make the power more easily with less boost, but it's still WAY more than a stock block can handle. Build it. It'll be a bad **** for a while.
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I'm hoping the engine will make around 400 fwhp and then add boost from there. I'm limiting boost to no more than 14-15psi,so it might make 700 ish fwhp, fingers crossed. But then again, I might decide to stop at 600 fwhp to help it live.
My line of thought is that by adding boost, I don't need such an angry NA engine to make the power and it'll keep it nicer to drive.
 
VF69HARDTOP said:
I'm hoping the engine will make around 400 fwhp and then add boost from there. I'm limiting boost to no more than 14-15psi,so it might make 700 ish fwhp, fingers crossed. But then again, I might decide to stop at 600 fwhp to help it live.
My line of thought is that by adding boost, I don't need such an angry NA engine to make the power and it'll keep it nicer to drive.
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And that's the way to think. I like the overall plan. It's kinda how the factory made turbocharged engines. Very mild, but powerful. Build it. It'll be fun while it lasts. But be prepared. lol
 
RustyRatRod said:
And that's the way to think. I like the overall plan. It's kinda how the factory made turbocharged engines. Very mild, but powerful. Build it. It'll be fun while it lasts. But be prepared. lol
Click to expand...
If it fulls apart, I'll have to put a dirty LS in it hahaha
 
I think it would be interesting to do the big bang because we could learn more about what the weak link is. Of course there's a limit. But who knows what is the real cause?

For example, maybe a shorter stroke engine, with higher boost levels and lower rpm could actually get to the higher power levels.
 
If the consequences of blowing up the small block are an LS, give yourself a chance with a BB. One of those 400 smog motors. If smooth running/bigger HP is the goal, I believe there is a recipe that follows the thought of big cubes/small cam/boost. but I have never personally done it. I am rooting for ya!
 
Ill disent and say the smaller with the smaller A/R will spool faster and give you more useable power under the curve instead of a big hop up when the bigger turbo starts to spool. Stud the bottom, stud the top, ARP the H beam rods, forged pistons. O-ringed block with copper head gaskets...All the help the teen can muster for turbo strength and durability. Gen 3...just add turbo.
 
pishta said:
Ill disent and say the smaller with the smaller A/R will spool faster and give you more useable power under the curve instead of a big hop up when the bigger turbo starts to spool. Stud the bottom, stud the top, ARP the H beam rods, forged pistons. O-ringed block with copper head gaskets...All the help the teen can muster for turbo strength and durability. Gen 3...just add turbo.
Click to expand...

After adding ring gap
 
@RustyRatRod
Mean416 said:
I think it would be interesting to do the big bang because we could learn more about what the weak link is.
Click to expand...

I'll be your Huckleberry! LOL!

So, I have this Procharged 408" engine in my long mothballed 1970 'cuda. Nothing wrong with the engine, it was more the money, body, and the wiring as to why it is sitting. Also ignition and timing control parts mismatch (MSD 6A w/ no boost retard controller).

I am wrapping up Arthur's Duster and the Cuda is finally going to the bodyshop next summer. I was planning on revamping the 408" and putting the right charge air cooling parts on it, an MSD Programmable box with a MAP sensor, and a Snow water methanol kit. BUT, I just bought @Johnny Mac 's twin turbo set up he was going to put on his late Charger. I have a MP 380hp crate 360 Magnum block for a back up. The Procharger has thrown a belt on two occasions and, I dunno, maybe there is some other excuse for switching to turbos.

Exhaust (Turbo Manifold) Flange: T3 T4 4 bolt Flange Patterns
Exhaust (Downpipe) Flange: V-Band Flange
Cooling Type: Oil Cooled
Wastegate: Internal Wastegate
Horse Power: Boost Horse Power up to 420HP


Compressor:
Trim: 44
Inducer Diameter:50.5 mm
Exducer Diameter:76 mm
A/R:0.5


Turbine
Trim:73
Inducer Diameter:65.5 mm
Exducer Diameter:55.9 mm
A/R:0.63
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The OP should key in on my engine's internals to build a reliable combo up to it's dyno proven 650hp / 600lbft :
1971 360 block (high nickle, blue printed, good wall thickness). K1 forged crank, K1 forged h-beam rods, forged Diamond Racing pistons. Hughes main girdle, Hughes ported Edelbrock heads, Cometic head gaskets, 224 @ .050 duration / 114 LSA, bushed lifter bores and hyd. roller lifters, studs throughout, Super Victor intake, 750 cfm blowthrough carb, ported oil pump, 1.5 roller rockers, ....

Again, it hasn't ran in 7-8 (9?) years. I have primed the pump and rotated it 1-2 times a year but I do plan to tear it down and check everything. It has less that 10,000 miles on it. It ran no more than 7.5 psi and I plan to not go past 10 psi with the turbos. I am happy with the power it had but I would like to dyno it again with the twin Hong Kong spinny bois and do not want to exceed 700hp for the block. Will it live?

I am worried that the turbos may be too big actually, says they're good for 420hp. So, x2, minus intercooler loss. AND, they might be just right as I am not well versed with turbos or how to decipher all the numbers.

I want to try to fit an intercooler if at all possible but I do have the new water methanol kit. I also kinda want to stick with the carb because I have the MSD box and carb that is for boost already ($$$). However, if a Holley FI or FiTech system will help make it safer under boost I will be inclined to go that route.

Hopefully, by next winter the engine and car will be revamped so be on the lookout for an LA engine D1-SC Procharger kit for sale, possibly with the blowthrough, MSD Programmable 6, and water methanol kit.
 
600-650 would likely last a long time driven respectably. I'd endorse that with a "WELL" prepared factory block. But we're talk about a 318 here and the OP seems pretty dead set on his power goals. He's gonna break stuff. It'll be fun while it lasts, though.
 
The vsr6973 billet turbo (if that’s what you are considering) is a 900hp turbo. Plenty for your goals. The vsr billet next gen 7875 is 1000hp capable. Of the two you listed I’d use the 6973 on a 318. I would recommend using some of the online turbo sizing calculators to determine the mass flow of your engine and select a turbo to be in an efficiency range that is near 75% at the boost you want to run so it will live a long happy life. Garret has a great calculator online.

Choose a Turbo
 
TT5.9mag said:
The vsr6973 billet turbo (if that’s what you are considering) is a 900hp turbo. Plenty for your goals. The vsr billet next gen 7875 is 1000hp capable. Of the two you listed I’d use the 6973 on a 318. I would recommend using some of the online turbo sizing calculators to determine the mass flow of your engine and select a turbo to be in an efficiency range that is near 75% at the boost you want to run so it will live a long happy life. Garret has a great calculator online.

Choose a Turbo
Click to expand...
Thanks for your thoughts.
I'm also looking at the Pulsar S372 journal bearing with a .91 twin scroll exh housing. It seems to sit in between the 7875 & 6973 so could be a good match.
What's your thoughts on this one?
Thinking I might bring the power goal back to 700fwhp Max so hopefully help it live a little longer. I'll also opt for a smaller cam to keep rpm Max at 6000rpm.

Thanks

Screenshot_20220809-201950_eBay.jpg
 
Go with a custom grind cam, turbos like a bigger a bigger intake. Like the one I have is almost flipped of the cam you listed at 243/239. Helps with spool better.
 
VF69HARDTOP said:
Thanks for your thoughts.
I'm also looking at the Pulsar S372 journal bearing with a .91 twin scroll exh housing. It seems to sit in between the 7875 & 6973 so could be a good match.
What's your thoughts on this one?
Thinking I might bring the power goal back to 700fwhp Max so hopefully help it live a little longer. I'll also opt for a smaller cam to keep rpm Max at 6000rpm.

Thanks

View attachment 1715967930
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I have zero experience with that brand of turbo, really I’ve never even heard of them. But the specs you posted seem to mirror the 6973 pretty closely. The two are not much different. The cam you choose will not “limit” rpm per se, it will determine where power and torque peaks occur but boost makes an airflow limited engine rpm really well. Matt’s comment above to work with a cam company for a grind specific to your application is good advice.
 
I know turbos and superchargers have differences but, FWIW, I worked with Hughes Engines and had them spec a cam for my Procharger. They work with The Supercharger Store a lot on their cams. I was very happy with the driveability of my car.
 
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